United States
Environmental Protection
Agency
PA's Report on the Environment
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U.S. Environmental Protection Agency
Washington, DC 20460
EPA/600/R-07/045F
May 2008
EPA's Report on the Environment
Recycled/Recyclable—Printed with Vegetable Oil Based Inks on 100% Postconsumer, Process Chlorine Free Recycled Paper
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DISCLAIMER
This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication.
Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
Preferred Citation:
U.S. Environmental Protection Agency (EPA). (2008) EPA's 2008 Report on the Environment. National Center for Environmental
Assessment, Washington, DC; EPA/600/R-07/045F. Available from the National Technical Information Service, Springfield, VA, and
online at http://www.epa.gov/roe.
EPA will update the environmental indicators presented in this report when data become available. Please visit the electronic report at
www. epa.gov/roe for the most up-to-date information on the Report on the Environment.
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Message from the Assistant Administrator
for Research and Development
I am pleased to present EPA's 2008 Report on the Environment (ROE).
This report compiles, in one place, the most reliable indicators currently
available to answer key questions about trends in human health and the
condition of the nation's environment.
EPA's 2008 Report on the Environment demonstrates the importance of
scientifically sound information to help us understand the state of the
environment, identify areas of concern, and monitor progress. We can all
celebrate the fact that our air is cleaner, our water is purer, and our land is
better protected than it was just a generation ago. Today, we are beginning
to measure just how much progress we have made. Though we once
took our environment for granted, we now understand the importance
of environmental quality for our future. Much work remains to be done,
however, and we must continue to build on our record of progress.
I thank the many EPA staff members from every program and Region; our
federal, tribal, state, and local government partners; and the independent
scientists and research institutions who contributed to this report. The
2008 ROE represents the culmination of an effort that began in 2001
when EPA embarked on a bold initiative to assemble, for the first time,
indicators of national conditions that are important to the Agency's mission
to protect human health and the environment. EPA first presented this
information in its 2003 Draft Report on the Environment. We have since
revised and refined the ROE in response to feedback from EPA's Scientific
Advisory Board and our stakeholders, and we have updated the indicators
to reflect the latest available data.
EPA's 2008 Report on the Environment is part of an important national
dialogue on how we can improve our ability to assess the nation's
environmental quality and human health, and how we can use that
knowledge to better manage for measurable environmental results.
I invite you to participate in this dialogue with us and our partners.
Your comments and feedback are essential to our future efforts.
George Gray, Ph.D.
Science Advisor and
Assistant Administrator for
Research and Development
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Acknowledgements
Development of this report was a collaborative effort that could not have been
accomplished without the substantial commitment of many people, both inside
and outside EPA. EPA thanks the following individuals and organizations for their
contributions to this effort.
ROE Leads
Denice Shaw - Project Lead (EPA)
Peter Preuss — Director,
National Center for Environmental
Assessment (EPA)
Core ROE Team
Arden Calvert (EPA)
Cynthia Curtis (EPA)
Danelle Lobdell (EPA)
Guy Tomassoni (EPA)
Heather Case (EPA)
James Canavan (EPA)
Jay Messer (EPA)
Julie Damon (EPA)
Macara Lousberg (EPA)
Maricruz MaGowan (EPA)
Marjorie Jones (EPA)
Michael Hadrick (EPA)
Monica Jones (EPA)
Patricia Murphy (EPA)
Rebecca Calderon (EPA)
William Nickerson (EPA)
EPA Office/Region Leads
Ann Williamson (EPA)
Barbara Kheforth (EPA)
Beth Walls (EPA)
Brenda Groskinsky (EPA)
Carmen Maso (EPA)
Debra Forman (EPA)
Gerard Bulanowski (EPA)
Matthew Hoagland (EPA)
Michelle Hiller-Purvis (EPA)
Nicoletta DiForte (EPA)
Nora McGee (EPA)
Randolph Perfetti (EPA)
Richard Sumpter (EPA)
Ronald McHugh (EPA)
Stuart Kerzner (EPA)
Vance Fong (EPA)
William Rhea (EPA)
Wmona Victery (EPA)
Contributors
Adam Sapp (LUMCON)
Alan Herhhy (EPA)
Andrea Cherepy (EPA)
Anne Grambsch (EPA)
Anne Keller (EPA)
Anne Marsh (Heinz Center)
Anne Pope (EPA)
Arthur Flaks (EPA)
Barry Burgan (EPA)
Belinda Hawkins (EPA)
Bill Wilber (USGS)
Brad Schultz (EPA)
Brad Smith (USDA Forest Service)
Bruce Stein (NatureServe)
Carrie Knowlton (ASPH/EPA Fellow)
Charles Aloe (ASPH/EPA Fellow)
Charles Maurice (EPA)
Cheryl Pressley (EPA)
Chris Davis (CommEnSpace)
Chris Zervas (NOAA)
Cindy Heil (Florida Fish and Wildlife
Research Institute)
Claudia Walters (EPA)
Coe Owen (EPA)
Colleen Haney (EPA)
Collm Homer (USGS)
Cpan Lee (EPA)
Dan Axelrad (EPA)
Dan Petersen (EPA)
David Hrdy (EPA)
David Mmtz (EPA)
David Schmeltz (EPA)
Deborah Burgm (EPA)
Dennis Beauregard (EPA)
Dennis Doll (EPA)
Devon Payne-Sturges (EPA)
Dick Reynolds (NOAA)
Donna Myers (USGS)
Doreen Vetter (EPA)
Douglas Solomon (EPA)
Elizabeth Corr (EPA)
Elizabeth Jackson (EPA)
Ellen Tarqumio (EPA)
Eric Leuliette (NOAA)
Erik Winchester (EPA)
Ethan McMahon (EPA)
Ethel Brandt (EPA)
Fred Dimmick (EPA)
Gilberto Alvarez (EPA)
Grace Smith (EPA)
Gretchen Smith
(University of Massachusetts)
Heather Shoven (EPA)
Henry Lee (EPA)
Henry Schuver (EPA)
Hope Pillsbury (EPA)
Ingrid Sunzenauer (EPA)
James Hemby (EPA)
James Wickham (EPA)
Jan Moneysmith (EPA)
Jane Leggett (EPA)
Jason Samenow (EPA)
Jawauna Greene (EPA)
Jay Lawrimore (NOAA)
Jeanne Allen (EPA)
Jeff Cohen (EPA)
Jennifer Margolies (EPA)
Jessica Smith-Armstrong (EPA)
Jim Afghani (EPA)
Jim Cabot (EPA)
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Jim Pendergast (EPA)
John Coulston (USDA Forest Service)
John Macauley (EPA)
John Richardson (EPA)
John Stoddard (EPA)
John Van Sickle (EPA)
Jon Schweiss (EPA)
Jonathan Hall (EPA)
Joseph Greenblott (EPA)
Katharine Dowell (EPA)
Kenneth Dixon (EPA)
Kent Cavender-Bares (Heinz Center)
Kevin Summers (EPA)
Kurt Riitters (USDA Forest Service)
Lael Butler (EPA)
Lara Akinbami (CDC)
Larry Master (NatureServe)
Larry Reisman (EPA)
Larry Starfield (EPA)
Laura Nielsen (EPA)
Lawrence Martin (EPA)
Leanne Stahl (EPA)
Lee Kyle (EPA)
Linda Heath (USDA Forest Service)
Linda Young (University of Florida)
Marc Pitchford (NOAA)
Margaret Sheppard (EPA)
Mark Sather (EPA)
Mark Tedesco (EPA)
Mary Christman (University
of Florida)
Mary White (EPA)
Melanie Hoff (EPA)
Melanie Magee (EPA)
Michael McDonald (EPA)
Michael Rylko (EPA)
Motria Caudill (EPA)
Myra Price (EPA)
Nancy Baker (USGS)
Nancy Rabalais (LUMCON)
Nancy Wentworth (EPA)
Neil Burns (EPA)
Nicole Paquette (EPA)
Nita Sylvester (EPA)
Phil Kaufmann (EPA)
Phil Lorang (EPA)
Philip Jalbert (EPA)
Priscilla Halloran (EPA)
Ravi Rao (EPA)
Renee Dagseth (EPA)
Richard Haeuber (EPA)
Richard Norris (EPA)
Rick Durbrow (EPA)
Robin O'Malley (Heinz Center)
Rona Birnbaum (EPA)
Roseanne Lorenzana (EPA)
Roy Simon (EPA)
Ruth Knapp (EPA)
Sean Hogan (EPA)
Sherri White (EPA)
Stan Meiburg (EPA)
Steve Montzka (NOAA)
Steve Nerem (University of Colorado)
Steve Paulson (EPA)
Susan Holdsworth (EPA)
Suzanne Annand (EPA)
Tamara Saltman (EPA)
Thomas Armitage (EPA)
Thomas Forbes (EPA)
Tim Lewis (EPA)
Tim Wade (EPA)
Tom Dahl (Fish and Wildlife Service)
Tom Loveland (USGS)
Tom Smith (NOAA)
Tony Olsen (EPA)
Tracey Miller (EPA)
Tracey Woodruff (EPA)
Velu Senthil (EPA)
Veronica Blette (EPA)
Vipul Bhatt (EPA)
Virginia Engle (EPA)
Walter Schoepf (EPA)
Wen Huang (USDA)
Environmental Indicators
Steering Committee
Bharat Mathur (EPA)
Clifford Gabriel (EPA)
Donald Welsh (EPA)
Ed Chu (EPA)
George Gray (EPA) (Co-chair)
Hal Zenick (EPA)
Ira Leighton (EPA)
Jerry Clifford (EPA)
John Reeder (EPA)
Kathy O'Brien (EPA)
Kimberly Nelson (EPA)
Linda Travers (EPA)
Louise Wise (EPA)
Maryann Froehlich (EPA)
Mike Shapiro (EPA)
Molly O'Neill (EPA) (Co-chair)
Norm Neidergang (EPA)
Ray Spears (EPA)
Rob Brenner (EPA)
Ron Kreizenbeck (EPA)
William Sanders (EPA)
Indicator Peer Reviewers
Anitra Pawley
Bailus Walker
David Fairley
Debra Reinhart
George Hepner
George Hidy
Hans Paerl
James Carlisle
James Listorti
John Day
Kevin Armbrust
Kevin Civerolo
Lawrence Kapustka
Lyle Chinkin
Lynn Goldman
N. Scott Urquhart
P. Barry Ryan
Robert Pojasek
Stanley Gregory
Steven Bartell
Terry Spittler
William Creal
2007 Science Advisory
Board Panel
Aaron Cohen
Alan Steinman
Allan Legge
Barry Wilson
Chi-Yeung John Suen
David Dzombak
Deborah Neher
Deborah Swackhamer (Chair)
Dennis Grossman
Duncan Patten
Fred Benfield
Gary Sayler
George Lambert
Henry Anderson
Judith Weis
M. Granger Morgan
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Maria Morandi
Mark Borchardt
Philip Hopke
Ramesh Reddy
Robert Twiss
Timothy Buckley
2003 Science Advisory
Board Panel
Alan Steinman
Ann Marie Gebhart
Arturo Keller
Charles Kolb
Cynthia Warrick
George Lambert
John McManus
Joseph Bunnell
Joseph Helble
Kathryn Saterson
Maria Morandi
Mark Bain
Mark Schwartz
Norman LeBlanc
Oswald Schmitz
Peter Scheff
Philip Bromberg
Stephen Trombulak
Timothy Buckley
Virginia Dale (Chair)
Interagency Reviewers
Al Cobb (DOE)
Anthony Swift (DOT)
Benjamin Simon (DOI)
Camilla Mittelholtz (DOT)
Christine McDonald (OMB)
Claudia McMurray (State of
California)
Drue Barrett (CDC)
Edward Stern (DOL)
Edwin Foulke (DOL)
Edwin Pmero (OFEE)
Hodayah Finman (DOS)
Jack Kaye (NASA)
Janet Irwin (OMB)
Jens Svenson (DOL)
John (Jack) Brellenthm (TVA)
Kevin Neyland (OMB)
Kimberly Miller (OMB)
Marge Cavanaugh (NSF)
Mark Bashor (CDC)
Mary Glackm (NOAA)
Maureen Dunn (TVA)
Patricia Ferrebee (OSD)
Rex Geveden (NASA)
Shawn Alam (DOI)
Shelia Newton (NIH)
Ted Hemtz (CEQ)
Teresa Fryberger (OSTP)
Captain Todd Stiles (NOAA)
Vijam Rai (DOI)
Willie Taylor (DOI)
Woodie Kessel (DHHS)
Communications and
Publications
Crystal Samuels (EPA)
Linda Bailey-Becht (EPA)
Linda Tuxen (EPA)
Maureen Johnson (EPA)
Melissa Anley-Mills (EPA)
Robert Cassell (EPA)
Contractor Support
Team Leads
Eastern Research Group, Inc. (ERG)
Chris Lamie
Jan Connery (Project Manager)
Jenny Helmick
John Wilhelmi
Linda Cook
Naida Gavrelis
Ross & Associates
Environmental Consulting, Ltd.
Nancy Tosta
Menzie-Cura & Associates, Inc.
Charles Menzie
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Contents
1 Introduction i-i
2 Air
2.1 Introduction 2-3
2.2 What Are the Trends in Outdoor Air Quality and Their Effects on
Human Health and the Environment? 2-6
2.3 What Are the Trends in Greenhouse Gas Emissions and Concentrations? 2-62
2.4 What Are the Trends in Indoor Air Quality and Their Effects on Human Health? 2-73
3 Water
3.1 Introduction 3-3
3.2 What Are the Trends in the Extent and Condition of Fresh Surface Waters
and Their Effects on Human Health and the Environment? 3-6
3.3 What Are the Trends in the Extent and Condition of Ground Water
and Their Effects on Human Health and the Environment? 3-25
3.4 What Are the Trends in the Extent and Condition of Wetlands
and Their Effects on Human Health and the Environment? 3-30
3.5 What Are the Trends in the Extent and Condition of Coastal Waters
and Their Effects on Human Health and the Environment? 3-35
3.6 What Are the Trends in the Quality of Drinking Water and Their Effects on Human Health? 3-52
3.7 What Are the Trends in the Condition of Recreational Waters
and Their Effects on Human Health and the Environment? 3-57
3.8 What Are the Trends in the Condition of Consumable Fish and Shellfish
and Their Effects on Human Health? 3-59
4 Land
4.1 Introduction 4-3
4.2 What Are the Trends in Land Cover and Their Effects on Human Health and the Environment?. . . 4-5
4.3 What Are the Trends in Land Use and Their Effects on Human Health and the Environment? .... 4-13
4.4 What Are the Trends in Wastes and Their Effects on Human Health and the Environment? 4-23
4.5 What Are the Trends in Chemicals Used on the Land and Their Effects on Human Health
and the Environment? 4-29
4.6 What Are the Trends in Contaminated Land and Their Effects on
Human Health and the Environment? 4-42
5 Human Exposure and Health
5.1 Introduction 5-3
5.2 What Are the Trends in Human Exposure to Environmental Contaminants,
Including Across Population Subgroups and Geographic Regions? 5-7
5.3 What Are the Trends in Health Status in the United States? 5-31
5.4 What Are the Trends in Human Disease and Conditions for Which Environmental Contaminants
May Be a Risk Factor, Including Across Population Subgroups and Geographic Regions? 5-39
6 Ecological Condition
6.1 Introduction 6-3
6.2 What Are the Trends in the Extent and Distribution of the Nation's Ecological Systems? 6-7
6.3 What Are the Trends in the Diversity and Biological Balance of the Nation's Ecological Systems? . 6-18
6.4 What Are the Trends in the Ecological Processes That Sustain the Nation's Ecological Systems?. . 6-27
6.5 What Are the Trends in the Critical Physical and Chemical Attributes
of the Nation's Ecological Systems? 6-31
6.6 What Are the Trends in Biomarkers of Exposure to Common Environmental Contaminants
in Plants and Animals? 6-45
7 Afterword 7-1
Appendix A Acronyms and Glossary A-i
Appendix B Development of EPA's 2008 ROE B-i
Appendix C Comparison of Indicators Used in EPA's 2008 ROE and the 2003 Draft ROE c-i
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1. Introduction
To accomplish its mission, the U.S. Environmental Protec-
tion Agency (EPA) must pay close attention to trends in
the condition of the nation's air, water, and land, and to
associated trends in human exposure and health and the condi-
tion of ecological systems. Data on environmental trends serve
two key purposes: they provide valuable input to EPA in devel-
oping its strategic outlook and priorities, and they allow EPA
and the public to assess whether the Agency is succeeding in its
overall mission to protect human health and the environment.
EPA prepared this Report on the Environment (ROE) to accom-
plish these purposes.
In 2001, EPA embarked on a bold initiative to assemble, for
the first time, an extensive set of environmental indicators that
are important to its mission. EPA presented these indicators in
its Draft Report on the Environment Technical Document, released
in 2003. Since then, EPA has revised, updated, and refined the
ROE in response to scientific developments and to feedback
from public stakeholders and EPA's Science Advisory Board
(SAB). EPA's 2008 Report on the Environment presents the
results of this work.
The 2008 ROE compiles, in one place, the most reliable
indicators currently available to answer 23 questions that EPA
believes are of critical importance to its mission and the nation's
environment. The indicators are supported by data gathered
from federal and state agencies and non-governmental organiza-
tions. All of the indicators were peer-reviewed to meet exacting
standards for accuracy, representativeness, and reliability. This
2008 ROE presents trends wherever adequate data are currently
available, and it establishes reliable national baselines where they
are not. Equally important, the report identifies key limitations
of these indicators and gaps where reliable indicators do not
yet exist. This report does not propose actions to reduce data
limitations or fill gaps, nor does it analyze the costs and benefits
of doing so.
EPA's 2008 Report on the Environment
1-1
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Written for a broad range of environmental professionals, the
ROE provides the technical foundation for two other compo-
nents of EPA's ROE project:
• EPA's 2008 Report on the Environment: Highlights of National
Trends, which presents highlights of the ROE that EPA
believes would be of significance to the interested public.
• An electronic version of the ROE (the e-ROE, available
at http://www.epa.gov/roe), which provides online access
to printable versions of both reports, as well as to the data,
methodology, references, and sources of additional informa-
tion behind the indicators presented in the ROE.
EPA is committed to periodically updating the ROE and
its component indicators so that the latest information on
environmental status and trends is available to EPA, exter-
nal scientists, and interested members of the public on a
long-term basis.
Organization of This Report
Exhibit 1-1 provides a schematic frame-work for EPA's 2008
Report on the Environment
• The ROE: The report is organized around five main
chapters: "Air," "Water," "Land," "Human Exposure and
Health," and "Ecological Condition." These five chapters
relate to EPA's five strategic goals (Clean Air, Clean and
Safe Waters, Healthy Land, Healthy Communities and Eco-
systems, Stewardship and Compliance) and serve to focus
the ROE on issues important to EPA's mission to protect
human health and the environment.
• ROE chapters: Each chapter is organized around a set of
questions that EPA considers to be important and relevant
to its mission.
• ROE questions: For each question, the ROE:
0 Describes the issues covered by the question. These
issues include EPA's regulatory responsibilities, as well as
areas where the Agency conducts or sponsors research,
exerts policy leadership, provides information to the
public, or shares an interest in human health and the
environment with its federal, state, and tribal partners.
0 Presents indicators that are available to help answer the
question; discusses critical indicator gaps that prevent
the question from being fully answered; and reviews the
challenges to filling these gaps.
• ROE indicators: All indicators presented in the ROE
•were peer-reviewed against an indicator definition and
criteria (see Box 1-1) to ensure that they are useful, objec-
tive, transparent, and scientifically reliable. Each indica-
tor describes what the data show and any limitations that
generate uncertainty in the trend characterized by the
indicator.
Further detail on the ROE chapters, questions, and indicators
is provided below. Several sections follow the five main
ROE chapters:
• Chapter 7, "After-word," discusses the next steps for
improving indicators and summarizes the challenges to
answering the questions and synthesizing and integrating
information across indicators.
Exhibit 1-1. The ROE framework
ROE
CHAPTERS
ROE
QUESTIONS
ROE
INDICATORS
• Appendix A lists acronyms and provides a glossary of
terms that have particular definitions within this document
or \vhose definitions are not commonly available.
• Appendix B describes the process used to develop the
2008 ROE.
• Appendix C compares indicators used in the 2003 Draft
ROE Technical Document -with those in this 2008 version.
ROE Chapters
EPA has important mandates to protect air, -water, and land
(e.g., in the case of land, to ensure the safety of pesticides and
chemicals used in commerce, to ensure the reduction and
proper disposal of-wastes, and to prevent and clean up contam-
inated lands). The Agency is therefore interested in trends in
these media. In reality, however, most human health and eco-
system effects are influenced by many factors, including stres-
sors acting through multiple media and non-environmental
factors that are outside EPA's mission. EPA believes it is vitally
important to conduct surveillance of trends in indicators of
human health and ecological condition, even if they cannot
be linked -with confidence to national or regional trends in
pollutant emissions or concentrations, in order to determine
•whether they -warrant the Agency's closer attention.
1-2
EPA's 2008 Report on the Environment
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Indicator definition: For EPA's 2008 Report on the
Environment, an indicator is a numerical value derived from
actual measurements of a stressor, state or ambient condi-
tion, exposure, or human health or ecological condition
over a specified geographic domain, whose trends over time
represent or draw attention to underlying trends in the con-
dition of the environment.
Indicator criteria:
• The indicator is useful. It answers (or makes an impor-
tant contribution to answering) a question in the ROE.
• The indicator is objective. It is developed and presented
in an accurate, clear, complete, and unbiased manner.
To accommodate EPA's interest in both media-specific and
broader, more complex environmental trends, the Agency has
used the following conceptual model to organize the ROE
indicators among the chapters:
• Air, water, and land chapters (Chapters 2, 3, and 4):
The air, water, and land chapters focus on trends in these
individual media, and on resulting trends in their effects on
human health and ecological systems. An effect indicator is
included in a media chapter only if the condition or effect
can be demonstrably linked at the national level to trends
in stressors associated with that particular environmental medium.
For example, indicators of lake and stream acidity and ozone
damage to trees are placed in the air chapter (rather than
the ecological condition chapter) because trends in these
effects indicators are clearly linked to trends in the emissions
and concentration of particular air pollutants. Specifically,
downward trends in the acidity of lakes and streams in cer-
tain geologically sensitive regions of the country are clearly
linked to declining acid deposition; the type of damage
to leaves in forest plants described by the indicator can be
clearly attributed to ozone exposure. However, these indica-
tors are exceptional: the ROE's three media chapters include
very few indicators of effects, because most effects indica-
tors cannot be linked with confidence to stressors associated
•with a single environmental medium.
• Human exposure and health and ecological condi-
tion chapters (Chapters 5 and 6): These two chapters
address questions about trends in human exposure and
health and ecological condition that are influenced by
contaminants in more than one medium and by factors that
are broader than EPA's mission. For example, the human
exposure and health chapter includes a question about
trends in human disease and conditions for which environ-
mental contaminants may be a risk factor; these trends also
are influenced by other factors, such as lifestyle, genetics,
and the quality of medical care. The ecological condition
chapter includes a question about trends in diversity and
biological balance of the nation's ecological systems; these
trends are influenced not only by trends in contaminants in
multiple media but also by factors such as land use, invasive
species, and natural resource management. Trends in the
health or ecological indicators covered in Chapters 5 and
• The indicator is transparent and reproducible. The specific
data used and the specific assumptions, analytic methods,
and statistical procedures employed are clearly stated.
• The underlying data are characterized by sound collec-
tion methodologies, data management systems to protect
their integrity, and quality assurance procedures.
• Data are available to describe changes or trends and the
latest available data are timely.
• The data are comparable across time and space, and rep-
resentative of the target population. Trends depicted in
this indicator accurately represent the underlying trends
in the target population.
6 cannot be attributed with any confidence to particular
contaminants or other causes covered in the ROE's media
chapters. This is true even though epidemiological and lab-
oratory studies may have demonstrated a clear relationship
between a contaminant and a health or ecological effect.
ROE Questions
The 23 questions presented in the ROE were developed
by EPA. These are questions the Agency believes should be
answered with confidence if it is to be adequately informed
about important environmental trends; however, they are not
necessarily questions that EPA can fully answer at present based
on the indicators that meet the ROE definition and criteria.
Each question asks about environmental trends, indicating
EPA's interest in monitoring how the status of the environ-
ment and human exposure and health changes over time.
The latest data point in the trend represents the most current
information on the status of the environment or health when
the data were gathered; for some indicators, only the baseline
status is available.
ROE Indicators
Environmental conditions can be represented in many ways.
For reasons discussed below, the ROE relies on an indica-
tor approach. To maintain a high level of scientific integrity
and consistency among the indicators used in the ROE, EPA
established an explicit definition and six criteria (see Box 1-1)
that all ROE indicators must meet. The criteria are based in
part on EPA's Information Quality Guidelines (http://www.
epa.gov/quality/informationguidelines/), which cover impor-
tant information that EPA provides to the public. Together,
the six criteria are intended to ensure that all indicators in
the ROE are useful to EPA and the public, and that they are
objective, transparent, and based on high-quality, compa-
rable, and representative data across space and time. The ROE
emphasizes indicators that can be tracked over time; therefore,
one-time studies are not included unless they serve as baselines
for future trends.
The ROE indicator definition intentionally excludes some
categories of indicators. For example, ROE indicators include
measures of pollutant emissions, but not measures of more
EPA's 2008 Report on the Environment
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EPA released the first edition of the ROE as a draft report
in 2003 (see http://www.epa.gov/roe). A number of changes
have been incorporated into this 2008 edition in response
to comments on the 2003 draft. The major changes are:
• Questions: The ROE questions were revised to present
a more consistent format and comprehensive coverage of
EPA's interests across chapters.
• Indicators: The indicator definitions and criteria were
revised. As a result, several changes were made to the
2003 indicators, including combining some indicators
and deleting others. Also, new indicators have been
added that were not available for the 2003 version of the
report. See Appendix C for details.
• Indicator placement: Indicators of health or environ-
mental effects that are linked predominantly to a single
medium (air, water, land) were moved from the human
exposure and health or ecological condition chapter to
the chapter for the relevant medium.
• Spatial scale: National-level indicators were the focus
of the 2003 Draft ROE and continue to be the focus in
this 2008 ROE. However, as discussed under "Regional
Indicators," the 2008 ROE demonstrates how relevant
indicators might be identified, developed, and presented
at finer geographic scales.
general causal factors such as energy generation or agricultural
production. Also excluded are economic indicators such as
the value of land or natural resources and the cost of pollution
control, or efficiency factors such as pollutant emissions per
vehicle mile traveled. Because ROE indicators focus on actual
physical measurements, administrative indicators such as per-
mits issued, regulations promulgated, and enforcement actions
undertaken also are excluded. Indicators based on results pre-
dicted by environmental fate and transport models or risks to
people or ecological systems are excluded as well, because they
are not based on actual measurements.
Indicators, whether they represent baseline conditions or
trends, involve uncertainties. While statistical analyses could
have been presented for some of the indicators in this report,
such analyses require considerably more complex indicator
development and peer review than was possible given the time
and resource constraints for the 2008 ROE. Therefore, EPA
determined that this report would not include presentations of
statistical confidence in the status of and trends in the indica-
tors. When the word "trend" is used in an indicator, it simply
means the direction of change and does not imply statistical
significance. EPA recognizes that uncertainty is an important
issue and does plan to quantify uncertainty in future versions
of the ROE and its indicators.
EPA also recognizes that many others types of environmental
data and information are available, in addition to indicators,
that could potentially be used to answer the ROE questions.
Many environmental reports, particularly those that focus on
particular issues or locations, conduct integrated assessments
by gathering and -weighing the strengths and -weaknesses of all
the relevant information available. This integrated approach
is not feasible for the ROE because it covers so many different
topics across the entire nation.
EPA selected the indicators for this 2008 ROE based on indica-
tors suggested by EPA, other federal agencies, state agencies,
and non-governmental organizations. EPA developed a list of
proposed indicators that it believed could play a significant role
in answering the questions in the ROE. These included indica-
tors from the 2003 Draft ROE that EPA judged to be relevant
and consistent -with the 2008 ROE indicator definition and
criteria, as -well as many new indicators (see Appendix C). Indi-
cators that did not make a significant contribution to answering
the questions -were excluded from further consideration. The
time frame for developing the ROE did not allow for develop-
ment of additional indicators.
In creating this list, EPA reviewed all the indicator reports it
could find, -whether developed by EPA or others, and con-
sulted -with experts -within and outside the Agency. Generally,
EPA used existing indicators and did not invest in developing
entirely new indicators for the 2008 ROE.
The proposed indicators -were evaluated via an independent
public peer review process (see http://www.epa.gov/roe for
detailed information). Of the proposed indicators, 85 -were
ultimately selected for inclusion in the ROE. Appendix B pro-
vides more information on the indicator development process.
Each indicator consists of a graphic(s) or table(s) and explana-
tory text. All indicators present the most recent relevant,
quality-assured data available -when this report -went to press.
EPA intends to update these indicators in the e-ROE as new
data become available. The baselines and reference levels for
most indicators follow the underlying sources. Complete
documentation of the indicator data sources can be found at
http://www.epa.gov/roe. For ease of use in both the print and
e-versions, each indicator -was developed to stand alone, -with
sufficient information for the reader to understand its scope,
origin, and data sources. As a result, some redundancies of text
exist in the hardcopy version of the document.
Some indicators are used to answer more than one ROE ques-
tion. In most cases, these indicators are presented -with the
question that they are first used to answer and referenced -when
they are used to answer another question later in the ROE. For
example, the Blood Cotinine indicator is first used to answer
a question in the air chapter and then another question in the
human exposure and health chapter. The indicator is presented
in the air chapter; the human exposure and health chapter refers
the reader to the air chapter for details. Tables listing indicators
and their page numbers are provided as navigation aids at the
end of this introduction (Table 1-1), in the introduction to each
chapter, and in the introduction to each question.
1-4
EPA's 2008 Report on the Environment
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More than half of the indicators and supporting
data derive from sources other than EPA, includ-
ing other federal agencies, state agencies, and non-
governmental organizations. These external sources
also maintain many environmental data sets that are
valuable for other purposes and offer potential for
development of future ROE indicators. Many of these
data sets, though important, were not included in
this 2008 ROE because the data do not yet meet the
ROE indicator criteria. For example, since 1971, the
Centers for Disease Control and Prevention (CDC),
EPA, and the Council of State and Territorial Epide-
miologists have maintained a surveillance system for
collecting and periodically reporting data on occur-
rences and causes of waterborne disease outbreaks
(WBDOs). These surveillance activities are useful in
characterizing the epidemiology of WBDOs, iden-
tifying changing trends in the etiologic agents that
cause WBDOs, and determining why the outbreaks
occurred. However, because of several limitations,
including under-reporting and differences in how
states investigate and report outbreaks, these data do
not currently meet the ROE criteria for an indicator.
EPA continues to work with CDC and other federal,
state, and private organizations on important programs such
as this one, so that they may meet the indicator criteria and be
used in future editions of the ROE.
Regional Indicators
The ROE focuses on trends within the U.S., even though the
indicators may be affected by sources outside U.S. borders.
National-level indicators (indicators for which nationally con-
sistent data are available) are the focus of this report. However,
highly aggregated national data may mask important varia-
tions that take place at finer scales. Therefore, the ROE takes
two preliminary steps to demonstrate how indicators might be
identified, developed, and presented at finer geographic scales.
• National data are broken out by major geographic region for
32 indicators for which the data are sufficiently representative
at that geographic scale. Rather than adopt regionalization
schemes based on natural boundaries that would not be
consistent among indicators, and because EPA Regions play
an important role in the way EPA's environmental protec-
tion efforts are implemented, EPA chose to use EPA Regions
for the 25 indicators where this was possible. EPA Regions
follow state borders and do not reflect natural boundaries
based on physiography, climate, or biota. To aid readers who
are unfamiliar with EPA Regional boundaries, the ten EPA
Regions are delineated in Exhibit 1-2, and also depicted in
icons on each indicator graphic that displays regional data.
• Eight Regional Indicators (indicators that cover an EPA
Region or substantial parts of one or more EPA Regions) were
selected to demonstrate how such indicators can answer part
of an ROE question that is unique to a particular Region, or
could eventually be expanded to answer an ROE question at
the national level. Like the National Indicators, all Regional
Indicators were peer-reviewed against the ROE indicator
definition and criteria. EPA hopes that the Regional Indicators
libit 1-2. The EPA Regions
•will serve as useful models, and that lessons learned from them
•will help the Agency identify and present a more robust set
of indicators that answer ROE questions at multiple scales in
the future. However, it is important to note that the Regional
Indicators are presented as examples only: trends in these indica-
tors are not necessarily representative of similar trends in other
regions or in the nation as a whole; they do not represent an
exclusive set of indicators needed to answer the ROE ques-
tions at a regional scale; and they may or may not scale up to
National Indicators. EPA may or may not include these indica-
tors in future versions of the ROE.
Conclusion
The Report on the Environment represents a commitment by EPA
to continually improve the quality and quantity of information
available to understand the condition of human health and the
environment and how it is changing over time. Within EPA,
this commitment provides ongoing opportunities to use the
ROE to inform strategic planning and related activities. The
ROE also creates opportunities to establish and strengthen
partnerships among federal, state, tribal, and non-governmental
organizations for monitoring, data sharing, and data needs
planning to support indicator development and improvement.
As mentioned earlier, the topics of air, water, land, human
exposure and health, and ecological condition under which the
indicators are presented are all interconnected. Changes in one
medium affect other media; human health is affected by envi-
ronmental condition; and environmental condition is affected
by human factors. In reality, humans and ecological systems are
exposed to multiple pollutants from multiple sources; large spa-
tial and temporal variations in environmental exposures exist;
and numerous non-environmental factors also have influence.
EPA recognizes these complexities; to improve future versions
of the ROE, EPA will continue to seek ways to better link and
integrate indicators across questions and chapters.
EPA's 2008 Report on the Environment
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Table 1-1. ROE Questions and Supporting Indicators1
Air Chapter Section
Page
Outdoor Air Quality
What are the trends in outdoor air quality and their effects on human health
and the environment?
Carbon Monoxide Emissions
Ambient Concentrations of Carbon Monoxide
Lead Emissions
Ambient Concentrations of Lead
Nitrogen Oxides Emissions
Ambient Concentrations of Nitrogen Dioxide
Volatile Organic Compounds Emissions
Ambient Concentrations of Ozone
Ozone Injury to Forest Plants
Particulate Matter Emissions
Ambient Concentrations of Particulate Matter
Regional Haze
Sulfur Dioxide Emissions
Acid Deposition
Lake and Stream Acidity
Percent of Days with Air Quality Index Values Greater Than 100
Mercury Emissions
Air Toxics Emissions
Ambient Concentrations of Benzene
Concentrations of Ozone-Depleting Substances
Ozone Levels over North America
Ozone and Particulate Matter Concentrations for U.S. Counties in the
U.S./Mexico Border Region
Ambient Concentrations of Manganese Compounds in EPA Region 5
2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2-6
2-9
2-11
2-12
2-14
2-16
2-18
2-20
2-22
2-24
2-26
2-29
2-33
2-34
2-37
2-42
2-44
2-46
2-48
2-51
2-52
2-54
2-56
2-58
Greenhouse Gases
What are the trends in greenhouse gas emissions and concentrations?
U.S. Greenhouse Gas Emissions
Atmospheric Concentrations of Greenhouse Gases
2.3
2.3.2
2.3.2
2-62
2-64
2-66
1 As mentioned earlier, some indicators are used to answer more than one question. In most cases, these indicators are presented where they are first used to answer
a question and referenced under subsequent questions.
1-6
EPA's 2008 Report on the Environment
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Table 1-1. ROE Questions and Supporting Indicators (continued)
Air Chapter (continued) Section
Page
Indoor Air Quality
What are the trends in indoor air quality and their effects on human health?
U.S. Homes Above EPA's Radon Action Level
Blood Cotinine Level
2.4
2.4.2
2.4.2
Water Chapter Section
2-73
2-74
2-76
Page
Water and Watersheds
What are the trends in the extent and condition of fresh surface waters and
their effects on human health and the environment?
High and Low Stream Flows
Streambed Stability in Wadeable Streams
Lake and Stream Acidity
Nitrogen and Phosphorus in Wadeable Streams
Nitrogen and Phosphorus in Streams in Agricultural Watersheds
Nitrogen and Phosphorus Loads in Large Rivers
Pesticides in Streams in Agricultural Watersheds
Benthic Macroinvertebrates in Wadeable Streams
3.2
3.2.2
3.2.2
2.2.2
3.2.2
3.2.2
3.2.2
3.2.2
3.2.2
3-6
3-8
3-11
2-42
3-13
3-15
3-17
3-19
3-21
Ground Water
What are the trends in the extent and condition of ground water and their
effects on human health and the environment?
Nitrate and Pesticides in Shallow Ground Water in Agricultural Watersheds
3.3
3.3.2
3-25
3-27
Wetlands
What are the trends in the extent and condition of wetlands and their effects
on human health and the environment?
Wetland Extent, Change, and Sources of Change
3.4
3.4.2
3-30
3-32
Coastal Waters
What are the trends in the extent and condition of coastal waters and their
effects on human health and the environment?
Wetland Extent, Change, and Sources of Change
Trophic State of Coastal Waters
Coastal Sediment Quality
Coastal Benthic Communities
Coastal Fish Tissue Contaminants
Submerged Aquatic Vegetation in the Chesapeake Bay
Hypoxia in the Gulf of Mexico and Long Island Sound
3.5.2
3.4.2
3.5.2
3.5.2
3.5.2
3.8.2
3.5.2
3.5.2
3-35
3-32
3-38
3-42
3-44
3-61
3-46
3-48
EPA's 2008 Report on the Environment
1-7
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Table 1-1. ROE Questions and Supporting Indicators (continued)
Water Chapter (continued)
Drinking Water
What are the trends in the quality of drinking water and their effects on
human health?
Population Served by Community Water Systems with No Reported
Violations of Health-Based Standards
Recreational Water
What are the trends in the condition of recreational waters and their effects
on human health and the environment?
Consumable Fish and Shellfish
What are the trends in the condition of consumable fish and shellfish and
their effects on human health?
Coastal Fish Tissue Contaminants
Contaminants in Lake Fish Tissue
Land Chapter
Land Cover
What are the trends in land cover and their effects on human health and the
environment?
Land Cover
Forest Extent and Type
Land Cover in the Puget Sound/Georgia Basin
What are the trends in land use and their effects on human health and the
environment?
Land Use
Urbanization and Population Change
What are the trends in wastes and their effects on human health and the
environment?
Quantity of Municipal Solid Waste Generated and Managed
Quantity of RCRA Hazardous Waste Generated and Managed
Chemicals Used on the Land
What are the trends in chemicals used on the land and their effects on
human health and the environment?
Fertilizer Applied for Agricultural Purposes
Toxic Chemicals in Production-Related Wastes Combusted for Energy
Recovery, Released, Treated, or Recycled
Pesticide Residues in Food
Reported Pesticide Incidents
Section
3.6
3.6.2
3.7
3.8.2
3.8.2
Section
4.2
4.2.2
6.2.2
4.2.2
•
4.3
4.3.2
4.3.2
•
4.4
4.4.2
4.4.2
•
4.5
4.5.2
4.5.2
4.5.2
4.5.2
3-52
3-54
3-57
3-59
3-61
3-63
4-5
4-7
6-8
4-10
•
4-13
4-14
4-19
•
4-23
4-24
4-26
•
4-29
4-30
4-33
4-37
4-39
1-8
EPA's 2008 Report on the Environment
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Table 1-1. ROE Questions and Supporting Indicators (continued)
Land Chapter (continued)
Contaminated Land
Section
What are the trends in contaminated land and their effects on human health
and the environment?
Current Human Exposures Under Control at High-Priority Cleanup Sites
Migration of Contaminated Ground Water Under Control at High-Priority
Cleanup Sites
4.6
4.6.2
4.6.2
Human Exposure and Health Chapter Section
4-42
4-44
4-47
Page
Exposure to Environmental Contaminants
What are the trends in human exposure to environmental contaminants,
including across population subgroups and geographic regions?
Blood Lead Level
Blood Mercury Level
Blood Cadmium Level
Blood Persistent Organic Pollutants Level
Blood Cotinine Level
Urinary Pesticide Level
Urinary Phthalate Level
5.2
5.2.2
5.2.2
5.2.2
5.2.2
2.4.2
5.2.2
5.2.2
5-7
5-10
5-12
5-13
5-15
2-76
5-22
5-26
Health Status
What are the trends in health status in the United States?
General Mortality
Life Expectancy at Birth
Infant Mortality
Disease and Conditions
What are the trends in human disease and conditions for which
environmental contaminants may be a risk factor, including across
population subgroups and geographic regions?
Cancer Incidence
Childhood Cancer Incidence
Cardiovascular Disease Prevalence and Mortality
Chronic Obstructive Pulmonary Disease Prevalence and Mortality
Asthma Prevalence
Infectious Diseases Associated with Environmental
Exposures or Conditions
Birth Defects Prevalence and Mortality
Low Birthweight
Preterm Delivery
5.3
5.3.2
5.3.2
5.3.2
5.4
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5-31
5-33
5-35
5-36
5-39
5-43
5-46
5-48
5-52
5-55
5-59
5-62
5-65
5-67
EPA's 2008 Report on the Environment
1-9
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Table 1-1. ROE Questions and Supporting Indicators (continued)
Ecological Condition Chapter Section
Page
Extent and Distribution
What are the trends in the extent and distribution of the nation's
ecological systems?
Land Cover
Forest Extent and Type
Forest Fragmentation
Wetland Extent, Change, and Sources of Change
Land Use
Urbanization and Population Change
Land Cover in the Puget Sound/Georgia Basin
Ecological Connectivity in EPA Region 4
Relative Ecological Condition of Undeveloped Land in EPA Region 5
6.2
4.2.2
6.2.2
6.2.2
3.4.2
4.3.2
4.3.2
4.2.2
6.2.2
6.2.2
6-7
4-7
6-8
6-11
3-32
4-14
4-19
4-10
6-13
6-14
Diversity and Biological Balance
What are the trends in the diversity and biological balance of the nation's
ecological systems?
Coastal Benthic Communities
Benthic Macroinvertebrates in Wadeable Streams
Bird Populations
Fish Faunal Intactness
Submerged Aquatic Vegetation in the Chesapeake Bay
Non-Indigenous Benthic Species in the Estuaries of the Pacific Northwest
6.3
3.5.2
3.2.2
6.2.2
6.2.2
3.5.2
6.2.2
6-18
3-44
3-21
6-20
6-21
3-46
6-23
Ecological Processes
What are the trends in the ecological processes that sustain the
nation's ecological systems?
Carbon Storage in Forests
6.4
6.4.2
affiffifnl
What are the trends in the critical physical and chemical attributes
of the nation's ecological systems?
U.S. and Global Mean Temperature and Precipitation
Sea Surface Temperature
Streambed Stability in Wadeable Streams
High and Low Stream Flows
Sea Level
Nitrogen and Phosphorus Loads in Large Rivers
Nitrogen and Phosphorus in Wadeable Streams
6.5
6.5.2
6.5.2
3.2.2
3.2.2
6.5.2
3.2.2
3.2.2
6-27
6-28
^^H
6-31
6-32
6-37
3-11
3-8
6-39
3-17
3-13
1-10
EPA's 2008 Report on the Environment
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Table 1-1. ROE Questions and Supporting Indicators (continued)
Ecological Condition Chapter (continued)
Physical and Chemical Attributes (continued)
What are the trends in the critical physical and chemical attributes
of the nation's ecological systems? (continued)
Nitrogen and Phosphorus in Streams in Agricultural Watersheds
Lake and Stream Acidity
Hypoxia in the Gulf of Mexico and Long Island Sound
Section
6.5
3.2.2
2.2.2
3.5.2
Ecological Exposure to Contaminants
What are the trends in biomarkers of exposure to common environmental
contaminants in plants and animals?
Coastal Fish Tissue Contaminants
Contaminants in Lake Fish Tissue
Ozone Injury to Forest Plants
6.6
3.8.2
3.8.2
2.2.2
6-31
3-15
2-42
3-48
•
6-45
3-61
3-63
2-24
EPA's 2008 Report on the Environment
1-11
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Chapter 2
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Contents
2.1 Introduction 2-3
2.1.1 Overview of the Data 2-4
2.1.2 Organization of This Chapter 2-5
2.2 What Are the Trends in Outdoor Air Quality and Their Effects on Human
Health and the Environment? 2-6
2.2.1 Introduction 2-6
2.2.2 ROE Indicators 2-7
2.2.3 Discussion 2-60
2.3 What Are the Trends in Greenhouse Gas Emissions and Concentrations? 2-62
2.3.1 Introduction 2-62
2.3.2 ROE Indicators 2-63
2.3.3 Discussion 2-72
2.4 What Are the Trends in Indoor Air Quality and Their Effects on Human Health? 2-73
2.4.1 Introduction 2-73
2.4.2 ROE Indicators 2-74
2.4.3 Discussion 2-79
-------
2.1 Introduction
ir provides the oxygen and carbon dioxide needed to
sustain human, animal, and plant life on Earth, and the
composition of trace gases in the atmosphere plays an
important role for the climate. Air pollution can adversely affect
these critical functions of the atmosphere in many ways. High
levels of air pollution, whether indoors or outdoors, can harm
human health by triggering asthma attacks, aggravating aller-
gies, and contributing to or potentially causing various diseases.
Certain types of outdoor air pollution can impair visibility and
damage other valued resources, such as forests, lakes and streams,
and building surfaces. On a global scale, air pollution released
worldwide can eventually change the atmosphere's composition
\vith important consequences, including depletion of the Earth's
ozone layer and climate change.
An important component of EPA's mission is to protect and
improve air quality in order to avoid or mitigate the conse-
quences of air pollution's harmful effects. State and tribal air
pollution control agencies help fulfill this mission by imple-
menting many of the air pollution control requirements that
EPA sets at the federal level. Other federal partners, the aca-
demic community, industry and trade associations, and non-
governmental organizations all conduct important research
that contributes to the current understanding of regional,
national, and global air quality issues.
Efforts to maintain good air quality are complicated by popula-
tion increase, energy consumption, motor vehicle use, and other
factors that can lessen air quality. Outdoor air is polluted by
emissions from a broad array of industrial and mobile sources, as
•well as everyday activities like dry cleaning, painting, and refu-
eling vehicles. Emissions from natural sources, such as wildfires,
also contribute to outdoor air pollution. Similarly, indoor air
quality is affected not only by these outdoor sources, but also by
sources found within buildings, such as home heating devices,
tobacco smoke, consumer products, and building materials. In
this chapter, EPA assesses national trends in the condition of air,
stressors that influence air quality, and associated exposures and
effects among humans and ecological systems. ROE indicators
are presented to address three fundamental questions about the
state of the nation's air:
• What are the trends in outdoor air quality and their
effects on human health and the environment? This
question examines a broad spectrum of outdoor air quality
issues, including polluted air that people breathe at ground
level, deposition of air pollutants to land and water, and
depletion of the Earth's ozone layer. For each issue, infor-
mation is provided both on the main stressors (emissions
sources) and potential health and environmental effects.
• What are the trends in greenhouse gas emissions and
concentrations? This question focuses on releases and
atmospheric concentrations of certain so-called "green-
house gases," or gases in the atmosphere that help regulate
the Earth's temperature and thus contribute to climate
change—a topic introduced in this chapter and revisited in
Chapter 6, "Ecological Condition."
EPA's 2008 Report on the Environment (ROE): Essentials
ROE Approach
This 2008 Report on the Environment:
• Asks questions that EPA considers
important to its mission to protect
human health and the environment.
• Answers these questions, to the extent
possible, with available indicators.
• Discusses critical indicator gaps, limita-
tions, and challenges that prevent the
questions from being fully answered.
ROE Questions
The air, water, and land chapters (Chapters
2, 3, and 4) ask questions about trends in
the condition and/or extent of the envi-
ronmental medium; trends in stressors to
the medium; and resulting trends in the
effects of the contaminants in that medium
on human exposure, human health, and
the condition of ecological systems.
The human exposure and health and
ecological condition chapters (Chapters
5 and 6) ask questions about trends in
aspects of health and the environment
that are influenced by many stressors
acting through multiple media and by
factors outside EPA's mission.
ROE Indicators
An indicator is derived from actual mea-
surements of a pressure, state or ambient
condition, exposure, or human health or
ecological condition over a specified geo-
graphic domain. This excludes indicators
such as administrative, socioeconomic, and
efficiency indicators.
Indicators based on one-time studies are
included only if they were designed to serve
as baselines for future trend monitoring.
All ROE indicators passed an independent
peer review against six criteria to ensure
that they are useful; objective; transparent;
and based on data that are high-quality,
comparable, and representative across space
and time.
Most ROE indicators are reported at the
national level. Some national indicators
also report trends by region. EPA Regions
were used, where possible, for consistency
and because they play an important role in
how EPA implements its environmental
protection efforts.
Several other ROE indicators describe
trends in particular regions as examples of
how regional indicators might be included
in future versions of the ROE. They are
not intended to be representative of trends
in other regions or the entire nation.
EPA will periodically update and revise
the ROE indicators and add new indicators
as supporting data become available. In the
future, indicators will include information
about the statistical confidence of status
and trends. Updates will be posted elec-
tronically at http://www.epa.gov/roe.
Additional Information
You can find additional information about
the indicators, including the underlying
data, metadata, references, and peer review,
at http://www.epa.gov/roe.
EPA's 2008 Report on the Environment
2-3
-------
• What are the trends in indoor air quality and their
effects on human health? This question considers air
quality in indoor settings, such as homes, offices, and
schools, and how poor indoor air quality can affect human
health and welfare, whether by causing adverse health
effects or by impairing productivity.
These ROE questions are posed without regard to whether
indicators are available to answer them. This chapter presents
the indicators available to answer these questions, and also
points out important gaps where nationally representative data
are lacking.
While this chapter focuses on air quality, readers should not
infer that air quality trends are completely independent of
the other themes in ROE: water, land, human exposure and
health, and ecological condition. High levels of air pollution
are linked to many broader environmental concerns. Because
air interfaces directly with water and land, air pollutants can
enter these media through various fate and transport mecha-
nisms, such as wet deposition into surface waters, dry depo-
sition of gaseous pollutants, and gravitational settling onto
soils, vegetation, and other surfaces. Conversely, chemicals in
surface water and soil can enter outdoor air through processes
like evaporation and resuspension of wind-blown dust. Thus,
in a very general sense, air quality is related to selected topics
covered in the water chapter and the land chapter. Further,
nearly every topic addressed in this chapter is primarily moti-
vated by some specific concern regarding human health or
ecological effects. Therefore, air quality and climate change
are conceptually linked to many topics addressed in the
human exposure and health and ecological condition chapters.
Air quality issues that are connected with other ROE themes
are introduced and examined in this chapter, and addressed
further in later sections of the ROE as appropriate.
2.1.1 Overview of the Data
When developing the 27 ROE indicators in this chapter, EPA
accessed and compiled data collected by many parties. The
individual data sources that were evaluated can be classified
into four general categories:
• National emissions inventories. Emissions data were
queried from databases known as emissions inventories.
These inventories are composites of measured and esti-
mated emission rates for industrial sources, mobile sources,
area sources, and natural sources. Industry and state, tribal,
and local agencies provide most of the data compiled in
these inventories.
• Ground-level ambient air monitoring data. Ambient
air concentrations measured at ground level primarily come
from measurements collected in a nation-wide net-work of
ambient air monitoring stations (i.e., the State and Local
Air Monitoring Stations net-work, other special purposes
monitors). State, tribal, and local agencies operate most
of these stations and submit their validated measurement
results to a centralized database.
• Deposition measurements. Data on deposition of
outdoor air pollutants come from samples collected and
analyzed at fixed locations throughout the country as part
of the National Atmospheric Deposition Program and the
Clean Air Status and Trends Net-work.
• Other data sources. The remaining ROE indicators in
this chapter draw from various other data sources, includ-
ing satellite measurements of stratospheric ozone depletion,
an evaluation of pollution-related injury to forest plants,
surveys on radon in homes and evidence of exposure to
environmental tobacco smoke, an inter-agency assessment
of regional haze, and articles in the peer-reviewed literature
on historical concentrations of greenhouse gases estimated
from ice core samples.
Tracking the country's air quality is a complicated endeavor
and cannot be done -with any single indicator. Multiple indica-
tors are needed to characterize indoor air quality separately
from outdoor air quality, air quality trends at ground level
separately from changing atmospheric conditions aloft, and air
pollution levels for the many different pollutants of potential
concern. Regardless of the issue of interest, a particular chal-
lenge in developing this chapter's indicators is that air quality
can vary considerably -with location and time. Consequently,
all underlying data sources must be sufficiently representative,
both spatially and temporally.
Spatial resolution is a critical consideration due to associated
spatial variations in population density, industrial emissions
sources, traffic patterns, and meteorological conditions that
dictate relevant atmospheric fate and transport processes. Tem-
poral resolution also must be considered because ambient air
concentrations of certain pollutants vary considerably -with time
of day (partly due to sunlight's contribution to photochemical
reactions and due to variations in dilution), day of-week (partly
due to changes in commuting patterns), and season (mostly due
to changes in meteorological conditions). Temporal resolution is
particularly important -when interpreting air quality trends: long
enough time frames must be considered to ensure that trends
reflect sustained changes in air quality, rather than natural fluc-
tuations in atmospheric conditions.
This chapter presents only data that meet the ROE indicator
definition and criteria (see Box 1-1, p. 1-3). Note that non-
scientific indicators, such as administrative and economic
indicators, are not included in this definition. Thorough doc-
umentation of the indicator data sources and metadata can be
found online at http://www.epa.gov/roe. All indicators -were
peer-reviewed during an independent peer review process
(again, see http://www.epa.gov/roe for more information).
Readers should not infer that the indicators included reflect
the complete state of knowledge on the nation's air. Many
other data sources, publications, and site-specific research
projects have contributed substantially to the current under-
standing of air quality trends, but are not used in this report
because they did not meet some aspect of the ROE indicator
criteria.
2-4
EPA's 2008 Report on the Environment
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2.1.2 Organization of
This Chapter
This chapter's remaining three sections are framed around
the three overarching questions that EPA seeks to answer
about trends in air. Each section introduces the question and
its importance, presents the National Indicators that help
answer the question, and discusses what these indicators, taken
together, say about the question. The chapter also presents two
Regional Indicators that meet the ROE indicator definition
and criteria and help to answer a question at a smaller geo-
graphic scale. Each section concludes by listing major chal-
lenges to answering the questions and identifying important
data gaps.
Table 2-1 lists the indicators used to answer the three ques-
tions in this chapter and shows the locations where the indica-
tors are presented.
Table 2-1. Air—ROE Questions and Indicators
Question Indicator Name Section
What are the trends
in outdoor air quality
and their effects on
human health and the
environment?
What are the trends in
greenhouse gas emissions
and concentrations?
What are the trends in
indoor air quality and their
effects on human health?
Carbon Monoxide Emissions (N/R)
Ambient Concentrations of Carbon Monoxide (N/R)
Lead Emissions (N)
Ambient Concentrations of Lead (N)
Nitrogen Oxides Emissions (N/R)
Ambient Concentrations of Nitrogen Dioxide (N/R)
Volatile Organic Compounds Emissions (N/R)
Ambient Concentrations of Ozone (N/R)
Ozone Injury to Forest Plants (N/R)
Particulate Matter Emissions (N/R)
Ambient Concentrations of Particulate Matter (N/R)
Regional Haze (N)
Sulfur Dioxide Emissions (N/R)
Acid Deposition (N)
Lake and Stream Acidity (N)
Percent of Days with Air Quality Index Values Greater Than 100 (N/R)
Mercury Emissions (N)
Air Toxics Emissions (N/R)
Ambient Concentrations of Benzene (N)
Concentrations of Ozone-Depleting Substances (N)
Ozone Levels over North America (N)
Ozone and Particulate Matter Concentrations for U.S. Counties in the
U.S./Mexico Border Region (R)
Ambient Concentrations of Manganese Compounds in EPA Region 5 (R)
U.S. Greenhouse Gas Emissions (N)
Atmospheric Concentrations of Greenhouse Gases (N)
U.S. Homes Above EPA's Radon Action Level (N)
Blood Cotinine Level (N)
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.3.2
2.3.2
2.4.2
2.4.2
Page
2-9
2-11
2-12
2-14
2-16
2-18
2-20
2-22
2-24
2-26
2-29
2-33
2-34
2-37
2-42
2-44
2-46
2-48
2-51
2-52
2-54
2-56
2-58
2-64
2-66
2-74
2-76
N = National Indicator
R = Regional Indicator
N/R = National Indicator displayed at EPA Regional scale
EPA's 2008 Report on the Environment
2-5
-------
2.2 What Are the Trends
in Outdoor Air Quality
and Their Effects on
Human Health and the
Environment?
2.2.1 Introduction
Outdoor air—the air outside buildings, from ground level to
several miles above the Earth's surface—is a valuable resource
for current and future generations because it provides essen-
tial gases to sustain life and it shields the Earth from harmful
radiation. Air pollution can compromise outdoor air quality in
many ways. Outdoor air pollution, for instance, is associated
•with various adverse health effects including asthma attacks
and cancer; outdoor air pollution can also contribute to "acid
rain," damage crops and surfaces of treasured buildings and
monuments, and diminish the protective ozone layer in the
upper atmosphere. Maintaining clean air is a challenging task,
especially considering the growing stressors on outdoor air
quality such as increased population growth, increased use of
motor vehicles, and increased energy consumption.
Outdoor air pollution contains numerous substances of both
natural and anthropogenic origin. While natural sources
release some potentially harmful substances into the air (e.g.,
pollen, mold spores, dust), emissions sources of anthropogenic
origin are of particular interest because regulatory and volun-
tary reductions can lead to decreased emissions and associated
air quality improvements. Accordingly, this section focuses
on outdoor air quality issues caused at least in part by human
activity and acknowledges and quantifies contributions from
natural sources, as appropriate.
Most outdoor air quality issues can be traced back to emissions
sources that release pollutants into the air. Emissions sources
are typically classified into different categories, such as point
sources (e.g., power plants, industrial facilities), area sources
(e.g., air pollution sources over a diffuse area, such as gasoline
stations and dry cleaners), mobile sources (e.g., cars, trucks,
airplanes, off-road vehicles), and natural sources (e.g., wildfires,
wind-blown dust, volcanoes, vegetation). Once pollutants are
airborne, prevailing wind patterns carry and disperse them
from their sources to other locations. Atmospheric chemical
reactions may consume some airborne pollutants and create
others. As pollutants mix in the atmosphere, depending on
their chemical and physical properties, some pollutants deposit
to the Earth's surface near their sources, while others remain
airborne for hours, days, or years. Deposition of air pollut-
ants, especially those that are persistent and bioaccumulative,
can lead to accumulation of contaminants in other media. The
levels of air pollution at a given location and at a given time are
influenced by emissions from nearby and distant sources as well
as by atmospheric factors, such as meteorology.
Human exposure to outdoor air pollution is a function of the
composition and magnitude of air pollution, combined with
human activity patterns. Ambient concentration data, while
useful for characterizing outdoor air quality, ultimately do not
quantify exposures, because ambient air monitoring equip-
ment measures air quality at fixed outdoor locations, while
people breathe air in multiple indoor and outdoor environs
throughout a day. Whether people are harmed by poor air
quality depends on the mixture of pollutants found in the air,
exposure doses and durations, individuals' susceptibilities to
diseases, and other factors. Similarly, air pollutants' interac-
tions with ecosystems determine whether air pollution causes
harmful environmental effects. For a complete understanding
of a given air pollution issue, information is therefore typi-
cally sought on emissions sources, ambient air concentrations,
exposures, and effects.
Outdoor air pollution can contain hundreds of different pollut-
ants, which are typically grouped into various categories based
on shared attributes. Some categories are defined by pollutants'
physical attributes (e.g., gases, particulate matter), while others
by regulatory terminology (e.g., criteria pollutants, air toxics).
The indicators used to answer the question regarding outdoor
air quality are organized into the following three categories,
which were selected based on the different parts of the atmo-
sphere to which they pertain and the different types of infor-
mation available to support indicator development:
• Criteria pollutants. The following six common pollutants
are referred to as criteria pollutants: carbon monoxide, lead,
nitrogen dioxide, ozone, particulate matter of different size
fractions, and sulfur dioxide. These pollutants are known
as "criteria pollutants" because EPA regulates them by
developing human health-based or environmentally based
criteria (or science-based guidelines) for setting permis-
sible levels. Specifically, the Clean Air Act requires EPA
to set National Ambient Air Quality Standards (NAAQS)
for these pollutants that are commonly found in outdoor
air and can harm human health or the environment. The
NAAQS have been modified and, in some cases, revoked
since they were originally established. EPA is required to
periodically review and update the NAAQS to reflect the
latest scientific information on how outdoor air quality
affects human health and the environment. Extensive data
are available on criteria pollutants' emissions (or emissions
of the pollutants' precursors) and ambient concentrations.
• Air toxics and other air pollutants. Air toxics, also
known as hazardous air pollutants, are known or suspected
to cause cancer and are associated with other serious health
effects, such as reproductive effects or birth defects, or
adverse environmental effects. The Clean Air Act specifi-
cally identifies 188 air toxics. Numerous other air pollutants
exhibit toxicity even though they are not classified as air
toxics; included among these other pollutants are several
hundred chemicals whose emissions are tracked in EPA's
Toxics Release Inventory.
2-6
EPA's 2008 Report on the Environment
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• Stratospheric ozone issues. The ozone layer occurs in
the stratosphere between 6 and 20 miles above the Earth's
surface and protects the Earth's biota from harmful effects
of the sun's ultraviolet radiation. Past and ongoing releases
of a number of synthetic chemicals from throughout
the world have depleted the ozone layer, allowing more
ultraviolet radiation to reach the Earth's surface. This can
lead to increased incidence of skin cancer, cataracts, and
other health problems.1 Further, high levels of ultraviolet
radiation can cause detrimental ecological effects, such as
stressing productivity of marine phytoplankton, which are
essential components of the oceanic food web.2
Air pollution is manifest over a range of spatial and temporal
domains—an important factor to consider when evaluating
trends for the three categories considered in this section. The
spatial domains of air pollution issues vary widely. Air pollu-
tion can be local in nature. For instance, ambient concentra-
tions of benzene tend to be greatest in the proximity of major
sources (e.g., oil refineries, chemical production facilities) and in
high-traffic areas; long-range transport is relatively unimportant
due to benzene's photochemical reactivity and the dilution that
occurs over longer distances. Air pollution can also extend over
regional and national scales. For example, emissions sources
hundreds of miles away can contribute to airborne fine par-
ticulate matter at a given location.3 Finally, a few air pollution
issues are global in nature, such as intercontinental transport
of particles during dust storms. Stratospheric ozone depletion,
as another example, is affected by releases of ozone-depleting
substances from countries worldwide. The spatial domains ulti-
mately determine the minimum spatial resolution of monitors
needed to adequately characterize trends.
Temporal scales also vary among pollutants and typically reflect
some combination of changes in emissions and fluctuations
in weather. Ambient air concentrations of some air pollut-
ants, like ground-level ozone, have considerable diurnal and
seasonal variations.4 However, temporal variations are far less
pronounced for pollutants that are long-lived in the atmo-
sphere, including many ozone-depleting substances. Tempo-
ral variations largely determine the appropriate monitoring
frequency for quantifying trends and the most meaningful
statistic (or averaging time) used to report ambient air concen-
trations. When quantifying and interpreting long-term trends
in outdoor air quality, attention also must be paid to changes
in emissions estimation techniques and advances in ambient air
monitoring technologies. Unless other-wise noted, the outdoor
air quality indicators only come from data sets generated using
consistent methodologies over the entire time frame of interest.
The nation-wide air quality trends in this section are generally
consistent -with those documented in other EPA publications,
though readers should not expect to find perfect concor-
dance among individual data points. This is because some
publications address different spatial domains or time frames
and may use less rigorous selection criteria -when identifying
and compiling data sets.
2.2.2 ROE Indicators
The 23 outdoor air quality indicators track emissions, ambi-
ent concentrations, and pollution-related effects over varying
spatial domains and time spans, depending on the availability
of underlying data. The indicators include 21 National Indica-
tors (12 of-which break national data down into the ten EPA
Regions) and two Regional Indicators. The most extensive
temporal coverage of these indicators tracks trends from 1964
to the present.
Indicators -were developed using data compiled from multiple
sources. Emissions indicators are based on EPA's National
Emissions Inventory (NEI), a database of measured and esti-
mated emissions for numerous pollutants and source catego-
ries. At the -writing of this report, NEI data -were available for
1990 through 2002, but the indicators only present data for
those inventory years that are fully updated and are developed
using consistent methodologies. Ground-level ambient air
concentration indicators -were developed from data in EPA's
Air Quality System (AQS), a clearinghouse of validated ambi-
ent air monitoring results submitted largely by tribal, state,
and local environmental agencies. The ambient concentration
indicators present data through calendar year 2006, -which is
the most recent calendar year having a complete, validated
set of monitoring data available from AQS -when this report
•was prepared. Remaining indicators draw from different
monitoring programs, including regional haze data from the
Interagency Monitoring of Protected Visual Environments,
acid deposition measurements from the multi-agency National
Atmospheric Deposition Program and Clean Air Status and
Trends Net-work, ozone injury observations from the U.S.
Forest Service's Forest Health Monitoring Program, and
monitoring of stratospheric ozone levels and concentrations of
ozone-depleting substances conducted by the National Oce-
anic and Atmospheric Administration.
Table 2-2 shows how indicators are classified into three gen-
eral categories (criteria pollutants, air toxics and other pollut-
ants, stratospheric ozone issues) and then further organized by
pollutant. For each pollutant and to the extent supported by
ROE indicators, relevant emissions indicators are presented
first, immediately followed by ambient concentration indica-
tors, and next by effects indicators. With this organization,
readers can readily compare trends in emissions, ambient
concentrations, and effects for the same pollutant.
World Meteorological Organization. 2007. Scientific assessment of ozone
depletion: 2006. Geneva, Switzerland.
DeMora, S., S. Demers, and M.Vernet. 2000.The effects of UV radiation in
the marine environment. Cambridge, United Kingdom: Cambridge Univer-
sity Press.
US. Environmental Protection Agency. 2004. The particle pollution
report: Current understanding of air quality and emissions through 2003.
EPA/454/R-04/002. Research Triangle Park, NC.
U.S. Environmental Protection Agency. 2004. The ozone report: Measuring
progress through 2003. EPA/454/K-04/001. Research Triangle Park, NC.
EPA's 2008 Report on the Environment
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Table 2-2. ROE Indicators of Trends in Outdoor Air Quality and Their Effects
on Human Health and the Environment
National Indicators
Section
Page
Criteria Pollutants and Their Precusors
Carbon Monoxide Emissions (N/R)
Ambient Concentrations of Carbon Monoxide (N/R)
Lead Emissions
Ambient Concentrations of Lead
Nitrogen Oxides Emissions (N/R)
Ambient Concentrations of Nitrogen Dioxide (N/R)
Volatile Organic Compounds Emissions (N/R)
Ambient Concentrations of Ozone (N/R)
Ozone Injury to Forest Plants (N/R)
Particulate Matter Emissions (N/R)
Ambient Concentrations of Particulate Matter (N/R)
Regional Haze
Sulfur Dioxide Emissions (N/R)
Acid Deposition
Lake and Stream Acidity
Percent of Days with Air Quality Index Values Greater Than 100 (N/R)
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2.2.2
2-9
2-11
2-12
2-14
2-16
2-18
2-20
2-22
2-24
2-26
2-29
2-33
2-34
2-37
2-42
2-44
Air Toxics and Other Pollutants
Mercury Emissions
Air Toxics Emissions (N/R)
Ambient Concentrations of Benzene
2.2.2
2.2.2
2.2.2
2-46
2-48
2-51
Stratospheric Ozone Issues
Concentrations of Ozone-Depleting Substances
Ozone Levels over North America
Regional Indicators
2.2.2
2.2.2
Section
Ozone and Particulate Matter Concentrations for U.S. Counties in the U.S./
Mexico Border Region
Ambient Concentrations of Manganese Compounds
in EPA Region 5
2.2.2
2.2.2
2-52
2-54
Page
2-56
2-58
N/R = National Indicator displayed at EPA Regional scale
2-8
EPA's 2008 Report on the Environment
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Carbon Monoxide Emissions
Carbon monoxide (CO) gas forms primarily when
carbon fuels are not burned completely. Mobile
sources account for the majority of CO emissions (U.S.
EPA, 2003). These sources include both on-road vehicles
(e.g., cars, trucks, motorcycles) and nonroad vehicles and
engines (e.g., farm equipment, construction equipment,
aircraft, marine vessels). Consequently, high concentra-
tions of CO generally occur in areas with heavy traffic
congestion. In cities, as much as 95 percent of all CO
emissions may come from automobile exhaust (U.S. EPA,
2003). Other sources of CO emissions include industrial
processes, non-transportation fuel combustion, and natural
sources, such as wildfires. Fuel-burning appliances also
are a large source of CO releases in indoor environments.
Undetected releases of carbon monoxide in indoor settings
can present serious health risks to building occupants. The
CO Concentrations indicator (p. 2-11) describes health
hazards associated with inhaling CO.
This indicator presents CO emissions from tradition-
ally inventoried anthropogenic source categories: (1) "Fuel
combustion," which includes emissions from coal-, gas-,
and oil-fired power plants and industrial, commercial, and
institutional sources, as well as residential heaters (e.g.,
•wood-burning stoves) and boilers; (2) "Other industrial
processes," which includes chemical production, petro-
leum refining, metals production, and industrial processes
other than fuel combustion; (3) "On-road vehicles,"
•which includes cars, trucks, buses, and motorcycles; and
(4) "Nonroad vehicles and engines," such as farm and
construction equipment, lawnmowers, chainsaws, boats,
ships, snowmobiles, aircraft, and others. The indicator
also includes estimates of biogenic CO emissions in 2002.
Biogenic emissions were estimated using the Biogenic
Emissions Inventory System Model, Version 3.12, with
data from the Biogenic Emissions Landcover Database and
2001 annual meteorological data.
CO emissions data are tracked by the National Emis-
sions Inventory (NEI). The NEI is a composite of data from
many different sources, including industry and numerous
state, tribal, and local agencies. Different data sources use
different data collection methods, and many of the emissions
data are based on estimates rather than actual measurements.
For most fuel combustion sources and industrial sources,
emissions are estimated using emission factors. Emissions
from on-road and nonroad sources were estimated using
EPA-approved modeling approaches (U.S. EPA, 2007a).
NEI data have been collected since 1990 and cover all
50 states and their counties, D.C., the U.S. territories of
Puerto Rico and Virgin Islands, and some of the territories
of federally recognized American Indian nations. Data are
presented for 1990 and from 1996 to 2002; prior to 1996,
only the 1990 data have been updated to be comparable to
the more recent inventories.
Exhibit 2-1. CO emissions in the U.S. by
source category, 1990 and 1996-2002
160
_140
^n
i 120
1100
1. 80
o>
| 60
'o>
•| 40
m 20
0
A. Anthropogenic CO emissions by source category3
Fuel combustion
Other industrial processes
On-road vehicles
Nonroad vehicles and engines
'90
'96 '97 '98 '99 '00 '01 '02
Year
aData are presented for 1990
and 1996-2002, as datasets
from these inventory years are
all fully up to date. Data are
available for inventory years
1991-1995, but these data have
not been updated to allow
comparison with data from
1990 and 1996-2002.
Data source: U.S. EPA, 2007b
B. Relative amounts of CO
emissions from anthropogenic
and biogenic sources, 2002
Biogenic
5%
What the Data Show
This indicator focuses on trends in CO emissions from
anthropogenic sources. However, CO emissions from bio-
genic sources were estimated for 2002 to provide a sense of
the relative contributions of natural versus anthropogenic
emissions (Exhibit 2-1, panel B). Nationally, biogenic
emissions were estimated to contribute approximately 5
percent to the CO emissions from all sources during 2002.
Nation-wide estimated anthropogenic CO emissions have
decreased 35 percent between 1990 and 2002, the most
recent year for which aggregate NEI emissions estimates
are available (Exhibit 2-1, panel A). Almost the entire
emissions reduction is attributed to decreased emissions
from on-road mobile sources. In 2002, mobile sources
(both on-road and nonroad sources combined) accounted
for 90 percent of the nation's total anthropogenic CO
emissions. The CO emissions reductions are reflected in
corresponding reductions in ambient concentrations (the
CO Concentrations indicator, p. 2-11).
Net estimated anthropogenic CO emissions declined
in all EPA Regions between 1990 and 2002 (Exhibit
2-2). The largest decrease (10.84 million tons) occurred
in Region 9, and the smallest decrease (1.33 million tons)
occurred in Region 10.
EPA's 2008 Report on the Environment
2-9
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INDICATOR
Carbon Monoxide Emissions (continued)
Indicator Limitations
• Comparable CO emissions estimates through the NEI are
available only for 1990 and 1996-2002. Data for 1991-1995
are not provided due to differences in emissions estimation
methodologies from other inventory years, which could
lead to improper trend assessments.
• CO emissions from "miscellaneous sources," including
\vildfires, are not included in the total emissions. Yearly
fluctuations in wildfire emissions have the potential to
mask trends in anthropogenic emissions and therefore have
been excluded from the trends graphics. Details on emis-
sions from miscellaneous sources can be found by down-
loading 2002 NEI inventory data for the "nonpoint sector"
(http: //www.epa. gov/ttn/chief/net/20 02inventory. html).
• The emissions data for CO are largely based on estimates
that employ emission factors generated from empirical
and engineering studies, rather than on actual measure-
ments of CO emissions. Although these estimates are
generated using -well-established approaches, the esti-
mates have uncertainties inherent in the emission factors
and emissions models used to represent sources for which
emissions have not been directly measured.
• The methodology for estimating emissions is continually
reviewed and is subject to revision. Trend data prior to
any revisions must be considered in the context of
those changes.
• Not all states and local agencies provide the same data or
level of detail for a given year.
Data Sources
Summary data in this indicator were provided by EPA's
Office of Air Quality Planning and Standards, based on
biogenic and anthropogenic CO emissions data in the
NEI (U.S. EPA, 2007b) (http://www.epa.gov/ttn/chief/
net/2002inventory.html). This indicator aggregates the
NEI data by source type (anthropogenic or biogenic),
source category, and EPA Region.
References
U.S. EPA (United States Environmental Protection
Agency). 2007a. Documentation for the final 2002 mobile
National Emissions Inventory, Version 3.
Exhibit 2-2. CO emissions in the U.S. by
EPA Region, 1990 and 1996-20023
30
-. 25
tf>
c
o
c 20
O
I 15
o>
c
110
E
m 5
0
-R1
-R2
-R3
-R4
-R5
R6
R7
R8
-R9
-R10
'96 '97 '98 '99 '00 '01 '02
Year
aData are presented for 1990
and 1996-2002, as datasets
from these inventory years are
all fully up to date. Data are
available for inventory years
1991-1995, but these data have
not been updated to allow
comparison with data from
1990 and 1996-2002.
Data source: U.S. EPA, 2007b
EPA Regions
U.S. EPA. 2007b. Data from the 2002 National Emissions
Inventory, Version 3.0. Accessed 2007.
U.S. EPA. 2003. National air quality and emissions trends
report—2003 special studies edition. EPA/454/R-03/005.
Research Triangle Park, NC.
2-10
EPA's 2008 Report on the Environment
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Ambient Concentrations of Carbon Monoxide
Carbon monoxide (CO) gas forms primarily when car-
bon fuels are not burned completely. Elevated ambient
air concentrations of CO are hazardous because inhaled
CO enters the bloodstream and reduces the amount of
oxygen that the blood can deliver to the body's organs and
tissues. If exposure concentrations are high enough, poten-
tially serious cardiovascular and neurological effects can
result. Visual impairment, reduced work capacity, reduced
manual dexterity, poor learning ability, and difficulty in
performing complex tasks are all associated with exposure
to elevated CO levels (U.S. EPA, 2000).
Motor vehicle exhaust currently accounts for the
majority of CO emissions nation-wide, and as much as 95
percent of CO emissions in cities with high traffic con-
gestion. Other anthropogenic sources of CO emissions
include fossil fuel combustion for heating and power
generation, metals processing, and chemical manufactur-
ing. The highest ambient air concentrations of CO often
occur during nighttime inversion conditions, which trap
pollutants near ground level. These conditions are most
frequently observed during the cold winter months (U.S.
EPA, 2003).
This indicator presents ambient CO concentrations
in parts per million (ppm) from 1980 to 2006, based on
continuous measurements averaged over 8-hour time
frames. The 8-hour standard is indicative of exposures
occurring over a sustained period of time, for example,
an outdoor -worker's exposure over the course of a -work
day. This indicator displays trends in the annual second
highest 8-hour CO concentrations for 144 sites in 102
counties nation-wide that have consistent data for the
period of record in the State and Local Air Monitoring
Stations net-work or by other special purpose monitors.
It also shows trends in the average 8-hour measurements
in each EPA Region. This indicator's exhibits display the
National Ambient Air Quality Standard (NAAQS) for
CO as a point of reference, but the fact that the national or
any regional second highest 8-hour values fall below the
standard does not mean that all monitoring sites nation-
ally or in the EPA Region also are below the standard.
The indicator displays trends in the number of the 144 sites
nation-wide at -which reported CO concentrations -were
above the level of the 8-hour standard, but this statistic is
not displayed for each EPA Region.
What the Data Show
The 2006 annual second highest 8-hour CO concentra-
tion averaged across 144 monitoring sites nation-wide -was
75 percent lower than that for 1980, and is the lowest level
recorded during the past 27 years (Exhibit 2-3, panel A).
The downward trend in CO concentrations in the 1990s
parallels the downward trend observed in CO emissions,
•which has been attributed largely to decreased emissions
from mobile sources (the CO Emissions indicator, p. 2-9).
Exhibit 2-3. Ambient CO concentrations in the
U.S., 1980-20063
A. Ambient concentrations
^§
= o
90% of sites have concentrations below this line
NAAQS = 9 ppm
10% of sites have
concentrations below this line
'82 '84 '8
'90 '92 '94 '96
Year
'00 '02 '04 '06
CO
CD
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1 °
O CD
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B. Number of trend sites above NAAQS
'82 '8
'90 '92 '94 '96
Year
'00 '02 '04 '06
Coverage: 144 monitoring sites in 102 counties nationwide (out of
a total of 375 sites measuring CO in 2006) that have sufficient
data to assess CO trends since 1980.
Data source: U.S. EPA, 2007
In addition, of the 144 sites used to determine this trend
(out of 375 total monitoring sites that -were operating in
2006), the number reporting CO concentrations above the
level of the CO standard declined to zero over the same
period (Exhibit 2-3, panel B).
Also shown in Exhibit 2-3 (panel A) are the 90th and 10th
percentiles based on the distribution of annual statistics at
the monitoring sites. This provides additional graphical
representation of the distribution of measured concentra-
tions across the monitoring sites for a given year. Thus, the
graphic displays the concentration range -where 80 percent
of measured values occurred for that year.
Consistent -with the nation-wide trend, CO levels in all
ten EPA Regions have steadily decreased since 1980, -with
percent reductions over this period ranging from 68 per-
cent (Region 7) to 85 percent (Region 1) (Exhibit 2-4).
EPA's 2008 Report on the Environment
2-11
-------
INDICATOI
Ambient Concentrations of Carbon Monoxide (continued)
Exhibit 2-4. Ambient CO concentrations in the
contiguous U.S. by EPA Region, 1980-20063
NAAQS = 9 ppm
'90 '92 '94 '96 '98 '00 '02 '04 '06
Year
Coverage: 141 monitoring sites
in the EPA Regions (out of a total
of 375 sites measuring CO in
2006) that have sufficient data to
assess CO trends since 1980.
Data source: U.S. EPA, 2007
EPA Regions
Indicator Limitations
• Because most CO monitoring sites are located in high-
traffic urban areas, the nation-wide trends presented in
this indicator might not accurately reflect conditions
outside the immediate urban monitoring areas.
• Because of the relatively small number of trend sites in
some EPA Regions, the regional trends are subject to
greater uncertainty than the national trends. Some EPA
Regions with low average concentrations may include
areas with high local concentrations, and vice versa.
• To ensure that long-term trends are based on a consistent
set of monitoring sites, selection criteria were applied to
identify the subset of CO monitoring sites with sufficient
data to assess trends since 1980. Monitoring sites -with-
out sufficient data are not included in the trend analysis.
Some excluded monitoring sites reported CO concentra-
tions above the level of the CO standard over the time
frame covered by this indicator. In 2006, for example,
one monitoring site in the U.S. recorded CO concentra-
tions above the level of the NAAQS, but did not have
sufficient long-term data to be considered a trend site for
this indicator.
Data Sources
Summary data in this indicator -were provided by EPA's
Office of Air Quality Planning and Standards, based on
CO ambient air monitoring data in EPA's Air Quality
System (U.S. EPA, 2007) (http://www.epa.gov/ttn/airs/
airsaqs/). National and regional trends in this indicator are
based on the subset of CO monitoring stations that have
sufficient data to assess trends since 1980.
References
U.S. EPA (United States Environmental Protection
Agency). 2007. Data from the Air Quality System.
Accessed 2007.
U.S. EPA. 2003. National air quality and emissions trends
report—2003 special studies edition. EPA/454/R-03/005.
Research Triangle Park, NC.
U.S. EPA. 2000. Air quality criteria for carbon monoxide,
2000. EPA/600/P-99/001F. Research Triangle Park, NC.
INDICATOI
Lead Emissions
Lead is a naturally occurring metal found in small amounts
in rock and soil. Lead has been used industrially in the
production of gasoline, ceramic products, paints, metal
alloys, batteries, and solder. In the past, automotive sources
•were the major contributors of lead emissions to the atmo-
sphere. After leaded motor vehicle fuels were phased out
during the 1970s and 1980s, the contribution of air emis-
sions of lead from the transportation sector, and particularly
the automotive sector, greatly declined. Today, industrial
processes, primarily metals processing, account for a large
portion of lead emissions to the atmosphere and the highest
levels of airborne lead are usually found near industrial oper-
ations that process materials containing lead, such as smelters
(U.S. EPA, 2003). Exposure to lead occurs mainly through
inhalation of air and ingestion of lead in food, water, soil, or
dust. The Lead Concentrations indicator (p. 2-14) describes
health hazards associated with lead exposures.
This indicator presents lead emissions from tradition-
ally inventoried anthropogenic source categories: (1) "Fuel
combustion," which includes emissions from coal-, gas-,
and oil-fired power plants and industrial, commercial,
and institutional sources, as well as residential heaters and
2-12
EPA's 2008 Report on the Environment
-------
Lead Emissions
(continued)
boilers; (2) "Other sources," which includes chemical
production and petroleum refining; (3) "On-road vehi-
cles," which includes cars, trucks, buses, and motorcycles;
(4) "Nonroad vehicles and engines," such as farm and
construction equipment, lawnmowers, chainsaws, boats,
ships, snowmobiles, aircraft, and others; and (5) "Metals
industrial processing." Since metals processing is one of
the largest sources of lead emissions, the indicator includes
a metals source category in addition to the four categories
presented in the other emissions indicators.
For the years 1970 through 1985, the primary source
for lead emissions data was the National Emissions Data
System (NEDS) archives. Since 1990, lead emissions data
have been tracked by the National Emissions Inventory
(NEI). The NEI is a composite of data from many differ-
ent sources, including industry and numerous state, tribal,
and local agencies. Different data sources use different
data collection methods, and many of the emissions data
are based on estimates rather than actual measurements.
For most industrial processes and fuel combustion sources,
emissions are estimated using emission factors. Emissions
from on-road and nonroad sources were estimated using
EPA-approved modeling approaches (U.S. EPA, 2007a).
Data for lead emissions cover all 50 states and their coun-
ties, D.C., the U.S. territories of Puerto Rico and Virgin
Islands, and some of the territories of federally recognized
American Indian nations.
What the Data Show
Between 1970 and 2002, estimated nation-wide lead emis-
sions decreased by 99 percent (219,210 tons), mostly due
to reductions from on-road vehicle sources after lead was
removed from gasoline (Exhibit 2-5). Since 1990, further
declines in lead emissions occurred, mostly due to reduc-
tions from on-road vehicles and nonroad vehicles and
engines. Sharp declines in nation-wide air concentrations
of lead between 1980 and 1990 paralleled the emissions
reductions (the Lead Concentrations indicator, p. 2-14).
Indicator Limitations
• Although lead emissions trends have been generated using
•well-established estimation methods, the data reflect
estimates based on empirical and engineering models and
not actual measurement of lead emissions. These esti-
mates have uncertainties inherent in the emission factors
and emissions models used to represent sources for which
emissions have not been directly measured.
• The method for estimating lead emissions for fuel com-
bustion and industrial sources changed in 1999 to reduce
uncertainties inherent in the previous method (U.S.
EPA, 2003). Despite the change in methodology, the
long-term trend is still reliable.
Exhibit 2-5. Lead emissions in the U.S. by
source category, 1970-1999 and 2002a
n Other sources
D Nonroad vehicles and engines
n Fuel combustion
D Metals industrial processing
D On-road vehicles
70 75
'85 '90-'99 and'02u
Year
Emissions inventory
data are presented
for years that allow
reliable estimation of
long-term trends.
bData for 1990-1999
and 2002 are average
annual emissions
(thousand tons per
year) and are therefore
comparable to the
annual emissions
shown for the earlier years.
Data source: U.S. EPA, 2001, 2007b
— o
Detail
'90 '92 '94
'96
Year
• Not all states and local agencies provide the same data or
level of detail for a given year.
Data Sources
Summary data in this indicator were provided by EPA's
Office of Air Quality Planning and Standards, based on
lead emissions data from two sources. Emissions data
from 1970 to 1985 are from EPA's NEDS archives, and
data summaries for this time frame can be found in
various EPA publications (e.g., U.S. EPA, 2001). Emis-
sions data for 1990-1999 and 2002 are available from the
NEI (U.S. EPA, 2007b) (http://www.epa.gov/ttn/chief/
net/2002inventory.html). This indicator aggregates the
emissions data by source category.
References
U.S. EPA (United States Environmental Protection
Agency). 2007a. Documentation for the final 2002 mobile
National Emissions Inventory, Version 3.
EPA's 2008 Report on the Environment
2-13
-------
INDICATOR
Lead Emissions (continued)
U.S. EPA. 2007b. Data from the 2002 National Emissions
Inventory, Version 3.0. Accessed 2007.
U.S. EPA. 2003. National air quality and emissions trends
report—2003 special studies edition. EPA/454/R-03/005.
Research Triangle Park, NC.
U.S. EPA. 2001. National air quality and emissions trends
report, 1999. EPA/454/R-01/004. Research Triangle Park,
NC.
INDICATOR
Ambient Concentrations of Lead
Lead is a naturally occurring metal found in small amounts
in rock and soil. Despite steep decreases in emissions
since 1970 (the Lead Emissions indicator, p. 2-12), lead
remains an important environmental health issue because
exposure to high levels has been associated with serious
health effects, including neurological impairments such as
seizures, mental retardation, and behavioral disorders (CDC,
2005). Even at low doses, lead exposure can have adverse
effects on the nervous systems of fetuses and young children
(the Blood Lead indicator, p. 5-10) (U.S. EPA, 2006). People
can be exposed to lead by inhaling airborne particles that
contain lead, drinking contaminated water, eating contami-
nated food items, or ingesting non-food items that contain
lead, such as dust and paint chips.
Lead has been used industrially in the production of
gasoline, ceramic products, paints, metal alloys, batteries,
and solder. Some chemicals containing lead were previ-
ously added to gasoline to enhance vehicle performance,
but that practice was phased out during the 1970s and
1980s. As a result, air emissions of lead from the transpor-
tation sector decreased dramatically during that period
(the Lead Emissions indicator, p. 2-12). Today, the high-
est levels of airborne lead are usually found near industrial
operations that process materials containing lead, such as
smelters (U.S. EPA, 2003).
This indicator presents ambient lead concentrations in
micrograms per cubic meter (jag/m3) from 1980 to 2006.
Trends for this indicator are based on measurements made
at 15 monitoring stations in 10 counties nation-wide. These
trend sites were selected because they are part of the State
and Local Air Monitoring Stations net-work or are special
purpose monitors and they have consistently measured
ambient air concentrations of lead over the entire period of
interest. Reported values are annual maximum quarterly
averages. This indicator's exhibit displays the lead National
Ambient Air Quality Standard (NAAQS) as a point
of reference, but the fact that the average national lead
concentrations fall below the standard does not mean that
all monitoring sites also are below the standard.
What the Data Show
Between 1980 and 2006, average lead concentrations
decreased 96 percent nationally (Exhibit 2-6, panel A).
This decrease, -which occurred mostly during the 1980s
and early 1990s, is largely attributed to reduced lead
content in gasoline (U.S. EPA, 2003). In addition, of
the 15 sites used to determine this trend (out of 161 total
monitoring sites that -were operating in 2006), the num-
ber reporting lead concentrations above the level of the
NAAQS declined to zero over the same period (Exhibit
2-6, panel B).
Also shown in Exhibit 2-6 (panel A) are the 90th and 10th
percentiles based on the distribution of annual statistics at
the monitoring sites. This provides additional graphical
representation of the distribution of measured concentra-
tions across the monitoring sites for a given year. Thus, the
exhibit displays the concentration range -where 80 percent
of measured values occurred for each year.
Indicator Limitations
• Because most lead monitoring sites are located in urban
areas, the nation-wide trends might not accurately reflect
conditions outside the immediate urban monitoring areas.
• To ensure that long-term trends are based on a consistent
set of monitoring sites, selection criteria -were applied to
identify the subset of lead monitoring sites -with sufficient
data to assess trends since 1980. Monitoring sites -without
sufficient data are not included in the trend analysis. Some
excluded monitoring sites reported lead concentrations
above the level of the lead standard over the time frame
covered by this indicator. In 2006, for example, two
monitoring sites recorded lead concentrations above the
level of the NAAQS, but did not have sufficient long-term
data to be considered trend sites for this indicator.
2-14
EPA's 2008 Report on the Environment
-------
INDICATOI
Ambient Concentrations of Lead (continued)
Data Sources
Summary data in this indicator were provided by EPA's
Office of Air Quality Planning and Standards, based on
lead ambient air monitoring data in EPA's Air Quality
System (U.S. EPA, 2007) (http://www.epa.gov/ttn/airs/
airsaqs/). National trends in this indicator are based on the
subset of lead monitoring stations that have sufficient data
to assess trends since 1980.
References
CDC (Centers for Disease Control and Prevention,
National Center for Environmental Health). 2005. Third
national report on human exposure to environmental
chemicals. NCEH Pub. No. 05-0570.
U.S. EPA (United States Environmental Protection
Agency). 2007. Data from the Air Quality System.
Accessed 2007.
U.S. EPA. 2006. Air quality criteria for lead. EPA/600/
R-5/144aF. Research Triangle Park, NC.
U.S. EPA. 2003. National air quality and emissions trends
report—2003 special studies edition. EPA/454/R-03/005.
Research Triangle Park, NC.
Exhibit 2-6. Ambient lead concentrations in
the U.S., 1980-20063
A. Ambient concentrations
a, 2.5r
01
2
« ZT 2.oL
ft \
t! ^_
1| 1.0
E 1
g 0.5
0 0
'8
l\IAAQS=1.5ug/m3
90% of sites have concentrations below this line
\i
Avey^\ 10% of sites have
Median ^^-concentrations below this line
) '82 '84 '86 '88 '90 '92 '94 '96 '98 '00 '02 '04 '06
Year
B. Number of trend sites above NAAQS
13 ^ 5
fll 4
§ gl
£i 2 T-^
•S §5 co
^ o a
ill
•« a> 2
01 0>
^3 CC -^
2^ > "o
^-^ ns
"o >- g 1
S|-S2
"E §
'80 '82 '84 '86 '88 '90 '92 '94 '96 '98 '00 '02 '04 '06
Year
Coverage: 15 monitoring in 10 counties nationwide (out of a total of
161 sites measuring lead in 2006) that have sufficient data to assess
lead trends since 1980.
Data source: U.S. EPA, 2007
EPA's 2008 Report on the Environment
2-15
-------
INDICATOR
Nitrogen Oxides Emissions
"N
oxides" (NOJ is the term used to describe the
sum of nitric oxide (NO), nitrogen dioxide (NO2), and
other oxides of nitrogen. Most airborne NO comes from
combustion-related emissions sources of human origin,
primarily fossil fuel combustion in electric utilities, high-
temperature operations at other industrial sources, and
operation of motor vehicles. However, natural sources, like
biological decay processes and lightning, also contribute to
airborne NO . Fuel-burning appliances, like home heat-
ers and gas stoves, produce substantial amounts of NO in
indoor settings (U.S. EPA, 2003).
NO plays a major role in several important environmen-
tal and human health issues. Short-term and long-term
exposures to elevated air concentrations of NO2 are associ-
ated with various acute and chronic respiratory effects (U.S.
EPA, 1993). NO and volatile organic compounds react in
the presence of sunlight to form ozone, which also is associ-
ated with human health and ecological effects (the Ozone
Concentrations indicator, p. 2-22). NO and other pollut-
ants react in the air to form compounds that contribute to
acid deposition, which can damage forests and cause lakes
and streams to acidify (the Acid Deposition indicator, p.
2-37). Deposition of NO also affects nitrogen cycles and
can contribute to nuisance growth of algae that can disrupt
the chemical balance of nutrients in water bodies, especially
in coastal estuaries (the Lake and Stream Acidity indicator,
p. 2-42; the Trophic State of Coastal Waters indicator,
p. 3-38). NO also plays a role in several other environmen-
tal issues, including formation of particulate matter
(the PM Concentrations indicator, p. 2-29), decreased vis-
ibility (the Regional Haze indicator, p. 2-33), and global
climate change (the U.S. Greenhouse Gas Emissions indica-
tor, p. 2-64; the Greenhouse Gas Concentrations indicator,
p. 2-66).
This indicator presents NO emissions from tradition-
ally inventoried anthropogenic source categories: (1) "Fuel
combustion: selected power generators," which includes
emissions from coal-, gas-, and oil-fired power plants that are
required to use continuous emissions monitors (CEMs) to
report emissions as part of the Acid Rain Program (ARP); (2)
"Fuel combustion: other sources," which includes industrial,
commercial, and institutional sources, as well as residential
heaters and boilers not required to use CEMs; (3) "Other
industrial processes," which includes chemical production and
petroleum refining; (4) "On-road vehicles," which includes
cars, trucks, buses, and motorcycles; (5) "Nonroad vehicles
and engines," such as farm and construction equipment,
lawnmowers, chainsaws, boats, ships, snowmobiles, aircraft,
and others. Since a substantial portion of airborne NO comes
from fossil fuel combustion in electric utilities, this indicator
includes the separate category for "selected power genera-
tors" in addition to the four categories presented in the other
emissions indicators. The indicator also includes estimates of
Exhibit 2-7. NOX emissions in the U.S. by
source category, 1990 and 1996-2002
A. Anthropogenic NOX emissions by source category3
ns (million tons)
Emissio
30
25
20
15
10
5
n
Other industrial processes
_A
Fuel combustiorT~~ >r~— -\
selected power generators NT
Fuel combustion: other sources
\
On-road vehicles
Nonroad vehicles and engines
'90
'96 '97
99
'00
'01
'02
Year
B. Relative amounts of NOX
emissions from anthropogenic
and biogenic sources, 2002
aData are presented for 1990
and 1996-2002, as datasets
from these inventory years are
fully up to date. Data are
available for inventory years
1991-1995, but these data have
not been updated to allow
comparison with data from
1990 and 1996-2002.
h 95%
This category includes
emissions from only those
power plants required to use continuous emissions monitors under the
Acid Rain Program.
Data source: U.S. EPA, 2007b
biogenic NO emissions in 2002. Biogenic emissions were
estimated using the Biogenic Emissions Inventory System
Model, Version 3.12, with data from the Biogenic Landcover
Database and 2001 annual meteorological data.
NO emissions data are tracked by the National Emis-
sions Inventory (NEI). The NEI is a composite of data
from many different sources, including industry and
numerous state, tribal, and local agencies. Different data
sources use different data collection methods, and many of
the emissions data are based on estimates rather than actual
measurements. For major electricity generating units, most
data come from CEMs that measure actual emissions. For
other fuel combustion sources and industrial processes,
data are estimated using emission factors. Emissions from
on-road and nonroad sources were estimated using EPA-
approved modeling approaches (U.S. EPA, 2007a).
NEI data have been collected since 1990 and cover all
50 states and their counties, D.C., the U.S. territories of
Puerto Rico and Virgin Islands, and some of the territories
of federally recognized American Indian nations. Data are
presented only for 1990 and the years from 1996 to 2002;
2-16
EPA's 2008 Report on the Environment
-------
INDICATOI
Nitrogen Oxides Emissions (continued)
prior to 1996, only the 1990 data have been updated to be
comparable to the more recent inventories.
What the Data Show
This indicator focuses on trends in NO emissions from
X
anthropogenic sources. However, NO emissions from
biogenic sources were estimated for 2002 to provide a sense
of the relative contributions of natural versus anthropogenic
emissions. Nationally, biogenic emissions were estimated to
contribute approximately 5 percent to NO emissions from
all sources during 2002 (Exhibit 2-7, panel B).
According to the NEI data, estimated nation-wide
anthropogenic emissions of NO decreased by 17 percent
between 1990 and 2002 (from 25,160,000 to 20,917,000
tons) (Exhibit 2-7, panel A). This downward trend results
primarily from emissions reductions at electric utilities and
among on-road mobile sources. Although total nation-
wide anthropogenic NO emissions decreased during this
period, emissions from some sources (such as nonroad
vehicles and engines) have increased since 1990.
Estimated anthropogenic NO emissions in nine of
the ten EPA Regions decreased between 1990 and 2002
(Exhibit 2-8). The percent change in emissions over this
time frame ranged from a 36 percent decrease (in Region
2) to a 6 percent increase (in Region 10), and the largest
absolute reduction (919,000 tons) occurred in Region 3.
Indicator Limitations
• Comparable NO emissions estimates through the NEI
are available only for 1990 and 1996-2002. Data for
1991-1995 are not provided due to differences in emis-
sions estimation methodologies from other inventory
years, which could lead to improper trend assessments.
• NO emissions from miscellaneous sources are not
X
included in the total emissions.
• Though NOx emissions from most electric utilities are
measured directly using continuous monitoring devices,
NOx emissions data for most other source types are
estimates. These estimates are generated using -well-
established approaches, but still have uncertainties inher-
ent in the emission factors and emissions models used
to represent sources for -which emissions have not been
directly measured.
• The methodology for estimating emissions is continually
reviewed and is subject to revision. Trend data prior to
any revisions must be considered in the context of
those changes.
• Not all states and local agencies provide the same data or
level of detail for a given year.
Data Sources
Summary data in this indicator -were provided by EPA's
Office of Air Quality Planning and Standards, based on
Exhibit 2-8. NOX emissions in the U.S. by EPA
Region, 1990 and 1996-20023
•& 2
E
LLJ
1
0
-R1
-R2
-R3
-R4
-R5
R6
R7
R8
-R9
—R10
'96 '97 '98 '99 '00 '01 '02
Year
aData are presented for 1990
and 1996-2002, as datasets
from these inventory years are
fully up to date. Data are
available for inventory years
1991-1995, but these data have
not been updated to allow
comparison with data from
1990 and 1996-2002.
Data source: U.S. EPA, 2007b
EPA Regions
anthropogenic and biogenic NOx emissions data in EPA's
NEI (U.S. EPA, 2007b) (http://www.epa.gov/ttn/chief/
net/2002inventory.html). This indicator aggregates the NEI
data by source type (anthropogenic or biogenic), source
category, and EPA Region.
References
U.S. EPA (United States Environmental Protection
Agency). 2007a. Documentation for the final 2002 mobile
National Emissions Inventory, Version 3.
U.S. EPA. 2007b. Data from the 2002 National Emissions
Inventory, Version 3.0. Accessed 2007.
U.S. EPA. 2003. National air quality and emissions trends
report—2003 special studies edition. EPA/454/R-03/005.
Research Triangle Park, NC.
U.S. EPA. 1993. Air quality criteria for oxides of nitrogen.
EPA/600/8-91/049aF-cF. Research Triangle Park, NC.
EPA's 2008 Report on the Environment
2-17
-------
INDICATOR
Ambient Concentrations of Nitrogen Dioxide
Nitrogen dioxide (NO2) is a reddish-brown, highly reac-
tive gas that is formed in the ambient air through the
oxidation of nitric oxide (NO). Nitrogen dioxide is one
in a group of highly reactive gases generically referred to
as "nitrogen oxides" (NO ), all of which contain nitrogen
and oxygen in varying amounts. NO plays a major role in
the formation of ozone in the atmosphere through a com-
plex series of reactions with volatile organic compounds.
NO2 is the most -widespread and commonly found nitro-
gen oxide (U.S. EPA, 2003).
Short-term exposures (e.g., less than 3 hours) to low
levels of NO2 may lead to changes in airway responsiveness
and lung function in individuals with preexisting respira-
tory illnesses. These exposures may also increase respira-
tory illnesses in children. Long-term exposures to NO
may lead to increased susceptibility to respiratory infection
and may cause irreversible alterations in lung structure
(U.S. EPA, 1995).
Atmospheric transformation of NO can lead to the
formation of ozone and nitrogen-bearing particles (e.g.,
nitrates, nitric acid). Deposition of nitrogen can lead to fer-
tilization, eutrophication, or acidification of terrestrial, -wet-
land, and aquatic (e.g., fresh water bodies, estuaries, coastal
•water) systems. These effects can alter competition among
existing species, leading to changes in species abundance and
distribution within communities. For example, eutrophic
conditions in aquatic systems can produce explosive growth
of algae leading to hypoxia or an increase in levels of toxins
harmful to fish and other aquatic life (U.S. EPA, 1993).
This indicator presents ambient NO2 concentrations in
parts per million (ppm) from 1980 to 2006, based on the
annual arithmetic average. The indicator displays trends
averaged over 87 sites in 64 counties nation-wide that have
consistent data for the period of record in the State and
Local Air Monitoring Stations net-work or by special pur-
pose monitors. It also shows trends in the annual average
NO measurements in each EPA Region. This indicator's
exhibits display the NO2 National Ambient Air Quality
Standard (NAAQS) as a point of reference, but the fact that
the national or any regional average values fall below the
standard does not mean that all monitoring sites nation-
ally or in the EPA Region also are below the standard.
This indicator displays trends in the number of the 87 sites
nation-wide at which NO concentrations exceeded the level
of the annual average standard over the period of record, but
this statistic is not displayed for each EPA Region.
What the Data Show
The national annual average NO2 concentration in 2006
•was 41 percent lower than that recorded in 1980 (Exhibit
2-9, panel A). Also shown on this graph are the 90th and
10th percentiles of NO2 concentrations based on the distri-
bution of annual statistics at the monitoring sites. This pro-
vides additional graphical representation of the distribution
Exhibit 2-9. Ambient NC>2 concentrations in the
U.S., 1980-20063
A. Ambient concentrations
NAAQS = 0.053 ppm
90% of sites have concentrations below this line
10% of sites have
concentrations below this line
'90 '92 '94
Year
'02 '04 '06
B. Number of trend sites above NAAQS
CO O
CD _Q
II
P 13
£
E
'82 '84
III
88 '90 '92 '94 '96 '98 '00 '02 '04 '06
Year
Coverage: 87 monitoring sites in 64 counties nationwide (out of a
total of 369 sites measuring N02 in 2006) that have sufficient data
to assess I\I02 trends since 1980.
Data source: U.S. EPA, 2007
of measured concentrations across the monitoring sites for
a given year. Thus, for each year, the graphic displays the
concentration range -where 80 percent of measured values
occurred. The highest annual average NO2 concentra-
tions are typically found in urban areas. In addition, of
the 87 sites used to determine this trend (out of 369 total
monitoring sites that -were operating in 2006), the number
reporting NO2 concentrations above the level of the NO2
standard declined from seven sites in 1981 to zero sites
since 1992 (Exhibit 2-9, panel B).
NO2 levels in all ten EPA Regions have steadily
decreased since 1980, -with percent reductions over this
time ranging from 20 percent in Region 8 to 49 percent in
Region 1 (Exhibit 2-10).
2-18
EPA's 2008 Report on the Environment
-------
INDICATOI
Ambient Concentrations of Nitrogen Dioxide (continued)
The decrease in NO2 concentrations in this indicator is
consistent with the decreasing NO emissions observed
over the past decade (the Nitrogen Oxides Emissions indi-
cator, p. 2-16).
Indicator Limitations
• Because ambient monitoring for NO occurs almost
exclusively in high-traffic urban areas, the average
concentrations presented in this indicator likely may not
reflect NO2 levels in rural areas. Also, in rural areas, air
mass aging could foster greater relative levels of peroxy-
acetyl nitrate (PAN) and nitric acid which can cause a
positive interference in NO2 measurements.
• The measurement of NO is based on the conversion of
NO2 to NO and the subsequent detection of NO using
the chemiluminescence technique. Because there are
other nitrogen-containing compounds, such as PAN and
nitric acid, that can be converted to NO, the chemilu-
minescence technique may overestimate NO2 concentra-
tions due to these interferences. Measurement devices
•with ultraviolet photolytic converters are less prone to
interferences than devices with heated surfaces (or cata-
lysts) upstream of the chemiluminescence detector.
• Because of the relatively small number of trend sites in
some EPA Regions, the regional trends are subject to
greater uncertainty than the national trends. Some EPA
Regions with low average concentrations may include
areas with high local concentrations, and vice versa.
• To ensure that long-term trends are based on a con-
sistent set of monitoring sites, selection criteria were
applied to identify the subset of NO2 monitoring sites
•with sufficient data to assess trends since 1980. Monitor-
ing sites \vithout sufficient data are not included in the
trend analysis. Some excluded monitoring sites reported
NO2 concentrations above the level of the NO2 standard
over the time frame covered by this indicator. In 2006,
however, no monitoring sites in the U.S. measured NO2
concentrations above the level of the NAAQS.
Data Sources
Summary data in this indicator were provided by EPA's
Office of Air Quality Planning and Standards, based on
NO ambient air monitoring data in EPA's Air Quality
System (U.S. EPA, 2007) (http://www.epa.gov/ttn/airs/
airsaqs/). National and regional trends in this indicator are
based on the subset of NO2 monitoring stations that have
sufficient data to assess trends since 1980.
Exhibit 2-10. Ambient NC>2 concentrations in the
contiguous U.S. by EPA Region, 1980-2006ab
0.06
E
Q.
0.05
0.04
0.03
0.02
0.01
0.00,
NAAQS = 0.053 ppm
R1
R2
R3
R4
-R5
R6
R7
R8
-R9
R10b
-Nat'l
'90 '92 '94
Year
'02 '04 '06
EPA Regions
Coverage: 87 monitoring sites
in the EPA Regions (out of a
total of 369 sites measuring
I\I02 in 2006) that have
sufficient data to assess N02
trends since 1980.
Because I\I02 in Region 10 has
been at such low
concentrations, none of this
Region's monitoring sites have a complete record dating back to 1980.
Thus, no trend line for Region 10 is shown.
Data source: U.S. EPA, 2007
References
U.S. EPA (United States Environmental Protection
Agency). 2007. Data from the Air Quality System.
Accessed 2007.
U.S. EPA. 2003. National air quality and emissions trends
report—2003 special studies edition. EPA/454/R-03/005.
Research Triangle Park, NC.
U.S. EPA. 1995. Review of the national ambient air qual-
ity standards for nitrogen oxides: Assessment of scientific
and technical information. EPA/452/R-95/005. Research
Triangle Park, NC.
U.S. EPA. 1993. Air quality criteria for oxides of nitrogen.
EPA/600/8-91/049aF-cF. Research Triangle Park, NC.
EPA's 2008 Report on the Environment
2-19
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INDICATOR
Volatile Organic Compounds Emissions
Volatile organic compounds (VOCs) are a large group of
organic chemicals that include any compound of carbon
(excluding carbon monoxide, carbon dioxide, carbonic acid,
metallic carbides or carbonates, and ammonium carbonate)
and that participate in atmospheric photochemical reac-
tions. VOCs are of interest in part because they contribute
to ozone formation (U.S. EPA, 2003a). Ozone (the Ozone
Concentrations indicator, p. 2-22) is formed from chemi-
cal reactions involving airborne VOCs, airborne nitrogen
oxides, and sunlight. VOCs are also of interest because
many individual VOCs are known to be harmful to human
health (the Benzene Concentrations indicator, p. 2-51; the
Air Toxics Emissions indicator, p. 2-48). Health effects vary
by pollutant. VOCs are emitted from a variety of sources,
including motor vehicles, chemical manufacturing facilities,
refineries, factories, consumer and commercial products, and
natural (biogenic) sources (mainly trees) (U.S. EPA, 2003b).
This indicator presents VOC emissions from tradition-
ally inventoried anthropogenic source categories:
(1) "Fuel combustion," which includes emissions from
coal-, gas-, and oil-fired power plants and industrial, com-
mercial, and institutional sources, as well as residential
heaters and boilers; (2) "Other industrial processes," which
includes chemical production, petroleum refining, metals
production, and processes other than fuel combustion; (3)
"On-road vehicles," which includes cars, trucks, buses, and
motorcycles; and (4) "Nonroad vehicles and engines," such
as farm and construction equipment, lawnmowers, chain-
saws, boats, ships, snowmobiles, aircraft, and others. The
indicator also includes estimates of biogenic VOC emis-
sions in 2002. Biogenic emissions were estimated using the
Biogenic Emissions Inventory System Model, Version 3.12,
•with data from the Biogenic Emissions Landcover Data-
base and 2001 annual meteorological data.
VOC emissions data are tracked by the National Emis-
sions Inventory (NEI). The NEI is a composite of data
from many different sources, including industry and
numerous state, tribal, and local agencies. Different data
sources use different data collection methods, and many of
the emissions data are based on estimates rather than actual
measurements. For most fuel combustion sources and
industrial sources, emissions are estimated using emission
factors. Emissions from on-road and nonroad sources were
estimated using EPA-approved modeling approaches (U.S.
EPA, 2007a).
NEI data have been collected since 1990 and cover all
50 states and their counties, D.C., the U.S. territories of
Puerto Rico and Virgin Islands, and some of the territories
of federally recognized American Indian nations. Data are
presented only for 1990 and the years from 1996 to 2002;
prior to 1996, only the 1990 data have been updated to be
comparable to the more recent inventories.
Exhibit 2-11. VOC emissions in the U.S. by
source category, 1990 and 1996-2002
25
f 20
_o
1 15
£ 10
o
'o>
(A
'E 5
A. Anthropogenic VOC emissions by source category3
—h
Fuel combustion
——— _\
. "\
Other industrial processes
On-road vehicles
Nonroad vehicles and engines
'90
'96
'97
'99
'01
'02
Year
aData are presented for 1990
and 1996-2002, as datasets
from these inventory years are
fully up to date. Data are
available for inventory years
1991-1995, but these data have
not been updated to allow
comparison with data from
1990 and 1996-2002.
Data source: U.S. EPA, 2007b
B. Relative amounts of VOC
emissions from anthropogenic
and biogenic sources, 2002
Anthropogenic
28%
What the Data Show
This indicator focuses on trends in VOC emissions from
anthropogenic sources. However, VOC emissions from
biogenic sources were estimated for 2002 to provide a sense
of the relative contributions of natural versus anthropogenic
emissions. Nationally, biogenic emissions were estimated
to contribute approximately 72 percent to VOC emissions
from all sources during 2002 (Exhibit 2-11, panel B). Thus,
VOC emissions from biogenic sources are larger than the
VOC emissions from all anthropogenic sources combined.
According to NEI data, national total estimated VOC
emissions from anthropogenic sources, excluding -wild-
fires and prescribed burns, decreased by 25 percent
between 1990 and 2002 (from 23,048,000 to 17,194,000
tons) (Exhibit 2-11, panel A). The over-whelming major-
ity of anthropogenic emissions reductions -were observed
among industrial processes and on-road mobile sources.
Combined, these two source categories accounted for 84
percent of the total nation-wide estimated anthropogenic
VOC emissions in 1990 (excluding -wildfires and pre-
scribed burns), but accounted for only 72 percent of the
nation-wide anthropogenic emissions in 2002.
2-20
EPA's 2008 Report on the Environment
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INDICATOI
Volatile Organic Compounds Emissions (continued)
Trends in estimated anthropogenic VOC emissions in
nine of the ten EPA Regions were consistent with the over-
all decline seen nationally from 1990 to 2002 (Exhibit 2-12).
Changes in VOC emissions ranged from a 52 percent reduc-
tion (Region 9) to a 16 percent increase (Region 10).
Indicator Limitations
• Comparable VOC emissions estimates through the NEI
are available only for 1990 and 1996-2002. Data for
1991-1995 are not provided due to differences in emis-
sions estimation methodologies from other inventory
years, which could lead to improper trend assessments.
• VOC emissions from "miscellaneous sources" are not
included in the total emissions. Details on emissions from
miscellaneous sources can be found by downloading 2002
NEI inventory data for the "nonpoint sector" (http://
www. epa.gov/ttn/chief/net/2002inventory.html).
• VOC emissions data are largely based on estimates that
employ emission factors generated from empirical and
engineering studies, rather than on actual measurements
of VOC emissions. These estimates are generated using
•well-established approaches, and quality assurance mea-
sures are implemented to ensure that the emissions data
entered in NEI meet data quality standards (U.S. EPA,
2006). Nonetheless, the estimates have uncertainties
inherent in the emission factors and emissions models
used to represent sources for which emissions have not
been directly measured.
• The methodology for estimating emissions is continually
reviewed and is subject to revision. Trend data prior to
any revisions must be considered in the context of
those changes.
• Not all states and local agencies provide the same data or
level of detail for a given year.
Data Sources
Summary data in this indicator were provided by EPA's
Office of Air Quality Planning and Standards, based on
biogenic and anthropogenic VOC emissions data in the
NEI (U.S. EPA, 2007b) (http://www.epa.gov/ttn/chief/
net/2002inventory.html). This indicator aggregates the
NEI data by source type (anthropogenic or biogenic),
source category, and EPA Region.
References
U.S. EPA (United States Environmental Protection
Agency). 2007a. Documentation for the final 2002 mobile
National Emissions Inventory, Version 3.
Exhibit 2-12. VOC emissions in the U.S. by
EPA Region, 1990 and 1996-20023
° 3
—R1
—R2
—R3
R4
-R5
R6
R7
R8
—R9
-R10
'96 '97 '98 '99 '00 '01 '02
Year
aData are presented for 1990
and 1996-2002, as datasets
from these inventory years are
fully up to date. Data are
available for inventory years
1991-1995, but these data have
not been updated to allow
comparison with data from
1990 and 1996-2002.
Data source: U.S. EPA, 2007b
EPA Regions
U.S. EPA. 2007b. Data from the 2002 National Emissions
Inventory, Version 3.0. Accessed 2007.
U.S. EPA. 2006. NEI quality assurance and data
augmentation for point sources. Research Triangle Park,
NC.
U.S. EPA. 2003a. Requirements for preparation, adoption,
and submittal of implementation plans: Definitions. Code
of Federal Regulations 40CFR51.100(s).
U.S. EPA. 2003b. National air quality and emissions trends
report—2003 special studies edition. EPA/454/R-03/005.
Research Triangle Park, NC.
EPA's 2008 Report on the Environment
2-21
-------
INDICATOR
Ambient Concentrations of Ozone
Ozone is a gas found in different parts of the atmosphere.
Ozone in the upper atmosphere, or stratosphere,
helps protect the Earth from the sun's harmful rays. (The
Ozone Levels over North America indicator, on page
2-54, describes trends in stratospheric ozone levels over the
U.S.) In the lowest level of the atmosphere, the tropo-
sphere, ozone is harmful to both human health and the
environment. For this reason, ozone is often described as
being "good up high and bad nearby" (U.S. EPA, 2003a).
Although some industrial sources release ozone directly
into the environment, most ground-level ozone forms in
the air from chemical reactions involving nitrogen oxides
(NO ), volatile organic compounds (VOCs), and sunlight.
Ozone levels are typically highest during the afternoon
hours of the summer months, when the influence of direct
sunlight is the greatest. These highest levels occur dur-
ing what is known as the "ozone season," which typically
occurs from May 1 to September 30 but whose time frame
varies by state (U.S. EPA, 2003b).
Variations in weather conditions play an important role
in determining ozone levels. Daily temperatures, rela-
tive humidity, and wind speed can affect ozone levels. In
general, warm dry weather is more conducive to ozone
formation than cool wet weather. Wind can affect both
the location and concentration of ozone pollution. NO
and VOC emissions can travel hundreds of miles on air
currents, forming ozone far from the original emissions
sources. Ozone also can travel long distances, affecting
areas far downwind. High winds tend to disperse pol-
lutants and can dilute ozone concentrations. However,
stagnant conditions or light winds allow pollution levels to
build up and become more concentrated.
Inhalation exposure to ozone has been linked to numer-
ous respiratory health effects, including acute reversible
decrements in lung function, airway inflammation, cough,
and pain when taking a deep breath. Ozone exposure can
aggravate lung diseases such as asthma, leading to increased
medication use and increased hospital admission and visits
to emergency rooms. In addition, evidence is highly sug-
gestive that ozone directly or indirectly contributes to
non-accidental and cardiopulmonary-related mortality, but
the underlying mechanisms by which such effects occur
have not been fully established (U.S. EPA, 2006). Although
people with lung disease are most susceptible to the effects
of ozone, even healthy people who are active outdoors can
suffer from ozone-related health effects. Further, evidence
suggests that older adults (more than 65 years old) appear to
be at excess risk of ozone-related mortality or hospitaliza-
tion (U.S. EPA, 2006). Elevated concentrations of ozone
can also affect vegetation and ecosystems, as the Ozone
Injury to Forest Plants indicator (p. 2-24) describes further
(U.S. EPA, 2006).
Exhibit 2-13. Ambient 8-hour ozone
concentrations in the U.S., 1978-20063
.- E 0.14
A. Ambient concentrations
co £
0.12
r L: 0.10
j= o S3 008
t ° "re
= ^ °
£ | | 0.06
|1 | °'04
CO £ O
•S -x " 0.02
~ 0.00
're g E
-a -Si a.
*- 3 a.
CO
0
90% of sites have concentrations below this line
10% of sites have concentrations below this line
'90-'92 '94-'96 '98-'00 '02-'04
Averaging period
B. Number of trend sites above NAAQS
G o
120
40
o
78-'80 '82-'84 '86-'88 '90-'92 '94-'96 '98-'00 '02-'04
Averaging period
E -
Coverage: 201 monitoring sites in 150 counties nationwide (out of
a total of 1,194 sites measuring ozone in 2006) that have sufficient
data to assess ozone trends since 1978.
bThe figure displays the 1997 NAAQS (0.08 ppm). Future versions of
the ROE will compare ozone concentrations to the recently
promulgated 2008 NAAQS (0.075 ppm) or to the NAAQS in effect at
the time.
Data source: U.S. EPA, 2007
This indicator presents ambient ground-level ozone
concentrations in parts per million (ppm) from 1978 to
2006. Data are shown for 8-hour averaging times, based
on continuous ozone monitoring data and consistent with
this pollutant's National Ambient Air Quality Standard
(NAAQS). The 8-hour standard is indicative of exposures
occurring over a sustained period of time (e.g., an outdoor
•worker's exposure over the course of a work day). Trends
for this indicator represent 201 sites in 150 counties nation-
wide that have data for the period of record in the State
2-22
EPA's 2008 Report on the Environment
-------
INDICATOI
Ambient Concentrations of Ozone (continued)
and Local Air Monitoring Stations net-work or by other
special purpose monitors. The indicator also displays trends
in ozone measurements in each EPA Region. This indica-
tor's exhibits display the corresponding 1997 NAAQS as a
point of reference, but the fact that the national or regional
concentrations fall below the standard does not mean that
all monitoring sites nationally or in any EPA Region also
are below the standard. The indicator displays trends in
the number of the 201 sites nation-wide at -which ozone
concentrations exceeded the level of the 1997 standard, but
this statistic is not displayed for each EPA Region.
Trends in ozone concentrations can be difficult to dis-
cern because of the year-to-year variations in the concen-
trations. By presenting data for rolling 3-year time periods,
this indicator smoothes out the "peaks" and "valleys" in
the trend, making it easier to see the long-term trend.
Three years is consistent -with the 3-year period used to
assess compliance -with the ozone standards. For the 8-hour
trends in this report, a 3-year average of the fourth highest
daily maximum 8-hour concentration in each year is used
to be consistent -with the 8-hour ozone standard.
What the Data Show
Between the 1978-1980 and 2004-2006 averaging peri-
ods, nation-wide fourth highest daily maximum 8-hour
ambient ozone concentrations decreased by 25 percent
(Exhibit 2-13, panel A). Although the 8-hour ozone levels
in 2004-2006 -were the lowest on record and the number
of trend sites measuring ozone concentrations above the
level of the 1997 8-hour NAAQS decreased by 75 percent
over the time frame covered in this indicator (Exhibit
2-13, panel B), ambient air monitoring data collected in
2006 and reported to EPA's Air Quality System indicate
that approximately 77 million people lived in counties
•where 8-hour average ozone concentrations are above
the level of the 1997 primary ozone NAAQS. Among the
ten EPA Regions, the most substantial declines in 8 hour
levels -were observed in EPA Regions that originally had
the highest ozone concentrations (EPA Regions 1 and 9)
(Exhibit 2-14). Over the entire period of record, Region
10 consistently showed the lowest Regional ozone levels.
Also shown in Exhibit 2-13 (panel A) are the 90th and
10th percentiles based on the distribution of statistics at
the monitoring sites. This provides additional graphical
representation of the variability of measured concentrations
across the monitoring sites for a given 3-year period. Thus,
the graphic displays the concentration range -where 80 per-
cent of measured values occurred for that 3-year period.
In summary, despite reductions in ambient concentra-
tions of ozone over the past quarter century and decreases in
the emissions of ozone precursors since 1990 (the Nitrogen
Oxides Emissions indicator, p. 2-16; the VOC Emissions
indicator, p. 2-20.), ozone remains one of the most persistent
and ubiquitous air pollution issues in the U.S.
Exhibit 2-14. Ambient 8-hour ozone
concentrations in the contiguous U.S. by EPA
Region, 1978-20063
'94-'96 '02-'04
Averaging period
Coverage: 201 monitoring
sites in the EPA Regions (out of
a total of 1,194 sites measuring
ozone in 2006) that have
sufficient data to assess ozone
trends since 1978.
bThe figure displays the 1997
NAAQS (0.08 ppm). Future
versions of the ROE will
compare ozone concentrations
to the recently promulgated
2008 NAAQS (0.075 ppm) or
to the NAAQS in effect at
the time.
Data source: U.S. EPA, 2007
EPA Regions
Indicator Limitations
• Short-term trends in ozone concentrations are often
highly dependent on meteorological conditions. This
complicates efforts to interpret data for any given year.
Air quality trends over the longer term are far less likely
to be influenced by unusual meteorological conditions.
• Because most of the monitoring sites are located in urban
areas, the trends might not accurately reflect conditions
outside the immediate urban monitoring areas.
• Because of the relatively small number of trend sites in
some EPA Regions, the regional trends are subject to
greater uncertainty than the national trends. Some EPA
Regions -with low average concentrations may include
areas -with high local concentrations, and vice versa.
• To ensure that long-term trends are based on a consistent
set of monitoring sites, selection criteria -were applied to
identify the subset of ozone monitoring sites -with sufficient
data to assess trends since 1978. Monitoring sites -without
sufficient data are not included in the trend analysis. Some
EPA's 2008 Report on the Environment
2-23
-------
INDICATOI
Ambient Concentrations of Ozone (continued)
excluded monitoring sites reported ozone concentrations
above the level of the ozone standard over the time frame
covered by this indicator. In 2006, for example, 187 moni-
toring sites (in addition to the trend sites shown in Exhibit
2-13, panel B) recorded ozone concentrations above the
level of the 1997 NAAQS, but did not have sufficient long-
term data to be included in this indicator.
Data Sources
Summary data in this indicator were provided by EPA's
Office of Air Quality Planning and Standards, based on
ozone ambient air monitoring data in EPA's Air Quality
System (U.S. EPA, 2007) (http://www.epa.gov/ttn/airs/
airsaqs/). National and regional trends in this indicator are
based on the subset of ozone monitoring stations that have
sufficient data to assess trends since 1978.
References
U.S. EPA (United States Environmental Protection
Agency). 2007. Data from the Air Quality System.
Accessed 2007.
U.S. EPA. 2006. Air quality criteria for ozone and related
photochemical oxidants. EPA/600/R-05/004aF-cF.
Research Triangle Park, NC.
U.S. EPA. 2003a. Ozone: Good up high, bad nearby.
EPA/451/K-03/001. Washington, DC.
U.S. EPA. 2003b. Latest findings on national air qual-
ity—2002 status and trends. EPA/454/K-03/001. Research
Triangle Park, NC.
INDICATOR
Ozone Injury to Forest Plants
Air pollution can have note-worthy cumulative impacts
on forested ecosystems by affecting regeneration,
productivity, and species composition (U.S. EPA, 2006). In
the U.S., ozone in the lower atmosphere is one of the pol-
lutants of primary concern. Ozone injury to forest plants
can be diagnosed by examination of plant leaves. Foliar
injury is usually the first visible sign of injury to plants
from ozone exposure and indicates impaired physiological
processes in the leaves (Grulke, 2003).
This indicator is based on data from the U.S. Department
of Agriculture (USDA) Forest Service Forest Inventory and
Analysis (FIA) program. As part of its Phase 3 program,
formerly known as Forest Health Monitoring, FIA examines
ozone injury to ozone-sensitive plant species at ground moni-
toring sites in forest land across the country. For this indicator,
forest land does not include woodlots and urban trees. Sites
are selected using a systematic sampling grid, based on a global
sampling design (White et al., 1992; Smith et al., 2003). At
each site that has at least 30 individual plants of at least three
ozone-sensitive species and enough open space to ensure that
sensitive plants are not protected from exposure by the forest
canopy, FIA looks for damage on the foliage of ozone-sensitive
forest plant species. Because ozone injury is cumulative over
the course of the growing season, examinations are conducted
in July and August, when ozone injury is typically highest.
Monitoring of ozone injury to plants by the USDA Forest
Service has expanded over the last 10 years from monitoring
sites in ten states in 1994 to nearly 1,000 monitoring sites
in 41 states in 2002. The data underlying this indicator are
based on averages of all observations collected in 2002, the
latest year for which data are publicly available, and are bro-
ken down by EPA Region. Ozone damage to forest plants is
classified using a subjective five-category biosite index based
on expert opinion, but designed to be equivalent from site
to site. Ranges of biosite values translate to no injury, low or
moderate foliar injury (visible foliar injury to highly sensi-
tive or moderately sensitive plants, respectively), and high
or severe foliar injury, which would be expected to result in
tree-level or ecosystem-level responses, respectively (Coul-
ston et al., 2004; U.S. EPA, 2006).
What the Data Show
There is considerable regional variation in ozone injury to
sensitive plants (Exhibit 2-15). The highest percentages of
observed high and severe foliar injury, which are most likely
to be associated with tree or ecosystem-level responses,
are primarily found in the Mid-Atlantic and Southeast
regions. In EPA Region 3, 12 percent of ozone-sensitive
plants showed signs of high or severe foliar damage, and in
Regions 2 and 4, the values were 10 percent and 7 percent,
respectively. The sum of high and severe ozone injury
ranged from 2 percent to 4 percent in EPA Regions 1, 7, and
9; and no high or severe foliar damage was observed in EPA
Regions 5, 6, 8, and 10. The percentage of sites showing no
damage was greater than 55 percent in every EPA Region,
and no ozone-related foliar damage was observed at any of
the 129 biosites in EPA Regions 8 and 10.
2-24
EPA's 2008 Report on the Environment
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INDICATOI
Ozone Injury to Forest Plants (continued)
Indicator Limitations
• Field and laboratory studies were reviewed to identify
the forest plant species in each region that are highly sen-
sitive to ozone air pollution. Other forest plant species,
or even genetic variants of the same species, may not be
harmed at ozone levels that cause effects on the selected
ozone-sensitive species.
• Because species distributions vary regionally, different
ozone-sensitive plant species were examined in different
parts of the country. These target species could vary with
respect to ozone sensitivity, which might account for
some of the apparent differences in ozone injury among
EPA Regions.
• Ozone damage to foliage is considerably reduced under
conditions of low soil moisture, but most of the vari-
ability in the index (70 percent) was explained by ozone
concentration (Smith et al., 2003).
• Ozone may have other adverse impacts on plants (e.g.,
reduced productivity) that do not show signs of visible
foliar injury (U.S. EPA, 2006).
• Though FIA has extensive spatial coverage based on a
robust sample design, not all forested areas in the U.S.
are monitored for ozone injury.
• Even though the biosite data have been collected over
multiple years, most biosites were not monitored over
the entire period, so these data cannot provide more
than a baseline for future trends.
Data Sources
Data were provided by the USDA Forest Service's Ozone
Biomonitoring Program, which maintains a database of
plant injury statistics by state (USDA Forest Service, 2006)
(http://nrs.fs.fed.us/fia/topics/ozone/data/). This indicator
aggregates the state data by EPA Region.
References
Coulston, J.W., K.H. Rntters, and G.C. Smith. 2004. A
preliminary assessment of the Montreal process indica-
tors of air pollution for the United States. Environ. Monit.
Assess. 95:57-74.
Grulke, N.E. 2003. The physiological basis of ozone injury
assessment attributes in Sierran conifers. In: Bytnerowicz,
A., MJ. Arbaugh, and R. Alonso, eds. Ozone air pollution
in the Sierra Nevada: Distribution and effects on forests.
New York, NY: Elsevier Science, Ltd. pp. 55-81.
Smith, G., J. Coulston, E. Jepsen, and T. Prichard. 2003. A
national ozone biomonitoring program—results from field
surveys of ozone sensitive plants in Northeastern forests
(1994-2000). Environ. Monit. Assess. 87:271-291.
USDA Forest Service (United States Department of Agri-
culture Forest Service). 2006. Ozone bioindicator data.
Accessed 2006.
Exhibit :
the U.S.
Region 1
(54 sites)
Region 2
(42 sites)
Region 3
(111 sites)
Region 4
(227 sites)
Region 5
(180 sites)
Region 6
(59 sites)
Region 7
(63 sites)
Region 8
(72 sites)
Region 9
(80 sites)
Region 10
(57 sites)
Coverage:
located in A
bTotals may
rounding.
Data sourc
2006
M5. Ozone injury to forest plants in
by EPA Region, 2002ab
Degree of injury:
None Low Moderate High Severe
'ercent of monitoring sites in each category:
68.5 16.7 11.1
61.9 21.4 7.1 7
55.9 18.0 14.4 7.
75.3 10.1 7.0 "
75.6 18.3 6
-3.7
1 2.4
1 4.5
13.5
H.O
1
94.9
85.7 9.5
I5'1
3.2
1.6
100.0
76.3 12.5 8.8
1.3
1.3
100.0
345 monitoring sites, EPA Regions
1 states.
not add to 100% due to 0
' SS
9°
U.S. EPA (United States Environmental Protection
Agency). 2006. Air quality criteria for ozone and related
photochemical oxidants. EPA/600/R-05/004aF-cF.
Research Triangle Park, NC.
White, D., AJ. Kimerlmg, and W.S. Overton. 1992. Car-
tographic and geometric component of a global sampling
design for environmental monitoring. Cartogr. Geograph.
Info. Sys. 19:5-22.
EPA's 2008 Report on the Environment
2-25
-------
INDICATOR
Particulate Matter Emissions
u
Particulate matter" (PM) is the general term used to
describe solid particles and liquid droplets found in the
air. The composition and size of these airborne particles
and droplets vary. Some particles are large enough to be
seen as dust or dirt, while others are so small they can only
be seen using a powerful microscope. Two size ranges,
known as PM1Q and PM2 5, are widely monitored, both at
major emissions sources and in ambient air. PM1Q includes
particles that have aerodynamic diameters less than or
equal to 10 microns ((am), approximately equal to one-
seventh the diameter of human hair. PM25 is the subset of
PM1Q particles that have aerodynamic diameters less than
or equal to 2.5 (am.
Particles within the two size ranges behave differently in
the atmosphere. PM25, or fine particles, can remain air-
borne for long periods and travel hundreds of miles. Coarse
particles, or the subset of PM1Q that is larger than 2.5 (am,
do not remain airborne as long and their spatial impact is
typically limited because they tend to deposit on the ground
downwind of emissions sources. Larger coarse particles are
not readily transported across urban or broader areas because
they are generally too large to follow air streams and they
tend to be removed easily on contact with surfaces. In
short, as the particle size increases, the amount of time the
particles remain airborne decreases. The PM Concentrations
indicator (p. 2-29) describes the various ways PM can harm
human health and the environment (U.S. EPA, 2004).
PM can be emitted directly or formed in the atmosphere.
"Primary" particles are those released directly to the
atmosphere. These include dust from roads and soot from
combustion sources. In general, coarse PM is composed
largely of primary particles. "Secondary" particles, on the
other hand, are formed in the atmosphere from chemical
reactions involving primary gaseous emissions. Thus, these
particles can form at locations distant from the sources
that release the precursor gases. Examples include sulfates
formed from sulfur dioxide emissions from power plants
and industrial facilities and nitrates formed from nitrogen
oxides released from power plants, mobile sources, and
other combustion sources. Unlike coarse PM, a much
greater portion of fine PM (PM25) contains secondary
particles (U.S. EPA, 2004).
This indicator presents trends in annual average pri-
mary PM emissions data tracked by the National Emis-
sions Inventory (NEI). The NEI tracks emission rate data,
both measured and estimated, for primary particles only.
Because secondary particles are not released directly from
stacks, the NEI instead tracks the precursors that contrib-
ute to formation of secondary particles. These precursors
include nitrogen oxides, sulfur dioxide, ammonia, and
other gases (e.g., particle-producing organic gases), some
of which are addressed in separate indicators (the Nitrogen
Oxides Emissions indicator, p. 2-16; the Sulfur Dioxide
Exhibit 2-16. PM-io emissions in the U.S. by
source category, 1990 and 1996-2002
3.5
__ 3.0
S 2.5
o
= 2.0
_§_
« 1.5
1 1.0
E
m 0.5
A. Anthropogenic PM-m emissions by source category3 f
-
_A
Fuel combustion
Other industrial processes
On-road vehicles
Nonroad vehicles and engines
'90
'96 '97
'99 '00
'01
'02
Year
B. Relative amounts of
emissions from anthropogenic
and other sources, 2002
Miscellaneous
and natural
sources
26%
Anthropogenic
14%
aData are presented for 1990
and 1996-2002, as datasets
from these inventory years
are fully up to date. Data are
available for inventory years
1991-1995, but these data
have not been updated to
allow comparison with data
from 1990 and 1996-2002.
Starting in 1999, EPA began
tracking condensable
particulate emissions
separately from filterable
particulate emissions. In
order to display data
generated using a consistent methodology, emissions of
condensable particulate from 1990 to 2002 are not included in
Panel A. However, condensable particulate emissions are
included in Panel B.
Data source: U.S. EPA, 2007b
\ /
Fugitive dust
60%
Emissions indicator, p. 2-34). Particles formed through
secondary processes are not included in this indicator.
Primary emissions of PM can exist as solid or liquid mat-
ter (the "filterable" portion) or as gases (the "condensable"
portion). Data for the condensable portion exist only for
the years 1999 to 2002. To allow for a valid comparison
of emissions trends from 1990 to 2002, only data for the
filterable portion of PM1Q and PM2 5 are included in the
trend graphs. Condensables are, however, included in the
inset pie charts shown in Exhibits 2-16 and 2-18 (i.e., panel
B in both exhibits).
All emissions data presented in this indicator are taken
from the NEI. Primary particulate emissions data are
presented for the traditionally inventoried anthropogenic
source categories: (1) "Fuel combustion," which includes
2-26
EPA's 2008 Report on the Environment
-------
INDICATOI
Particulate Matter Emissions (continued)
emissions from coal-, gas-, and oil-fired power plants and
industrial, commercial, and institutional sources, as well
as residential heaters and boilers; (2) "Other industrial
processes," which includes chemical production, petroleum
refining, metals production, and processes other than fuel
combustion; (3) "On-road vehicles," which includes cars,
trucks, buses, and motorcycles; and (4) "Nonroad vehicles
and engines," such as farm and construction equipment,
lawnmowers, chainsaws, boats, ships, snowmobiles, air-
craft, and others. For 2002 only, this indicator includes a
comparison of these anthropogenic sources with emissions
from miscellaneous and natural sources, such as agriculture
and forestry, wildfires and managed burning, and fugitive
dust from paved and unpaved roads. Biogenic emissions
•were estimated using the Biogenic Emissions Inventory
System Model, Version 3.12, with data from the Biogenic
Emissions Landcover Database and 2001 annual meteoro-
logical data. The NEI also documents estimates of primary
emissions from fugitive dust and miscellaneous sources.
The NEI is a composite of data from many different
sources, including industry and numerous state, tribal, and
local agencies. Different data sources use different data
collection methods, and many of the emissions data are
based on estimates rather than actual measurements. For
most fuel combustion sources and industrial sources, emis-
sions are estimated using emission factors. Emissions from
on-road and nonroad sources were estimated using EPA-
approved modeling approaches (U.S. EPA, 2007a).
NEI data have been collected since 1990 and cover all
50 states and their counties, D.C., the U.S. territories of
Puerto Rico and Virgin Islands, and some of the territories
of federally recognized American Indian nations. Data are
presented for 1990 and the years from 1996 to 2002; prior
to 1996, only the 1990 data have been updated to be com-
parable to the more recent inventories.
What the Data Show
Primary PM10 Emissions Trends
Estimated primary PM1Q emissions from anthropogenic
sources decreased 27 percent nationally between 1990 and
2002 (Exhibit 2-16, panel A). Of these sources, those in
the fuel combustion category saw the largest absolute and
relative decrease in emissions (656,000 tons; 55 percent).
Primary PM1Q emissions from the group of sources includ-
ing miscellaneous and natural sources and fugitive dust
•were estimated to account for 86 percent of total primary
PM1Q emissions (including condensables from stationary and
mobile sources) in 2002, the majority of which was attribut-
able to fugitive dust from roads (Exhibit 2-16, panel B).
Changes in estimated primary anthropogenic PM1Q
emissions from 1990 to 2002 varied widely among EPA
Regions, ranging from an increase of 16 percent (Region
8) to a decrease of 75 percent (Region 2) (Exhibit 2-17).
Exhibit 2-17. PM-io emissions in the U.S. by
EPA Region, 1990 and 1996-2002ab
_ 70°
o 600
1 50°
£ 400
| 300
.22 200
LLJ
100
0
—R1
—R2
-R3
-R4
-R5
R6
R7
R8
—R9
-R10
'96 '97 '98 '99 '00 '01
Year
'02
aData are presented for 1990 _ EPA Regions
and 1996-2002, as datasets
from these inventory years are
fully up to date. Data are
available for inventory years
1991-1995, but these data
have not been updated to allow
comparison with data from
1990 and 1996-2002.
Starting in 1999, EPA began tracking condensable particulate
emissions separately from filterable particulate emissions. In
order to display data generated using a consistent methodology,
emissions of condensable particulate from 1999 to 2002 are not
included in this figure.
Data source: U.S. EPA, 2007b
Primary PM25 Emissions Trends
Estimated primary PM2 B emissions from anthropogenic
sources decreased 44 percent nationally between 1990 and
2002 (Exhibit 2-18, panel A). The largest absolute and
relative decline in PM2 B was seen in the fuel combustion
source category (621,000 tons; 68 percent). Primary emis-
sions from the group of sources including miscellaneous
and natural sources and fugitive dust were estimated to
account for 64 percent of the total PM2 B emissions (includ-
ing condensables from stationary and mobile sources)
nationally in 2002 (Exhibit 2-18, panel B).
Primary anthropogenic PM2 B emissions decreased in all
ten EPA Regions from 1990 to 2002, with percent reduc-
tions ranging from 21 percent (Region 4) to 71 percent
(Region 2) (Exhibit 2-19).
Indicator Limitations
• Comparable PM emissions estimates through the
NEI are available only for 1990 and 1996-2002. Data
for 1991-1995 are not provided due to differences in
EPA's 2008 Report on the Environment
2-27
-------
INDICATOI
Particulate Matter Emissions (continued)
Exhibit 2-18. PM2.5 emissions in the U.S. by
source category, 1990 and 1996-2002
2.5
"«• 2.0
o
I 1'5
JE,
£ 1.0
o
,1 0.5
A. Anthropogenic PM2.5 emissions by source category3
o.oU—V
Other industrial processes
On-road vehicles
Nonroad vehicles and engines
'90
'96
'97
'00
'02
Year
B. Relative amounts of PM2.5
emissions from anthropogenic
and other sources, 2002
Miscellaneous
and natural
sources
33%
Anthropogenic
36%
aData are presented for 1990
and 1996-2002, as datasets
from these inventory years
are fully up to date. Data are
available for inventory years
1991-1995, but these data
have not been updated to
allow comparison with data
from 1990 and 1996-2002.
Starting in 1999, EPA began
tracking condensable
particulate emissions
separately from filterable
particulate emissions. In
order to display data
generated using a consistent methodology, emissions of
condensable particulate from 1990 to 2002 are not included in
Panel A. However, condensable particulate emissions are included
in Panel B.
Data source: U.S. EPA, 2007b
^
Fugitive dust
31%
emissions estimation methodologies from other inventory
years, which could lead to improper trend assessments.
Because the emissions indicators focus on sources of
anthropogenic origin, PM emissions from miscella-
neous sources (e.g., wildfires) are not included in the
trend line. Details on emissions from these sources can
be found by downloading 2002 NEI inventory data for
the "nonpoint sector" (http://www.epa.gov/ttn/chief/
net/2002inventory.html).
The emissions data for PM are largely based on estimates
that employ emission factors generated from empirical
and engineering studies, rather than on actual measure-
ments of PM emissions. Although these estimates are
generated using -well-established approaches, the esti-
mates have uncertainties inherent in the emission factors
Exhibit 2-19. PIVb.s emissions in the U.S. by
EPA Region, 1990 and 1996-2002ab
o 400
300
200
100
'97 '98 '99 '00 '01 '02
Year
aData are presented for 1990 EPA Regions
and 1996-2002, as datasets
from these inventory years are
fully up to date. Data are
available for inventory years
1991-1995, but these data have
not been updated to allow
comparison with data from
1990 and 1996-2002.
Starting in 1999, EPA began tracking condensable particulate
emissions separately from filterable particulate emissions. In
order to display data generated using a consistent methodology,
emissions of condensable particulate from 1999 to 2002 are not
included in this figure.
Data source: U.S. EPA, 2007b
and emissions models used to represent sources for which
emissions have not been directly measured.
• The methodology for estimating emissions is continually
reviewed and is subject to revision. Trend data prior to
these revisions must be considered in the context of those
changes.
• The indicator tracks primary PM emissions. Particles
that form in the air through secondary processes are not
included in this indicator, but are considered in the PM
Concentrations indicator (p. 2-29).
• Not all states and local agencies provide the same data or
level of detail for a given year.
Data Sources
Summary data in this indicator were provided by EPA's
Office of Air Quality Planning and Standards, based on
biogenic and anthropogenic PM emissions data in the
NEI (U.S. EPA, 2007b) (http://www.epa.gov/ttn/chief/
net/2002inventory.html). This indicator aggregates the
2-28
EPA's 2008 Report on the Environment
-------
INDICATOI
Particulate Matter Emissions (continued)
NEI data by source type (anthropogenic or biogenic),
source category, and EPA Region.
References
U.S. EPA (United States Environmental Protection
Agency). 2007a. Documentation for the final 2002 mobile
National Emissions Inventory, Version 3.
U.S. EPA. 2007b. Data from the 2002 National Emissions
Inventory, Version 3.0. Accessed 2007.
U.S. EPA. 2004. Air quality criteria for particulate mat-
ter (October 2004). EPA 600/P-99/002aF-bF. Research
Triangle Park, NC.
mbient Concentrations of Particulate
F^articulate matter" (PM) is the general term used for a
mixture of solid particles and liquid droplets found in
the air. Airborne PM comes from many different sources.
"Primary" particles are released directly into the atmo-
sphere from sources such as cars, trucks, heavy equipment,
forest fires, and burning waste. Primary particles also
consist of crustal material from sources such as unpaved
roads, stone crushing, construction sites, and metallurgi-
cal operations. "Secondary" particles are formed in the air
from reactions involving precursor chemicals such as sul-
fates (which are formed from sulfur dioxide emissions from
power plants and industrial facilities), nitrates (which are
formed from nitrogen dioxide emissions from cars, trucks,
and power plants), and carbon-containing reactive organic
gas emissions from cars, trucks, industrial facilities, forest
fires, and biogenic sources such as trees.
Ambient air monitoring stations throughout the country
measure air concentrations of two size ranges of particles:
PM25 and PM1Q. PM25 consists of "fine particles" with
aerodynamic diameters less than or equal to 2.5 microns
((am). PM1Q includes both fine particles (PM25) and "coarse
particles," which is the subset of PM1Q that is larger than
2.5 (am and smaller than 10 (am. The chemical makeup of
particles varies across the U.S. For example, fine particles
in the eastern half of the US contain more sulfates than
those in the West, while fine particles in southern Califor-
nia contain more nitrates than those in other areas of the
U.S. Carbon is a substantial component of fine particles
everywhere (U.S. EPA, 2004a).
Fine particles also have seasonal patterns. PM2 5 values in
the eastern half of the U.S. are typically higher in the third
calendar quarter (July-September), when sulfates are more
commonly formed from sulfur dioxide emissions from power
plants in that part of the country. Fine particle concentrations
tend to be higher in the fourth calendar quarter (October-
December) in many areas of the West, in part because fine
Exhibit 2-20. Ambient 24-hour
concentrations in the U.S., 1988-20063
175
,_ 150
= 125
25
0
'!
w J= 35
IE "53 30
1 £
11^25
A. Ambient concentrations
l\IAAQS = 150ug/m3
90% of sites have concentrations below this line
10% of sites have
concentrations below this line
'90 '92 '94 '96
'00 '02 '04 '06
Year
B. Number of trend sites above NAAQS
'88 '90 '92 '94
'96 '98 '00 '02 '04 '06
Year
Coverage: 301 monitoring sites in 199 counties nationwide (out of a
total of 902 sites measuring PM10 in 2006) that have sufficient data
to assess PM-|0 trends since 1988.
Data source: U.S. EPA, 2007
EPA's 2008 Report on the Environment
2-29
-------
INDICATOI
Ambient Concentrations of Particulate Matter (continued)
Exhibit 2-21. Ambient 24-hour
concentrations in the contiguous U.S. by EPA
Region, 1988-20063
180
160
— 140
1,120
~STlOO
o
1 £ 80
| 60
o
« 40
20
0
R1
R2
R3
R4
-R5
R6
R7
R8
-R9
-R10
-Nat'l
'90 '92 '94 '96 '9i
Year
Coverage: 292 monitoring sites
in the EPA Regions (out of a total
of 902 sites measuring PM-|0 in
2006) that have sufficient data to
assess PM-|0 trends since 1988.
Data source: U.S. EPA, 2007
'00 '02 '04 '06
EPA Regions
particle nitrates are more readily formed in cooler weather,
and wood stove and fireplace use produces more carbon.
Many recent epidemiologic studies show statistically
significant associations of various ambient PM indicators
(e.g., coarse or fine particulate, short-term or long-term
concentrations) with a variety of cardiovascular and respira-
tory health endpoints, including mortality, hospital admis-
sions, emergency department visits, other medical visits,
respiratory illness and symptoms, and physiologic changes
in pulmonary function (U.S. EPA, 2004b). Sensitive groups
that appear to be at greatest risk to such PM effects include
older adults, individuals with cardiopulmonary disease such
as asthma or congestive heart disease, and children (U.S.
EPA, 2004b). Unlike other criteria pollutants, PM is not a
single specific chemical entity, but rather a mixture of par-
ticles from different sources with different sizes and chemical
compositions. Toxicological studies suggest that some air-
borne particles are more toxic than others, due to differences
in their chemical composition—a topic that is thoroughly
reviewed in other publications (e.g., U.S. EPA, 2004b).
PM also can cause adverse impacts to the environment. Fine
particles are the major cause of reduced visibility in parts of the
U.S., including many National Parks and Wilderness Areas
(the Regional Haze indicator, p. 2-33). PM deposition affects
vegetation and ecosystems by altering nutrient and chemical
cycles in soils and surface water. For example, deposition of
Exhibit 2-22. Ambient annual PIVhs concentrations
in the U.S., 1999-20063
CD Q5
re'.S
g 3
« S;
20
15
A. Ambient concentrations
£ != ^ 10
90% of sites have concentrations below this line
NAAQS = 15 ug/m3
Median
Y
I
Average
10% of sites have concentrations below this line
o
'99-'01
'00-' 02 '01-'03 '02-'04 '03-'05 '04-'06
Averaging period
B. Number of trend sites above NAAQS
'99-'01 '00-'02 '01-'03 '02-'04 '03-'05 '04-'06
Averaging period
Coverage: 752 monitoring sites in 508 counties nationwide (out of a
total of 786 sites measuring PM2.5 in 2006) that have sufficient data
to assess PM2.5 trends since 1999.
Data source: U.S. EPA, 2007
particles containing nitrogen and sulfur may change the nutri-
ent balance and acidity of aquatic environments so that species
composition and buffering capacity change (the Lake and
Stream Acidity indicator, p. 2-42.). Some particles that deposit
onto plant leaves can corrode leaf surfaces or interfere with
plant metabolism. PM also causes soiling and erosion damage
to materials, including monuments, statues, and other objects
of cultural importance (U.S. EPA, 2004b).
This indicator presents trends in PM1Q and PM2 5 con-
centrations, using averaging times consistent with the
pollutants' corresponding National Ambient Air Quality
Standards (NAAQS). For PMW, trend data from 1988 to
2006 are presented for the second highest 24-hour concen-
trations measured at the trend sites during each calendar
year. ForPM25, trend data from 1999 to 2006 are presented
for seasonally -weighted annual average concentrations and
2-30
EPA's 2008 Report on the Environment
-------
INDICATOI
Ambient Concentrations of Particulate Matter (continued)
Exhibit 2-23. Ambient annual PIVb.s concentrations
in the contiguous U.S. by EPA Region, 1999-20063
20
« S^15
§ g-g
c O O)
= CD =i
re CD
CD ^^ ro -i n
•" ^- CD IU
= re j±; ,-
ro 4^ a: 0
W "
re =
CD O
CO U
NAAQS = 15 ug/m3
0
'99-'01 '00-'02
R1
R2
R3
R4
-R5
R6
R7
R8
-R9
-R10
-Nat'l
'01-'03 '02-'04
Averaging period
'03-'05 '04-'06
Coverage: 736 monitoring
sites in the EPA Regions (out
of a total of 786 sites
measuring PM2.5 in 2006) that
have sufficient data to assess
PM2.5 trends since 1999.
Data source: U.S. EPA, 2007
EPA Regions
for the 98th percentiles of 24-hour average concentrations
measured at the trend sites over three consecutive calen-
dar years. Trend data are based on measurements from the
State and Local Air Monitoring Stations net-work and from
other special purpose monitors. This indicator presents PM1Q
trends for 301 monitoring sites in 199 counties nation-wide
and PM2 B trends for 752 monitoring sites in 508 counties
nation-wide. For both PM1Q and PM2 5, the indicator displays
trends for the entire nation and for the ten EPA Regions.
The indicator's exhibits display the pollutants' NAAQS as
points of reference. However, the fact that the national val-
ues or those shown for EPA Regions fall below the standards
does not mean that all monitoring sites nationally or in any
particular EPA Region also are below the standards. The
indicator displays trends in the number of PM1Q monitoring
sites and PM2 B monitoring sites nation-wide that recorded
ambient air concentrations above the level of the standards,
but these statistics are not displayed for each EPA Region.
What the Data Show
PM10 Concentration Trends
In 2006, the national 24-hour PM1Q concentration (based on
the second highest 24-hour concentration at each site) -was
37 percent lower than the average 1988 level (Exhibit 2-20,
panel A). Additionally, of the 301 sites used to determine
this trend (out of 902 total monitoring sites that -were oper-
ating in 2006), the number reporting PM1Q concentrations
Exhibit 2-24. Ambient 24-hour
concentrations in the U.S., 1999-20063
60
45
30
B g 15
o
A. Ambient concentrations
90% of sites have
concentrations below this line
NAAQS = 35 ug/nf
10% of sites have
concentrations below this line
'99-'01
'00-'02
'01-'03 '02-'04
Averaging period
'03-'05
'04-'06
B. Number of trend sites above NAAQS
£ §-
99-'01 '00-'02 '01-'03 '02-'04 '03-'05 '04-'06
5 o
'- ° Averaging period
Coverage: 752 monitoring sites in 508 counties nationwide (out of a
total of 811 sites measuring PM2.5 in 2006) that have sufficient data
to assess PM2.5 trends since 1999.
Data source: U.S. EPA, 2007
between 1988 and 2006 (Exhibit 2-20, panel B). All EPA
Regions experienced a steady decrease in 24-hour PM1Q lev-
els over this period (Exhibit 2-21). EPA Region 10 showed
the greatest relative decrease (68 percent) since 1988.
Also shown in Exhibit 2-20 (panel A) are the 90th and
10th percentiles based on the distribution of annual statistics
at the monitoring sites. This provides additional graphical
representation of the distribution of measured concentra-
tions across the monitoring sites for a given year. Thus, the
graphic displays the concentration range -where 80 percent
of measured values occurred for that year. (Note that this
presentation style also applies to panel A in Exhibits 2-22
and 2-24, discussed below.)
PM25 Concentration Trends
Seasonally weighted average PM concentrations over the
above the level of the 24-hour standard declined 78 percent 2004-2006 averaging period were the lowest since nationwide
EPA's 2008 Report on the Environment
2-31
-------
INDICATOI
Ambient Concentrations of Particulate Matter (continued)
Exhibit 2-25. Ambient 24-hour
concentrations in the contiguous U.S. by EPA
Region, 1999-2006a
• 60
45
2-s 30
—
U.S. EPA. 2004a. The particle pollution report: Cur-
rent understanding of air quality and emissions through
2003. EPA 454/R-04/002. Research Triangle Park, NC.
U.S. EPA. 2004b. Air quality criteria for particulate mat-
ter (October 2004). EPA 600/P-99/002aF-bF. Research
Triangle Park, NC.
*
2-32
EPA's 2008 Report on the Environment
-------
INDICATOI
Regional Haze
Visibility impairment occurs when air pollution, especially
particles, scatter and absorb light. The resulting haze
not only limits the distance one can see, but also degrades
the color, clarity, and contrast of scenes. As the PM Con-
centrations indicator (p. 2-29) describes further, the same
pollutants that impair visibility are linked to serious health
effects. Visibility impairment occurs throughout the coun-
try, including both urban and rural areas. Regional haze is
visibility impairment caused by the cumulative air pollutant
emissions from numerous sources over a wide geographic
area (U.S. EPA, 2004a). Regional haze has been identi-
fied as an important issue for all of the National Parks and
Wilderness Areas, such as the Grand Canyon, Great Smoky
Mountains, Mount Rainier, Shenandoah, Yellowstone, and
Yosemite National Parks (U.S. EPA, 2003).
The particles that impair visibility include both primary
and secondary pollutants. The primary pollutants of con-
cern are particles that are emitted directly into the atmo-
sphere, such as dust from roads or soot (elemental carbon)
from combustion sources (e.g., wood combustion). Sec-
ondary pollutants of concern are particles that form in the
atmosphere from chemical reactions and physical processes,
such as sulfates (formed from sulfur dioxide emissions from
power plants and other industrial facilities) and nitrates
(formed from nitrogen oxides emitted from power plants,
automobiles, and other types of combustion sources).
Humidity can increase the effect of pollution on visibil-
ity, causing some particles to become more efficient at scat-
tering light and impairing visibility (U.S. EPA, 2003). In
the eastern U.S., where annual average relative humidity
levels are between 70 percent and 80 percent, reduced vis-
ibility mainly results from secondarily formed sulfates and
high humidity, along with a somewhat lower contribu-
tion from organic carbon and nitrates (U.S. EPA, 2004b).
The effect of humidity is particularly strong in summer.
Humidity is less of a factor in the West, as average val-
ues are generally between 50 percent and 60 percent. In
•western states, primary emissions from sources like wood
smoke and nitrates contribute a large percentage of the
total particulate loading, though secondarily formed sul-
fates also contribute to visibility impairment. Without the
effects of anthropogenic sources of pollution, the annual
average natural visual range in the U.S. would vary with
location, and is estimated to range from 75 to 150 km (45
to 90 miles) in the East and from 200 to 300 km (120 to
180 miles) in the West (U.S. EPA, 2003).
This indicator reports visibility estimates calculated from
measurements of particulate matter (PM) constituents
collected at 38 monitoring sites between 1992 and 2004
at National Parks, Wilderness Areas, and other protected
sites under the Interagency Monitoring of Protected Visual
Environments (IMPROVE) net-work. Values are presented
Exhibit 2-26. Visibility in selected National Parks and Wilderness Areas in the U.S., 1992-2004ab
A. Western U.S. B. Eastern U.S.
300
250
1^ 200
to
5 150
« 100
50
Best visibility days
Mid-range visibility days
_Worst visibility days
Best visibility days
Mid-range visibility days
Worst visibility days
'92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04
Year
Coverage: 28 monitoring sites in the western U.S. and 10 monitoring sites in the eastern U.S. with sufficient
data to assess visibility trends from 1992 to 2004.
Visual ranges are calculated from the measured levels of different components within airborne particles and
these components' light extinction efficiencies.
Data source: IMPROVE, 2007
Monitoring sites
•/.': .ij jj?
'" y*: taff
-.jiSi^Eas,
—i H
EPA's 2008 Report on the Environment
2-33
-------
INDICATOR
Regional Haze (continued)
for 10 Eastern (east of 100 degrees west longitude) sites
and 28 Western (west of 100 degrees west longitude) sites.
Visibility, expressed as visual range, is calculated from the
measured levels of different components within airborne
particles and these components' light extinction efficiencies.
The IMPROVE algorithm (Debell et al, 2006) includes an
adjustment for ammonium sulfate and ammonium nitrate
to account for their adsorption of water vapor from the
atmosphere under elevated relative humidity conditions.
The IMPROVE particle data are generated by laboratory
analysis of 24-hour duration filter samples collected at each
site on a one-day-in-three schedule. This indicator tracks
visibility in three categories: worst visibility conditions (the
average of the 20 percent worst visibility days); best visibil-
ity conditions (the average of the 20 percent best visibility
days); and mid-range visibility conditions (the average of the
remaining 60 percent of days).
What the Data Show
On average, the best visibility in selected National Parks
and Wilderness Areas in the East, as calculated from the
measured concentrations of components of PM, is only
slightly better than the worst visibility in selected National
Parks and Wilderness Areas in the West (Exhibit 2-26).
In 2004, the average visual range for the worst days in the
East was 31 km (19 miles), compared to 137 km (85 miles)
for the best visibility days. In the West, the average visual
range in 2004 extended from 109 km (68 miles) on the
•worst days to 260 km (162 miles) on the best days. In both
regions, the average visual range in selected National Parks
and Wilderness Areas increased since 1992 for worst, mid-
range, and best visibility days. The increased visual ranges
between 1992 and 2004 for mid-range visibility days were
46 percent in the East and 14 percent in the West.
Indicator Limitations
• These data represent visibility in a sampling of selected
National Parks and Wilderness Areas and are not repre-
sentative of other rural or urban areas.
Data Sources
Summary data in this indicator were provided by the
National Park Service Air Quality Division, based on ambi-
ent air monitoring data collected as part of the IMPROVE
net-work (IMPROVE, 2007) and a computational algorithm
last updated in August 2007 (http://vista.cira.colostate.
edu/views/Web/IMPROVE/SummaryData.aspx). Vis-
ibility trends in this indicator are derived from the subset
of IMPROVE monitoring stations outside urban areas that
have sufficient data to assess trends between 1992 and 2004.
References
Debell, L.J., K.A. Gebhart, W.C. Malm, M.L. Pitchford,
B.A. Schichtel, and W.H. White. 2006. Spatial and seasonal
patterns and temporal visibility of haze and its constituents
in the United States: Report IV
IMPROVE (Interagency Monitoring of Protected Visual
Environments). 2007. Data from the IMPROVE network
based on the "New IMPROVE algorithm" (updated
August, 2007). Accessed 2007.
U.S. EPA (United States Environmental Protection
Agency). 2004a. The particle pollution report: Current
understanding of air quality and emissions through 2003.
EPA/454/R-04/002. Research Triangle Park, NC.
U.S. EPA. 2004b. The ozone report: Measuring progress
through 2003. EPA/454/K-04/001. Research Triangle
Park, NC.
U.S. EPA. 2003. Latest findings on national air quality
—2002 status and trends. EPA/454/K-03/001. Research
Triangle Park, NC.
INDICATOR
lulfur Dioxide Emissions
Sulfur dioxide (SO2) belongs to the family of sulfur
oxide (SO ) gases. These gases are formed when fuel
containing sulfur (mainly coal and oil) is burned (e.g.,
for electricity generation) and during metal smelting and
other industrial processes. High concentrations of SO2 are
associated with multiple health and environmental effects
(U.S. EPA, 2003). The highest concentrations of SO2 have
been recorded in the vicinity of large industrial facilities.
Although relatively few people live in areas where SO2
concentrations exceed the National Ambient Air Quality
Standards (NAAQS), SO2 emissions are an important
environmental issue because they are a major precursor to
ambient PM2 concentrations: many more people live in
PM2 5 non-attainment areas, which has several documented
human health and ecological effects (the PM Concentra-
tions indicator, p. 2-29).
2-34
EPA's 2008 Report on the Environment
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INDICATOI
Sulfur Dioxide Emissions (continued)
Health effects associated with SO depend on the expo-
sure concentrations and durations, and on the susceptibility
of exposed populations. Asthmatics are much more suscep-
tible to SO exposure than people who do not have asthma
(U.S. EPA, 1986). Effects associated with longer-term
exposures to high concentrations of SO2, in conjunction
•with high levels of PM, include respiratory illness, altera-
tions in the lungs' defenses, and aggravation of existing
heart or lung disease. The most susceptible populations
under these conditions include individuals with cardiovas-
cular disease or chronic lung disease, children, and older
adults (U.S. EPA, 1982).
Many other environmental concerns are associated with
high concentrations of SO2. For example, airborne SO2,
along with NO , contributes to acidic deposition (the Acid
Deposition indicator, p. 2-37); SO is a major precursor to
PM2 5 (the PM Concentrations indicator, p. 2-29); and SO2
contributes to impaired visibility (the Regional Haze indi-
cator, p. 2-33). SO2 exposure also can harm vegetation by
increasing foliar injury, decreasing plant growth and yield,
and decreasing the number and variety of plant species in a
given community. Finally, SO can accelerate the corro-
sion of materials (e.g., concrete, limestone) that are used
in buildings, statues, and monuments that are part of the
nation's cultural heritage (U.S. EPA, 1982).
This indicator presents SO emissions from tradition-
ally inventoried anthropogenic source categories: (1) "Fuel
combustion: selected power generators," which includes
emissions from coal-, gas-, and oil-fired power plants that
are required to use continuous emissions monitors (CEMs)
to report emissions as part of the Acid Rain Program
(ARP); (2) "Fuel combustion: other sources," which
includes industrial, commercial, and institutional sources,
as well as residential heaters and boilers not required to use
CEMs; (3) "Other industrial processes," which includes
chemical production and petroleum refining; (4) "On-
road vehicles," which includes cars, trucks, buses, and
motorcycles; (5) "Nonroad vehicles and engines," which
include farm and construction equipment, lawnmowers,
chainsaws, boats, ships, snowmobiles, aircraft, and others.
Because a substantial portion of airborne SO2 comes from
fossil fuel combustion in electric utilities, this indicator
includes the separate "Fuel combustion: selected power
generators" category in addition to the four categories
presented in the other emissions indicators.
SO emissions data are tracked by the National Emissions
Inventory (NEI). The NEI is a composite of data from
many different sources, including industry and numer-
ous state, tribal, and local agencies. Different data sources
use different data collection methods, and many of the
emissions data are based on estimates rather than actual
measurements. For major electricity generating units, most
data come from CEMs that measure actual emissions. For
Exhibit 2-27. SC>2 emissions in the U.S. by
source category, 1990 and 1996-20023
30
1 25
o
c 20
_o
1 15
w
I1D
1 5
0
Other industrial
processes
On-road and
nonroad
mobile
sources
Fuel combustion:
selected power generators'5
Fuel combustion: other sources
'90
'96
'97
'99
'00
'01
'02
Year
"Data are presented for 1990 and 1996-2002, as datasets from
these inventory years are fully up to date. Data are available for
inventory years 1991-1995, but these data have not been updated
to allow comparison with data from 1990 and 1996-2002.
bThis category includes emissions from only those power plants
required to use continuous emissions monitors under the Acid
Rain Program.
Data source: U.S. EPA, 2007b
other fuel combustion sources and industrial processes,
data are estimated using emission factors. Emissions from
on-road and nonroad sources were estimated using EPA-
approved modeling approaches (U.S. EPA, 2007a).
NEI data have been collected since 1990 and cover all
50 states and their counties, D.C., the U.S. territories of
Puerto Rico and Virgin Islands, and some of the territories
of federally recognized American Indian nations. Data are
presented only for 1990 and from 1996 to 2002; prior to
1996, only the 1990 data have been updated to be compa-
rable to the more recent inventories.
What the Data Show
National estimated SO emissions decreased 37 percent
between 1990 and 2002 (from 23,064,000 to 14,639,000
tons) (Exhibit 2-27). This downward trend resulted
primarily from emissions reductions at electric utili-
ties. Between 1990 and 2002, air emissions from electric
utilities have consistently accounted for roughly two-thirds
of the nation-wide SO emissions.
Net SO2 emissions declined in all EPA Regions between
1990 and 2002 (Exhibit 2-28). During this time frame, the
largest percent reductions in SO emissions were seen in
Regions 1 (59 percent), 2 (49 percent), and 5 (48 percent),
and the smallest reductions were observed in Regions 6 (15
percent) and 9 (18 percent).
EPA's 2008 Report on the Environment
2-35
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INDICATOR
Sulfur Dioxide Emissions (continued)
Indicator Limitations
• Though emissions from most electric utilities are mea-
sured directly using continuous monitoring devices,
SO2 emissions data for other source types are based on
estimates that employ emission factors generated from
empirical and engineering studies. Although these esti-
mates are generated using -well-established approaches,
the estimates have uncertainties inherent in the emission
factors and emissions models used to represent sources
for which emissions have not been directly measured.
• Comparable SO2 emissions estimates through the NEI
are available only for 1990 and 1996-2002. Data for
1991-1995 are not provided due to differences in emis-
sions estimation methodologies from other inventory
years, which could lead to improper trend assessments.
• SO2 emissions from "miscellaneous sources" are not
included in the total emissions. Details on emissions from
miscellaneous sources can be found by downloading 2002
NEI inventory data for the "nonpoint sector" (http://
www. epa.gov/ttn/chief/net/2002inventory.html).
• The methodology for estimating emissions is continually
reviewed and is subject to revision. Trend data prior to
these revisions must be considered in the context of
those changes.
• Not all states and local agencies provide the same data or
level of detail for a given year.
Data Sources
Summary data in this indicator were provided by EPA's
Office of Air Quality Planning and Standards, based on
SO2 emissions data in the NEI (U.S. EPA, 2007b)
(http: //www. epa.gov/ttn/chief/net/2002inventory.html).
This indicator aggregates the NEI data by source category
and EPA Region.
References
U.S. EPA (United States Environmental Protection
Agency). 2007a. Documentation for the final 2002 mobile
National Emissions Inventory, Version 3.
U.S. EPA. 2007b. Data from the 2002 National Emissions
Inventory, Version 3.0. Accessed 2007.
Exhibit 2-28. SC>2 emissions in the U.S. by EPA
Region, 1990 and 1996-20023
-R1
—R2
—R3
-R4
—R5
R6
R7
R8
-R9
-R10
'96 '97
Year
aData are presented for 1990
and 1996-2002, as datasets
from these inventory years are
fully up to date. Data are
available for inventory years
1991-1995, but these data have
not been updated to allow
comparison with data from
1990 and 1996-2002.
Data source: U.S. EPA, 2007b
'01 '02
EPA Regions
U.S. EPA. 2003. National air quality and emissions trends
report—2003 special studies edition. EPA/454/R-03/005.
Research Triangle Park, NC.
U.S. EPA. 1986. Second addendum to the air quality
criteria for particulate matter and sulfur oxides (1982):
Assessment of newly available health effects information.
EPA/450/S-86/012. Research Triangle Park, NC.
U.S. EPA. 1982. Air quality criteria for particulate matter
and sulfur oxides. EPA/600/P-82/020a-c. Research Tri-
angle Park, NC.
2-36
EPA's 2008 Report on the Environment
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INDICATOI
Acid Deposition
Every year, millions of tons of sulfur dioxide and nitro-
gen oxides are emitted to the atmosphere as a result of
the burning of fossil fuels and from other high temperature
sources (the Sulfur Dioxide Emissions indicator, p. 2-34;
the Nitrogen Oxides Emissions indicator, p. 2-16). These
gases react with water, oxygen, and oxidants to form acidic
compounds, which may be carried hundreds of miles by
the wind—even across state or national borders. Acid
deposition occurs when these compounds fall to the Earth
in one of two forms: wet (dissolved in rain, snow, and fog)
or dry (solid and gaseous particles deposited on surfaces
during periods of no precipitation). While wet deposi-
tion is the more widely recognized form (more commonly
referred to as "acid rain"), dry deposition can account for
20 to 80 percent of total acid deposition depending on
location and climate (MACTEC Engineering and Con-
sulting, Inc., 2005). In the environment, acid deposition
causes soils and water bodies to acidify, which can make
the water unsuitable for some fish and other wildlife. Some
types of ecosystems, those with less "buffering" capacity,
are more sensitive to acid deposition than others.
Scientists often use acid neutralizing capacity, a measure
of the amount of anions, protons, and non-proton cations
in the water, as an indicator of which lakes and streams are
most sensitive to acidification (NAPAP, 1991). Most surface
•waters in the West do not exhibit many symptoms of acidi-
fication, because relatively small amounts of acid deposition
occur in acid-sensitive regions. In the Northeast and along
the Appalachian Mountains, however, relatively high levels
of acid deposition occur in acid-sensitive regions, or regions
•without enough geochemical buffering capacity to prevent
acidification of surface waters by acid deposition (the Lake
and Stream Acidity indicator, p. 2-42). Therefore, reduc-
tions in acid deposition have the largest impact on acidifica-
tion of lakes and streams in those areas.
Acid deposition damages some trees, particularly at
high elevations, and speeds the decay of buildings, statues,
and sculptures that are part of our national heritage (U.S.
EPA, 2003). The nitrogen portion of acid deposition also
contributes to eutrophication in coastal ecosystems, the
symptoms of which include potentially toxic algal blooms,
fish kills, and loss of plant and animal diversity. Acidi-
fication of lakes and streams can increase the amount of
methylmercury available in aquatic systems (Winfrey and
Rudd, 1990). Finally, increased levels of sulfate in ground-
level air, a phenomenon related to dry deposition, can con-
tribute to decreased visibility as well as a variety of human
health problems (U.S. EPA, 2003).
Total acid deposition in this indicator is determined using
•wet deposition measurements and dry deposition calculated
from ambient air concentration measurements. Wet depo-
sition is measured through chemical analysis of rainwater
collected at sites across the U.S. The primary source of wet
Exhibit 2-29. Wet sulfate (SC>42") deposition in
the contiguous U.S., 1989-1991 and 2004-20063
A. Average wet S042 deposition, 1989-1991
B. Average wet S042 deposition, 2004-2006
"Coverage: 169
monitoring sites in
1989-1991 and 202
monitoring sites in
2004-2006.
Data source: NADP,
2007
Wet S042 deposition
(kilograms per hectare):
048 12 16 20 24 28 >32
•Monitoring site
deposition information comes from the National Atmo-
spheric Deposition Program/National Trends Net-work.
The chemical components of wet deposition include sulfate,
nitrate, and ammonium. Dry deposition is not measured
directly. EPA's Clean Air Status and Trends Net-work deter-
mines dry deposition inferentially by measuring ambient
air concentrations of acidic compounds and then calculat-
ing deposition rates using a multi-layer model that depends
on meteorological data collected at the sites as -well as local
vegetative conditions (http://-www.epa.gov/castnet/).
Chemicals measured include components of particulate
matter (sulfate [SO42~] and nitrate [NO3~]), gaseous nitric
acid (HNO3), sulfur dioxide (SO2), ammonia (NH3), and
ammonium (NH4+).
EPA's 2008 Report on the Environment
2-37
-------
INDICATOR
Deposition (continued)
This indicator uses the 3-year average from 1989-1991 as
a baseline, as this period immediately predates controls on
sulfur and nitrogen oxide emissions mandated by the 1990
Clean Air Act Amendments. Baseline data are compared to
the most recent 3-year average data available (2004-2006).
Use of 3-year average data helps ensure that trends reflect
actual changes in acid deposition, instead of shorter-term
fluctuations in meteorological conditions. Additionally,
this indicator presents annual trend data for total deposi-
tion, which characterizes deposition over the entire period
of record, not just for the baseline and most recent 3-year
average periods.
What the Data Show
Wet Deposition Trends
Analyses of long-term monitoring data from the National
Atmospheric Deposition Program show that wet deposition
of both sulfur and nitrogen compounds has decreased over
the last 17 years (Exhibits 2-29 and 2-30).
Wet sulfate deposition decreased across much of the U.S.
during the 1990s (Exhibit 2-29). The greatest reductions
in wet sulfate deposition occurred in the Mid-Appalachian
region (Maryland, New York, West Virginia, Virginia,
and most of Pennsylvania) and the Ohio River Valley. Less
dramatic reductions were observed across much of New
England and portions of the Southern Appalachians. Aver-
age regional decreases in wet deposition of sulfate between
the periods 1989-1991 (panel A) and 2004-2006 (panel B)
•were approximately 35 percent in the Northeast, 33 percent
in the Midwest, 28 percent in the Mid-Atlantic, and 20
percent in the Southeast.
Wet nitrate deposition decreased approximately 33
percent across the Northeast and 27 percent in the
Mid-Atlantic between the periods 1989-1991 (Exhibit
2-30, panel A) and 2004-2006 (panel B). However, there
is a high degree of variability in the measurements used to
calculate these percentages, complicating efforts to reliably
estimate trends for wet nitrate deposition. Wet deposition
of inorganic nitrogen has not changed substantially in the
rest of the country over this period.
Total Deposition Trends
As with wet deposition, total deposition (the sum of wet
and dry deposition) decreased between 1989-1991 and
2004-2006, and reductions were more substantial for
sulfur compounds than for nitrogen compounds (Exhibits
2-31 and 2-32). In the eastern U.S., where data are most
abundant, total sulfur deposition decreased by 36 percent
between 1990 and 2005 (Exhibit 2-33), while total nitro-
gen deposition decreased by 19 percent over the same time
frame (Exhibit 2-34). Note that total nitrogen deposition
in this indicator does not include nitrogen components,
such as ammonia, which can be a significant portion of the
dry deposition.
Exhibit 2-30. Wet nitrate (NOs) deposition in
the contiguous U.S., 1989-1991 and 2004-20063
A. Average wet N03 deposition, 1989-1991
B. Average wet N03 deposition, 2004-2006
"Coverage: 169
monitoring sites in
1989-1991 and 202
monitoring sites in
2004-2006.
Data source: NADP,
2007
Wet NOs' deposition
(kilograms per hectare):
02468 1012 14 16 18 20 22 >24
• Monitoring site
Indicator Limitations
• Geographic coverage is limited, particularly for dry depo-
sition (and thus total deposition as well), but the concentra-
tion of sites in the Midwest and Northeast is justified by
the fact that acid rain is much more of a problem in those
regions than it is in the West, Great Plains, or Southeast.
• Measurement techniques for dry deposition have improved
substantially, but characterization of dry deposition still
requires a combination of measurements and modeling,
which has inherent uncertainties. Further, dry deposition
presented in this indicator does not include contributions
from deposition of gaseous ammonia.
2-38
EPA's 2008 Report on the Environment
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INDICATOI
Acid Deposition (continued)
Exhibit 2-31. Total sulfur deposition in the contiguous U.S., 1989-1991 and 2004-20063
A. Average total sulfur deposition, 1989-1991
16.2
^rfcr^
3.2 J6-6. 20 2^193 W
16.4 198%14S
IBB_^
^^. 10K 11 n
B. Average total sulfur deposition, 2004-2006
Coverage: 37 monitoring sites in 1989-1991
and 73 monitoring sites in 2004-2006.
Data source: NADP, 2007; U.S. EPA, 2007
r10
-20
Numbers indicate total sulfur deposition (kilograms per hectare),
averaged over a 3-year period.
Sizes of circles indicate the relative magnitude of total sulfur deposition.
Colors in circles indicate the breakdown of total sulfur deposition:
• Dry sulfur deposition Wet sulfur deposition
EPA's 2008 Report on the Environment 2-39
-------
INDICATOI
Acid Deposition (continued)
Exhibit 2-32. Total nitrogen deposition in the contiguous U.S., 1989-1991 and 2004-20063
A. Average total nitrogen deposition, 1989-1991
Numbers indicate total nitrogen deposition (kilograms per hectare), averaged
15,
over a 3-year period.
f —zg-10 Sizes of circles indicate the relative magnitude of total nitrogen deposition.
Colors in circles indicate the breakdown of total nitrogen deposition:
Dry nitrogen deposition "Wet nitrogen deposition
B. Average total nitrogen deposition, 2004-2006
Numbers indicate total nitrogen deposition (kilograms per hectare), averaged
over a 3-year period.
_15 Sizes of circles indicate the relative magnitude of total nitrogen deposition.
—10
f5 Colors in circles indicate the breakdown of total nitrogen deposition:
Dry HN03deposition Dry N03~ deposition Wet N03~ deposition
•Dry NIV deposition BWet NIV deposition
3.6
"Coverage: 37 monitoring sites in 1989-1991 and 73 monitoring sites in 2004-2006.
Data source: NADP, 2007; U.S. EPA, 2007
2-40
EPA's 2008 Report on the Environment
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INDICATOI
Acid Deposition (continued)
Exhibit 2-33. Total sulfur deposition in the
eastern United States, 1990-2005a
90% of sites have annual sulfur deposition
below this line
10% of sites have annual
sulfur deposition below this line
'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05
Year
Coverage: 34 monitoring sites in the eastern United States.
Data source: MACTEC Engineering and Consulting, Inc., 2006
Exhibit 2-34. Total nitrogen deposition in the
eastern United States, 1990-2005a
12
90% of sitesjiave annual nitrogen deposition
below this line
If 2
10% of sites have annual nitrogen deposition
below this line
'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05
Year
Coverage: 34 monitoring sites in the eastern United States.
Data source: MACTEC Engineering and Consulting, Inc., 2006
Data Sources
Summary data in this indicator were provided by EPA's
Office of Atmospheric Programs, based on deposition
data from two sources. Wet deposition data are from the
National Atmospheric Deposition Program/National Trends
Network (NADP, 2007) (http://nadp.sws.umc.edu/), and
dry deposition data are from the Clean Air Status and
Trends Network (U.S. EPA, 2007) (http://www.epa.gov/
castnet). This indicator aggregates data across 3-year periods
to avoid influences from short-term fluctuations in meteoro-
logical conditions, and wet deposition data were interpolated
among monitoring stations to generate the maps shown in
Exhibits 2-29 and 2-30.
References
MACTEC Engineering and Consulting, Inc. 2006. Clean
Air Status and Trends Network (CASTNET): 2005 annual
report. Prepared for U.S. EPA, Office of Air and Radiation.
MACTEC Engineering and Consulting, Inc. 2005. Clean
Air Status and Trends Network (CASTNET): 2004 annual
report. Prepared for U.S. EPA, Office of Air and Radiation.
NADP (National Atmospheric Deposition Program). 2007.
Data from the NADP/National Trends Network.
Accessed 2007.
NAPAP (National Acid Precipitation Assessment Program).
1991. 1990 integrated assessment report. Washington, DC.
U.S. EPA (United States Environmental Protection
Agency). 2007. Data from the Clean Air Status and Trends
Network. Accessed 2007.
U.S. EPA. 2003. Latest findings on national air quality:
2002 status and trends. EPA/454/K-03/001. Research
Triangle Park, NC.
Winfrey, M.R., andJW.M. Rudd. 1990. Environmental
factors affecting the formation of methyl mercury in low
pH lakes. Environ. Toxicol. Chem. 9(7):853-869.
EPA's 2008 Report on the Environment
2-41
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INDICATOR
Lake and Stream Acidity
Acid deposition can have serious effects on aquatic
ecosystems. For example, aquatic organisms in acidi-
fied \vaters can develop calcium deficiencies that weaken
bones and exoskeletons and cause eggs to be weak or brittle.
Acidified waters can impair the ability offish gills to extract
oxygen from water and change the mobility of certain trace
metals (e.g., aluminum, cadmium, manganese, iron, arsenic,
mercury), which in turn can place fish and other species
sensitive to these metals at risk (NAPAP, 1991). The Acid
Deposition indicator (p. 2-37) explains the factors that con-
tribute to acid deposition and describes how acid deposition
patterns have changed over the last 17 years.
The susceptibility of a water body to acidification
depends on the ability of the water and -watershed soils to
neutralize the acid deposition it receives. The best mea-
sure of this ability is acid neutralizing capacity (ANC),
•which characterizes the amount of dissolved compounds
that \vill counteract acidity. Every body of water has a
measurable ANC, which depends largely on the surround-
ing -watershed's physical characteristics, such as geology,
soils, and size. The ANC of a body of-water reflects the
relative proportions of positive and negative ions entering
the -water from sources such as atmospheric inputs and the
soil and bedrock surrounding and underlying the -water
body. The higher the ANC, the more acid a -water body
can neutralize and the less susceptible it is to acidification.
As ANC approaches zero, the ability to neutralize acidity
decreases. Surface -water -with an ANC greater than 200
microequivalents per liter (jaeq/L) is usually considered
insensitive to acidification; surface -water -with an ANC less
than 50 (aeq/L is considered highly sensitive to acidifica-
tion (is often seasonally acidic); and surface water with an
ANC less than 0 (aeq/L is considered chronically acidic,
meaning the -watershed no longer has the capacity to neu-
tralize further acid deposition (U.S. EPA, 2003). ANC can
be negative -when anions exceed non-proton cations (i.e.,
•when there are free protons [H+ ions] in solution).
The National Acid Precipitation Assessment Program
identified several regions in the U.S. as containing many of
the surface -waters sensitive to acidification (Exhibit 2-35).
Where soil buffering capacity is poor, lakes and streams
may be vulnerable to acidification (NAPAP, 1991).
This indicator is derived from ANC measurements on
probability survey samples representing 8,664 lakes and
75,113 km of streams in the four geographic regions shown
in Exhibit 2-36. These measurements -were collected as
part of the Temporally Integrated Monitoring of Ecosys-
tems (TIME) project and on 78 additional acid-sensitive
lakes and 78 acid-sensitive streams in the Long-Term
Monitoring (LTM) project, for -which data -were available
between 1992 and 2005 (U.S. EPA, 2003, 2007). The lakes
sampled include only those in areas potentially sensitive
to acidification -with areas greater than 1 hectare. This
indicator focuses only on the northeastern U.S.; because
Exhibit 2-35. Areas with acid-sensitive waters
in the contiguous U.S.
West
New
England
Mid-Atlantic
Coastal Plain
Florida
Data source: NAPAP, 1991
monitoring is not ongoing for -western, Mid-western, and
southeastern -water bodies, trend data for those parts of the
country are not available.
What the Data Show
Between the early 1990s and 2005, ANC in lakes in the
Adirondack Mountains and in streams in the Northern
Appalachians (southern New York, -west-central Penn-
sylvania, and eastern West Virginia) increased to a degree
where many -water bodies that -were considered "chronically
acidic" in the early 1990s -were no longer classified as such in
2005 (Exhibit 2-36, panels A and C). Specifically, between
1991-1994 and 2005, the percent of chronically acidic water
bodies decreased in the Adirondack Mountains (from 13.0
percent to 6.2 percent) and in the Northern Appalachian
Plateau (from 11.8 percent to 8.0 percent). Additionally,
acid-sensitive lakes in New England are beginning to show
a decrease in acidity: the percent of chronically acidic lakes
in this region decreased from 5.6 percent in 1991-1994 to
4.3 percent in 2005 (panel B). This trend suggests that sur-
face -waters in these three regions are beginning to recover
from acidification, though acidic surface -waters are still
found in these regions.
The trend of increasing ANC in the Adirondack Moun-
tains, the Northern Appalachian Plateau, and New Eng-
land between the early 1990s and 2005 corresponds -with
a decrease in acid deposition in each of these regions (the
Acid Deposition indicator, p. 2-37) and reduced air emis-
sions of the main precursors to acid deposition, -which are
sulfur dioxide (the Sulfur Dioxide Emissions indicator, p.
2-34) and nitrogen oxides (the Nitrogen Oxides Emissions
indicator, p. 2-16).
ANC in the Ridge and Blue Ridge Region (east-central
Pennsylvania, -western Maryland, and -western Virginia)
2-42
EPA's 2008 Report on the Environment
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INDICATOI
Lake and Stream Acidity (continued)
has not risen from its 1987 level (Exhibit
2-36, panel D). Therefore, the number
of water bodies classified as "chronically
acidic" in this region remained essentially
unchanged between 1987 and 2005.
Indicator Limitations
• ANC sampling is limited to four regions,
all in the Northeast. (There is no long-
term coverage in the Southeast, West, or
Midwest.) These four regions were chosen
for sampling because previous research
has shown that they are among the most
sensitive to acid deposition due to the soils
and other -watershed characteristics. In
addition, as the Acid Deposition indica-
tor (p. 2-37) shows, many of these regions
receive the highest rates of acid deposition
in the U.S. For these reasons, the waters
sampled are likely to be at the greatest risk
of becoming acidified.
• Interpreting trends for this indicator is
complicated because multiple factors
contribute to changes in ANC levels. For
example, in areas where -watershed soil
characteristics are changing (e.g., decreases
in concentrations of base cations in the
soil), even dramatic reductions in acid
deposition -will not necessarily result in
large rebounds in ANC levels.
Data Sources
Summary data in this indicator -were
provided by EPA's Office of Atmospheric
Programs and are taken from a publica-
tion documenting how surface -waters have
responded to reduced air emissions of acid
rain precursors (U.S. EPA, 2003) and from
more recent unpublished results (U.S. EPA,
2007). Trends are based on data collected
in two net-works: the TIME project and the
LTM project. Because both net-works are
operated by numerous collaborators in state agencies, aca-
demic institutions, and other federal agencies, the monitor-
ing data are not available in a single publication or database.
The trend data in this indicator are based on observations
documented in several publications (see pages 15-17 of
U.S. EPA, 2003).
References
NAPAP (National Acid Precipitation Assessment Program).
1991. Acid deposition: State of science and technology,
volume II, aquatic processes and effects. Washington, DC.
Exhibit 2-36. Lake and stream acidity in selected acid-sensitive
regions in the U.S., 1987-2005
A.Adirondack Mountains
B. New England
* 15
10
C. Northern
Appalachian Plateau
"'
8.5
8.0
15
10
D. Ridge and Blue
Ridge Region
O
CD
Q-
5.0
5.0
5.0
1993-1994
2000
Year
2005
1987
2000
Year
2005
Data source: U.S. EPA, 1988, 2003,2007
U.S. EPA (United States Environmental Protection
Agency). 2007. Unpublished data from the Temporally
Integrated Monitoring of Ecosystems (TIME) net-work.
U.S. EPA. 2003. StoddardJ.L., J.S. Kahl, F.A. Devmey,
D.R. DeWalle, C.T Driscoll, A.T. Herlihy, J.H. Kellogg,
P.S. Murdoch, J.R. Webb, and K.E. Webster. Response of
surface -water chemistry to the Clean Air Act Amendments
of 1990. EPA/620/R-03/001. Research Triangle Park, NC.
U.S. EPA. 1988. Chemical characteristics of streams in the
mid-Atlantic and southeastern United States. Volume I:
Population descriptions and physico-chemical relationships.
EPA/600/3-88/021a. Washington, DC. ^
EPA's 2008 Report on the Environment
2-43
-------
INDICATOR
Percent of Days with Air Quality Index Values
Greater Than 100
The Air Quality Index (AQI) provides information
on pollutant concentrations of ground-level ozone,
particulate matter, carbon monoxide, sulfur dioxide, and
nitrogen dioxide. Formerly known as the Pollutant Stan-
dard Index, the nationally uniform AQI is used by state
and local agencies for reporting daily air quality and air
quality related health advisories to the public.
In 1999, the AQI was updated to reflect the latest sci-
ence on air pollution health effects and to make it more
appropriate for use in contemporary news media (U.S.
EPA, 2003a). It also serves as a basis for community-based
programs that encourage the public to take action to
reduce air pollution on days when levels are projected to
be of concern. The index has been adopted by many other
countries (e.g., Mexico, Singapore, Taiwan) to provide
the public with information on air quality.
The AQI is based on pollutant concentration data
measured by the State and Local Air Monitoring Stations
net-work and by other special purpose monitors. The AQI
is monitored in city groupings known as metropolitan
statistical areas (MSAs), which are defined by the Office
of Management and Budget. For most pollutants in the
index, the concentration is converted into index values
between 0 and 500, "normalized" so that an index value
of 100 represents the short-term, health-based standard
for that pollutant as established by EPA (U.S. EPA, 1999).
The higher the index value, the greater the level of air
pollution and health risk. An index value of 500 reflects a
risk of imminent and substantial endangerment of public
health. The level of the pollutant with the highest index
value is reported as the AQI level for that day. An AQI
value greater than 100 means that at least one criteria
pollutant has reached levels at which people in sensitive
groups may experience health effects. A complete descrip-
tion of how AQI values are calculated and what they
represent is documented in many publications (e.g., U.S.
EPA, 2003b).
This indicator is based on the percent of days across 93
large MSAs (500,000 people or more) during the year
that recorded an AQI greater than 100 at one or more
monitoring sites in the MSA. While the AQI indicator
is calculated from ambient concentration data for criteria
pollutants, this indicator's trends should not be expected
to mirror the trends in the other ambient concentration
indicators, due to the differing spatial coverage of moni-
toring stations across the various indicators.
The percent of days with AQI greater than 100 was
calculated in two steps. First, for each year, the total
number of days with AQI above 100 in each of the 93
MSAs was summed in order to get a national total. Then,
the national total was divided by the total number of days
in the annual sample (365 X 93, or 33,945 days) to obtain
Exhibit 2-37. Percent of days with Air Quality
Index (AQI) greater than 100 in selected U.S.
metropolitan areas, 1990-2006ab
A. AQI trend based on all criteria pollutants (1990-2006)°
1999 was the first year PM2.5
was included in the AQI 2004-2006:3-year
1990-1992:3-year ^ average = 2.8%
average = 4.5%
'90 '92 '94 '96 '98 '00 '02 '04 '06
Year
B. AQI trend based on ozone (1990-2006)
1990-1992: 3-year
average = 4.3%
2004-2006: 3-year
average = 1.9%
oo
'02 '04
'06
"- 7
Year
Coverage: 93 metropolitan
areas for AQI trend based on _ 8
all criteria pollutants, 90
metropolitan areas for AQI
trend based on ozone, and 89
metropolitan areas for AQI
trend based on PM2.5.
bFor each MSA, the percentage
of days with AQI greater than
100 was calculated by dividing
the number of days per year
with AQI greater than 100 by
365 total days. However,
because PM2.5 is not
monitored daily in some areas,
the actual percentage of days
with AQI greater than 100
might be higher than what is shown in
C. AQI trend based
on PM2.5 (1999-2006)"
2004-2006: 3-year
average = 1.1%
1999-2001:3-year
average = 2.1%
- 2
i 1
Q_
0
III
Ikl.
'00 '02 '04 '06
Year
Panels A and C.
=l_ead does not factor into the AQI calculation for all criteria pollutants.
dData for 1990-1998 are not shown because 1999 was the first year
that PM2.5 was included in the AQI.
Data source: U.S. EPA, 2007
2-44
EPA's 2008 Report on the Environment
-------
INDICATOI
Percent of Days with Air Quality Index Values
Greater Than 100 (continued)
the percentage of days with AQI above 100 in a year. Note
that this calculation will understate the actual percent-
age of days with AQI above 100 for pollutants that are not
measured daily (e.g., PM25).
Data are presented for 1990 through 2006. However,
because meteorology can strongly influence AQI values in
a given year, the change in AQI over time is evaluated by
comparing the 3-year average observation at the begin-
ning of the period of record (i.e., 1990-1992) to the 3-year
average at the end (i.e., 2004-2006). Comparing 3-year
averages reduces the potential for biases introduced by
years with unique meteorological conditions. The air qual-
ity data that go into the index consist of daily (24-hour)
measurements for PM1Q and PM2 5 and continuous (1-hour)
measurements for CO, NO2, ozone, and SO2. Lead mea-
surements do not factor into the AQI. Of the pollutants
considered, only four (CO, ozone, PM, and SO2) usually
exhibit AQI values greater than 100.
What the Data Show
AQI Based on All Criteria Pollutants (Except Lead)
The percent of days with AQI greater than 100 in 93
large MSAs based on all criteria pollutants (except lead)
decreased from 4.5 over the 1990-1992 time frame to
2.8 over the 2004-2006 time frame (Exhibit 2-37, panel
A). The AQI data based on all criteria pollutants are not
directly comparable over this time frame, because PM2 5
measurements started to factor into the index in 1999. For
this reason, the indicator also presents AQI trends based
strictly on ozone and PM2 5 measurements.
AQI Based on Ozone Only
For a nearly identical subset of MSAs, the percent of days
•with AQI values greater than 100 due to ozone levels alone
(based on the 1997 NAAQS) decreased from 4.3 over the
1990-1992 time frame to 1.9 over the 2004-2006 time
frame (Exhibit 2-37, panel B). Before PM2 5 became part of
the index in 1999, ozone typically accounted for more than
90 percent of the days with AQI greater than 100.
AQI Based on PM25 Only
In the 1999-2001 period, PM2 concentrations accounted
for 2.1 percent of days with AQI greater than 100. This
contribution decreased in subsequent years, falling to 1.1
percent for the 2004-2006 period.
AQI in the EPA Regions Based on All Criteria Pollutants
(Except Lead)
Trends in AQI based on all criteria pollutants (except lead)
between 1990 and 2006 varied across the ten EPA Regions
(Exhibit 2-38). For nine of the Regions, the percent of days
•with AQI greater than 100 in 2006 was lower than that in
1990, though substantial year-to-year variability occurred.
Exhibit 2-38. Percent of days with Air Quality
Index (AQI) greater than 100 in selected U.S.
metropolitan areas by EPA Region, 1990-2006at
15
10
0
'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06
Year
-R1
R2
R3
R4
-R5
R6
R7
R8
-R9
-R10
-Nat'l
Coverage: 93 metropolitan areas.
bTrend is based on AQI data for
all criteria pollutants, except for
lead. Note that 1999 was the
first year that PM2.5 was
included in the AQI.
Data source: U.S. EPA, 2007
EPA Regions
In Region 8, the percent of days with AQI greater than 100
in 2006 \vas higher than that observed in 1990. However,
as noted above, the AQI values for 1990 and 2006 are not
directly comparable, because PM2 5 measurements did not
factor into AQI prior to 1999.
Indicator Limitations
• The AQI does not address hazardous air pollutants.
• Air quality can vary across a single MSA. In assigning a
single number for each pollutant in each MSA, the AQI
does not reflect this potential variation.
• The data for this indicator are limited to MSAs compris-
ing urban and suburban areas with populations greater
than 500,000. Thus, this indicator does not reflect MSAs
smaller than 500,000 or rural areas.
• The AQI does not show which pollutants are causing
the days with an AQI of more than 100, or distinguish
between days with AQI slightly above 100 and days with
much higher AQI.
• This composite AQI indicator does not show which
specific MSAs, or how many MSAs, have problems—a
specific number of days could reflect a few areas with per-
sistent problems or many areas with occasional problems.
EPA's 2008 Report on the Environment
2-45
-------
INDICATOR
Percent of Days with Air Quality Index Values
Greater Than 100 (continued)
• This indicator only covers the days on which ambi-
ent monitoring occurred. Because PM2 is not sampled
daily in some areas, the data presented in this indicator
may understate the actual number of days on which AQI
values were greater than 100 due to PM25 concentrations.
Although ozone is not sampled throughout the year, the
percent of days with AQI greater than 100 is believed to
be accurate because monitoring occurs throughout the
summer, when ozone concentrations are highest.
Data Sources
Summary data in this indicator were provided by EPA's
Office of Air Quality Planning and Standards, based on
AQI values computed from ambient air monitoring data
for criteria pollutants found in EPA's Air Quality System
(U.S. EPA, 2007). Spreadsheets with the processed AQI
data for the 93 MSAs considered in this indicator are pub-
licly available (http://www.epa.gov/air/airtrends/factbook.
html). This indicator aggregates the processed AQI data
nationally and by EPA Region.
References
U.S. EPA (United States Environmental Protection
Agency). 2007. Data from the Air Quality System. Accessed
2007.
U.S. EPA. 2003a. National air quality and emissions trends
report—2003 special studies edition. EPA/454/R-03/005.
Research Triangle Park, NC.
U.S. EPA. 2003b. Air Quality Index: A guide to air quality
and your health. EPA-454/K-03-002.
U.S. EPA. 1999. Air quality index reporting, 40 CFR part 58.
INDICATOR
lercury Emissions
Iercury is an element that occurs naturally in the envi-
ronment. However, many industrial processes, such
as coal combustion, medical and hazardous waste incin-
eration, municipal waste combustion, gold mining, and
certain chemical manufacturing operations, have increased
the amount of mercury released to the air. What happens
to mercury after it is emitted depends on several factors:
the form of mercury emitted, the location of the emis-
sions sources, how high above the landscape the mercury
is released (e.g., the height of the stack), the surround-
ing terrain, and the weather. Depending on these factors,
atmospheric mercury can be transported over a range of
distances before it is deposited, potentially resulting in
deposition on a local, regional, continental, or global scale.
While some domestic anthropogenic mercury emissions
are deposited within the contiguous U.S., the majority
of such emissions combine with anthropogenic emissions
from other countries and natural emissions worldwide to
form a pool of mercury that circulates globally (Seigneur
etal, 2004; U.S. EPA, 1996).
Because it does not degrade in the environment, most
mercury emitted to the atmosphere eventually deposits
onto land or water bodies. Through a series of chemical
transformations and environmental transport processes,
airborne mercury that deposits to the Earth's surface can
eventually accumulate in the food web (the Lake Fish Tis-
sue indicator, p. 3-63), most profoundly in those species
near the top of the food web (e.g., shark, swordfish). The
Blood Mercury indicator (p. 5-12) describes the human
health effects associated with mercury exposure.
This indicator presents mercury emissions from the fol-
io-wing categories: (1) "Industrial processes: gold mining";
(2) "Industrial processes: hazardous waste incineration"; (3)
"Industrial processes: electric arc furnaces"; (4) "Industrial
processes: chlorine production"; (5) "Industrial processes:
medical waste incinerators"; (6) "Industrial processes:
municipal waste combustors"; (7) "Other industrial pro-
cesses," which includes chemical production and other
miscellaneous industrial processes; (8) "Fuel combustion:
industrial, commercial, and institutional boilers"; and (9)
"Fuel combustion: utility coal boilers." In order to better
characterize mercury emissions, this indicator presents
different source categories than other emissions indica-
tors in the Report on the Environment, including separate
categories for utility coal boilers and various industrial
processes that release mercury (e.g., medical waste incin-
eration, municipal waste combustion, hazardous waste
incineration, gold mining).
2-46
EPA's 2008 Report on the Environment
-------
INDICATOI
Mercury Emissions (continued)
250
200
150
100
50
Mercury emissions data are tracked by the
National Emissions Inventory (NEI). The
NEI is a composite of data from many differ-
ent sources, including industry and numerous
state, tribal, and local agencies. Different data
sources use different data collection methods,
and many of the emissions data are based on
estimates rather than actual measurements.
For most fuel combustion sources and indus-
trial processes, emissions are estimated using
emission factors.
NEI data have been collected since 1990
and cover all 50 states and their counties,
D.C., the U.S. territories of Puerto Rico and
Virgin Islands, and some of the territories
of federally recognized American Indian
nations. Data are presented for the baseline
period (1990-1993) and the latest year for
•which data are available (2002). The baseline
period represents a mix of years depending
on data availability for various source types.
While NEI data for air toxics (including
mercury) were also compiled for 1996 and
1999, the methodology used in those years
for air toxics differs considerably from the
methodology used in 1990-1993 and 2002
and therefore cannot be compared directly to
those data.
What the Data Show
Between 1990-1993 and 2002, annual nation-wide air
emissions of mercury decreased from 245 tons per year to
119 tons per year, a decrease of 52 percent (Exhibit 2-39).
The decline in mercury emissions is attributed primarily
to decreased emissions from medical waste incinerators and
municipal waste combustors. In 2002, coal-burning power
plants \vere the largest anthropogenic source of mercury
emissions to the air in the U.S., accounting for 42 percent
of all domestic anthropogenic mercury emissions.
Indicator Limitations
• The emissions data in this indicator are primarily based
on estimates, not direct measurements. Although these
estimates have inherent uncertainties, the data have been
generated using -well-established estimation methods.
• The trend shown is based on nation-wide aggregate data.
Regional and state trends may be different.
• Not all states and local agencies provide the same data or
level of detail for a given year.
Exhibit 2-39. Mercury emissions in the U.S. by source category,
1990-1993 and 2002
DGold mining
D Hazardous waste incineration
D Electric arc furnaces
D Chlorine production
D Medical waste incinerators
D Other industrial processes
FUB! combustion
D Industrial commercial and
institutional boilers
D Utility coal boilers
1990-1993
2002
Year
a1990-1993 is considered the baseline period for mercury emissions. The baseline period
spans multiple years due to the availability of emissions data for various source
categories. The data presented for the baseline period are annual emissions (tons per
year) and are therefore comparable to the 2002 data.
bMercury emissions from mobile sources are not depicted because they have been
estimated only for inventory year 2002 (0.8 tons) and not for the baseline period.
Data source: U.S. EPA, 2007
Data Sources
Summary data in this indicator -were provided by EPA's
Office of Air Quality Planning and Standards, based on
mercury emissions data in the NEI (U.S. EPA, 2007)
(http://www.epa.gov/ttn/chief/net/2002inventory.html).
This indicator aggregates the NEI data by source category.
References
Seigneur, C., K. Jayaraghavan, K. Lohman, P. Karamchan-
dani, and C. Scott. 2004. Global source attribution for mer-
cury deposition in the United States. Environ. Sci. Technol.
38:555-569.
U.S. EPA (United States Environmental Protection
Agency). 2007. Data from the 2002 National Emissions
Inventory, Version 3.0. Accessed 2007.
U.S. EPA. 1996. Mercury study report to Congress,
volumes I to VII. EPA/452/R-96/001b. Washington, DC.
EPA's 2008 Report on the Environment
2-47
-------
INDICATOI
Air Toxics Emissions
Toxic air pollutants, also known as air toxics or hazard-
ous air pollutants (HAPs), are those pollutants that
are known or suspected to cause cancer or are associated
•with other serious health (e.g., reproductive problems,
birth defects) or ecological effects. Examples of air tox-
ics include benzene, found in gasoline; perchloroethylene,
emitted from some dry cleaning facilities; and methylene
chloride, used as a solvent by a number of industries. Most
air toxics originate from anthropogenic sources, including
mobile sources (e.g., cars, trucks, construction equipment),
stationary sources (e.g., factories, refineries, power plants),
and indoor sources (e.g., building materials, cleaning
solvents). Some air toxics are also released from natural
sources such as volcanic eruptions and forest fires. Second-
ary formation of certain air toxics, such as acetaldehyde
and formaldehyde, can also occur when precursor chemi-
cals react in the atmosphere. The Clean Air Act identifies
188 air toxics associated with industrial sources. Twenty
of these air toxics also are associated with mobile sources
(U.S. EPA, 2003).
People who inhale certain air toxics at sufficient concen-
trations may experience various health effects, including
cancer, damage to the immune system, and neurological,
reproductive (e.g., reduced fertility), developmental, or
respiratory health problems (CDC, 2005). Air toxics also
can present risks through other exposure path-ways. For
example, air toxics may deposit onto soils or surface -waters,
where they can then enter the food web and may eventu-
ally be ingested by humans. Plants and animals also may be
harmed by exposures to air toxics (U.S. EPA, 2003).
Air toxics emissions data are tracked by the National
Emissions Inventory (NEI). The NEI is a composite of
data from many different sources, including industry and
numerous state, tribal, and local agencies. Different data
sources use different data collection methods, and many of
the emissions data are based on estimates rather than actual
measurements. For most fuel combustion sources and
industrial sources, emissions are estimated using emission
factors. Emissions from on-road and nonroad sources -were
estimated using EPA-approved modeling approaches (U.S.
EPA, 2007a).
NEI data have been collected since 1990 and cover all 50
states and their counties, D.C., the U.S. territories of Puerto
Rico and the Virgin Islands, and some of the territories of
federally recognized American Indian nations. The NEI
includes baseline air toxics data for the 1990-1993 period
and since then has been updated every 3 years. The baseline
period represents a mix of years depending on data availabil-
ity for various source types. While NEI data for air toxics
•were also compiled for 1996 and 1999, the methodology
used in those years for air toxics differed considerably from
the methodology that was used in 2002. Therefore, the 1996
and 1999 data are not presented because comparing the two
inventories might lead to invalid conclusions.
Exhibit 2-40. Air toxics emissions in the U.S. by
source category, 1990-1993 and 2002
« 7
CD
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CD 6
Q.
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I 4
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tf>
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LU
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dpi res (prescribed
burns and
wildtires)
D Nonroad vehicles
and engines
a On-road vehicles
D Stationary
sources (not
including fires)
1990-1993
2002
Year
a1990-1993 is considered the baseline period for air toxics
emissions. The baseline period spans multiple years due to the
availability of emissions data for various source categories. The
data presented for the baseline period are annual emissions (tons
per year) and are therefore comparable to the 2002 data.
Data source: U.S. EPA, 2007b
This indicator first presents emissions data for all air toxics
combined, both at the national level and broken down into
the ten EPA Regions. Consistent with the other emissions
indicators, the national data are organized into the following
source categories: (1) "Stationary sources," which include
fuel combustion sources (coal-, gas-, and oil-fired power
plants; industrial, commercial, and institutional sources;
as \vell as residential heaters and boilers) and industrial
processes (chemical production, petroleum refining, and
metals production) categories; (2) "Fires: prescribed burns
and \vildfires," for insights on contributions from some
natural sources; (3) "On-road vehicles," -which include cars,
trucks, buses, and motorcycles; and (4) "Nonroad vehicles
and engines," such as farm and construction equipment,
lawnmowers, chainsaws, boats, ships, snowmobiles, aircraft,
and others.
In addition to presenting emissions data aggregated across
all 188 air toxics, the indicator presents emissions trends for
five individual air toxics: acrolein, benzene, 1,3-butadiene,
ethylene dibromide, and hydrazine. These compounds
•were selected for display because EPA's 1999 National Air
Toxics Assessment estimates that they present the greatest
nation-wide health risks (-whether for cancer or non-cancer
endpoints) among the subset of air toxics for -which avail-
able emissions and toxicity data supported an evaluation
(U.S. EPA, 2006). This indicator breaks the emissions data
for these five air toxics into multiple source categories, -with
2-48
EPA's 2008 Report on the Environment
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INDICATOI
A i r Toxi cs E m i ss io ns (continued)
Exhibit 2-41. Air toxics emissions in the U.S. by
EPA Region, 2002
R1 R2 R3 R4 R5 R6 R7 R8 R9 R10
EPA Region
Data source: U.S. EPA, 2007b
EPA Regions
OD
the most appropriate categories for display purposes differ-
ing from one air toxic to the next.
What the Data Show
Trends Aggregated Across All 188 Air Toxics
According to NEI data, estimated annual emissions for the
188 air toxics combined decreased 36 percent, from 7.2
million tons per year in the baseline period (1990-1993)
to 4.6 million tons per year in 2002 (Exhibit 2-40). This
downward trend resulted primarily from reduced emis-
sions from stationary sources and on-road mobile sources.
In 2002, air toxics emissions in the ten EPA Regions
ranged from 166,000 tons in Region 1 to 1,056,000 tons
in Region 4 (Exhibit 2-41). Regional trends cannot be
characterized, because a complete set of state and local air
toxics emissions data are not available for the 1990-1993
baseline period.
Trends for Selected Air Toxics
Exhibit 2-42 shows emissions trends for five compounds
believed to account for the greatest health risks that are
attributed to air toxics, according to a recent modeling
study (U.S. EPA, 2006). The five plots in this exhibit show
how emissions trends vary from compound to compound.
Estimated emissions decreased between the baseline period
(1990-1993) and 2002 for all five selected air toxics: acro-
lein (51 percent decrease; see panel A), benzene (17 percent;
panel B), 1,3-butadiene (38 percent; panel C), ethylene
dibromide (63 percent; panel D), and hydrazine (84 percent;
panel E).
Indicator Limitations
• The emissions data are largely based on estimates.
Although these estimates are generated using -well-
established approaches, the estimates have inherent
uncertainties. The methodology for estimating emissions
is continually reviewed and is subject to revision. Trend
data prior to any revisions must be considered in the
context of those changes.
• The indicator is an aggregate number that represents
contributions from 188 different chemicals with widely
varying toxicities and human exposures. Therefore,
the nation-wide trend for total air toxics and the result-
ing health effects likely differs from emissions trends for
specific chemicals. Similarly, because the indicator is a
nation-wide aggregate statistic, the trend may not reflect
emissions trends for specific locations.
• Not all states and local agencies provide the same data or
level of detail for a given year.
• There is uncertainty associated -with identifying -which
air toxics account for the greatest health risk nation-wide.
Toxicity information is not available for every compound,
and emissions and exposure estimates used to character-
ize risk have inherent uncertainties. Additional limitations
associated -with the National Air Toxics Assessment are
well documented (U.S. EPA, 2006).
Data Sources
Summary data in this indicator -were provided by EPA's
Office of Air Quality Planning and Standards, based on
air toxics emissions data in the NEI (U.S. EPA, 2007b)
(http://www.epa.gov/ttn/chief/net/2002inventory.html).
This indicator aggregates the NEI data by source category,
EPA Region, and selected air toxics.
References
CDC (Centers for Disease Control and Prevention).
2005. Third national report on human exposure to
environmental chemicals. NCEH Pub. No. 05-0570.
Accessed September 9, 2005.
U.S. EPA (United States Environmental Protection
Agency). 2007a. Documentation for the final 2002 mobile
National Emissions Inventory, Version 3.
EPA's 2008 Report on the Environment
2-49
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INDICATOI
A i r Toxi cs E m i ss io ns (continued)
Exhibit 2-42. Emissions of selected air toxics in the U.S. by source category, 1990-1993 and 2002a
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A. Acrolein emissions
n Other sources
a Nonroad vehicles
and engines
nOn-road vehicles
n Structural fires
D Prescribed burns
and wildfires
1990-1993° 2002
Year
C. 1,3-Butadiene emissions
n Nonroad vehicles
and engines
n Prescribed burns
and wildfires
1990-1993'
2002
Year
E. Hydrazine emissions
n Miscellaneous organic
chemical manufacturing
• Other sources
n Industrial organic
chemical production
• Industrial inorganic
chemical production
1990-1993
2002
Year
B. Benzene emissions
.-. 600
cc
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3
o
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•I 100
.22
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n Residential wood
combustion
n Oil and natural gas
production
n Other sources
n Prescribed burns
and wildfires
n Nonroad vehicles
and engines
nOn-road vehicles
1990-1993 2002
Year
D. Ethylene dibromide emissions
70
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CD
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manufacturing
n Industrial organic
chemical production
n Other sources
1990-1993'
2002
Year
aThese five air toxics were selected for presentation because they
are estimated to present the greatest overall health risks
nationwide for cancer and non-cancer endpoints.
b1990-1993 is considered the baseline period for air toxics
emissions. The baseline period spans multiple years due to the
availability of emissions data for various source categories. The
data presented for the baseline period are annual emissions (tons
per year) and are therefore comparable to the 2002 data.
Data source: U.S. EPA, 2007b
U.S. EPA. 2007b. Data from the 2002 National Emissions
Inventory, Version 3.0. Accessed 2007.
U.S. EPA. 2006. 1999 national-scale air toxics assessment.
February.
U.S. EPA. 2003. National air quality and emissions trends
report—2003 special studies edition. EPA/454/R-03/005.
Research Triangle Park, NC.
2-50
EPA's 2008 Report on the Environment
-------
Ambient Concentrations of Benzene
Benzene is an air toxic emitted from gasoline service
stations, motor vehicle exhaust and fuel evaporation,
the burning of coal and oil, and various other sources. In
addition to being a common air pollutant, benzene may
also contaminate water. Urban areas generally have higher
ambient air concentrations of benzene than other areas.
People exposed to benzene at sufficient concentrations
may experience various health effects, including cancer
and damage to the immune system, as well as neurological,
reproductive (e.g., reduced fertility), developmental, respi-
ratory, and other health problems. Plants and animals may
also be harmed by exposures to benzene (U.S. EPA, 2003).
Benzene is the most widely monitored air toxic. Data
from the National Air Toxics Trends Sites net-work is
expected to provide trends information for other air toxics
in the next Report on the Environment.
This indicator reflects ambient concentrations in micro-
grams per cubic meter (jag/m3) of benzene from 1994 to
2006, based on the annual average. This indicator displays
trends averaged over 23 urban monitoring sites that have
consistent data for the period of record from Photochemi-
cal Assessment Monitoring Stations, Urban Air Toxics
Monitoring Stations, and Non-Methane Organic Com-
pound Monitoring Stations.
What the Data Show
Benzene concentrations declined 55 percent from 1994 to
2006 (Exhibit 2-43).
Also shown in Exhibit 2-43 are the 90th and 10th percen-
tiles based on the distributions of annual average concen-
trations at the 23 monitoring sites. These data provide
additional graphical representation of the distribution of
measured concentrations across the monitoring sites for
a given year: the shaded area in the exhibit displays the
concentration range where 80 percent of measured values
occurred for each year.
Indicator Limitations
• Benzene data represent only 23 urban sites in the U.S.
• Because of the limited number of sites that are primar-
ily located in urban areas, Exhibit 2-43 does not neces-
sarily represent an overall national trend in benzene
concentrations.
• Benzene, while an important air toxic, is only one of
many toxics typically found in outdoor air.
Exhibit 2-43. Ambient benzene concentrations
in the U.S., 1994-20063
- 4'5
,4.0
.
3.5
3.0
2.5
2.0
1.5
1.0
0.5
o.o
'94
90% of sites have concentrations
below this line
10% of sites have
concentrations below this line
'95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06
Year
Coverage: 23 monitoring sites nationwide (out of a total of 230
sites measuring benzene in 2006) that have sufficient data to
assess benzene trends since 1994.
Data source: U.S. EPA, 2007
Data Sources
Summary data in this indicator were provided by EPA's
Office of Air Quality Planning and Standards, based on
benzene ambient air monitoring data in EPA's Air Quality
System (U.S. EPA, 2007) (http://www.epa.gov/ttn/airs/
airsaqs/). National trends in this indicator are based on the
subset of benzene monitoring stations that have sufficient
data to assess trends since 1994.
References
U.S. EPA (United States Environmental Protection
Agency). 2007. Data from the Air Quality System.
Accessed 2007.
U.S. EPA. 2003. National air quality and emissions trends
report—2003 special studies edition. EPA/454/R-03/005.
Research Triangle Park, NC.
EPA's 2008 Report on the Environment
2-51
-------
INDICATOR
Concentrations of Ozone-Depleting Substances
Ozone, a gas present throughout the Earth's atmosphere,
is a pollutant at the Earth's surface but forms a protec-
tive layer in the stratosphere, helping shield the Earth from
the sun's ultraviolet (UV) radiation. Exposure to UV rays
is associated with skin cancer, cataracts, and other human
health and ecological problems (U.S. EPA, 2006).
Starting in the late 1970s, stratospheric ozone levels were
observed to be declining due to worldwide releases of
various human-produced chemicals referred to as ozone-
depleting substances (ODSs), particularly halocarbons such
as the long-lived chlorofluorocarbons (CFCs), bromine-
containing halons, and methyl bromide. Through rapid cat-
alytic reactions with ozone, the chlorine and bromine from
these chemicals have depleted the protective ozone layer (the
Ozone Levels over North America indicator, p. 2-54).
World-wide production and consumption of ODSs is
being progressively eliminated under the provisions of the
1987 Montreal Protocol on Substances That Deplete the
Ozone Layer. Over time, reducing the atmospheric loading
of ODSs is expected to result in global increases in strato-
spheric ozone. However, because some ODS gases have
long atmospheric lifetimes, and because of pre-phaseout
ODS stockpiling for post-phaseout use, ambient concen-
trations of ODSs have only recently begun to stabilize and
in some cases begun to decline. While some gases, like
methyl chloroform, decay quickly in the atmosphere, other
gases, like CFCs and halons, have atmospheric lifetimes on
the order of hundreds or thousands of years.
Measures of effective equivalent troposphere chlorine
(EEC1) and effective equivalent stratospheric chlorine
(EESC) are commonly used to represent atmospheric con-
centrations of ODSs. Both represent ODS concentrations
•weighted by their potential to catalyze the destruction of
stratospheric ozone relative to the ability of chlorine to do
so. (EESC is typically derived by adding a 3-year time lag to
EEC1 to account for the time it takes for emissions of ODSs
at the Earth's surface to migrate from the troposphere to the
stratosphere and cause stratospheric ozone depletion.)
This indicator presents trends in concentrations of
tropospheric ODSs as EEC1. The EEC1 trend is based on
measurements from the National Oceanic and Atmo-
spheric Association (NOAA) Climate Monitoring and
Diagnostics Laboratory and estimates of halocarbon emis-
sions from industrial and international sources from 1995
to 2006. Concentrations of EEC1 are presented as -weighted
averages based on ground-based measurements of mixing
ratios5 since 1995 at the following remote locations: Alert,
North-west Territories, Canada; Barrow, Alaska; Niwot
Ridge, Colorado; Mauna Loa, Hawaii; American Samoa;
Cape Grim, Tasmania, Australia; and the South Pole
(NOAA CMDL, 2003). Data on total EEC1 are also avail-
able for 1992 through 1994, but these years of monitoring
Exhibit 2-44. Global effective equivalent chlorine
concentrations, 1995-20063
2,800
111 2,700
° '£
£ g. 2,600
1 1 2,500
§• =
CD O
g IB 2,400
'95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06
Year
Effective equivalent chlorine (EECI) is typically used to represent
atmospheric concentrations of ozone-depleting substances. The
EECI reflects contributions from multiple ozone-depleting
substances, weighted by their potential to catalyze the destruction
of stratospheric ozone.
Data source: NOAA, 2007
The mixing ratio
atmospheric pressure
is the ratio of the partial pressure of a gas to the total
nrp
are only presented in the chemical-specific graphs because
the monitoring did not include methyl bromide, a quan-
titatively important ODS. Because most ODSs have long
atmospheric half-lives, the ODS concentrations shown in
this indicator reflect past and recent contributions from
emissions sources -within the U.S. and -world-wide.
What the Data Show
Total EECI resulting from ODS emissions reached its
peak concentration in the mid-1990s at slightly over 2,700
parts per trillion of air by volume and has slowly declined
by approximately 12 percent since then (Exhibit 2-44).
Although tropospheric concentrations of CFCs and several
other individual ODS compounds have begun to decline,
concentrations of halons and selected hydrochlorofluoro-
carbons (HCFCs) have not yet stabilized.
Declines in EECI abundances of several ODSs in the
troposphere between 1992 and 2006 have contributed to
the decline in total EECI (Exhibit 2-45). EECI attributed
to methyl chloroform has decreased by nearly 90 percent
over this period due to decreased emissions as -well as its
short atmospheric lifetime. EECI associated -with CFCs has
decreased more slowly: 2006 levels are approximately 5
percent lower than the peak tropospheric concentration that
occurred between 1995 and 1997. The slow decay of CFCs
is a result of continued emissions of CFCs from stockpiles in
developed countries, continued use in developing countries,
and their longer atmospheric lifetimes. EECI from methyl
bromide has decreased nearly 20 percent from its peak in
2-52
EPA's 2008 Report on the Environment
-------
INDICATOI
Concentrations of Ozone-Depleting Substances (continued)
1998; however, continued use of methyl bromide in devel-
oping countries and in developed countries through critical
use exemptions slows the decrease in EEC1 associated with
this compound. EEC1 from methyl bromide exhibits sea-
sonal variations, which likely results from the seasonal use of
this chemical as a soil fumigant.
Although some tropospheric ODSs have declined in con-
centration, others, including halons and HCFCs, continue to
increase (Exhibit 2-45). EEC1 estimated from halon emissions
has increased by more than 50 percent from 1992 to 2006,
and EEC1 attributed to HCFCs in 2006 is more than 2.5
times higher than that from 1992. These trends reflect con-
tinued emissions of these ODSs from stockpiles in developed
countries and continued production and consumption in
developing countries (and developed countries for HCFCs),
as well as the longer atmospheric lifetimes of halons.
Indicator Limitations
• The calculation of EEC1 depends on the understanding
of the interactions and atmospheric residence times of
many different gases; incorrect knowledge about these
factors could affect trends in the EEC1.
• EEC1 is calculated by -weighting each ODS's concentra-
tion by the substance's ability to catalyze destruction of
stratospheric ozone, or the ozone destruction potential.
The ozone destruction potentials used to transform the
data have inherent uncertainties, which can affect the
trend analyses.
• Factors additional to trends in halocarbons affect trends
in stratospheric ozone. These factors include changes in
climate (e.g., temperature, winds), changes in emissions
and concentrations of trace gases like nitrous oxide and
methane, and changes in aerosol loading such as occurs
after an explosive volcanic eruption.
Data Sources
Tropospheric concentrations of ODSs presented in this
indicator are based on measurements made by NOAA's
Global Monitoring Division and summarized at an online
data repository (NOAA, 2007) (ftp://ftp.cmdl.noaa.gov/
hats/Total_Cl_Br/). The trend in this indicator was devel-
oped from a 2007 data file available from the repository,
•which updates tropospheric ODS concentrations previously
reported in the peer-reviewed literature (Montzka et al.,
1999, 2003).
References
Montzka, S.A., J.H. Butler, B.D. Hall, DJ. Mondeel, and
J.W. Elkins. 2003. A decline in tropospheric organic bro-
mine. Geophys. Res. Lett. 30(15):1826.
Exhibit 2-45. Global effective equivalent chlorine
concentrations of selected ozone-depleting
substances, 1992-20063
1,400
£ J 1,200
Is 1-°°°
, . Q.
g-| 600
£'«
••5 = 400
CD 02
^ § 200
CFCsb
'92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06
Year
"Effective equivalent chlorine (EECI) is typically used to represent
atmospheric concentrations of ozone-depleting substances. The EECI
of ozone-depleting substances is calculated from the substances'
atmospheric concentrations and their potential to catalyze the
destruction of stratospheric ozone.
bThe chlorofluorocarbons (CFCs) considered in this figure are CFC-11,
CFC-12, andCFC-113.
cThe halons considered in this figure are halon 1211 and halon 1301.
dThe hydrochlorofluorocarbons (HCFCs) considered in this figure are
HCFC-22, HCFC-141b, and HCFC-142b.
Data source: NOAA, 2007
Montzka, S.A., J.H. Butler, J.W. Elkins, T.M. Thompson,
A.D. Clarke, and L.T Lock. 1999. Present and future trends
in the atmospheric burden of ozone-depleting halogens.
Nature 398(6729):690-694.
NOAA (National Oceanic and Atmospheric Administra-
tion). 2007. Online repository of global tropospheric mixing
ratios of ozone-depleting gases. Accessed 2006.
NOAA CMDL (National Oceanic and Atmospheric
Administration, Climate Monitoring and Diagnostics
Laboratory). 2003. Summary report no. 27. Boulder, CO.
U.S. EPA (United States Environmental Protection
Agency). 2006. Air quality criteria for ozone and related
photochemical oxidants. EPA/600/R-05/004aF-cF.
Research Triangle Park, NC.
EPA's 2008 Report on the Environment
2-53
-------
INDICATOI
Ozone Levels over North America
Ozone is a gas present throughout the Earth's atmo-
sphere; 90 percent resides in the stratosphere, the layer
of the atmosphere that starts about 6 to 9 miles above the
Earth's surface at mid-latitudes, and the rest is located in
the troposphere, the atmospheric layer that lies between
the stratosphere and the Earth's surface. The environmen-
tal and human health implications of ground-level ozone
are very different from those of ozone higher in the atmo-
sphere, leading to the maxim: "Good up high, bad nearby"
(U.S. EPA, 2003). In the troposphere, ozone poses both
health and ecological risks, but the natural layer of ozone
in the stratosphere shields and protects the Earth's sur-
face from the sun's harmful ultraviolet (UV) rays, which
can lead to more cases of skin cancer, cataracts, and other
health problems (U.S. EPA, 2006).
Increases in surface UV radiation have been associ-
ated with reductions in total column ozone levels based
on spectral measurements at a number of sites in Europe,
North America, South America, Antarctica, and New
Zealand (Kerr and McElroy, 1993; Booth and Madronich,
1994; WMO et al., 2007). For example, measurements
between 1989 and 1993 over Toronto indicated that for
every 1 percent decrease in total column ozone, after
accounting for seasonal and daily variables not related to
ozone, there was a corresponding increase—between 1.1
percent and 1.3 percent—in erythemally active UV-B
radiation (Kerr and McElroy, 1993).
Ozone in the stratosphere is constantly being produced
naturally from dissociation of oxygen molecules by highly
energetic UV solar radiation. While this ozone is being
transported poleward and downward through the natural
motions of air in the stratosphere, it also is being naturally
destroyed through catalytic reactions involving primarily
nitrogen and hydrogen oxides.
Releases of various human-produced chemicals, such as
the long-lived chlorofluorocarbons, bromine-containing
halons, and methyl bromide (the Concentrations of Ozone-
Depleting Substances indicator, p. 2-52), have depleted the
levels of protective stratospheric ozone starting in the late
1970s, particularly at medium to high latitudes. The U.S.
has been a major contributor to the global emissions of these
halocarbons, accounting for about a quarter of total -world-
wide emissions before the major ozone-depleting substances
(ODSs) were banned in the 1990s. It takes about 3 years for
emissions of ODSs at the Earth's surface to migrate to the
stratosphere and cause stratospheric ozone depletion (WMO
et al., 2007).
This indicator tracks trends in the deviation from
pre-1980 levels in total annually averaged ozone values
integrated over the 35 to 60 degrees north latitude belt
(the latitudes roughly corresponding to North America)
from 1964 to 2006. The estimates are based on data from
several different sources including ground-based and satellite
Exhibit 2-46. Total ozone levels over North
America, 1964-2006ab
Is
•5
Ground-based data
Merged satellite data
GOME satellite data
SBUV-SBUV/2 satellite data
NIWA assimilated satellite
data
00 '05
aTotal ozone refers to the total ozone concentration in a column of air
between the Earth's surface and the top of the atmosphere.
bTrend data are representative of latitudes ranging from 35 degrees
north to 60 degrees north.
Data source: WMO et al., 2007
measurements. The data on total ozone from ground-based
measurements are from a net-work of surface stations, -which
are equipped -with spectrophotometers. These instruments
measure how thick the ozone layer -would be if compressed
in the Earth's atmosphere (at sea level and at 0°C), where
one Dobson Unit (DU) is defined to be 0.01 mm thickness
at standard temperature and pressure. Reliable data from
regular measurements at these ground-based stations are
available extending back to the 1960s, although geographi-
cal coverage is limited before the 1970s (Fioletov et al.,
2002; WMO et al., 2007).
Near-continuous global total ozone data are available
from satellite measurements beginning in 1979. These sat-
ellite data come from four sources: (1) The Global Ozone
Monitoring Experiment (GOME) refers to data collected
from instruments on board the European Space Agency's
ERS-2 satellite, for -which validated data are available
dating back to 1996; (2) The Solar Backscatter Ultravio-
let (SBUV) instruments have been collecting data since
1979, -with one instrument (SBUV) on board the Nimbus
7 satellite and the other instruments (SBUV/2) on board
a sequence of NOAA satellites; (3) The "merged satellite
data" refer to total ozone data dating back to 1970 (not
all years inclusive) constructed by merging observations
from the SBUV/2 data and data collected by Total Ozone
Mapping Spectrometer (TOMS) instruments on board the
Nimbus 7 satellite; and (4) The National Institute of Water
and Atmospheric Research (NIWA) assimilated data set
2-54
EPA's 2008 Report on the Environment
-------
Ozone Levels over North America (continued)
is a merged data set constructed from observations dating
back to 1979 collected by the TOMS, GOME, and SBUV
instruments. Other publications provide further documen-
tation on the four satellite data sets used in this indicator
(WMO etal, 2007).
What the Data Show
There was little ozone change (beyond natural variations
such as those resulting from the 11-year solar sunspot cycle)
before the late 1970s, but decreases in stratospheric ozone
began to occur after 1979 (Exhibit 2-46). The ground-based
data and four satellite data sets have similar ozone variations,
•with differences typically less than 0.5 percent. The mid-
latitude decline of approximately 6 percent between 1979
and 1995 is in general agreement with previous profile trend
estimates from satellite and ground-based records.
However, total ozone levels have begun to recover since
1995. For the mid-latitudes of the Northern Hemisphere,
the average of the total ozone levels for the 4-year period
from 2002 to 2005 is about 3 percent lower than the
pre-1980 levels in the Northern Hemisphere (WMO et
al., 2007). While this indicator covers the entire 35 to 60
degrees north latitude belt, ozone varies little by longitude
and the estimated 3 percent change in total ozone levels
can be taken to apply to North America.
This 3 percent change over North America is very similar
to the statistically significant globally averaged 3.5 decrease
in total ozone between pre-1980 levels and 2002-2005
(WMO et al., 2007). The decrease in the mid-latitudes of
the Southern Hemisphere, by contrast, has been nearly twice
as high as observed in the Northern Hemisphere, due largely
to the springtime "ozone hole" over Antarctica. The trends
in this indicator are consistent with well understood seasonal
variations in ozone, and with natural variations such as those
due to the 11-year solar cycle and the effects of volcanic
eruptions, suggesting that the long-term trends are those
resulting from the emissions of ODSs.
Indicator Limitations
• Fioletov et al. (2002) used estimates of ozone changes
from several different, independent sources to derive
some data used for this indicator. Differences in the cali-
bration of instruments used to obtain the ground-based
and satellite datasets together with interruptions in the
observational records produce datasets with measure-
ment errors typically around a few percent (WMO et al.,
2007). The figure presented does, however, show good
overall agreement among the different data sources for
changes in total ozone.
Data Sources
Summary data for this indicator were provided by the
World Meteorological Organization. The 1964-2006 data
in this indicator are taken from the Organization's 2006
Scientific Assessment of Ozone Depletion (WMO et al.,
2007), which presents ozone data based on multiple sets of
measurements (e.g., Fioletov et al., 2002).
References
Booth, R.C., and S. Madronich. 1994. Radiation ampli-
fication factors—improved formulation accounts for large
increases in ultraviolet radiation associated with Antarctic
ozone depletion. In: Weiler, C.S., and P.A. Penhale, eds.
Ultraviolet radiation and biological research in Antarctica.
Antarctic Research Series. Washington, DC: American
Geophysical Union, pp. 39-42.
Fioletov, V.E., G.E. Bodeker, J.B. Kerr, AJ. Miller, R.D.
McPeters, and R. Stolarski. 2002. The global ozone and
zonal total ozone variations estimated from ground-based
and satellite measurements: 1978-2000. J. Geophys. Res.
107(D22).
Kerr, J.B., and C.T McElroy. 1993. Evidence for large
upward trends of ultraviolet-B radiation linked to ozone
depletion. Science 262:1032-1034.
U.S. EPA (United States Environmental Protection
Agency). 2006. Air quality criteria for ozone and related
photochemical oxidants. EPA/600/R-05/004aF-cF.
Research Triangle Park, NC.
U.S. EPA. 2003. Ozone: good up high, bad nearby.
EPA/451/K-03/001. Washington, DC.
WMO (World Meteorological Organization), et al. 2007.
Scientific assessment of ozone depletion: 2006. Geneva,
Switzerland,
EPA's 2008 Report on the Environment
2-55
-------
INDICATO
Ozone and Particulate Matter Concentrations for
U.S. Counties in the U.S./Mexico Border Region
The border between the U.S. and Mexico spans approxi-
mately 2,000 miles, from the Pacific Ocean to the
Gulf of Mexico. The area is subjected to a unique blend
of increased industrial development (especially on the
Mexican side of the border), intense pressures because of
the shifting and growing population related to this devel-
opment, and an arid climate that can exacerbate many air
quality problems. Ozone and particulate matter are air
pollutants of particular concern. Rapid population growth
in urban areas of the (U.S./Mexico) border has resulted
in unplanned development, greater demand for land and
energy, traffic congestion, increased waste generation,
overburdened or unavailable waste treatment and disposal
facilities, increased frequency of chemical emergencies, and
an adverse impact on air quality (U.S. EPA, 2003).
Ground-level ozone is harmful to both human health
and the environment (the Ozone Concentrations indicator,
p. 2-22). Although some industrial sources release ozone
directly into the environment, most ground-level ozone
forms from chemical reactions involving nitrogen oxides,
volatile organic compounds, and sunlight. Ozone levels are
typically highest during the afternoon hours of the summer
months, when the influence of direct sunlight is the great-
est (U.S. EPA, 2006).
Exhibit 2-47. Ambient ozone, PM-io, and PM2 5 concentrations in U.S. counties in the US/Mexico border
area, 1986-2006a
55 E ""
-c -^ —
^0.12
Q.
Q_
£2 0.10
0.08
•o
c
_CD
S 0.06
"§ 0.04
I
o 0.02
CD
CD
" 0.00
A. Ozone concentrations
(1986-2006)
B. PM10 concentrations
(1988-2006)°
C. PM2.5 concentrations
(1999-2006)
'I 150
§ 1 125
o -=
CD ^>
J —100
e 8
25
_N_AAQS=J50ijg/mf
9-'91 '92-'94 '95-'97 '98-'00 '01-'03 '04-'06
Averaging period
0
'88-'90 '92-'94
'96-'98 '00-'02 '04-'06 '99-'01 '01-'03 '03-'05
Averaging period Averaging period
Counties with ambient air monitoring sites included in this indicator
Region 6
border
counties
— Region 9
border
counties
—National
average
Coverage: 29 ozone monitoring sites,
32 PM-io monitoring sites, and 14
PM2.5 monitoring sites located in U.S.
counties along the U.S./Mexico
border that have sufficient data to
assess trends over the time frames in
which these pollutants were
monitored.
b The figure displays the 1997 NAAQS
(0.08 ppm). Future versions of the
ROE will compare ozone
concentrations to the recently
promulgated 2008 NAAQS (0.075
ppm) or to the NAAQS in effect at
the time.
"National PM-|0 data are not depicted
because the approach used to track
PM-io concentrations in the U.S./Mexico border region
differs from that used on the national scale.
Data source: U.S. EPA, 2007
2-56
EPA's 2008 Report on the Environment
-------
Ozone and Particulate Matter Concentrations for
U.S. Counties in the U.S./Mexico Border Region (continued)
"Particulate matter" (PM) is the general term used for a
mixture of solid particles and liquid droplets found in the
air. Primary PM is released directly from emissions sources
into the atmosphere, while secondary PM is formed in
the air from reactions involving precursor chemicals (e.g.,
nitrogen oxides, sulfur dioxide, particle-producing organic
gases). Ambient air monitoring stations measure air concen-
trations of two size ranges of particles: PM2 5 (fine par-
ticles with aerodynamic diameter less than or equal to 2.5
micrometers [(am]) and PM1Q (particles with aerodynamic
diameters less than or equal to 10 (am, including PM2 5).
Exposure to coarse particles (i.e., particles with aerodynamic
diameters between 2.5 and 10 (am) can aggravate respiratory
conditions such as asthma, and exposure to fine particles is
associated with various additional human health effects (the
PM Concentrations indicator, p. 2-29) (U.S. EPA, 2004).
This indicator shows trends in ambient air concentra-
tions of ozone and particulate matter in the U.S. coun-
ties at the U.S./Mexico border area in comparison to
U.S. national trends, where appropriate. These trends are
shown for the longest duration of time supported by the
underlying monitoring data. For ozone, this indicator
reports the average of the fourth highest daily maximum
8-hour concentrations for three consecutive calendar
years. For PM1Q, this indicator reports the 3-year average
of the second highest 24-hour concentrations. For PM2 5,
this indicator reports the 3-year average of the seasonally
•weighted annual average concentration. For ozone and
PM25, national trend lines are also depicted because the
statistics used to report data in this indicator are the same
as those used in the corresponding national indicators.
For PM1Q, national data are not presented, because this
indicator tracks data over 3-year averaging periods, while
the national indicator tracks data over single-year inter-
vals. This indicator is based on all monitoring stations
that operated on the U.S. side of the border during this
time period.
In EPA Region 6, ozone monitoring data from border
locations were collected in Dona Ana County in New
Mexico and El Paso, Brewster, Webb, Hidalgo, and Cam-
eron Counties in Texas. In EPA Region 9, ozone monitor-
ing data from border locations were collected in the coun-
ties of Cochise, Pima, and Yuma in Arizona and Imperial
and San Diego in California. PM1Q sampling data for EPA
Region 6 are from Cameron, Hidalgo, Webb and El Paso
Counties in Texas and Dona Ana, Luna, and Grant Coun-
ties in New Mexico. PM2 5 data were available for all of
the above counties except for Luna County, New Mexico.
For EPA Region 9, PM1Q monitoring data were collected
in the counties of Cochise, Pima, Santa Cruz, and Yuma
in Arizona and Imperial and San Diego in California. For
EPA Region 9, PM2 5 monitoring data were collected in
the counties of Cochise, Pima, and Santa Cruz in Arizona
and Imperial and San Diego in California.
What the Data Show
Trends for 8-Hour Ozone Concentrations
In EPA Region 6, average border ozone concentrations
decreased by 11 percent between the 1986-1988 and 1992-
1994 time periods (a smaller decrease than the national aver-
age, which was 13 percent) and by 4 percent between the
1993-1995 and 2004-2006 periods (again, smaller than the
national average decrease of 11 percent) (Exhibit 2-47, panel
A). In EPA Region 9, however, border ozone concentra-
tions decreased by 6 percent between the 1986-1988 and
1992-1994 time periods and then decreased by 11 percent
between the 1993-1995 and 2004-2006 periods.
Trends for 24-Hour PM10 Concentrations
In EPA Region 6, the second highest 24-hour PM1Q con-
centrations at border monitoring sites varied considerably
over the period of record, most likely due to variation in
meteorological conditions (e.g., rainfall, wind speed) and
soil erosion (Exhibit 2-47, panel B); no clear long-term
trend is apparent from the data. In EPA Region 9, on the
other hand, corresponding PM1Q concentrations at bor-
der monitoring sites did not exhibit such strong temporal
variations, and the average second highest 24-hour concen-
tration at border monitoring sites for the 2004-2006 time
frame was 37 percent lower than that for the 1988-1990
time frame.
Trends for Annual Average PM2 5 Concentrations
Between 1999-2001 and 2004-2006, average annual ambi-
ent PM2 5 exhibited no clear trend in the border counties of
EPA Region 6, but decreased by 17 percent in the border
counties of EPA Region 9 (Exhibit 2-47, panel C). Average
annual ambient PM2 5 concentrations decreased 10 percent
nation-wide over the same period.
Indicator Limitations
• Many counties along the U.S./Mexico border do not
have ambient air quality monitors; these counties are not
characterized by this indicator.
• This indicator does not include data from the Mexican
side of the border. When a technical review concludes
the quality of these data is appropriate for the intended
use, the indicator will be updated.
• Short-term trends in PM1Q concentrations are often
highly dependent on meteorological conditions. The
maximum concentration for a given site can be influ-
enced by wind-blown dust and will exhibit considerable
variations from day to day. Trends over the longer term
are far less likely to be influenced by unusual meteoro-
logical conditions.
EPA's 2008 Report on the Environment
2-57
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INDICATOR
Ozone and Particulate Matter Concentrations for
U.S. Counties in the U.S./Mexico Border Region (continued)
• The long-term ozone trends are derived from an increas-
ing number of monitors over the course of time from
1986 to 2006, but an analysis of the limited number of
border sites that have full periods of record show that the
slopes of the trends are similar to those in this indicator.
• Average air pollutant concentrations may mask higher
values in some areas along the border and in the nation.
• Because most of the monitoring sites are located in urban
areas, the trends might not accurately reflect conditions
outside the immediate urban monitoring areas.
Data Sources
Summary data in this indicator were provided by EPA's
Office of Air Quality Planning and Standards, Region
6, and Region 9. These summaries were based on ozone
and PM ambient air monitoring data in EPA's Air Quality
System (U.S. EPA, 2007) (http://www.epa.gov/ttn/airs/
airsaqs/). Trends in this indicator are based on the subset
of ozone and PM monitoring stations located in counties
along the U.S./Mexico border that have sufficient data to
assess trends over the period of record.
References
U.S. EPA (United States Environmental Protection
Agency). 2007. Data from the Air Quality System.
Accessed 2007.
U.S. EPA. 2006. Air quality criteria for ozone and related
photochemical oxidants. EPA/600/R-05/004aF-cF.
Research Triangle Park, NC.
U.S. EPA. 2004. Air quality criteria for particulate mat-
ter (October 2004). EPA 600/P-99/002aF-bF. Research
Triangle Park, NC.
U.S. EPA. 2003. Border 2012: U.S.-Mexico environmental
program. EPA/160/R-03/001. Washington, DC.
Ambient Concentrations of Manganese Compounds in
5
ion
Ianganese is a naturally occurring metal that is ubiq-
uitous in the environment. Exposure to low levels
of manganese in the diet is considered to be nutritionally
essential for people and animals (ATSDR, 1997). How-
ever, exposures to elevated concentrations of manganese
are harmful to human health and have been associated with
subtle neurological effects, such as slowed eye-hand coordi-
nation. Manganese compounds are hazardous air pollutants
emitted by iron and steel production plants, power plants,
coke ovens, and many smaller metal processing facilities.
Manganese also may be contributed in border communities
by vehicles using Canadian fuel with the additive methylcy-
clopentadienyl manganese tricarbonyl (MMT).
Although manganese compounds are air pollutants of
concern nation-wide, they are of special concern in EPA
Region 5. The 1999 National Emissions Inventory showed
that Region 5 had the highest manganese emissions of all
EPA Regions, contributing 36.6 percent of all manganese
compounds emitted nation-wide (U.S. EPA, 2005a). Emis-
sions from industrial sources in Region 5 occurred from
various facilities, such as those that manufacture steel or
process iron ores and alloys for steelmaking. Between 1988
and 2003, manganese emissions from point sources declined
both nationally (26.2 percent) and in EPA Region 5 (36.7
percent). Year-to-year variability in manganese emissions is
high, however, and recent emissions data (1996-2003) sug-
gest a -weaker trend: emissions dropped 7.6 percent and 12.4
percent nation-wide and in EPA Region 5, respectively (U.S.
EPA, 2005b).
EPA's National Air Toxics Assessment (NATA) is
intended to provide a better understanding of the health
risks resulting from inhalation exposure to air toxics. Based
on 1999 emissions inventories, the most recent NATA
results (U.S. EPA, 2006) identify manganese compounds as
the largest contributor to neurological non-cancer health
risk in the U.S. Modeled estimates of ambient manganese
compounds in all 3,222 U.S. counties show that among the
50 counties -with the highest concentrations nation-wide, 20
are located in EPA Region 5.
This indicator presents ambient concentrations of man-
ganese compounds measured as total suspended particu-
lates (TSP) by direct monitoring. This indicator addresses
manganese in the TSP fraction (not PM1Q or PM2 5) because
it is the most complete dataset in EPA Region 5 in terms of
2-58
EPA's 2008 Report on the Environment
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Ambient Concentrations of Manganese Compounds in
EPA Region 5 (continued)
geographic and temporal coverage. TSP metals data have
been commonly used in human health risk assessments. EPA
recently has begun to recommend PM1Q as the most appro-
priate fraction for evaluating people's exposure to toxic met-
als (U.S. EPA, 2002), but PM1Q metals data are sparse at this
time, both nationally and in EPA Region 5. Data from a
limited number of sites in EPA's Air Quality System (AQS)
•with collocated PM1Q and TSP speciation monitors sug-
gest that the proportion of manganese in PM1Q versus TSP
is about 50 percent at most sites and can be as high as 75
percent. TSP manganese data therefore should be consid-
ered a conservative estimate of PM1Q manganese exposures.
PM25 metals data are plentiful since the establishment of the
Speciation Trends Net-work in 2000, but this size fraction is
believed to underestimate human exposures.
Data \vere considered for 58 monitoring sites in EPA
Region 5 that had a complete year of data reported to
the AQS national database in 2006. Average manganese
concentrations were calculated for each monitoring site.
A concentration trend was determined using a subset
of 21 of the monitoring sites with six or more complete
years of data between 2000 and 2006. As annual average
concentrations are representative of long-term inhalation
exposures, the ambient monitoring data are displayed in
comparison with the manganese reference concentration
(RfC). The RfC is an estimate of a chronic inhalation
exposure that is likely to be -without appreciable risk of
adverse non-cancer effects during a lifetime. The RfC
for manganese is 0.05 micrograms per cubic meter (jig/
m3), based on impairment of neurobehavioral function in
people. At exposures increasingly greater than the RfC,
the potential for harmful effects increases (ATSDR, 1997;
U.S. EPA, 1999). Monitoring sites -were classified into dif-
ferent categories based on land use as defined in AQS.
What the Data Show
In 2006, the median average annual ambient concentra-
tions of manganese as TSP in EPA Region 5 -were 0.024
(ag/m3 at the 15 residential sites, 0.024 (ig/m3 at the 16 sites
in commercial or high-traffic areas, and 0.046 (ig/m3 at
the 24 industrial sites (Exhibit 2-48). The average annual
ambient concentration of manganese at three predomi-
nantly agricultural and forest sites in EPA Region 5 -was
0.02 (ig/m3, but this is not depicted in the figure due to the
limited number of monitoring sites to characterize a distri-
bution. Greater concentration differences -were observed in
the 90th percentile values: below 0.1 (ig/m3 at the residen-
tial, commercial, and high-traffic sites, compared to 0.39
(ig/m3 at the predominantly industrial sites. In 2006, 18 of
the 58 sites had average manganese concentrations higher
than the RfC; 12 of these sites -were categorized as indus-
trial, two commercial or high-traffic, and four residential.
Exhibit 2-48. Ambient manganese
concentrations in EPA Region 5 by land use
category, 2006ab
0.4
ol 0.3
O) ^
ro in.
S s
Jf .2 0.2
ro ra
< § 0.1
o
o
0.0
RfCc = 0.05 ug/m3
Commercial or
high-traffic areas
Industrial
Residential
Land use category
Coverage: 55 monitoring sites in
EPA Region 5, with 16 sites in
commercial or high-traffic land use
areas, 24 sites in industrial areas,
and 15 sites in residential areas.
Concentrations are for manganese
in total suspended particulate
matter.
=The reference concentration (RfC) is an estimate of a continuous
inhalation exposure to the human population (including sensitive
subgroups) that is likely to be without an appreciable risk of
deleterious effects during a lifetime.
Data source: U.S. EPA, 2007
90th percentile
75th percentile
Median
25th percentile
10th percentile
The average annual manganese concentration averaged
across 21 trend sites showed a 28 percent decline between
2000 and 2006 (Exhibit 2-49). Additional years of data
may be needed to confirm this trend. The trend sites had
the folio-wing land use designations: commercial and high-
traffic (six sites), industrial (nine sites), and residential (six
sites). None of the trend sites had agricultural or forest land
use designations.
Indicator Limitations
• AQS data represent several sites per state, but do not have
full geographic or temporal coverage. Some emissions
"hotspots" are included, -while others may exist that have
not been monitored.
• The land use categories are only generally indicative
of the area represented by an ambient air monitor. For
example, a site categorized as "industrial" may adjoin a
densely populated community -where many residents are
exposed to ambient pollution.
EPA's 2008 Report on the Environment
2-59
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INDICATOR
Ambient Concentrations of Manganese Compounds in
EPA Region 5 (continued)
Data Sources
Summary data in this indicator were provided by EPA
Region 5, based on ambient air monitoring data for manga-
nese compounds reported in EPA's AQS (U.S. EPA, 2007)
(http://www.epa.gov/ttn/airs/airsaqs/). Trends in this indi-
cator are based on the subset of monitoring stations located
in EPA Region 5 that have sufficient manganese concentra-
tion data to assess trends over the period of record.
References
ASTDR (Agency for Toxic Substances and Disease Reg-
istry). 1997. Toxicological profile for manganese (update).
Draft for public comment. Atlanta, GA: U.S. Department of
Health and Human Services.
U.S. EPA (United States Environmental Protection Agency).
2007. Data from the Air Quality System. Accessed 2007.
U.S. EPA. 2006. 1999 national-scale air toxics assessment.
February.
U.S. EPA. 2005a. 1999 National Emissions Inventory data.
August.
U.S. EPA. 2005b. 1999 Toxics Release Inventory data.
December.
U.S. EPA. 2002. Quality assurance guidance document—
model quality assurance project plan for the national air
toxics trends stations. Washington, DC.
U.S. EPA. 1999. Integrated Risk Information System (IRIS)
on manganese. Washington, DC.
Exhibit 2-49. Ambient manganese
concentrations in EPA Region 5, 2000-20063
tr 0.20
0.16
90% of sites have
concentrations below
10% of sites have concentrations below this line
< 0.00
2000
2001
2002
2003
Year
2004
2005
2006
Coverage: 21 monitoring sites in EPA Region 5 (out of a total of
58 sites measuring manganese in 2006) that have sufficient data
to assess manganese trends since 2000.
Concentrations are for manganese in total suspended particulate
matter.
=The reference concentration (RfC) is an estimate of a continuous
inhalation exposure to the human population (including sensitive
subgroups) that is likely to be without an appreciable risk of
deleterious effects during a lifetime.
Data source: U.S. EPA, 2007
2.2.3 Discussion
What These Indicators Say About Trends
in Outdoor Air Quality and Their Effects on
Human Health and the Environment
Criteria Pollutants and Their Precursors
Because of regulatory monitoring and reporting requirements,
criteria pollutants have some of the most extensive data avail-
able to support National Indicators for emissions and ambient
air concentrations. Nation-wide, air emissions of every criteria
pollutant (or the corresponding precursors) have decreased
between 1990 and 2002—the period of record covered by
the National Emissions Inventory. During that time frame,
substantial decreases in air emissions were observed for carbon
monoxide, nitrogen oxides, particulate matter, sulfur dioxide,
and volatile organic compounds. Even more pronounced
emissions reductions occurred for lead, but this decrease
extends back to the 1970s. With few exceptions, downward
trends in criteria pollutant emissions were observed in the ten
EPA Regions, similar to the corresponding national trends.
Consistent with the emissions trends, every criteria pollut-
ant showed decreasing ambient air concentrations based on
aggregate measurements from the nation's ambient air moni-
toring system, which measures levels of air pollution primar-
ily in urban and suburban areas. The magnitude of air quality
improvements, observed both nationally and in all ten EPA
Regions, varies across pollutants. Carbon monoxide, lead,
and nitrogen dioxide concentrations decreased considerably
between 1980 and the present, and ambient concentrations of
these three pollutants in most or all areas in the U.S. are now
below the level of the corresponding air quality standards that
protect human health and the environment. In contrast, air
2-60
EPA's 2008 Report on the Environment
-------
quality improvements for ozone and particulate matter (par-
ticularly PM25) were less pronounced; and, based on monitor-
ing data collected in 2006 and reported in EPA's Air Quality
System, ambient concentrations of ozone, particulate matter,
or both pollutants in 105 metropolitan statistical areas where
approximately 138 million people lived were greater than the
level of their corresponding health-based standards.6 In short,
every criteria pollutant has showed improving air quality over
the past one or two decades, but the progress has been slowest
for the two pollutants—ozone and PM2 5—most influenced by
meteorology and secondary formation processes.
The nation-wide trends and those presented for the ten EPA
Regions are based on aggregate statistics across numerous moni-
toring stations and may not reflect air quality trends at finer scales
or for different subsets of monitoring stations. For example, the
significant downward trend in ozone in EPA Region 9 is largely
influenced by air quality improvements in Los Angeles and other
metropolitan areas in southern California. In other urban areas in
EPA Region 9, ozone improvements have been more modest or
even different directionally.7 Similarly, PM2 5 concentrations have
increased over the last 5 years at selected monitoring stations near
the border between U.S. and Mexico (the Ozone and PM Con-
centrations Along U.S./Mexico Border indicator, p. 2-56), even
though the national trend for this pollutant is downward.
The ROE indicators on criteria pollutants' environmental
effects are limited to three issues. First, long-term moni-
toring data show that wet deposition of acidic sulfates and
nitrates decreased between 1989 and 2006, consistent with
the decreased emissions for sulfur dioxide and nitrogen oxides
over roughly the same time frame. As a result of the decreased
acid deposition, many surface waters throughout the Adiron-
dack Mountains, the Northern Appalachian region, and New
England have begun to recover from past acidification (the
Lake and Stream Acidity indicator, p. 2-42). Second, data
on ozone injury to forest plants are sufficient for establish-
ing national and regional baseline conditions against which
future data can be compared. These baseline conditions show
considerable variation in ozone damage across EPA Regions
(the Ozone Injury to Forest Plants indicator, p. 2-24). Third,
visibility in protected areas (e.g., National Parks, Wilderness
Areas) has increased between 1992 and 2004 (the Regional
Haze indicator, p. 2-33), consistent with a corresponding
decrease in fine particle concentrations.
Overall, for criteria pollutants, the ROE indicators provide
fairly complete information on outdoor air quality trends,
but limited insights on associated health and environmental
effects. As expected, emissions trends are generally consistent
\vith trends observed among corresponding ambient concen-
trations and, \vhere data are available, effects.
Air Toxics and Other Air Pollutants
Between 1990 and 2002, nation-wide emissions aggregated
across 188 air toxics (hazardous air pollutants) decreased (the
Air Toxics Emissions indicator, p. 2-48). Decreased emissions
•were also observed for two air toxics of particular interest:
benzene and mercury (the Mercury Emissions indicator, p.
2-46). However, sufficiently complete and consistent monitor-
ing data currently cannot support ROE indicators for ambient
concentration of air toxics, with two exceptions. First, ambi-
ent air concentrations of benzene at 23 monitoring sites across
the nation decreased 55 percent between 1994 and 2006—a
decrease reasonably consistent with corresponding emissions
reductions. Second, ambient air concentrations of manganese
compounds measured at 21 monitoring sites in EPA Region 5
decreased by 28 percent between 2000 and 2006, though the
period of record evaluated may be too short to consider this
decrease an actual air quality trend.
Stratospheric Ozone Issues
Since 1990, the U.S. phased out most production and import
of ozone-depleting substances. Consequently, consumption
of ozone-depleting substances in the U.S. decreased during
this last decade, along with globally representative ambient
air concentrations of ozone-depleting substances in the lower
atmosphere (the Concentrations of Ozone-Depleting Sub-
stances indicator, p. 2-52). While such decreases are expected
to help restore the stratospheric ozone layer, stratospheric
ozone levels over North America actually decreased slightly
since the 1980s, though have remained largely unchanged in
the last decade (the Ozone Levels over North America indica-
tor, p. 2-54). This trend is due to various factors, including
ongoing use of ozone-depleting substances worldwide and the
fact that ozone-depleting substances are extremely long-lived
in the atmosphere.
Limitations, Gaps, and Challenges8
The 23 ROE indicators in this section characterize trends for
numerous important outdoor air quality issues, but also have
notable limitations. All emissions indicators, for instance,
are partly based on estimates. Although these estimates have
inherent uncertainties, the emissions inventory data are
believed to be of high quality and are periodically updated to
remain consistent with the current scientific understanding of
emissions from different source categories. The main limita-
tion of the ambient concentration indicators is the monitoring
sites' limited spatial coverage. These indicators are compos-
ites of air quality measurements taken across the country,
but primarily in populated areas: they may not totally reflect
trends for rural settings. While the national trends for crite-
ria pollutants and benzene are toward improved air quality,
This statement is based on the current particulate matter standards and on the
1997 8-hour ozone standard (0.08 ppm). Future versions of the ROE will be
based upon the recently promulgated 2008 ozone standard (0.075 ppm) or on
the NAAQS in effect at the time.
U.S. Environmental Protection Agency. 2004.The ozone report: Measuring
progress through 2003. EPA/454/K-04/001. Research Triangle Park, NC.
While the ROE indicators provide valuable information about trends in
outdoor air quality, the indicators are more limited in their ability to describe
trends in associated effects on human health and the environment. As
described in Chapter 1, it is difficult to establish causal relationships between
specific stressors and outcomes. In the case of outdoor air, there are few
"effects" indicators with clear causal linkages.
EPA's 2008 Report on the Environment
2-61
-------
ambient concentrations of these pollutants can vary greatly on
a local scale. In certain areas, such as those experiencing rapid
population growth or near newly constructed point sources,
ambient air concentrations of selected pollutants may be
increasing, contrary to the national trends; conversely, ambi-
ent air concentration in other parts of the country are decreas-
ing more rapidly than the national trends depict.
Though the emissions and ambient concentration indicators
are reasonably complete for the criteria pollutants, gaps in
nationally representative indicators remain for most air toxics
and other air pollutants. However, a large number of these air
toxics and other air pollutants are released by a small number
of sources nation-wide, and these pollutants' emissions and
ambient concentrations are more appropriately tracked at the
local level, rather than with National Indicators. Another gap
in National Indicators is for air toxics and other air pollutants
that are ubiquitous in the nation's outdoor air (e.g., mobile
source air toxics). Although nation-wide trends in air toxics
concentrations have been estimated -with models, nationally
representative ambient air monitoring data on air toxics -would
provide EPA -with a more direct measure of important outdoor
air quality trends. Many local-scale monitoring net-works have
tracked trends for some of these pollutants, but nation-wide
indicators could not be developed for pollutants other than
benzene due to limited spatial coverage of monitoring sites,
use of differing sampling and analytical methods over the
years, inconsistent application of quality assurance and quality
control practices, and other factors.
ROE indicators for ambient concentrations of some com-
mon air toxics are expected to be developed in coming years,
based on measurements currently being collected in mul-
tiple net-works. The National Air Toxics Trends Stations, for
instance, are a recently implemented net-work of monitoring
sites specifically designed to characterize long-term trends in
several air toxics believed to account for the greatest health
risks nation-wide.9 Additionally, data being collected as part of
a nation-wide PM2 5 speciation net-work are expected to pro-
vide long-term trend information on concentrations of metals,
ions, and carbon constituents of fine particulate matter.10
Finally, ongoing operation of the Mercury Deposition Net-
work (part of the National Atmospheric Deposition Program)
is gathering data to support trends analysis on atmospheric
deposition of mercury—an issue of particular significance
•when evaluating contamination levels in fish and shellfish.
National-level exposure and effects indicators can help EPA
better characterize nationwide trends in outdoor air quality and
their effects, but key challenges complicate efforts to develop
these. For example, ambient concentration data do not quantify
exposures, because ambient air monitoring equipment measures
air quality at fixed outdoor locations, while people breathe air in
U.S. Environmental Protection Agency. 2004. National monitoring strategy:
Air toxics component. Final draft. July,
U.S. Environmental Protection Agency. 1999. Strategic plan: Development
of the particulate matter (PM25) quality system for the chemical speciation
monitoring trend sites. April 16, 1999.
Jantunen, M., O. Hanninen, K. Koistinen, and J.H. Hashim. 2002. PM
measurements: Personal and indoor air monitoring. Chemosphere 49:993-1007.
multiple indoor and outdoor settings during a typical day. Actual
human exposure to air pollution can be measured through use
of personal monitoring devices, which sample the air that people
breathe as they move through different microenvironments.
Some researchers have used such devices to quantify exposures
to specific pollutants in some locations.11 However, conduct-
ing such studies on a national scale over an extended time frame
•would be an extremely resource-intensive task. Consequently, no
nationally representative studies currently support ROE indica-
tors that characterize exposure to outdoor air pollutants. Another
gap pertaining to effects attributed to outdoor air quality is that
the scientific understanding of how all air pollutants, whether
acting alone or in combination, can affect human health and the
environment is incomplete and continues to evolve.
While the indicators document what is currently known about
selected outdoor air quality issues, ongoing scientific research
continues to broaden the knowledge base on many important
topics, ranging from designing innovative emissions control
technologies to enhancing atmospheric fate and transport mod-
eling to developing metrics that better connect air quality to
public health and ecological outcomes.
2.3 What Are the
Trends in Greenhouse
Gas Emissions and
Concentrations?
2.3.1 Introduction
Greenhouse gases, such as carbon dioxide, methane, nitrous
oxide, and certain synthetic chemicals, trap some of the
Earth's outgoing energy, thus retaining heat in the atmo-
sphere.12 Changes in the radiative balance of the Earth—the
balance between energy received from the sun and emitted
from Earth—as a result of this heat trapping alter -weather
patterns and climates at global and regional scales.13 Natural
factors, such as variations in the sun's output, volcanic activ-
ity, the Earth's orbit, the carbon cycle, and others, also affect
the radiative balance.14 However, increasing concentrations of
greenhouse gases due to human activity are affecting various
aspects of climate, such as surface air temperature and subsur-
face ocean temperature. Since 1750, the net global effect of
human activities has been one of-warming.15 Human health,
agriculture, -water resources, forests, -wildlife, and coastal areas
all are vulnerable to climate change.16 The purpose of this
12 National Research Council. 2005. Radiative forcing of climate change:
Expanding the concept and addressing uncertainties, pp. 1, 9, vii, and others.
13 Ibid.,p. 11.
14 Ibid., p. 13.
15 Intergovermental Panel on Climate Change. 2007. Climate change 2007: The
physical science basis (fourth assessment report), 2007. p. 3.
16 National Research Council. 2005. Radiative forcing of climate change:
Expanding the concept and addressing uncertainties, pp. 4, 19-20.
2-62
EPA's 2008 Report on the Environment
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section is to evaluate long-term trends in air emissions and
ambient concentrations of greenhouse gases that are contribut-
ing to climate change, but not to evaluate the effects that these
emissions and concentrations cause.17
Though the focus of this question is on greenhouse gases,
related factors can also alter the Earth's climate. Certain
radiatively important substances, like black carbon (soot), are
technically not greenhouse gases due to their physical state,
but they nonetheless affect the flow of energy through the
atmosphere. Some of these substances, such as sulfate aero-
sols, have negative radiative forcings that can lead to cooling
effects. Another related factor is albedo (the reflectivity of the
Earth's surface), which affects the portions of absorbed and
outgoing energy. Natural and human factors can affect albedo
on a global scale (through changes in large-scale features
like the polar ice caps) or on a local or regional scale (e.g., by
increased amounts of dark paved surfaces that absorb energy).
Although this question does not address radiatively important
substances that are not greenhouse gases or non-chemical fac-
tors like albedo, these influences are also important to under-
standing the planet's energy balance and the ways human
activities may affect that balance.18 Quantitative information
on the relative radiative forcings from greenhouse gases, other
radiatively important substances, and selected non-chemical
factors is available in other publications.19
Some greenhouse gases are emitted exclusively from human
activities (e.g., synthetic halocarbons). Others occur natu-
rally but are found at elevated levels due to human inputs
(e.g., carbon dioxide). The anthropogenic sources result from
energy-related activities (e.g., combustion of fossil fuels in
the electric utility and transportation sectors), agriculture,
land-use change, waste management and treatment activities,
and various industrial processes. Major greenhouse gases and
emissions sources include:
• Carbon dioxide, widely reported as the most important
anthropogenic greenhouse gas.20 Carbon dioxide occurs
naturally as part of the global carbon cycle, but human
activities have increased atmospheric loadings through
combustion of fossil fuels and other emissions sources.21
Natural sinks that remove carbon dioxide from the atmo-
sphere (e.g., oceans, plants) help regulate carbon dioxide
concentrations, but human activities can disturb these
processes (e.g., deforestation) or enhance them.
• Methane, which comes from many sources, including
human activities such as coal mining, natural gas distri-
bution, waste decomposition in landfills, and digestive
17 In a general sense, climate change is conceptually connected to every other
theme in this report.The broadest discussion of potential effects associated
with greenhouse gases in this report is in Section 6.5, which discusses critical
physical and chemical attributes of ecosystems, including ROE indicators that
track changes in air temperature, precipitation, sea surface temperature, and
sea level—all of which affect ecosystems.
18 Detailed information on these related factors can be found in various scientific
publications, such as those prepared by the Intergovernmental Panel on Climate
Change, a panel formed by the World Meteorological Organization to compile
and synthesize the growing body of scientific literature on climate change.
19 Intergovernmental Panel on Climate Change. 2007. Climate change 2007:
the scientific basis (fourth assessment report). Cambridge, United Kingdom:
Cambridge University Press, p. 4.
processes in livestock and agriculture.22 Natural sources
include wetlands and termite mounds.
• Nitrous oxide, which is emitted during agricultural and
industrial activities, as well as during combustion of solid
•waste and fossil fuels.
• Various synthetic chemicals, such as hydrofluorocar-
bons, perfluorocarbons, sulfur hexafluoride, and other syn-
thetic gases, \vhich are released as a result of commercial,
industrial, or household uses.
• Many other gases that are known to trap heat in the
atmosphere. Examples include water vapor, which occurs
naturally as part of the global water cycle, and ozone,
•which occurs naturally in the stratosphere and is found in
the troposphere largely due to human activities.
Each gas has a different ability to absorb heat in the atmo-
sphere, due to differences in its atmospheric half-life and the
amount and type of energy that it absorbs. For example, it
•would take thousands of molecules of carbon dioxide to equal
the warming effect of a single molecule of sulfur hexafluo-
ride—the most potent greenhouse gas, in terms of ability to
absorb heat, evaluated by the Intergovernmental Panel on Cli-
mate Change.23 To facilitate comparisons between gases that
have substantially different properties, the Panel has developed
a set of scaling factors called "global warming potentials," as
discussed further in the indicator write-ups.
The remainder of this section focuses on greenhouse gas
emissions and concentrations, given that greenhouse gases
can affect radiative forcings, thus leading to climate change.
However, climate change can also affect atmospheric concen-
trations of many substances through various feedback mecha-
nisms. Other publications provide detailed information on the
broader issues of how climate change can affect air quality.24
2.3.2 ROE Indicators
To characterize trends in greenhouse gases, this chapter
presents two indicators—one describing emissions from U.S.
sources and the other describing concentrations (Table 2-3).
The U.S. Greenhouse Gas Emissions indicator covers the
1990-2005 period, with data from EPA's Inventory of U.S.
Greenhouse Gas Emissions and Sinks. This inventory is a
database that tracks both greenhouse gas emissions directly
attributable to human activities and greenhouse gas sinks (e.g.,
sequestration of carbon in forests). The indicator stratifies
emissions into trends for different gases and source categories.
20 Ibid., p. 2.
21 US. Environmental Protection Agency. 2006. Inventory of US. greenhouse
gas emissions and sinks: 1990-2004. EPA/430/R-06/002.Washington, DC.
22 National Research Council. 2001. Climate change science:An analysis of
some key questions. Washington, DC: National Academy Press.
23 Intergovernmental Panel on Climate Change. 2007. Climate change 2007:
The scientific basis (fourth assessment report). Cambridge, UK: Cambridge
University Press.
24 Intergovermental Panel on Climate Change. 2007. Climate change 2007:
Impacts, adaptation, and vulnerability (fourth assessment report). Cambridge,
UK: Cambridge University Press.
EPA's 2008 Report on the Environment
2-63
-------
Emissions are -weighted by "global warming potentials" to
facilitate comparison among the gases.
The Greenhouse Gas Concentrations indicator summarizes
both direct measurements of ambient air concentrations from
the last half-century and observations for earlier time frames
based on chemical analyses of air bubbles found in ice core sam-
ples. The gases in these bubbles represent the outdoor air that
\vas trapped in ice at the time the ice was formed. Combined,
these two measurements provide extensive historical coverage
for the atmospheric concentrations of greenhouse gases.
Many greenhouse gases are extremely long-lived in the atmo-
sphere, \vith some remaining airborne for tens to hundreds of
years after being released. These long-lived greenhouse gases
become globally mixed in the atmosphere, and their concen-
trations reflect past and recent contributions from emissions
sources worldwide. This context is an important backdrop for
the two greenhouse gas indicators in this section: increasing
atmospheric concentrations of greenhouse gases is a global
issue, resulting from emissions from sources in the U.S. com-
bined \vith emissions from sources in other countries.
Table 2-3. ROE Indicators of Trends in Greenhouse Gas Emissions and Concentrations
National Indicators
U.S. Greenhouse Gas Emissions
Atmospheric Concentrations of Greenhouse Gases
Section
2.3.2
2.3.2
2-64
2-66
INDICATOR
U.S. Greenhouse Gas Emissions
The Earth's climate is determined by the balance
between energy received from the sun and energy
emitted back to space from the Earth and its atmosphere.
Certain gases in the atmosphere, such as carbon dioxide
(CO2), methane (CH4), nitrous oxide (N2O), water vapor,
and others, trap some of the outgoing energy, retaining
heat in the Earth's atmosphere. These are the so-called
"greenhouse gases" (GHGs). The best understood GHGs
emitted by human activities are CO2, CH4, N2O, and cer-
tain fluorinated compounds.
Changes in GHG emissions are influenced by many long-
term factors, including population and economic growth,
land use, energy prices, technological changes, and inter-
annual temperatures. On an annual basis, combustion of
fossil fuels, which accounts for most GHG emissions in the
U.S., generally fluctuates in response to changes in general
economic conditions, energy prices, weather, and the avail-
ability of non-fossil alternatives (U.S. EPA, 2007).
This indicator uses data and analysis from the Inventory
of U.S. Greenhouse Gas Emissions and Sinks (U.S. EPA,
2007), an assessment of the anthropogenic sources and
sinks of GHG emissions for the U.S. and its territories for
the 1990-2005 period. The inventory constitutes estimates
derived from direct measurements, aggregated national sta-
tistics, and validated models in most source categories. An
extensive discussion of the methods for each source type
and gas and the uncertainties inherent in the calculations is
available in EPA (2007) and its Annex 7.
The indicator is expressed in terms of CO2 equivalents,
meaning that emissions of different gases are -weighted
by their "global warming potential" (GWP). A GWP is a
measure of how much a given mass of GHG is estimated
Exhibit 2-50. Greenhouse gas emissions in the
U.S. by gas, 1990-2005
8,000
7,000
6,000
5,000
_CD CD
^1 3,000
c _o
•| "° 2,000
m 1,000
MFCs, PFCs, and SF6
Nitrous oxide
Methane
Carbon dioxide
o
'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05
Year
aTeragrams of carbon dioxide equivalents are the units
conventionally used in greenhouse gas inventories prepared
worldwide. For reference, one teragram equals one million metric
tons.
bHFCs are hydrofluorocarbons, PFCs are perfluorocarbons, and SF6
is sulfur hexafluoride.
Data source: U.S. EPA, 2007
to contribute to radiative forcing that contributes to global
•warming over a selected period of time, compared to
the same mass of CO2, for which the GWP is 1.0. EPA is
mandated to use the GWPs documented in the Intergov-
ernmental Panel on Climate Change's Second Assessment
Report (IPCC, 1996), which characterize GWP for a
2-64
EPA's 2008 Report on the Environment
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INDICATOR
LS. Greenhouse Gas Emissions
(continued)
100-year time horizon—the effect of the gas on radiative
forcing over 100 years. Annex 6 of the U.S. GHG inven-
tory includes extensive information on GWPs and how
they relate to emissions estimates (U.S. EPA, 2007).
This indicator focuses on the six types of compounds
currently covered by agreements under the United Nations
Frame-work Convention on Climate Change. These com-
pounds are CO2, CH4, N2O, hydrofluorocarbons (HFCs),
perfluorocarbons (PFCs), and sulfur hexafluoride (SF ). This
indicator does not include emissions estimates for substances
such as chlorofluorocarbons (CFCs), methyl bromide, sul-
fates, black carbon, and organic carbon. These substances are
excluded primarily because either their emissions have not
been quantified in the U.S. GHG inventory or they have
different types of effects on climate than those of the six
GHGs included in the U.S. inventory and, therefore, most
cannot be compared directly to the GHG. Combined, these
excluded substances may account for a considerable portion
of climate change, but their omission cannot be scientifically
quantified in comparable terms.
This indicator presents emissions data in units of tera-
grams of CO2 equivalents (Tg CO2 Eq). These units are
conventionally used in GHG inventories prepared world-
wide. For reference, one teragram (Tg) is equal to one mil-
lion metric tons.
What the Data Show
In 2005, total U.S. greenhouse gas emissions were 7,260
Tg CO2 Eq, up 16 percent from 1990 (Exhibit 2-50). CO2
is the primary greenhouse gas emitted by human activi-
ties, representing approximately 84 percent of greenhouse
gas emissions in 2005. From 1990 to 2005, total emissions
of CO2 increased by 1,028 Tg CO2 Eq (20 percent). CH4
represents the second largest U.S. GHG emission, account-
ing for 7 percent of net emissions in 2005. CH4 emis-
sions declined about 11 percent from 1990 to 2005, due
largely to reduced emissions from landfills and coal mining
operations. The primary sources of CH4 emissions include
decomposition of wastes in landfills, coal mine seepage,
natural gas systems, and enteric fermentation in domestic
livestock. NO constituted about 6 percent of net U.S.
GHG emissions in 2005; these emissions declined by about
3 percent from 1990 to 2005. The main anthropogenic
activities producing NO are agricultural soil management,
fuel combustion in motor vehicles, manure management,
nitric acid production, human sewage, and stationary fuel
combustion. Emissions of HFCs, PFCs, and SF^ accounted
6
for the remaining GHG emissions in 2005, and the aggre-
gate -weighted emissions of this group of gases rose by 74
Tg CO2 Eq since 1990, nearly doubling during that time
frame. Despite being emitted in smaller quantities than
the other principal greenhouse gases, HFCs, PFCs, and
SF are important because many of them have extremely
high global -warming potentials and, in the cases of PFCs
Exhibit 2-51. Greenhouse gas emissions in the
U.S. by industrial sector, 1990-2005
8,000
7,000
5_ 6,000
"o "
a> JS 5,000
E «
o'g. 4,000
-§ 3,000
2,000
.1 =1
-e 1,000
8
0
-1,000
-2,000
x Waste
Industrial processes
^Agriculture
Energy
Land use, land-use change, and forestry (sink)
'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05
Year
aTeragrams of carbon dioxide equivalents are the units conventionally
used in greenhouse gas inventories prepared worldwide. For
reference, one teragram equals one million metric tons.
Data source: U.S. EPA, 2007
and SF , atmospheric lifetimes of 700 to 50,000 years. The
emissions in this indicator are a continuation of the trend
of increasing GHG emissions observed over many decades,
•with total CO2-equivalent emissions increasing by about
one fifth since 1970 (U.S. EPA, 2007; RIVM/TNO,
2003). CO2 has constituted a slightly growing portion,
•while CH4 has been a declining component of the total.
Looking at GHG emissions by source shows that
energy-related activities (e.g., fuel combustion, gas leak-
age) accounted for 85 percent of total U.S. emissions in
2005 (Exhibit 2-51). Emissions due to energy use have
increased 19 percent between 1990 and 2005. Agriculture
is the second largest source of GHG emissions, accounting
for 7 percent of the total in 2005. Industrial processes and
•waste account for the remaining GHG emissions depicted
in Exhibit 2-51. This indicator does not depict trends in
GHG emissions from the use of solvents and other prod-
ucts or non-CO2 GHG emissions from land use change
and forestry, because GHG emissions from these source
categories account for less than 0.5 percent of the total
estimated emissions in EPA's GHG inventory.
U.S. GHG emissions are partly offset by uptake of
carbon and "sequestration" in forests, trees in urban areas,
agricultural soils, and landfilled yard trimmings and food
scraps. In aggregate, these removals of CO2 from the atmo-
sphere offset about 14 percent of total U.S. CO2 emissions
in 2005 (Exhibit 2-51).
EPA's 2008 Report on the Environment
2-65
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INDICATOR
U.S. Greenhouse Gas Emissions (continued)
With one-twentieth of the -world's population (U.S.
Bureau of the Census, 2006), the U.S. currently emits
about one-fifth of global GHGs: CO2, CH4, N2O, HFCs,
PFCs, and SF6 (Baumert et al, 2005).
Indicator Limitations
• This indicator does not yet include emissions of GHGs or
other radiatively important substances that are not explic-
itly covered by the United Nations Frame-work Con-
vention on Climate Change and its subsidiary protocol.
Thus, it excludes such gases as those controlled by the
Montreal Protocol and its Amendments, including CFCs
and hydrochlorofluorocarbons. Although the U.S. reports
the emissions of these substances as part of the U.S. GHG
inventory (see Annex 6.2 of the U.S. GHG inventory),
the origin of the estimates is fundamentally different
from those of the other GHG and therefore cannot be
compared directly -with the other emissions discussed in
this indicator.
• This indicator does not include aerosols and other emis-
sions that do affect radiative forcing and that are not
•well-mixed in the atmosphere, such as sulfate, ammonia,
black carbon, and organic carbon. Emissions of these com-
pounds are highly uncertain and have qualitatively differ-
ent effects than the six types of emissions in this indicator.
• This indicator does not include emissions of other com-
pounds—such as CO, NOx, nonmethane volatile organic
compounds, and substances that deplete the stratospheric
ozone layer—which indirectly affect the Earth's radiative
balance (for example, by altering GHG concentrations,
changing the reflectivity of clouds, or changing the dis-
tribution of heat fluxes).
• The U.S. GHG inventory does not account for "natu-
ral" emissions of GHGs, such as from wetlands, tundra
soils, termites, and volcanoes. These excluded sources are
discussed in Annex 5 of the U.S. GHG inventory (U.S.
EPA, 2007). The U.S. GHG inventory does include, in
its "Land Use, Land-Use Change, and Forestry" cat-
egory, emissions from changes in the forest inventory
due to fires, harvesting, and other activities, and from
agricultural soils.
Data Sources
The data used for this indicator were published in EPA's
inventory of greenhouse gas emissions and sinks for years
1990-2005 (U.S. EPA, 2007). Specifically, emissions by
GHG shown in Exhibit 2-50 are taken from Table ES-2 of
that reference, and emissions by industrial sector are taken
from Table ES-4.
References
Baumert, K., T. Herzog, andj. Pershing. 2005. Navigating
the numbers: Greenhouse gas data and international cli-
mate policy. Washington DC: World Resources Institute.
IPCC (Intergovenmental Panel on Climate Change). 1996.
Climate change 1995: The science of climate change.
Cambridge, UK: Cambridge University Press.
RIVM/TNO. 2003. Emission database for global atmo-
spheric research. Version 3.2. 2003.
U.S. Bureau of the Census. 2006. World POPClock;
USPOPClock.
U.S. EPA (United States Environmental Protection
Agency). 2007. Inventory of U.S. greenhouse gas emissions
and sinks: 1990-2005.
INDICATOR
Atmospheric Concentrations of Greenhouse Gases
The Earth's temperature depends mainly on the amount of
energy received from the sun, the portion reflected back
into space, and the extent to which the atmosphere retains
heat. Natural forces (e.g., volcanoes, changes in the Earth's
orbit) and human activities (e.g., emissions of so-called
"greenhouse gases," land use change) affect the amount of
energy held in the Earth-atmosphere system and therefore
affect the Earth's climate. Human activities in all countries
have altered the chemical composition of the atmosphere
by the emissions and accumulation in the atmosphere of
2-66
EPA's 2008 Report on the Environment
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INDICATOI
Atmospheric Concentrations of Greenhouse Gases (continued)
Exhibit 2-52. Global atmospheric concentrations of carbon dioxide (CC>2) over geological time and in
recent years
400
350
"E soo
o.
IT 250
_o
| 200
§
§ 150
o 100
50
A. 647,426 BC to 339 BC
B. 9002 BC to 1975 AD
C. 1958 AD to 2006 AD
-750,000 -500,000 -250,000
0 -10,000-8000 -6000 -4000 -2000 0 2000 1955 1965 1975 1985 1995 2005
Year (negative values = BC)
Trend lines and data sources:
647,426 BC to 339 BC
EPICA Dome C, Antarctica
(Siegenthaler et al., 2005)
- Vostok Station, Antarctica
(Barnola et al., 2003)
9002 BC to 1978 AD
Law Dome, East Antarctica
75-year smoothed
(Etheridge et al., 1998)
-Siple Station, West
Antarctica (Neftel et al.,
1994)
EPICA Dome C, Antarctica
(Fluckigeretal.,2002)
1958 AD to 2006 AD
Barrow, Alaska (Thoning
and Tans, 2000)
Cape Matatula, American
Samoa (Thoning and
Tans, 2000)
- South Pole, Antarctica
(Thoning and Tans,
2000)
- Mauna Loa, Hawaii
(NOAA-ESRL, 2007a)
Lampedusa Island, Italy
(Chamardetal.,2001)
Shetland Islands, Scotland
(Steel e et al., 2002)
Cape Grim, Australia (Steele
etal.,2002)
greenhouse gases. The primary gases that retain heat in the
atmosphere are water vapor, carbon dioxide (CO2), methane
(CH4), nitrous oxide (N2O), and certain manufactured gases
such as chlorofluorocarbons (CFCs), hydrochlorofluorocar-
bons (HCFCs), and sulfur hexafluoride (SF ).
Once emitted, gases remain in the atmosphere for vary-
ing amounts of time. Very "short-lived" compounds, such
as particulate matter (PM), remain airborne on average for
only hours or days. CH4 also has a relatively short average
lifetime, though much longer than PM, remaining in the
atmosphere for roughly 12 years. The half-life of CO emis-
sions is roughly 100 years (5 to 200 years: IPCC, 2001), but
about a quarter of emissions today will still be in the atmo-
sphere after hundreds of years and about one-tenth for hun-
dreds of thousands of years (Archer and Ganopolski, 2005;
Archer et al., 1998). Finally, many of the synthetic gases such
as halocarbons are extremely long-lived, remaining in the
atmospheric for hundreds or even tens of thousands of years.
When emissions—from the U.S. (the U.S. Greenhouse Gas
Emissions indicator, p. 2-64) as well as other countries—
remain in the atmosphere over long periods, they accumu-
late and are measured as atmospheric concentrations. U.S.
GHG emissions from 1890 to 2000 are estimated to have
contributed about one-fifth of the increase in global GHG
concentrations (den Elzen et al., 2005).
This indicator shows trends in the accumulation of the
following principal GHGs in the atmosphere: CO2, CH4,
NO, and selected halocarbons. Recent data are from
global net-works that monitor the concentrations of these
gases in the atmosphere. Geological data come from gas
measurements made of air trapped in ice cores at the time
the ice was formed. Because the gases shown in this indi-
cator remain in the atmosphere for long periods, they are
•well-mixed, so that measurements at individual locations
are globally representative. This indicator summarizes
GHG concentration measurements reported in a collec-
tion of studies published in the peer-reviewed literature.
In order to provide the most extensive temporal coverage,
EPA's 2008 Report on the Environment
2-67
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INDICATOR
Atmospheric Concentrations of Greenhouse Gases (continued)
Exhibit 2-53. Global atmospheric concentrations of methane (ChU) over geological time and in recent years
A. 646,729 BC to 281 BC
B. 8945 BC to 1980 AD
C. 1985 AD to 2006 AD
2,000
1,500
~ 1,000
8
o 500
-650,000 -500,000 -350,000 -200,000 -50,000 -10,000 -8
-6000 -4000 -2000 0 2000 1985
1990
1995
2000
2005
Year (negative values = BC)
Trend lines and data sources:
646,729 BC to 281 BC
- Vostok Antarctica ice core (Petit et al,
1999)
Greenland GRIP ice core (Blunierand
Brook, 2001)
- Greenland GISP2 ice core (Blunierand
Brook, 2001)
Antarctica Byrd Station ice core
(Blunierand Brook, 2001)
EPICA Dome C, Antarctica
(Spahni et al., 2005)
8945 BC to 1980 AD
1985 AD to 2006 AD
Law Dome, Antarctica (Etheridge etal.,
2002)
Various Greenland locations (Etheridge
etal., 2002)
• Greenland Site J (WDCGG, 2005)
EPICA Dome C, Antarctica (Fliickigeret
al., 2002)
- Cape Grim, Australia (NOAA-ESRL,
2007b)
Shetland Islands, Scotland (Steele
eta/., 2002)
Mauna Loa, Hawaii (NOAA-ESRL,
2007c)
this indicator aggregates comparable, high-quality data
from individual studies that each focused on different time
frames. None of the data in this indicator are based on
modeled concentrations.
What the Data Show
Exhibits 2-52 through 2-54 show the evolution of
concentrations of three principal GHGs in the atmo-
sphere over three intervals: geological time (hundreds
of thousands of years), the past 11,000 years, and recent
decades. The exhibits represent data sets covering a wide
range of latitudes, showing some latitudinal differences
in concentrations but also showing a high level of consis-
tency—indicating that the gases are well-mixed and that
the sampling can be considered spatially representative.
The graphs show patterns of large cycles of concentra-
tions over geological time, and they also depict increases
in concentrations in the industrial era (post-1780) that
exceed concentrations over the past hundreds of thousands
of years.
The concentration of CO , the most important
anthropogenic GHG, has varied considerably over
geological time (Exhibit 2-52). Over the past 650,000
years, CO2 concentrations have generally cycled over
several-thousand-year periods from highs around 285-300
parts per million (ppm) to lows around 180-185 ppm. From
at least 900 A.D. to 1800 A.D., CO2 concentrations stayed
relatively constant at about 270-290 ppm (panel B). Over
the past 150 years, CO2 concentrations increased steadily
from approximately 270-290 ppm in pre-industrial times
to 382 ppm in 2006, a 36 percent increase (panels B and
C). Almost all of this increase is due to human activities
(IPCC, 2007), and the concentrations measured currently
are the highest observed over the entire period of record.
2-68
EPA's 2008 Report on the Environment
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INDICATOI
Atmospheric Concentrations of Greenhouse Gases (continued)
Exhibit 2-54. Global atmospheric concentrations of nitrous oxide (N2O) over geological time and in
recent years
350
325
S 300
o.
o.
o
cs
8
§ 225
O
z 200
<:
0
"1 £U,'
A. 104,301
.
f\\ \U|
» B
1
^
BC to 1871 AD
/i
1
1
4?
F
Illl
1 "
1 II
11
HI
<
B. 9000 BC to 1976 AD
'
VvAvvA^y/iN^V^^^r
>
-
C. 1978 AD to 2006 AD
I
>
00-100,000-75,000-50,000-25,000 0 25,000 -10000-8000 -6000 -4000 -2000 0 2000 1975 1980 1985 1990 1995 2000 2005
Year (negative values = BC)
Trend lines and data sources:
104,301 BC to 1871 AD 9000 BC to 1976 AD 1978 AD to 2006 AD
- Greenland GISP2 ice core (Sowers et - EPICA Dome C, Antarctica (Fluckiger Barrow, Alaska (NOAA-ESRL, 2007d)
al" 2003) et al" 2002) - Cape Grim, Australia (AGAGE, 2007)
Taylor Dome, Antarctica (Sowers et Antarctica (Machida eta/., 1995) Mauna Loa Hawaii (NOAA-ESRL
al; 2003) - Antarctica (Battle etal., 1996) - 2007d)
South Pole, USA station (NOAA-ESRL,
20076)
CH4 concentrations also cycled widely over the past
650,000 years, but peaks remained below 800 parts per
billion (ppb) until after 1800 A.D. (Exhibit 2-53). Con-
centrations slightly increased between 1000 A.D. and 1730
A.D. (panel B). It then took approximately 175 years (c.
1905) to add 200 ppb to atmospheric CH4 concentrations,
approximately 40 years (c. 1945) to add the next 200 ppb,
approximately 20 years (c. 1965) to add the next 200 ppb,
and approximately 10 years (c. 1975) to add the next 200
ppb (panel B). In 2006, CH4 concentrations at the two
stations considered were 1,727 ppb and 1,788 ppb (panel
C), and these current levels far exceed the natural range
surmised from the ice core samples. The rates of CH4 con-
centration increase began to slow by the late 1970s, with
approximately 300 ppb added to atmospheric concentrations
between 1978 and 2006 (panels B and C). Overall, global
CH4 concentrations have more than doubled in the past 150
years. The most recent data show a significant difference
in CH4 concentrations across latitudes—a pattern of peak
concentrations in the most northern latitudes decreasing
toward the southern latitudes, suggesting net sources of CH4
in northern latitudes. Yet, despite the latitudinal differences
in concentrations, the pattern over the past two centuries
shows a common trend in all locations.
N2O concentrations (Exhibit 2-54) vacillated widely
through geological time, with ice sample measurements
ranging from as low as 180 ppb to above 280 ppb. Despite
considerable inter-decadal variability, N2O stayed mostly
below 280 ppb from 1756 A.D. until the 1920s (panel B),
from which point levels began to rise rapidly to approxi-
mately 320 ppb in 2006 (panels B and C), the highest level
recorded over the more than 100,000 years of data available.
Concentrations of the halocarbons (or gases that contain the
halogens chlorine, fluorine, bromine, or iodine) were essen-
tially zero a few decades ago, but have increased rapidly as
they were incorporated into industrial products and processes
(Exhibit 2-55). Concentrations of hydrochlorofluorocarbons
HCFC-141b and HCFC-142b increased through 2006, but
EPA's 2008 Report on the Environment
2-69
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INDICATOR
Atmospheric Concentrations of Greenhouse Gases (continued)
Exhibit 2-55. Global atmospheric concentrations
of selected halocarbons, 1978-20063
1,000-q
HCFC-22
1975 1980 1985 1990 1995 2000 2005
Year
aTrends are presented for hydrochlorofluorocarbons (HCFCs) and
hydrofluorocarbons (MFCs) with sufficient data to support
long-term trend analysis.
Data source: IPCC, 2007
are expected to gradually stabilize over this decade as they are
phased out in industrialized countries as part of the Montreal
Protocol on Substances That Deplete the Ozone Layer. The
concentration of HFC-23, which is a byproduct of HCFC-22
production, has increased more than five-fold between 1978
and 2006. Halocarbons that are not controlled by the Mon-
treal Protocol (because they do not contribute to stratospheric
ozone losses) mostly continued to increase because of their
•widespread use as substitutes for the Montreal Protocol gases.
Indicator Limitations
• Water vapor is not tracked in this indicator, as it is gener-
ally accepted that human activities have not increased the
concentration of water vapor in the atmosphere.
• Some radiatively important atmospheric constituents that
are substantially affected by human activities (such as tro-
pospheric ozone, black carbon, aerosols, and sulfates) are
not included in this indicator because of their spatial and
temporal variability and the inadequacy of available data
to characterize long-term averages or trends.
• Concentration data are not available for all the haloge-
nated compounds that are potentially important GHGs.
For instance, global concentration data are not sufficient
yet to track trends in concentrations of SF6 and PFCs.
• Ice core measurements are not taken in real time, which
introduces some error into the date of the sample. Dating
accuracy for the ice cores ranged up to +20 years (often
less), depending on the method used and the time period
of the sample. Diffusion of gases from the samples, which
•would tend to reduce the measured values, may also add
a small amount of uncertainty. More information on the
accuracy of measurements of ice samples and other mea-
surement methods can be found at http://cdiac.esd.ornl.
gov/by_new/bysubjec.html#atmospheric.
Data Sources
The data in this indicator come from multiple sources.
Summary global atmospheric concentration data for CO2
(Exhibit 2-52), CH4 (Exhibit 2-53), and N2O (Exhibit 2-54)
•were provided by EPA's Office of Atmospheric Programs,
based on GHG concentration measurements reported in a
collection of studies published in the peer-reviewed litera-
ture. References for the underlying data are included in the
corresponding exhibits, and some data sets are also available
in electronic format at http://www.epa.gov/climatechange/
science/recentac.html.
Summary global atmospheric concentration data for
selected halocarbons (Exhibit 2-55) are a subset of the data
depicted in IPCC's Fourth Assessment Report (IPCC, 2007).
References
AGAGE (Advanced Global Atmospheric Gases Experi-
ment). 2007. Monthly mean N2O concentrations for Cape
Grim, Australia. Accessed 2007.
Archer, D., and A. Ganopolski. 2005. A movable trig-
ger: Fossil fuel CO2 and the onset of the next glaciation.
Geochem. Geophys. Geosys. 6(Q05003).
Archer, D., H. Kheshgi, andE. Maier-Reimer. 1998.
Dynamics of fossil fuel neutralization by Marine CaCOr
Global Biogeochem. Cycles 12:259-276.
Barnola, J.M., D. Raynaud, C. Lorms, and N.I. Barkov. 2003.
Historical CO2 record from the Vostok ice core. In Trends: A
compendium of data on global change. Oak Ridge, TN: U.S.
Department of Energy,
Battle, M., M. Bender, T Sowers, P. Tans, J. Butler,]. Elkins,
J. Ellis, T. Conway, N. Zhang, P. Lang, and A. Clarke. 1996.
Histories of atmospheric gases from firn at the South Pole.
Nature 383:231-235.
Blunier, T, andEJ. Brook. 2001. Timing ofmillenial-scale
climate change in Antarctica and Greenland during the last
glacial period. Science 291:109-112.
Chamard, P., L. Ciattaglia, A. di Sarra, and F. Monteleone.
2001. Atmospheric CO record from flask measurements
at Lampedusa Island. In Trends: A compendium of data on
global change. Oak Ridge, TN: U.S. Department of Energy.
2-70
EPA's 2008 Report on the Environment
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INDICATOI
Atmospheric Concentrations of Greenhouse Gases (continued)
den Elzen, M., J. Fuglestvedt, N. Hohne, C. Trudinger, J.
Lowe, B. Matthewso, B. Romstadv, C. Pires de Campos,
and N. Andronova. 2005. Analysing countries' contri-
bution to climate change: Scientific and policy-related
choices. Env. Sci. Policy 8(6):614-636.
Etheridge, D.M., L.P. Steele, R.J. Francey, and R.L. Lan-
genfelds. 2002. Historical CH4 records since about 1000
A.D. from ice core data. In Trends: A compendium of
data on global change. Oak Ridge, TN: U.S. Department
of Energy.
Etheridge, D.M., L.P. Steele, R.L. Langenfelds, R.I.
O ' O J
Francey, J.M. Barnola, and V.I. Morgan. 1998. Histori-
cal CO2 records from the Law Dome DE08, DE08-2, and
DSS ice cores. In Trends: A compendium of data on global
change. Oak Ridge, TN: U.S. Department of Energy.
Fliickiger, J., E. Monnin, B. Stauffer, J. Schwander, T.F.
Stocker, J. Chappellaz, D. Raynaud, and J.M. Barnola.
2002. High resolution Holocene N2O ice core record and
its relationship with CH4 and CO2. Global Biogeochem.
Cycles 16(1):1010.
IPCC (Intergovernmental Panel on Climate Change). 2007.
Climate change 2007: The physical science basis (fourth assess-
ment report). Cambridge, UK: Cambridge University Press.
IPCC (Intergovernmental Panel on Climate Change). 2001.
Climate change 2001: The scientific basis (third assessment
report). Cambridge, UK: Cambridge University Press.
Machida, T., T. Nakazawa, Y. Fujii, S. Aoki, and O.
Watanabe. 1995. Increase in atmospheric nitrous oxide
concentration during the last 250 years. Geophys. Res.
Lett. 22(21):2921-2924.
Neftel, A., H. Friedli, E. Moor, H. Lotscher, H. Oeschger,
U Siegenthaler, and B. Stauffer. 1994. Historical CO2 record
from the Siple Station ice core. In Trends: A compendium of
data on global change. Oak Ridge, TN: U.S. Department of
Energy,
NOAA-ESRL (National Oceanic and Atmospheric
Administration, Earth System Research Laboratory). 2007a.
Monthly mean CO2 concentrations for Mauna Loa, Hawaii.
Accessed 2007.
NOAA-ESRL (National Oceanic and Atmospheric
Administration, Earth System Research Laboratory).
2007b. Monthly mean CH4 concentrations for Cape Grim,
Australia. Accessed 2007.
NOAA-ESRL (National Oceanic and Atmospheric
Administration, Earth System Research Laboratory).
2007c. Monthly mean CH4 concentrations for Mauna Loa,
Hawaii. Accessed 2007.
NOAA-ESRL (National Oceanic and Atmospheric
Administration, Earth System Research Laboratory).
2007d. Monthly mean N2O concentrations for Barrow,
Alaska, Mauna Loa, Hawaii, and the South Pole. Accessed
2007.
Petit, J.R.J. Jouzel, D. Raynaud, N.I. Barkov, J.M.
Barnola, I. Basile, M. Bender, J. Chappellaz, J. Davis, G.
Delaygue, M. Delmotte, V.M. Kotlyakov, M. Legrand, V.
Lipenkov, C. Lorius, L. Pepin, C. Ritz, E. Saltzman, and
M. Stievenard. 1999. Climate and atmospheric history of
the past 420,000 years from the Vostok Ice Core, Antarc-
tica. Nature 399:429-436.
Siegenthaler, U, T. F. Stocker, E. Monnin, D. Liithi, J.
Schwander, B. Stauffer, D. Raynaud, J.M. Barnola, H.
Fischer, V. Masson-Delmotte, and J. Jouzel. 2005. Stable
carbon cycle-climate relationship during the late pleisto-
cene. Science 310:1313-1317.
Sowers, T, R.B. Alley, andj. Jubenville. 2003. Ice core
records of atmospheric NO covering the last 106,000
years. Science 301(5635):945-948.
Spahni, R., J. Chappellaz, T.F. Stocker, L. Loulergue, G.
Hausammann, K. Kawamura, J. Fliickiger, J. Schwander,
D. Raynaud, V. Masson-Delmotte, and J. Jouzel. 2005.
Atmospheric methane and nitrous oxide of the late Pleisto-
cene from Antarctic ice cores. Science 310:1317-1321.
Steele, L.P., P.B. Krummel, and R.L. Langenfelds. 2002.
Atmospheric CO2 and CH4 concentrations from sites in
the CSIRO Atmospheric Research GASLAB air sampling
net-work (October 2002 version). In Trends: A compen-
dium of data on global change. Oak Ridge, TN: U.S.
Department of Energy,
Thonmg, K.W., and P.P. Tans. 2000. Atmospheric CO2
records from sites in the NOAA/CMDL continuous moni-
toring net-work. In Trends: A compendium of data on global
change. Oak Ridge, TN: U.S. Department of Energy.
WDCGG (World Data Centre for Greenhouse Gases).
2005. Atmospheric CH4 concentrations for Greenland Site
J. Accessed 2005.
EPA's 2008 Report on the Environment
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2.3.3 Discussion
What These Indicators Say About Trends
in Greenhouse Gas Emissions and
Concentrations
For several greenhouse gases, the nation's estimated combined
emissions that are directly attributable to human activity have
increased 16 percent between 1990 and 2005 (the U.S. Green-
house Gas Emissions indicator, p. 2-64). Emissions sources
occur in several sectors of the U.S. economy, with the highest
contribution—and the greatest recent growth—attributed to
energy use, primarily electricity generation and transporta-
tion. As well as detailing the increase, the U.S. Greenhouse
Gas Emissions indicator compares contributions of different
greenhouse gases by normalizing for each gas's ability to affect
the Earth's energy balance. The results show that carbon diox-
ide (CO2) makes up the bulk of the nation's anthropogenic
greenhouse gas emissions. Both observations demonstrate that
fossil fuel combustion is clearly the country's major source of
anthropogenic greenhouse gas emissions.
Data on atmospheric concentrations of greenhouse gases have
extraordinary temporal coverage (the Greenhouse Gas Con-
centrations indicator, p. 2-66). For CO2, methane (CH4), and
nitrous oxide (NO), concentration data span several hundred
thousand years; and for selected halocarbons, concentration
data span virtually the entire period during which these syn-
thetic gases were widely used. Thus, these concentration data
provide an excellent basis for answering the question regard-
ing trends in greenhouse gas concentrations. The historical
data for CO2, CH4, and N2O show considerable temporal
variability in these gases' concentrations; however, concentra-
tions observed in the past 50 years are higher than those over
the entire period of record evaluated—even when considering
natural fluctuations. In short, the historical context provided
by ice cores shows that present concentrations of these three
greenhouse gases are unprecedented over the last 650,000
years, and demonstrate that the recently increasing levels
reflect the influence of human activity. For the various halo-
carbons considered, concentrations have increased between
1980 and 2006, with some increases spanning more than two
orders of magnitude, but the rate at which these concentra-
tions is increasing has slowed in recent years.
Taken together, the well-documented long-term trends in
concentrations of greenhouse gases, along with corresponding
increases in emissions from anthropogenic sources, show that
human activity is causing increased concentrations of green-
house gases in the Earth's atmosphere—a finding echoed in
many prominent reviews on the science of climate change.25'26
Limitations, Gaps, and Challenges
Although they provide extensive insights into greenhouse
gas emissions and concentrations, the two greenhouse gas
indicators have limitations and gaps that should be acknowl-
edged. The emissions trends, for instance, are based largely on
estimates, which have uncertainties inherent in the engineer-
ing calculations and estimation methodologies developed for
the U.S. greenhouse gas emissions inventory. Uncertainty of
the magnitude of the emissions varies among the gases and
sources, though estimated emissions from some of the larg-
est sources (e.g., CO2 emissions from fossil fuel combustion)
are considered highly accurate.27 One gap in the emissions
indicator is that EPA's greenhouse gas inventory does not track
every greenhouse gas or every emissions source. Examples
of greenhouse gases not included in the inventory are ozone
and selected chlorofluorocarbons. The most notable sources
not tracked in the inventory are natural sources, such as CH4
from wetlands, CO2 and CH4 from thawing permafrost,
and multiple emissions from volcanoes. Though this is not
necessarily a limitation or a gap, it is important to note that
EPA's greenhouse gas inventory, by design, tracks only this
nation's anthropogenic emissions of greenhouse gases.28 For
perspective on how the nation's emissions compare to those
from other countries, recent data estimate that the U.S. emits
approximately 20 percent of the total worldwide amounts of
selected greenhouse gases. Having national emissions indica-
tors on a more complete set of greenhouse gases and emissions
sources would further improve EPA's ability to track pressures
that affect climate change.
The Greenhouse Gas Concentrations indicator (p. 2-66) tracks
trends in measured airborne levels of greenhouse gases regard-
less of the anthropogenic or natural sources that released them,
•which helps account for some of the inherent limitations and
uncertainties in the emissions indicator. However, the concen-
tration data have limitations and gaps of their own. Historical
concentrations from ice core samples are not measured in real
time, which introduces some minor uncertainty into the data
set; consistency among measurements made by multiple labora-
tories at different locations suggests this uncertainty is relatively
low.29 While the concentration data thoroughly characterize
trends for CO2 (the most important anthropogenic greenhouse
gas) and other extensively studied gases, a gap in the concentra-
tion data, as with the emissions data, is that not all greenhouse
gases have been monitored. Long-term trend data for ozone,
for instance, are currently not available. Measuring globally
representative trends in tropospheric ozone concentrations
presents technical challenges, because ozone is a short-lived gas
(which does not lend well to ice core measurements) with con-
centrations that exhibit tremendous spatial variations (which
•would require extensive monitoring to characterize worldwide
National Research Council. 2001. Climate change science: An analysis of
some key questions.Washington, DC: National Academy Press.
Intergovernmental Panel on Climate Change. 2007. Climate change 2007:
The scientific basis (fourth assessment report). Cambridge, UK: Cambridge
University Press.
U.S. Environmental Protection Agency. 2007. Inventory of U.S. greenhouse
gas emissions and sinks: 1990-2005. EPA/430/R-07/002. Washington, DC.
den Elzen, M.J. Fuglestvedt, N. Hohne, C.Trudinger, J. Lowe, B. Matthews, B.
Romstad, C. Pires de Campos, and NAndronova. 2005.Analysing countries'
contribution to climate change: Scientific and policy-related choices. Env. Sci.
Policy 8(6):614-636.
BarnolaJ., D. Raynaud, C. Lorius, and N.I. Barkov. 2003. Historical CO2
record from theVostok ice core. In:Trends:A compendium of data on global
change. Oak Ridge,TN: US. Department of Energy.
2-72
EPA's 2008 Report on the Environment
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trends). Another gap is the lack of ROE indicators for radia-
tively important substances, such as soot and aerosols. Though
these substances technically are not greenhouse gases, tracking
trends in these substances' concentrations is important due to
their ability to alter the Earth's energy balance.
2.4 What Are the Trends
in Indoor Air Quality
and Their Effects on
Human Health?
2.4.1 Introduction
"Indoor air quality" refers to the quality of the air in a home,
school, office, or other building environment. Most pollutants
affecting indoor air quality come from sources inside build-
ings, although some originate outdoors. Typical pollutants of
concern include combustion products such as carbon mon-
oxide, particulate matter, and environmental tobacco smoke;
substances of natural origin such as radon; biological agents
such as molds; pesticides; lead; asbestos; ozone (from some
air cleaners); and various volatile organic compounds from a
variety of products and materials. Indoor concentrations of
some pollutants have increased in recent decades due to such
factors as energy-efficient building construction and increased
use of synthetic building materials, furnishings, personal care
products, pesticides, and household cleaners.
The potential impact of indoor air quality on human health
nationally is considerable, for several reasons. Americans,
on average, spend approximately 90 percent of their time
indoors,30 where the concentrations of some pollutants are
often 2 to 5 times higher than typical outdoor concentra-
tions.31 Moreover, people who are often most susceptible to
the adverse effects of pollution (e.g., the very young, older
adults, people with cardiovascular or respiratory disease) tend
to spend even more time indoors.32 Health effects that have
been associated with indoor air pollutants include irritation of
the eyes, nose, and throat; headaches, dizziness, and fatigue;
respiratory diseases; heart disease; and cancer.
Indoor air pollutants originate from many sources. These
sources can be classified into two general categories:
• Indoor sources (sources within buildings themselves).
Combustion sources in indoor settings, including tobacco,
heating and cooking appliances, and fireplaces, can release
harmful combustion byproducts such as carbon monoxide
U.S. Environmental Protection Agency. 1989. Report to Congress on indoor
air quality:Volume 2. EPA/400/1-89/001C. Washington, DC.
U.S. Environmental Protection Agency. 1987.The total exposure assessment
methodology (TEAM) study: summary and analysis. EPA/600/6-87/002a.
Washington, DC.
U.S. Environmental Protection Agency. 1997. Exposure factors handbook:
volume 3—activity factors. EPA/600/P-95/002Fa.Washington, DC.
and particulate matter directly into the indoor environment.
Cleaning supplies, paints, insecticides, and other commonly
used products introduce many different chemicals, includ-
ing volatile organic compounds, directly into the indoor
air. Building materials are also potential sources, whether
through degrading materials (e.g., asbestos fibers released
from building insulation) or from new materials (e.g.,
chemical off-gassing from pressed wood products). Other
substances in indoor air are of natural origin, such as mold
and pet dander.
• Outdoor sources. Outdoor air pollutants can enter build-
ings through open doors, open windows, ventilation systems,
and cracks in structures. Some pollutants come indoors
through building foundations. For instance, radon forms in
the ground as naturally occurring uranium in rocks and soils
decays. The radon can then enter buildings through cracks
or gaps in structures. In areas with contaminated ground
•water or soils, volatile chemicals can enter buildings through
this same process. Volatile chemicals in water supplies can
also enter indoor air when building occupants use the water
(e.g., during showering, cooking). Finally, when people enter
buildings, they can inadvertently bring in soils and dusts on
their shoes and clothing from the outdoors, along with pol-
lutants that adhere to those particles.
In addition to pollutant sources, the air exchange rate with the
outdoors is an important factor in determining indoor air pol-
lutant concentrations. The air exchange rate is affected by the
design, construction, and operating parameters of buildings and
is ultimately a function of infiltration (air that flows into struc-
tures through openings, joints, and cracks in walls, floors, and
ceilings and around windows and doors), natural ventilation (air
that flows through opened windows and doors), and mechani-
cal ventilation (air that is forced indoors or vented outdoors by
ventilation devices, such as fans or air handling systems). Out-
door climate and weather conditions combined with occupant
behavior can also affect indoor air quality. Weather conditions
influence whether building occupants keep windows open or
closed and whether they operate air conditioners, humidifiers,
or heaters, all of which can impact indoor air quality. Weather
also has a large effect on infiltration. Certain climatic conditions
can increase the potential for indoor moisture and mold growth
if not controlled by adequate ventilation or air conditioning.
The link between some common indoor air pollutants and
health effects is very well established. Radon is a known
human carcinogen and is the second leading cause of lung
cancer.33'34 Carbon monoxide is toxic, and short-term expo-
sure to elevated carbon monoxide levels in indoor settings
can be lethal.35 Episodes of Legionnaires' disease, a form of
pneumonia caused by exposure to the Legionella bacterium,
have been associated with buildings with poorly maintained
air conditioning or heating systems.36'37 In addition, numerous
33 U.S. Environmental Protection Agency. 2003. EPA assessment of risks from
radon in homes. EPA/402/R-03/003.Washington, DC.
34 National Research Council. 1999. Health effects of exposure to indoor radon:
biological effects of ionizing radiation (BEIR), reportVI.Washington, DC:
National Academy Press,
35 Raub, J.A., M. Mathieu-Nolf, N.B. Hampson, S.R.Thorn. 2000. Carbon
monoxide poisoning—a public health perspective.Toxicology 145:1-14.
EPA's 2008 Report on the Environment
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indoor air pollutants—dust mites, mold, pet dander, environ-
mental tobacco smoke, cockroach allergens, and others—are
"asthma triggers," meaning that some asthmatics might expe-
rience asthma attacks following exposure.38
While these and other adverse health effects have been
attributed to specific pollutants, the scientific understanding
of some indoor air quality issues continues to evolve. One
example is "sick building syndrome," which occurs when
building occupants experience similar symptoms after enter-
ing a particular building, with symptoms diminishing or
disappearing after they leave the building; these symptoms are
increasingly being attributed to a variety of building indoor
air attributes.
Researchers also have been investigating the relationship
between indoor air quality and important issues not nec-
essarily related to health, such as student performance in
the classroom and productivity in occupational settings.39
Another evolving area is research in "green building" design,
construction, operation, and maintenance that achieves energy
efficiency and enhances indoor air quality.
2.4.2 ROE Indicators
Two National Indicators that fully meet the indicator criteria
are discussed in this section. These indicators address two spe-
cific issues and do not cover the wide range of issues associated
•with indoor air quality. The two indicators focus on radon
and environmental tobacco smoke. The indicator on radon
levels in homes is based on EPA's 1992 National Residential
Radon Survey, 2000 U.S. Census data, and production and
sales statistics for radon mitigation systems. Environmental
tobacco smoke is addressed using biomarker data for cotinine,
a metabolite linked exclusively to chemicals found in tobacco
smoke. The Centers for Disease Control and Prevention have
reported these biomarker data in multiple releases of their
National Health and Nutrition Examination Survey.
Table 2-4. ROE Indicators of Trends in Indoor Air Quality and Their Effects
on Human Health
National Indicators
U.S. Homes Above EPA's Radon Action Level
Blood Cotinine Level
Section
2.4.2
2.4.2
2-74
2-76
INDICATOR
U.S. Homes Above EPA's Radon Action Level
Radon is a radioactive gas. It comes from the decay of
uranium that is naturally occurring and commonly
present in rock and soils. It typically moves up through the
ground to the air above and into a home through path-ways
in ground contact floors and walls. Picocuries per liter of
air (pCi/L) is the unit of measure for radon in air (the met-
ric equivalent is becquerels per cubic meter of air).
Each year, radon is associated with an estimated 21,100
lung cancer deaths in the U.S., with smokers at an increased
risk; radon is the second leading cause of lung cancer after
smoking, and 14.4 percent of lung cancer deaths in the
U.S. are believed to be radon-related (U.S. EPA, 2003). To
reduce the risk of lung cancer, EPA has set a recommended
"action level" of 4 pCi/L for homes. At that level, it is cost-
effective for occupants to reduce their exposure by imple-
menting preventive measures in their homes.
This indicator presents (1) the number of U.S. homes
estimated to be at or above the EPA recommended radon
action level of 4 pCi/L and (2) the number of homes with
an operating radon mitigation system. The gap between
the homes in these two categories is the number of homes
that have not yet been mitigated (generally, homes are only
mitigated if the EPA recommended radon action level of
4 pCi/L or more is measured). The data for this indicator
•were extracted from the National Residential Radon Sur-
vey (U.S. EPA, 1992a), \vhich estimated radon levels in the
U.S. housing stock. The number of homes at or above 4
pCi/L \vas estimated by applying the results of the Radon
Survey (U.S. EPA, 1992a) to 2000 U.S. Census data
on the number of U.S. households. The 1992 National
Residential Radon Survey was based on the housing
stock that \vould be covered by EPA's radon testing policy
(i.e., homes that should test). This included only homes
Allan, T., et al. 2001. Outbreak of Legionnaires' disease among automotive
plant workers—Ohio, 2001. MMWR 50(18):357-359.
Fields, B.S., R.E Benson, and R.E. Besser. 2002. Legionella and Legionnaires'
disease: 25 years of investigation. Clin. Microbiol. Rev. 15(3):506-526.
Institute of Medicine. 2000. Clearing the air: Asthma and indoor air expo-
sures.Washington, DC: National Academy Press.
U.S. Environmental Protection Agency 2003. Indoor air quality and student
performance. EPA/402/K-03/006. Washington, DC.
2-74
EPA's 2008 Report on the Environment
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INDICATOI
U.S. Homes Above EPA's Radon Action Level (continued)
intended for regular (year-round) use but covers single-
family homes, mobile homes, and multi-unit and group
quarters (U.S. EPA, 1992b). The 1992 residential survey
estimated that about one in 15 homes in EPA's "should
test" category would have a radon level of 4 pCi/L or
more. The measure of the number of homes with operat-
ing mitigation systems was developed from radon vent fan
sales data provided voluntarily by fan manufacturers.
What the Data Show
There was a 308 percent increase in the number of homes
•with operating mitigation systems from 1990 to 2006,
going from 175,000 to 714,000 homes over 17 years;
but during the same period, there has been a 22 percent
increase in the estimated number of homes with radon
levels at or above 4 pCi/L, from about 6.4 million to 7.8
million homes (Exhibit 2-56, panel A). Panel B of Exhibit
2-56 shows radon potential in homes at the county level
based on indoor radon measurements, geology, aerial
radioactivity, soil permeability, and foundation type.
Zone 1 is the highest radon potential area, followed by
Zone 2 (medium), and Zone 3 (low).
It has been reported anecdotally that radon vent fans
and mitigation systems are also being used to control for
soil gases and vapor intrusion in homes in the vicinity
of Superfund sites, underground or aboveground stor-
age tank sites, and similar sites as an element of corrective
action plans. While radon vent fans and mitigation systems
used in this way may provide a radon reduction benefit,
they could be considered a subtraction from the number
of homes with operating mitigation systems, thus slightly
reducing the slope of the trend line.
Indicator Limitations
• The indicator presumes that radon vent fans are used for
their intended purpose; the available information supports
this premise. Even if fans are used for managing vapor
intrusion, a radon risk reduction benefit still occurs.
• A home with an operating mitigation system is presumed
to have a vent fan with an average useful life of 10 years.
Each year the total number of homes with operating
mitigation systems is adjusted to reflect new additions
and subtractions (i.e., vent fans installed 11 years earlier).
• The number of homes with radon levels at or above 4
pCi/L is an estimate based on one year of measurement
data extrapolated for subsequent years based on popula-
tion data, rather than on continuing measurements.
• This indicator does not track the number of homes
designed and built with radon-resistant new construction
features, which can help diminish radon entry in homes.
Thus, more people are likely being protected from
elevated indoor air exposures to radon than suggested by
the trends in operating radon mitigation systems alone.
Exhibit 2-56. Homes at or above EPA's radon
action level and homes with operating mitigation
systems in the U.S., 1990-2006
A. Trend data
7
6
^ 5
.°
1 4
&
o
E 3
o
x:
2
1
0
___
Hor
md
abo
nes with estimated radon
Dor air concentrations at or
ve 4 pCi/L
Homes with radon
mitigation systems
•
- -
'90 '92 '94 '96 '98 '00 '02 '04 '06
Year
B. EPA map of radon zones
preliminary
zone designation
• Zone 1: Counties with predicted average indoor radon
screening levels greater than 4 pCi/L
• Zone 2: Counties with predicted average indoor radon
screening levels from 2 to 4 pCi/L
d Zone 3: Counties with predicted average indoor radon
screening levels less than 2 pCi/L
Data source: U.S. EPA, 1992a, 2007
Data Sources
Summary data in this indicator were provided by EPA's
Office of Radiation and Indoor Air, based on two types of
information. The number of homes with estimated indoor
air concentrations at or above EPA's radon action level was
originally derived from the National Residential Radon
Survey (U.S. EPA, 1992a) and is updated with U.S. Census
EPA's 2008 Report on the Environment
2-75
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INDICATOR
U.S. Homes Above EPA's Radon Action Level (continued)
data; and the number of homes with radon mitigation sys-
tems was developed from unpublished sales data provided
by radon vent fan manufacturers (U.S. EPA, 2007).
References
U.S. EPA, 2007. Unpublished sales data provided by radon
vent manufacturers.
U.S. EPA. 2003. EPA assessment of risks from radon in
homes. EPA/402/R-03/003. Washington, DC.
U.S. EPA. 1992a. National residential radon survey:
Summary report. EPA/402/R-92/011.
Washington, DC. October.
U.S. EPA. 1992b. Technical support document.
EPA/400/R-92/011.
INDICATOR
Blood Cotinine Level
Environmental tobacco smoke (ETS) contains a mixture
of toxic chemicals, including known human carcino-
gens. Persistent exposure to ETS is associated with numer-
ous health-related disorders or symptoms, such as coughing,
chest discomfort, reduced lung function, acute and chronic
coronary heart disease, and lung cancer (IARC, 2004;
NTP, 2002; U.S. EPA, 1992; CDC, 2005). Children are at
particular risk from exposure to ETS, which can exacerbate
existing asthma among susceptible children and also greatly
increase the risk for lower respiratory tract illness, such as
bronchitis and pneumonia, among younger children (CDC,
2005). Younger children appear to be more susceptible to
the effects of ETS than are older children (U.S. EPA, 1992).
Household ETS exposure is an important issue because
many people, especially young children, spend much time
inside their homes. Based on data reported from the 1994
National Health Interview Survey, the Department of
Health and Human Services estimates that 27 percent of
children age 6 years and younger are exposed to ETS in
the home (U.S. DHHS, 2000).
Exposure to ETS leaves traces of specific chemicals in
people's blood, urine, saliva, and hair. Cotinine is a chemical
that forms inside the body following exposure to nicotine,
an ingredient in all tobacco products and a component of
ETS. Following nicotine exposures, cotinine can usually
be detected in blood for at least 1 or 2 days (Pirkle et al.,
1996). Active smokers almost always have blood cotinine
levels higher than 10 nanograms per milliliter (ng/mL),
•while non-smokers exposed to low levels of ETS typically
have blood concentrations less than 1 ng/mL (CDC, 2005).
Following heavy exposure to ETS, non-smokers can have
blood cotinine levels between 1 and 10 ng/mL.
This indicator reflects blood cotinine concentrations
in ng/mL among non-smokers for the U.S. population,
age 3 years and older, as measured in the 1999-2000 and
2001-2002 National Health and Nutrition Examination
Survey (NHANES). NHANES is a series of surveys con-
ducted by the Centers for Disease Control and Prevention's
(CDC's) National Center for Health Statistics, designed
to collect data on the health and nutritional status of the
civilian, non-institutionalized U.S. population using a
complex, stratified, multistage, probability-cluster design.
Blood cotinine also was monitored in non-smokers age 4
years and older as part of NHANES III, between 1988 and
1991. CDC's National Center for Environmental Health
conducted the laboratory analyses for the biomonitoring
samples. Beginning in 1999, NHANES became a continu-
ous and annual national survey.
What the Data Show
As part of NHANES III (1988-1991), CDC estimated
that the median blood serum level (50th percentile) of
cotinine among non-smokers in the general U.S. population
was 0.20 ng/mL. In NHANES 1999-2000, the estimated
median serum level among non-smokers nation-wide was
0.06 ng/mL. During the 2001-2002 survey, the estimated
blood cotinine levels for the U.S. population were very
similar to 1999-2000, \vith the median concentration actu-
ally below the limit of detection, and the geometric mean
0.06 ng/mL (see Exhibit 2-57). This marks a 70 percent
decrease from levels measured in the 1988-1991 NHANES
III survey—a reduction that suggests a marked decrease in
exposure to ETS.
Exhibit 2-57 also shows the results of the NHANES
1999-2000 and 2001-2002 survey, for different subpopu-
lations. Similar decreasing trends in blood cotinine levels
between NHANES III (1988-1991) and the most recent
2001-2002 survey \vere observed in each of the popula-
tion groups defined by age, sex, and race/ethnicity (CDC,
2005). These data reveal three additional observations:
(1) non-smoking males have higher cotinine levels than
non-smoking females; (2) of the ethnic groups presented,
2-76
EPA's 2008 Report on the Environment
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INDICATOI
Blood Cotinine Level (continued)
Exhibit 2-57. Blood cotinine concentrations for the
selected demographic groups, 1999-2002
non-smoking U.S. population age 3 years and older by
Geometric mean and selected percentiles
for blood cotinine concentrations (ng/ml_)a D c
Total, age 3 years
and older
Sex
Male
Female
Race and ethnicity
Survey years
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
Black, non-Hiscanic •
2001-2002
1999-2000
Mexican American
2001-2002
1999-2000
White, non-Hispanic •
Age group
3-11 years
12-19 years
20+ years
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
Sample size
5,999
6,813
2,789
3,149
3,210
3,664
1,333
1,599
2,241
1,877
1,950
2,845
1,174
1,414
1,773
1,902
3,052
3,497
Geometric mean
NC
0.06
NC
0.08
NC
0.05
NC
0.16
NC
0.06
NC
0.05
NC
0.11
NC
0.09
NC
0.05
a NC = not calculated; the proportion of results below the limit of detection was too high to
b
-------
INDICATOI
Blood Cotinine Level (continued)
100
90
80
| 70
•o
S 60
o
•S 50
S 40
o
£ 30
20
10
0
necessarily reflect a trend. Earlier data
sets are available (e.g., NHANES III), but
the data are not directly comparable to
NHANES 1999-2002. As CDC releases
additional survey results (e.g., 2003-2004),
it will become possible to more fully evalu-
ate trends (CDC, 2002, 2004).
Data Sources
Data used for this indicator were extracted
from two reports that present results of
the ongoing NHANES: the data shown in
Exhibit 2-57 were obtained from a CDC
report (2005), and the data shown in Exhibit
2-58 were obtained from a report by the
Federal Interagency Forum on Child and
Family Statistics (2005). The underlying
laboratory data supporting both reports are
available online in SAS® transport file formats
at http://www.cdc.gov/nchs/about/major/
nhanes/datalink.htm.
References
CDC (Centers for Disease Control and
Prevention). 2005. Third national report on
human exposure to environmental chemicals.
NCEH Pub. No. 05-0570. July. Accessed
September 9, 2005.
CDC. 2004. NHANES analytic guidelines. June 2004 ver-
sion. Accessed October 21, 2005.
CDC. 2002. NHANES 1999-2000 addendum to the
NHANES III analytic guidelines. Last update August 30,
2002. Accessed October 11, 2005.
Federal Interagency Forum on Child and Family Statistics.
2007. America's children: Key national indicators of-well-
being, 2007. Washington, DC: U.S. Government Printing
Office. Accessed October 2007.
Federal Interagency Forum on Child and Family Statistics.
2005. America's children: Key national indicators of-well-
being, 2005. Washington, DC: U.S. Government Printing
Office. Accessed December 20, 2005.
Exhibit 2-58. Blood cotinine concentrations in U.S. children
age 4 to 17 by race and ethnicity, 1988-1994 and 1999-20023
Total Black,
non-Hispanic
63.7
23.7
Mexican
American
White,
non-Hispanic
41.0
16.5
57.9
36.6
59.4
22.4
72.8
10.7
41.3
5.2
62.5
24.2
35.5
19.1
8-'94 '99-'02
8-'94 '99-'02
8-'94 '99-'02
8-'94 '99-'02
Year
aCotinine concentrations are reported for non-smoking
children only.
Concentrations below 0.05 ng/mL are not presented
here because this was the detection limit for many of
the samples.
Data source: Federal Interagency Forum on Child and Family Statistics, 2005
Concentration:
• 0.05 to 1.0 ng/mL
D More than 1.0 ng/mL
IARC (International Agency for Research on Cancer).
2004. I ARC -working group on the evaluation of carci-
nogenic risks to humans. Evaluation of carcinogenic risks
to humans, volume 83: Tobacco smoke and involuntary
smoking. Lyon, France.
NTP (National Toxicology Program) 2002. Report on
carcinogens, 10th edition.
Pirkle, J.L., K.M. FlegalJ.T Bernert, DJ. Brody, R.A.
Etzel, K.R. Maurer. 1996. Exposure of the U.S. popula-
tion to environmental tobacco smoke: The third national
health and nutrition examination survey, 1988 to 1991. J.
Amer. Med. Assoc. 275:1233-1240.
U.S. DHHS (United States Department of Health and
Human Services). 2000. Healthy people 2010. Second edi-
tion. Washington, DC: U.S. Government Printing Office
U.S. EPA (United States Environmental Protection
Agency). 1992. Respiratory health effects of passive smok-
ing: Lung cancer and other disorders. Washington, DC.
2-78
EPA's 2008 Report on the Environment
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2.4.3 Discussion
What These Indicators Say About Trends
in Indoor Air Quality and Their Effects on
Human Health
The two indoor air quality indicators provide insights into
issues of very different origin: radon is a substance in indoor
air produced by a natural source, while environmental tobacco
smoke (as evaluated by the presence of blood cotinine) in
indoor environments is linked entirely to human behavior.
The Homes Above EPA's Radon Action Level indicator (p.
2-74) tracks two statistics: the number of homes estimated to
be at or above EPA's action level (4 pCi/L) for radon, and the
number of homes with operating radon mitigation systems.
Evaluating trends in radon mitigation systems is relevant
because properly operated systems are expected to reduce
radon to levels below the action level, and therefore also are
expected to reduce radon-related health risks among build-
ing occupants. Between 1990 and 2006, the number of homes
\vith radon mitigation systems increased more than four-fold,
but these homes account for less than 10 percent of the nation's
homes currently believed to have radon levels at or above
EPA's action level. Some residents are being protected against
radon exposures through radon-resistant new construction
techniques used when a home is built. Estimates of radon-
resistant new construction practices are not included in the
indicator, however, because while they substantially reduce
radon levels in homes with high radon potential, they do not
always reduce the levels below the action level.
The Blood Cotinine indicator (p. 2-76) tracks blood concen-
trations of cotinine, a metabolite of nicotine, and shows that
exposure to environmental tobacco smoke among non-smokers
decreased considerably in the last decade. This decrease was
observed for all population groups, defined by age (includ-
ing children), sex, and ethnicity. However, children's blood
cotinine levels, on average, are still more than twice the levels
observed in adults. A logical explanation for the downward
trend in blood cotinine levels is modified behavior, whether
reduced smoking prevalence or more -widespread restriction of
areas in which individuals are allowed to smoke.
Taken together, these indicators show that an increasing num-
ber of Americans have reduced indoor air exposures to two
known carcinogens. Though these improvements are encour-
aging, both radon and environmental tobacco smoke remain
important indoor air quality issues. In the case of radon, for
example, the increase in the number of homes estimated to
be at or above the EPA's radon action level is outpacing the
increase in the use of radon mitigation systems.
Limitations, Gaps, and Challenges
The two indicators in this section provide extensive, but not
comprehensive, information on the corresponding indoor air
quality issues that they characterize. An important limitation
of the Homes Above EPA's Radon Action Level indicator,
for instance, is that it does not track the number of homes
designed and built with radon-resistant new construction fea-
tures, \vhich can diminish radon entry in homes and therefore
reduce radon exposures and the associated lung cancer risk.
Thus, more people are likely being protected from elevated
indoor air exposures to radon than is suggested by trends in
radon mitigation systems alone.
The Blood Cotinine indicator also has certain limitations.
For example, exposure to environmental tobacco smoke
does not occur exclusively indoors: some proportion of blood
cotinine levels measured in non-smokers reflects exposures
that occurred outdoors. In addition, nationally representa-
tive blood cotinine data are not available for children under 3
years old—an age group -with documented susceptibilities to
environmental tobacco smoke.40 Nonetheless, none of these
limitations call into question this indicator's main finding:
nation-wide, exposures to environmental tobacco smoke
among non-smokers are decreasing. Moreover, reliable survey
data on smoking behavior corroborates this downward trend.41
The two indoor air quality indicators provide useful insights
into trends for radon and environmental tobacco smoke, but
they leave some gaps that EPA -would like to fill to better
answer the overarching question on nation-wide indoor air
quality trends and associated health effects. For example,
ROE indicators could not be developed for indoor air qual-
ity trends for molds, some combustion products, chemicals
found in common household cleaners and building materi-
als, and certain persistent pollutants and endocrine disrupters
that have been identified in household dust.42'43 There is no
quantitative, nationally representative inventory of emissions
sources in indoor environments, nor is there a nation-wide
monitoring net-work that routinely measures air quality inside
homes, schools, and office buildings. These gaps in nation-
wide indicators do not mean that nothing is known about the
broad range of indoor air quality issues and associated health
effects. Rather, information on these issues can be gleaned
from numerous publications by governmental agencies and
in the scientific literature. Data from these other publications
and information resources, though valuable in understanding
indoor air quality, are not presented in this report as indicators
because they are not sufficiently representative on a national
scale or because they do not track an issue over time.
The challenges associated -with filling these indicator gaps
are -well known. Although methods to monitor indoor air
U.S. Environmental Protection Agency. 1992. Respiratory health effects of
passive smoking: Lung cancer and other disorders. EPA/600/6-90/006E
Washington, DC.
U.S. Department of Health and Human Services. 2000. Healthy people 2010:
Understanding and improving health. Second edition.Washington, DC: U.S. Gov-
ernment Printing Office. November,
42 Rudel, R.A., D.E. Camann, J.D. Spengler, L.R. Korn, and J.G. Brody. 2003.
Phthalates, alkylphenols, pesticides, polybrominated diphenyl ethers, and
other endocrine-disrupting compounds in indoor air and dust. Env. Sci.Tech.
37(20):4543-4553.
43 Stapleton, H.M., N.G. Dodder, J.H. Offenberg, M.M. Schantz, and S.A.Wise.
2005. Polybrominated diphenyl ethers in house dust and clothes dryer lint.
Env. Sci.Tech. 39(4):925-931.
EPA's 2008 Report on the Environment
2-79
-------
quality are available, there is considerable variability among
building types, occupants' behaviors, climate conditions,
and ventilation systems for indoor environments in the U.S.
This variability, combined with access issues and the number
of different pollutants to address, makes a statistically based
evaluation of our nation's millions of residences, thousands of
office buildings, and more than 100,000 schools a challenging
and resource-intensive task. Further, it is difficult to directly
measure how changes in indoor air quality translate into cor-
responding changes in human health effects, because many
health outcomes attributed to poor indoor air quality (e.g.,
asthma attacks) have numerous environmental and non-envi-
ronmental risk factors.
2-80
EPA's 2008 Report on the Environment
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Chapter 3
Water
'• - • • .-
- 1C. ~ • i^= ^r-i^r^'
... **^ .^r1- • •»» i^A ^ •
-------
Contents
3.1 Introduction 3-3
3.1.1 Overview of the Data 3-4
3.1.2 Organization of This Chapter 3-4
3.2 What Are the Trends in the Extent and Condition of Fresh Surface Waters and
Their Effects on Human Health and the Environment? 3-6
3.2.1 Introduction 3-6
3.2.2 ROE Indicators 3-7
3.2.3 Discussion 3-24
3.3 What Are the Trends in the Extent and Condition of Ground Water and Their
Effects on Human Health and the Environment? 3-25
3.3.1 Introduction 3-25
3.3.2 ROE Indicators 3-27
3.3.3 Discussion 3-29
3.4 What Are the Trends in the Extent and Condition of Wetlands and Their Effects
on Human Health and the Environment? 3-30
3.4.1 Introduction 3-30
3.4.2 ROE Indicators 3-31
3.4.3 Discussion 3-35
3.5 What Are the Trends in the Extent and Condition of Coastal Waters and Their
Effects on Human Health and the Environment? 3-35
3.5.1 Introduction 3-35
3.5.2 ROE Indicators 3-37
3.5.3 Discussion 3-51
3.6 What Are the Trends in the Quality of Drinking Water and Their Effects
on Human Health? 3-52
3.6.1 Introduction 3-52
3.6.2 ROE Indicators 3-53
3.6.3 Discussion 3-56
3.7 What Are the Trends in the Condition of Recreational Waters and Their Effects
on Human Health and the Environment? 3-57
3.7.1 Introduction 3-57
3.7.2 ROE Indicators 3-58
3.7.3 Discussion 3-58
3.8 What Are the Trends in the Condition of Consumable Fish and Shellfish and
Their Effects on Human Health? 3-59
3.8.1 Introduction 3-59
3.8.2 ROE Indicators 3-60
3.8.3 Discussion . . .3-66
-------
3.1 Introduction
The nation's water resources have immeasurable value. These
resources encompass lakes, streams, ground water, coastal
waters, wetlands, and other waters; their associated ecosys-
tems; and the human uses they support (e.g., drinking water, rec-
reation, and fish consumption). The extent of water resources (their
amount and distribution) and their condition (physical, chemical,
and biological attributes) are critical to ecosystems, human uses,
and the overall function and sustainability of the hydrologic cycle.
Because the extent and condition of water can affect human
health, ecosystems, and critical environmental processes,
protecting water resources is integral to EPA's mission. EPA
•works in partnership with other government agencies that are
also interested in the extent and condition of water resources,
both at the federal level and at the state, local, or tribal level.
In this chapter, EPA seeks to assess national trends in the extent
and condition of water, stressors that influence water, and
associated exposures and effects among humans and ecologi-
cal systems. The ROE indicators in this chapter address seven
fundamental questions about the state of the nation's waters:
• What are the trends in the extent and condition
of fresh surface waters and their effects on human
health and the environment? This question focuses on
the nation's rivers, streams, lakes, ponds, and reservoirs.
• What are the trends in the extent and condition of
ground water and their effects on human health and
the environment? This question addresses subsurface
•water that occurs beneath the water table in fully saturated
soils and geological formations.
• What are the trends in the extent and condition
of wetlands and their effects on human health and
the environment? Wetlands—including swamps, bogs,
marshes, and similar areas—are areas inundated or saturated
by surface or ground water often and long enough to support
a prevalence of vegetation typically adapted for life in satu-
rated soil conditions.
• What are the trends in the extent and condition of
coastal waters and their effects on human health and
the environment? Indicators in this report present data
for \vaters that are generally within 3 miles of the coastline
(except the Hypoxia in Gulf of Mexico and Long Island
Sound indicator).
• What are the trends in the quality of drinking
water and their effects on human health? People
drink tap water, which comes from both public and private
sources, and bottled water. Sources of drinking water can
include both surface water (rivers, lakes, and reservoirs) and
ground water.
• What are the trends in the condition of recreational
waters and their effects on human health and the
environment? This question addresses water used for a wide
variety of purposes, such as swimming, fishing, and boating.
• What are the trends in the condition of consumable
fish and shellfish and their effects on human health?
This question focuses on the suitability offish and shellfish
for human consumption.
EPA's 2008 Report on the Environment (ROE): Essentials
ROE Approach
This 2008 Report on the Environment:
• Asks questions that EPA considers
important to its mission to protect
human health and the environment.
• Answers these questions, to the extent
possible, with available indicators.
• Discusses critical indicator gaps, limita-
tions, and challenges that prevent the
questions from being fully answered.
ROE Questions
The air, water, and land chapters (Chapters
2, 3, and 4) ask questions about trends in
the condition and/or extent of the envi-
ronmental medium; trends in stressors to
the medium; and resulting trends in the
effects of the contaminants in that medium
on human exposure, human health, and
the condition of ecological systems.
The human exposure and health and
ecological condition chapters (Chapters
5 and 6) ask questions about trends in
aspects of health and the environment
that are influenced by many stressors
acting through multiple media and by
factors outside EPA's mission.
ROE Indicators
An indicator is derived from actual mea-
surements of a pressure, state or ambient
condition, exposure, or human health or
ecological condition over a specified geo-
graphic domain. This excludes indicators
such as administrative, socioeconomic, and
efficiency indicators.
Indicators based on one-time studies are
included only if they were designed to serve
as baselines for future trend monitoring.
All ROE indicators passed an independent
peer review against six criteria to ensure
that they are useful; objective; transparent;
and based on data that are high-quality,
comparable, and representative across space
and time.
Most ROE indicators are reported at the
national level. Some national indicators
also report trends by region. EPA Regions
were used, where possible, for consistency
and because they play an important role in
how EPA implements its environmental
protection efforts.
Several other ROE indicators describe
trends in particular regions as examples of
how regional indicators might be included
in future versions of the ROE. They are
not intended to be representative of trends
in other regions or the entire nation.
EPA will periodically update and revise
the ROE indicators and add new indicators
as supporting data become available. In the
future, indicators will include information
about the statistical confidence of status
and trends. Updates will be posted elec-
tronically at http://www.epa.gov/roe.
Additional Information
You can find additional information about
the indicators, including the underlying
data, metadata, references, and peer review,
at http://www.epa.gov/roe.
EPA's 2008 Report on the Environment
3-3
-------
These ROE questions are posed without regard to whether
indicators are available to answer them. This chapter presents
the indicators available to answer these questions, and also
points out important gaps where nationally representative data
are lacking.
Each of the seven questions is addressed in a separate section
of this chapter. However, all the questions are fundamen-
tally connected—a fact that is highlighted throughout the
chapter text and indicator summaries. All water is part of the
global hydrologic cycle, and thus it is constantly in motion—
•whether it is a swiftly flowing stream or a slow-moving
aquifer thousands of years old. A stream may empty into a
larger river that ultimately discharges into coastal waters. An
aquifer may be recharged by surface waters, or feed surface
•waters or wetlands through springs and seeps. In each case,
the extent and condition of one water resource can affect the
extent and condition of another type. One example of this
interdependence can be found in the movement of nutrients.
Together, several of the ROE indicators track nutrient levels
in \vater bodies ranging from small wadeable streams to
coastal estuaries. Additional ROE indicators describe some
of the effects that may be associated with excess nutrients,
such as eutrophication and hypoxia.
In addition to the links within the water cycle, there are
many connections between the extent and condition of water
and other components of the environment. Air (addressed in
Chapter 2), land (Chapter 4), and water all are environmental
media, and the condition of one medium can influence the
condition of another. For example, contaminants can be trans-
ferred from air to water via deposition, or from land to water
through runoff or leaching.
Chapter 5, "Human Exposure and Health," and Chapter 6,
"Ecological Condition," examine the relationships between
human life, ecosystems, and some of the environmental condi-
tions that can affect them. Humans and ecosystems depend
on \vater, so stressors that affect the extent and condition of
•water—such as droughts, pathogens, and contaminants—may
ultimately affect human health or ecological condition.
3.1.1 Overview of the Data
The indicators in this chapter reflect several different methods
of collecting and analyzing data on the extent and condition
of \vater resources; in some cases, indicators employ a combi-
nation of methods. Some of the indicators in this chapter are
based on probabilistic surveys, -with sample or monitoring loca-
tions chosen to be representative of a large area (e.g., an EPA
Region or the nation as a -whole). Examples of probabilistic
surveys include EPA's Wadeable Streams Survey and National
Coastal Assessment, and the U.S. Fish and Wildlife Service's
Wetlands Status and Trends Survey. Other indicators reflect
targeted sampling or monitoring—for example, collecting
•water samples in an area prone to hypoxia in order to ascertain
the extent and duration of a particular hypoxic event. In some
cases, data are based on regulatory reporting, -which may in
turn reflect probabilistic or targeted sampling. For example, the
ROE indicator on drinking -water is based on review of moni-
toring conducted by -water systems, -with results reported by the
states to EPA, as required by federal law.
One of the challenges in assessing the extent and condition
of-water resources is that a single data collection method is
rarely perfect for every combination of spatial and temporal
domains. In general, there is an inherent tradeoff in represent-
ing trends in -water resources. For example, a probabilistic sur-
vey may provide an accurate representation of national trends,
but the resolution may be too low to definitively characterize
the resource at a smaller scale. In some cases, results can be
disaggregated to the scale of EPA Regions or ecoregions -with-
out losing precision. However, these indicators are generally
not designed to inform the reader about the condition of his
or her local -water bodies, for example, or the quality of locally
harvested fish.
Like-wise, it is often convenient to compare trends in terms of
annual averages—particularly -where it is not practical to col-
lect data every day of the year. However, averaging and peri-
odic sampling can obscure or overlook extreme events, such as
spikes in -water contaminants after a pesticide application or a
large storm. Thus, representative extent or condition data can-
not depict the full range of variations and extremes—some of
•which may be critical to ecosystems or to humans—that occur
in smaller areas or on smaller time scales.
This chapter presents only data that meet the ROE indicator
definition and criteria (see Box 1-1, p. 1-3). Note that non-
scientific indicators, such as administrative and economic
indicators, are not included in this definition. Thorough
documentation of the indicator data sources and metadata
can be found online at http://www.epa.gov/roe. All indica-
tors \vere peer-reviewed during an independent peer review
process (again, see http://www.epa.gov/roe for more infor-
mation). Readers should not infer that the indicators in this
chapter reflect the complete state of knowledge. Many other
data sources, publications, and site-specific research projects
have contributed substantially to the current understanding of
status and trends in water, but are not included in this report
because they do not meet the ROE indicator criteria.
3.1.2 Organization of This Chapter
The remainder of this chapter is organized into seven sections
corresponding to the seven questions that EPA seeks to answer
about trends in water. Each section introduces a question and
discusses its importance, presents the ROE indicators used to
help answer the question, and discusses what the indicators,
taken together, say about the question. The ROE indicators
include National Indicators as well as several Regional Indica-
tors that meet the ROE definition and criteria and help to
answer a question at a smaller geographic scale. Each section
concludes by highlighting the major challenges to answering
the question and identifying important information gaps.
Table 3-1 lists the indicators used to answer the seven ques-
tions in this chapter and shows the locations where the indica-
tors are presented.
3-4
EPA's 2008 Report on the Environment
-------
Table 3-1. Water—ROE Questions and Indicators
Question
What are the trends in the extent and
condition of fresh surface waters and
their effects on human health and the
environment?
What are the trends in the extent
and condition of ground water and
their effects on human health and the
environment?
What are the trends in the extent
and condition of wetlands and their
effects on human health and the
environment?
What are the trends in the extent
and condition of coastal waters and
their effects on human health and the
environment?
What are the trends in the quality of
drinking water and their effects on
human health?
What are the trends in the condition
of recreational waters and their
effects on human health and the
environment?
What are the trends in the condition
of consumable fish and shellfish and
their effects on human health?
Indicator Name
High and Low Stream Flows (N)
Streambed Stability in Wadeable Streams (N)
Lake and Stream Acidity (N)
Nitrogen and Phosphorus in Wadeable Streams (N)
Nitrogen and Phosphorus in Streams in Agricultural
Watersheds (N)
Nitrogen and Phosphorus Loads in Large Rivers (N)
Pesticides in Streams in Agricultural Watersheds (N)
Benthic Macroinvertebrates in Wadeable Streams (N)
Nitrate and Pesticides in Shallow Ground Water in
Agricultural Watersheds (N)
Wetland Extent, Change, and Sources of Change (N)
Wetland Extent, Change, and Sources of Change (N)
Trophic State of Coastal Waters (N/R)
Coastal Sediment Quality (N/R)
Coastal Benthic Communities (N/R)
Coastal Fish Tissue Contaminants (N/R)
Submerged Aquatic Vegetation in the Chesapeake Bay (R)
Hypoxia in the Gulf of Mexico and Long Island Sound (R)
Population Served by Community Water Systems with No
Reported Violations of Health-Based Standards (N/R)
No ROE indicators
Coastal Fish Tissue Contaminants (N/R)
Contaminants in Lake Fish Tissue (N)
Section Page
3.2.2
3.2.2
2.2.2
3.2.2
3.2.2
3.2.2
3.2.2
3.2.2
3.3.2
3.4.2
3.4.2
3.5.2
3.5.2
3.5.2
3.8.2
3.5.2
3.5.2
3.6.2
3.8.2
3.8.2
3-8
3-11
2-42
3-13
3-15
3-17
3-19
3-21
3-27
3-32
3-32
3-38
3-42
3-44
3-61
3-46
3-48
3-54
3-61
3-63
N = National Indicator
R = Regional Indicator
N/R = National Indicator displayed at EPA Regional scale
EPA's 2008 Report on the Environment
3-5
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3.2 What Are the
Trends in the Extent
Condition
Fresh Surface Waters
and Their Effects on
Human Health and the
Environment?
3.2.1 Introduction
Though lakes, ponds, rivers, and streams hold less than one
thousandth of a percent of the water on the planet, they
serve many critical functions for the environment and for
human life. These fresh surface waters sustain ecological
systems and provide habitat for many plant and animal spe-
cies. They also support a myriad of human uses, including
drinking water, irrigation, wastewater treatment, livestock,
industrial uses, hydropower, and recreation. Fresh surface
•waters also influence the extent and condition of other water
resources, including ground water, wetlands, and coastal
systems downstream.
The extent of fresh surface waters reflects the influence and
interaction of many stressors. It can be affected by direct with-
drawal for drinking, irrigation, industrial processes, and other
human use, as well as by the withdrawal of ground water,
•which replenishes many surface waters. Hydromodifications
such as dam construction can create new impoundments and
fundamentally alter stream flow. Land cover can affect drain-
age patterns (e.g., impervious pavement may encourage runoff
or flooding). Weather patterns—e.g., the amount of precipita-
tion, the timing of precipitation and snowmelt, and the condi-
tions that determine evaporation rates—also affect the extent
of fresh surface waters. Changing climate could also affect the
extent of fresh surface water that is available.
The condition of fresh surface waters reflects a range of char-
acteristics. Physical characteristics include attributes such as
temperature and clarity. Chemical characteristics include
attributes such as salinity, nutrients, and chemical contami-
nants (including contaminants in sediments, which can impact
•water quality and potentially enter the aquatic food web).
Biological characteristics include diseases, pathogens, and—in
a broader sense—the status of plant and animal populations
and the condition of their habitat. In addition to their effects
on the environment, many of these characteristics can ulti-
mately affect human health, mainly through drinking water,
recreational activities (e.g., health effects in swimmers due
to pathogens and harmful algal blooms), or consumption of
fish and shellfish. Because these three topics are complex and
encompass many types of water bodies, each is addressed in
greater detail in its own section of this report (see Sections 3.6,
3.7, and 3.8, respectively).
Like extent, the condition of fresh surface waters can be influ-
enced by a combination of natural and anthropogenic stressors,
such as:
• Point source pollution, including contaminants dis-
charged directly into water bodies by industrial opera-
tions, as \vell as nutrients and contaminants in sewage. Even
treated sewage contains nutrients that affect the chemical
composition of the water.
• Nonpoint source pollution, which largely reflects con-
taminants, nutrients, and excess sediment in runoff from
urban and suburban areas (e.g., stormwater) and agricultural
land. Other sources include recreational activities (e.g.,
boating and marinas) and acid mine drainage. Nonpoint
source pollution can be influenced by land cover (e.g.,
impervious surfaces that encourage runoff) and land use
(e.g., certain forestry techniques and agricultural practices
that encourage runoff and erosion). Nonpoint sources
tend to be more variable than point sources. For example,
pesticide concentrations in streams reflect the location and
timing of pesticide application.
• Air deposition. Acidic aerosols, heavy metals, and other
airborne contaminants may be deposited directly on water
or may wash into water bodies after deposition on land.
For example, mercury emitted to the air from combustion
at power plants can be transported and deposited in lakes
and reservoirs.
• Invasive species. Invasives are non-indigenous plant and
animal species that can harm the environment, human
health, or the economy.1 Invasive species can crowd out
native species and alter the physical and chemical condition
of \vater bodies.
• Natural factors. Precipitation determines the timing
and amount of runoff and erosion, while other aspects of
•weather and climate influence heating, cooling, and mixing
in lakes—which affect the movement of contaminants and
the cycling of nutrients. The mineral composition of bed-
rock and sediment helps determine whether a water body
may be susceptible to acidification.
The condition of fresh surface waters also may be influenced
by extent. Stream flow patterns influence contaminant and
sediment loads, while changes in the shape of water bodies—
e.g., eliminating deep pools or creating shallow impound-
ments—can change water temperature. The extent of surface
•waters also represents the extent of habitat—a key aspect of
biological condition. Some plant and animal communities
are sensitive to water level (e.g., riparian communities), while
National Invasive Species Council. 2005. Five year review of Executive Order
13112 on invasive species. Washington, DC: U.S. Department of the Interior.
3-6
EPA's 2008 Report on the Environment
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others may be adapted to particular seasonal fluctuations in
flow. Stressors that affect extent may ultimately affect the
condition of freshwater habitat—for example, hydromodifi-
cations that restrict the migration of certain fish species.
3.2.2 ROE Indicators
Eight ROE indicators characterize either the extent or the con-
dition of fresh surface waters (Table 3-2). One of these indica-
tors presents information about stream flow patterns, an aspect
of surface water extent. The other seven indicators characterize
various aspects of condition, including the physical condition
of sediments, the condition of benthic communities, and the
chemical condition of the water itself. Several of these indica-
tors track concentrations of nutrients, which can impact many
different types of water bodies if present in excess (e.g., through
eutrophication). Supporting data come from several national
monitoring programs: EPA's Environmental Monitoring and
Assessment Program (EMAP), EPA's Wadeable Streams Assess-
ment, EPA's Temporally Integrated Monitoring of Ecosystems
(TIME) and Long-Term Monitoring (LTM) projects, and
three programs administered by the U.S. Geological Survey
(USGS) (the National Water Quality Assessment [NAWQA]
program, the National Stream Quality Accounting Net-work
[NASQAN], and the USGS stream gauge network).
Table 3-2. ROE Indicators of Trends in the Extent and Condition of
Fresh Surface Waters and Their Effects on Human Health and the Environment
National Indicators
Section
High and Low Stream Flows
Streambed Stability in Wadeable Streams
Lake and Stream Acidity
Nitrogen and Phosphorus in Wadeable Streams
Nitrogen and Phosphorus in Streams in Agricultural Watersheds
Nitrogen and Phosphorus Loads in Large Rivers
Pesticides in Streams in Agricultural Watersheds
Benthic Macroinvertebrates in Wadeable Streams
3.2.2
3.2.2
2.2.2
3.2.2
3.2.2
3.2.2
3.2.2
3.2.2
3-8
3-11
2-42
3-13
3-15
3-17
3-19
3-21
EPA's 2008 Report on the Environment
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INDICATOI
High and Low Stream Flows
50
40
30
° 20
10
1960
Flow is a critical aspect of the physical struc-
ture of stream ecosystems (Poff and Allan,
1995; Robinson et al, 2002). High flows shape
the stream channel and clear silt and debris from
the stream, and some fish species depend on
high flows for spawning. Low flows define the
smallest area available to stream biota during the
year. In some cases, the lowest flow is no flow at
all—particularly in arid and semi-arid regions
•where intermittent streams are common.
Riparian vegetation and aquatic life in intermit-
tent streams have evolved to complete their life
histories during periods when water is available;
however, extended periods of no flow can still
impact their survival (Fisher, 1995). Changes in
flow can be caused by dams, water withdrawals,
ground water pumping (which can alter base
flow), changes in land cover (e.g., deforesta-
tion or urbanization), and weather and climate
(Calow and Petts, 1992).
This indicator, developed by the Heinz Cen-
ter (in press), describes trends in stream flow
volumes based on daily flow data collected by
the U.S. Geological Survey's (USGS's) nation-
wide net-work of stream flow gauging sites
from 1961 to 2006.
The first part of this indicator describes
trends in high flow volume, low flow volume,
and variability of flow in streams throughout
the contiguous 48 states, relative to a baseline
period of 1941-1960. Data were collected at
two sets of USGS stream gauging stations: a
set of approximately 700 "reference" streams
that have not been substantially affected by
dams and diversions and have had little change
in land use over the measurement period, and
a separate set of approximately 1,000 "non-
reference" streams that reflect a variety of
conditions (the exact number of sites with suf-
ficient data varies from one metric to another).
The indicator is based on each site's annual
3-day high flow volume, 7-day low flow vol-
ume, and variability (computed as the difference between
the 1st and 99th percentile 1-day flow volumes in a given
year, divided by the median 1-day flow). Annual values
for each metric were examined using a rolling 5-year
window to reduce the sensitivity to anomalous events. For
each site, the median value for the 5-year window was
compared to the median value for the 1941-1960 baseline
period. The indicator shows the proportion of sites where
high flow, low flow, or variability of flow was more than
30 percent higher or 30 percent lower than the baseline. It
also shows differences of more than 60 percent.
Exhibit 3-1. Changes in high flow in rivers and streams of
the contiguous U.S., 1961-2006, compared with 1941-1960
baseline3"
A. Increased high flow volume
>30% increase
— Non-reference
streams
— Reference
streams
>60% increase
— Non-reference
streams
Reference
streams
1970
1980
1990
2000
2010
50
40
30
° 20
10
Year
B. Decreased high flow volume
>30% decrease
— Non-reference
streams
— Reference
streams
>60% decrease
— Non-reference
streams
Reference
streams
1960
1970
1980
1990
2000
2010
Year
'Coverage: 1,719 stream gauging sites (712 reference, 1,007 non-reference) in the
contiguous U.S. with flow data from 1941 to 2006. Reference streams have not
been substantially affected by dams and diversions; non-reference streams may or
may not have been affected in this way.
'Based on the annual 3-day high flow. For each stream site, the median high flow
was determined over a rolling 5-year window, then compared against the baseline.
Results are plotted at the midpoint of each window. For example, the value for
2002-2006 is plotted at the year 2004.
Data source: Heinz Center, 2007
This indicator also examines no-flow periods in streams
in grassland and shrubland areas of the contiguous 48 states.
Data represent 280 USGS "reference" and "non-reference"
stream gauging sites in -watersheds -with at least 50 percent
grass or shrub cover, as defined by the 2001 National Land
Cover Database (NLCD) (MRLC Consortium, 2007). The
indicator reports the percentage of these streams -with at
least one no-flow day in a given year, averaged over a roll-
ing 5-year window. Results are displayed for all grassland/
shrubland streams, as -well as for three specific ecoregion
divisions (Bailey, 1995). This indicator also reports on the
duration of no-flow periods. For a subset of 163 grassland/
3-8
EPA's 2008 Report on the Environment
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INDICATO
High and Low Stream Flows
shrubland streams that had at least one no-flow
day during the study period, the duration of
the maximum no-flow period in each year was
averaged over a rolling 5-year window and
compared with the average no-flow duration
for the same site during the 1941-1960 baseline
period. A no-flow period more than 14 days
longer than the baseline was described as a
"substantial increase"; a no-flow period more
than 14 days shorter than the baseline was clas-
sified as a "substantial decrease."
What the Data Show
In an average year during the period of
record, roughly 20 percent of streams had
increases in high flow volume of more than
30 percent, relative to the 1941-1960 baseline
(Exhibit 3-1, panel A). A similar percent-
age had decreases of more than 30 percent
(Exhibit 3-1, panel B). Large fluctuations in
high flow volume are apparent over time,
•with both sets of trends suggesting relatively
wet periods in the early 1980s and mid-1990s
and relatively dry periods around 1990 and
the early 2000s. Reference and non-reference
stream sites show similar patterns, although
larger decreases in high flow volume were
more common in the non-reference streams.
Since the early 1960s, more streams have
shown increases in low flow volumes than have
shown decreases, relative to the 1941-1960
baseline period (Exhibit 3-2). Among the many
streams with larger low flows are a few (2 to
4 percent in an average year) with increases of
more than 600 percent. Fluctuations over time
are apparent, and while not as pronounced
as the shifts in high flow (Exhibit 3-1), they
generally tend to mirror the same relatively wet
and dry periods. Reference and non-reference
streams show similar low flow patterns over
time, but reference sites are less likely to have
experienced decreases in low flow.
Except for a few brief periods in the mid-1960s and again
around 1980, decreased flow variability has been much more
common than increased variability (Exhibit 3-3). Refer-
ence and non-reference streams have shown similar patterns
in variability over time, although reference streams were
slightly less likely to experience changes overall.
In areas with primarily grass or shrub cover, roughly 15 to
20 percent of stream sites typically have experienced periods
of no flow in a given year (Exhibit 3-4). Overall, the number
of streams experiencing no-flow periods has declined slightly
since the 1960s. Streams in the California/Mediterranean
Exhibit 3-2. Changes in low flow in rivers and streams of
the contiguous U.S., 1961-2006, compared with 1941-1960
baseline3"
A. Increased low flow volume
1970
1980
1990
2000
2010
Year
Decreased low flow volume
>30% increase
— Non-reference
streams
— Reference
streams
>60% increase
Non-reference
streams
— Reference
streams
>600% increase
—Non-reference
streams
— Reference
streams
>30% decrease
— Non-reference
streams
— Reference
streams
>60% decrease
Non-reference
streams
Reference
streams
1970
1980
1990
2000
2010
Year
Coverage: 1,609 stream gauging sites (673 reference, 936 non-reference) in the
contiguous U.S. with flow data from 1941 to 2006. Reference streams have not
been substantially affected by dams and diversions; non-reference streams may or
may not have been affected in this way.
bBased on the annual 7-day low flow. For each stream site, the median low flow was
determined over a rolling 5-year window, then compared against the baseline.
Results are plotted at the midpoint of each window. For example, the value for
2002-2006 is plotted at the year 2004.
Data source: Heinz Center, 2007
ecoregion have shown the greatest decrease in no-flow fre-
quency, but they still experience more no-flow periods than
streams in the other two major grassland/shrubland ecoregion
divisions. Among grassland/shrubland streams that have expe-
rienced at least one period of no flow since 1941, more streams
have shown a substantial decrease in the duration of no-flow
periods (relative to the 1941-1960 baseline) than a substantial
increase (Exhibit 3-5).
Indicator Limitations
• The 1941-1960 baseline period was chosen to maximize
the number of available reference sites and should
EPA's 2008 Report on the Environment
3-9
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INDICATOR
High and Low Stream Flows (continued)
provide a sufficiently long window to account
for natural variability (Heinz Center, in
press); however, it does not necessarily reflect
"undisturbed" conditions. Many darns and
waterworks had already been constructed by
1941, and other anthropogenic changes (e.g.,
urbanization) were already -widespread.
• Although the sites analyzed here are spread
•widely throughout the contiguous U.S.,
gauge placement by USGS is not a random
process. Gauges are generally placed on larger,
perennial streams and rivers, and changes seen
in these larger systems may differ from those
seen in smaller streams and rivers.
• This indicator does not characterize trends
in the timing of high and low stream flows,
•which can affect species migration, repro-
duction, and other ecological processes.
Data Sources
The data presented in this indicator were pro-
vided by the Heinz Center (2007), which con-
ducted this analysis for a forthcoming update
to its report, The State of the Nation's Ecosystems
(Heinz Center, in press). Underlying stream
flow measurements can be obtained from the
USGS National Water Information System
database (USGS, 2007) (http://waterdata.usgs.
gov/nwis).
References
Bailey, R.G. 1995. Description of the ecore-
gions of the United States. Second edition.
Misc. Publ. No. 1391 (rev). Washington, DC:
USDA Forest Service,
Calow, P., and G.E. Petts, eds. 1992.
The rivers handbook: Hydrological and
ecological principles. Volume 1. Oxford, UK:
Black-well Scientific.
Exhibit 3-3. Changes in flow variability in rivers and streams
of the contiguous U.S., 1961-2006, compared with
1941-1960 baseline3b
A. Increased flow variability
>30% increase
— Non-reference
streams
— Reference
streams
>60% increase
Non-reference
streams
Reference
streams
1960
1970
1980
1990
2000
2010
Year
50
« 40
&
'co
I 30
CD
to
2 20
d
CD
°- 10
0
B. Decreased flow variability
>30% decrease
— Non-reference
streams
— Reference
streams
>60% decrease
— Non-reference
streams
Reference
streams
1960
1970
1980 1990
Year
2000
2010
Coverage: 1,754 stream gauging sites (733 reference, 1,021 non-reference) in the
contiguous U.S. with flow data from 1941 to 2006. Reference streams have not
been substantially affected by dams and diversions; non-reference streams may or
may not have been affected in this way.
bBased on the annual range of 1 -day flows. For each stream site, the median
variability was determined over a rolling 5-year window, then compared against the
baseline. Results are plotted at the midpoint of each window. For example, the value
for 2002-2006 is plotted at the year 2004.
Data source: Heinz Center, 2007
Fisher, S.G. 1995. Stream ecosystems of the
•western United States. In: Gushing, C.E., KW. Cum-
mings, and GW. Minshall, eds. River and stream eco-
systems, ecosystems of the world 22. New York, NY:
Elsevier.
Heinz Center (The H. John Heinz III Center for Science,
Economics, and the Environment). 2007. Data provided to
EPA by Anne Marsh, Heinz Center. October 15, 2007.
Heinz Center. In press. The state of the nation's ecosys-
tems: Measuring the lands, waters, and living resources of
the United States. 2007 update.
MRLC Consortium. 2007. National Land Cover Database
2001 (NLCD 2001). Accessed 2007.
Poff, N.L., andJ.D. Allan. 1995. Functional organization
of stream fish assemblages in relation to hydrologic vari-
ability. Ecology 76:606-627.
Robinson, C.T., K. Tockner, andJ.V. Ward. 2002. The fauna
of dynamic riverine landscapes. Freshwater Biol. 47:661-677.
USGS (United States Geological Survey). 2007. National
Water Information System. Accessed 2007.
3-10
EPA's 2008 Report on the Environment
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INDICATOI
High and Low Stream Flows (continued)
Exhibit 3-4. Percent of grassland/shrubland
streams in the contiguous U.S. experiencing
periods of no flow, by ecoregion, 1961-2006ab
100
a
'
60
20
1960
1970
1980 1990
Year
2000
2010
Ecoregion:
— California/Mediterranean
Desert/shrub
— Grassland/steppe
—All three of these ecoregions
Ecoregion divisions
-Desert/shrub
California/ Grassland/
Mediterranean steppe
Coverage: 280 stream gauging sites in watersheds containing 50
percent or greater grass/shrub cover, with flow data from 1941 to
2006. Grass/shrub cover refers to classes 52 and 71 of the 2001
National Land Cover Database (NLCD).
bStreams were classified based on annual data, then the
percentage of streams in each category was averaged over a
rolling 5-year window. Results are plotted at the midpoint of each
window. For example, the average for 2002-2006 is plotted at the
year 2004.
:Ecoregions based on Bailey (1995).
Data source: Heinz Center, 2007
Exhibit 3-5. Changes in the maximum duration
of no-flow periods in intermittent grassland/
shrubland streams of the contiguous U.S.,
1961-2006, compared with 1941-1960 baseline3 b
100
80
60
40
20
1960
1970
1980 1990
Year
2000
2010
Coverage: 163 stream gauging sites in
watersheds containing 50 percent or greater
grass/shrub cover, with flow data from
1941 to 2006 and at least one no-flow day
during this period. Grass/shrub cover refers
to classes 52 and 71 of the 2001 National
Land Cover Database (NLCD).
bFor each stream site, the duration of the maximum no-flow period
in each year was averaged over a rolling 5-year window. Results
are plotted at the midpoint of each window. For example, the value
for 2002-2006 is plotted at the year 2004.
:A substantial increase means the no-flow period was more than 14
days longer than the average duration during the 1941-1960
baseline period; a substantial decrease means the no-flow period
was more than 14 days shorter.
Data source: Heinz Center, 2007
reambed Stability in Wadeable Streams
Streams and rivers adjust their channel shapes and
particle sizes in response to the supply of water and
sediments from their drainage areas, and this in turn can
affect streambed stability. Lower-than-expected streambed
stability is associated with excess sedimentation, which
may result from inputs of fine sediments from erosion—
including erosion caused by human activities such as agri-
culture, road building, construction, and grazing. Unstable
streambeds may also be caused by increases in flood
magnitude or frequency resulting from hydrologic altera-
tions. Lower-than-expected streambed stability may cause
stressful ecological conditions when, for example, excessive
amounts of fine, mobile sediments fill in the habitat spaces
between stream cobbles and boulders. When coupled with
increased stormflows, unstable streambeds may also lead to
channel incision and arroyo formation, and can negatively
affect benthic invertebrate communities and fish spawn-
ing (Kaufmann et al., 1999). The opposite condition—an
overly stable streambed—is less common, and generally
reflects a lack of small sediment particles. Overly stable
streambeds can result from reduced sediment supplies or
EPA's 2008 Report on the Environment
3-11
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INDICATOR
Stream bed Stability in Wadeable Streams (continued)
Exhibit
streams
100
80
CO
_0
'E
E 60
ro
o
"co
"o
^ 40
8
o3
Q_
20
0
3-6. Streambed stability in wadeable
of the contiguous U.S., 2000-20043
5.3
50.1
19.7
24.9
D Not assessed/no data
D Least disturbed
D Moderately disturbed
D Most disturbed
Compared with minimally
disturbed reference sites.
See text for definitions of the
categories shown in the figure.
Data source: U.S. EPA, 2006b
stream flows, or from prolonged conditions of high sedi-
ment transport without an increase in sediment supply.
This indicator is based on the Relative Bed Stability
(RBS), which is one measure of the interplay between sedi-
ment supply and transport. RBS is the ratio of the observed
mean streambed particle diameter to the "critical diameter,"
the largest particle size the stream can move as bedload
during storm flows. The critical diameter is calculated from
field measurements of the size, slope, and other physi-
cal characteristics of the stream channel (Kaufmann et al.,
1999). A high RBS score indicates a coarser, more stable
bed—i.e., streambed particles are generally much larger than
the biggest particle the stream could carry during a storm
flow. A low RBS score indicates a relatively unstable stream-
bed, consisting of many fine particles that could be carried
away by a storm flow. Expected values of RBS are based on
the statistical distribution of values observed at reference sites
that are known to be relatively undisturbed. RBS values that
are substantially lower than the expected range are consid-
ered to be indicators of ecological stress.
This indicator is based on data collected for EPA's Wade-
able Streams Assessment (WSA). Wadeable streams are
streams, creeks, and small rivers that are shallow enough
to be sampled using methods that involve wading into
the water. They typically include waters classified as 1st
through 4th order in the Strahler Stream Order classifica-
tion system (Strahler, 1952). The WSA is based on a proba-
bilistic design, so the results from representative sample
sites can be used to make a statistically valid statement
about streambed stability in wadeable streams nation-wide.
Crews sampled 1,392 randomized sites throughout
the U.S. using standardized methods (U.S. EPA, 2004).
Western sites were sampled between 2000 and 2004;
eastern and central sites were all sampled in 2004. Sites
•were sampled between mid-April and mid-November. At
each site, crews measured substrate particle size, streambed
dimensions, gradient, and stream energy dissipators (e.g.,
pools and woody debris), then used these factors to calcu-
late the RBS.
Because streambed characteristics vary geographically,
streams were divided into nine broad ecoregions (U.S. EPA,
2006b), \vhich \vere defined by the WSA based on group-
ings of EPA Level III ecoregions (Omermk, 1987; U.S. EPA,
2007). In each ecoregion, a set of relatively undisturbed sites
•was sampled in order to determine the range of RBS values
that \vould be expected among "least disturbed" streams.
Next, the RBS for every site was compared to the distribu-
tion of RBS values among the ecoregion's reference sites.
If the observed RBS for a sample site was below the 5th or
the 10th percentile of the regional reference distribution
(depending on the ecoregion), the site was classified as "most
disturbed." This threshold was used because it offers a high
degree of confidence that the observed condition is statisti-
cally different from the "least disturbed" reference condi-
tion. Any stream with an RBS above the 25th percentile of
the reference range was labeled "least disturbed," indicat-
ing a high probability that the site is similar to the rela-
tively undisturbed reference sites. Streams falling between
the 5th and 25th percentiles were classified as "moderately
disturbed." Note that the "least disturbed" category may
include some streams with higher-than-expected RBS
values, \vhich represent overly stable streambeds. Because it
is more difficult to determine whether overly stable stream-
beds are "natural" or result from anthropogenic factors, this
indicator only measures the prevalence of unstable streambeds
(i.e., excess sedimentation).
What the Data Show
Roughly 50 percent of wadeable stream miles are classified
as "least disturbed" -with respect to streambed condition;
that is, their streambed stability is close to or greater than
•what \vould be expected (Exhibit 3-6). Conversely, 25 per-
cent of the nation's wadeable streambeds are significantly
less stable than regional reference conditions for streambed
stability ("most disturbed"), and an additional 20 percent
are classified as "moderately disturbed." Approximately 5
percent of the nation's stream length could not be assessed
because of missing or inadequate sample data.
Indicator Limitations
• Samples -were taken one time from each sampling
location during the index period (April-November).
Although the probability sampling design results in unbi-
ased estimates for relative streambed stability in wadeable
streams during the study period, RBS values may be
different during other seasons and years because of varia-
tions in hydrology.
3-12
EPA's 2008 Report on the Environment
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INDICATOI
Stream bed Stability in Wadeable Streams (continued)
• Trend data are unavailable because this is the first time
that a survey on this broad scale has been conducted, and
the survey design does not allow trends to be calculated
\vithin a single sampling period (2000-2004). These data
•will serve as a baseline for future surveys.
Data Sources
Aggregate data for this indicator were provided by EPA's
Wadeable Streams Assessment (U.S. EPA, 2006b). Data
from individual stream sites can be obtained from EPA's
STORET database (U.S. EPA, 2006a) (http://www.epa.
gov/owow/streamsurvey/web_data.html).
References
Kaufmann, PR., P. Levine, E.G. Robison, C. Seeliger, and
D. Peck. 1999. Quantifying physical habitat in wadeable
streams. EPA/620/R-99/003. Washington, DC: U.S. Envi-
ronmental Protection Agency,
Omernik, J.M. 1987. Ecoregions of the conterminous
United States. Map (scale 1:7,500,000). Ann. Assoc. Am.
Geog. 77(1):118-125.
Strahler, A.N. 1952. Dynamic basis of geomorphology.
Geol. Soc. Am. Bull. 63:923-938.
U.S. EPA (United States Environmental Protection
Agency). 2007. Level III ecoregions of the conterminous
United States. Accessed November 2007.
U.S. EPA. 2006a. Data from the Wadeable Streams Assess-
ment. Accessed 2006.
U.S. EPA. 2006b. Wadeable Streams Assessment: A collab-
orative survey of the nation's streams. EPA/841/B-06/002.
U.S. EPA. 2004. Wadeable Streams Assessment: Field
operations manual. EPA/841/B-04/004.
Nitrogen and Phosphorus in Wadeable Streams
Nitrogen and phosphorus are essential elements in
aquatic ecosystems. Both nutrients are used by plants
and algae for growth (U.S. EPA, 2005). Excess nutrients,
however, can lead to increased algal production, and excess
nutrients in streams can also affect lakes, larger rivers, and
coastal \vaters downstream. In addition to being visually
unappealing, excess algal growth can contribute to the loss
of oxygen needed by fish and other animals, which in turn
can lead to altered biological assemblages. Sources of excess
nutrients include municipal sewage and septic tank drain-
fields, agricultural runoff, excess fertilizer application, and
atmospheric deposition of nitrogen (Herlihy et al., 1998).
This indicator measures total phosphorus and total nitro-
gen based on data collected for EPA's Wadeable Streams
Assessment (WSA). Wadeable streams—streams, creeks,
and small rivers that are shallow enough to be sampled
using methods that involve wading into the water—repre-
sent a vital linkage between land and water. They typi-
cally include -waters classified as 1st through 4th order in the
Strahler Stream Order classification system (Strahler, 1952).
The WSA is based on a probabilistic design, so the results
from representative sample sites can be used to make a
statistically valid statement about nitrogen and phosphorus
concentrations in all of the nation's wadeable streams.
Crews sampled 1,392 randomized sites across the United
States using standardized methods. Western sites -were
sampled between 2000 and 2004; eastern and central sites
•were all sampled in 2004. All sites were sampled between
mid-April and mid-November. At each site, a water sample
•was collected at mid-depth in the stream and analyzed fol-
io-wing standard laboratory protocols (U.S. EPA, 2004a,b).
Because naturally occurring nutrient levels vary from
one geographic area to another, streams were divided into
nine broad ecoregions (U.S. EPA, 2006b), which were
defined by the WSA based on groupings of EPA Level
III ecoregions (Omernik, 1987; U.S. EPA, 2007). In each
ecoregion, a set of relatively undisturbed sites was sampled
in order to determine the range of nutrient concentra-
tions that \vould be considered "low." Next, observed
nitrogen and phosphorus concentrations from all sites -were
compared to the distribution of concentrations among the
ecoregion's reference sites. If the observed result -was above
the 95th percentile of the ecoregion's reference distribu-
tion, the concentration -was labeled "high." This threshold
•was used because it offers a high degree of confidence that
the observed condition is statistically different from the
condition of the reference streams. Concentrations below
the 75th percentile of the reference range -were labeled
EPA's 2008 Report on the Environment
3-13
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INDICATOR
Nitrogen and Phosphorus in Wadeable Streams (continued)
Exhibit 3-7. Nitrogen and phosphorus in
wadeable streams of the contiguous U.S.
2000-20043
100
A. Total nitrogen B. Total phosphorus
60
40
20
0
4.2-
_ .
43.3
20.7
31.8
4.2
_ .
48.8
16.1
30.9
Concentration:
D Not assessed/
no data
• Low
D Moderate
DHigh
Compared with minimally disturbed reference sites. See text for
definitions of the categories shown in the figure.
Data source: U.S. EPA, 2006b
"low," indicating a high probability that the site is similar
to the relatively undisturbed reference sites. Concentrations
falling between the 75th and 95th percentiles were labeled
"moderate."
What the Data Show
Nationwide, 43.3 percent of wadeable stream miles had
low total nitrogen concentrations, while high nitrogen
concentrations were found in 31.8 percent of stream miles
(Exhibit 3-7). The results for total phosphorus are simi-
lar to those for nitrogen, with low concentrations in 48.8
percent of stream miles and high concentrations in 30.9
percent (Exhibit 3-7). The concentrations associated with
the regional thresholds vary because of natural differ-
ences among the ecoregions. Approximately 4 percent of
the nation's wadeable stream length could not be assessed
because of missing or inadequate sample data.
Indicator Limitations
• Samples were taken one time from each sampling
location during the index period (April-November).
Although the probability sampling design results in an
unbiased estimate for total nitrogen and phosphorus con-
centrations in wadeable streams during the study period,
concentrations may be different during other seasons.
• Trend data are unavailable because this is the first time
that a survey on this broad scale has been conducted, and
the survey design does not allow trends to be calculated
\vithin a single sampling period (2000-2004). These data
•will serve as a baseline for future surveys.
• Not all forms of nitrogen and phosphorus are equally
bioavailable, and the ratio of nitrogen to phosphorus
can affect the biomass and type of species of algae in
streams. The forms of nitrogen and phosphorus and the
nitrogen:phosphorus ratios may vary somewhat between
the regional reference sites and the WSA streams.
Data Sources
Aggregate data for this indicator were provided by the
WSA (U.S. EPA, 2006b). Data from individual stream
sites can be obtained from EPA's STORET database (U.S.
EPA, 2006a) (http://www.epa.gov/owow/streamsurvey/
web_data.html).
References
Herlihy, A.T., J.L. Stoddard, and C.B.Johnson. 1998. The
relationship between stream chemistry and -watershed land
use data in the Mid-Atlantic region. US Water Air Soil
Pollut. 105:377-386.
Omernik, J.M. 1987. Ecoregions of the conterminous
United States. Map (scale 1:7,500,000). Ann. Assoc. Am.
Geog. 77(1):118-125.
Strahler, A.N. 1952. Dynamic basis of geomorphology.
Geol. Soc. Am. Bull. 63:923-938.
U.S. EPA (United States Environmental Protection
Agency). 2007. Level III ecoregions of the conterminous
United States. Accessed November 2007.
U.S. EPA. 2006a. Data from the Wadeable Streams
Assessment. Accessed 2006.
U.S. EPA. 2006b. Wadeable Streams Assessment: A collab-
orative survey of the nation's streams. EPA/841/B-06/002.
U.S. EPA. 2005. National estuary program—challenges
facing our estuaries. Key management issues: Nutri-
ent overloading,
U.S. EPA. 2004a. Wadeable Streams Assessment: Field
operations manual. EPA/841/B-04/004.
U.S. EPA. 2004b. Wadeable Streams Assessment: Water
chemistry laboratory manual. EPA/841/B-04/008.
3-14
EPA's 2008 Report on the Environment
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Nitrogen and Phosphorus in Streams in Agricultural
Watersheds
Nitrogen is a critical nutrient that is generally used
and reused by plants within natural ecosystems, with
minimal "leakage" into surface or ground water, where
nitrogen concentrations remain very low (Vitousek et al.,
2002). When nitrogen is applied to the land in amounts
greater than can be incorporated into crops or lost to the
atmosphere through volatilization or denitrification, how-
ever, nitrogen concentrations in streams can increase. The
major sources of excess nitrogen in predominantly agri-
cultural -watersheds are fertilizer and animal waste; other
sources include septic systems and atmospheric deposition.
The total nitrogen concentration in streams consists of
nitrate, the most common bioavailable form; organic nitro-
gen, which is generally less available to biota; and nitrite
and ammonium compounds, which are typically present
at relatively low levels except in highly polluted situations.
Excess nitrate is not toxic to aquatic life, but increased
nitrogen may result in overgrowth of algae, which can
decrease the dissolved oxygen content of the water, thereby
harming or killing fish and other aquatic species (U.S.
EPA, 2005). Excess nitrogen also can lead to problems in
downstream coastal waters, as discussed further in the N
and P Loads in Large Rivers indicator (p. 3-17).
Phosphorus also is an essential nutrient for all life forms,
but at high concentrations the most biologically active form
of phosphorus (orthophosphate) can cause water quality
problems by overstimulating the growth of algae. In addi-
tion to being visually unappealing and causing tastes and
odors in water supplies, excess algal growth can contribute
to the loss of oxygen needed by fish and other animals.
Elevated levels of phosphorus in streams can result from
fertilizer use, animal wastes and wastewater, and the use of
phosphate detergents. The fraction of total phosphorus not
in the orthophosphate form consists of organic and mineral
phosphorus fractions whose bioavailability varies widely.
This indicator reports nitrogen and phosphorus concen-
trations in stream water samples collected from 1992 to
2001 by the U.S. Geological Survey's (USGS's) National
Water Quality Assessment (NAWQA) program, which
surveys the condition of streams and aquifers in study
units throughout the contiguous U.S. Specifically, this
indicator reflects the condition of 129 to 133 streams
draining -watersheds -where agriculture is the predominant
land use (the exact number of sites -with available data
depends on the analyte), according to criteria outlined in
Mueller and Spahr (2005). These -watersheds are located
in 36 of the 51 NAWQA study units (i.e., major river
basins). Sites -were chosen to avoid large point sources
of nutrients (e.g., -waste-water treatment plants). At each
stream site, samples -were collected 12 to 25 times each
year over a l-to-3-year period; this indicator is based on
a flow-weighted annual average of those samples. Related
Exhibit 3-8. Nitrogen in streams in agricultural
watersheds of the contiguous U.S., 1992-2001at
100
A. Nitrate (as N) B. Total nitrogen
60
40
20
0
22.3
17.7
36.2
10.8
13.1
5.3
16.5
46.6
9.8
Concentration:
D <1 mg/L
D 1 to <2
mg/L
D 2 to <6
mg/L
D6to<10
mg/L
D ^10 mg/L
Coverage: Nitrate data from 130 stream sites; total nitrogen data
from 133 stream sites. Stream sites are in watersheds where
agriculture is the predominant land use. These watersheds are
within 36 major river basins studied by the USGS NAWQA
program.
bTotals may not add to 100% due to rounding.
Data source: Mueller and Spahr, 2005
indicators report the concentrations of nitrogen and
phosphorus in small wadeable streams, regardless of land
use (p. 3-13), and nitrate concentrations in ground -water
in agricultural -watersheds (p. 3-15).
For nitrogen, the indicator reports the percentage of
streams -with average concentrations of nitrate and total
nitrogen in one of five ranges: less than 1 milligram per liter
(mg/L); 1-2 mg/L; 2-6 mg/L; 6-10 mg/L; and 10 mg/L or
more. This indicator measures nitrate as N, i.e., the frac-
tion of the material that is actually nitrogen. Measurements
actually include nitrate plus nitrite, but because concentra-
tions of nitrite are typically insignificant relative to nitrate,
this mixture is simply referred to as nitrate. Naturally
occurring levels of nitrate and total nitrogen vary substan-
tially across the country, and statistical analyses of-water
quality data suggest that appropriate reference levels range
from 0.12 to 2.2 mg/L total N, such that some streams in
the lowest category (less than 1 mg/L) may still exceed rec-
ommended -water quality criteria (U.S. EPA, 2002).
Concentrations of total phosphorus and orthophosphate
(as P) are reported in four ranges: less than 0.1 mg/L, 0.1-0.3
mg/L, 0.3-0.5 mg/L, and 0.5 mg/L or more. There is cur-
rently no national -water quality criterion for either form to
protect surface -waters because the effects of phosphorus vary
by region and are dependent on physical factors such as the
EPA's 2008 Report on the Environment
3-15
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INDICATOR
Nitrogen and Phosphorus in Streams in Agricultural
Watersheds (continued)
Exhibit 3-9. Phosphorus in streams in
agricultural watersheds of the contiguous U.S.,
1992-2001ab
100
A. Orthophosphate B. Total phosphorus
(asP)
60
40
20
54.5
40.9
15.5
46.5
24.8
13.2
Concentration:
D <0.1 mg/L
D 0.1 to<0.3
mg/L
D 0.3to<0.5
mg/L
D ^0.5 mg/L
Coverage: Orthophosphate data from 132 stream sites; total
phosphorus data from 129 stream sites. Stream sites are in
watersheds where agriculture is the predominant land use.
These watersheds are within 36 major river basins studied by
the USGSNAWQA prog ram.
bTotals may not add to 100% due to rounding.
Data source: Mueller and Spahr, 2005
size, hydrology, and depth of rivers and lakes. Nuisance algal
growths are not uncommon in rivers and streams below
the low reference level (0.1 mg/L) for phosphorus in this
indicator, however (Dodds and Welch, 2000), and statisti-
cal analyses of water quality data suggest that more appro-
priate reference levels for total P range from 0.01 to 0.075
mg/L, depending on the ecoregion (U.S. EPA, 2002). Some
streams in the lowest category may exceed these recom-
mended water quality criteria.
What the Data Show
Average flow-weighted nitrate concentrations were 2 mg/L
or above in about 60 percent of stream sites in these pre-
dominantly agricultural -watersheds (Exhibit 3-8). About
13 percent of stream sites had nitrate concentrations of at
least 10 mg/L (the slightly smaller percentage of streams
•with total N above 10 mg/L is an artifact of the flow-
weighting algorithm). Nearly half of the streams sampled
had total nitrogen concentrations in the 2-6 mg/L range,
and 78 percent had concentrations of 2 mg/L or above.
Nearly half of the streams in agricultural -watersheds
had average annual flow-weighted concentrations of
Orthophosphate (as P) of at least 0.1 mg/L (Exhibit 3-9).
Approximately 85 percent of the streams had concentra-
tions of total phosphorus of 0.1 mg/L or above, while 13
percent had at least 0.5 mg/L total phosphorus.
Indicator Limitations
• These data represent streams draining agricultural -water-
sheds in 36 of the major river basins (study units) sampled
by the NAWQA program in the contiguous U.S. While
they -were chosen to be representative of agricultural
•watersheds across the United States, they are the result
of a targeted sample design, and may not be an accurate
reflection of the distribution of concentrations in all
streams in agricultural -watersheds in the U.S.
• This indicator does not provide information about trends
over time, as the NAWQA program has completed only
one full sampling cycle to date. Completion of the next
round of sampling -will allow trend analysis, using the
data presented here as a baseline.
Data Sources
Summary data for this indicator -were provided by USGS's
NAWQA program. These data have been published in
Mueller and Spahr (2005), along -with the individual sam-
pling results on -which the analysis is based.
References
Dodds, W.K., andE. Welch. 2000. Establishing nutrient
criteria in streams.]. No. Am. Benthol. Soc. 19:186-196.
Mueller, O.K., and N.E. Spahr. 2005. Water-quality,
streamflow, and ancillary data for nutrients in streams and
rivers across the nation, 1992-2001: U.S. Geological Sur-
vey data series 152.
U.S. EPA (United States Environmental Protection
Agency). 2005. National estuary program—challenges
facing our estuaries. Key management issues: Nutrient
overloading.
U.S. EPA. 2002. Summary table for the nutrient criteria
documents. Accessed November 2007.
Vitousek, P., H. Mooney, L. Olander, and S. Allison. 2002.
Nitrogen and nature. Ambio 31:97-101.
3-16
EPA's 2008 Report on the Environment
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INDICATOI
Nitrogen and Phosphorus Loads in Large Rivers
Nitrogen is a critical nutrient for plants and animals,
and terrestrial ecosystems and head-water streams have
a considerable ability to capture nitrogen or to reduce it
to N2 gas though the process of denitrification. Nitrogen
cycling and retention is thus one of the most important
functions of ecosystems (Vitousek et al., 2002). When
loads of nitrogen from fertilizer, septic tanks, and atmo-
spheric deposition exceed the capacity of terrestrial systems
(including croplands), the excess may enter surface waters,
•where it may have "cascading" harmful effects as it moves
downstream to coastal ecosystems (Galloway and Cowl-
ing, 2002). Other sources of excess nitrogen include direct
discharges from storm water or treated wastewater. This
indicator specifically focuses on nitrate, which is one of the
most bioavailable forms of nitrogen in bodies of water.
Phosphorus is a critical nutrient for all forms of life, but
like nitrogen, phosphorus that enters the environment from
anthropogenic sources may exceed the needs and capacity
of the terrestrial ecosystem. As a result, excess phosphorus
may enter lakes and streams. Because phosphorus is often
the limiting nutrient in these bodies of water, an excess may
contribute to unsightly algal blooms, which cause taste and
odor problems and deplete oxygen needed by fish and other
aquatic species. In some cases, excess phosphorus can com-
bine \vith excess nitrogen to exacerbate algal blooms (i.e., in
situations where algal growth is co-limited by both nutri-
ents), although excess nitrogen usually has a larger effect
downstream in coastal -waters. The most common sources of
phosphorus in rivers are fertilizer and wastewater, includ-
ing storm \vater and treated -waste-water discharged directly
into the river. In most -watersheds, the atmosphere is not an
important source or sink for phosphorus.
This indicator tracks trends in nitrate and phosphorus
loads carried by four of the largest rivers in the United
States: the Mississippi, Columbia, St. Lawrence, and Susque-
hanna. While not inclusive of the entire nation, these four
rivers account for approximately 55 percent of all fresh-water
flow entering the ocean from the contiguous 48 states, and
have a broad geographical distribution. This indicator relies
on stream flow and -water-quality data collected by the U.S.
Geological Survey (USGS), -which has monitored nutrient
export from the Mississippi River since the mid-1950s and
from the Susquehanna, St. Lawrence, and Columbia Rivers
since the 1970s. Data -were collected near the mouth of each
river except the St. Lawrence, -which -was sampled near the
point -where it leaves the United States.
At the sites for -which data are included in this indica-
tor, USGS recorded daily -water levels and volumetric
discharge using permanent stream gauges. Water quality
samples -were collected at least quarterly over the period
of interest, in some cases up to 15 times per year. USGS
calculated annual nitrogen load from these data using
regression models relating nitrogen concentration to dis-
charge, day-of-year (to capture seasonal effects), and time
Exhibit 3-10. Nitrate loads in four major
U.S. rivers, 1955-20043
2,500
2010
aMost measurements include
nitrate plus nitrite, but because
concentrations of nitrite are
typically insignificant relative to
nitrate, this mixture is simply
called "nitrate."
Data source: USGS, 2007a
1980 1990 2000 2010
Year
Areas drained by these
four rivers
Columbia
St. Lawrence
Mississippi
V)
Susquehanna
(to capture any trend over the period). These models -were
used to make daily estimates of concentrations, -which -were
multiplied by the daily flow to calculate the daily nutrient
load (Aulenbach, 2006; Heinz Center, 2005). Because data
on forms of nitrogen other than nitrate and nitrite are not
as prevalent in the historical record, this indicator only uses
measurements of nitrate plus nitrite. As nitrite concentra-
tions are typically very small relative to nitrate, this mix-
ture is simply referred to as nitrate.
EPA's 2008 Report on the Environment
3-17
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INDICATOR
Nitrogen and Phosphorus Loads in Large Rivers (continued)
Exhibit 3-11. Total phosphorus loads in four
major U.S. rivers, 1971-2004
250
200
150
100
50
2010
25
20
15
10
Detail
0
1970 1980
1990
Year
2000
2010
Areas drained by these
four rivers
/
Mississipp
Susquehanna
Data source: USGS, 2007a
What the Data Show
The Mississippi River, which drains more than 40 percent
of the area of the contiguous 48 states, carries roughly 15
times more nitrate than any other U.S. river. Nitrate load
in the Mississippi increased noticeably over much of the last
half-century, rising from 200,000-500,000 tons per year in
the 1950s and 1960s to an average of about 1,000,000 tons
per year during the 1980s and 1990s (Exhibit 3-10). Large
year-to-year fluctuations are also evident. The Mississippi
drains the agricultural center of the nation and contains
a large percentage of the growing population, so it may
not be surprising that the -watershed has not been able to
assimilate all the nitrogen from sources such as crop and
lawn applications, animal manure and human wastes, and
atmospheric deposition (e.g., Rabalais and Turner, 2001).
The Columbia River's nitrate load increased to almost
twice its historical loads during the later half of the 1990s, but
by the last year of record (2002), the nitrate load had returned
to levels similar to those seen in the late 1970s (Exhibit 3-10).
The St. Lawrence River showed an overall upward trend in
nitrate load over the period of record, while the Susquehanna
does not appear to have shown an appreciable trend in either
direction. Over the period of record, the Columbia and St.
Lawrence carried an average of 67,000 and 66,000 tons of
nitrate per year, respectively, while the Susquehanna averaged
46,000 tons. By comparison, the Mississippi carried an aver-
age of 772,000 tons per year over its period of record.
The total phosphorus load decreased in the St. Lawrence
and Susquehanna Rivers over the period of record (Exhibit
3-11). There is no obvious trend in the Mississippi and
Columbia Rivers, and the year-to-year variability is quite
large. Nitrogen and phosphorus loads tend to be substan-
tially higher during years of high precipitation, because of
increased erosion and transport of the nutrients to stream
channels (Smith et al., 2003). Over the full period of
record, average annual phosphorus loads for the Mississippi,
Columbia, St. Lawrence, and Susquehanna were 138,000;
11,000; 6,000; and 3,000 tons, respectively.
Indicator Limitations
• The indicator does not include data from numerous
coastal -watersheds -whose human populations are rapidly
increasing (e.g., Valigura et al., 2000).
• It does not include smaller -watersheds in geologically
sensitive areas, -whose ability to retain nitrogen might be
affected by acid deposition (e.g., Evans et al., 2000).
• It does not include forms of nitrogen other than nitrate.
Although nitrate is one of the most bioavailable forms of
nitrogen, other forms may constitute a substantial por-
tion of the nitrogen load. Historically, nitrate data are
more extensive than data on other forms of nitrogen.
• Not all forms of phosphorus included in the total phos-
phorus loads are equally capable of causing algal blooms.
3-18
EPA's 2008 Report on the Environment
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INDICATOI
Nitrogen and Phosphorus Loads in Large Rivers (continued)
Data Sources
Data were compiled for EPA by USGS (USGS, 2007a),
•which provided a similar analysis to the Heinz Center for
its updated report. Nutrient loads for the Columbia, St.
Lawrence, and Susquehanna were originally reported in
Aulenbach (2006); portions of the Mississippi analysis were
previously published in Goolsby et al. (1999), while other
portions have not yet been published. Underlying nutrient
sampling and daily stream flow data can be obtained from
USGS's public databases (USGS, 2007b,c).
References
Aulenbach, B.T. 2006. Annual dissolved nitrite plus nitrate
and total phosphorus loads for Susquehanna, St. Lawrence,
Mississippi-Atchafalaya, and Columbia River Basins,
1968-2004. USGS Open File Report 06-1087.
Evans, C.D., A. Jenkins, and R.F. Wright. 2000. Surface
•water acidification in the South Pennines I. Current status
and spatial variability. Environ. Pollut. 109(1):11-20.
Galloway, J., and E. Cowling. 2002. Reactive nitrogen and
the \vorld: 200 years of change. Ambio 31:64-71.
Goolsby, D.A., W.A. Battaglm, G.B. Lawrence, R.S.
Artz, B.T. Aulenbach, R.P. Hooper, D.R. Keeney, and
GJ. Stensland. 1999. Flux and sources of nutrients in
the Mississippi-Atchafalaya River Basin—topic 3 report
for the integrated assessment on hypoxia in the Gulf of
Mexico. NOAA Coastal Ocean Program Decision Analy-
sis Series No. 17.
Heinz Center (The H. John Heinz III Center for Sci-
ence, Economics, and the Environment). 2005. The state
of the nation's ecosystems: Measuring the lands, -waters,
and living resources of the United States. New York, NY:
Cambridge University Press. Web update 2005:
Rabalais, N.N., and R.E. Turner, eds. 2001. Coastal
hypoxia: Consequences for living resources and ecosys-
tems. Coastal and estuarine studies 58. Washington, DC:
American Geophysical Union.
Smith, S.V., D.P. Swaney, L. Talaue-McManus, J.D.
Bartley, P.T Sandhei, CJ. McLaughlm, V.C. Dupra,
C.J. Grassland, RW. Buddemeier, B.A. Maxwell, and F.
Wulff. 2003. Humans, hydrology, and the distribution
of inorganic nutrient loading to the ocean. BioScience
53:235-245.
USGS (United States Geological Survey). 2007a. Data
provided to ERG (an EPA contractor) by Nancy Baker,
USGS. September 12, 2007.
USGS. 2007b. National Stream Quality Accounting Net-
work (NASQAN) data. Accessed 2007.
USGS. 2007c. National Water Information System.
Accessed 2007.
Valigura, R., R. Alexander, M. Castro, T Meyers, H.
Paerl, P. Stacey, and R. Turner, eds. 2000. Nitrogen load-
ing in coastal -water bodies—an atmospheric perspective.
Washington, DC: American Geophysical Union.
Vitousek, P., H. Mooney, L. Olander, and S. Allison. 2002.
Nitrogen and nature. Ambio 31:97-101.
INDICATOI
Pesticides in Streams in Agricultural Watersheds
Pesticides are chemicals or biological agents that kill
plant or animal pests and may include herbicides,
insecticides, fungicides, and rodenticides. More than
a billion pounds of pesticides (measured as pounds of
active ingredient) are used in the United States each
year to control -weeds, insects, and other organisms that
threaten or undermine human activities (Aspelin, 2003).
About 80 percent of the total is used for agricultural pur-
poses. Although pesticide use has resulted in increased
crop production and other benefits, pesticide contamina-
tion of streams, rivers, lakes, reservoirs, coastal areas, and
ground -water can cause unintended adverse effects on
aquatic life, recreation, drinking -water, irrigation, and
other uses. Water also is one of the primary path-ways by
•which pesticides are transported from their application
areas to other parts of the environment (USGS, 2000).
This indicator is based on stream -water samples collected
between 1992 and 2001 as part of the U.S. Geological
Survey's (USGS's) National Water Quality Assessment
(NAWQA) program, -which surveys the condition of
streams and aquifers in study units throughout the contigu-
ous United States. Of the streams sampled for pesticides,
this indicator focuses on 83 streams in -watersheds -where
agriculture represents the predominant land use, accord-
ing to criteria outlined in Gilliom et al. (2007). These 83
streams are located in 36 of the 51 NAWQA study units
(i.e., major river basins). From each site, NAWQA col-
lected 10 to 49 -water samples per year over a l-to-3-year
EPA's 2008 Report on the Environment
3-19
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INDICATOR
Pesticides in Streams in Agricultural Watersheds (continued)
period to analyze for 75 different pesticides and eight
pesticide degradation products, which together account for
approximately 78 percent of the total agricultural pesticide
application in the United States by weight during the study
period (Gilliom et al., 2007). This indicator reports on two
variables: (1) the number of stream sites in which pesticides
or degradation products were detected and (2) the number
of stream sites where the annual time-weighted average
concentration of one or more of these compounds exceeds
standards for aquatic life. A related indicator discusses
pesticide concentrations in ground water in agricultural
watersheds (p. 3-19).
Several types of water quality benchmarks for aquatic life
•were used. Where available, data were compared with EPA's
acute and chronic ambient water-quality criteria for the
protection of aquatic life (AWQC-ALs). The acute AWQC-
AL is the highest concentration of a chemical to which an
aquatic community can be exposed briefly without result-
ing in an unacceptable effect. The chronic AWQC-AL
is the highest concentration to which an aquatic com-
munity can be exposed indefinitely without resulting in
an unacceptable effect. An exceedance was identified if a
single sample exceeded the acute AWQC-AL or if a 4-day
moving average exceeded the chronic AWQC-AL (per
EPA's definition of the chronic AWQC-AL). Results were
also compared with aquatic life benchmarks derived from
toxicity values presented in registration and risk-assessment
documents developed by EPA's Office of Pesticide Pro-
grams. These benchmarks included acute and chronic
values for fish and invertebrates, acute values for vascular
and nonvascular plants, and a value for aquatic community
effects. An exceedance was identified if a single sample
exceeded any acute benchmark or if the relevant moving
average exceeded a chronic benchmark. Altogether, aquatic
life benchmarks were available for 62 of the pesticides and
degradation products analyzed. More information about the
derivation and application of aquatic life guidelines for this
indicator can be found in Gilliom et al. (2007).
What the Data Show
Of the streams sampled, all had at least one pesticide detec-
tion and 86 percent had five or more compounds present,
•which suggests that pesticides frequently occur as mixtures
(Exhibit 3-12). In 57 percent of the streams sampled, at
least one pesticide was detected at a concentration that
exceeded one or more aquatic life benchmarks (Exhibit
3-12). Approximately 7 percent of the streams (six of the
83 streams sampled) had five or more pesticides at concen-
trations above aquatic life benchmarks.
Indicator Limitations
• These data represent streams draining agricultural -water-
sheds in 36 of the study units (major river basins) sampled
by the NAWQA program in the contiguous United
Exhibit 3-12. Pesticides in streams in
agricultural watersheds of the contiguous U.S.,
1992-2001ab
100
A. Compounds B. Exceedances
detected0 of aquatic life
benchmarks
3fi
10.8
85.5
43.4
37.3
12.0
7.2
Number of
compounds:
DO
D1or2
D3or4
• 5 or more
60
40
20
Coverage: 83 stream sites in watersheds where agriculture is the
predominant land use. These watersheds are within 36 major
river basins studied by the USGS NAWQA program.
bTotals may not add to 100% due to rounding.
=AII streams had at least one compound detected.
Data source: Gilliom et al., 2007
States. While they were chosen to be representative of
agricultural -watersheds across the nation, they are the
result of a targeted sampling design, and may not be an
accurate reflection of the distribution of concentrations
in all streams in the nation's agricultural -watersheds.
• This indicator does not provide information about trends
over time, as the NAWQA program has completed only
one full sampling cycle to date. Completion of the next
round of sampling -will allow trend analysis, using the
data presented here as a baseline.
• Aquatic life benchmarks do not currently exist for 21
of the 83 pesticides and pesticide degradation prod-
ucts analyzed. Current standards and guidelines do not
account for mixtures of pesticide chemicals and seasonal
pulses of high concentrations.
• The pesticide benchmarks used here are designed to be
fully protective of aquatic health. Other indicators, such
as Coastal Sediment Quality (p. 3-42), use aquatic life
thresholds that are less protective. Thus, these indicators
are not necessarily comparable to one another.
• This indicator does not provide information on the mag-
nitude of pesticide concentrations, only -whether they
exceed or fall below benchmarks.
3-20
EPA's 2008 Report on the Environment
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INDICATOI
Pesticides in Streams in Agricultural Watersheds
Data Sources
Summary data for this indicator were provided by USGS's
NAWQA program, based on supporting technical data
published in conjunction with Gilliom et al. (2007). Over-
all pesticide occurrence was determined from individual
site results in Appendix 6 of Gilliom et al. (2007) (http://
•water, usgs.gov/nawqa/pnsp/pubs/circl 291 /appendix6/),
•while exceedances were calculated from a separate sup-
porting data file (http://water.usgs.gov/nawqa/pnsp/pubs/
circ!291/figures/descriptions/6_05_exceeddata.txt).
References
Aspelin, A.L. 2003. Pesticide usage in the United States:
Trends during the 20th century. Raleigh, NC: Center for
Integrated Pest Management, North Carolina State Univer-
sity.
Gilliom, R.J., J.E. Barbash, C.G. Crawford, P.A. Hamil-
ton, J.D. Martin, N. Nakagaki, L.H. Nowell, J.C. Scott,
P.E. Stackelberg, G.P. Thelm, and D.M. Wolock. 2007.
Pesticides in the nation's streams and ground water,
1992-2001. U.S. Geological Survey circular 1291. Revised
February 15, 2007. (document); (sup-
porting technical information)
USGS (United States Geological Survey). 2000. Pesticides
in stream sediment and aquatic biota.
Benthic Macro in vertebrates in Wadeable Streams
Freshwater benthic macroinvertebrate communities are
composed primarily of insect larvae, mollusks, and
•worms. They are an essential link in the aquatic food
•web, providing food for fish and consuming algae and
aquatic vegetation (U.S. EPA, 2006b). The presence and
distribution of macroinvertebrates in streams can vary
across geographic locations based on elevation, stream
gradient, and substrate (Barbour et al., 1999). These
organisms are sensitive to disturbances in stream chemis-
try and physical habitat, both in the stream channel and
along the riparian zone, and alterations to the physical
habitat or water chemistry of the stream can have direct
and indirect impacts on their community structure.
Because of their relatively long life cycles (approximately
1 year) and limited migration, benthic macroinvertebrates
are particularly susceptible to site-specific stressors (Bar-
bour et al., 1999).
This indicator is based on data collected for EPA's Wade-
able Streams Assessment (WSA). Wadeable streams are
streams, creeks, and small rivers that are shallow enough
to be sampled using methods that involve wading into the
•water. They typically include waters classified as 1st through
4th order in the Strahler Stream Order classification system
(Strahler, 1952). Between 2000 and 2004, crews sampled
1,392 sites throughout the contiguous U.S. using standard-
ized methods (U.S. EPA, 2004a,b). Sites were sampled
between mid-April and mid-November. At each site, a
composite bottom sample was collected from eleven equally
spaced transects within the sample reach. The WSA is based
on a probabilistic design, so results from the sample sites
can be used to make statistically valid statements about the
percentage of wadeable stream miles that fall above or below
reference values for the indicator.
For this analysis, the 48 contiguous states were divided
into nine broad ecoregions (U.S. EPA, 2006b), which were
defined by the WSA based on groupings of EPA Level III
ecoregions (Omermk, 1987; U.S. EPA, 2007). Benthic
community condition was determined using two dif-
ferent approaches, each reflecting a distinct aspect of the
indicator: an Index of Biological Integrity (IBI) and an
observed/expected (O/E) predictive model.
The IBI is an index that reduces complex information
about community structure into a simple numerical value
based on measures of taxonomic richness (number of taxa);
taxonomic composition (e.g., insects vs. non-insects); taxo-
nomic diversity; feeding groups (e.g., shredders, scrapers,
or predators); habits (e.g., burrowing, clinging, or climbing
taxa); and tolerance to stressors. Separate metrics were used
for each of these categories in the nine WSA ecoregions,
based on their ability to best discriminate among streams.
Each metric was scaled against the 5th-95th percentiles for
the streams in each region to create an overall IBI, whose
value ranges from 0 to 100 (Stoddard et al., 2005).
Once the overall IBI was established, a set of relatively
undisturbed sites was selected in order to determine the
range of IBI scores that would be expected among "least
disturbed" sites. A separate reference distribution was
developed for each ecoregion. Next, the IBI score for every
EPA's 2008 Report on the Environment
3-21
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INDICATOR
Benthic Macro in vertebrates in Wadeable Streams (continued)
Exhibit 3-13. Index of Biological Integrity (IBI) for
benthic macroinvertebrates in wadeable streams
of the contiguous U.S., by region, 2000-2004ab
IBI score:
Least
disturbed
Moderately
disturbed
Most
disturbed
Not assessed/
no data
18.2
20.4
51.8
9.5
Percent of stream miles in each category:
Eastern
Highlands
Plains and
Lowlands
West
All U.S.
29.0
29.0
40.0
45.1
25.9
27.4
28.2
24.9
41.9
2.0
1.7
5.0
aRegions based on groupings of
EPA Level III ecoregions
(Omernik, 1987; U.S. EPA,
2007).
bTotalsmaynotaddto100%
due to rounding.
Data source: U.S. EPA, 2006b
Regions
Eastern
West "V ""V Highlands
Plains and Lowlands
sampled site was compared to the distribution of IBI scores
among the ecoregion's reference sites. If a site's IBI score
\vas below the 5th percentile of the regional reference dis-
tribution, the site was classified as "most disturbed." This
threshold was used because it offers a high degree of con-
fidence that the observed condition is statistically different
from the "least disturbed" reference condition. Streams
•with IBI scores above the 25th percentile of the reference
range were labeled "least disturbed," indicating a high
probability that they are similar to the relatively undis-
turbed reference sites. Streams falling between the 5th and
25th percentiles were classified as "moderately disturbed."
In addition to national totals, this indicator displays IBI
scores for three broad regions, which are composed of mul-
tiple WSA ecoregions and which share major climate and
landform characteristics (U.S. EPA, 2006b).
The O/E predictive model compares the actual number
of macroinvertebrate taxa observed at each WSA site (O)
•with the number expected (E) to be found at a site that is
in minimally disturbed condition (Armitage, 1987). First,
reference sites were divided into several groups based on
the observed benthic assemblages, and the probability of
observing each taxon in each group of sites was deter-
mined. Next, a multivariate model was used to character-
ize each group of reference sites in terms of their shared
physical characteristics (variables that are largely unaffected
by human influence, such as soil type, elevation, and lati-
tude). This predictive model then was applied to each test
site to determine which group (s) of reference sites it should
be compared to. For each test site, the "expected" proba-
bility of observing each taxon was calculated as a -weighted
average based on the probability of observing that taxon in
a particular group of reference sites and the probability that
the test site is part of that particular group of sites, based on
physical characteristics. The total "E" for the test site was
generated by adding the probabilities of observing each of
the individual taxa. The actual number of taxa collected at
the site (O) was divided by "E" to arrive at an O/E ratio
(Hawkins et al, 2000; Hawkins and Carlisle, 2001). An
O/E of 1.0 means the site's taxa richness is equal to the
average for the reference sites. Each tenth of a point below
1 suggests a 10 percent loss of taxa.
What the Data Show
Based on the IBI, slightly more than one-quarter of-wade-
able stream miles nation-wide (28.2 percent) -were classified as
"least disturbed" -with respect to benthic macroinvertebrate
condition, -while 41.9 percent -were in the "most disturbed"
category (Exhibit 3-13). Of the three major stream regions
in the nation (see the inset map, Exhibit 3-13), the eastern
highlands had the lowest percentage of "least disturbed"
stream miles (18.2 percent), -while the -western region had
the highest percentage (45.1 percent).
Because there are no agreed-upon thresholds for the O/E
model, the results are presented in 20 percent increments of
taxa losses for the contiguous 48 states (Exhibit 3-14). Nearly
40 percent (38.6 percent) of wadeable stream miles have lost
more than 20 percent of their macroinvertebrate taxa, com-
pared to comparable minimally disturbed reference sites, and
8.3 percent of stream miles have lost more than 60 percent
of their macroinvertebrate taxa.
Indicator Limitations
• Although the probability sampling design results in
unbiased estimates for the IBI and O/E in wadeable
streams during the April-November index period, values
may be different during other seasons.
• Reference conditions for the IBI and O/E vary from one
ecoregion to another in both number and quality, -which
limits the degree of ecoregional resolution at -which this
indicator can be calculated.
• Because "E" is subject to both model error and sam-
pling error, O/E values near 1.0 (above or below) do not
necessarily imply a gain or loss of species relative to the
reference conditions.
• Trend data are unavailable because this is the first time
that a survey on this broad scale has been conducted, and
the survey design does not allow trends to be calculated
3-22
EPA's 2008 Report on the Environment
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INDICATOI
Benthic Macro in vertebrates in Wadeable Streams (continued)
Exhibit 3-14. Percent loss of benthic
macroinvertebrate taxa in wadeable streams of
the contiguous U.S., relative to the number of
expected taxa, 2000-2004ab
100
60
40
20
1-8.
7.4
28.8
25.3
18.4
11.9
^ 6.5
D Not assessed/no data
D No loss
D 0-20% loss
• 20-40% loss
D 40-60% loss
D 60-80% loss
D More than 80% loss
aNumber of expected taxa based
on minimally disturbed
reference sites.
"Totals may not add to 100% due
to rounding.
Data source: U.S. EPA, 2005
\vithin a single sampling period (2000-2004). These data
•will serve as a baseline for future surveys.
Data Sources
The results shown in Exhibit 3-13 were previously published
in EPA's 2006 Wadeable Streams Assessment (WSA) report
(U.S. EPA, 2006b). The data in Exhibit 3-14 are based on
frequency distributions provided by the WSA program (U.S.
EPA, 2005) (U.S. EPA [2006b] also presents results from the
O/E analysis, but using different categories). Data from indi-
vidual stream sites can be obtained from EPA's STORET
database (U.S. EPA, 2006a) (http://www.epa.gov/owow/
streamsurvey/web_data.html).
References
Armitage, D. 1987. The prediction of the macroinver-
tebrate fauna of unpolluted running-water sites in Great
Britain using environmental data. Freshwater Biol.
17:41-52.
Barbour, M.T., J. Gerritson, B.D. Snyder, andJ.B. Stribling.
1999. Rapid bioassessment protocols for use in streams and
•wadeable rivers: Periphyton, benthic macroinvertebrates and
fish. Second edition. EPA/841/B-99/002. Washington, DC:
U.S. Environmental Protection Agency.
Hawkins, C.P., and D.M. Carlisle. 2001. Use of predictive
models for assessing the biological integrity of wetlands and
other aquatic habitats. In: Rader, R.B., and D.P. Batzer,
eds. Bioassessment and management of North American
wetlands. New York, NY: John Wiley & Sons. pp. 59-83.
Hawkins, C.P., R.H. Norris, J.N. Hogue, andJW. Fem-
inella. 2000. Development and evaluation of predictive
models for measuring the biological integrity of streams.
Ecol. Appl. 10:1456-1477.
Omernik, J.M. 1987. Ecoregions of the conterminous
United States. Map (scale 1:7,500,000). Ann. Assoc. Am.
Geog. 77(1):118-125.
Stoddard, J., D.V. Peck, S.G. Paulsen,]. Van Sickle, C.P.
Hawkins, A.T. Herlihy, R.M. Hughes, F. Wright, P.R.
Kaufmann, D.P. Larsen, G. Lomnicky, A.R. Olsen,
S.A. Peterson, P.L. Rmgold, and T.R. Whittier. 2005.
An ecological assessment of western streams and rivers.
EPA/620/R-05/005. Washington, DC: U.S. Environmen-
tal Protection Agency,
Strahler, A.N. 1952. Dynamic basis of geomorphology.
Geol. Soc. Am. Bull. 63:923-938.
U.S. EPA (United States Environmental Protection
Agency). 2007. Level III ecoregions of the conterminous
United States. Accessed November 2007.
U.S. EPA. 2006a. Data from the Wadeable Streams
Assessment. Accessed 2006.
U.S. EPA. 2006b. Wadeable Streams Assessment: A collab-
orative survey of the nation's streams. EPA/841/B-06/002.
U.S. EPA. 2005. Data provided to ERG (an EPA contrac-
tor) by Susan Holdsworth, EPA. December 2005.
U.S. EPA. 2004a. Wadeable streams assessment: Benthic
laboratory methods. EPA/841/B-04/007.
U.S. EPA. 2004b. Wadeable streams assessment: Field opera-
tions manual. EPA/841/B-04/004.
EPA's 2008 Report on the Environment
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3.2.3 Discussion
What These Indicators Say About Trends in
the Extent and Condition of Fresh Surface
Waters and Their Effects on Human Health
and the Environment
Although the indicators do not characterize the extent of all
fresh surface waters, they do provide information about flow
patterns in streams. As the Stream Flows indicator (p. 3-8)
shows, substantial shifts in the volume of high and low flows
have occurred over time, with large fluctuations between rela-
tively "•wet" and "dry" periods. In general, since the 1960s,
more streams have experienced increases in base flow volume
than have experienced decreases, compared to the prior 20
years. At the same time, overall flow variability appears to
have decreased somewhat. These shifts are particularly impor-
tant in intermittent streams, where life forms may be quite
sensitive to changes in patterns of flow and no flow. Although
intermittent streams can be found throughout the country, the
Stream Flows indicator focuses on those that occur in grass-
land and shrubland areas, many of which are arid or semi-arid
and thus especially sensitive to water stress. As this indicator
shows, no-flow periods have generally decreased in number
and duration since the 1960s, although a few grassland/
shrubland streams have experienced substantial increases.
Factors that influence stream flow can include weather and cli-
mate, land cover, hydromodifications such as dams, and water
withdrawals. Decreases in flow volume were somewhat less
prevalent within a subset of relatively unmodified "reference"
streams. Nonetheless, trends in the "reference" streams were
highly similar to trends in the general population of streams
overall, suggesting that dams, diversions, and land cover
changes are not the major causes of the observed changes in
stream flow over the last half-century.
The physical condition of lakes and streams is in part a func-
tion of the interaction between sediment and water. As the
Streambed Stability indicator (p. 3-11) shows, about one-
fourth of the nation's wadeable streams show significant
evidence of excess fine sediments, which can diminish habitat.
In some cases, excess sedimentation can reflect the influence of
human stressors like erosion. Excess sedimentation also can be
a symptom of broader changes in physical condition, such as
hydromodifications that alter flow and sediment transport.
The ROE indicators provide a mixed picture of the chemi-
cal condition of fresh surface waters. Acidity in lakes and
streams has decreased in three of the four sensitive areas
studied (Lake and Stream Acidity indicator, p. 2-42), while
excess nutrients are present in many streams, ranging from
small wadeable streams to the nation's largest rivers (three
N and P indicators, pp. 3-13, 3-15, and 3-17). In agricul-
tural areas, more than half of monitoring sites have at least
one pesticide at levels that exceed guidelines for aquatic
health (Pesticides in Agricultural Streams indicator, p. 3-19).
These indicators reflect the influence of many stressors. For
example, the two Agricultural Streams indicators (pp. 3-15
and 3-19) demonstrate how chemicals applied to the land can
ultimately affect surface waters. Conversely, efforts to reduce
human stressors can result in improved water condition. For
example, areas with declines in acidity correspond with areas
of decreased acid deposition (Lake and Stream Acidity indi-
cator, p. 2-42), while declining phosphorus loads in at least
one river may be related to detergent bans and improved
sewage treatment (N and P Loads in Large Rivers indicator,
p. 3-17). The indicators also are influenced by natural stres-
sors (e.g., year-to-year variability in nutrient loads due to
variations in precipitation).
One ROE indicator presents direct information on the bio-
logical condition of fresh surface waters. About 40 percent of
the nation's wadeable stream miles exhibit a substantial loss
(more than 20 percent) of macroinvertebrate taxa—approxi-
mately equal to the number of stream miles considered "most
disturbed" when other metrics of benthic community condi-
tion are considered (Benthic Macroinvertebrates in Wade-
able Streams indicator, p. 3-21). Benthic macroinvertebrate
communities are particularly sensitive to physical and chemi-
cal stressors, and thus the condition of these assemblages can
provide information about the extent to which these stressors
may be causing measurable harm. In addition, several other
ROE indicators provide information about stressors that are
known to affect biological condition. For example, the ROE
indicators show a portion of streams with excess sedimenta-
tion, pesticides above aquatic life guidelines, nutrients at levels
that could encourage eutrophication, and substantial changes
in high and low stream flows.
Limitations, Gaps, and Challenges
Although the ROE indicators provide valuable information
about the extent and condition of fresh surface waters, there
are a few general limitations to their ability to depict trends
over space and time. For example, trends in condition may be
tied to the location and timing of intermittent stressors (e.g.,
pesticide application), so indicators that assess national condi-
tion using samples that are spread out over time and space may
obscure local conditions and extreme events. Some indicators
are also restricted to specific study areas. For example, the two
Agricultural Streams indicators (pp. 3-15 and 3-19) do not
characterize non-agricultural -watersheds, and the Lake and
Stream Acidity indicator (p. 2-42) does not include localized
acidification in the West.
In addition to the challenges inherent in assessing fresh surface
•waters, there are challenges in interpreting what the indicators
say. Ecological responses to freshwater stressors are complex
and may depend on the species that inhabit a particular area.
In some cases—e.g., the three indicators from the Wade-
able Streams Assessment—data must be adjusted to account
for variations in regional reference conditions. It can also be
difficult to link effects to specific stressors, as many indicators
reflect the interplay of multiple human and natural factors. For
example, local bedrock can contribute high levels of nutrients
to some rivers, while precipitation variability can drive trends
in nutrient loads, potentially obscuring trends in anthropo-
genic stressors.
3-24
EPA's 2008 Report on the Environment
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There are no ROE indicators for a few key aspects of the
extent and condition of fresh surface -waters. The folio-wing
information -would help to better answer this question:
• Information on the extent of different types of fresh surface
•waters, stressors to extent (e.g., water usage and extent of
snowpack), and associated effects on ecological systems.
• Nationally consistent information to characterize stressors
to fresh surface water condition—specifically pollutant
loadings from point and nonpoint sources.
• Information on the condition of large rivers. The N and
P Loads in Large Rivers indicator (p. 3-17) describes
nutrient loads at the mouth, but does not address condi-
tions upstream.
• Indicators on the condition of ponds, reservoirs, and lakes,
including the Great Lakes. A nationally consistent indicator
of lake trophic state could bring together several aspects of
condition (e.g., physical, chemical, and biological param-
eters) related to eutrophication—a problem facing many of
the nation's lakes.
• Indicators of salinity, of particular importance in arid
regions.
• Information on the extent and condition of riparian zones
and lake shoreline (the land-water interface), where much
biological activity occurs.
• Information about toxic contaminants in freshwater sedi-
ments. Sediment contaminants can accumulate through the
food web, and may ultimately impact the health of humans
•who consume fish and shellfish.
• Information on the condition offish communities, which
can be affected by many different stressors.
In addition, there are currently no ROE indicators that
explicitly link human health effects to the extent or condition
of fresh surface waters. As described in Chapter 1, this type of
information gap largely reflects the difficulty of determining
exact causation between stressors and effects.
3.3 What Are the Trends
in the Extent and
Condition of Ground
Water and Their Effects
on Human Health
the Environment?
3.3.1 Introduction
A large portion of the -world's fresh water resides underground,
stored within cracks and pores in the rock that makes up the
Earth's crust. The U.S. Geological Survey estimates that there
are approximately 1 million cubic miles of ground water within
one-half mile of the Earth's surface—30 times the volume of
all the -world's fresh surface -waters.2 Many parts of the U.S. rely
heavily on ground -water for human uses (e.g., drinking, irriga-
tion, industry, livestock), particularly areas -with limited pre-
cipitation (e.g., the South-west), limited surface water resources,
or high demand from agriculture and growing populations
(e.g., Florida). Half of the U.S. population (51 percent) relies on
ground -water for domestic uses.3
Ecological systems also rely on ground -water. For example,
some -wetlands and surface -waters are fed by springs and seeps,
•which occur -where a body of ground -water—known as an
aquifer—reaches the Earth's surface. While the contribution
of ground -water to stream flow varies -widely among streams,
hydrologists estimate that the average contribution of ground
•water is 40 to 50 percent in small- and medium-sized streams.
The ground -water contribution to all stream flow in the U.S.
may be as large as 40 percent.4
The extent of ground -water refers to the amount available,
typically measured in terms of volume or saturated thick-
ness of an aquifer. The condition of ground -water reflects a
combination of physical, biological, and chemical attributes.
Physical properties reflect patterns of flow—i.e., the volume,
speed, and direction of ground -water flow in a given location.
Biologically, ground -water can contain a variety of organisms,
including bacteria, viruses, protozoans, and other pathogens.
Ground -water can also contain a variety of chemicals, -which
may occur naturally or as a result of human activities. Chemi-
cals that may occur in ground -water include nutrients, metals,
radionuclides, salts, and organic compounds such as petroleum
products, pesticides, and solvents. These chemicals may be dis-
solved in -water or—in the case of insoluble organic contami-
nants—exist as undissolved plumes.
U.S. Geological Survey. 1999. Ground water (general interest publication).
Reston,VA.
Ibid.
Alley, W.M.T.E. Reilly, and O.L. Franke. 1999. Sustainability of ground-water
resources. Circular 1186. Denver, CO: U.S. Geological Survey.
EPA's 2008 Report on the Environment
3-25
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Many stressors can affect the extent of ground water, includ-
ing patterns of precipitation and snowmelt and human activi-
ties that change or redistribute the amount of ground water
in an aquifer. One major way humans influence ground water
extent is by withdrawing water for drinking, irrigation, or
other uses (e.g., ground water extracted to lower the water
table for mining operations). Other human activities can
increase ground water levels, such as surface irrigation runoff
recharging a shallow aquifer, or water pumped directly into
the ground in order to store surface waters for future use, or
to aid in oil and gas extraction. Human activities can affect
ground water extent indirectly, too; for example, impervi-
ous paved surfaces may prevent precipitation from recharging
ground water. In some cases, changes in ground water extent
may be caused by a combination of these human and natural
factors—for example, droughts that require humans to with-
draw more water from the ground (e.g., for irrigation), while
at the same time providing less precipitation for recharge.
Some aquifers are more susceptible than others to changes in
extent. For example, some deep aquifers may take thousands
of years to recharge, particularly if they lie below highly
impermeable confining layers.
Aquifer depletion—i.e., decreased extent—can adversely affect
the humans and ecosystems that directly or indirectly depend
on ground water. Less ground water available for human or
ecological use can result in lower lake levels or—in extreme
cases—cause perennial streams to become intermittent or
totally dry, thus harming aquatic and riparian plants and
animals that depend on regular surface flows. An area with a
high water table may have plant communities that tap ground
•water directly with their roots, so even a slight lowering of
the aquifer could affect native species—which in turn could
benefit invasive species.5 In addition, lower water table levels
may lead to land subsidence and sinkhole formation in areas
of heavy withdrawal, which can damage buildings, roads, and
other structures and can permanently reduce aquifer recharge
capacity by compacting the aquifer medium (soil or rock).
Finally, changes in the ground water flow regime can lead
to consequences such as salt water intrusion, in which saline
ground water migrates into aquifers previously occupied by
fresh ground water.
Although aquifer depletion can have serious effects, the oppo-
site, far less common problem—too much ground water—can
also be detrimental. Too much ground water discharge to
streams can cause erosion and can alter the balance of aquatic
plant and animal species, as has been reported in association
•with some mining sites.6
Like extent, condition is influenced by both natural sources
and human activities. Some ground water has high levels
of naturally occurring dissolved solids (salinity), or met-
als such as arsenic that can be present as a result of natural
rock formations. Land use can affect the condition of ground
•water; for example, pesticides, fertilizers, and other chemi-
cals applied to the land can leach into ground water, while
•waste from livestock and other animals can contribute con-
taminants such as nutrients, organic matter, and pathogens.
Shallow and unconfined aquifers are particularly susceptible
to this type of contamination. In addition, landfills may
leach metals, solvents, and other contaminants into ground
•water (particularly older landfills that do not have liners and
leachate collection systems). Mining operations can mobi-
lize toxic metals, acidic compounds, and other substances
that can impact the condition of ground water. Finally,
chemical or biological contaminants may enter aquifers as a
result of unintentional releases, including chemical spills on
land, leaks from storage tanks, sewers or septic systems, and
unplugged abandoned wells that allow a direct route of entry
for contaminants.
Stressors that affect ground water condition ultimately affect
the condition of water available for drinking, irrigation, or
other human needs. In some cases, treatment may be needed
to ensure that finished drinking water does not pose risks to
human health. Because drinking water can come from many
different types of water bodies, and because of the many com-
plex issues associated with treatment and regulation of drink-
ing \vater, this topic is addressed in greater detail in its own
section of this report, Section 3.6. The condition of ground
•water also can affect ecological systems. For example, many
fish species depend on cold, clear spring-fed waters for habitat
or spawning grounds.7'8 In some cases, aquifers themselves may
constitute ecosystems. For example, caves and sinkholes are
home to many types of aquatic fauna, including invertebrates
and fish adapted to life underground.9 Ground water can
also affect the condition of other environmental media. For
example, volatile ground water contaminants can potentially
migrate into indoor air via soil vapor intrusion.
In many ways, extent and condition are intertwined. For
example, stressors that affect extent—such as withdrawal or
injection—can also alter physical parameters of the ground
•water flow regime, such as velocity and direction of flow.
These physical alterations can affect patterns of discharge to
surface waters, as well as the movement of water and contami-
nants within the ground (e.g., salt water intrusion).
5 Grantham, C. 1996. An assessment of ecological impacts of ground
water overdraft on wetlands and riparian areas on the United States.
EPA/813/S-96/00I.Washington, DC: U.S. Environmental Protection Agency.
6 United States Department of the Interior. 2002. Hydrologic impacts of min-
ing. Chapter 1. In: Permitting hydrology, a technical reference document for
determination of probable hydrologic consequence (PHC) and cumulative
hydrologic impact assessments (CHIA).Washington, DC. Accessed November
8, 2003.
7 Prichard, D.J.Anderson, C. CorrellJ. Fogg, K. Gebhardt, R. Krapf, S. Leonard,
B. Mitchell, and J. Stasts. 1998. Riparian area management: A user guide to
assessing proper functioning condition and the supporting science for lotic
areas.Technical reference 1737-15. Denver, CO: US. Department of the Inte-
rior, Bureau of Land Management, National Applied Resource Sciences Center.
Boyd, M., and D. Sturdevant. 1997.The scientific basis for Oregon's stream
temperature standard: Common questions and straight answers. Portland, OR:
Oregon Department of Environmental Quality.
Elliott,WR. 1998. Conservation of the North American cave and karst biota.
In:Wilkens, H., D.C. Culver, andWF. Humphreys, eds. Subterranean biota.
Amsterdam, The Netherlands: Elsevier (Ecosystems of the World series), pp.
665-689. Preprint online at
3-26
EPA's 2008 Report on the Environment
-------
3.3.2 ROE Indicators
This report presents an indicator of ground water condition
based on a nation-wide survey of shallow wells in -watersheds
•where agriculture is the predominant land use (Table 3-3).
The data come from the U.S. Geological Survey's National
Water Quality Assessment (NAWQA) study of major river
basins with agricultural activities, representing a large portion
of the nation's land area. Agricultural land use is among the
major sources of certain ground water contaminants such as
nutrients and pesticides.
Table 3-3. ROE Indicators of Trends in the Extent and Condition of
Ground Water and Their Effects on Human Health and the Environment
National Indicators
Nitrate and Pesticides in Shallow Ground Water in Agricultural Watersheds
Section
3.3.2
3-27
rate and Pesticides in Shallow Ground Water in
Agricultural Watersheds
Nitrogen is a critical plant nutrient, and most nitrogen is
used and reused by plants within an ecosystem (Vitousek
et al., 2002), so in undisturbed ecosystems minimal "leak-
age" occurs into ground water, and concentrations are
very low. When nitrogen fertilizers are applied in amounts
greater than can be incorporated into crops or lost to the
atmosphere, however, nitrate concentrations in ground
•water can increase. Elevated nitrogen levels in ground water
also might result from disposal of animal waste or onsite
septic systems. Nitrate contamination in shallow ground
•water (less than 100 feet below land surface) raises potential
concerns for human health where untreated shallow ground
•water is used for domestic water supply. High nitrate con-
centrations in drinking water pose a risk for methemoglo-
binemia, a condition that interferes with oxygen transport in
the blood of infants (U.S. EPA, 2004).
More than a billion pounds of pesticides (measured as
pounds of active ingredient) are used in the U.S. each
year to control weeds, insects, and other organisms that
threaten or undermine human activities (Aspelin, 2003).
About 80 percent of the total is used for agricultural
purposes. Although pesticide use has resulted in increased
crop production and other benefits, pesticide contamina-
tion of ground water poses potential risks to human health
if contaminated ground water is used as a drinking water
source—especially if untreated.
This indicator reports on the occurrence of nitrate and
pesticides in shallow ground water in -watersheds where
agriculture is the primary land use, according to criteria
outlined in Gilliom et al. (2007). Ground water samples
•were collected by the U.S. Geological Survey's (USGS's)
National Water Quality Assessment (NAWQA) program
from 1992 to 2003 (pesticide sampling began in 1993).
NAWQA surveyed 51 major river basins and aquifer regions
across the contiguous United States during this period; the
Exhibit 3-15. Nitrate in shallow ground water
in agricultural watersheds of the contiguous
U.S., 1992-2003ab
100
60
40
20
34.5
7.7
23.0
13.5
21.4
Coverage: 1,423 shallow wells in
watersheds where agriculture is
the predominant land use. These
watersheds are within 34 major river
basins and aquifer regions studied
by the USGS NAWQA program.
"Totals may not add to 100% due to
rounding.
=EPA's drinking water standard for
nitrate is a Maximum Contaminant
Level (MCL) of 10mg/L
Data source: USGS, 2007a
agricultural -watersheds sampled -were -within 34 of these
study units. Although agriculture is more prevalent in some
parts of the country than in others, the -watersheds -were
chosen to reflect a broad range of hydrogeologic condi-
tions and agricultural activities. Ground -water samples -were
collected from existing household wells -where possible and
new observation wells other-wise, all targeted at the upper-
most aquifer and avoiding locations -where ground -water
condition could be biased by point sources (e.g., directly
EPA's 2008 Report on the Environment
3-27
-------
INDICATOI
Nitrate and Pesticides in Shallow Ground Water in
Agricultural Watersheds (continued)
downgradient from a septic system). Most of the wells sam-
pled ground water from less than 20 feet below the water
table, indicating as directly as possible the influence of land
use on shallow ground water quality. To the extent feasible,
the wells were intended to sample recently recharged water.
Data analyses were based on one sample per well. Related
indicators report concentrations of nutrients and pesticides
in streams that drain agricultural -watersheds (see the N and
P in Agricultural Streams indicator, p. 3-15, and the Pesti-
cides in Agricultural Streams indicator, p. 3-19).
The nitrate component of this indicator represents 1,423
wells. Results are compared with the federal drinking water
standard of 10 mg/L, which is EPA's Maximum Contami-
nant Level (MCL) to prevent methemoglobinemia (U.S.
EPA, 2006). MCLs are enforceable standards representing
the highest level of a contaminant that is allowed in finished
drinking water. MCLs take into account cost and best avail-
able treatment technology, but are set as close as possible to
the level of the contaminant below which there is no known
or expected risk to health, allowing for a margin of safety.
Data on 75 pesticides and eight pesticide degradation
products were collected from 1,412 of the wells in the
NAWQA study. These 83 chemicals account for approxi-
mately 78 percent of the total agricultural pesticide applica-
tion in the United States by weight during the study period
(Gilliom et al., 2007). Three types of U.S. EPA human
health-related standards and guidelines were used to evaluate
pesticide data: Maximum Contaminant Levels (MCLs) (as
described above), Cancer Risk Concentrations (CRCs), and
Lifetime Health Advisories (HA-Ls). In all three cases, the
standard and guideline levels are concentrations pertaining
to lifetime exposure through drinking water. The CRC is a
guideline for potential carcinogens associated with a speci-
fied cancer risk of 1 in 1,000,000, based on drinking water
exposure over a 70-year lifetime. The HA-L is an advisory
guideline for drinking water exposure over a 70-year life-
time, considering non-carcinogenic adverse health effects.
Specific standards and guidelines used for this indicator are
listed in Gilliom et al. (2007), and additional information
on these types of benchmarks, their derivation, and their
underlying assumptions is provided in Nowell and Resek
(1994). For this indicator, if a chemical had multiple bench-
marks, the MCL took precedence; if no MCL was available,
the lower of the CRC (at 1 in 1,000,000 cancer risk) and
HA-L values was selected. An exceedance was identified if
the concentration of a contaminant exceeded the relevant
standard or guideline (Gilliom et al., 2007).
What the Data Show
During the study period:
• Nitrate concentrations were 2 mg/L or above in 58 percent
of wells sampled in areas where agriculture is the primary
Exhibit 3-16. Pesticides in shallow ground
water in agricultural watersheds of the
contiguous U.S., 1993-2003ab
A. Compounds
detected
. Exceedances of
human health
benchmarks
100
60
I 40
20
39.4
31.3
19.8
9.5
98.9
1.1
Number of
compounds:
D 0
D 1or2
D 3 or 4
• 5 or more
Coverage: 1,412 shallow wells in watersheds where agriculture is the
predominant land use. These watersheds are within 34 major river
basins and aquifer regions studied by the USGS NAWQA program.
bSamples were analyzed for 75 pesticides and eight pesticide
degradation products.
=l\lo wells exceeded benchmarks for more than one compound.
Data source: Gilliom et al., 2007
land use (Exhibit 3-15). By comparison, background nitrate
levels in areas with little human influence are generally
expected to be below 1 mg/L (Nolan and Hitt, 2002).
• Nitrate concentrations in about 21 percent of the wells
exceeded the federal drinking water standard (10 mg/L).
• About 60 percent of wells in agricultural -watersheds had at
least one detectable pesticide compound, and 9.5 percent
had detectable levels of five or more pesticides (Exhibit
3-16). Roughly 1 percent of wells had pesticides present at
concentrations exceeding human health benchmarks.
Indicator Limitations
• These data only represent conditions in agricultural
•watersheds within 34 of the major river basins and aquifer
regions sampled by the NAWQA program from 1992
to 2003. Although sample wells were chosen randomly
•within each agricultural -watershed, the -watersheds and
aquifers themselves -were selected through a targeted sam-
ple design. The data also are highly aggregated and should
only be interpreted as an indication of national patterns.
3-28
EPA's 2008 Report on the Environment
-------
INDICATOI
Nitrate and Pesticides in Shallow Ground Water in
Agricultural Watersheds (continued)
• This indicator does not provide information about trends
over time, as the NAWQA program has completed only
one full sampling cycle to date. Completion of the next
round of sampling will allow trend analysis, using the
data presented here as a baseline.
• Drinking water standards or guidelines do not exist for 43
percent (36 of 83) of the pesticides and pesticide degrada-
tion products analyzed. Current standards and guidelines
also do not account for mixtures of pesticide chemi-
cals and seasonal pulses of high concentrations. Possible
pesticide effects on reproductive, nervous, and immune
systems, as well as on chemically sensitive individuals, are
not yet well understood.
• This indicator does not provide information on the
magnitude of pesticide concentrations, only whether
they exceed or fall below benchmarks. It also does not
describe the extent to which they exceed or fall below
other reference points (e.g., Maximum Contaminant
Level Goals [MCLGs] for drinking water).
Data Sources
Summary data for this indicator were provided by USGS's
NAWQA program. Nitrate data have not yet been pub-
lished and were provided directly by USGS (2007a);
however, concentration data from individual sample sites
are publicly available through NAWQA's online data
•warehouse (USGS, 2007b). Pesticide occurrence and
exceedances were determined from individual site results
in Appendix 6 of Gilliom et al. (2007) (http://water.usgs.
gov/nawqa/pnsp/pubs/circ!291/appendix6/).
References
Aspelin, A.L. 2003. Pesticide usage in the United States:
Trends during the 20th century. Raleigh, NC: Center for
Integrated Pest Management, North Carolina State Univer-
sity.
Gilliom, R.J., J.E. Barbash, C.G. Crawford, P.A. Hamilton,
J.D. Martin, N. Nakagaki, L.H. Nowell, J.C. Scott, P.E.
Stackelberg, G.P. Thelm, and D.M. Wolock. 2007. Pesti-
cides in the nation's streams and ground water, 1992-2001.
U.S. Geological Survey circular 1291. Revised February 15,
2007. (document); (supporting
technical information)
Nolan, B.T., and KJ. Hitt. 2002. Nutrients in shallow
ground waters beneath relatively undeveloped areas in the
conterminous United States. U.S. Geological Survey water
resources investigation report 02-4289.
Nowell, L.H., andE.A. Resek. 1994. National standards
and guidelines for pesticides in water, sediment, and
aquatic organisms: Application to water-quality assess-
ments. Rev. Environ. Contam. Toxicol. 140:1-164.
U.S. EPA (United States Environmental Protection Agency).
2006. Drinking water contaminants.
U.S. EPA. 2004. Consumer factsheet on nitrates/nitrites.
USGS (United States Geological Survey). 2007a. Data
provided to ERG (an EPA contractor) by Nancy Baker,
USGS. September 12, 2007.
USGS. 2007b. USGS National Water Quality Assessment
data -warehouse. Accessed 2007.
Vitousek, P., H. Mooney, L. Olander, and S. Allison. 2002.
Nitrogen and nature. Ambio 31:97-101.
*
3.3.3 Discussion
What This Indicator Says About Trends in
the Extent and Condition of Ground Water
and Their Effects on Human Health and the
Environment
The Nitrate and Pesticides in Ground Water indicator (p. 3-27)
describes the extent to which the condition of shallow ground
•water may be influenced by human stressors—in this case,
Howarth, FL, D.Anderson,J. Cloern, C. Elfring, C. Hopkinson, B. Lapointe,T.
Malone, N. Marcus, K. McGlathery, A. Sharpley, and D.Walker. 2000. Nutrient
pollution of coastal rivers, bays, and seas. Issues in ecology, number 7. Wash-
ington, DC: Ecological Society of America.
certain chemicals applied to land in agricultural areas. Col-
lectively, the agricultural -watersheds sampled across the nation
had average nitrate concentrations that were substantially higher
than the background levels one might expect in an undisturbed
•watershed. Nitrate concentrations exceeded EPA's MCL for
nitrate in one-fifth of the wells, though this does not necessar-
ily reflect the condition of the water people drink if it is tested
and treated. Nitrate concentrations were often high enough that
they could impact ecological systems upon being introduced
into surface -waters.10'11 Pesticide compounds were detected
Jackson, FL, S. Carpenter, C. Dahm, D. McKnight, R. Naiman, S. Postel, and
S. Running. 2001. Water in a changing world. Issues in ecology, number 9.
Washington, DC: Ecological Society of America.
EPA's 2008 Report on the Environment
3-29
-------
frequently (more than half of the shallow wells sampled). How-
ever, detected pesticide concentrations rarely exceeded human
health-based reference points in the samples collected for this
indicator.
Limitations, Gaps, and Challenges
One challenge in answering this question is that there are cur-
rently no national indicators of ground -water extent. Com-
prehensive national data do not exist, particularly in terms of
real-time -water level monitoring. Statistics on -water use and
withdrawal might be considered a surrogate for ground -water
extent, but because withdrawal is but one factor that affects
extent (other factors include recharge rate and flow patterns),
the relationship between withdrawal and extent differs from
one location to another. Thus, the issue of extent currently
represents an information gap.
There are also several limitations, gaps, and challenges in
addressing the issue of ground -water condition. One notable
limitation to the Nitrate and Pesticides in Ground Water indi-
cator (p. 3-27) is that it does not provide information about
trends over time. The indicator is also limited in its ability
to represent the condition of entire aquifers. Because ground
•water condition is vertically heterogeneous, results from one
depth do not necessarily represent other depths. This indicator
characterizes the uppermost layer of shallow aquifers, -which
are used by many private wells. It does not provide informa-
tion about the condition of deeper aquifers, -which are more
likely to be used for public -water supplies.
The Nitrate and Pesticides in Ground Water indicator provides
a representative national picture of shallow ground -water condi-
tion in agricultural -watersheds. At present, similar indicators do
not exist for ground -water in -watersheds -with non-agricultural
land uses. Non-agricultural -watersheds—particularly urban
areas—reflect a different set of stressors, and to some extent a
different set of chemicals (i.e., VOCs and hydrocarbons like
MTBE12). Because many ground -water stressors in urban areas
are localized events such as plumes resulting from chemical
spills or underground storage tank (UST) leaks, they may be
harder to characterize on a national level—a potential challenge
to gathering more information about ground -water condition.
Salt -water intrusion is another issue that tends to occur locally,
and for -which national-scale data are not available.
3-30
12 Delzer, G.C., andT. Ivahnenko. 2003. Occurrence and temporal variability
of methyl tert-butyl ether (MTBE) and other volatile organic compounds
in select sources of drinking water: Results of the focused survey. USGS
series: water-resources investigations report. Report no. 2002-4084. Reston.
VA: US. Geological Survey,
EPA's 2008 Report on the Environment
3.4 What Are the Trends
in the Extent and
Condition of Wetlands
and Their Effects on
Human Health and the
Environment?
3.4.1 Introduction
The United States has many types of wetlands, which include
marshes, swamps, bogs, and similar marine, estuarine, or
freshwater areas that are periodically saturated or covered by
•water. Wetlands are an integral part of the landscape because
they provide habitat for a diverse array of plants and animals,
act as buffers to flooding and erosion, and serve as key links in
the global water and biogeochemical cycles.
In terms of extent, wetlands currently cover 5.5 percent of
the surface area of the contiguous 48 states, with fresh-wa-
ter \vetlands accounting for nearly 95 percent of the current
•wetland acreage and marine and estuarine wetlands accounting
for the remaining 5 percent.13 Condition is somewhat harder
to measure, as it reflects a combination of physical, chemical,
and biological attributes. To be in healthy condition, however,
a \vetland should generally demonstrate good -water quality
and support native plant and animal communities, -without the
presence of invasive non-indigenous species. A healthy -wetland
should not show signs of stress related to substantial degradation
or cumulative effects of smaller degradations, and should be free
of modifications that restrict -water flow into, through, or out of
the -wetland, or that alter patterns of seasonality.
Wetlands can be classified by many different attributes. First,
they can be divided by degree of salinity—fresh-water, marine,
or estuarine. Wetlands also may be classified based on dominant
vegetation type. For example, swamps are dominated by trees and
shrubs, while marshes are characterized by non-woody, emergent
(vertically oriented) plants like grasses and sedges. Other charac-
teristics used to classify -wetlands include soil type, -water source,
and the length of time a given wetland is saturated.
The structure and function of any given wetland -will be gov-
erned by a combination of interrelated factors, including topog-
raphy, underlying geology (e.g., mineral composition), the
abundance and movement of-water (hydrology), and-weather
and climate. These factors ultimately determine which plant and
animal species -will thrive in a given -wetland.
All -wetlands share a few basic physical, chemical, and biological
attributes. By definition, all -wetlands are saturated or covered
13 Dahl,T.E. 2006. Status and trends of wetlands in the conterminous United
States 1998 to 2004. Washington, DC: U.S. Department of the Interior, Fish
and Wildlife Service,
-------
by water at least periodically, and wetland vegetation is adapted
to these conditions. Thus, wetlands are like sponges, with a
natural ability to store water. Wetlands also tend to have highly
developed root systems that anchor trees and other vegetation in
place. This web of roots not only holds the soil in place, but also
filters pollutants out of the water as it flows through.
Because of their physical, chemical, and biological properties,
•wetlands serve many important environmental functions. They
play an important role in improving natural water quality by
filtering pollutants. This function is particularly important to
human health because it may affect the condition of waters
used as a source of drinking water—a topic described in greater
detail in Section 3.6. Wetlands also act as a buffer to protect
the shoreline from erosion and storm damage. Because of their
sponge-like capacity to absorb water, wetlands slow the -water's
momentum and erosive potential and reduce flood heights.
During dry periods, the "sponge" releases water, which is criti-
cal in maintaining the base flow of many surface water systems.
Wetlands are also among the most biologically productive nat-
ural ecosystems in the world. Microbial activity in wetlands
enriches the water and soil with nutrients. As the interface
between terrestrial and aquatic ecological systems, wetlands
provide food and habitat for many plant and animal species,
including rare and endangered species. Because of these func-
tions, \vetlands support a number of human activities, includ-
ing commercial fishing, shellfishing, and other industries, as
•well as recreation, education, and aesthetic enjoyment.
In addition, wetlands play a role in global biogeochemi-
cal cycles, particularly those driven in part by the microbial
processes that occur in wetlands (e.g., the mineralization of
sulfur and nitrogen from decaying plants and the methylation
of mercury). Plant growth in wetlands provides a "sink" for
many chemicals including atmospheric carbon. If a wetland is
disturbed or degraded, these cycles can be altered and some of
the chemicals may be released.
The extent of wetlands can be affected by a variety of natural
stressors, such as erosion, land subsidence, changes in precipita-
tion patterns (e.g., droughts), sea level change, hurricanes, and
other types of storms. However, the vast majority of wetland
losses and gains over the last few centuries have occurred as a
result of human activity.14 For years, people have drained or
filled \vetlands for agriculture or urban and suburban develop-
ment, causing habitat loss or fragmentation as -well as a decline
in many of the other important functions outlined above, such
as improving -water quality. Conversely, other human activi-
ties may increase the extent of-wetlands—for example, creating
shallow ponds or re-establishing formerly drained or modified
•wetlands on farmlands.
Wetland extent may influence condition, as -wetland loss may
result in added stress to remaining -wetlands. For example, if
fewer -wetlands are available to filter pollutants from surface
•waters, those pollutants could become more concentrated in
remaining downgradient wetlands. Wetland loss and fragmenta-
tion also lead to decreases in habitat, landscape diversity, and the
connectivity among aquatic resources (i.e., fragmented wetlands
essentially become isolated wildlife refuges). Thus, stressors that
affect extent may ultimately affect condition as well.
Wetland condition also reflects the influence of stressors that
affect topography, hydrology, climate, water condition, and
biodiversity. For example, human modifications such as pipes
and channels can alter the topography, elevation, or hydrology of
•wetlands, while withdrawal of ground water or upstream surface
•waters can directly reduce inflow. Natural forces and human
activities (e.g., hurricanes, sea level change, and certain agri-
cultural and forestry practices) can also affect wetlands through
increased erosion or sedimentation. Pollutants in ground water
and fresh surface waters that flow into wetlands may be toxic to
plants and animals, and may also accumulate in wetland sedi-
ments. In addition, invasive species can alter the composition of
•wetland communities. Some of the most well-known invasives in
the U.S. are wetland species, including plants such as phragmites
and purple loosestrife and animals such as the nutria (a South
American rodent introduced to the Chesapeake and Gulf states).
Another key stressor to wetlands is conversion from one -wet-
land type to another. Although conversion can occur naturally
through plant succession (such as marshes turning into forested
•wetlands over time), human activities can cause more drastic
changes, such as clearing trees from a forested wetland, excavat-
ing a marsh to create an open water pond, or introducing certain
invasive species (e.g., the nutria, which converts tidal marsh to
open \vater by removing vegetation). Even if wetland extent is
not altered, conversion from one type to another has a major eco-
logical impact by altering habitat types and community structure.
3.4.2 ROE Indicators
An ROE indicator describes trends in -wetland extent, as -well as
specific activities that have contributed to recent -wetland losses
and gains (Table 3-4). Data -were collected as part of the U.S.
Fish and Wildlife Service's Wetlands Status and Trends survey,
a probabilistic national survey of-wetland acreage conducted
approximately every 10 years for the past half-century. There is
no ROE indicator for -wetland condition.
Table 3-4. ROE Indicators of Trends in the Extent and Condition of Wetlands
and Their Effects on Human Health and the Environment
National Indicators
Wetland Extent, Change, and Sources of Change
Section
3.4.2
3-32
14 Dahl,T.E. 2000. Status and trends of wetlands in the conterminous United
States, 1986 to 1997. Washington, DC: U.S. Department of the Interior, Fish
and Wildlife Service.
EPA's 2008 Report on the Environment
3-31
-------
INDICATOI
Wetland Extent, Change, and Sources of Change
Wetlands support a variety offish and wildlife species
and contribute to the aesthetic and environmental
quality of the U.S. Millions of Americans use freshwater
•wetlands annually for hunting, fishing, bird watching, and
other outdoor activities. Coastal wetlands provide valuable
nursery, feeding, breeding, staging, and resting areas for an
array offish, shellfish, mammals, and birds (Dahl, 2000).
In addition, wetlands serve as ground water recharge areas
and filter contaminants from surface runoff (Mitsch and
Gosselink, 1986). Destruction or alteration of wetlands,
therefore, can have wide-ranging biological, chemical, and
hydrological impacts.
Various lines of evidence suggest that when European
settlers first arrived, wetland acreage in the area that
•would become the contiguous 48 states was more than
twice \vhat it is today (Dahl, 1990). Since then, extensive
losses have occurred due to draining and filling. In addi-
tion to the sheer loss of wetland acreage, major ecological
impacts also have resulted from the conversion of one
•wetland type to another, such as clearing trees from a
forested wetland or excavating a shallow marsh to create
an open water pond. These types of conversions change
habitat types and community structure in -watersheds and
impact the animal communities that depend on them
(Dahl, 2000).
This indicator presents data from the U.S. Fish and
Wildlife Service's Wetlands Status and Trends survey.
Conducted approximately every 10 years, this survey pro-
vides an estimate of the extent of all wetlands in the con-
tiguous U.S., regardless of land ownership. The Status and
Trends survey uses a probabilistic design, based initially on
stratification of the 48 contiguous states by state boundaries
and 35 physiographic subdivisions. Within these subdivi-
sions are located 4,375 randomly selected 4-square-mile
(2,560-acre) sample plots. These plots are examined with
the use of aerial imagery. Although the imagery ranges in
scale and type, most are 1:40,000 scale, color infrared from
the National Aerial Photography Program. Field verifica-
tion is conducted to address questions of image interpreta-
tion, land use coding, and attribution of wetland gains or
losses; plot delineations are also completed. In the 1980s to
1990s analysis, 21 percent of the sample plots were field-
verified; in the most recent analysis, 32 percent were field-
verified (Dahl, 2000, 2006). The Fish and Wildlife Service
used the Cowardin et al. (1979) definition of wetlands,
•which is part of the draft national standard for wetland
mapping, monitoring, and data reporting as determined by
the Federal Geographic Data Committee.
This indicator shows trends in the total extent of-wet-
lands, as -well as the extent of several types of fresh-water
and intertidal -wetlands. In this analysis, fresh-water -wet-
lands include forested, shrub, emergent, and non-vegetated
Exhibit 3-17. Average annual change in wetland
acreage in the contiguous U.S., 1954-2004
100,000
— -100,000
-200,000
-300,000
-400,000
•£ -500,000
1954-1974 1974-1983 1986-1997
Reporting period
1998-2004
Data source: Dahl, 2006
•wetlands (e.g., shallow ponds). Intertidal-wetlands include
marine areas (e.g., tidal flats and sandbars) and estuarine
areas (vegetated or not) that are exposed and flooded by the
tides. Data on -wetland extent are described from several
Status and Trends analyses: 1950s-1970s, 1970s-1980s,
1980s-1990s, and 1998-2004 (Prayer et al., 1983; Dahl and
Johnson, 1991; Dahl, 2000, 2006). For the most recent
period, the indicator also describes sources of-wetland loss
or gain, -which the survey divided into five distinct land
use categories along -with an "other" category reflecting all
other land use types (Dahl, 2006).
What the Data Show
Total -wetland acreage declined over the last 50 years, but
the rate of loss appears to have slowed over time. From the
1950s to the 1970s, an average of 458,000 acres was lost
per year (Exhibit 3-17). By the 1986-1997 period, the loss
rate had declined to 58,600 acres per year; and in the most
recent study period, 1998-2004, -wetland area increased at a
rate of 32,000 acres per year (Exhibit 3-17).
Gains and losses have varied by -wetland type. Fresh-
water forested -wetlands, -which make up more than half
of all fresh-water -wetlands, lost acreage from the 1950s
to the 1990s but have shown gains over the last decade
(Exhibit 3-18, panel A). Fresh-water emergent -wetlands
have continued to lose acreage, although the rate of loss has
slowed recently (panel C). Among fresh-water categories,
forested -wetlands have sustained the greatest absolute losses
since the 1950s, about 9 million acres, -while emergent
•wetlands have shown the largest percentage loss (about
21 percent). Conversely, the extent of freshwater shrub
•wetlands increased until the 1990s but declined thereafter,
3-32
EPA's 2008 Report on the Environment
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INDICATOI
Wetland Extent, Change, and Sources of Change (continued)
1950s
1950s
suggesting that some of the gains and losses
in specific categories may reflect conver-
sion rather than outright wetland loss or
gam (Dahl, 2006; Exhibit 3-18, panel B).
Shallow freshwater ponds, mean-while,
have increased steadily throughout the last
50 years, with current acreage more than
twice what it was in the 1950s, although
still much less in absolute terms than the
other wetland types (panel D). These
•wetlands account for a large percentage of
the recent gains illustrated in Exhibit 3-17
(Dahl, 2006).
Since the 1950s, intertidal wetland acre-
age has decreased by about 700,000 acres,
or 12 percent (Exhibit 3-19, panel A).
This category includes marine, estuarine
vegetated, and estuarine non-vegetated
•wetlands. Both estuarine types lost acreage
overall, with estuarine vegetated wetlands,
the predominant type, losing over 400,000
acres (panel B). Long-term trends, however,
indicate that losses of intertidal wetlands
have slowed over time, with estuarine non-
vegetated \vetlands actually gaining acreage
over the last decade (panel C).
Between 1998 and 2004, urban devel-
opment, rural development, silviculture,
and conversion to deep-water (e.g., the
disappearance of coastal -wetlands or flooding to cre-
ate reservoirs) all contributed to losses in -wetland acre-
age (Exhibit 3-20). However, the net change in -wetland
acreage during this period -was positive, due largely to
•wetland creation and restoration on agricultural lands
(70,770 acres) and on lands classified as "other" (349,600
acres). This "other" category includes conservation lands,
areas in transition from one land use to another, and other
lands that do not fall into the major land use categories as
defined in Dahl (2006).
Indicator Limitations
• Different methods -were used in some of the early
schemes to classify -wetland types. As methods and spatial
resolution have improved over time, acreage data have
been adjusted, resulting in changes in the overall -wetland
base over time, thus reducing the accuracy of the trend.
• Ephemeral -waters and effectively drained palustrine
•wetlands observed in farm production are not recognized
as -wetland types by the Status and Trends survey and are
therefore not included in the indicator.
• Forested -wetlands are difficult to photointerpret and are
generally underestimated by the survey.
Exhibit 3-18. Extent of selected freshwater wetlands in the
contiguous U.S., 1950s-2000sa
A. Freshwater forested wetlands
B. Freshwater shrub wetlands
11.0
15.5 17.218.4 17.6
1970s 1980s 1990s 2000s
1950s
1970s 1980s 1990s 2000s
C. Freshwater emergent wetlands
26.4 26.3 26.1
1970s 1980s 1990s 2000s
D. Freshwater ponds
2.3
1950s
4.4 4.9 5.5 6.2
1970s 1980s 1990s 2000s
Decade
aBased on mid-decade surveys. No analysis was conducted for the 1960s.
Data source: Dahl, 2006
• The aerial imagery used for this survey generally does
not allow detection of small, isolated patches of-wetland
less than about an acre.
• Alaska and Hawaii are not included in the Status and
Trends survey.
• This survey does not include Pacific coast estuarine -wet-
lands such as those in San Francisco Bay, Puget Sound, or
Coos Bay, Oregon.
Data Sources
Data for this indicator -were obtained from Dahl (2006).
Historical trends are based on data originally presented in
earlier Fish and Wildlife Service reports (Dahl, 2000; Dahl
and Johnson, 1991; Prayer et al, 1983).
References
Cowardm, L.M., V. Carter, EC. Golet, and E.T LaRoe.
1979. Classification of-wetlands and deep-water habitats of
the United States. FWS/OBS-79/31. Washington, DC:
U.S. Department of the Interior, Fish and Wildlife Service.
Dahl, T.E. 2006. Status and trends of-wetlands in the con-
terminous United States 1998 to 2004. Washington, DC:
U.S. Department of the Interior, Fish and Wildlife Service.
EPA's 2008 Report on the Environment
3-33
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INDICATOR
Wetland Extent, Change, and Sources of Change (continued)
Exhibit 3-19. Extent of marine and estuarine
wetlands in the contiguous U.S., 1950s-2000sab
A. All intertidal wetlands (marine and estuarine)
1950s
1970s 1980s 1990s 2000s
Decade
B. Estuarine vegetated wetlands
4'85 4.62 4.60 4.57
1950s 1970s 1980s 1990s 2000s
Decade
C. Estuarine non-vegetated wetlands
0.68 0.59 0.59
0.60
1970s 1980s 1990s
Decade
2000s
aBased on mid-decade surveys. No analysis was conducted for
the 1960s.
bSurveys did not include Pacific coast estuarine wetlands.
=Panel A is the sum of panel B, panel C, and marine wetland acreage.
Data source: Dahl, 2006
Exhibit 3-20. Sources of wetland gain and loss
in the contiguous U.S., 1998-2004
'% 400,000
o
ro
~ 300,000
QJ
X
-S 200,000
_ro
S 100,000
_c
Dahl, T.E. 1990. Wetlands losses in the United States
1780s to 1980s. Washington, DC: U.S. Department of the
Interior, Fish and Wildlife Service.
Dahl, T.E., and C.E.Johnson. 1991. Status and trends of
•wetlands in the conterminous United States, mid-1970s
to mid-1980s. Washington, DC: U.S. Department of the
Interior, Fish and Wildlife Service.
Prayer, W.E., TJ. Monahan, D.C. Bowden, and F.A. Gray-
bill. 1983. Status and trends of wetlands and deep-water
habitats in the conterminous United States, 1950s to 1970s.
Ft. Collins, CO: Colorado State University.
Mitsch, W.J., andJ.G. Gosselmk. 1986. Wetlands. New
York, NY: Van Nostrand Reinhold Company Inc.
3-34
EPA's 2008 Report on the Environment
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3.4.3 Discussion
What This Indicator Says About Trends in
the Extent and Condition of Wetlands and
Their Effects on Human Health and the
Environment
Wetland extent in the contiguous 48 states is substantially lower
than it was prior to -widespread European settlement and it
generally continued to decline over the last 50 years (Wetlands
indicator, p. 3-32). The rate of loss of wetlands overall and for
most types of wetlands has slowed over time, however, and
since 1998 the overall extent of wetlands has actually increased.
Not all types of wetlands have experienced the same rate of
losses or overall percent losses. For example, freshwater shrub
•wetlands actually increased over the last 50 years—providing
evidence of wetland conversion, most likely from forested
•wetlands to shrub. The nation has also seen a steady increase
in acreage of freshwater ponds, which account for a substantial
portion of the recent gains in overall wetland acreage.
This indicator also confirms the role of many of the stressors
described in Section 3.4.1. Over the last decade, development,
forestry, and conversion to deep-water (e.g., marsh to open
•water) have led to losses in wetland extent, while agricul-
tural areas have experienced overall gains in wetland acreage.
The other source of new wetland acreage is from the "other"
land use category, which reflects the growing importance of
constructed and restored wetlands, including ponds associated
•with golf courses and residential development.
While this indicator does not directly quantify the condition
of the nation's wetlands, it suggests that the condition of many
•wetlands may be impacted. As discussed in Section 3.4.1, extent
can be a partial surrogate for condition because wetland loss can
increase the stress on those wetlands that remain, while decreas-
ing their connectivity. Thus, the overall decline in extent over
the last 50 years suggests the potential for substantial ecological
impacts such as habitat loss and increased flood impacts. Changes
in the extent of different types of wetlands also suggest changes in
condition. Shallow ponds, which constitute a large fraction of the
recent gains in wetland acreage, will not perform the same range
and type of environmental functions as the vegetated wetlands
that disappeared between the 1950s and the 1990s, some of which
continue to be lost. Similarly, evidence of wetland conver-
sion indicates that even if extent is no longer declining rapidly,
changes in wetland structure and function are still occurring. In
the past, studies have shown that wetlands that have been created
to mitigate wetland losses have not yet provided the same func-
tions and values of the wetlands that were lost.15'16
Limitations, Gaps, and Challenges
By relying on aerial imagery and statistical surveying tech-
niques, the Wetlands indicator (p. 3-32) provides a national
15 National Research Council. 2001. Compensating for wetland losses under the
Clean Water Act. Washington, DC: National Academies Press.
estimate using a logistically plausible number of samples.
However, a limitation to this survey is that it may omit or
undercount certain types of wetlands, including forested -wet-
lands—\vhich are difficult to photointerpret—and ephemeral
or -well-drained agricultural -wetlands, -which are not neces-
sarily obvious to the surveyor but are particularly threatened
by development. This indicator also does not include -wetland
parcels smaller than about 1 acre, -which become more critical
as larger -wetlands are fragmented into smaller pieces.
Wetland condition poses a larger challenge for assessment. While
the Wetlands indicator (p. 3-32) provides information that can
be used to infer potential -wetland condition, it does not explic-
itly measure condition—in part because condition is difficult to
quantify. Condition is made up of many different attributes, and
each -wetland has its own unique baseline condition and function,
•with a unique hydrologic setting and combination of plant and
animal species. Some studies have quantified regional changes
in specific stressors; however, national indicators would have to
bring together many regional datasets and cover many different
aspects of condition in order to be truly comprehensive. The lack
of such national-scale information is currently a gap in addressing
the question of wetland condition. Potential human health effects
associated with wetland extent and condition are also difficult to
quantify, and there are no ROE indicators on this topic.
Another information gap concerns the spatial patterns of
•wetland change, which are not documented in the existing
national data. Are most large wetlands being left intact? Are
human activities threatening to fragment larger wetlands into
smaller pieces that are less connected and more isolated, and
therefore less able to perform the desired ecological functions?
Data on patterns of wetland loss—e.g., fragmentation and
edge effects—would be a useful complement to the existing
data on overall losses and gains.
3.5 What Are the Trends
in the Extent and
Condition of Coastal
Waters and Their Effects
on Human Health
the Environment?
3.5.1 Introduction
Coastal \vaters are one of the nation's most important natural
resources, valued for their ecological richness as -well as for the
many human activities they support. As the interface between
16 MackJ.J., and M.Micacchion. 2006. An ecological assessment of Ohio miti-
gation banks:Vegetation, amphibians, hydrology, and soils. Ohio EPA Techni-
cal Report WET/2006-1. Columbus, OH: Ohio Environmental Protection
Agency.
EPA's 2008 Report on the Environment
3-35
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terrestrial environments and the open ocean, coastal waters
encompass many unique habitats, such as estuaries, coastal
•wetlands, seagrass meadows, coral reefs, mangrove and kelp
forests, and upwelling areas.17'18 Coastal waters support many
fish species for at least part of their life cycle, offering some
of the most productive fisheries habitats in the world. These
•waters also provide breeding habitat for 85 percent of U.S.
waterfowl and other migratory birds (largely in coastal -wet-
lands),19 and support many other organisms with high public
visibility (e.g., marine mammals, corals, and sea turtles) or
unique ecological significance (e.g., submerged aquatic vegeta-
tion). For humans, coastal -waters provide opportunities for
tourism and recreation, and they contribute to the economy
through transportation, fisheries, and mining and utilities.20
Lands adjacent to the coast are highly desirable places for
people to live, and represent the most densely developed areas
in the nation.21
Extent and condition are two key variables in assessing coastal
•waters and their ability to serve ecological and human needs.
The extent of coastal waters—i.e., the spatial area—is par-
ticularly important in terms of the extent of specific types of
coastal \vaters, such as coastal -wetlands or coral reefs. The con-
dition of coastal -waters reflects a group of interrelated physical,
chemical, biological, and ecological attributes. For example,
nutrient levels should be sufficient to support the food web but
not so high as to cause eutrophication, -while toxic chemi-
cal contaminants in -water and sediment may pose a threat to
aquatic organisms or accumulate in the food web. Of particu-
lar concern to human health are contaminants in consumable
fish and shellfish—a topic discussed separately in Section 3.8.
Other key aspects of condition include levels of pathogens and
organisms that produce biotoxins—-which may pose a risk to
human health through aquatic recreation or contaminated
fish and shellfish, and -which may impact the environment by
injuring native populations. Also important is the degree to
•which native plant and animal populations are healthy and
their habitats intact.
Many factors can affect the extent of coastal -waters. For
example, the extent of coastal -wetlands may be influenced by
natural events such as erosion or storms, or by human activi-
ties such as draining or filling -wetlands for development.
Natural processes can change the shape of a coastline, -with
•wave action eroding some areas while building up sediment
in others, and rivers depositing sediments at their mouth.
Human stressors can alter these patterns—for example,
through the construction of seawalls or barriers or through
the channeling of rivers, which can lead to subsidence in
coastal areas that would other-wise be naturally replenished
by sediments.
Changes in extent may in turn affect the condition of coastal
•waters. For example, beach erosion and coastal wetland loss
can also affect contaminant and sediment levels, nutrient
cycling, and the condition of spawning and feeding grounds
for fish, shellfish, and other coastal species. As described in
Section 3.4.1, the loss of some wetlands can also affect the
condition of the wetlands that remain.
Other stressors to the condition of coastal waters include nutri-
ents, pathogens, and chemical contaminants, which may pose
risks to ecological systems or to human health. Nutrients and
pathogens occur naturally, but their abundance can be increased
by human activities along the coast or in upstream -watersheds
that ultimately discharge to coastal -waters. Major sources
include urban and suburban storm -water, agricultural runoff,
and sewage discharge or overflows. Chemical contaminants
may come from these same sources, as -well as from industrial
activities that discharge treated -waste-waters and from atmo-
spheric deposition of airborne pollutants.
Several other stressors can affect the quality of habitat
and the status of native plant and animal populations. For
example, many species are sensitive to temperature and salin-
ity, -which can be influenced by changes in -weather patterns
or the condition of fresh-water inputs. Salinity is particu-
larly important in estuaries, -where species may depend on
a steady, reliable flow of fresh -water. Another factor affect-
ing the status of native communities is the presence and
abundance of non-indigenous species—particularly invasive
species that can kill or crowd out native populations, or oth-
er-wise alter coastal -watersheds. Populations offish, shellfish,
marine mammals, and other species used by humans may
also be affected by overharvesting.
In many cases, stressors that affect coastal condition are inter-
related. For example, excess nutrients can cause algal blooms
(and subsequent decay) that result in low dissolved oxygen and
reduced -water clarity—the chain of events known as eutro-
phication. Temperature and salinity can also influence algal
blooms. Some algae, such as "red tide," produce toxins that
pose risks to humans.
17 U.S. Environmental Protection Agency. 2004. National coastal condition
report II. EPA/620/R-03/002.
18 Although the Laurentian Great Lakes are included in EPA's Coastal Condi-
tion Report because they fall under the "Great Waters" designation, in the
ROE they are covered in the question on fresh surface waters, Section 3.2.
19 U.S. Environmental Protection Agency. 2004. National coastal condition
report II. EPA/620/R-03/002.
National Oceanic and Atmospheric Administration. 2005. Economic statistics
for NOAA.May 2005. Fourth edition. U.S. Department of Commerce.
National Oceanic and Atmospheric Administration. 2004. Population trends
along the coastal United States: 1980-2008. Coastal trends report series. Silver
Spring, MD: U.S. Department of Commerce, National Ocean Service.
3-36
EPA's 2008 Report on the Environment
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3.5.2 ROE Indicators
Five National Indicators and two Regional Indicators
characterize the extent and condition of coastal waters
(Table 3-5). National Indicators describe sediment qual-
ity, benthic community condition, contamination in fish
tissue, and several aspects of coastal water quality, as well
as trends in the extent of marine and estuarine wetlands.
The Regional Indicators characterize trends in the extent
of areas with low dissolved oxygen (i.e., hypoxia) and
the extent of submerged aquatic vegetation (SAV). These
Regional Indicators reflect conditions in three important
and unique coastal water bodies: the Gulf of Mexico, Long
Island Sound, and the Chesapeake Bay.
The National Indicator on wetland extent is based on data
gathered from aerial and ground surveys conducted as part
of the U.S. Fish and Wildlife Service's Wetlands Status
and Trends study, a long-term statistical sampling effort.
The other four National Indicators are derived from EPA's
second National Coastal Condition Report, which involved
probabilistic surveys designed to represent 100 percent of
estuarine acreage in the contiguous 48 states and Puerto
Rico. In addition to national totals, these four indicators
present data by EPA Region. The Regional Indicator on
trends in hypoxia reflects data from two long-term water
sampling programs, while the indicator on SAV is based on
aerial imagery.
Table 3-5. ROE Indicators of Trends in the Extent and Condition of
Coastal Waters and Their Effects on Human Health and the Environment
National Indicators
Wetland Extent, Change, and Sources of Change
Trophic State of Coastal Waters (N/R)
Coastal Sediment Quality (N/R)
Coastal Benthic Communities (N/R)
Coastal Fish Tissue Contaminants (N/R)
Section
3.4.2
3.5.2
3.5.2
3.5.2
3.8.2
Regional Indicators Section
Submerged Aquatic Vegetation in the Chesapeake Bay
Hypoxia in the Gulf of Mexico and Long Island Sound
3.5.2
3.5.2
Page
3-32
3-38
3-42
3-44
3-61
Page
3-46
3-48
N/R = National Indicator displayed at EPA Regional scale
EPA's 2008 Report on the Environment
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INDICATOI
Trophic State of Coastal Waters
While the presence of many water pollutants can lead
to decreases in coastal water quality, four interlinked
components related to trophic state are especially criti-
cal: nutrients (nitrogen and phosphorus), chlorophyll-a,
dissolved oxygen, and water clarity. "Trophic state"
generally refers to aspects of aquatic systems associated
•with the growth of algae, decreasing water transparency,
and low oxygen levels in the lower water column that
can harm fish and other aquatic life. Nitrogen is usually
the most important limiting nutrient in estuaries, driv-
ing large increases of microscopic phytoplankton called
"algal blooms" or increases of large aquatic bottom plants,
but phosphorus can become limiting in coastal systems
if nitrogen is abundant in a bioavailable form (U.S. EPA,
2003). Nitrogen and phosphorus can come from point
sources, such as wastewater treatment plants and indus-
trial effluents, and nonpoint sources, such as runoff from
farms, over-fertilized lawns, leaking septic systems, and
atmospheric deposition. Chlorophyll-a is a surrogate
measure of phytoplankton abundance in the water col-
umn. Chlorophyll-a levels are increased by nutrients and
decreased by filtering organisms (e.g., clams, mussels, or
oysters). High concentrations of chlorophyll-a indicate
overproduction of algae, which can lead to surface scums,
fish kills, and noxious odors (U.S. EPA, 2004). Low dis-
solved oxygen levels and decreased clarity caused by algal
blooms or the decay of organic matter from the -water-
shed are stressful to estuarine organisms. Reduced water
clarity (usually measured as the amount and type of light
penetrating water to a depth of 1 meter) can be caused
by algal blooms, sediment inputs from the -watershed, or
storm-related events that cause resuspension of sediments,
and can impair the normal growth of algae and other sub-
merged aquatic vegetation.
This indicator, developed as part of EPA's Coastal Condi-
tion Report, is based on an index constructed from proba-
bilistic survey data on five components: dissolved inorganic
nitrogen, dissolved inorganic phosphorus, chlorophyll-a,
daytime dissolved oxygen in bottom or near-bottom
•waters (where benthic life is most likely to be affected),
and \vater clarity (U.S. EPA, 2004). The survey, part of
EPA's National Coastal Assessment (NCA), -was designed
to provide a national picture of water quality by sampling
sites in estuarine -waters throughout the contiguous 48
states and Puerto Rico. Each site -was sampled once during
the 1997-2000 period, -within an index period from July to
September. The indicator reflects average condition during
this index period.
Key factors like sediment load, mixing processes, and eco-
system sensitivity naturally vary across biogeographic regions
and even among estuaries -within regions. Thus, reference
guidelines for nutrients, -water clarity, and chlorophyll-a -were
established based on variable expectations for conditions in
Exhibit 3-21. Coastal water quality index for the
contiguous U.S. and Puerto Rico, by EPA
Region, 1997-20003
Water quality:
High
Moderate
Low
Unsampled
71
20
1
Percent of estuarine area in each category:
Region 1
Region 2
Regions
Region 4
Region 6
Region 9
Region 10
All U.S.b
9
8
48
8
52
46
38
35
36
46
55
8
7
23
29
40
62
15
70 I
49
11
Coverage: Estuarine waters of the
contiguous 48 states and Puerto Rico
Does not include the hypoxic zone in
offshore Gulf Coast waters.
bU.S. figures reflect the total sampled
area. Unsampled areas were not
included in the calculation.
Data source: U.S. EPA, 2004,2005a
EPA Regions
different biogeographic regions. For example, due to
Pacific up-welling during the summer, higher nutrient and
chlorophyll-a concentrations are expected in West Coast
estuaries than in other estuaries. Water clarity reference
guidelines are lower for estuaries that support seagrass
than for naturally turbid estuaries. A single national
reference range of 2-5 milligrams per liter (mg/L) -was
used for dissolved oxygen, because concentrations below
2 mg/L are almost always harmful to many forms of
aquatic life and concentrations above 5 mg/L seldom
are (Diaz and Rosenberg, 1995; U.S. EPA, 2000). The
process of classifying individual sites varies by region and
is described in detail, along -with the regional reference
conditions, in U.S. EPA (2004).
The overall -water quality index is a compilation of the
five components. For each site, the index is rated high if
none of the five components received a score that -would
3-38
EPA's 2008 Report on the Environment
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INDICATOI
Trophic State of Coastal Waters (continued)
Exhibit 3-22. Nitrogen concentrations in coastal
waters of the contiguous U.S. and Puerto Rico,
by EPA Region, 1997-2000abc
Nitrogen concentration:
Low
Moderate
High
Unsampled
74
17
9
27
23
15
34
63
14
16
Percent of estuarine area in each category:
Region 1
Region 2
Regions
Region 4
Region 6
Region 9
Region 10
All U.S.d
12
84
13
12
100
82
13
EPA Regions
Coverage: Estuarine waters of the
contiguous 48 states and Puerto Rico.
bThis indicator measures dissolved
inorganic nitrogen (DIN), which is
the sum of nitrate, nitrite, and
ammonia.
=Totals may not add to 100% due to
rounding.
dU.S. figures reflect the total sampled area. Unsampled areas
were not included in the calculation.
Data source: U.S. EPA, 2004,2005a
be considered environmentally unfavorable (high nitro-
gen, phosphorus, or chlorophyll-a levels or low dissolved
oxygen or water clarity), and no more than one compo-
nent was rated moderate. Overall water quality is low if
more than two components received the most unfavorable
rating. All other sites receive a moderate index score. If
two or more components are missing, and the avail-
able components do not suggest a moderate or low index
rating, the site is classified as "unsampled." Data from
the individual sites were expanded from the probability
sample to provide unbiased estimates of the water quality
index and each of its components for each EPA Region.
Results were also aggregated and -weighted by estuarine
area for the entire nation.
Exhibit 3-23. Phosphorus concentrations in
coastal waters of the contiguous U.S. and
Puerto Rico, by EPA Region, 1997-2000abc
Phosphorus concentration:
Low
Moderate
High
Unsampled
Percent of estuarine area in each category:
Region 1
Region 2
Region3
Region 4
Region 6
Region 9
Region 10
All U.S.d
58
16
32 ||l
41
9
34
58
29 66
66
24 10
10
49
37 15
2
46
52
5 95
53
38
9
EPA Regions
Coverage: Estuarine waters of the
contiguous 48 states and Puerto Rico.
bThis indicator measures dissolved
inorganic phosphorus (DIP), which
equals orthophosphate.
=Totals may not add to 100% due to
rounding.
dU.S. figures reflect the total
sampled area. Unsampled areas were not included in the
calculation.
Data source: U.S. EPA, 2004, 2005a
What the Data Show
According to the index, 40 percent of estuarine surface
area nation-wide exhibited high -water quality over the
1997-2000 period, 11 percent had low -water quality, and
the remaining 49 percent -was rated moderate (Exhibit
3-21). Scores vary considerably among EPA Regions,
ranging from high -water quality in 71 percent of estuarine
area in Region 1 to less than 10 percent in Regions 2 and
3. Only one EPA Region had low -water quality in more
than 15 percent of its estuarine area (EPA Region 3, -with
36 percent). These percentages do not include the Great
Lakes or the hypoxic zone in offshore Gulf Coast -waters
(see the Hypoxia in Gulf of Mexico and Long Island
Sound indicator, p. 3-48).
EPA's 2008 Report on the Environment
3-39
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INDICATOR
Trophic State of Coastal Waters (continued)
Exhibit 3-24. Chlorophyll-a concentrations in
coastal waters of the contiguous U.S. and Puerto
Rico, by EPA Region, 1997-2000ab
Chlorophyll-a concentration:
Low
Moderate
High
Unsampled
Percent of estuarine area in each category:
Region 1
Region 2
Regions
Region 4
Region 6
Region 9
Region 10
All U.S.C
24
13
33
31 7
54
37
27
57
6
10
53
41
6
87
13
80
20
51
41
8
Coverage: Estuarine waters of the
contiguous 48 states and Puerto Rico.
"Totals may not add to 100% due to
rounding.
=U.S. figures reflect the total sampled
area. Unsampled areas were not
included in the calculation.
Data source: U.S. EPA, 2004,2005a
EPA Regions
Nitrogen concentrations were low in 82 percent of
estuarine area and high in 5 percent nation-wide, and were
low in a majority of the estuarine area in all but one EPA
Region (Exhibit 3-22). Regions 2 and 3 had the largest
percentage of area with high concentrations (15 percent
and 16 percent, respectively); several other EPA Regions
had no areas with high concentrations.
Phosphorus concentrations were low in 53 percent of
estuarine area and high in 9 percent nation-wide (Exhibit
3-23). Region 9 had the largest proportion of area exceed-
ing reference conditions (52 percent), -while Region 10 had
the least (none).
Chlorophyll-a concentrations -were low in 51 per-
cent and high in 8 percent of estuarine area nation-wide
(Exhibit 3-24). Region 3 had the largest percentage of area
exceeding reference conditions (27 percent); all other EPA
Regions had 10 percent or less in this category.
Exhibit 3-25. Dissolved oxygen levels in
coastal waters of the contiguous U.S. and
Puerto Rico, by EPA Region, 1997-2000ab
Region 1
Region 2
Regions
Region 4
Region 6
Region 9
Region 10
All U.S.C
High Moderate Low
(>5mg/L) (2-5mg/L) (<2mg/L) UnsamP|ed
'ercent of estuarine area in each category:
87 11
66 21 13
53 21 21 4
75 23
84 16
98
67 31
76 20 4
2
2
2
2
Coverage: Bottom- or near EPA Regions
bottom-water dissolved oxygen in a* . fjfb
estuarine waters of the contiguous
48 states and Puerto Rico. Does not
include the hypoxic zone in offshore
Gulf Coast waters.
bTotals may
rounding.
CU.S. figure
notinclud
Data sour
not add to 100% due to ®
\&$ L_
s reflect the total sampled area. Unsampled areas were
sd in the calculation.
ie: U.S. EPA, 2004, 2005a
Bottom-water dissolved oxygen -was above 5 mg/L
in over three-fourths of the nation's estuarine area and
below 2 mg/L in only 4 percent (Exhibit 3-25). While
effects vary -with temperature and salinity, as a general
rule, concentrations of dissolved oxygen above 5 mg/L are
considered supportive of marine life, concentrations below
5 mg/L are potentially harmful, and concentrations below
2 mg/L—a common threshold for hypoxia—are associated
•with a -wider range of harmful effects (e.g., some juvenile
fish and crustaceans that cannot leave the area may die).
Region 3 had the greatest proportion of estuarine area
•with low dissolved oxygen (21 percent), -while four EPA
Regions had no area below 2 mg/L.
3-40
EPA's 2008 Report on the Environment
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INDICATOI
Trophic State of Coastal Waters (continued)
Exhibit 3-26. Water clarity in coastal waters of
the contiguous U.S. and Puerto Rico, by EPA
Region, 1997-2000ab
Water clarity:
High
Moderate
Low
Unsampled
Percent of estuarine area in each category:
Region 1
Region 2
Region3
Region 4
Region 6
Region 9
Region 10
All U.S.C
95
82
10
38
14
43
66
12
19
47
22
31
65
11
24
44
18
38
62
13
25
Coverage: Estuarine waters of the
contiguous 48 states and Puerto Rico.
"Totals may not add to 100% due to
rounding.
=U.S. figures reflect the total sampled
area. Unsampled areas were not
included in the calculation.
Data source: U.S. EPA, 2004,2005a
EPA Regions
Water clarity exceeded reference conditions (i.e., higher
clarity) in 62 percent of the nation's estuarine area, while
low water clarity was observed in 25 percent of estuarine
area (Exhibit 3-26). Region 3 had the largest proportion of
area with low clarity (43 percent), while Region 1 had the
smallest (none).
Indicator Limitations
• The coastal areas of Hawaii and a portion of Alaska
have been sampled, but the data had not yet been
assessed at the time this indicator was compiled. Data
are also not available for the U.S. Virgin Islands and the
Pacific territories.
• Trend data are not yet available for this indicator. Because
of differences in methodology, the data presented here
are not comparable with data that appeared in EPA's first
National Coastal Condition Report. The data presented
here will serve as a baseline for future surveys.
• The NCA surveys measure dissolved oxygen conditions
only in estuarine waters and do not include observa-
tions of dissolved oxygen concentrations in offshore
coastal shelf \vaters, such as the hypoxic zone in Gulf
of Mexico shelf \vaters.
• At each sample location, the components of this indica-
tor may have a high level of temporal variability. This
survey is intended to characterize the typical distribution
of-water quality conditions in coastal -waters during an
index period from July through September. It does not
consistently identify the "-worst-case" condition for sites
experiencing occasional or infrequent hypoxia, nutrient
enrichment, or decreased -water clarity at other times of
the year.
Data Sources
This indicator is based on an analysis published in EPA's
second National Coastal Condition Report (U.S. EPA,
2004). Summary data by EPA Region have not been pub-
lished, but -were provided by EPA's NCA program (U.S.
EPA, 2005a). Underlying sampling data are housed in
EPA's NCA database (U.S. EPA, 2005b) (http://www.epa.
gov/emap/nca/html/data/index.html).
References
Diaz, R.J., and R. Rosenberg. 1995. Marine benthic
hypoxia: A review of its ecological effects and the behav-
ioral responses of benthic macrofauna. Oceanogr. Mar.
Biol. Ann. Rev. 33:245-303.
U.S. EPA (United States Environmental Protection
Agency). 2005a. Data provided to ERG (an EPA contractor)
by Kevin Summers, EPA. September 2005.
U.S. EPA. 2005b. EMAP national coastal database.
Accessed 2005.
U.S. EPA. 2004. National coastal condition report II.
EPA/620/R-03/002.
U.S. EPA. 2003. Mid-Atlantic integrated assessment,
MAIA—estuaries 1997-98, summary report.
EPA/620/R-02/003.
U.S. EPA. 2000. Ambient aquatic life -water quality criteria
for dissolved oxygen (salt-water): Cape Cod to Cape Hat-
teras. EPA/822/R-00/12.
EPA's 2008 Report on the Environment
3-41
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INDICATOI
Coastal Sediment Quality
Contaminated sediments can pose an immediate threat to
benthic organisms and an eventual threat to entire estua-
rine ecosystems. Sediments can be resuspended by anthro-
pogenic activities, storms, or other natural events; as a result,
organisms in the water column can be exposed to contami-
nants, which may accumulate through the food web and
eventually pose health risks to humans (U.S. EPA, 2004a).
There are several ways to measure sediment quality.
Sediments can be assessed in terms of their toxicity to
specific organisms in bioassays, or in terms of the levels of
contaminants that are present. Sediment quality also can be
inferred by assessing the condition of benthic communities,
•which largely reflect the quality of the sediments in which
they live (although other stressors may be reflected as well).
To generate a more complete picture of sediment quality,
scientists frequently use several of these measures together.
This indicator presents data on sediment toxicity and
contaminant levels. The data are from probabilistic surveys
conducted as part of EPA's National Coastal Assessment
(NCA) and presented in EPA's second National Coastal
Condition Report (U.S. EPA, 2004b). The survey was
designed to provide a national picture of sediment quality
by sampling sites in estuarine waters throughout the contig-
uous 48 states and Puerto Rico. Each site was sampled once
during the 1997-2000 period, within an index period from
July to September. The indicator reflects average condi-
tion in each EPA Region during this index period. Results
•were also aggregated and -weighted by estuarine area for the
entire nation.
Sediment toxicity is typically determined using bioassays
that expose test organisms to sediments and evaluate their
effects on the organisms' survival. For this indicator, toxic-
ity \vas determined using a 10-day static test on the benthic
amphipod Ampelisca abdita, which is commonly used as a
screening tool to identify sediments that pose sufficient
concern to -warrant further study. Sediments -were classified
as "potentially toxic" if the bioassays resulted in greater
than 20 percent mortality (a reference condition), or "not
likely toxic" if the bioassays resulted in 20 percent mortal-
ity or less (U.S. EPA, 2004c).
Contaminant concentrations do not directly reflect
toxicity because toxicity also depends on contaminants'
bioavailability, -which is controlled by pH, particle size and
type, organic content, and other factors (e.g., mercury vs.
methylmercury). Contaminant concentrations are a use-
ful screening tool for toxicity, however, -when compared
•with concentrations known to cause particular effects on
benthic life. For this indicator, sediment samples -were
homogenized and analyzed for nearly 100 contaminants,
including 25 polycyclic aromatic hydrocarbons (PAHs),
22 polychlorinated biphenyls (PCBs), 25 pesticides, and 15
metals, using standard wet chemistry and mass spectros-
copy. The observed concentrations -were then compared
•with "effects range median" (ERM) values established
Exhibit
of the cc
Region,
3-27. Sediment toxicity in coastal waters
>ntiguous U.S. and Puerto Rico, by EPA
1 997-2000 ab
Sediment toxicity:
Not likely toxic0
Potentially toxicd
Unsampled
Percent of estuarine area in each category:
Region 1
Region 2
Regions
Region 4
Region 6
Region 9
Region 10
All U.S.6
89.0
73.0
92.3
5.6
13.0 13.9
4.7
87.2
0.2 12.6
38.7
1 1.0 60.3
99.8
79.9
20.1
94.0
Coverage: Estuarine waters <
contiguous 48 states and Pu
Rico.
"Totals may not add to 100%
rounding.
cNot likely toxic: Mortality of
species = 20% or lower
Potentially toxic: Mortality o
species > 20%
eU.S. figures reflect the total s
not included in the calculatio
Data source: U.S. EPA, 2004
5.4
3.0
0.2
6.0
jfthe EPA Regions
erto
ftest
ampled area. Unsan
n.
b, 2005a
\f
ipled areas were
through an extensive review of toxicity tests involving
benthic organisms, mostly Ampelisca (Long et al., 1995).
ERM values were available for 28 contaminants. For each
contaminant, the ERM represents the concentration at
•which there is a 50 percent likelihood of adverse effects to
an organism, based on experimental data. For this indi-
cator, a site \vas rated "potentially toxic" if one or more
contaminants exceeded an ERM value. In practice, about
25 percent of samples that exceed one ERM also cause
more than 20 percent mortality in the Ampelisca bioassay
(Long, 2000).
Benthic community condition also can be a useful indi-
cation of sediment quality, particularly in terms of chronic
or community effects that would not be captured in an
acute exposure bioassay. The NCA evaluated estuarine
3-42
EPA's 2008 Report on the Environment
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INDICATOI
Coastal Sediment Quality (continued)
sites for several aspects of benthic community condition,
and these results are presented as a separate ROE indicator
(Coastal Benthic Communities, p. 3-44).
What the Data Show
Nationwide, 6 percent of coastal sediments were rated
"potentially toxic" based on the Ampelisca toxicity screen-
ing assay, although there was considerable variability from
one EPA Region to the next (Exhibit 3-27). In Region 9,
nearly 100 percent of estuarine area exhibited low sedi-
ment toxicity, while in some other EPA Regions, as much
as 20 percent of estuarine sediments were "potentially
toxic." Data for Region 6 are inconclusive because more
than half of the Region's estuarine area was not sampled.
Nationally, contaminants were present at "potentially
toxic" levels in 7 percent of estuarine sediments for which
contamination data were available (Exhibit 3-28). There was
considerable variability in sediment contamination from one
EPA Region to the next, with Region 4 showing the largest
proportion of estuarine area with sediments not likely to be
toxic (99.9 percent) and Region 2 showing the largest pro-
portion with "potentially toxic" sediments (24.4 percent).
Although the two figures suggest that a similar percent-
age of the nation's estuarine sediments are "potentially
toxic," the original data source reports very little correla-
tion between sites that caused more than 20 percent mor-
tality in the Ampelisca bioassay and sites where one or more
contaminants exceeded the ERM (U.S. EPA, 2004b). It
is not unusual to find a lack of correlation—particularly
in cases where sediment contaminants are neither highly
concentrated nor completely absent—in part because some
toxic chemicals may not be bioavailable, some may not be
lethal, and not all potentially toxic chemicals are ana-
lyzed (see O'Connor et al., 1998, and O'Connor and Paul,
2000). These results underscore the utility of a combined
approach to screen for potentially toxic sediments.
Indicator Limitations
• The coastal areas of Hawaii and a portion of Alaska have
been sampled, but the data had not yet been assessed at the
time this indicator was compiled. Data are also not avail-
able for the U.S. Virgin Islands and the Pacific territories.
• Trend data are not yet available for this indicator. Because
of differences in methodology, the data presented here
are not comparable with data that appeared in EPA's first
National Coastal Condition Report. The data presented
here will serve as a baseline for future surveys.
• Sample collection is limited to an index period from July
to September. It is not likely that contaminant levels vary
from season to season, however.
• The Ampelisca bioassay is a single-organism screening
tool, and the ERMs are general screening guidelines
based largely on toxicity data from Ampelisca. Thus,
Exhibit 3-28. Sediment contamination in
coastal waters of the contiguous U.S. and
Puerto Rico, by EPA Region, 1997-20003
Sediment contamination:
Not likely toxicb
Potentially toxic0
Unsampled
Percent of estuarine area in each category:
Region 1
Region 2
Regions
Region 4
Region 6
Region 9
Region 10
All U.S.d
90.0
4.6
62.0
24.4
13.6
88.2
9.4
5.4
2.4
99.9
0.1
81.7
18.3
92.8
93.0
1.9
7.0
"Coverage: Estuarine waters of the ^_ EPA Regions
contiguous 48 states and Puerto
Rico.
bNot likely toxic: No contaminants
above effects range median (ERM)
Potentially toxic: One or more
contaminants above effects range
median (ERM)
dU.S. figures reflect the total sampled area. Unsampled areas were
not included in the calculation.
Data source: U.S. EPA, 2004b, 2005a
these measures do not necessarily reflect the extent to
•which sediments may be toxic to the full range of biota
(including microbes and plants) that inhabit a particular
sampling location.
The Ampelisca bioassay tests only for short-term, not
long-term, exposure. Both screening tests characterize
sediments in terms of their effects on benthic organism
mortality. This indicator does not capture other effects
of sediment contaminants on benthic organisms, such as
disease, stress, and reproductive effects.
This indicator cannot be compared quantitatively with
indicators that use other types of contaminant guide-
lines. For example, the Pesticides in Agricultural Streams
indicator (p. 3-27) uses thresholds intended to be protec-
tive of aquatic life with a margin of safety, instead of
EPA's 2008 Report on the Environment
3-43
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INDICATOR
Coastal Sediment Quality (continued)
thresholds shown to cause biological effects (e.g., ERMs).
The ERM approach also is not directly comparable with
other sediment contaminant approaches, such as EPA's
equilibrium partitioning (EqP) benchmarks.
Data Sources
This indicator is based on an analysis published in EPA's sec-
ond National Coastal Condition Report (U.S. EPA, 2004b).
Summary data by EPA Region have not been published,
but were provided by EPA's NCA program (U.S. EPA,
2005a). Underlying sampling data are housed in EPA's NCA
database (U.S. EPA, 2005b) (http://www.epa.gov/emap/
nca/html/data/index.html).
References
Long, E.R. 2000. Degraded sediment quality in U.S.
estuaries: A review of magnitude and ecological applica-
tions. Ecol. Appl. 10(2):338-349.
Long, E.R, D.D. MacDonald, L. Smith, and ED. Calder.
1995. Incidence of adverse biological effects within ranges of
chemical concentrations in marine and estuarine sediments.
Environ. Manage. 19:81-97.
O'Connor, T.P., K.D. Daskalakis, J.L. Hyland, J.F. Paul,
andJ.K. Summers. 1998. Comparisons of sediment toxicity
•with predictions based on chemical guidelines. Environ.
Toxicol. Chem. 17(3):468-471.
O'Connor, T.P., and J.F. Paul. 2000. Misfit between
sediment toxicity and chemistry. Mar. Pollut. Bull.
40(l):59-64.
U.S. EPA (United States Environmental Protection Agency).
2005a. Data provided to ERG (an EPA contractor) by Kevin
Summers, EPA. September 2005.
U.S. EPA. 2005b. EMAP national coastal database.
Accessed 2005.
U.S. EPA. 2004a. Contaminated sediment in water.
U.S. EPA. 2004b. National coastal condition report II.
EPA/620/R-03/002.
U.S. EPA. 2004c. The incidence and severity of sediment
contamination in surface waters of the United States—
national sediment quality survey. Second edition.
INDICATOR
/oastal Benthic Communities
Benthic communities are largely composed of macro-
invertebrates, such as annelids, mollusks, and crusta-
ceans. These organisms inhabit the bottom substrates of
estuaries and play a vital role in maintaining sediment and
•water quality. They also are an important food source for
bottom-feeding fish, invertebrates, and birds. Communi-
ties of benthic organisms are important indicators of envi-
ronmental stress because they are particularly sensitive to
pollutant exposure (Holland et al., 1987). This sensitivity
arises from the close relationship between benthic organ-
isms and sediments—which can accumulate environmental
contaminants over time—and the fact that these organisms
are relatively immobile, which means they receive pro-
longed exposure to any contaminants in their immediate
habitat (Sanders et al., 1980; Nixon et al., 1986).
This indicator is based on a multi-metric benthic commu-
nities index that reflects overall species diversity in estuarine
areas throughout the contiguous United States (adjusted for
salinity, if necessary) and, for some regions, the presence
of pollution-tolerant and pollution-sensitive species (e.g.,
Weisberg et al., 1997; Engle and Summers, 1999; U.S. EPA,
2004). The benthic community condition at each sample
site is given a high score if the index exceeds a particular
threshold (e.g., has high diversity or populations of many
pollution-sensitive species), a low score if it falls below the
threshold conditions, and a moderate score if it falls within
the threshold range. The exact structure of the index and
the threshold values vary from one biogeographic region to
another, but comparisons between predicted and observed
scores based on expert judgment are used to ensure that the
classifications of sites from one region to another are consis-
tent (U.S. EPA, 2004). Data were collected using probability
samples, so the results from the sampling sites provide unbi-
ased estimates of the distribution of index scores in estuaries
throughout each region.
The data for this indicator are from probabilistic surveys
conducted as part of EPA's National Coastal Assessment
(NCA) and presented in EPA's second National Coastal
Condition Report (U.S. EPA, 2004). The survey was
designed to provide a national picture of coastal benthic
3-44
EPA's 2008 Report on the Environment
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INDICATOI
Coastal Benthic Communities (continued)
Exhibit
index fc
by EPA
Region 1
Reg ion 2
Regions
Reg ion 4
Reg ion 6
Reg ion 9
Region 10
All U.S.b
Coverage:
contiguou
Puerto Ric
bU.S. figure
sampled a
were not ir
Data sour
2005a
3-29. Coastal benthic communities
rthe contiguous U.S. and Puerto Rico,
Region, 1 997-2000 a
Benthic community condition:
High Moderate Low Unsamplec
Percent of estuarine area in each category:
77 18 5
59 17 24
72 27
63 17 17 :
51 27 11 11
1
78 15 7
91 5
70 13 17
t
Estuarine waters of the EPA Regions
; 48 states and
0
s reflect the total
rea. Unsampled areas
icluded in the calculation. tajjj)
-,e: U.S. EPA, 2004, , (jfcy 1
r
community condition by sampling sites in estuarine waters
throughout the contiguous 48 states and Puerto Rico. Each
site was sampled once during the 1997-2000 period, within
an index period from July to September. The indicator
reflects average condition in each EPA Region during this
index period. Results were also aggregated and -weighted
by estuarine area for the entire nation.
What the Data Show
Nationally, 70 percent of the sampled estuarine area had a
high benthic communities index score, with 13 percent in
the moderate range and 17 percent scoring low (Exhibit
3-29). Condition varied somewhat by EPA Region, with
high index scores ranging from 51 percent of the estuarine
area in Region 6 to 91 percent in Region 10. Region 3
had the largest proportion of estuarine area rated low (27
percent), while Region 10 had the lowest (4 percent). In
the figure, the portion of the estuarine area not represented
by the sample is noted for each Region.
The National Coastal Condition Report found that
many of the sites with low benthic community condition
also showed impaired water quality or sediment condi-
tion—which is not surprising given the extent to which
these stressors and effects are related. Of the 17 percent of
national estuarine area rated low on the benthic commu-
nities index, 38 percent also exhibited degraded sediment
quality, 9 percent exhibited degraded water quality (U.S.
EPA, 2004), and 33 percent exhibited degraded quality of
both sediment and water.
Indicator Limitations
• The coastal areas of Hawaii and a portion of Alaska have
been sampled, but the data had not yet been assessed at the
time this indicator was compiled. Data are also not avail-
able for the U.S. Virgin Islands and the Pacific territories.
• Trend data are not yet available for this indicator. Because
of differences in methodology, the data presented here
are not comparable with data that appeared in EPA's first
National Coastal Condition Report. The data presented
here will serve as a baseline for future surveys.
• Benthic indices for the Northeast, West, and Puerto
Rico do not yet include measures of pollution-tolerant or
pollution-sensitive species. Although species diversity has
the largest impact on index scores in the other regions,
index values could change in the future as these compo-
nents are added to the index values for these regions.
• Sample collection is limited to an index period from July
to September. Further, because benthic communities can
be strongly influenced by episodic events, trawling, or
climate perturbations, this indicator may not reflect the
full range of conditions that occur at each sampling loca-
tion throughout these months.
Data Sources
This indicator is based on an analysis published in EPA's
second National Coastal Condition Report (U.S. EPA,
2004). Summary data by EPA Region have not been pub-
lished, but were provided by EPA's NCA program (U.S.
EPA, 2005a). Underlying sampling data are housed in
EPA's NCA database (U.S. EPA, 2005b) (http://www.epa.
gov/emap/nca/html/data/index.html).
References
Engle, V.D., andJ.K. Summers. 1999. Refinement,
validation, and application of a benthic condition
index for northern Gulf of Mexico estuaries. Estuaries
22(3A):624-635.
Holland, A.F., A. Shaughnessy, andM.H. Heigel. 1987.
Long-term variation in mesohaline Chesapeake Bay ben-
thos: Spatial and temporal patterns. Estuaries 10:227-245.
Nixon, S.W., C.D. Hunt, andB.L. Nowicki. 1986. The
retention of nutrients (C, N, P), heavy metals (Mn, Cd,
EPA's 2008 Report on the Environment
3-45
-------
INDICATOR
Coastal Benthic Communities (continued)
Pb, Cu), and petroleum hydrocarbons by Narragansett
Bay. In: Lasserre, P., andJ.M. Martin, eds. Biogeochemi-
cal processes at the land-sea boundary. New York, NY:
Elsevier. pp. 99-122.
Sanders, H.L., J.F. Grassle, G.R. Hampson, L.S. Morse,
S. Gerner-Price, and C.C.Jones. 1980. Anatomy of an oil
spill: Long-term effects from the grounding of the barge
Florida off West Falmouth, Massachusetts. J. Mar. Res.
38:265-380.
U.S. EPA (United States Environmental Protection Agency).
2005a. Data provided to ERG (an EPA contractor) by Kevin
Summers, EPA. September 2005.
U.S. EPA. 2005b. EMAP national coastal database.
Accessed 2005.
U.S. EPA. 2004. National coastal condition report II.
EPA/620/R-03/002.
Weisberg, S.B., J.A. Ranasmghe, D.D. Dauer, L.C.
Schnaffer, RJ. Diaz, andJ.B. Frithsen. 1997. An estuarine
benthic index of biotic integrity (B-IBI) for Chesapeake
Bay. Estuaries 20(1):149-158.
INDICATOR
imerged Aquatic Vegetation in the Chesapeake Bay
Rooted aquatic plants, also called submerged aquatic
vegetation (SAV), represent an important component of
many coastal ecosystems. SAV supports the health of these
ecosystems by generating food and habitat for waterfowl,
fish, shellfish, and invertebrates; adding oxygen to the
•water column during photosynthesis; filtering and trapping
sediment that other-wise would bury benthic organisms
and cloud the water column; inhibiting wave action that
erodes shorelines; and absorbing nutrients, such as nitrogen
and phosphorus, that other-wise could fuel the growth of
unwanted planktonic algae.
One area -where SAV plays an important role is the
Chesapeake Bay, -where SAV has historically contributed
to high primary and secondary productivity (Kemp et al.,
1984). In the early 1960s, researchers began to note the loss
of SAV from shallow -waters of the Chesapeake Bay, -which
has since become a -widespread, -well-documented problem
(Batiuk et al., 2000). Review of aerial photographs taken
from a number of sites taken between the mid-1930s and
the mid-1960s suggests that SAV acreage is currently less
than half of-what it -was during the 1930s-1960s period
(Moore et al., 2004).
Trends in the distribution and abundance of SAV over
time are useful in understanding trends in -water quality
(Moore et al., 2004). Although other factors such as cli-
matic events and herbicide toxicity may have contributed
to the decline of SAV in the Bay, the primary causes are
eutrophication and associated reductions in light availabil-
ity (Batiuk et al., 2000). Like all plants, SAV needs sun-
light to grow and survive. Two key stressors that impact
the growth of SAV are suspended sediments and excess
nutrient pollution. Suspended sediments—loose particles
of clay and silt that are suspended in the -water—make the
Exhibit 3-30. Extent of submerged aquatic
vegetation (SAV) in the Chesapeake Bay,
1978-20063
100
60
40
^ 20
Mapped acreage
Estimated additional acreage'
78
'82
'90 '92 '94 '96
Year
'00 '02 '04 '06
aThere were no Bay-wide surveys
from 1979 to 1983, or in 1988.
bFor years with incomplete
photographic coverage, SAV
acreage in the non-surveyed areas
was estimated based on prior
years'surveys.
Data source: Chesapeake Bay Program, 2007
•water dingy and block sunlight from reaching the plants.
Similarly, excess nutrients in the -water fuel the growth of
planktonic algae, -which also block sunlight.
This indicator presents the distribution of SAV in the
Chesapeake Bay and its tributaries from 1978 to 2006, as
mapped from black and -white aerial photographs. The sur-
veys follow fixed flight routes to comprehensively survey
all shallow -water areas of the Bay and its tidal tributaries.
Non-tidal areas are omitted from the survey. SAV beds
3-46
EPA's 2008 Report on the Environment
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INDICATOR
Submerged Aquatic Vegetation in the Chesapeake Bay (continued)
less than 1 square meter in area are not included due to
the limits of the photography and interpretation. Annual
monitoring began in 1978; however, no surveys -were con-
ducted from 1979 to 1983 or in 1988. In years when the
entire area could not be surveyed due to flight restrictions
or -weather events, acreages in the non-surveyed areas -were
estimated based on prior years' surveys.
What the Data Show
The extent of SAV in the Chesapeake Bay increased from
41,000 acres in 1978 to a peak of 90,000 acres in 2002,
before declining to 59,000 acres in 2006 (Exhibit 3-30).
The extent of SAV reached a minimum of 38,000 acres in
1984. Year-to-year changes reflect a variety of phenom-
ena. For example, the notable decline in SAV distribu-
tion between 2002 and 2003 appears to be the result of
substantial reductions in widgeongrass populations in the
lower and mid-bay regions. In addition to the large declines
in widgeongrass, major declines in fresh-water SAV spe-
cies occurred in the upper portion of the Potomac River
and the Susquehanna region. While populations of SAV
appeared to be present in these segments very early in the
growing season, persistent turbidity resulting from rain
occurring throughout the spring and summer may have
contributed to a very early decline, -well before Hurricane
Isabel affected the Chesapeake Bay (Orth et al, 2004). The
extent of SAV gradually increased again through 2004 and
2005, then declined from 2005 to 2006. Factors causing
this latest decline are thought to include above-average
•water temperatures in the fall of 2005, a dry spring in 2006,
and an early summer rain event in 2006 (EcoCheck, 2007).
Indicator Limitations
• There -were no surveys in the years 1979-1983 or in 1988.
• The indicator includes some estimated data for years -with
incomplete photographic coverage. Spatial gaps in 1999
occurred due to the inability to reliably photograph SAV
folio-wing hurricane disturbance. Spatial gaps in 2001
occurred due to flight restrictions near Washington D.C.
after the September 11th terrorist attacks. Other gaps
occurred in 2003 due to adverse -weather in the spring,
summer, and fall (Hurricane Isabel). Acreage in the
non-surveyed areas -was estimated based on prior years'
surveys. In all cases, the estimated area accounted for less
than 10 percent of the total acreage of SAV.
• Photointerpretation methods changed over the course of
this study. However, data have been adjusted to account
for any methodological inconsistencies.
• Extent is just one of the variables that can be used to
measure the condition of SAV communities. Other use-
ful attributes that have been studied include vegetation
health, density, and species diversity.
Data Sources
Data were obtained from the Chesapeake Bay Program,
•which has published a version of this indicator (Chesapeake
Bay Program, 2007) along with a link to download the
annual summary data presented in Exhibit 3-30 (http://
www.chesapeakebay.net/pubs/statustrends/88-data-2002.
xls). These acreage statistics are based on annual SAV
distribution maps, which are available from the Virginia
Institute of Marine Science (VIMS, 2007) (http://www.
vims.edu/bio/sav/index.html).
References
Batiuk, R., P. Bergstrom, M. Kemp, E. Koch, L. Mur-
ray, C. Stevenson, R. Bartleson, V Carter, N. Rybicki, J.
Landwehr, C. Gallegos, L. Karrh, M. Naylor, D. Wil-
cox, K. Moore, S. Ailstock, andM. Teichberg. 2000.
Chesapeake Bay submerged aquatic vegetation water
quality and habitat-based requirements and restoration
targets: A second technical synthesis. CBP/TRS 245/00.
EPA/903/R-00/014. Annapolis, MD: U.S. Environmental
Protection Agency, Chesapeake Bay Program.
Chesapeake Bay Program. 2007. Bay trends & indicators:
Bay grass abundance (bay-wide). Accessed November 2007.
EcoCheck. 2007. Chesapeake Bay habitat health report
card: 2006. NOAA Chesapeake Bay Program Office and
University of Maryland Center for Environmental Sci-
ences, Integration and Application Net-work.
Kemp, W.M., W.R. Boynton, R.R. Twilley, J.C. Steven-
son, and L.G. Ward. 1984. Influences of submersed vascular
plants on ecological processes in upper Chesapeake Bay. In:
VS. Kennedy, ed. Estuaries as filters. New York: Academic
Press, pp. 367-394.
Moore, K.A., DJ. Wilcox, B. Anderson, T.A. Parham,
and M.D. Naylor. 2004. Historical analysis of SAV in the
Potomac River and analysis of bay-wide historic SAV to
establish a new acreage goal. Report to EPA Chesapeake
Bay Program,
Orth, R.J., DJ. Wilcox, L.S. Nagey, A.L. Owens, J.R.
Whiting, and A. Serio. 2004. 2003 distribution of sub-
merged aquatic vegetation in Chesapeake Bay and coastal
bays. Report to EPA Chesapeake Bay Program.
VIMS (Virginia Institute of Marine Science). 2007. Bay
grasses (SAV) in Chesapeake Bay and Delmarva Peninsula
coastal bays,
EPA's 2008 Report on the Environment
3-47
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INDICATOR
Hypoxia in the Gulf of Mexico and Long Island Sound
Nutrient pollution is one of the most pervasive problems
facing U.S. coastal waters, with more than half of the
nation's estuaries experiencing one or more symptoms of
eutrophication (Bricker et al., 1999; NRC, 2000; U.S.
Commission on Ocean Policy, 2004). One symptom is low
levels of dissolved oxygen (DO), or hypoxia. Hypoxia can
occur naturally, particularly in areas where natural physi-
cal and chemical characteristics (e.g., salinity or mixing
parameters) limit bottom-water DO. The occurrence of
hypoxia in shallow coastal and estuarine areas appears to
be increasing, however, and is most likely accelerated by
human activities (Jickells, 1998; Vitousek et al., 1997).
This indicator tracks trends in hypoxia in the Gulf of
Mexico and Long Island Sound, which are prime examples
of coastal areas experiencing hypoxia. For consistency, this
indicator focuses on occurrences of DO below 2 milli-
grams per liter (mg/L), but actual thresholds for "hypoxia"
and associated effects can vary over time and space.
Hypoxia often is defined as a concentration of DO below
saturation, and because saturation levels vary with temper-
ature and salinity, the concentration that defines hypoxia
•will vary seasonally and geographically. Effects of hypoxia
on aquatic life also vary, as some organisms are more sensi-
tive to low DO than others. As a general rule, however,
concentrations of DO above 5 mg/L are considered sup-
portive of marine life, while concentrations below this are
potentially harmful. At about 3 mg/L, bottom fishes may
start to leave the area, and the growth of sensitive species
such as crab larvae is reduced. At 2.5 mg/L, the larvae of
less sensitive species of crustaceans may start to die, and the
growth of crab species is more severely limited. Below 2
mg/L, some juvenile fish and crustaceans that cannot leave
the area may die, and below 1 mg/L, fish totally avoid the
area or begin to die in large numbers (Howell and Simp-
son, 1994; U.S. EPA, 2000).
The Gulf of Mexico hypoxic zone on the Texas-Louisiana
Shelf is the largest zone of coastal hypoxia in the Western
Hemisphere (CAST, 1999). It exhibits seasonally low oxygen
levels as a result of complicated interactions involving excess
nutrients carried to the Gulf by the Mississippi and Atchafa-
laya Rivers; physical changes in the river basin, such as chan-
neling, construction of dams and levees, and loss of natural
•wetlands and riparian vegetation; and the stratification in the
•waters of the northern Gulf caused by the interaction of fresh
river water and the salt water of the Gulf (CENR, 2000;
Rabalais and Turner, 2001). Increased nitrogen and phos-
phorus inputs from human activities throughout the basin
support an overabundance of algae, which die and fall to the
sea floor, depleting oxygen in the water as they decompose.
Fresh water from the rivers entering the Gulf of Mexico
forms a layer of fresh water above the saltier Gulf waters and
prevents re-oxygenation of oxygen-depleted water along
the bottom.
Exhibit 3-31. Extent of dissolved oxygen less
than 2.0 mg/L in Gulf of Mexico bottom waters
in mid-summer, 1985-20073
10,000
8,000
ST 6,000
I 4,000
2,000
0
,
90 '92 '94 '96
Year
'00 '02 '04 '06
aOnly 15 square miles were affected in 1988. No data were collected
in 1989.
Data source: LUMCON, 2007a,b
In Long Island Sound, seasonally low levels of oxygen
usually occur in bottom waters from mid-July though Sep-
tember, and are more severe in the western portions of the
Sound, \vhere the nitrogen load is higher and stratification
is stronger, reducing mixing and re-oxygenation processes
(Welsh et al., 1991). While nitrogen fuels the growth of
microscopic plants that leads to low levels of oxygen in the
Sound, temperature, wind, rainfall, and salinity can affect
the intensity and duration of hypoxia.
Data for the two water bodies are presented separately
because they are collected through two different sampling
programs, each with its own aims and technical approach.
The Gulf of Mexico survey is conducted by the Louisi-
ana Universities Marine Consortium (LUMCON) and is
designed to measure the extent of bottom-water hypoxia
in the summer, with samples collected during a cruise that
generally occurs over a 5-day period in mid- to late July
(LUMCON, 2007b). Samples are collected day and night
along several transects designed to capture the overall extent
of the hypoxic zone. The number of locations varies from
60 to 90 per year, depending on the length of the sampling
cruise, the size of the hypoxic zone, logistical constraints,
and the density of station locations. Long Island Sound
sampling is conducted by the Connecticut Department of
Environmental Protection's Long Island Sound Water Qual-
ity Monitoring Program, and is designed to determine both
the maximum extent and the duration of hypoxia (Connect-
icut DEP, 2007). Sampling is performed every month from
October to May and every 2 weeks from June to September
at a set of fixed locations throughout the Sound. All Long
Island Sound samples are collected during the day.
3-48
EPA's 2008 Report on the Environment
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INDICATOI
Hypoxia in the Gulf of Mexico and Long Island Sound (continued)
Sabi
What the Data Show
The size of the midsummer bottom-water
hypoxia area (<2 mg/L DO) in the North-
ern Gulf of Mexico has varied considerably
since 1985, ranging from 15 square miles in
1988 (a drought year in the Mississippi Basin)
to approximately 8,500 square miles in 2002
(Exhibit 3-31). The unusually low areal extent
in 2000 also was associated with very low
discharge from the Mississippi River (see the N
and P Loads in Large Rivers indicator, p. 3-17).
In the latest year of sampling, 2007, the hypoxic
zone measured 7,900 square miles, roughly the
size of New Jersey (Exhibits 3-31 and 3-32).
Over the full period of record (1985-2007), the
area with DO less than 2 mg/L has averaged
approximately 5,200 square miles.
The maximum extent and duration of hypoxic events
(<2 mg/L DO) in Long Island Sound also has varied
considerably since the 1980s (Exhibit 3-33). Since 1987,
Exhibit 3-32. Dissolved oxygen less than 2.0 mg/L in Gulf of
Mexico bottom waters, July 21-28, 2007
Dissolved oxygen:
• <2.0 mg/L
Miles
^•=1
0 15 30 45 60
A
N
Data source: LUMCON, 2007b
Exhibit 3-33. Maximum extent and duration
of dissolved oxygen less than 2.0 mg/L in
Long Island Sound bottom waters, 1987-2007
A. Extent of dissolved oxygen less than 2.0 mg/L
250
200
~T 150
re
o
< 100
50
0
-r-r
lulld
90 '92 '94 '96 '98 '00 '02 '04 '06
Year
B. Duration of dissolved oxygen less than 2.0 mg/L
.
60
40
20
'90 '92 '94 '96 '98 '00 '02 '04 '06
Year
Data source: U.S. EPA, 2007
the largest area of DO less than 2 mg/L was 212 square
miles, which occurred in 1994; the smallest area, 2 square
miles, occurred in 1997 (panel A). The shortest hypoxic
event was 6 days in 1990 and the longest was 71 days, in
1989 (panel B). In 2007, the latest year for which data are
available, the maximum area and duration of DO less than
2 mg/L in Long Island Sound were 31 square miles and 9
days, respectively, with the lowest DO levels occurring in
the \vestern end of the Sound (Exhibits 3-33 and 3-34).
Between 1987 and 2007, the average annual maximum
\vas 68 square miles and 32 days.
Indicator Limitations
Gulf of Mexico:
• This indicator is based on a survey conducted over a
5-day period when hypoxia is expected to be at its maxi-
mum extent. The indicator does not capture periods of
hypoxia or anoxia (no oxygen at all) occurring at times
other than the mid-summer surveys.
• Because the extent of hypoxia is measured through a
single mid-summer sampling cruise, duration cannot
be estimated.
• This indicator does not track vertical extent of hypoxia
or anoxic volume.
• Surveys usually end offshore from the Louisiana-Texas state
line; in years when hypoxia extends onto the upper Texas
coast, the spatial extent of hypoxia is underestimated.
Long Island Sound:
• Hypoxic or anoxic periods that may occur between the
2-week surveys are not captured in the indicator.
• Samples are taken in the daytime, approximately 1 meter
off the bottom. This indicator does not capture oxygen
conditions at night (which may be lower because of the
lack of photosynthesis) or conditions near the sediment-
water interface.
EPA's 2008 Report on the Environment
3-49
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INDICATOI
Hypoxia in the Gulf of Mexico and Long Island Sound (continued)
Exhibit 3-34. Dissolved oxygen in Long Island Sound bottom
waters, July 30-August 1, 2007
CONNECTICUT
New Haven
New London
York
City
Dissolved oxygen:
H<1.0mg/L
• 1.0to<2.0mg/L
• 2.0to<3.0mg/L
• 3.0to<3.5mg/L
Miles
Sample location | ^^__iviiies_^ A
0~~5 1(M5 20^5 N
Data source: Connecticut DEP, 2007
Data Sources
Maps and summary data from the 2007 Gulf of Mexico
survey are published online (LUMCON, 2007b). Data from
prior years were provided by LUMCON (2007a).
Data on the extent and duration of hypoxia in Long Island
Sound have not been published, but were compiled by
EPA's Long Island Sound Office (U.S. EPA, 2007). Con-
centration maps are available online (Connecticut DEP,
2007)—including the 2007 map shown in Exhibit 3-34.
References
Bricker, S.B., C.G. Clement, D.E. Pirhalla, S.P. Orlando,
and D.R.G. Farrow. 1999. National eutrophication assess-
ment: Effects of nutrient enrichment in the nation's estuar-
ies. Silver Spring, MD: NOAA National Ocean Service.
CAST (Council for Agricultural Science and Technology).
1999. Gulf of Mexico hypoxia: Land and sea interactions.
Task force report no. 134.
CENR (Committee on Environment and Natural
Resources). 2000. Integrated assessment of hypoxia in the
northern Gulf of Mexico. Washington, DC: National Sci-
ence and Technology Council Committee on Environment
and Natural Resources,
Connecticut DEP (Department of Envi-
ronmental Protection). 2007. Long Island
Sound Water Quality Monitoring. Accessed
2007.
Howell, P., and D. Simpson. 1994. Abun-
dance of marine resources in relation to
dissolved oxygen in Long Island Sound.
Estuaries 17:394-402.
Jickells, T.D. 1998. Nutrient biogeochemis-
try of the coastal zone. Science 281:217-221.
LUMCON (Louisiana Universities Marine
Consortium). 2007a. Data provided to
ERG (an EPA contractor) by Nancy
Rabalais, LUMCON. August 28, 2007.
LUMCON. 2007b. Hypoxia in the north-
ern Gulf of Mexico. Accessed August 2007.
NRC (National Research Council). 2000.
Clean coastal waters: Understanding and
reducing the effects of nutrient pollution. Washington,
DC: National Academies Press.
Rabalais, N.N., and R.E. Turner, eds. 2001. Coastal
hypoxia: Consequences for living resources and ecosys-
tems. Coastal and estuarine studies 58. Washington, DC:
American Geophysical Union.
U.S. Commission on Ocean Policy. 2004. An ocean blue-
print for the 21st century. Final report. Washington, DC.
U.S. EPA (United States Environmental Protection
Agency). 2007. Data provided to ERG (an EPA contrac-
tor) by Mark Tedesco, EPA Long Island Sound Office.
September 10, 2007.
U.S. EPA. 2000. Ambient aquatic life water quality criteria
for dissolved oxygen (salt-water): Cape Cod to Cape Hat-
teras. EPA/822/R-00/12.
Vitousek, P.M., J.D. Aber, R.W Howarth, G.E. Likens,
PA. Matson, D.W Schindler, WH. Schlesinger, and D.G.
Tilman. 1997. Human alteration of the global nitrogen cycle:
Sources and consequences, ecological applications. Ecol. Appl.
7(3):737-750.
Welsh, B.L., and EC. Eller. 1991. Mechanisms control-
ling summertime oxygen depletion in western Long Island
Sound. Estuaries 14:265-278.
3-50
EPA's 2008 Report on the Environment
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3.5.3 Discussion
What These Indicators Say About Trends in
the Extent and Condition of Coastal Waters
and Their Effects on Human Health and the
Environment
Extent
Although the ROE indicators do not characterize the extent
of all coastal waters, the Wetlands indicator (p. 3-32) shows
that at least one type of coastal system has experienced
changes in extent over the last half-century. The number
of acres of marine and estuarine wetlands has decreased
overall since the 1950s, although the rate of loss has slowed
in recent years. While the indicator does not identify the
exact stressors responsible for the decline in marine and
estuarine wetlands, it does list several factors that have led
to overall wetland loss, including development and conver-
sion to deep-water. Section 3.4 provides further detail on how
human activities can affect wetland extent, including human
activities that exacerbate natural processes (e.g., storm dam-
age). Ultimately, trends in wetland extent affect ecological
systems, as described further below.
Condition
Together, these indicators cover much of the spectrum of
"condition," including three of the broad themes introduced
in Section 3.5.1: nutrients, toxic chemical contaminants,
and the condition of native populations and their habitat. As
described in Section 3.5.1, excess nutrients can cause algal
blooms that result in low dissolved oxygen and reduced water
clarity, which in turn can harm plant and animal commu-
nities. For example, the Trophic State of Coastal Waters
indicator (p. 3-38) shows elevated levels of nutrients and
chlorophyll-a (a surrogate for algal abundance) in a small
but substantial portion of the nation's estuarine areas. These
results are consistent with indicators that show evidence of
eutrophication, such as decreased water clarity and hypoxia.
The SAV in Chesapeake Bay indicator (p. 3-46) in turn offers
an example of an ecological effect linked to eutrophication.
Nutrient stressors cannot be attributed entirely to human
activities; for example, the Gulf of Mexico hypoxic zone
results in part from natural mixing parameters, and trends in
the extent of hypoxic zones show large year-to-year variations
related to factors like climate (Hypoxia in Gulf of Mexico and
Long Island Sound indicator, p. 3-48). However, as the spatial
distribution of hypoxia in Long Island Sound suggests, the
nation's coastal waters can experience eutrophic effects that
are very closely related to human activities (e.g., runoff from
impervious surfaces or combined sewer overflows in an urban
area). Further, as the SAV in Chesapeake Bay indicator (p.
3-46) shows, present conditions may be quite different from
historical reference conditions.
Overall, levels of toxic chemical contaminants are low in most
of the nation's estuarine sediments, but as the Coastal Sedi-
ment Quality indicator (p. 3-42) shows, condition can vary
greatly from one region to the next. In some EPA Regions, as
much as 20 percent of estuarine area has sediments that either
exceed contamination reference standards or fail a screening
test for benthic toxicity. Other indicators discuss the extent
to which toxic contaminants may be entering and affecting
the food web. For example, benthic communities—which are
most directly impacted by contaminants in sediment—show
evidence of disturbance in roughly one-third of U.S. estuar-
ies (e.g., losses of pollution-sensitive species) (Coastal Benthic
Communities indicator, p. 3-44). Fish tissues had at least one
contaminant above human health guidelines in 22 percent
of estuarine sampling sites (Coastal Fish Tissue indicator,
p. 3-61), suggesting that bioaccumulation of certain toxic
compounds is -widespread and, in some instances, could pose
risks to human health. This indicator suggests the importance
of atmospheric deposition of mercury as a stressor to coastal
•water condition, as well as historical activities that released
PCBs and DDT into upstream and coastal -waters.
In ecological terms (populations, communities, and habitat),
trends in the condition of coastal -waters vary. Benthic com-
munities in most of the nation's estuaries are intact in terms
of species diversity (Coastal Benthic Communities indica-
tor, p. 3-44), -which is critical because these organisms are a
fundamental link in the coastal food web. Other populations,
however, may be substantially lower than historical levels as
a result of human stressors—for example, the Chesapeake
Bay's SAV, -which is vulnerable to changes in -water clarity
(SAV in Chesapeake Bay indicator, p. 3-46). SAV is ecologi-
cally important because it is not just a plant population; it
also provides habitat and facilitates nutrient cycling, much
like -wetlands do. SAV has recently shown increases in extent,
•which may translate into increased habitat and breeding
grounds for various species. However, coastal habitat still con-
tinues to be threatened by human stressors. As the Hypoxia
in Gulf of Mexico and Long Island Sound indicator (p. 3-48)
shows, large areas of some of the nation's coastal water bodies
are unsuitable for fish and shellfish populations for at least a
portion of the year.
Limitations, Gaps, and Challenges
Although the seven indicators discussed here provide a good
overview of many important aspects of coastal extent and
condition, there are a few key limitations to their temporal
and spatial coverage. For example, the four indicators derived
from the National Coastal Condition Report do not provide
information about trends over time, as there are insufficient
data from previous surveys to compare -with recent data to
examine potential trends.22 Another temporal limitation is
that many surveys are conducted during an index period, not
over a full year; thus, they may not capture phenomena that
occur outside the sampling window.23 Spatially, the National
22 U.S. Environmental Protection Agency. 2004. National coastal condition
report II. EPA/620/R-03/002.
Ibid.
EPA's 2008 Report on the Environment
3-51
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Indicators are limited because they do not include data from
Alaska, Hawaii, and most U.S. territories. Alaska contains 75
percent of the bays, sounds, and estuarine surface area in the
United States, while Hawaii, the Caribbean, and the Pacific
territories represent a set of unique estuarine subsystems (i.e.,
coral reefs and tropical bays) that are not common in the
contiguous 48 states.
One challenge in assessing coastal waters is that some aspects
of condition vary naturally from one area to another. For
example, some rivers naturally carry a heavy load of sediments
or nutrients into coastal waters, while benthic community
structure may depend on climate, depth, and geology. To
assess coastal waters with respect to natural background condi-
tions, several of the ROE indicators use different reference
conditions for different regions.
To assess the extent and condition of coastal waters more fully,
it would help to have more information in several key areas,
including:
• More information about the extent of coastal waters—e.g.,
an indicator on coastal subsidence.
• Nationally consistent data on coastal water pollutants
beyond those associated with trophic state—for example,
organics, toxics, metals, and pathogens.
• Consistent data on the occurrence of harmful algal blooms,
•which can be caused by many different species of algae.
• A National Indicator of invasive species, which are often
transported from one area to another along shipping routes
or via aquaculture. Little information exists on a national
level, in part because of a lack of standard invasion metrics.
• Comprehensive information on the condition of the
nation's coral reefs—a unique and fragile habitat—and the
status of coastal fish and shellfish communities.24
3.6 What Are the Trends
in the Quality of Drinking
Water and Their Effects
on Human Health?
3.6.1 Introduction
The average American consumes 1 to 2 liters of drinking
•water per day, including water used to make coffee, tea, and
other beverages.25 Virtually all drinking water in the United
States comes from fresh surface water and ground water.
Large-scale water supply systems tend to rely on surface water
U.S. Environmental Protection Agency. 2004. National coastal condition
report II. EPA/620/R-03/002.
' U.S. Environmental Protection Agency. 1997. Exposure factors handbook.
Volume I—general factors. EPA/600/P-95/002Fa.
resources such as lakes, rivers, and reservoirs; these include
the systems serving many large metropolitan areas. Smaller
systems are more likely to use ground water, particularly
in regions with limited surface water resources. Slightly
more than half of the nation's population receives its drink-
ing \vater from ground water, i.e., through wells drilled into
aquifers26 (including private wells serving about 15 percent of
U.S. households27). If drinking water contains unsafe levels
of contaminants, this contaminated water can cause a range
of adverse human health effects. Among the potential effects
are gastrointestinal illnesses, nervous system or reproductive
effects, and chronic diseases such as cancer.
Surface -waters and aquifers can be contaminated by various
agents, including microbial agents such as viruses, bacteria,
or parasites (e.g., E. coli, Cryptosporidium, or Giardia); chemical
contaminants such as inorganic metals, volatile organic com-
pounds (VOCs), and other natural or manmade compounds; and
radionuclides, which may be manmade or naturally occurring.
Contaminants also can enter drinking -water between the treat-
ment plant and the tap (for example, lead can leach into -water
from old plumbing fixtures or household or street-side pipes).
Drinking -water contaminants can come from many sources:
• Human activities that contaminate the source.
Aquifers and surface -waters that provide drinking -water
can be contaminated by many sources, as discussed in Sec-
tions 3.2 and 3.3. For example, chemicals from disposal
sites or underground storage facilities can migrate into
aquifers; possible contaminants include organic solvents
(e.g., some VOCs), petroleum products, and heavy metals.
Contaminants can also enter ground -water or surface -water
as a result of their application to the land. Pesticides and
fertilizer compounds (e.g., nitrate) can be carried into lakes
and streams by rainfall runoff or snowmelt, or percolate
through the ground and enter aquifers. Industrial -wastes
can contaminate drinking -water sources if injected into
containment wells or discharged into surface -waters, as can
mine -waste (e.g., heavy metals) if not properly contained.
• Natural sources. As ground -water travels through rock
and soil, it can pick up naturally occurring contaminants
such as arsenic, other heavy metals, or radionuclides.
Some aquifers are naturally unsuitable for drinking
because the local geology happens to include high levels of
certain contaminants.
• Microbial pathogens. Human -wastes from sewage and
septic systems can carry harmful microbes into drinking
•water sources, as can -wastes from animal feedlots and -wild-
life. Major contaminants include Giardia, Cryptosporidium,
and E. coli O157:H7. Coliform bacteria from human and
animal -wastes also may be found in drinking -water if the
•water is not properly finished; these bacteria may indicate
that other harmful pathogens are present as well.
US. Geological Survey. 1999. Ground water (general interest publication).
27 U.S. Environmental Protection Agency. 2002.The clean water and drinking
water infrastructure gap analysis. EPA/816/R-02/020.
3-52
EPA's 2008 Report on the Environment
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• Treatment and distribution. While treatment can
remove many chemical and biological contaminants from
the water, it may also result in the presence of certain
disinfection byproducts that may themselves be harmful,
such as trihalomethanes. Finished water can also become
contaminated after it enters the distribution system, either
from a breach in the system or from corrosion of plumb-
ing materials, particularly those containing lead or copper.
After water leaves the treatment plant, monitoring for lead
in drinking water is done at the tap, and monitoring for
microbial contaminants (as well as disinfection byproducts)
occurs within the distribution system.
Chemical exposure through drinking water can lead to a
variety of long- and short-term effects. Potential health effects
of exposure to certain metals, solvents, and pesticides can
include chronic conditions such as cancer, which can develop
over long periods of time (up to 70 years). Higher doses over
shorter periods of time can result in a variety of biological
responses, including toxicity, mutagenicity, and teratogenic-
ity (birth defects). Short-term results might include cosmetic
effects (e.g., skin discoloration), unpleasant odors, or more
severe problems such as nervous system or organ damage and
developmental or reproductive effects. The effects of some
drinking water contaminants are not yet well understood. For
example, certain disinfection byproducts have been associated
•with cancer, developmental, and reproductive risks, but the
extent of this association is still uncertain.
Consuming water with pathogenic microbes can cause life-
threatening diseases such as typhoid fever or cholera—rare in
the U.S. today—as well as more common waterborne diseases
caused by organisms such as Giardia, Cryptosporidium, E. coli,
and Campylobacter. Health consequences of the more common
illnesses can include symptoms such as gastrointestinal distress
(stomach pain, vomiting, diarrhea), headache, fever, and kidney
failure, as well as various infectious diseases such as hepatitis.
A number of factors determine whether the presence of con-
taminants in drinking water will lead to adverse health effects.
These include the type of contaminant, its concentration in
the water, individual susceptibility, the amount of contami-
nated water consumed, and the duration of exposure.
Disinfection of drinking water—the destruction of pathogens
using chlorine or other chemicals—has dramatically reduced
the incidence of waterborne diseases such as typhoid, cholera,
and hepatitis, as well as gastrointestinal illness, in the United
States. Other processes required depend on the physical,
microbiological, and chemical characteristics and the types
of contaminants present in the source water (e.g., filtration to
remove turbidity and biological contaminants, treatment to
remove organic chemicals and inorganic contaminants such as
metals, and corrosion control to reduce the presence of corro-
sion byproducts such as lead at the point of use).
3.6.2 ROE Indicators
This section presents an indicator that tracks trends in the total
population served by community water systems for which
states report no violations of health-based drinking water
standards (Table 3-6). Data for this indicator come from EPA's
Safe Drinking Water Information System, Federal Version.
This system houses all data submitted by states, EPA Regions,
and the Navajo Nation Indian Tribe on the community water
systems they oversee.
Table 3-6. ROE Indicators of Trends in the Quality of Drinking Water
and Their Effects on Human Health
National Indicators
Population Served by Community Water Systems with No Reported
Violations of Health-Based Standards (N/R)
Section
3.6.2
3-54
N/R = National Indicator displayed at EPA Regional scale
EPA's 2008 Report on the Environment
3-53
-------
INDICATO
Population Served by Community Water Systems with No
Reported Violations of Health-Based Standards
100
, 90
'• 80
I ^O
' 60
: 50
; 40
: 30
; 20
• 10
0
Community water systems (CWS), public
•water systems that supply water to the
same population year-round, served over 286
million Americans in fiscal year (FY) 2007
(U.S. EPA, 2007)—roughly 95 percent of
the U.S. population (U.S. Census Bureau,
2007). This indicator presents the percentage
of Americans served by CWS for which states
reported no violations of EPA health-based
standards for over 90 contaminants (U.S.
EPA, 2004b).
Health-based standards include Maximum
Contaminant Levels (MCLs) and Treatment
Techniques (TTs). An MCL is the highest level
of a contaminant that is allowed in drinking
•water. A TT is a required treatment process
(such as filtration or disinfection) intended
to prevent the occurrence of a contaminant
in drinking water (U.S. EPA, 2004c). TTs
are adopted where it is not economically or
technologically feasible to ascertain the level of
a contaminant, such as microbes, where even
single organisms that occur unpredictably or
episodically can cause adverse health effects.
Compliance with TTs may require finished
•water sampling, along with quantitative or
descriptive measurements of process perfor-
mance to gauge the efficacy of the treatment
process. MCL-regulated contaminants tend
to have long-term rather than acute health
effects, and concentrations vary seasonally (if at
all; e.g., levels of naturally occurring chemical
contaminants or radionuclides in ground water
are relatively constant). Thus, compliance is
based on averages of seasonal, annual, or less
frequent sampling.
This indicator tracks the population served by CWS for
•which no violations were reported to EPA for the period
from FY 1993 to FY 2007, the latest year for which data
are available. Results are reported as a percentage of the
overall population served by CWS, both nationally and
by EPA Region. This indicator also reports the number
of persons served by systems with reported violations of
standards covering surface water treatment, microbial
contaminants (microorganisms that can cause disease), and
disinfection byproducts (chemicals that may form when
disinfectants, such as chlorine, react with naturally occur-
ring materials in water and may pose health risks) (U.S.
EPA, 2004b). The indicator is based on violations reported
quarterly by states, EPA, and the Navajo Nation Indian
Tribe, who each review monitoring results for the CWS
that they oversee.
Exhibit 3-35. U.S. population served by community water
systems with no reported violations of EPA health-based
standards, fiscal years 1993-20073
'93 '94 '95 '96 '97
'99 '00 '01
Fiscal year
'02 '03 '04 '05 '06 '07
Reported violations:
| New standards
(post-12/31/01) only
None
Coverage: U.S. residents served by community
water systems (CWS) (approximately 95% of
the total U.S. population).
bSeveral new standards went into effect after
12/31/01, including the Interim Enhanced
Surface Water Treatment Rule (CWS with
surface water sources serving 10,000 or more
people) and the Disinfection Byproducts (DBP) Rule for CWS that disinfect. In FY
2003, the DBP rule applied to systems serving >10,000 people; as of January 2004,
it applied to all CWS. For FY 2002-2007, each column is divided into two segments:
the lower portion reflects all standards in place at the time, while the upper portion
covers sytems with reported violations of new standards but not pre-12/31/01
standards. Adding both segments together, the total height of each column indicates
what percent of CWS customers would have been served by CWS with no reported
violations if the new standards had not gone into effect.
Data source: U.S. EPA, 2007
What the Data Show
Of the population served by CWS nationally, the percent-
age served by systems for which no health-based violations
•were reported for the entire year increased overall from
79 percent in 1993 to 92 percent in FY 2007, with a peak
of 94 percent in FY 2002 (Exhibit 3-35). This indicator is
based on reported violations of the standards in effect in
any given year. Several new standards went into effect after
December 31, 2001. These were the first new drinking
•water standards to take effect during the period of record
(beginning in 1993). The results after FY 2001 would have
been somewhat higher had it not been for violations of
standards that became effective in FY 2002 or after
(Exhibit 3-35; see the dark segment atop the columns
starting in FY 2002). As EPA adds to or strengthens its
requirements for water systems over time, compliance with
standards comes to represent a higher level of public health
protection.
3-54
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Population Served by Community Water Systems with No
Reported Violations of Health-Based Standards (continued)
Exhibit 3-36. U.S. population served by
community water systems with no reported
violations of EPA health-based standards, by
EPA Region, fiscal years 1993-2007ab
30
-R2
-R3
R4
-R5
R6
R7
R8
-R9
-R10
-Nat'l
'93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07
Fiscal year
Coverage: U.S. residents served
by community water systems
(CWS) (approximately 95% of
the total U.S. population).
bBased on reported violations of
the standards in effect in any
given year.
Data source: U.S. EPA, 2007
When results are broken down by EPA Region, some
variability over time is evident (Exhibit 3-36). Between
FY 1993 and FY 2007, most Regions were consistently
above the national percentage. Three of the Regions were
substantially below the national average over much of
the period of record, but as of FY 2007, only one Region
remained well below the national percentage, largely
because of a small number of public water systems serving
large populations.
In FY 2007, reported violations involving surface water
treatment rules in large CWS were responsible for exceed-
ing health-based standards for 8.9 million people (3.1 per-
cent of the population served by CWS nationally) (Exhibit
3-37). Reported violations of heath-based coliform
standards affected 10.6 million people (3.7 percent of the
CWS-served population), and reported violations of the
health-based disinfection byproducts standards (Stage 1)
affected 3.6 million people (1.3 percent of the CWS-served
population). Overall, of the 8.5 percent of the population
served by systems with reported violations in FY 2007,
84 percent of these cases involved at least one of these
three rules governing treatment to prevent waterborne
diseases—the most -widespread and acute threat to health
Exhibit 3-37. U.S. population served by
community water systems with reported
violations of EPA health-based standards, by
type of violation, fiscal year2007a
Percent of
Population served CWS customers
Any violation
Selected violations
Stage 1 Disinfection
Byproducts Rule
Surface Water
Treatment Rules
Total Coliform Rule
Any of these
selected rules
24,279,892
3,643,104
8,945,673
10,569,935
20,472,902
8.5
1.3
3.1
3.7
7.1
Coverage: U.S. residents served by community water systems
(CWS) (approximately 95% of the total U.S. population).
bSome CWS violated more than one of the selected rules.
Data source: U.S. EPA, 2007
from drinking water—or the contaminants created by such
treatment.
Indicator Limitations
• Non-community water systems (typically relatively small
systems) that serve only transient populations such as
restaurants or campgrounds, or serving those in a non-
domestic setting for only part of their day (e.g., a school,
religious facility, or office building), are not included in
population served figures.
• Domestic (home) use of drinking water supplied by pri-
vate wells—which serve approximately 15 percent of the
U.S. population (USGS, 2004)—is not included.
• Bottled water, which is regulated by standards set by the
Food and Drug Administration, is not included.
• National statistics based on population served can be
volatile, because a single very large system can sway
the results by up to 2 to 3 percent; this effect becomes
more pronounced when statistics are broken down at the
regional level, and still more so for a single rule.
• Some factors may lead to overstating the extent of
population receiving water that violates standards. For
example, the entire population served by each system in
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INDICATOR
Population Served by Community Water Systems with No
Reported Violations of Health-Based Standards (continued)
violation is reported, even though only part of the total
population served may actually receive water that is out
of compliance. In addition, violations stated on an annual
basis may suggest a longer duration of violation than may
be the case, as some violations may be as brief as an hour
or a day.
• Other factors may lead to understating the popula-
tion receiving water that violates standards. CWS that
purchase water from other CWS are not always required
to sample for all contaminants themselves, and the CWS
that are -wholesale sellers of water generally do not report
violations for the population served by the systems that
purchase the water.
• Under-reporting and late reporting of violations by
states to EPA affect the ability to accurately report the
national violations total. For example, EPA estimated
that between 1999 and 2001, states were not reporting
35 percent of all health-based violations, which reflects a
sharp improvement in the quality of violations data com-
pared to the previous 3-year period (U.S. EPA, 2004a).
• State data verification and other quality assurance analy-
ses indicate that the most -widespread data quality prob-
lem is under-reporting of monitoring and health-based
violations and inventory characteristics. Under-reporting
occurs most frequently in monitoring violations; even
though these are separate from the health-based viola-
tions covered by the indicator, failures to monitor could
mask violations of TTs and MCLs.
Data Sources
Data for this indicator -were obtained from EPA's Safe
Drinking Water Information System (U.S. EPA, 2007)
(http://www.epa.gov/safewater/data/getdata.html;
http://www.epa.gov/safewater/data/pivottables.html). This
database contains a record of violations reported to EPA by
the states or other entities that oversee CWS, along -with
annual summary statistics.
References
U.S. Census Bureau. 2007. Monthly Population Estimates
for the United States: April 1, 2000 to September 1, 2007.
NA-EST2006-01. Accessed October 2007. .
Available from
U.S. EPA (United States Environmental Protection
Agency). 2007. Safe Drinking Water Information System,
Federal Version. Accessed October 2007.
U.S. EPA. 2004a. Safe Drinking Water Act 30th anni-
versary fact sheet: Drinking -water monitoring, compli-
ance, and enforcement,
U.S. EPA. 2004b. Safe Drinking Water Act 30th anniver-
sary fact sheet: Drinking -water standards and health effects.
U.S. EPA. 2004c. Safe Drinking Water Act 30th anniver-
sary fact sheet: Glossary,
USGS (United States Geological Survey). 2004. Estimated
use of-water in the United States in 2000. 2004 revision.
3.6.3 Discussion
What This Indicator Says About Trends in
the Quality of Drinking Water and Their
Effects on Human Health
Most Americans served by community -water systems (CWS)
are served by facilities -with no reported violations (Drinking
Water indicator, p. 3-54). Since 1993, the percentage of Amer-
icans served by CWS for -which states reported no health-
based violations has increased, although there has been some
reversal nationally since the percentage peaked in 2002. While
there have been noticeable differences among EPA Regions
over the period of record, most Regions have been consis-
tently above 90 percent since 1993. Only one Region has been
consistently below the national average, though according to
the data source, this result is due largely to one large metro-
politan -water system that is under a legal settlement to upgrade
its treatment technology. As this result suggests, -while the
nation has thousands of CWS, a substantial percentage of the
population depends on the quality of a small number of large
metropolitan -water systems.
Limitations, Gaps, and Challenges
As noted in the indicator description, a challenge in assessing
national drinking -water quality is that there are inherent limi-
tations in using reporting data. Some violations may be unre-
ported, particularly if monitoring is inadequate—leading to
undercounting. Other violations may be overlooked because
CWS may purchase -water from other CWS and not test it for
3-56
EPA's 2008 Report on the Environment
-------
all contaminants themselves. Conversely, the data could also
overstate the portion of the population receiving water in vio-
lation of standards, because a violation could be as short as an
hour or a day and could be limited to water received by only a
small portion of a system's customers.
Other challenges relate to the interpretation of the Drinking
Water indicator (p. 3-54). For example, trends can be con-
founded by the fact that water quality standards and treatment
requirements change over time. Thus, an apparent increase in
violations over time may result from new or more stringent
MCLs rather than simply a decline in the quality of drinking
•water, as these new requirements may also affect some systems'
compliance with existing standards.
As described in the indicator summary, the indicator does not
address the quality of drinking water other than that obtained
from CWS. Information that would provide a more complete
characterization of drinking water quality includes National
Indicators for:
• Trends in drinking water quality from CWS that did
have reported violations. The Drinking Water indicator
does not explain the nature of every reported violation, nor
does it show how many contaminants may be above stan-
dards, the identity of the contaminants, the extent to which
standards were exceeded, or the duration of the violations
(some of \vhich, especially in larger systems, were only a
very few hours in length).
• The quality of drinking water from other public
•water systems. There is no ROE indicator for drink-
ing \vater quality from transient and non-transient non-
community \vater systems, -which are required to monitor
quality and report violations to state authorities, but are
regulated only for certain contaminants.
• The quality of drinking water from non-public
-water supplies. Private wells, cisterns, and other non-
public -water supplies are not subject to federal regulation.
Some private supplies are treated, and some people do test
their private -water for common contaminants. However,
no national infrastructure, and few if any systematic state
efforts, currently exist to collect data on trends in the qual-
ity of these supplies. Bottled -water is regulated by the U.S.
Food and Drug Administration (FDA), -which is required
by law to apply standards that are no less stringent or pro-
tective of public health than EPA's, but there is no ROE
indicator on the quality of bottled -water.
In addition to these gaps, there are no ROE indicators to
identify trends in health effects of interest, such as waterborne
disease occurrence. Data are very limited for endemic -water-
borne illness as -well as for acute waterborne disease outbreaks.
3.7 What Are the Trends
in the Condition of
Recreational Waters
and Their Effects on
Human Health and the
Environment?
3.7.1 Introduction
The nation's rivers, lakes, and coastal waters are used for many
different forms of recreation. Some recreational activities take
place in or on the water, such as swimming, boating, white-
water rafting, and surfing. Other activities may not involve
contact with the water yet may still require water—or be
enhanced by proximity to water. Examples include a picnic at
the beach, hiking, nature viewing (e.g., bird watching), and
hunting (especially waterfowl). People also engage in fishing
and shellfishing as recreational activities.
In the questions on fresh surface waters and coastal waters
(Sections 3.2 and 3.5), condition is defined as a combination of
physical, chemical, and biological attributes of a water body.
For recreational waters, condition is more specific, focusing on
those physical, chemical, and biological attributes that deter-
mine a water body's ability to support recreational activities.
The particular attributes necessary to support recreation vary
•widely, depending on the nature of the activity in question. In
a more general sense, however, the components of recreational
condition fall into two main categories:
• Attributes that determine whether recreational activi-
ties can be enjoyed without unacceptable risk to human
health—primarily pathogens and chemical contaminants
that can affect the health of humans who are exposed dur-
ing contact activities such as swimming.
• Attributes associated with ecological systems that support
recreation—e.g., the status offish and bird communities, as
•well as chemical and physical characteristics that may affect
these populations and their habitat. These attributes also
contribute to the aesthetic qualities important for recre-
ational activities.
Many stressors affecting the condition of recreational waters
fall into the broad category of contaminants. This category
includes chemical contaminants, various pathogens (viruses,
bacteria, and other parasites or protozoans) that can cause
infectious disease, and pollutants such as trash or debris. These
stressors can come from a variety of point sources and non-
point sources, and can be discharged or washed directly into
EPA's 2008 Report on the Environment
3-57
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recreational waters or carried downstream to lakes or coastal
areas. Among the major sources are storm water and sediment
runoff, direct discharge (e.g., from industrial facilities and
sewer systems), atmospheric deposition, and recreational activ-
ities themselves (e.g., outboard motor exhaust and overboard
discharge of sanitary wastes). Some chemicals and pathogens
occur naturally, but their abundance may be influenced by
other human stressors such as land use and land cover (e.g.,
paved surfaces and forestry and irrigation practices, which
can influence runoffpatterns) or by natural stressors such as
\veather and climate. Land use and land cover can influence
recreational condition in other ways as well.
In terms of human health, the stressors that pose the great-
est potential risks are chemical and biological contaminants.
People can be exposed to these contaminants if they swim in
contaminated waters or near storm water or sewage outfall
pipes—especially after a rainfall event. Boating also may pose
risks of exposure, although to a lesser extent. For toxic chemi-
cal contaminants, the main routes of exposure are through
dermal (skin) contact or accidental ingestion. For pathogens,
the main route of exposure is by swallowing water, although
some infections can be contracted simply by getting polluted
•water on the skin or in the eyes. In some cases, swimmers can
develop illnesses or infections if an open wound is exposed to
contaminated water.
Effects of exposure to chemical and biological contaminants
range from minor illnesses to potentially fatal diseases. The most
common illness is gastroenteritis, an inflammation of the stomach
and the intestines that can cause symptoms such as vomiting,
headaches, and diarrhea. Other minor illnesses include ear, eye,
nose, and throat infections. While unpleasant, most swimming-
related illnesses are indeed minor, with no long-term effects.
However, in severely contaminated waters, swimmers can
sometimes be exposed to serious and potentially fatal diseases
such as meningitis, encephalitis, hepatitis, cholera, and typhoid
fever.28 Children, the elderly, and people with weakened immune
systems are most likely to develop illnesses or infections after
coming into contact with contaminated water.
From an ecological perspective, stressors to recreational waters
can affect habitat, species composition, and important ecologi-
cal processes. For example, changes in land cover (e.g., the
removal of shade trees) may cause water temperature to rise
above the viable range for certain fish species. Hydromodifica-
tions such as dams may create some recreational opportunities
(e.g., boating), but they also may impede the migration offish
species such as salmon. Chemical and biological contaminants
may harm plants and animals directly, or they may disrupt the
balance of the food web. For example, acid deposition may
lead to acidification in lakes, while excess nutrients can lead
to eutrophic conditions such as low levels of dissolved oxygen,
•which in turn can harm fish and shellfish populations. Beyond
their obvious effects on activities like fishing and nature
viewing, stressors such as these also can be detrimental to
recreational activities in a more aesthetic sense, as the presence
Pond, K. 2005. Water recreation and disease—plausibility of associations.
sequelae and mortality. Published on behalf ofWorld Heath Organization.
London, United Kingdom: IWA Publishers,
of dead fish or visibly unhealthy plants may diminish one's
enjoyment of recreation in or near the water.
Ultimately, ecological effects can also impact human health.
For example, eutrophic conditions can encourage harmful
algal blooms—some of which can produce discomfort or ill-
ness \vhen people are exposed through ingestion or skin or eye
contact. One well-known type of harmful algal bloom is "red
tide," \vhich in humans can cause neurotoxic shellfish poison-
ing and respiratory irritation.29
3.7.2 ROE Indicators
At this time, no National Indicators have been identified
to quantify the condition of recreational -waters. Individual
states monitor certain recreational -waters for a set of indica-
tor bacteria and report monitoring results to EPA. However,
the methodology and frequency of data collection vary among
states, so the data are not necessarily comparable.
Challenges and information gaps for developing reliable
National Indicators of recreational -water condition are
described in more detail in Section 3.7.3 below.
3.7.3 Discussion
Limitations, Gaps, and Challenges
Several challenges exist in assessing the condition of the
nation's recreational -waters. Foremost is the lack of a com-
prehensive national system for collecting data on pathogen
levels at beaches, a key concern in assessing the suitability of
recreational -waters -with respect to human health. In addi-
tion, data on the types and extent of health effects associ-
ated -with swimming in contaminated -water are limited.
The number of occurrences is likely under-reported because
individuals may not link common symptoms (e.g., gastroin-
testinal ailments, sore throats) to exposure to contaminated
recreational -waters.
Another challenge to answering this question is the breadth
of the subject. "Recreation" encompasses a -wide range of
activities, involving different types of-water bodies and
entailing varying concepts of condition. While the rec-
reational condition of a -white-water stream -with a native
salmon population -will be determined largely by flow levels
and condition offish habitat, for example, the recreational
condition of a beach -will be assessed more in terms of levels
of pathogens and chemical contaminants.
Gaps in assessing the condition of the nation's recreational
•waters include National Indicators of pathogen levels in recre-
ational -waters (rivers, lakes, and coastal beaches), the magni-
tude of specific stressors—particularly contaminant loadings
(biological and chemical)—to recreational -waters, harmful
algal blooms in recreational -waters, and the condition of rec-
reational fish and shellfish populations.
29 National Research Council. 2000. Clean coastal waters: Understanding and
reducing the effects of nutrient pollution. Washington, DC: National Acad-
emies Press.
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3.8 What Are the Trends
in the Condition of
Consumable Fish and
Shellfish and Their
Effects on Human
Health?
3.8.1 Introduction
Fish and shellfish caught through commercial, recreational, or
subsistence fishing are an important part of a healthful diet for
many people. Fish and shellfish contain high-quality protein and
other essential nutrients, are low in saturated fat, and contain
omega-3 fatty acids. Most fish consumed in the United States
comes from commercial fisheries, and is purchased in supermar-
kets or fish markets. Fishing also is one of the most popular out-
door recreational activities in the country, with more than 34
million people per year fishing recreationally30—many of whom
eat at least some of the fish they catch. In addition, subsistence
fishers—people who rely on fish as an affordable food source
or for whom fish are culturally important—consume fish and
shellfish as a major part of their diets. Commercial, recreational,
and subsistence fisheries all have substantial economic value for
the nation, regions, and local communities.
Americans consume fish and shellfish caught in the nation's
lakes, rivers, and estuaries and in deep ocean fisheries, as well
as farmed fish and shellfish.31 Some of these fish and shellfish
contain elevated levels of chemical or biological contaminants.
This question addresses the condition of consumable fish and
shellfish caught or farmed in the United States—whether, and
the extent to which, these organisms contain contaminants
that could affect the health of people who consume them.
According to recent surveys, the average American con-
sumes close to 13 grams offish and shellfish per day (prepared
•weight), which amounts to slightly more than one 3-ounce
serving per week.32 However, many Americans consume
substantially more fish and shellfish than the national average;
some of the highest consumption rates are among tribal and
ethnic populations who fish for subsistence. Concern about
fish and shellfish safety is higher for these groups as well as for
U.S. Department of the Interior, Fish and Wildlife Service, and U.S. Depart-
ment of Commerce, U.S. Census Bureau. 2002. 2001 national survey offish-
ing, hunting, and wildlife-associated recreation.
According to the National Oceanic and Atmospheric Administration's Fisher-
ies of the United States—2006, imports of edible seafood made up 83 percent
of U.S. per capita consumption in 2006. See
U.S. Environmental Protection Agency. 2002. Estimated per capita fish con-
sumption in the United States. EPA/821/C-02/003.
U.S. and global sources of mercury are described in more detail in Section
2.2, which includes an indicator of domestic mercury emissions.
children, pregnant and nursing women (because of possible
effects on the fetus or infant), and other population subgroups
\vho may be more vulnerable to the health effects of certain
chemical or biological contaminants (e.g., elderly or immuno-
suppressed individuals).
Chemical contaminants of greatest concern in consumable fish
and shellfish tend to be those that are persistent, bioaccumula-
tive, and toxic (called PBTs). These chemicals can persist for
long periods in sediments and then enter the food web when
ingested by bottom-dwelling (benthic) organisms. Benthic
organisms are eaten by small fish, which in turn are eaten by
larger fish, which may be consumed by humans or wildlife.
PBTs that are common in fresh and coastal waters include:
• Mercury. This highly toxic metal is present in waters
all over the globe—a result of long-range transport and
deposition of airborne mercury as well as direct inputs to
•water.33 Mercury in water bodies can be methylated by
certain bacteria in bottom sediments to form methylmer-
cury, \vhich is more toxic and bioavailable than other forms
of mercury.34 It also is biomagnified through aquatic food
•webs, so that it becomes particularly concentrated in larger
and longer-lived predators such as bass, tuna, swordfish,
and some sharks. Exposure to high levels of methylmercury
can cause reproductive and other effects in wildlife;35 in
humans, exposure to elevated levels is primarily associated
•with developmental and neurological health effects.36
• Polychlorinated biphenyls (PCBs) and the pesticide
DDT. Though PCBs and DDT are no longer manufac-
tured or used in the U.S., they persist in historical deposits
in -watersheds and near-shore sediments, which can con-
tinue to contaminate fish and shellfish. These chemicals
are also circulated globally as a result of use in other parts
of the \vorld. Levels of PCBs and DDT are a concern in
some bottom-feeding fish and shellfish, as -well as in some
higher-level predators. These chemicals have been linked to
adverse health effects such as cancer, nervous system dam-
age, reproductive disorders, and disruption of the immune
system in both humans and -wildlife.
Other chemical contaminants that may be present in fish and
shellfish include other pesticides, metals (such as arsenic), and
dioxins and furans.37
Biological contamination also can affect the condition offish
and shellfish—particularly the latter. For example, shellfish
contaminated -with pathogens from human and animal fecal
•wastes can cause gastrointestinal illness and even death in
individuals with compromised immune systems. Sources of
U.S. Environmental Protection Agency. 1997. Mercury study report to
Congress.Volume III: Fate and transport of mercury in the environment.
EPA/452/R-97/005.
U.S. Environmental Protection Agency. 1997. Mercury study report to
Congress.Volume V: Health effects of mercury and mercury compounds.
EPA/452/R-97/007.
National Research Council. 2000.lexicological effects of methylmercury.
Washington, DC: National Academies Press.
U.S. Environmental Protection Agency. In progress. National study of chemi-
cal residues in lake fish tissue,
EPA's 2008 Report on the Environment
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fecal contamination in shellfish include urban runoff, wildlife,
wastewater treatment systems and treatment plants, agricul-
tural runoff, and boating and marinas.
Marine biotoxins produced by certain types of algae can
contaminate fish and shellfish as well. These toxins not only
can harm fish and fish communities—sometimes resulting
in massive fish kills or losses to aquaculture operations—but
they also can make their way through the food web to affect
seabirds, marine mammals, and humans. Mollusks such as
mussels, clams, oysters, whelks, and other shellfish can carry
biotoxins that have common symptoms such as irritation of
the eyes, nose, throat, and tingling of the lips and tongue.
Consumption of contaminated seafood can cause a range of
other health effects in humans, depending on the organism
involved, including gastrointestinal illness, amnesia, memory
loss, paralysis, and even death.38'39
The growth of aquaculture, or fish farming, may affect the
levels of certain contaminants in consumable fish and shell-
fish. Dense colonies can increase stress and disease transmis-
sion among fish, in some cases requiring the administration of
antibiotics.40 Studies have also found higher levels of certain
contaminants in farmed fish than in their wild counterparts,
possibly due to differences in diet. For example, several studies
have found higher concentrations of PCBs, organochlorine
pesticides, and polybrominated diphenyl ethers (PBDEs) in
farmed salmon.41
Overharvesting also can affect the condition offish and shell-
fish—not only the species being harvested, but also the species
that prey on them—by disrupting the food web. Because of
depleted food sources, predators can become more suscep-
tible to disease (such as infection of rockfish by mycobacterial
lesions). These infections are often confined to internal organs
and may not be apparent to anglers, although in some cases
they are associated with external sores as well. Some types of
mycobacteria can also infect humans who handle diseased fish
if the infection comes into contact with an open wound. The
slow-developing infections are usually not severe in humans,
but in some cases they can cause major health problems, espe-
cially in people with compromised immune systems.
3.8.2 ROE Indicators
Two ROE indicators characterize levels of chemical con-
taminants in edible fish and shellfish species (Table 3-7). One
indicator reports levels and occurrence of contaminants in fish
in estuarine areas; the other, in freshwater lakes and reservoirs.
Both indicators are based on nation-wide probabilistic surveys.
The coastal fish indicator is based on an index originally pre-
sented in EPA's second National Coastal Condition Report.
The underlying data were collected between 1997 and 2000
as part of EPA's Environmental Monitoring and Assessment
Program (EMAP). EMAP's probabilistic coastal surveys are
designed to be representative of 100 percent of estuarine acre-
age in the contiguous 48 states. This indicator presents results
by EPA Region.
The other indicator describes contamination offish in inland
lakes. This indicator is derived from fish samples collected and
analyzed for EPA's National Study of Chemical Residues in
Lake Fish Tissue, a probabilistic survey designed to estimate
the national distribution of the mean levels of selected PBT
chemical residues in fish tissue from lakes and reservoirs.
Note that this question does not rely on information about
fish and shellfish consumption advisories. While many states
and tribes issue fish consumption advice and develop fish
advisory programs, there is great variability in how moni-
toring is conducted, how decisions are made to place -waters
under advisory, and -what specific advice is provided -when
contamination is found in fish. Further, trends in the number
of advisories over time may reflect changes in the frequency
and intensity of monitoring.42 Thus, fish advisories cannot
provide a consistent national metric for trends in the condi-
tion of consumable fish and shellfish.
Table 3-7. ROE Indicators of Trends in the Condition of Consumable Fish
and Shellfish and Their Effects on Human Health
National Indicators
Coastal Fish Tissue Contaminants (N/R)
Contaminants in Lake Fish Tissue
Section
3.8.2
3.8.2
3-61
3-63
N/R = National Indicator displayed at EPA Regional scale
Baden D., L.E. Fleming, and J.A. Bean. 1995. Marine toxins. In: DeWolff.
F.A., ed. Handbook of clinical neurology: Intoxications of the nervous system.
Part II: Natural toxins and drugs. Amsterdam,The Netherlands: Elsevier. pp.
141-175.
Van Dolah, EM. 2000. Marine algal toxins: Origins, health effects, and their
increased occurrence. Environ. Health Persp. 108(Suppl 1):133-141.
Barton, B.A., and G.K. Iwama. 1991. Physiological changes in fish from stress
in aquaculture with emphasis of the response and effects of corticosteroids.
Annu. Rev. Fish Dis. 1:3-26.
Easton, M.D.L., D. Luszniak, and E.Von der Geest. 2002. Preliminary exami-
nation of contaminant loadings in farmed salmon, wild salmon and commer-
cial salmon feed. Chemosphere 46(7):1053-1074.
U.S. Environmental Protection Agency. 2005. Fact sheet: National listing of
fish advisories. EPA/823/F-05/004.
3-60
EPA's 2008 Report on the Environment
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Coastal Fish Tissue Contaminants
Contaminants in fish not only affect the fish's own health
and ability to reproduce, but also affect the many spe-
cies that feed on them. Contaminants also may make fish
unsuitable for human consumption (U.S. EPA, 2000).
This indicator, derived from an indicator presented in
EPA's second National Coastal Condition Report (U.S.
EPA, 2004), is based on National Coastal Assessment (NCA)
fish tissue survey data from 653 estuarine sites throughout
the United States. The survey was designed to provide a
national picture of coastal fish tissue contaminants by sam-
pling sites in estuarine waters throughout the contiguous
48 states. Each site was sampled once during the 1997-2000
period, within an index period from July to September. The
indicator reflects average condition in each EPA Region
during this index period. Results were also aggregated and
•weighted by estuarine area for the entire nation.
Fish and shellfish analyzed in the survey included Atlan-
tic croaker, white perch, catfish, flounder, scup, blue crab,
lobster, shrimp, whiffs, mullet, tomcod, spot, weakfish,
halibut, sole, sculpins, sanddabs, bass, and sturgeon. At
each site, five to 10 whole-body fish samples were tested
for 90 contaminants. This indicator is based on data col-
lected from 1997 to 2000.
To assess risks to human health, contaminant concentra-
tions in fish tissue were compared with established EPA
guideline ranges for recreational fishers, which were avail-
able for 16 of the 90 analytes. These guideline ranges are
based on the consumption of four 8-ounce fish meals per
month, and generally reflect non-cancer risks (U.S. EPA,
2000, 2004). For most contaminants, this is done using
•whole-body concentrations; for mercury, which concen-
trates in the edible fillet portion of the fish, a factor of 3.0
•was used to correct whole-body concentrations in order to
approximate fillet concentrations. The 3.0 factor represents
the median value (range 1.5-5.0) found in the available
literature (Windom and Kendall, 1979; Mikac et al, 1985;
Schmidt and Brumbaugh, 1990; Kannan et al., 1998;
Canadian Council of Ministers of the Environment, 1999).
For this indicator, a site was given a high contamina-
tion score if one or more contaminants were present at a
concentration above the guideline ranges. A site was rated
moderate if one or more contaminants were within the
guideline ranges but none was in exceedance. Sites with
all contaminants below their guideline ranges were given a
low contamination score.
What the Data Show
Nationwide, 63 percent of sites showed low fish tissue
contamination, 15 percent had moderate contamination,
and 22 percent exhibited high contamination (Exhibit
3-38). Fish tissue contamination varied substantially from
one EPA Region to the next; for example, the percentage
of sites \vith low contamination ranged from 25 percent
(Region 1) to 83 percent (Region 4). Regions 2 and 9 had
Exhibit 3-38. Coastal fish tissue contaminants
in the contiguous U.S. by EPA Region,
1997-2000abc
Level of contamination:
Low
Moderate
High
25
38
37
Percent of estuarine sites in each category:
Region 1
Region 2
Region3
Region 4
Region 6
Region 9
Region 10
All U.S.
39
20
53
83
41
20 27
13 4
59
7 34
52 8 40
67 11
63 15
22
22
Coverage: Estuarine waters of the
contiguous 48 states.
bThis indicator is based on a
whole-body analysis of the fish. See
text for definitions of categories.
=Totals may not add to 100% due to
rounding.
Data source: U.S. EPA, 2004, 2005a
EPA Regions
the largest proportion of sites with high contamination (41
percent and 40 percent, respectively).
Data from EPA's National Coastal Database show that
nation-wide, PCBs were the contaminants most frequently
responsible for high fish tissue contamination, with 19
percent of sites above EPA guideline ranges (Exhibit 3-39).
Other chemicals present above EPA guideline ranges at
many sites were mercury in muscle tissue (18 percent of
sites), DDT (8 percent), and PAHs (3 percent) (Exhibit
3-39). Inorganic arsenic, selenium, chlordane, endosulfan,
endrin, heptachlor epoxide, hexachlorobenzene, lindane,
and mirex were below EPA guideline ranges for all fish
sampled in the NCA.
Indicator Limitations
• The indicator is limited to estuarine samples, and does not
include data from Louisiana, Florida, Puerto Rico, Alaska,
EPA's 2008 Report on the Environment
3-61
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INDICATOR
Coastal Fish Tissue Contaminants (continued)
or Hawaii, which had not been assessed at the
time this indicator was compiled. Some of
these areas (e.g., portions of Alaska) have now
been surveyed, and may be included in future
indicators.
• The data are not broken out by trophic level of
the fish and shellfish species, which influences
bioaccumulation of contaminants.
• Whole-body contaminant concentrations
in fish overestimate the risk associated with
consuming only the fillet portion of the fish,
•with the exception of mercury and cadmium,
•which are generally underestimated.
• This indicator focuses on contaminants from
a human health risk perspective. No EPA
guidance criteria exist to assess the ecological
risk of \vhole-body contaminants in fish (U.S.
EPA, 2004).
• Some fish samples used in the survey were
non-market-size juveniles, which are known
to have lower contaminant levels than larger,
market-sized fish.
• Samples are collected during an index period
from July to September, and the indicator is
only representative of this time period. It is
unlikely, however, that contaminant levels
vary substantially from season to season.
• There are no trend data for this indicator.
In EPA's second National Coastal Condition
Report, fish tissue contaminants are charac-
terized by \vhole-body concentrations and
compared to EPA risk-based consumption
guideline ranges. For the first National Coastal
Condition Report, fish contaminants -were
measured as fillet concentrations and com-
pared to U.S. Food and Drug Administration
(FDA) criteria. The data presented here -will
serve as a baseline for future surveys, however.
Data Sources
This indicator is based on an analysis published
in EPA's second National Coastal Condition
Report (U.S. EPA, 2004). Summary data by
EPA Region and by contaminant have not been
published, but -were provided by EPA's NCA
program (U.S. EPA, 2005a). Underlying sam-
pling data are housed in EPA's NCA database
(U.S. EPA, 2005b) (http://www.epa.gov/emap/
nca/html/data/index.html).
Exhibit 3-39. Coastal fish tissue contaminant
concentrations in the contiguous U.S., compared with
health-based guidelines, 1997-2000abc
Percent of estuarine sites:
Contaminant
Arsenic (inorganic)1
Cadmium
Below Within Exceeding
Guideline range guideline guideline guideline
range range range
Dieldrin
Endosulfan
Endrin
Heptachlorepoxide
Hexachlorobenzene
Lindane
Mi rex
Toxaphene
PAH (Benzo[a]pyrene)
Total PCBs
0.059-0.12
0.059-0.12
7.0-14
0.35-0.70
0.015-0.031
0.94-1.9
0.35-0.70
0.23-0.47
0.29-0.59
0.0016-0.0032
0.023-0.047
100
99
99
58
100
100
88
99
100
100
100
100
100
100
99
95
70
0
24
0
0
4
0
0
0
0
0
0
0
0
2
11
0
18
0
0
8
<1
0
0
0
0
0
0
<1
3
19
Coverage: Estuarine waters of the contiguous 48 states.
Concentrations were measured in whole fish tissue. Mercury data were adjusted to
reflect concentrations in edible fillets, where mercury accumulates (adjustment
factor of 3.0, based on the available literature). All other contaminants are
presented as whole-body concentrations.
Concentrations are compared with risk guidelines for recreational fishers for four
8-ounce meals per month (U.S. EPA, 2000,2004). Guidelines presented here are
for non-cancer risk, except for PAH, which is a cancer risk guideline.
Anorganic arsenic estimated at 2% of total arsenic.
Data source: U.S. EPA, 2005a
3-62
EPA's 2008 Report on the Environment
-------
INDICATOI
Coastal Fish Tissue Contaminants (continued)
References
Canadian Council of Ministers of the Environment. 1999.
Protocol for the derivation of Canadian tissue residue guide-
lines for the protection of wildlife that consume aquatic biota.
Prepared by the Task Force on Water Quality Guidelines.
Kannan, K., R.G. Smith, R.F. Lee, H.L. Wmdom, P.T.
Heimuller, J.M. Macauley, andJ.K. Summers. 1998. Dis-
tribution of total mercury and methyl mercury in water,
sediment and fish from South Florida estuaries. Arch.
Environ. Con. Tox. 34:109-118.
Mikac, N., M. Picer, P. Stegnar, and M. Tusek-Nidari.
1985. Mercury distribution in a polluted marine area, ratio
of total mercury, methyl mercury and selenium in sedi-
ments, mussels and fish. Water Res. 19:1387-1392.
Schmidt, C.J., and W.G. Brumbaugh. 1990. National
contaminant biomonitoring program: Concentrations of
arsenic, cadmium, copper, lead, mercury, selenium, and
zinc in U.S. freshwater fish 1976-1984. Arch. Environ.
Con. Toxicol. 19:731-747.
U.S. EPA (United States Environmental Protec-
tion Agency). 2005a. Data provided to ERG (an EPA
contractor) by Kevin Summers, EPA. September 2005.
U.S. EPA. 2005b. EMAP national coastal database.
Accessed 2005.
U.S. EPA. 2004. National coastal condition report II.
EPA/620/R-03/002.
U.S. EPA. 2000. Guidance for assessing chemical contami-
nant data for use in fish advisories. EPA/823/B-00/008.
Wmdom, H.L., and D.R. Kendall. 1979. Accumulation
and biotransformation of mercury in coastal and marine
biota. In: Nriagu, J.O., ed. Biogeochemistry of mercury in
the environment. Amsterdam, The Netherlands: Elsevier.
pp. 303-323.
taminants in Lake Fish Tissue
Lakes and reservoirs provide important sport fisheries and
other recreational opportunities, and lake ecosystems pro-
vide critical habitat for aquatic species and support wildlife
populations that depend on aquatic species for food. Lakes
and reservoirs occur in a variety of landscapes and can receive
contaminants from several sources, including direct dis-
charges into the water, atmospheric deposition, and agricul-
tural or urban runoff. A group of contaminants of particular
concern are the persistent, bioaccumulative, and toxic (PBT)
chemicals. These contaminants are highly toxic, long-lasting
chemicals that can accumulate in fish, reaching levels that can
affect the health of people and wildlife that eat them.
PBT contaminants can originate from a variety of sources.
A primary source of one of the most important PBTs,
mercury, is combustion at coal-fired power plants and other
industrial operations (see the Mercury Emissions indicator,
p. 2-46); mercury emitted to the air can then be transported
and deposited in lakes and reservoirs. Among other impor-
tant PBTs, most uses of DDT became illegal in the U.S.
effective in 1973; production of PCBs in the U.S. ceased
in 1977 and most uses were phased out by 1979 (although
they are still emitted as a byproduct of other manufacturing
processes); chlordane was banned in 1988; and quantifiable
emissions of dioxin-like compounds from all known sources
have decreased in the U.S. by an estimated 89 percent
between 1987 and 2000 (U.S. EPA, 2006a).
This indicator is based on tissue samples of predator and
bottom-dwelling fish species collected and analyzed for
EPA's National Study of Chemical Residues in Lake Fish
Tissue. The data generated from this probabilistic survey
(Olsen et al, 1998, in press; Stevens and Olsen, 2003,
2004) are designed to estimate the national distribution
of the mean levels of PBT chemicals in fish tissue from
lakes (not including the Great Lakes) and reservoirs of the
contiguous 48 states. The indicator consists of statistical
distributions of the concentrations of 15 PBT chemicals
or chemical groups in predator and bottom-dwelling fish
tissue, including mercury, arsenic (total inorganic), diox-
ins/furans, total PCBs, and 11 organochlorine pesticides.
Fourteen of these chemicals or chemical groups also appear
in the Coastal Fish Tissue indicator (p. 3-61).
Fish samples were collected from 500 lakes and reservoirs
over a 4-year period (2000-2003). Sampling locations were
selected from the estimated 147,000 target lakes and reser-
voirs in the contiguous 48 states based on an unequal prob-
ability survey design. The lakes and reservoirs were divided
into six size categories, and varying probabilities were
assigned to each category in order to achieve a similar num-
ber of lakes in each size category. The lakes and reservoirs
ranged from 1 hectare (about 2.5 acres) to 365,000 hectares
(about 900,000 acres), were at least 1 meter (3 feet) deep, and
had permanent fish populations.
EPA's 2008 Report on the Environment
3-63
-------
INDICATOR
Contaminants in Lake Fish Tissue (continued)
Exhibit 3-40. Lake fish tissue PBT contaminant
contiguous U.S., 2000-20033
Number Number
of of samples ^
Contaminant samples above MDLb
Mercury
Total PCBs
TEQdioxins/furans only
Total inorganic arsenic
Total chlordane
Total DDT
Dicofol
Dieldrin
Total endosulfan
Endrin
Heptachlor epoxide
Hexachlorobenzene
Lindane (gamma-BHC)
Mi rex
Toxaphene
486
486
486
486
486
486
486
486
486
486
486
485
486
486
486
486
486
395
2
96
378
15
24
18
3
6
0
28
10
0
0.059
0.000351
*
*
*
*
*
*
*
*
*
*
*
*
*
Coverage: Lakes and reservoirs of the contiguous 48 states. Each
bMDL = method detection
c* = less than MDL
limit; MDLs are available
concentration estimates for predators (fillets) in the
Percentiles for fillet tissue concentrations (ppm)c
10*
?dh , 50t.h . 7Rth qnth
" (median)
0.089 0.177 0.285 0.432 0.562
0.000494 0.001000 0.002161 0.008129 0.018159
* * 6x109 46x109 109x109
*****
* * * * 0.003617
*
*
*
*
*
*
*
*
*
*
sample
* 0.00147 0.00694 0.01966
* * * *
* * * *
* * * *
* * * *
* * * *
* * * *
* * * *
* * * *
reported here is a composite sample from one lake.
95th
0.833
0.033161
318x109
*
0.008266
0.03057
*
0.001193
*
*
*
*
0.000994
*
*
online at http://www.epa.gov/waterscience/fishstudy.
Data source: U.S. EPA, 2006 b
Because no predator or bottom-dwelling species occurs
in all 500 lakes and reservoirs, the study focused on 12
target predator species and six target bottom-dwelling spe-
cies in order to minimize the effect of sampling different
species. These species were chosen because they are com-
monly consumed in the study area, have a wide geographic
distribution, and potentially accumulate high concentra-
tions of PBT chemicals. Sampling teams applied consistent
materials and methods nation-wide. From each lake or
reservoir, teams collected composite samples of five adult
fish of similar size for one predator species (e.g., bass or
trout) and one bottom-dwelling species (e.g., carp or cat-
fish) (U.S. EPA, 2000). Fillets were analyzed for predators,
and whole bodies were analyzed for bottom-dwelling fish.
Fillet data represent the edible part of the fish most relevant
to human health, while whole-body data are more relevant
to wildlife consumption. A single laboratory prepared fish
tissue samples for analysis in a strictly controlled envi-
ronment, and tissue samples were sent to four analytical
laboratories. The same laboratory analyzed tissue samples
for each chemical group (e.g., PCBs or organochlorine
pesticides), using the same standard analytical method,
for the duration of the study. Concentrations of dioxins
and furans were reported on a toxic equivalency quotient
(TEQ) basis, which adjusts for the different toxicities of the
various dioxin and furan compounds.
What the Data Show
Mercury, PCBs, dioxins and furans, and DDT are
•widely distributed in lakes and reservoirs in the contigu-
ous 48 states (Exhibits 3-40 and 3-41). Mercury and
PCBs \vere detected in 100 percent of both predator and
bottom-dweller composite samples. Dioxins and furans
•were detected in 81 percent of the predator composite
samples and 99 percent of the bottom-dweller com-
posite samples, and DDT was detected in 78 percent of
the predator composites and 98 percent of the bottom-
dweller composites. One chemical analyzed in this study
(hexachlorobenzene) was not detected in any of the fish
tissue samples.
3-64
EPA's 2008 Report on the Environment
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INDICATOI
Contaminants in Lake Fish Tissue (continued)
Exhibit 3-41. Lake fish tissue PBT contaminant concentration estimates for bottom-dwellers (whole fish)
in the contiguous U.S., 2000-20033
Contaminant
Mercury
Total PCBs
TEQdioxins/furans only
Total inorganic arsenic
Total chlordane
Total DDT
Dicofol
Dieldrin
Total endosulfan
Endrin
Heptachlorepoxide
Hexachlorobenzene
Lindane (gamma-BHC) 1
Mi rex
Toxaphene
395
395
395
395
395
395
395
395
395
395
395
395
395
395
395
Number Number
of of samples
samples above MDLb
395
395
393
36
197
388
Percentiles for whole-body tissue concentrations (ppm)c
5th
0.019
0.001579
19x109
0.00108
10th
0.020
0.002308
25th
0.039
0.005146
50th
(median)
0.069
0.013876
75th
0.124
0.070050
90th
0.220
0.130787
59x109 165x109 406x109 1067x 109 1770x109
0.001653 0.009313 0.025964
0.01268 0.03535 0.15392
73
23
14
25
0
31
19
1
*
*
*
*
*
*
*
*
*
0.003436
95th
0.247
0.198324
2006x109
0.037
0.030931
0.21863
*
0.024613
*
*
*
*
*
*
*
*
*
*
*
0.000729
*
*
*
*
0.000676
*
0.001541
0.001866
*
Coverage: Lakes and reservoirs of the contiguous 48 states. Each sample reported here is a composite sample from one lake.
bMDL = method detection limit; MDLs are available online at http://www.epa.gov/waterscience/fishstudy.
=* = less than MDL
Data source: U.S. EPA, 2006b
Median concentrations in predator fillets (i.e., half of
the lakes and reservoirs had fish with higher values) were
as follows: mercury, 0.285 ppm; total PCBs, 2.161 ppb;
dioxms and furans, 0.006 ppt [TEQ]; and total DDT,
1.47 ppb (Exhibit 3-40). Median concentrations in whole,
bottom-dwelling fish were lower for mercury (0.069
ppm), but higher for total PCBs (13.88 ppb), dioxins and
furans (0.406 ppt [TEQ]), and total DDT (12.68 ppb)
(Exhibit 3-41).
Indicator Limitations
• Survey data are not available for Alaska, Hawaii, or
Puerto Rico.
• The Great Lakes, the Great Salt Lake, and lakes without
permanent fish populations are not included in the
target population.
• Because the distribution of sampling sites was based on the
frequency of occurrence of lakes and reservoirs, contami-
nants in lakes and reservoirs in arid states (e.g., Arizona,
New Mexico, and Nevada) are not -well-represented.
• Due to the inaccessibility of some target lakes (e.g., land-
owner denial of access), the results are representative of the
sampled population of lakes (approximately 80,000) rather
than the original target population of 147,000 lakes.
• The indicator does not compare contaminant data to
human health thresholds; EPA has not yet finalized that
portion of the analysis.
• Trend data are not yet available, as this is the first time
that a national lake fish tissue survey has been conducted
using a probabilistic sampling design. These data will
serve as a baseline for future surveys.
Data Sources
The data for Exhibits 3-40 and 3-41 were obtained from
EPA's National Lake Fish Tissue Study. A report on the
findings of this study was still in progress at the time this
ROE went to press; however, partial results have been
published in U.S. EPA (2006b) (http://www.epa.gov/
waterscience/fishstudy/results.htm), along with informa-
tion about how to obtain more detailed results on CD.
EPA's 2008 Report on the Environment
3-65
-------
INDICATOR
Contaminants in Lake Fish Tissue (continued)
References
Olsen, A.R., B.D. Snyder, L.L. Stahl, andJ.L. Pitt. In press.
Survey design for lakes and reservoirs in the United States to
assess contaminants in fish tissue. Environ. Monit. Assess.
Olsen, A.R., D.L. Stevens, Jr., and D. White. 1998. Appli-
cation of global grids in environmental sampling. Comp.
Sci. Stat. 30:279-284.
Stevens, D.L. Jr., and A.R. Olsen. 2004. Spatially-
balanced sampling of natural resources. J. Am. Stat. Assoc.
99(465):262-278.
Stevens, D.L. Jr., and A.R. Olsen. 2003. Variance
estimation for spatially balanced samples of environmental
resources. Environmetrics 14:593-610.
U.S. EPA (United States Environmental Protection
Agency). 2006a. Inventory of sources of environmental
releases of dioxin-like compounds in the United States:
The year 2000 update. EPA/600/P-03/002a.
U.S. EPA. 2006b. National Lake Fish Tissue Study-
results. Updated February 27, 2006.
U.S. EPA. 2000. Field sampling plan for the national study
of chemical residues in lake fish tissue. EPA/823/R-02/004.
3.8.3 Discussion
What These Indicators Say About Trends
in the Condition of Consumable Fish and
Shellfish and Their Effects on Human Health
The ROE indicators provide baseline information about
consumable fish in inland lakes, reservoirs, and coastal areas.
The data were collected from a variety of species, reflecting
many parts of the food web. The results for fish in estuarine
sites along the Atlantic, Gulf, and Pacific coasts of the con-
tiguous 48 states (Coastal Fish Tissue indicator, p. 3-61) varied
substantially among the seven coastal EPA Regions. Fish from
the coastal waters of the Southeast (EPA Region 4) generally
had low contamination scores, while several other Regions
had a substantial proportion with high contamination. PCBs,
mercury, DDT, and PAHs appeared to be the contaminants
responsible for the most high contamination scores.
The results for lake fish (Lake Fish Tissue indicator, p. 3-63)
suggest that several chemical contaminants are widely distrib-
uted in the nation's lakes and reservoirs, including mercury,
dioxins and furans, PCBs, and DDT. However, some of the
other chemicals in this screening—including certain pesti-
cides—were detected rarely or not at all. There were some
notable differences between predators and bottom-dwellers,
•which may be a result of how each type offish was analyzed—
fillets for predators and whole fish for bottom dwellers.
Limitations, Gaps, and Challenges
As explained in Section 3.8.2, both of the ROE indicators
have important limitations. For example, like the other coastal
indicators from EPA's second National Coastal Condition
Report (presented in Section 3.5), the Coastal Fish Tissue
indicator (p. 3-61) does not display trend data. It is also lim-
ited spatially, as adequate data for Alaska, Hawaii, the Carib-
bean, and the Pacific territories are not available. The lack of
data from Alaska is especially notable because more than half
of the nation's commercial fish and shellfish catch comes from
Alaskan waters.43
The Lake Fish Tissue indicator (p. 3-63) is also limited tempo-
rally and spatially, with no trend data and no coverage outside
the contiguous 48 states. Further, unlike the coastal survey, the
lake fish survey was not designed to produce results by region,
and it also does not compare contaminant levels to any health-
based guidelines. Thus, while both indicators present meaning-
ful data, the results cannot easily be compared.
The Coastal Fish Tissue and Lake Fish Tissue indicators (pp.
3-61 and 3-63) do provide some information about contami-
nation and safety offish and shellfish. However, to fully assess
the condition of the nation's fish and shellfish, more data are
needed—particularly on a national level, because many issues
have been studied locally or regionally, but have not yet been
studied in nationally representative surveys. In addition to
the limitations of the indicators described above, information
gaps for answering this question include nationally consistent
indicators of pathogens in fish and shellfish (in both fresh
•water and coastal waters) and indicators of the biological and
chemical condition offish and shellfish commercially farmed
in the U.S. There are also no ROE indicators to describe the
effects offish and shellfish condition on human health. As
noted in Chapter 1, it is often difficult to explicitly connect an
observed effect to a particular stressor (e.g., the condition of
fish and shellfish that people consume), even though there may
be scientific evidence to suggest a possible association.
National Oceanic and Atmospheric Administration. 2007. Fisheries of
the United States—2006.
3-66
EPA's 2008 Report on the Environment
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Chapter 4
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Contents
4.1 Introduction 4-3
4.1.1 Overview of the Data 4-4
4.1.2 Organization of This Chapter 4-4
4.2 What Are the Trends in Land Cover and Their Effects on Human Health
and the Environment? 4-5
4.2.1 Introduction 4-5
4.2.2 ROE Indicators 4-6
4.2.3 Discussion 4-12
4.3 What Are the Trends in Land Use and Their Effects on Human Health
and the Environment? 4-13
4.3.1 Introduction 4-13
4.3.2 ROE Indicators 4-14
4.3.3 Discussion 4-22
4.4 What Are the Trends in Wastes and Their Effects on Human Health
and the Environment? 4-23
4.4.1 Introduction 4-23
4.4.2 ROE Indicators 4-24
4.4.3 Discussion 4-28
4.5 What Are the Trends in Chemicals Used on the Land and Their Effects on
Human Health and the Environment? 4-29
4.5.1 Introduction 4-29
4.5.2 ROE Indicators 4-29
4.5.3 Discussion 4-41
4.6 What Are the Trends in Contaminated Land and Their Effects On
Human Health and the Environment? 4-42
4.6.1 Introduction 4-42
4.6.2 ROE Indicators 4-44
4.6.3 Discussion . . . 4-49
-------
4.1 Introduction
The land within the boundaries of the U.S., covering nearly
2.3 billion acres, provides food, fiber, and shelter for all
Americans, as well as terrestrial habitat for many other
species. Land is the source of most extractable resources, such
as minerals and petroleum. Land produces renewable resources
and commodities such as livestock, vegetables, fruit, grain, and
timber; it also supports other uses, such as residential, industrial,
commercial, and transportation uses. Additionally, land and the
ecosystems that it is part of provide services such as trapping
chemicals as they move through soil, storing and breaking down
chemicals and wastes, and filtering and storing water. The use
of land, what is applied to or released on it, and its condition
change constantly: there are changes in the types and amounts of
resources that are extracted, the distribution and nature of cover
types, the amounts and types of chemicals used and wastes man-
aged, and perceptions of the land's value.
Numerous agencies and individuals have responsibilities for
managing and protecting land in the U.S., in terms of resources
associated with land (e.g., timber, minerals) and land uses (e.g.,
•wilderness designations, regulatory controls). Between 30 and
40 percent of the nation is owned or managed by public agen-
cies.1 The other 60 to 70 percent is managed by private owners,
under a variety of federal, state, and local laws. Local govern-
ments have primary responsibilities for regulating land use,
•while state and federal agencies regulate chemicals and waste
that are frequently used on, stored on, or released to land. EPA
is interested in land because human activities on land such as
food and fiber production, land development, manufacturing,
or resource extraction can involve the creation, use, or release
of chemicals and pollutants that can affect the environment and
human health.
EPA \vorks \vith other federal agencies, states, and partners to
protect land resources, ecosystems, environmental processes,
and uses of land through regulation of chemicals, waste, and
pollutants, and through cleanup and restoration of contami-
nated lands. The complexities of responsibilities underscore
the challenges of collecting data and assessing trends on the
state of land.
This chapter addresses critical land questions by describing
national trends in naturally occurring and human uses of land,
stressors that affect land, and associated exposures and effects
among humans and ecological systems. ROE indicators are
presented to address five fundamental questions about the state
of the nation's land:
• What are the trends in land cover and their effects
on human health and the environment? "Land cover"
refers to the actual or physical presence of vegetation or
other materials (e.g., rock, snow, buildings) on the surface
EPA's 2008 Report on the Environment (ROE): Essentials
ROE Approach
This 2008 Report on the Environment:
• Asks questions that EPA considers im-
portant to its mission to protect human
health and the environment.
• Answers these questions, to the extent
possible, with available indicators.
• Discusses critical indicator gaps, limita-
tions, and challenges that prevent the
questions from being fully answered.
ROE Questions
The air, water, and land chapters (Chapters
2, 3, and 4) ask questions about trends in
the condition and/or extent of the envi-
ronmental medium; trends in stressors to
the medium; and resulting trends in the
effects of the contaminants in that medium
on human exposure, human health, and
the condition of ecological systems.
The human exposure and health and
ecological condition chapters (Chapters
5 and 6) ask questions about trends in
aspects of health and the environment
that are influenced by many stressors
acting through multiple media and by
factors outside EPA's mission.
ROE Indicators
An indicator is derived from actual mea-
surements of a pressure, state or ambient
condition, exposure, or human health or
ecological condition over a specified geo-
graphic domain. This excludes indicators
such as administrative, socioeconomic, and
efficiency indicators.
Indicators based on one-time studies are
included only if they were designed to serve
as baselines for future trend monitoring.
All ROE indicators passed an independent
peer review against six criteria to ensure
that they are useful; objective; transparent;
and based on data that are high-quality,
comparable, and representative across space
and time.
Most ROE indicators are reported at the
national level. Some national indicators
also report trends by region. EPA Regions
were used, where possible, for consistency
and because they play an important role in
how EPA implements its environmental
protection efforts.
Several other ROE indicators describe
trends in particular regions as examples of
how regional indicators might be included
in future versions of the ROE. They are
not intended to be representative of trends
in other regions or the entire nation.
EPA will periodically update and revise
the ROE indicators and add new indicators
as supporting data become available. In the
future, indicators will include information
about the statistical confidence of status
and trends. Updates will be posted elec-
tronically at http://www.epa.gov/roe.
Additional Information
You can find additional information about
the indicators, including the underly-
ing data, metadata, references, and peer
review, at http://www.epa.gov/roe.
Lubowski, R.N., M.Vesterby, S. Bucholtz, A. Baez, and M.J. Roberts. 2006.
Major uses of land in the United States, 2002. Economic Information Bul-
letin No. (EIB-14). U.S. Department of Agriculture, Economic Research
Service,
EPA's 2008 Report on the Environment
4-3
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of the land (it differs from land use—see the next question).
It is important from the perspective of understanding land
as a resource and its ability to support humans and other
species. Changes in land cover can affect other media (e.g.,
air and water).
• What are the trends in land use and their effects on
human health and the environment? "Land use" refers
to the economic and cultural activities practiced by humans
on land. Land use can have effects on both human health
and the environment, particularly as land is urbanized or
used for agricultural purposes.
• What are the trends in wastes and their effects on
human health and the environment? Numerous types
of waste are generated as part of most human activities.
Trends in waste include trends in types and quantities of,
and mechanisms for, managing wastes. Waste trends reflect
the efficiency of use and reuse of materials and resources
and potential for land contamination.
• What are the trends in chemicals used on the land
and their effects on human health and the environ-
ment? Various chemicals are produced or used on land for
many purposes. The quantity and diversity of chemicals
and the potential for interactions among them have created
challenges in understanding the full effects of their use.
Pesticides, fertilizers, and toxic chemicals are examples of
chemicals applied or released on land.
• What are the trends in contaminated land and their
effects on human health and the environment? Con-
taminated lands are those lands that have been affected by
human activities or natural events such as manufacturing,
mining, waste disposal, volcanoes, or floods that pose a
concern to human health or the environment. The -worst-
contaminated lands are tracked and their cleanups overseen
by EPA.
These ROE questions are posed without regard to whether
indicators are available to answer them. This chapter presents
the indicators available to answer these questions, and also
points out important gaps where nationally representative data
are lacking.
4.1.1 Overview of the Data
Data are collected by many agencies with varying responsibili-
ties for managing and protecting land and its resources. Several
different sources and types of data are used to develop the indi-
cators that address the questions in this chapter. They include:
• Satellite imagery. Data used in the land cover question
are derived from analysis of satellite data.2 A set of data on
U.S. land cover called the National Land Cover Database
is currently available for the period around 2001. Analyses
are currently underway to compare these data with earlier
land cover data, to provide a better understanding of trends.
Multiple agencies, including EPA, have jointly funded
satellite data processing efforts and are working together to
derive a common classification approach for the data.
• National surveys. The data used in the land use ques-
tion are primarily derived from two national surveys: the
National Resources Inventory (NRI)3 conducted by the
U.S. Department of Agriculture (USDA) Natural Resource
Conservation Service and the Forest Inventory and Analy-
sis (FIA)4 conducted by the USDA Forest Service. These
surveys are collected over specific areas for specific USDA
purposes; the NRI data are collected only on non-federal
lands, and FIA data address only forest and timberlands.
These limitations contribute to the need to rely on multiple
data sets for national estimates.
• Regulatory data. The data used for most of the chemical,
•waste, and contaminated land questions are derived from
self-reporting or government-collected measurements to
address regulatory requirements. For example, the chemical
release information reported under the chemical question is
derived from the Toxics Release Inventory based on indus-
try reporting. These data, in general, represent only a small
sample of the total picture of waste, chemicals, and land
contamination. State and local governments collect addi-
tional data, but the lack of consistency in approaches makes
compilation of national data difficult.
This chapter presents only data that meet the ROE indica-
tor definition and criteria (see Box 1-1, p. 1-3). Note that
non-scientific indicators, such as administrative and economic
indicators, are not included in this definition. Thorough docu-
mentation of the indicator data sources and metadata can be
found online at http://www.epa.gov/roe. All indicators were
peer-reviewed during an independent peer review process
(again, see http://www.epa.gov/roe for more information).
Readers should not infer that the ROE indicators included
reflect the complete state of knowledge on the nation's land.
Many other data sources, publications, and site-specific research
projects have contributed to the current understanding of land
trends, but are not used in this report because they did not meet
some aspect of the ROE indicator criteria.
4.1.2 Organization of This
Chapter
The remainder of this chapter is organized into five sections
corresponding to the five questions that EPA seeks to answer
about land. Each section introduces a question and its impor-
tance, presents the ROE indicators to help answer the ques-
tion, and discusses what the ROE indicators, taken together,
2 Multi-Resolution Land Characteristics Consortium. 2007. National Land
Cover Database 2001 (NLCD 2001). Accessed November 28, 2007.
3 U.S. Department of Agriculture, Natural Resources Conservation Service.
2007. National Resources Inventory, 2003 annual NRI: Land use.
Smith, WB., P.O. Miles, J.S.Vissage, and S.A. Pugh. 2004. Forest resources of
the United States, 2002. USDA Forest Service,
4-4
EPA's 2008 Report on the Environment
-------
say about the question. Several of the National Indicators
also provide information organized by EPA Regions, and
one Regional Indicator addresses specific issues at a sub-EPA
Region scale. Each section concludes by highlighting the
major challenges to answering the question and identifying
important information gaps.
Table 4-1 lists the indicators used to answer the five questions
in this chapter and shows where the indicators are presented.
4.2 What Are the Trends
Effects on Human Health
and the Environment?
4.2.1 Introduction
Land cover—the surface components of land that are physi-
cally present and visible—provides a means to examine
landscape patterns and characteristics. Patterns and landscape
characteristics are important in understanding the extent,
availability, and condition of lands; ecological system extent,
structure, and condition; and the potential for dispersion and
effects of chemicals and other pollutants in and on the envi-
ronment. Land cover represents a starting point from which
a variety of monitoring activities can be performed. EPA
considers land cover information to be critically important for
a number of reasons, including the ability to assess nonpoint
sources of pollution, understanding landscape variables for
ecological analyses, assessing the behavior of chemicals, and
analyzing the effects of air pollution.
Land cover, in its naturally occurring condition, integrates and
reflects a given site's climate, geology and soils, and available
biota over a time span of decades or longer. Land cover can be
affected on shorter time scales by naturally occurring distur-
bances (e.g., storms, floods, fires, volcanic eruptions, insects,
landslides) and human activities. Land cover represents the
results of both naturally occurring conditions and disturbances
and human activities such as population change, industrial
and urban development, deforestation or reforestation, water
diversion, and road-building. Depending on one's perspective,
the changes wrought by natural processes and human activities
can be perceived as improvements or degradations of the state
of land cover.
Table 4-1. Land—ROE Questions and Indicators
What are the trends in land cover and their
effects on human health and the environment?
What are the trends in land use and their effects
on human health and the environment?
What are the trends in wastes and their effects
on human health and the environment?
What are the trends in chemicals used on the
land and their effects on human health and
the environment?
What are the trends in contaminated land and
their effects on human health and
the environment?
Indicator Name
Section Page
Land Cover (N/R)
Forest Extent and Type (N/R)
Land Cover in the Puget Sound/Georgia Basin (R)
Land Use (N/R)
Urbanization and Population Change (N/R)
Quantity of Municipal Solid Waste Generated and
Managed (N)
Quantity of RCRA Hazardous Waste Generated
and Managed (N)
Fertilizer Applied for Agricultural Purposes (N/R)
Toxic Chemicals in Production-Related Wastes
Combusted for Energy Recovery, Released,
Treated, or Recycled (N)
Pesticide Residues in Food (N)
Reported Pesticide Incidents (N)
Current Human Exposures Under Control at
High-Priority Cleanup Sites (N)
Migration of Contaminated Ground Water Under
Control at High-Priority Cleanup Sites (N)
4.2.2 4-7
6.2.2 6-8
4.2.2 4-10
4.3.2 4-14
4.3.2 4-19
4.4.2 4-24
4.4.2 4-26
4.5.2 4-30
4.5.2 4-33
4.5.2 4-37
4.5.2 4-39
4.6.2 4-44
4.6.2 4-47
N = National Indicator
R = Regional Indicator
N/R = National Indicator displayed at EPA Regional scale
EPA's 2008 Report on the Environment
4-5
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Land cover is also important because it affects other environ-
mental variables including water quality, -watershed hydrology,
habitat and species composition, climate, and carbon storage.
Land cover influences the mass and energy exchanges between
the surface and the atmosphere and thus influences weather
and climate.5 Land cover is also a primary ingredient of eco-
logical structure and function, with changes affecting species
habitat and distribution. Land cover changes in -watersheds can
alter hydrologic regimes, runoff patterns, and flood buffering.6
4.2.2 ROE Indicators
The question of trends in and effects of land cover is addressed
by two National Indicators and one Regional Indicator (Table
4-2). Nation-wide land cover information is derived from two
data collection programs: the National Land Cover Database
(NLCD) and the Forest Inventory and Analysis (FIA). The
NLCD is described in more detail in the Land Cover indica-
tor summary (p. 4-7), and the FIA is described in the Forest
Extent and Type indicator summary (p. 6-8).
The classification approach used in the Land Cover indicator is
primarily based on the use of satellite data processing. Where
satellite data -were not available or processed, survey data have
been included to develop the national statistics. The classifica-
tion approach used in the Land Cover in Puget Sound/Geor-
gia Basin indicator (p. 4-10), -while also based on satellite data,
is different from the Land Cover National Indicator, and is
described in the Regional Indicator discussion. More detailed
definitions of land cover types are included in the box -within
the text of the Land Cover indicator (p. 4-7).
Data for the Land Cover in Puget Sound/Georgia Basin indi-
cator are derived from the NOAA Coastal Change Analy-
sis Program and Landsat satellite data of both the U.S. and
Canadian portions of the Puget Sound/Georgia Basin. This
indicator depicts two cover classes: forest and urban.
The data presented in the Forest Extent and Type indicator are
derived from national surveys of forest land and timberland
in the U.S. These data reflect total extent of forest land both
nationally and by EPA Region, as -well as trends in many spe-
cies types on timberland.
Table 4-2. ROE Indicators of Trends in Land Cover and Their
Effects on Human Health and the Environment
National Indicators
Land Cover(N/R)
Forest Extent and Type (N/R)
Regional Indicators
Land Cover in the Puget Sound/Georgia Basin
Section
4.2.2
6.2.2
Section
4.2.2
4-7
6-8
4-10
N/R = National Indicator displayed at EPA Regional scale
Marland, G., R.A. Pielke, Sr., M. Apps, R. Avissar, R.A. Belts, K.J. Davis, et al.
2003.The climatic impacts of land surface change and carbon management.
and the implications for climate-change policy. Clim. Pol. 3:149-157.
de Sherbinin,A. 2002. Land-use and land-cover change: A CIESIN thematic
guide. Palisades, NY: Center for International Earth Science Information
Network of Columbia University,
4-6
EPA's 2008 Report on the Environment
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Land Cover
Land cover represents the actual or physical presence
of vegetation (or other materials where vegetation is
nonexistent) on the land surface. Land cover is also often
described as what can be seen on land when viewed from
above. Land cover is one means to categorize landscape
patterns and characteristics, and is critical in understanding
the condition of the environment, including the availabil-
ity of habitat, changes in habitat, and dispersion and effects
of chemicals and other pollutants in and on the environ-
ment. For the purposes of this indicator, land cover is
described in terms of six major classes: forest, grass, shrub,
developed, agriculture, and other (includes ice/snow, bar-
ren areas, and wetlands). A seventh category, water, is not
discussed as a land cover type in this chapter. See Chapter
3 for more information on trends related to water. More
information about forest land can be found in the Forest
Extent and Type indicator (p. 6-8), and wetland acreage
is discussed in greater detail in the Wetlands indicator (p.
3-32).
In 1992, several federal agencies agreed to operate as a
consortium, known as the Multi-Resolution Land Char-
acteristics (MRLC) Consortium, to acquire and analyze
satellite-based remotely sensed data for environmental
monitoring programs (MRLC Consortium, 2006). The
initial result of the MRLC effort was development of the
1992 National Land Cover Dataset (NLCD), which, until
recently, was the only comprehensive recent classification
of land cover in the contiguous U.S. (USGS, 2007). In
2007, the MRLC Consortium published the 2001 National
Land Cover Database, an updated and improved version of
the 1992 NLCD (Homer et al, 2007). The database pro-
vides information about 16 land cover classes at a 30-meter
Exhibit 4-1. Land cover of the contiguous U.S., based on 2001 NLCD£
aSee box on p. 4-9 for definitions of land cover
categories.
Data source: U.S. EPA, 2007b
Agriculture Developed Forest cover
Cultivated crops • High-density (impervious £80%) • Deciduous forest
Pasture/hay • Medium-density (impervious 50-79%) • Evergreen forest
• Low-density (impervious 20-49%) i Mixed forest
• Open space (impervious <20%)
Grass cover
Grassland
Shrub cover
Shrubland
Other
D Perennial ice/snow
Barren
• Woody wetland
• Emergent herbaceous wetland
Water
• Open water
EPA's 2008 Report on the Environment
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Land Cover (continued)
Exhibit 4-2. Land cover types in the U.S., based
on 2001 NLCD and FIAabc
Agriculture
448.9 million acres
(21.9%)
Grass cover
290.5 million
acres
(14.1%)
Shrub cover
419.2 million acres
(20.4%)
Developed
102.5 million acres
(5.0%)
Otherd
117.7 million
acres
(5.7%)
Water
33.5 million
acres
(1.6%)
Coverage: All surface area of the contiguous 48 states, plus forest
land in Alaska and Hawaii.
bSee box on p. 4-9 for definitions of land cover categories.
cTotals may not add to 100% due to rounding.
d"0ther" includes ice/snow, barren areas, and wetlands.
Data source: Smith et al., 2004; U.S. EPA, 2007b
resolution, comprising approximately 27 billion cells cov-
ering the contiguous U.S., based on Landsat images from
1999 to 2002. Due to differences in methodology, direct
comparison of the 1992 and 2001 NLCD data sets does not
currently provide valid trend data. Efforts are underway to
develop an algorithm that will allow such comparisons in
the near future.
This indicator represents data from the 2001 NLCD and
the U.S. Department of Agriculture Forest Service's Forest
Inventory and Analysis (FIA), which uses a statistical survey
design and comparable methods to assess the extent, type,
age, and health of forests on private and public land in all
states. The 2001 NLCD provides a synoptic classification of
land cover, but does not include Alaska and Hawaii, thereby
classifying only 1.92 billion acres out of approximately 2.3
billion acres of land in the U.S. To supplement the NLCD,
data from the 2001 FIA were used to provide forest cover
estimates in Alaska and Hawaii (128.6 million acres).
For this indicator, the 16 land cover classes created in the
NLCD were aggregated into the six major land cover types
described above, along with water (Heinz Center, 2005).
Exhibit 4-3. Land cover types in the U.S. by
EPA Region, based on 2001 NLCD and FIAa
400
350
_ 300
CO
I 250
= 200
f 15°
E
< 100
50
HR^
—
=
=
—
-
—
—
—
-
—
~
—
=
-
m
U
n
D Other0
• Developed
D Shrub cover
D Grass cover
D Agriculture
• Forest cover
R1 R2 R3 R4 R5 R6 R7 R8 R9 R10
EPA Region
Coverage: All land area of the
contiguous 48 states (excluding
water), plus forest land in Alaska
and Hawaii.
bSee box on p. 4-9 for definitions of
land cover categories.
c"0ther" includes ice/snow, barren
areas, and wetlands.
Data source: Smith etal., 2004; U.S. EPA, 2007b
EPA Regions
What the Data Show
The combination of the NLCD for the contiguous 48
states and the FIA for forest cover estimates in Alaska and
Hawaii shows approximately 641 million acres of forest,
449 million acres of agriculture, 419 million acres of shrub,
291 million acres of grass, and 103 million acres of devel-
oped cover types (Exhibits 4-1 and 4-2).
NLCD and FIA data show variation in cover types by
EPA Region, with forest dominating in Regions 1, 2, 3, 4,
and 10; agriculture in Regions 5 and 7; grass in Region 8;
and shrub in Region 6 and 9 (Exhibit 4-3). Two-thirds of
the grass acreage in the nation is located in Regions 6 and
8, nearly two-thirds of shrub acreage is in Regions 6 and
9, and nearly half the forest acreage is in Regions 4 and 10
(including Alaska).
Indicator Limitations
Trend data are not available for this indicator. Land
cover data for the entire nation at adequate resolution
to support this indicator are currently available for two
points in time (1992 and 2001). However, due to differ-
ences in methodology in creation of the data sets, they
are not directly comparable. The MRLC Consortium
is developing a change product intended to enable valid
4-8
EPA's 2008 Report on the Environment
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INDICATOI
Land Cover (continued)
Definitions of Land Cover Categories for Exhif
Agricultural (NLCD 2001 definition): Areas charac-
terized by herbaceous vegetation that has been planted;
is intensively managed for the production of food, feed,
or fiber; or is maintained in developed settings for spe-
cific purposes. Herbaceous vegetation must account for
75 to 100 percent of the cover. Includes the "orchards/
vineyards/other" subcategory, which covers areas
planted or maintained for the production of fruits, nuts,
berries, or ornamentals. Includes two subcategories:
"pasture/hay" and "cultivated crops."
Developed (NLCD 2001 definition): Areas char-
acterized by a high percentage (30 percent or greater)
of constructed materials (e.g., asphalt, concrete, build-
ings). Includes four subcategories: "Developed, open
space" (less than 20 percent impervious surface),
"Developed, low intensity" (20-49 percent impervious
surface), "Developed, medium intensity" (50-79 percent
impervious surface), and "Developed, high intensity"
(80 percent or more impervious surface).
Shrubland (NLCD 2001 definition): Areas charac-
terized by natural or semi-natural woody vegetation
•with aerial stems, generally less than 6 meters tall, with
individuals or clumps not touching or interlocking.
Both evergreen and deciduous species of true shrubs,
young trees, and trees or shrubs that are small or stunted
because of environmental conditions are included.
Grassland (NLCD 2001 definition): Upland areas
dominated by grammanoid or herbaceous vegetation,
generally greater than 80 percent of the total vegetation.
These areas are not subject to intensive management,
such as tilling, but can be utilized for grazing.
comparisons of the two data sets (MRLC Consortium,
2007a,b). The product is scheduled to be available in
2008. Until this project is completed, there are no consis-
tent, comprehensive, nation-wide data to describe trends
in land cover at the national or EPA Regional levels.
FIA data for forest land in Alaska and Hawaii were
used to complement the NLCD because NLCD data
do not currently exist for these states, although they are
planned for late 2007. Ongoing data collection under
both the FIA and the NLCD is needed to assess land
cover trends.
National estimates of land cover vary, depending on the
survey approach, data sources, classification, timing, etc.
The interaction of these variables will result in different
estimates of the extent of any given land cover category
depending on the data set used. Techniques relying on
Forest (NLCD 2001 definition): Areas characterized
by tree cover (natural or semi-natural woody vegeta-
tion, generally greater than 6 meters tall); tree canopy
accounts for 25 to 100 percent of the cover.
Forest (FIA definition): Land at least 10 percent
stocked by forest trees of any size, including land that
formerly had such tree cover and that will be naturally
or artificially regenerated. Forest land includes transi-
tion zones, such as areas between heavily forested and
nonforested lands that are at least 10 percent stocked
•with forest trees and forest areas adjacent to urban and
built-up lands. Also included are pinyon-juniper and
chaparral areas in the West and afforested areas. The
minimum area for classification of forest land is 1 acre.
Roadside, streamside, and shelterbelt strips of trees must
have a crown width of at least 120 feet to qualify as
forest land. Unimproved roads and trails, streams, and
clearings in forest areas are classified as forest if less than
120 feet \vide. (FIA data are used in Alaska and Hawaii,
due to lack of NLCD availability.)
Other: Includes NLCD 2001 snow, ice, wetlands, and
barren. Barren areas are defined as areas of bedrock, des-
ert pavement, scarps, talus, slides, volcanic material, gla-
cial debris, sand dunes, strip mines, gravel pits, and other
accumulations of earthen material. Generally, vegetation
accounts for less than 15 percent of total cover.
Sources: U.S. EPA, 2007a; Smith et al, 2004.
satellite data to generate land cover estimates classify what
is visible from above, meaning they may underestimate
developed cover in heavily treed urban areas and underes-
timate forest cover where trees have been harvested. For
example, National Resources Inventory (USDA NRCS,
2007) estimates for developed land are 6 percent above
the NLCD estimates and FIA estimates of forestland in
2002 are nearly 17 percent above the NLCD.
No standardized land cover classification system is cur-
rently used among federal agencies. As a result of this
limitation, there is no consistency in the assessment of
land cover trends across agencies.
Data Sources
Land cover data for the contiguous 48 states were obtained
from the NLCD (U.S. EPA, 2007b). These data were
EPA's 2008 Report on the Environment
4-9
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INDICATOR
Land Cover (continued)
grouped into the major land cover categories as described
by the Heinz Center (2005) (see technical note for the
Heinz Center's "Ecosystem Extent" indicator). Forest cover
estimates for 2002 in Alaska and Hawaii were obtained
from a report published by the FIA program (Smith et al.,
2004). FIA data in this report have a nominal date of 2002
but represent the best data available at the end of the 2001
field season for each state.
References
Heinz Center (The H. John Heinz III Center for Sci-
ence, Economics, and the Environment). 2005. The state
of the nation's ecosystems: Measuring the lands, waters,
and living resources of the United States. New York, NY:
Cambridge University Press. Web update 2005:
Homer, C., J. Dewitz, J. Fry, M. Coan, N. Hossain, C.
Larson, N. Herold, A. McKerrow, J.N. VanDriel, andj.
Wickham. 2007. Completion of the 2001 National Land
Cover Database for the conterminous United States.
Photogramm. Eng. Rem. S. 73(4):337-341.
MRLC Consortium. 2007a. Comparison of NLCD 1992
and NLCD 2001. Accessed December 2007.
MRLC Consortium. 2007b. Frequently asked questions.
Accessed December 2007.
MRLC Consortium. 2006. About the MRLC program.
Accessed January 2006.
Smith, W.B., P.O. Miles, J.S. Vissage, and S.A. Pugh.
2004. Forest resources of the United States, 2002. USDA
Forest Service.
USDA NRCS (United States Department of Agriculture,
Natural Resources Conservation Service). 2007. National
Resources Inventory, 2003 annual NRI: Land use.
U.S. EPA (United States Environmental Protection
Agency). 2007a. NLCD classification schemes. Accessed
November 28, 2007.
U.S. EPA. 2007b. NLCD 2001 data provided to ERG (an
EPA contractor) by James Wickham, Office of Research
and Development. November 29, 2007.
USGS (United States Geological Survey). 2007. National
Land Cover Dataset 1992 (NLCD 1992). Accessed
November 2007.
INDICATOR
.and Cover in the Puget Sound/Georgia Basin
Changes in land use and corresponding changes in land
cover can alter the basic functioning and resilience
of ecological systems. Watersheds, for example, experi-
ence a cascade of effects among critical physical, chemical,
and biological processes when land cover changes (NWP,
1995; Thorn and Borde, 1998). For instance, removal of
vegetation can increase erosion, leading to impacts on
soil and water quality, and increases in developed land
typically result in a corresponding increase in impervi-
ous surfaces with consequences for runoff, among other
issues. While individual impacts to a landscape may appear
as small changes, the combined impacts of particular land
uses or land management practices on -watersheds can have
substantial effects on water quality, species composition,
and flooding patterns (PSAT, 2002, 2004). Such com-
bined impacts are often referred to as "cumulative effects."
As a result of their potential to broadly and substantially
influence environmental condition, land cover and use are
important factors to monitor.
This indicator compares changes in two land cover met-
rics for the Puget Sound and Georgia Basin in Washington
state and part of British Columbia, Canada. The metrics
include percent change of urban and forest land cover. Data
cover the period from 1995 to 2000 for the U.S. portion
of the basin and from 1992 to 1999 for the Canadian side
of the basin. The metrics represent the change in total
urban or forested land area divided by total land area in the
•watershed. Forest and urban land cover are two of the most
important factors affecting the condition of-watersheds
in the Puget Sound Basin (Alberti and Marzluff, 2004;
Alberti, 2005). In contrast to the nation-wide land cover
indicator, -which is based on NLCD data, this indicator
relies on data derived from four assembled USGS Landsat
scenes covering the U.S. portion of the Puget Sound Basin
4-10
EPA's 2008 Report on the Environment
-------
Land Cover in the Puget Sound/Georgia Basin (continued)
British
Columbia,
Washington
and from a combined scene covering the
Canadian land area. The land cover data for
all USGS 6th field watersheds in the basin
•were produced from NOAA Coastal Change
Analysis Program (C-CAP) data and from
Canadian Baseline Thematic Mapping
(BTM) data. The USGS Hydrologic Unit
Codes and Canadian -watershed groupings
provide topographically delineated -water-
sheds, -which are aggregated, or "nested,"
into larger sub-basin and basin units.
What the Data Show
Forest Cover
Little or no change in forest cover -was
observed in 2,068 -watersheds (76 percent) of
the 2,725 -watersheds assessed (Exhibit 4-4,
panel A). However, 279 -watersheds (10 per-
cent) saw at least 2.5 percent of their mature
forest cover converted to some other land
cover, often bare ground, immature vegeta-
tion, or industrial/urban uses. At the same
time, another group of 205 -watersheds (8
percent), generally those at higher elevations,
indicated a net increase in forest cover as
young stands or cleared areas have re-grown
into more mature forest cover classes.
Urbanization
During the same period, little or no change
in urban land cover -was observed in approx-
imately 90 percent of the 2,725 assessed
-watersheds -within the basin (Exhibit 4-4,
panel B). However, urbanization increased
across many low-elevation -watersheds and
shoreline areas, -with 158 -watersheds (6
percent) expanding the urban portion of the
-watershed by bet-ween 0.7 and 1.93 per-
cent, and another 58 -watersheds (2 percent)
showing increases of more than 1.93 percent.
Research has shown that as a -watershed's
drainage area becomes paved or otherwise
impervious, there is a high potential for
physical, chemical, and biological impair-
ments to both -water quality conditions and
other aquatic resources (NWP, 1995; Alberti
and Marzluff, 2004).
Indicator Limitations
• While the U.S. C-CAP data and the Canadian BTM data
have similar and overlapping time periods, as currently
presented, the U.S. data reflect change from 1995 to 2000
and the Canadian data reflect change from 1992 to 1999.
Exhibit 4-4. Land cover change in watersheds of the
Puget Sound/Georgia Basin, 1992-2000ab
A. Forest cover
B. Urbanization
Percent change in forest cover:
• -5.0% or more n No change
• -4.9% to-2.5% 0.1% to 0.85%
-2.4% to -0.1 % More than 0.85%
British
Columbi
Washington
Percent change in urbanization:
n No change 0.301 % to 0.70%
0.05% or less • 0.71% to 1.93%
0.051 % to 0.30% • More than 1.93%
£,JUU
-g 2,000
CD
CO
& 1,500
ro
o
1 nnn
i— 1 ,UUU
.a
;! 500
n
2
147 132 173
^^H
,Ub!
j
96 109
.
Percent change
Percent change
Coverage: 2,725 watersheds within the Puget Sound/Georgia Basin, located in the
state of Washington and the Canadian province of British Columbia. U.S. watersheds
are 12-digit Hydrologic Unit Code (HUC12) watersheds.
bU.S. data reflect changes from 1995 to 2000, while Canadian data reflect changes from
1992to1999.
Data source: British Columbia Integrated Land Management Bureau, 2001; CommEn
Space, 2005; NOAA, 2006
The size of the data pixels and the minimum mapping
unit size affect the classification of certain features such
as narrow riparian corridors, and can affect the percent-
ages in the indicators.
EPA's 2008 Report on the Environment
4-11
-------
INDICATOR
Land Cover in the Puget Sound/Georgia Basin (continued)
Data Sources
The full analysis has not been published as a data set,
but it is based on publicly available data sets compiled by
CommEn Space (http://www.commenspace.org). Raw
data for the U.S. portion of this indicator are available
from C-CAP (NOAA, 2006), and Canadian data are
available from the British Columbia Integrated Land
Management Bureau (2001). Additional technical back-
ground is provided by U.S. EPA (2006).
References
Alberti, M. 2005. The effects of urban patterns on
ecosystem function. Int. Regional Sci. Rev. 28(2):168-192.
Alberti, M., andj. Marzluff. 2004. Resilience in urban
ecosystems: Linking urban patterns to human and ecological
functions. Urb. Ecosyst. 7:241-265.
British Columbia Integrated Land Management Bureau.
2001. Baseline thematic mapping,
CommEn Space. 2005. Cartography services provided
to EPA.
NOAA (National Oceanic and Atmospheric Administra-
tion). 2006. Coastal Change Analysis Program (C-CAP)
database. Accessed 2007.
NWP (Northwest Forest Plan). 1995. Ecosystem analysis at
the -watershed scale: Federal guide for -watershed analysis.
Portland, OR: USFS Regional Ecosystem Office.
PSAT (Puget Sound Action Team). 2004. State of the Sound.
Report to the Washington state legislature. Olympia, WA.
PSAT. 2002. Puget Sound update. Eighth report of the
Puget Sound ambient monitoring program. Olympia, WA.
Thorn, R., and A. Borde. 1998. Human intervention in
Pacific North-west coastal ecosystems. In: McMurray, G.R.,
and RJ. Bailey, eds. Change in Pacific North-west coastal
ecosystems. NOAA Coastal Ocean Program Decision
Analysis Series No. 11.
U.S. EPA (United States Environmental Protection
Agency). 2006. Puget Sound Georgia Basin ecosystem
indicators: Ecosystem indicator references and technical
background.
*
4.2.3 Discussion
What These Indicators Say About Trends
in Land Cover and Their Effects on Human
Health and the Environment
The most recently available 2001 data are presented for the
Land Cover indicator (p. 4-7). As of the -writing of the ROE,
the data are available for two points in time, 1992 and 2001,
but cannot be compared. Work is ongoing to develop a com-
parison database. The data show that the largest extent of a
cover type nation-wide is forest land, followed by agriculture,
shrubland, grassland, and developed land.
The Land Cover in Puget Sound/Georgia Basin indica-
tor (p. 4-10) shows that land cover in the majority of the
approximately 2,700 sub-watersheds that constitute the Puget
Sound and Georgia Basin did not change appreciably dur-
ing the time periods covered by the indicator. The data in
this Regional Indicator allow for discrimination of patterns
of-watersheds -where land cover has changed even in the
relatively short interval of 5 years. For example, forest cover
tended to decrease in coastal and mid-elevation -watersheds,
•while showing a net increase at higher elevations. Developed
U.S. Environmental Protection Agency. 2005. Estimating and projecting
impervious cover in the southeastern United States. EPA/600/R-05/061.
Athens, GA.
land cover increased somewhat in approximately 8 percent
of the sub-watersheds, mainly in -watersheds at low eleva-
tions and along the shore. These and related trends may have
consequences for human health and ecologic conditions in the
areas -where land cover is changing. For example, increases
in developed land cover may be associated -with increases in
impervious surface area, -which can cause changes in surface
•water runoff quantity and quality to the point -where detri-
mental effects on aquatic resources may occur.7
The Forest Extent and Type indicator (p. 6-8) provides trend
data for forest land cover, and shows that the total amount of
forest land in the U.S. has remained relatively constant over
recent years. On a regional basis, however, there have been
shifts, including increases in forest cover over the last century
in EPA Regions 1, 2, 3, and 5 and decreases in Regions 6 and
9. The species composition of forest cover has also shifted.8
Limitations, Gaps, and Challenges
The current lack of trend data is a key limitation of the Land
Cover indicator (p. 4-7) as -well as a gap in the data. The
changing availability of technology since the 1970s, such as
satellites and computing capacity to process large volumes of
data, has provided new tools in the effort to track trends in
3 These changes and their effects on the environment are described in Chapter 6.
4-12
EPA's 2008 Report on the Environment
-------
land cover. The use of these tools continues to be constrained
due to complexities in land cover and costs of processing. This
is one reason that trend data for national land cover using
satellite data are not currently available.
Another gap is the lack of indicators for human health effects
related to trends in land cover. While land cover extent may
represent a measure of ambient conditions and is a critical
input to many other analyses (e.g., models of the water cycle,
carbon cycle, ecological system function), it provides limited
insight in answering the question of effects on human health.
There are several challenges related to addressing the ques-
tion of trends in land cover. Two critical challenges are (1) that
land cover characteristics can vary depending on the scale of
mapping or measurement and (2) that the classification systems
used to describe land cover vary by agency and by the agen-
cies' needs. The variability of species and structure within land
cover types can be important in how land cover is affected by
pollutants or the type of habitat that is provided. While map-
ping or measuring the details of species and structure of forest
or shrubland is possible on a local basis, it is very difficult to do
consistently on a national scale. There are many different types
or categories of land cover that can be defined at very different
levels of detail, and different classification schema often make
comparability among data sets and across time frames difficult.
The major sources of data used to track land cover are based
on national surveys using unique classifications that have been
maintained over time to allow valid comparisons of important
characteristics to be made. At the same time, technology is
changing what can be measured, mapped, and classified. Data
that can be collected from ground surveys or in some cases
inferred from aerial photos—such as understory species—are
seen differently in automated satellite data processing. Coordi-
nating, integrating, and using data collected at a variety of scales
and based on diverse data sources and classifications are chal-
lenges in tracking trends in and effects of land cover.
4.3 What Are the Trends
in Land Use and Their
Effects on Human Health
and the Environment?
4.3.1 Introduction
Land use represents the economic and cultural activities
that are practiced at a place, such as agricultural, residential,
industrial, mining, and recreational uses. Land use changes
occur constantly and at many scales, and can have specific and
cumulative effects on air and water quality, -watershed func-
tion, generation of waste, extent and quality of wildlife habitat,
climate, and human health. Land use differs from land cover in
that some uses are not always physically obvious (e.g., land used
for producing timber but not harvested for many years or land
used for grazing but -without animals -will not be visible). Public
and private lands frequently represent very different uses. Urban
development seldom occurs on public lands, while private lands
are infrequently protected for -wilderness uses.
EPA is concerned about the use of land because of the potential
effects of land use and its byproducts on the environment. For
example, land development creates impervious surfaces through
construction of roads, parking lots, and other structures. Imper-
vious surfaces contribute to nonpoint source -water pollution by
limiting the capacity of soils to filter runoff. Impervious surface
areas also affect peak flow and -water volume, -which heighten
erosion potential and affect habitat and -water quality. Increased
storm -water runoff from impervious surfaces can deliver more
pollutants to -water bodies that residents may rely on for drink-
ing and recreation.9 Storm runoff from urban and suburban
areas contains dirt, oils from road surfaces, nutrients from fertil-
izers, and various toxic compounds. Point source discharges
from industrial and municipal -waste-water treatment facilities
can contribute toxic compounds and heated -water. Impervious
surfaces also affect ground -water aquifer recharge.
Some land development patterns, in particular dispersed growth
such as "suburbanization," can contribute to a variety of envi-
ronmental concerns. For example, increased air pollution due
to increased vehicle use can result in increased concentrations
of certain air pollutants in developed areas that may exacerbate
human health problems such as asthma.10 Another potential effect
of land development is the formation of "heat islands," or domes
of-warmer air over urban and suburban areas, caused by the loss
of trees and shrubs and the absorption of more heat by pave-
ment, buildings, and other sources. Heat islands can affect local,
regional, and global climate, as well as air quality.11
Agricultural land uses can affect the quality of-water and
•watersheds. The types of crops planted, tillage practices, and
various irrigation practices can limit the amount of-water
available for other uses. Livestock grazing in riparian zones
can change landscape conditions by reducing stream bank
vegetation and increasing -water temperatures, sedimentation,
and nutrient levels. Runoff from pesticides, fertilizers, and
nutrients from animal manure can also degrade -water quality.
Additionally, agricultural land uses may result in loss of native
habitats or increased -wind erosion and dust, exposing humans
to particulate matter and various chemicals.12
Some land uses can accelerate or exacerbate the spread of inva-
sive species. Certain land use practices, such as overgrazing, land
conversion, fertilization, and the use of agricultural chemicals,
U.S. Environmental Protection Agency. 2005. Estimating and projecting
impervious cover in the southeastern United States. EPA/600/R-05/061.
Athens, GA.
Schwartz J. 2004. Air pollution and children's health. Pediatrics
113:1037-1043.
U.S. Environmental Protection Agency. 2003. Cooling summertime tempera-
tures: Strategies to reduce urban heat islands. EPA/430/F-03/014.Washington.
DC.
Schenker, M. 2000. Exposures and health effects from inorganic agricultural
dusts. Environ. Health Persp. 108(Suppl 4):661-664.
EPA's 2008 Report on the Environment
4-13
-------
can enhance the growth of invasive plants.13 These plants can
alter fish and wildlife habitat, contribute to decreases in biodi-
versity, and create health risks to livestock and humans. Intro-
duction of invasive species on agricultural lands can reduce water
quality and water availability for native fish and wildlife species.
Research is beginning to elucidate the connections between
land use changes and infectious disease. For example, fragmen-
tation of forest habitat into smaller patches separated by agricul-
tural activities or developed land increases the "edge effect" and
promotes the interaction among pathogens, vectors, and hosts.14
In some cases, changes in land use may have positive effects, such
as increasing habitat as a result of deliberate habitat restoration
measures; and reclamation of lands for urban/suburban develop-
ment as a result of cleanup of previously contaminated land.
4.3.2 ROE Indicators
The question of trends in land use is addressed by two ROE
indicators: Land Use and Urbanization and Population Change
(Table 4-3). The primary information sources for these indica-
tors are the National Resources Inventory prepared by the U.S.
Department of Agriculture's Natural Resources Conservation
Service, the Forest Inventory and Analysis conducted by the
Forest Service, the Census of Agriculture from the National
Agricultural Statistics Service, and population data collected
by the U.S. Census Bureau. The box on pages 4-16 and 4-17
provides definitions of the categories used in the indicators.
Table 4-3. ROE Indicators of Trends in Land Use and Their
Effects on Human Health and the Environment
National Indicators
Land Use (N/R)
Urbanization and Population Change (N/R)
Section
4.3.2
4.3.2
4-14
4-19
N/R = National Indicator displayed at EPA Regional scale
and Use
Land use is the purpose of human activity on the land.
Unlike land cover, land use may not always be vis-
ible. For example, a unit of land designated for use as
timberland may appear identical to an adjacent unit of
protected forestland or, if recently harvested, may appear
not to be in forest land cover at all. Land use is generally
designated through zoning or regulation and is one of the
most obvious effects of human inhabitation of the planet.
It can affect both human health and ecological systems,
for example by changing the hydrologic characteristics of
a -watershed, the potential of land to erode, the condition
or contiguity of plant and animal habitat, or the spread of
vector-borne diseases.
This indicator tracks trends in acreages of major land uses
over the 1977-2003 period using several data sources. These
sources do not always cover the same time period, sample the
same resource or geography, or use the same definitions, but
each of them provides an important piece of the land use pic-
ture over time. Definitions for the various land use categories
in this indicator can be found on page 4-16.
The National Resources Inventory (NRI) conducted
by the U.S. Department of Agriculture (USDA) Natural
Resources Conservation Service was used to track trends
in "crop and pasture" land (raw crop, orchard, and pasture
uses) and "developed" land (residential, commercial, indus-
trial, and transportation uses). The NRI developed esti-
mates every 5 years on non-federal lands in the contiguous
U.S. between 1977 and 1997, and annual estimates based
on a smaller sample size beginning in 2001.
The Forest Inventory and Analysis (FIA) surveys con-
ducted by the USDA Forest Service were used to track
trends in forest and timberlands. The FIA surveys include
both private and public land in all 50 states. The FIA previ-
ously assessed forest and timberland acreage every 10 years,
but the data are now updated on a rolling basis using surveys
that sample a different portion of FIA sites every year.
The USDA National Agricultural Statistics Service
(NASS) Census of Agriculture was used to track trends in
the extent of cropland, cropland used only for pasture, pas-
tureland, and rangeland. NASS data are available for 1997
and 2002 only. Data on the extent of grass and forested
rangeland (typically "unimproved" grazing land) are avail-
able from the USDA Economic Research Service (ERS)
for 5-year intervals from 1982 through 2002.
4-14
13 Westbrooks, R.G. 1998. Invasive plants: Changing the landscape of America:
Fact book.Washington, DC: Federal Interagency Committee for the Manage-
ment of Noxious and Exotic Weeds.
EPA's 2008 Report on the Environment
Patz, J.A., P. Daszak, G.M.Tabor, A.A. Aguirre, M. Pearl, J. Epstein, N.D.Wolfe,
A.M. Kilpatrick, J. Foufopoulos, D. Molyneux, D.J. Bradley, and Members
of the Working Group on Land Use Change and Disease Emergence. 2004.
Unhealthy landscapes: Policy recommendations on land use change and infec-
tious disease emergence. Environ. Health Persp. 112(10):1092-1098.
-------
Land Use (continued)
Exhibit 4-5. Land use trends in the U.S., 1977-20033
800
700
600
500
400
300
200
100
0
NRI D Pasture
D Cropland
131.1
419.9
125.2
381.3
119.5
376.4
1170
367.9
NASS D Cropland pasture
D Cropland
66 4
378.9
60 6
373.6
NASS D Pastureland and rangeland
398.2
395.3
1977 1982 1987 1992 1997 2003 1977 1982 1987 1992 1997 2002 1977 1982 1987 1992 1997 2002
ERS :
:
] Forested grazing land
] Grassland pasture and range
158
597
155
591
145
591
141
580
134
587
FIA D Timberland
492.4
486.3
503.7
503.5
NRI D Developed
I 72.9 1| 79.5 1| 86.5 1| 98. 3 108.1
800
700
600
500
400
300
200
100
° 1977 1982 1987 1992 1997 2002 1977 1982 1987 1992 1997 2002 1977 1982 1987 1992 1997 2003
Year
aSee box on p. 4-16 for definitions of land use categories.
Data source: Lubowski et al., 2006; Smith et al., 2004; USDA NASS, 2004; USDA NRCS, 2007
What the Data Show
The acreage of lands used for growing food and forage crops
has declined since 1982, while developed land has increased
and timberland has remained approximately constant
(Exhibit 4-5). As of 2002-2003, estimates from both the
NRI (2003 data) and the NASS (2002 data) indicate that
between 368 and 374 million acres were used for food crop
production, approximately 16 percent of the U.S. land area.
Estimates of pasture or land used to support forage for live-
stock vary, depending on the definitions. The NRI classifies
117 million acres as pasture, while the NASS classifies about
61 million acres as cropland used for pasture. The NASS
classifies more than 395 million additional acres as pasture
or rangeland for grazing. The broader ERS estimate of land
available for grazing totals about 587 million acres, and
includes grassland and other non-forested pasture and range.
If forest lands used for grazing are also included, the total
ERS estimate for these lands is 721 million acres for 2002.
The NASS cropland shows a decrease in the extent of crop-
land (5 million acres), cropland pasture (6 million acres), and
pastureland and rangeland (3 million acres) between 1997
and 2002. The NRI data suggest that these declines are part
of a longer trend, with NRI cropland and pasture declining
by slightly more than 66 million acres (12 percent) between
1982 and 2003. ERS data also show a downward trend for
pasture and rangeland between 1982 and 2002, with the
largest decrease being a 24-million-acre (15 percent) decline
in forest land used for grazing. According to the NRI, 5
percent (108.1 million acres) of U.S. land area was consid-
ered developed15 as of 2003 (Exhibit 4-5). This represents
a gain of 48 percent (35.2 million acres) since 1982. While
the amount of developed land is a small fraction of the total,
its ecological impact can be disproportionately high relative
to other land use types. Paving and the creation of other
impervious surfaces can change local hydrology, climate,
and carbon cycling, leading to increased surface runoff, pol-
lution, and degradation of wetlands and riparian zones.
The land use classification for developed land uses NRI data and is
considerably different from the land cover classification for developed land,
which uses NLCD data. See Section 4.2 for more information.
EPA's 2008 Report on the Environment
4-15
-------
INDICATOR
Land Use (continued)
Definitions of Land Use Categories for Exhibits 4-5, 4-6, and 4-7
NRI (USDA NRCS, 2004)
Developed: A combination of land cover/use categories:
urban and built-up areas and rural transportation land.
Urban and built-up areas. A land cover/use category
consisting of residential, industrial, commercial, and
institutional land; construction sites; public adminis-
trative sites; railroad yards; cemeteries; airports; golf
courses; sanitary landfills; sewage treatment plants; water
control structures and spillways; other land used for such
purposes; small parks (less than 10 acres) within urban
and built-up areas; and high-ways, railroads, and other
transportation facilities if they are surrounded by urban
areas. Also included are tracts of less than 10 acres that
do not meet the above definition but are completely sur-
rounded by urban and built-up land. Two size categories
are recognized in the NRI: areas of 0.25 acre to 10 acres,
and areas of at least 10 acres.
Large urban and built-up areas. A land
cover/use category composed of developed tracts of
at least 10 acres—meeting the definition of urban
and built-up areas.
Small built-up areas. A land cover/use category
consisting of developed land units of 0.25 to 10
acres, which meet the definition of urban and
built-up areas.
Rural transportation land. A land cover/use cat-
egory \vhich consists of all high-ways, roads, railroads
and associated right-of-ways outside urban and built-
up areas; also includes private roads to farmsteads or
ranch headquarters, logging roads, and other private
roads (field lanes are not included).
Cropland: A land cover/use category that includes areas
used for the production of adapted crops for harvest. Two
subcategories of cropland are recognized: cultivated and
noncultivated. Cultivated cropland comprises land in
row crops or close-grown crops and also other cultivated
cropland, for example, hay land or pastureland that is in
a rotation -with row or close-grown crops. Noncultivated
cropland includes permanent hay land and horticultural
cropland.
Pastureland: A land cover/use category of land man-
aged primarily for the production of introduced forage
plants for livestock grazing. Pastureland cover may con-
sist of a single species in a pure stand, a grass mixture, or
a grass-legume mixture. Management usually consists of
cultural treatments: fertilization, -weed control, reseed-
ing or renovation, and control of grazing. For the NRI,
pastureland includes land that has a vegetative cover of
grasses, legumes, and/or forbs, regardless of-whether or
not it is being grazed by livestock.
FIA (Smith etal., 2004)
Forest land: Land at least 10 percent stocked by forest
trees of any size, including land that formerly had such
tree cover and that -will be naturally or artificially regen-
erated. Forest land includes transition zones, such as areas
between heavily forested and nonforested lands that are
at least 10 percent stocked -with forest trees and forest
areas adjacent to urban and built-up lands. Also included
are pinyon-juniper and chaparral areas in the West and
afforested areas. The minimum area for classification of
forest land is 1 acre. Roadside, streamside, and shelter-
belt strips of trees must have a crown -width of at least
120 feet to qualify as forest land. Unimproved roads and
trails, streams, and clearings in forest areas are classified
as forest if less than 120 feet -wide.
Timberland: Forest land that is producing or can pro-
duce crops of industrial -wood and is not withdrawn from
timber utilization by statute or administrative regulation.
(Areas qualifying as timberland must be able to produce
more than 20 cubic feet per acre per year of industrial
•wood in natural stands. Currently inaccessible and inop-
erable areas are included.)
MASS (USDA NASS, 2004)
Cropland: A category including cropland harvested,
cropland idle or used for cover crops or soil improve-
ment but not harvested and not pastured, cropland
on -which all crops failed, and cropland in cultivated
summer fallow. Not included is cropland used only for
pasture or grazing.
Cropland pasture: Cropland used only for pasture or
grazing, -which could have been used for crops -without
additional improvement. Also included are acres of crops
hogged or grazed but not harvested prior to grazing.
However, cropland pastured before or after crops -were
harvested counts as harvested cropland rather than crop-
land for pasture or grazing.
Pastureland and rangeland: All grazable land—
irrigated or dry—that does not qualify as cropland or
•woodland pasture. In some areas, this is high-quality
pastureland but cannot be cropped -without improve-
ments. In others, it can barely be grazed and is only mar-
ginally better than -waste land.
4-16
EPA's 2008 Report on the Environment
-------
Land Use (continued)
ERS (Lubowski et al., 2006)
Grassland pasture and range: All open land used
primarily for pasture and grazing, including shrub and
brush land types of pasture; grazing land with sagebrush
and scattered mesquite; and all tame and native grasses,
legumes, and other forage used for pasture or graz-
ing. Because of the diversity in vegetative composition,
grassland pasture and range are not always clearly distin-
guishable from other types of pasture and range. At one
extreme, permanent grassland may merge with cropland
pasture; grassland is also often found in transitional areas
•with forested grazing land.
Forested land grazed: Forested grazing land consists
mainly of forest, brush-grown pasture, arid woodlands,
and other areas within forested areas that have grass or
other forage growth. The total acreage of forested graz-
ing land includes woodland pasture in farms plus esti-
mates of forested grazing land not in farms. For many
states, the estimates include significant areas grazed only
lightly or sporadically. The Census of Agriculture, the
National Resources Inventory, and the Forest Inventory
and Analysis are the principal sources of data.
Forest lands are managed by a complex array of interests
to meet multiple purposes, including providing habitat
for a variety of species, recreation, and timber produc-
tion. While forest is a land cover classification, timberland
is a land use classification that reflects forest land capable of
producing at least 20 cubic feet per acre per year of indus-
trial wood and not withdrawn from timber utilization by
statute or regulation. Approximately 504 million acres of
U.S. forest land, or 22 percent of the total U.S. land area,
qualified as timberland in 2002 (Exhibit 4-5). This total
reflects a net gain of about 11 million acres (2 percent)
between 1977 and 2002, which the FIA attributes largely
to reversion of abandoned lands and reclassification of some
National Forest lands to align with clas-
sifications used on other land ownerships
(Smith etal, 2004).
Land use varies widely by EPA Region
(Exhibit 4-6). According to the most
recent data for each land use type,
Regions 6, 8, and 9 together have more
than three-quarters of the nation's graz-
ing land, while Region 4 has the largest
portion of timberland (27 percent of total
U.S. timberland). Trends also vary widely
among regions. About 83 percent of the
cropland lost between 1987 and 2003 was
in five EPA Regions (Regions 4, 5, 6, 7,
and 8) (Exhibit 4-7, panel A). Increases in
developed land are responsible for part of
this decline; for example, developed land
increased by nearly 60 percent from 1987
to 2003 in Region 4 (Exhibit 4-7, panel
B). Other factors include the federal Con-
servation Reserve Program, which has
assisted private landowners in converting
about 35 million acres of highly erod-
able cropland to vegetative cover since
1985 (as of 2004) (USDA Farm Service
Agency, 2004).
Indicator Limitations
Estimates are derived from a variety of inventories and
samples, conducted over different time periods and for
different purposes. This limits the ability to integrate
the data and track changes over time.
The NRI does not report land use data for Alaska, which
encompasses 365 million acres of the 2.3 billion acres
nation-wide. The NRI also does not provide data on
federal lands (representing 20 percent of the contiguous
U.S. land and one-third of Alaska). Because federal land
is seldom used for agriculture or urban development, and
there is relatively little developed or agricultural land in
Exhibit 4-6. Land use in the U.S. by EPA Region, 2002-20033
250
200
150
100
50
FIA
Timberland
(2002)
NASS
Cropland
(2002)
ERS
Rangeland
(2002)
NRI
Developed
(2003)
R1
R2 R3
R4
R5 R6 R7
EPA Region
R9 R10
'See box on p. 4-16 for definitions of land use categories.
Data source: Lubowski et al., 2006; Smith et al., 2004;
USDA NASS, 2004; USDA NRCS, 2007
EPA Regions
EPA's 2008 Report on the Environment
4-17
-------
Land Use (continued)
Exhibi
10
_ 8
CO
S 6
ro
= 4
o
E. 2
re 0
E
re _2
Datas
t 4-7. Changes in land use in the U.S. by EPA Region, 1977-20033
A. Acreage change
NRI developed
(1987-2003)
jJllLik
NRI crop MASS crop
& pasture & pasture
(1987-2003) (1997-2002)
'•I
— 'I1!
(1977-1987)
|
FIATimberland
(1987-1997)
1
(1997-2001)
| u
B. Percent change
NRI developed
(1987-2003)
111
NRI crop
& pasture
(1987-2003)
inr ••
MASS crop
& pasture
(1997-2002)
|-H -
(1977-1987)
FIATimberland
(1987-1997)
(1997-2001)
• ~"
-------
INDICATOI
Land Use (continued)
Land use designations are most frequently managed and
monitored by local governments, each using different
approaches and classifications. This makes national
summaries difficult.
The extent of lands used for energy production, resource
extraction, or mining is not known and represents a
data gap.
Lands specifically protected for certain uses such as -wil-
derness or parks have been periodically inventoried for
the nation. These statistics are currently not reported in
a form that allows comparison with other statistics.
Data Sources
Data were obtained from several original sources and
compiled by EPA Region. ERS data were obtained from
Lubowski et al. (2006). FIA data were obtained from Smith
et al. (2004). NASS data were published by the USDA
National Agricultural Statistics Service (2004).
References
Lubowski, R.N., M. Vesterby, S. Bucholtz, A. Baez, and
MJ. Roberts. 2006. Major uses of land in the United States,
2002. Economic Information Bulletin No. (EIB-14). U.S.
Department of Agriculture, Economic Research Service.
Smith, W.B., P.O. Miles, J.S. Vissage, and S.A. Pugh. 2004.
Forest resources of the United States, 2002. USDA Forest
Service,
USDA Farm Service Agency (United States Department of
Agriculture, Farm Service Agency). 2004. The Conservation
Reserve Program: Summary and enrollment statistics, 2004.
USDA NASS (United States Department of Agriculture,
National Agricultural Statistics Service). 2004. 2002 census
of agriculture, United States summary and state data.
Report AC-02-A-51. (QA/QC);
USDA NRCS (United States Department of Agriculture,
Natural Resources Conservation Service). 2007. National
Resources Inventory, 2003 annual NRI: Land use.
USDA NRCS. 2004. National resources inventory: 2002
annual NRI.
*
INDICATOI
Urbanization and Population Change
The total number of people and their distribution on the
landscape can affect the condition of the environment
in many ways. Increasing population often means increased
urbanization, including conversion of forest, farm, and other
lands for housing, transportation, and commercial purposes.
In recent years, many communities in the U.S. have seen
an increase in developed land (residential, commercial,
industrial, and transportation uses) that outpaces popula-
tion growth. This pattern is of concern for numerous health
and environmental reasons (Frumkin et al., 2004). For
example, studies indicate that when land consumption rates
exceed the rate of population growth, per capita air pollut-
ant emissions from driving tend to be higher. Urbanization
and population growth also tend to increase the amount of
impervious surfaces and the quantity and types of products
that humans produce, use, and discard, thereby affect-
ing waste generation and management, water quality, and
chemical production and use.
The information presented in this indicator is based on
population data collected and analyzed on a decadal basis by
the U.S. Census Bureau—as well as annual "intercensal" pop-
ulation estimates—and data collected by the U.S. Department
of Agriculture Natural Resources Conservation Service's
Exhibit 4-8. Population and urbanization in the
U.S., 1790-20003
n Rural population
n Urban population
300
250
CO
.1 20°
I150
_ro
I-100
1800 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000
Year
Coverage: 50 states and the District of Columbia.
Data source: U.S. Census Bureau, 1993, 2004
EPA's 2008 Report on the Environment
4-19
-------
Urbanization and Population Change (continued)
Exhibit 4-9. Percent change in population
and developed land in the contiguous U.S.
and Hawaii, 1982-2002ab
14
12
OJ 10
O)
c
£ 8
o
"^ £
CD D
O
O
o. 4
2
0
1982-
1987
1987-
1992
1992-
1997
1997-
2002b
Reporting period
Change in population
Change in acreage
of developed land
Coverage: Contiguous 48 states
(excluding the District of Columbia)
and Hawaii.
bBased on changes in the NRI
inventory approach, Hawaii was not sampled in 2002. Thus, the
percent change in developed land from 1997 to 2002 is based on
the 48 contiguous states only.
Data source: U.S. Census Bureau, 1996,2002b, 2006; USDA
NRCS, 2000, 2004
National Resources Inventory (NRI) to track "developed"
land. Between 1977 and 1997, the NRI developed estimates
every 5 years on non-federal lands in the contiguous U.S.
Since 2001 the NRI has developed annual estimates, but based
on a smaller sample size. This indicator captures trends in
overall population growth for both rural and urban popula-
tions; the amount of developed land relative to the amount of
population change, nationally and by EPA Region; and overall
population density, also nationally and by EPA Region.
What the Data Show
The U.S. population grew from a little over 4 million people
in 1790 to over 281 million in 2000; urban population is esti-
mated to have grown a thousandfold over that period (Exhibit
4-8). The population nearly doubled between 1950 and 2000.
The rates of population and developed land growth over
5-year intervals increased between 1982 and 1997, before
declining slightly between 1997 and 2002. Over all four
5-year increments, the amount of developed land increased
at nearly twice the rate of the population (Exhibit 4-9).
Between 1982 and 2003, the amount of developed land
in the U.S. in the 48 contiguous states (not including the
District of Columbia) grew by more than 35 million acres,
representing a cumulative increase of more than 48 percent.
Exhibit 4-10. Percent change in population and
developed land in the contiguous U.S. by EPA
Region, 1982-20033
90
80
70
O
g> 60
| 50
g 40
o
£ 30
20
10
Change in population
Change in acreage
of developed land
R1 R2 R3 R4 R5 R6 R7
EPA Region
Coverage: Contiguous 48 states
(excluding the District of Columbia).
Data source: U.S. Census Bureau,
1996, 2002b, 2006; USDA NRCS,
2000, 2007
R9 R10 All
U.S.
EPA Regions
0°
©o
The Census Bureau estimates that during the same period,
the population of the 48 states grew by nearly 58 million
people, or just over 25 percent (Exhibit 4-10).
There are substantial variations in population and devel-
opment trends in different parts of the U.S. (Exhibit 4-10).
Between 1982 and 2003, the growth rates for developed
land were higher than population growth rates in every
region except Region 8. The largest rate of increase in
population between 1982 and 2003 occurred in Region 9,
•where population increased by more than 46 percent (nearly
14 million people). Developed land in Region 9 increased
by 51 percent (more than 2.8 million acres). Region 4 had
the largest rate of increase in developed land (nearly 80 per-
cent) and the largest absolute increases in both population
(15.4 million) and developed land (11.8 million acres).
Although growth rates of population and developed
land were high in most Regions, population density varies
significantly from one Region to the next (Exhibit 4-11).
In 2005, EPA Region 2 was the most densely populated
Region, at 512 people per square mile; EPA Region 10 was
the least densely populated, with an average of approxi-
mately 15 people per square mile (including Alaska). The
national average in 2005 was 83.8 people per square mile.
4-20
EPA's 2008 Report on the Environment
-------
Urbanization and Population Change (continued)
gi if Population density (people per mi2) rn
hibit
600
500
400
300
200
100
0
600
500
400
300
200
100
0
erage
a sour
4-11. Population density in the U.S. by EPA Region, 1950-20053
Region 1
Jill
Region 2
II
Region 3
Region 4
Region 5
'50 '60 70 '80 '90 '00 '05 '50 '60 70 '80 '90 '00 '05 '50 '60 70 '80 '90 '00 '05 '50 '60 70 '80 '90 '00 '05 '50 '60 70 '80 '90 '00 '05
Region 7
Region 8
Region 9
Region 10
All U.S.
Region 6
'50 '60 70 '80 '90 '00 '05
EPA Regions
J^m [®
'50 '60 70 '80 '90 '00 '05 '50 '60 70 '80 '90 '00 '05 '50 '60 70 '80 '90 '00 '05 '50 '60 70 '80 '90 '00 '05 '50 '60 70 '80 '90 '00 '05
Year
50 states and the District of Columbia.
ce: U.S. Census Bureau, 2002a,c; 2006
Indicator Limitations
Census data:
Intercensal figures are estimates based on administrative re-
cords of births, deaths, and migration, and thus differ from
the decennial census data in methodology and accuracy.
• Sampling and non-sampling errors exist for all census
data as a result of errors that occur during the data col-
lection and processing phases of the census.
Puerto Rico and Virgin Islands data are not available for
all years, and thus have not been included. This affects
the accuracy of the statistics for Region 2.
The criteria for estimating urban population have
changed over time as defined by the Census Bureau.
NRI data:
NRI sampling procedures changed in 2000 to an annual
survey of fewer sample sites than had previously been
sampled (starting in 1977, the NRI sampled 800,000
points every 5 years). Fewer sample points mean in-
creased variance and uncertainty.
• The NRI collects some data across the entire nation,
including Puerto Rico and the Virgin Islands. Land use
statistics, however, are not reported on federal lands
or for Alaska and the District of Columbia. In Exhibit
4-10, Hawaii is also excluded.
Data Sources
Urban and rural population data for Exhibit 4-8 were
obtained from two U.S. Census Bureau publications: data
from 1790 to 1990 are from U.S. Census Bureau (1993);
2000 data are from U.S. Census Bureau (2004).
In Exhibit 4-9, population change was calculated from
annual population estimates published in U.S. Census Bureau
(1996, 2002b, 2006) (estimates for 1982/1987, 1992/1997, and
2002, respectively). Changes in acreage of developed land
were calculated based on acreage figures originally reported
every 5 years by the NRI and now reported annually. NRI
data were obtained from two publications (USDA NRCS,
2000, 2004) (1982-1997 and 2002 data, respectively).
Exhibit 4-10 is based on annual population estimates by
state, published in U.S. Census Bureau (1996, 2002b, 2006),
and NRI-developed land estimates by state, published in
USDA NRCS (2000, 2007). The figure was developed by
grouping the published state data by EPA Region, then cal-
culating percent change between 1982 and 2003.
Population density by EPA Region (Exhibit 4-11) was
calculated based on three published data sets: population
every 10 years from 1900 to 2000 by state (U.S. Census
Bureau, 2002a); population estimates for 2005 by state
(U.S. Census Bureau, 2006); and land area by state (U.S.
Census Bureau, 2002c).
EPA's 2008 Report on the Environment
4-21
-------
INDICATOR
Urbanization and Population Change (continued)
References
Frumkin, H., L. Frank, and R. Jackson. 2004. Urban sprawl
and public health: Designing, planning, and building for
healthy communities. Washington, DC: Island Press.
U.S. Census Bureau. 2006. Annual estimates of the popu-
lation for the United States, Regions, states, and for Puerto
Rico: April 1, 2000 to July 1, 2006 (NST-EST2006-01)
released December 22, 2006. Washington, DC. Available from
U.S. Census Bureau. 2004. Statistical abstract of the United
States 2004-2005: The national data book. Washington DC.
U.S. Census Bureau. 2002a. Demographic trends in the 20th
century: Census 2000 special reports. Washington, DC.
U.S. Census Bureau. 2002b. Time series of intercensal state
population estimates: April 1, 1990 to April 1, 2000. Table
CO-EST2001-12-00. Washington, DC.
U.S. Census Bureau. 2002c. Population, housing units, area,
and density for states, 2000. Washington, DC.
U.S. Census Bureau. 1996. Intercensal estimates of
the total resident population of states: 1980 to 1990.
Washington, DC.
U.S. Census Bureau. 1993. 1990 census of population
and housing: population and unit counts, United States.
1990-CPH-2-1. Washington, DC.
USDA NRCS (United States Department of Agriculture,
Natural Resources Conservation Service). 2007. National
Resources Inventory, 2003 annual NRI: Land use.
USDA NRCS. 2004. National resources inventory: 2002
annual NRI.
USDA NRCS. 2000. Summary report: 1997 national
resources inventory (revised December 2000). Washington,
DC and Ames, IA: USDA Natural Resource Conservation
Service,
4.3.3 Discussion
What These Indicators Say About Trends
in Land Use and Their Effects on Human
Health and the Environment
The indicators point out that the development of land for
human residential and commercial purposes is occurring at a
rapid pace. In the 21-year period between 1982 and 2003, the
acreage of developed land increased by more than 48 percent
from its 1982 level. Population in a similar time frame grew
at only half the rate of land development (25 percent), indi-
cating that more land is being developed per capita now than
25 years ago. Across EPA regions, such rates of change in
developed land and population vary both independently and
•with respect to each other. Over a similar 20-year time frame
(1982-2002), the extent of cropland and pastureland has slowly
declined, with larger decreases in those regions experiencing
either increased land development or reforestation.
Limitations, Gaps, and Challenges
There is generally a lack of comprehensive data on the types
and rates of land use and land cover change, and even less
systematic evidence on the causes and consequences of these
changes. On a global scale, the National Research Council
identified land use dynamics as one of the grand challenges for
environmental research.16
Two examples of land uses not addressed by the indicators,
that can have effects in different ways on condition and extent
of land, are the formal protection or reservation of land for
habitat or natural resources, and mining and extraction activi-
ties. Some data are collected locally and for federal lands (e.g.,
National Park acreage) or tracked for economic indicators, but
the national picture of the extent of land reservation and min-
ing is not generally available.
A key challenge in answering the land use question is that
estimates of the extent of various land uses differ across data
sources and each source uses different classifications, measure-
ment approaches, methodologies for analysis and interpretation,
National Research Council, Committee on Grand Challenges in Environ-
mental Sciences. 2001. Grand challenges in environmental sciences. Washing-
ton, DC: National Academies Press.
4-22
EPA's 2008 Report on the Environment
-------
and sampling time frames. The data are collected by many dif-
ferent agencies that manage land for many different purposes.
The data collection efforts currently in place are derived from
specific interests, such as tracking changes in the extent of agri-
cultural land or farmland, or understanding how much land is
used for timber production. These data collection efforts tend
to develop and use their own classifications and categoriza-
tion, making it difficult to integrate and use the data over time,
across inventories, or as a national picture.
Another challenge is understanding the effects that trends in land
use have on human health. No indicators are available, as effects
have not been shown or quantified on a national basis. Urban
and landscape planners have conducted site-specific studies on
individual land uses, but little is known about overall national
trends in land use and potential impacts on human health.
An additional challenge is that a variety of state, county,
and municipal laws, regulations, and practices govern the
use of land, but aside from regulations addressing protection
of species and their habitats, there are no national land use
regulations that apply to all non-federal lands. There are also
relatively few state-level efforts to organize land use data; most
activities occur over specific local, usually urbanizing, geo-
graphic areas. This means that land use records are not main-
tained state-wide or nationally, as they are in other nations,
•which contributes to challenges in tracking and monitoring
land use changes. It also means that strategies to plan land use
across jurisdictions are difficult to develop.
Finally, a challenge in developing data to determine trends
is the difficulty of actually delineating land use. Land use is
generally a function of laws, policies, or management designa-
tions that may not always be possible to infer from examining
the ground via surveys. Analysis of zoning maps or property
records at the local level may be necessary.
4.4 What Are the Trends in
Wastes and Their Effects
on Human Health and the
Environment?
4.4.1 Introduction
Every resident, organization, and human activity in the U.S.
generates some type of waste. Many different types of-wastes
are generated, including municipal solid waste, agricultural
and animal waste, medical waste, radioactive waste, hazard-
ous \vaste, industrial non-hazardous -waste, construction and
demolition debris, extraction and mining -waste, oil and gas
production -waste, fossil fuel combustion -waste, and sewage
17 Clark, R., and E. Capponi, eds. 2005. OECD in figures 2005: Statistics on the
member countries. Organization for Economic Cooperation and Develop-
ment (OECD) Observer. Paris, France.
18 U.S. Environmental Protection Agency. 2006. Inventory of U.S. greenhouse gas
emissions and sinks: 1990-2004. EPA/430/R-06/002.
sludge (see the glossary in Appendix A for detailed descrip-
tions of these -wastes). In general, -waste generation represents
inefficient use of materials. These materials, some of-which are
hazardous, must be managed through reuse, recycling, storage,
treatment, and disposal. Hazardous -wastes are either specifi-
cally listed as hazardous by EPA or a state, or exhibit one or
more of the folio-wing characteristics: ignitability, corrosivity,
reactivity, or toxicity. Generation and management of hazard-
ous -wastes have the potential to contaminate land, air, and
•water and negatively affect human health and environmental
conditions. Tracking trends in the quantity, composition,
and effects of these materials provides insight into the effi-
ciency -with -which the nation uses (and reuses) materials and
resources and provides a means to better understand the effects
of-wastes on human health and ecological condition.
The amount of-waste produced is influenced by economic
activity, consumption, and population growth. Affluent societ-
ies, such as the U.S., generally produce large amounts of munic-
ipal solid -waste (e.g., food -wastes, packaged goods, disposable
goods, used electronics) and commercial and industrial -wastes
(e.g., demolition debris, incineration residues, refinery sludges).
Among industrialized nations, the U.S. generates the largest
amounts of municipal solid -waste per person on a daily basis.17
Current approaches to -waste management evolved primar-
ily due to health concerns and odor control. Waste often -was
deposited outside developed areas on nearby lands, frequently
•wetlands. Excavation of land specifically for deposition of
•wastes followed, often accompanied by burning of wastes
to reduce volume, a practice eventually determined to be a
contributor to degraded air quality in urban areas. Burning of
•wastes occurred at multiple levels, from backyard burning to
large, open-burning dumps of municipal solid wastes to onsite
burning of commercial and industrial wastes. Land disposal
created problems such as ground water contamination, meth-
ane gas formation and migration, and disease vector hazards.
The amount of land being used to manage the many types of
•waste generated is not known. Most municipal solid wastes
and hazardous wastes are managed in land disposal units.
Land disposal of hazardous wastes includes landfills, surface
impoundments, land treatment, land farming, and underground
injection. Modern landfill facilities are engineered with con-
tainment systems and monitoring programs. Waste management
practices prior to the Resource Conservation and Recovery
Act (RCRA) regulations left legacies of contaminated lands in
many cases, which are addressed in Section 4.6 of this chapter.
Landfills represent one of the largest human-related sources
of methane gas in the U.S. Between 1997 and 2003, landfills
accounted for slightly more than one-fourth of the estimated
methane emissions attributed to human activity.18 Methane
gas is released as wastes decompose, as a function of the total
amount and makeup of the wastes as well as management
19 More information on air emissions related to waste management practices.
including nitrogen oxides (NOJ and carbon monoxide (CO), is included in
Chapter 2.
EPA's 2008 Report on the Environment
4-23
-------
facility location, design, and practices.19 EPA is interested
because gas emissions can be affected by recycling and chang-
ing product use. For example, recycling aluminum or office
paper can reduce environmental effects (e.g., by reducing the
need to mine bauxite or harvest trees), and it will also create
positive environmental benefits, such as reductions in energy
consumption and greenhouse gases (e.g., emissions associated
•with the production of products from virgin materials).20
Although data do not exist to directly link trends in waste
•with effects on human health and the environment, the
management of waste may result in waste and chemicals in
•waste entering the environment. Hazardous waste, by defini-
tion, has the potential to negatively affect human health and
the environment, which is why it is so strictly regulated. The
effects associated with waste vary widely and are influenced by
the substances or chemicals found in waste and how they are
managed. For chemicals found in waste, EPA has been track-
ing a list of Priority Chemicals. These Priority Chemicals are
documented contaminants of air, land, water, plants, and ani-
mals. Between 1991 and 2001, quantities of 17 of the Priority
Chemicals were reduced by more than 50 percent.21'22
4.4.2 ROE Indicators
The ROE indicators for this question focus on the national trends
in the amount of municipal solid waste and hazardous waste
generated and their management practices (Table 4-4). Munici-
pal solid \vaste trends are presented for more than four decades.
Trends in the generation and management of municipal solid
•waste are based on estimations from a materials flow or mass
balance approach since 1960. Changes in the amount of RCPvA
hazardous waste generated and managed are based on mandated
biennial submissions from generators and treatment, storage, and
disposal facilities.
Table 4-4. ROE Indicators of Trends in Wastes and Their
Effects on Human Health and the Environment
National Indicators
Quantity of Municipal Solid Waste Generated and Managed
Quantity of RCRA Hazardous Waste Generated and Managed
Section
4.4.2
4.4.2
4-24
4-26
INDICATOI
Quantity of Municipal Solid Waste Generated
and Managed
unicipal solid waste (also called trash or garbage) is
I defined at the national level as wastes consisting of
everyday items such as product packaging, grass clippings,
furniture, clothing, bottles and cans, food scraps, newspa-
pers, appliances, consumer electronics, and batteries. These
•wastes come from homes, institutions such as prisons and
schools, and commercial sources such as restaurants and
small businesses. EPA's definition of municipal solid waste
(MSW) does not include municipal -waste-water treatment
sludges, industrial process -wastes, automobile bodies, com-
bustion ash, or construction and demolition debris. Once
generated, MSW must be collected and managed, including
reuse, recovery for recycling (-which includes composting),
combustion, and landfill disposal. Many -wastes that are
disposed in landfills represent a loss of materials that could
be reused, recycled, or converted to energy to displace the
use of virgin materials.
Prior to the 1970s, MSW disposal generally consisted of
depositing -wastes in open or excavated landfills, accom-
panied by open burning to reduce -waste volumes. Often
industrial -wastes -were co-disposed -with municipal gar-
bage and refuse in urban and rural landfills. Historically,
environmental problems associated -with landfills have
included ground -water contamination, emissions of toxic
fumes and greenhouse gases, land contamination, and
increases in vector populations (e.g., rodents, flies, mosqui-
toes). Wastes have the potential to cause various types of
environmental concerns depending on the -way in -which
they are disposed. When mismanaged, potentially haz-
ardous ingredients in some products can migrate into the
environment, possibly posing harm to human health and
biota; stockpiled scrap tires may ignite, often burning for
months and causing air pollution; -waste piles can create
habitats for pests and disease vectors such as rodents and
U.S. Environmental Protection Agency. 2006. Solid waste management and
greenhouse gases:A life-cycle assessment of emissions and sinks.Third edi-
tion. Washington, DC.
U.S. Environmental Protection Agency. 2005. National Priority Chemicals
Trends Report (1999-2003). EPA/530/R-05/022.
U.S. Environmental Protection Agency. 2007. National Priority Chemicals
Trends Report (2000-2004). EPA/530/R-07/001.
4-24
EPA's 2008 Report on the Environment
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INDICATOI
Quantity of Municipal Solid Waste Generated
and Managed (continued)
mosquitoes; and the physical presence of a waste manage-
ment area can disrupt an ecosystem. Most wastes generated
in the U.S. are disposed in landfills, which are subject to
federal or state requirements to minimize environmen-
tal impacts. MSW landfills are discrete areas of land or
excavations that receive trash/garbage, as well as various
other types of wastes that are not included in this indica-
tor, such as non-hazardous sludges, hazardous wastes from
small quantity generators, non-hazardous industrial wastes,
municipal wastewater treatment sludges, and construction
and demolition debris.
This indicator shows trends in the national generation
and management of MSW on an annual basis from 1960 to
2006. The information presented on MSW consists of esti-
mates generated annually using a materials flow methodol-
ogy and mass balance approach that relies on production
data (by weight) for materials and products that eventu-
ally enter the waste stream. These data are collected from
industry associations, businesses, and government agencies.
What the Data Show
The quantity of MSW generated grew steadily from 88
million tons (MT) in 1960 to over 251 MT in 2006, an
increase of 185 percent (Exhibit 4-12, panel A). During
this time, the U.S. population increased by 66 percent.
On a per capita basis, MSW generation increased from
2.7 pounds per person per day in 1960 to 4.6 pounds per
person per day in 2006 (panel B).
Of the 88 MT of MSW generated in 1960, 6 percent was
recovered through recycling and 94 percent was landfilled
(Exhibit 4-13). MSW quantities sent to landfills or other
disposal peaked in 1990 at 142 MT and then began to
decline as recycling and combustion increased. The quantity
of MSW disposed in landfills has averaged about 135 MT
annually since 2000, a 4.9 percent decrease from 1990. In
2006, of the 251 MT generated, 32.5 percent was recycled
(including composting), 13 percent combusted with energy
recovery, and 55 percent landfilled. Since 1990, the percent-
age of MSW generated that was sent to landfills dropped
from 69 to 55 percent, the percentage recycled rose from
14 to 24 percent, the percentage composted rose from 2 to
8 percent, and the percentage combusted with energy-
recovery ranged from 13 to 15 percent.
Indicator Limitations
• The data in this indicator are derived from economic
statistics on materials generation and estimates of the
life cycle of goods, rather than on direct measurements
of \vastes disposed of. As a result of this methodology
and especially of differences in definitions, the figures
reported in this indicator do not match estimates of
Exhibit 4-12. Municipal solid waste generation
in the U.S., 1960-2006
300
250
1-C-
£ « 200
£ ^~
CD CO
>I 150
co =
S| 100
o -§•
^ ~~ 50
0
A. Total annual MSW generation
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
B. Per capita daily MSW generation
CD CD
0
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
Data source: U.S. EPA, 2007
Exhibit 4-13. Municipal solid waste
management in the U.S., 1960-2006
Combustion with energy recovery
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
Data source: U.S. EPA, 2007
EPA's 2008 Report on the Environment
4-25
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INDICATO
Quantity of Municipal Solid Waste Generated
and Managed (continued)
MSW reported elsewhere (e.g., BioCyde, which includes
construction and demolition debris, industrial wastes,
agricultural \vastes, etc., in its estimates). However, the
•waste categories in this indicator are rigorously defined
and consistent from year to year, therefore allowing for
reliable long-term trend analyses.
The data presented on landfills represent the amount
of \vaste disposed in landfills, but do not indicate the
capacity or volume of landfills or the amount of land
used for managing MSW. Land used for recycling facili-
ties and \vaste transfer stations also is not included in this
indicator. Data to describe the amount of land used or
total capacity of landfills are not available nationally.
The data also do not indicate the status or effectiveness
of landfill management or the extent to -which contami-
nation of nearby lands does or does not occur.
Data Sources
Exhibits 4-12 and 4-13 are derived from data published
in U.S. EPA (2007). The report provides tables with
numerical values for certain key years during the period
of record (1960, 1970, 1980, 1990, 1995, 2000, 2002, and
2004-2006). However, the full 44-year data set is not
publicly available.
References
U.S. EPA (United States Environmental Protection
Agency). 2007. Municipal solid waste generation, recy-
cling, and disposal in the United States: Facts and fig-
ures for 2006.
INDICATO
Quantity of RCRA Hazardous Waste Generated
and Managed
H
azardous -waste is -waste -with a chemi-
cal composition or other property that
40
35
)
30
^
C OK
° di
§ 20
1=
i 15
) -—-
10
makes it capable of causing illness, death, or
some other harm to humans and other life
forms -when mismanaged or released into
the environment. Uncontrolled dumping of
•wastes, including hazardous industrial -wastes,
•was commonplace in history, -with numerous
entities handling and disposing of these mate-
rials. Landfills and surface impoundments
containing these materials -were unlined and
uncovered, resulting in contaminated ground
•water, surface water, air, and soil. Even
•with tight control of hazardous wastes from
generation to disposal, the potential exists for
accidents that could result in the release of
hazardous wastes and their hazardous con-
stituents into the environment. Through the
Resource Conservation and Recovery Act
(RCRA) and the subsequent 1984 Hazard-
ous and Solid Waste Amendments, Congress
sought to better control waste management and disposal and
to conserve valuable materials and energy resources.
Facilities that treat, store, or dispose of hazardous wastes
are termed RCRA treatment, storage, and disposal facilities
(TSDFs). Some hazardous waste generators treat, store, and
dispose of their hazardous waste onsite, while others ship
Exhibit 4-14. RCRA hazardous waste generation and
management in the U.S., 1999-20053
Generated
Stored/
bulked/
transferred
Material
recovery
Energy
recovery
Treated
Disposed
'99 '01 '03 '05 '99 '01 '03 '05 '99 '01 '03 '05 '99 '01 '03 '05 '99 '01 '03 '05 '99 '01 '03 '05
Year
Individual management practice quantities do not add up to the total quantity
generated. See text for details.
Data source: U.S. EPA, 2007b
their waste to TSDFs. Most hazardous wastes are eventually
disposed in landfills, surface impoundments (which even-
tually become landfills), land application units, or by deep
•well injection. All hazardous wastes disposed of must meet
certain treatment standards required by the Land Disposal
Restrictions prior to disposal.
4-26
EPA's 2008 Report on the Environment
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INDICATOI
Quantity of RCRA Hazardous Waste Generated
and Managed (continued)
Exhibit 4-15. RCRA hazardous waste disposal
to land in the U.S. by practice, 1999-2005
£ 30
o
§ 25
£ 20
0
o 15
^ 10
CO
i 5
[004]
2.5
26.9
rr^i lo.oosl
21.6
1.7
19.7
25
22.3
D Land treatment/
land application
n Landfill/surface
impoundment
n Underground
injection
1999 2001 2003 2005
Year
Data source: U.S. EPA, 2007b
EPA, in partnership with the states, collects extensive data
on the RCRA hazardous waste generation and management
practices of TSDFs and large quantity generators (businesses
that generate more than 2,200 pounds of RCRA hazardous
•waste, 2.2 pounds of RCRA acute hazardous waste, or 220
pounds of spill cleanup material contaminated with RCRA
acute hazardous waste in 1 month). These data are col-
lected every 2 years; this indicator tracks changes in RCRA
hazardous wastes generated and managed for the years 1999,
2001, 2003, and 2005.
What the Data Show
Between 1999 and 2005, the quantity of RCRA hazardous
•wastes generated decreased by 22 percent from 36.1 million
tons (MT) to 28.0 MT (Exhibit 4-14). Included in the amount
generated are material recovery, energy recovery, treatment,
and \vastes disposed by deep well injection. Due to RCRA
hazardous waste regulations and data collection procedures,
the individual management categories discussed below cannot
be added together to obtain the total quantity generated. For
example, under RCRA, all hazardous waste must be treated
to meet technology-based land disposal treatment standards
before it is placed in or on the ground, unless it meets those
standards as generated. To minimize double-counting, the
quantities of waste stored, bulked, transferred, or disposed by
landfill, land treatment, or land application after treatment are
not included in the total quantity generated, but are shown
in the "Disposed" section of Exhibit 4-14 (along with -wastes
disposed by deep -well injection).
In addition to the 36.1 MT of RCRA -waste generated
in 1999, 0.7 MT -were stored/bulked/transferred for some
time prior to final disposition (at which time they -would be
included in -wastes recovered, treated, or disposed) (Exhibit
4-14). In 2005, the number stored/bulked/transferred rose
to 0.8 MT.
Looking at management activities prior to disposal, in
1999, 7 percent of RCRA hazardous -waste -was sent to
material recovery activities such as metal or solvent recov-
ery, -while 8 percent fell into this category in 2005 (Exhibit
4-14). The proportion of RCRA hazardous -waste sent for
energy recovery increased from 4 percent of RCRA -wastes
generated in 1999 to 6 percent in 2005. The proportion
sent to treatment declined from 14 percent in 1999 to 7
percent in 2005.
The quantity of RCRA hazardous -wastes ultimately dis-
posed dropped between 1999 and 2005, from 29.5 MT to
24.9 MT; however, the proportions of-waste in the three
disposal categories remained fairly stable (Exhibit 4-15).
In the four reporting cycles shown, the percentage of dis-
posed RCRA hazardous -wastes deep-well injected ranged
from 90 to 92 percent of all -waste disposed on land. The
proportion disposed in landfills or surface impoundments
that became landfills ranged between 8 and 10 percent.
The land application and land treatment categories repre-
sent a very small percentage of disposal and dropped from
0.1 percent in 1999 to 0.01 percent of the RCRA hazard-
ous -waste disposed in 2005.
Indicator Limitations
• Data are not collected from small quantity genera-
tors, but some -wastes coming from these sources are
included in the RCRA hazardous -waste management
data from treatment, storage, and disposal facilities that
receive the -wastes.
• Data are limited to -wastes referred to as "RCRA
hazardous -waste" -which are either specifically listed
as hazardous or meet specific ignitability, corrosivity,
reactivity, or toxicity criteria found in the U.S. Code of
Federal Regulations Title 40, Part 261. Materials that
are not -wastes, -whether hazardous or not, are not regu-
lated by RCRA, and therefore are not included in the
data summarized here.
States have the authority to designate additional -wastes
as hazardous under RCRA, beyond those designated in
the national program. State-designated hazardous -wastes
are not tracked by EPA or reflected in the aggregated
information presented.
The comparability of year-to-year amounts of RCRA
hazardous -waste generated and managed can be influ-
enced by factors such as delisting -waste streams (i.e.,
determining that a particular listed -waste stream coming
from a particular facility is not hazardous) or removing
the hazardous characteristic of a -waste stream.
EPA's 2008 Report on the Environment
4-27
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INDICATOI
Quantity of RCRA Hazardous Waste Generated
and Managed (continued)
The data summarized and shown in Exhibits 4-14
and 4-15 were derived from the data and information
collected and reported in the Biennial RCRA Hazard-
ous Waste Report Forms (U.S. EPA, 2007a). As a result
of methodology and criteria used to derive the results
for these two exhibits, the quantities presented in this
indicator do not match those individual generation or
management quantities presented in each reporting
cycle of the National Biennial Reports. The National
Biennial Reports are prepared for individual reporting
cycles and may not be comparable between reporting
cycles due to different reporting requirements or meth-
ods of aggregation in each cycle.
Most hazardous waste generated in the U.S. is in the form
of wastewater. The majority of these wastewaters are sent
untreated to publicly owned treatment works (POTWs),
treated and sent to a POTW, or discharged directly to
surface waters through a National Pollutant Discharge
Elimination System (NPDES) permit. Hazardous waste-
waters generated and subsequently sent to POTWs or
discharged through a NPDES permit are not included in
this indicator. Any materials generated from these pro-
cesses, such as sludge, that are considered hazardous waste
are managed under hazardous waste regulations.
Data Sources
This indicator is based on the publicly available data sets
compiled by EPA. The data sets compiled from indi-
vidual reporting facilities for this indicator can be found
in National Biennial RCRA Hazardous Waste Data Files
in EPA's RCRAInfo national database (U.S. EPA, 2007b)
(http://www.epa.gov/epaoswer/hazwaste/data/index.
htm#rcra-info; ftp://ftp.epa.gov/rcrainfodata).
Exhibits 4-14 and 4-15 are derived from reported data
stored in these data files of the RCRAInfo national data-
base. The versions of data sets from each reporting cycle to
derive the results for this indicator -were downloaded from
the FTP site between February 2007 and August 2007.
The analyses based on the data sets downloaded -were con-
ducted in October 2007.
References
U.S. EPA (United States Environmental Protection
Agency). 2007a. Biennial RCRA hazardous -waste report
instructions and forms. Accessed December 2007.
U.S. EPA. 2007b. RCRAInfo national database. Accessed
December 2007.
4.4.3 Discussion
What These Indicators Say About Trends in
Wastes and Their Effects on Human Health
and the Environment
The indicators show that municipal solid waste generation
in the U.S. continued to rise between 1960 and 2006, in
absolute terms. On a per capita basis, rates rose from 1960 to
1990; however, since 1990, the daily per capita generation of
municipal solid waste has been relatively constant, showing
that the total increase in waste may be primarily a function
of population growth. Hazardous waste, which is generated
primarily through industrial processes, decreased in the time
period shown from 1999 to 2005, although there was a small
rise between 2003 and 2005.
Materials recovery, or recycling, is an important component of
•waste management, as it takes materials that might be con-
sidered waste and removes them from the waste disposal path
to generate reusable marketable materials. Recycling efforts
related to municipal solid waste have increased over the last
four decades, showing the steepest increases between 1980 and
2000. Municipal solid waste recycling efforts have been steady
since 2000, with nearly a third of all municipal solid waste
being recycled or composted.
Recycling (material recovery and energy recovery) of hazard-
ous \vastes has remained relatively constant over the time span
represented by the indicators, although there has been a slight
decrease in the amount of waste sent for materials recovery.
While recycling and composting have increased over the past
several decades, most-wastes are disposed. Disposal of munici-
pal solid -wastes in landfills saw a rise in absolute amount from
1960 to 1990, -with declines since then. Landfill as a per-
centage of total -waste generated, however, has seen a steady
decline from 1960 to 2006. Similarly, most hazardous -wastes
are also land-disposed, although they are required to meet
strict standards for protecting human health and the environ-
ment prior to disposal.
Limitations, Gaps, and Challenges
While numerous -waste-related data collection efforts exist at
the local, state, and national levels, none of these efforts result
in nationally consistent or comprehensive data to provide a
full understanding of the amount and locations of-waste gen-
eration and management.
The two types of-waste addressed in the indicators represent
only a small percentage of the total amount of-waste gener-
ated in the U.S.—the national amounts and percentage of
total-waste are unknown. Quantities of "end-of-stream"
•wastes, such as municipal solid -waste, provide an indication
4-28
EPA's 2008 Report on the Environment
-------
of changing trends in consumption and economic activities,
but do not provide information on the other amounts of waste
generated by upstream activities, including resource extraction
and manufacturing. EPA is interested in better understanding
the comparative amounts of the various types of waste gener-
ated, but national data are dated, inconsistent, or generally not
available in common units to develop a comprehensive picture
of the waste generated in the U.S.
The amount of waste generated and managed may describe
ambient conditions in terms of wastes in the environment, but
does not provide any indication of the effects on human health
or environmental condition. There have been changes in the
management of wastes over the past few decades, designed to
reduce hazardous and potential exposures, but data that more
concretely measure the overall exposure (and thus effects on
human health and the environment caused by wastes and
•waste management practices) are still lacking.
4.5 What Are the Trends
in Chemicals Used on the
Land and Their Effects
on Human Health and the
Environment?
4.5.1 Introduction
Many chemicals and chemical products are considered essential
to modern life because of the benefits they provide. Some break
down quickly, while others persist for long periods of time in
the environment and may bioaccumulate in the food chain
(e.g., persistent, bioaccumulative, and toxic chemicals [PBTs]).
Introduction of chemicals into the environment occurs
through acts of nature (e.g., volcanoes, hurricanes), spills on
land, emissions to air, and discharges to water. Chemicals
can be released through large- and small-scale industrial and
manufacturing activity, in the production and storage of food
and consumer products, in efforts to manage or eradicate
insect-borne diseases (e.g., West Nile virus, Lyme disease), or
through personal actions such as the use and improper disposal
of household products (e.g., lawn care materials, pharmaceuti-
cals, cleaning products, batteries, paint, automotive products)
or \vastes. Deliberate application of chemicals to the land is
•widespread in agricultural production to increase crop yields
and control fungi, weeds, insects, and other pests.
Tracking trends in the use and disposition of chemicals in the
U.S. is important to better understand the potential for those
chemicals to affect human health and the environment. Many
chemicals pose little known hazard to human health or environ-
mental condition, while others pose risk. Many chemicals are
U.S. Department of Health and Human Services. 2005. Report on carcino-
gens. Eleventh edition.Washington, DC: Public Health Service, National
Toxicology Program.
recognized as carcinogens.23 The effects of chemicals on human
health and other ecological receptors through environmental
exposure can be acute and very toxic, subtle and cumulative over
time, or nonexistent. Chemicals can be of concern because of
their pervasiveness, potential to accumulate, possibilities of inter-
action, and often long-term unknown effects on people and the
environment (e.g., cancer, mercury in fish). Humans and wildlife
may be affected by certain chemicals through direct exposure,
including accidental ingestion or inhalation, accumulation and
uptake through the food chain, or dermal contact.
Similarly, ecosystems and environmental processes may be com-
promised or contaminated through the migration and accumu-
lation of chemicals (e.g., via uptake by plants, fugitive dust and
volatilization, and migration to water supplies). For example,
excessive nutrient loading from over-fertilization can result
in runoff that causes adverse effects in aquatic ecosystems.24
Widespread exposure to, or misuse of, pesticides can harm non-
targeted plants and animals (including humans), as well as lead
to development of pesticide-resistant pest species.
It is difficult to make generalizations about the effects of
chemicals and chemical usage, not only because there are
thousands of chemicals, but also because individual chemicals
have unique ways of being absorbed and handled by living
organisms. The risks associated with chemicals are dependent
on many factors, including exposure and toxicity—which
can be acute or chronic, and can occur at multiple stages of
the chemical life cycle. Different stages in the life cycle of
chemicals, such as manufacturing, transport, application or
use, runoff, or accumulation, pose different hazards to humans
and the environment.
4.5.2 ROE Indicators
The amounts and types of chemicals applied or released
to land through agricultural fertilizers are examined as a
National Indicator displayed at EPA Regional scale. Three
other National Indicators are examined, including toxic
chemicals in production-related -wastes, pesticide residues in
food, and occurrences of pesticide-related incidents reported
to poison control centers (Table 4-5).
Trends in the amount of fertilizer used are based on sales data
provided by major crop-producing states through a survey
conducted each year since 1960. Acreage estimates are from
an agricultural census of the 48 contiguous states conducted
every 5 years since 1954. Trends in the quantities of Toxics
Release Inventory-reported chemical releases are based on
annual reports required since 1998 from facilities that meet
certain size and usage criteria. Trends in the detection of
pesticide residues in food are derived from randomly sampled
data collected daily since 1993 from participating states for
over 50 different commodities. Trends in reported pesticide
incidents are from a pesticide surveillance system that collects
data annually from poison control centers around the nation.
Boesch, D.E, D.M.Anderson, R.A. Homer, S.E. Shumway, PA.Tester, and
T.E.Whitledge. 1997. Harmful algal blooms in coastal waters: Options for
prevention, control, and mitigation. NOAA Coastal Ocean Program Decision
Analysis Series No. 10.
EPA's 2008 Report on the Environment
4-29
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Table 4-5. ROE Indicators of Trends in Chemicals Used on the Land and Their
Effects on Human Health and the Environment
National Indicators
N/R = National Indicator displayed at EPA Regional scale
Section
Fertilizer Applied for Agricultural Purposes (N/R)
Toxic Chemicals in Production-Related Wastes Combusted for Energy
Recovery, Released, Treated, or Recycled
Pesticide Residues in Food
Reported Pesticide Incidents
4.5.2
4.5.2
4.5.2
4.5.2
4-30
4-33
4-37
4-39
INDICATOR
Fertilizer Applied for Agricultural Purposes
Commercial fertilizers are applied to agricultural crops
to increase crop yields. Prior to the 1950s, most farm-
ing occurred on small family farms with limited use of
chemicals. The shift since then to larger corporate farms
has coincided with the use of chemical fertilizers in mod-
ern agricultural practices. The three major types of com-
mercial fertilizer used in the U.S. are nitrogen, phosphate,
and potash.
Nitrogen (N) is found primarily in the organic form
in soils, but can also occur as nitrate. Because nitrate is
extremely soluble and mobile, it can lead to nuisance algal
growth, mostly in downstream estuaries, and cause con-
tamination of drinking water. Phosphorus (P) occurs in soil
in several forms, both organic and inorganic. Phosphorus
loss due to erosion is common and phosphate, while less
soluble than nitrate, can easily be transported in runoff.
Phosphorus/phosphate runoff can lead to nuisance algae
and plant growth, often in freshwater streams, lakes, and
estuaries. Potash is the oxide form of potassium (K) and its
principal forms as fertilizer are potassium chloride, potas-
sium sulfate, and potassium nitrate. When used at recom-
mended application rates, there are few to no adverse effects
from potassium, but it is a common component of mixed
fertilizers used for high crop yields and is tracked in the
fertilizer use surveys conducted.
This indicator shows use of the three major fertilizers in
pounds per acre of land per year (expressed as N, P, or K)
used for crop production from 1960 to 2005. Data are from
an annual survey for agricultural crops conducted by the U.S.
Department of Agriculture (USDA) National Agricultural
Statistics Service (NASS) and from the Economic Research
Service (ERS) Major Land Use series. Acreage used for crop
production includes cropland harvested and crop failure
as estimated in the ERS series. Cropland estimates as used
in this indicator are a subset of agricultural land estimates
discussed in the Land Cover and Land Use indicators. NASS
also produces an annual Agricultural Chemical Usage report on
four to five targeted field crops, based on data compiled from
the Agricultural Resources Management Survey (ARMS).
The ARMS surveys farmers in major agriculture-producing
states that together account for a large percentage of crop
acreage for corn, soybeans, cotton, and wheat. Results are
presented for the years 2005-2006 by EPA Region.
What the Data Show
Based on fertilizer sales data, total use of the three major
commercial fertilizers has steadily increased, from 46.2
nutrient pounds per acre per year (Ibs/acre/yr) in 1960 to
138 Ibs/acre/yr in 2005, an increase of 199 percent (Exhibit
4-16). During this period, cropland used for crop produc-
tion generally has fluctuated between 290 and 360 million
acres with the largest changes occurring between 1969
(292 million acres) and 1981 (357 million acres) (Lubowski
et al., 2006). Since 1996, cropland used for crop production
has ranged between 321 and 328 million acres (Lubowski
et al., 2006). Since 1996, aggregate commercial fertilizer
use has fluctuated between 129 and 145 Ibs/acre/yr with
peak usage in 2004. Since 1960, nitrogen accounted for the
steepest increase in use, from 17.0 Ibs/acre/yr in 1960 to
81.6 Ibs/acre/yr in 2004. Nitrogen currently accounts for
about 56 percent of total fertilizer use, up from 37 percent
in 1960. During the same period, phosphate and potash use
grew more slowly; they remained steady between 25 and
36 Ibs/acre/yr each since the late 1960s and now account
for approximately 21 percent and 23 percent of total fertil-
izer usage, respectively.
The four major crops in the U.S.—corn, cotton, soy-
beans, and wheat—account for about 60 percent of the
principal crop acreage and receive over 60 percent of the
N, P, and K used in the U.S. Estimates from annual NASS
4-30
EPA's 2008 Report on the Environment
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Fertilizer Applied for Agricultural Purposes (continued)
Acreage reports show that from 1995 to 2006, between 76
and 80 million acres of corn were planted annually. In
2007, nearly 93 million acres were planted (USDA NASS,
2007a). A total of 76.5 million acres of corn were planted
during the survey year (2005-2006). Corn acreage is con-
centrated in the center of the country (EPA Regions 5 and
7), but most EPA Regions grow some corn. Corn typically
accounts for more than 40 percent of commercial fertilizer
used (Daberkow and Huang, 2006).
The acreage of land planted in cotton was 12.4 million
acres in the most recent ARMS survey year (2006) and has
ranged between 11 and 16 million acres since 1990. Major
cotton-producing states include 17 southern states located
in EPA Regions 4, 6, and 9.
Production of winter, durum, and other spring wheat
occurred on about 57 million acres in 2006 and is distrib-
uted across EPA Regions 5, 6, 7, 8, and 10. Wheat typically
accounts for about 10 percent of all commercial fertilizer
used (Daberkow and Huang, 2006).
Soybeans were the fastest-growing crop in total acreage,
increasing from 57.8 million acres in 1990 to 75.5 mil-
lion acres in 2006 (USDA NASS, 2007c). The majority of
soybean acreage (80 percent) is concentrated in the upper
Midwest in EPA Regions 5 and 7. Soybeans require the
least fertilizer per acre of the four crops described here.
Overall, production of these four crops in the ARMS states
used slightly more than 13.25 million tons per year (MT/yr)
of fertilizer in 2005-2006 (Exhibit 4-17) of the 21.7 MT/yr
estimated (2005-2006 average) by ERS for all crops produced
in the entire U.S. Of this amount, slightly less than half (5.8
MT/yr) was applied in EPA Region 5 (Exhibit 4-17), most
of which was used for corn. An additional 3.7 MT/yr was
applied in EPA Region 7, primarily on corn or soybeans.
Indicator Limitations
• USDA national estimates of fertilizer use are based on
sales data provided by states, not actual fertilizer usage,
and are susceptible to differing reporting procedures or
accuracy from state to state.
Data to identify cropland used for crop production are
from the major land use series discussed in the Land
Cover and Land Use indicators (pp. 4-7 and 4-14,
respectively) and do not include Alaska and Hawaii.
• Within the ARMS, not all states report fertilizer data
every year for each crop type, making it difficult to
establish year-to-year trends (a decrease in fertilizer use
for a specific crop might be attributed to failure of a
state to report, rather than an actual decrease of use).
• ARMS sampling is limited to program states, which
represent 82 to 99 percent of crop acreage (across all
surveyed crops) for the years 2005 and 2006, depending
on crop type.
Exhibit 4-16. Commercial fertilizer use in the
U.S., 1960-2005a
J60
i
[140
'• 100
;
[ 80
i 60
i
j- 40
i 20
Total
Phosphate
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
aBased on sales data. Per-acre use based on the acreage of
harvested or failed cropland, as determined by USDA's National
Agricultural Statistics Service.
Data source: Lubowski, 2006; Wiebe and Gollehon, 2006
Exhibit 4-17. Fertilizer use for four common
crops (corn, cotton, soybeans, and wheat) in
major agriculture-producing states, by EPA
Region, 2005-20063
r 6
-------
INDICATOR
Fertilizer Applied for Agricultural Purposes (continued)
• The NASS Acreage report has estimates of acreage in
production for the entire nation by crop, while fertilizer
sales data are based only on USDA program states. Even
though USDA program states represent the majority of
U.S. planted acreage (often over 90 percent), the abil-
ity to generalize the data to the country as a whole is
unknown, as non-program states, while representing a
small percentage of a crop, might have much different
application rates due to climate, weather, etc.
• Fertilizer applied to trees that are considered agricul-
tural crops (e.g., nut-producing trees) is included in field
crop summaries, but fertilizer applied in silviculture
(e.g., southern pine plantations) is not covered by the
NASS data collection system.
Loading of nutrients in aquatic systems is not necessarily
correlated directly with fertilizer use, but rather with the
levels of fertilizer applied in excess of amounts used by
crops, natural vegetation, and soil biota.
Data Sources
Exhibit 4-16 is based on two sets of summary data
from ERS. Annual estimates of fertilizer use from 1960
through 2005, by nutrient, were obtained from Wiebe
and Gollehon (2006) (see summary tables, http://www.
ers.usda.gov/Data/FertilizerUse/). Fertilizer use per acre
\vas calculated based on annual estimates of the amount
of cultivated (harvested or failed) cropland from 1960 to
2005 published in Lubowski et al. (2006) (see summary
tables, http://www.ers.usda.gov/Data/MajorLandUses/
MLUsummarytables.pdf).
Exhibit 4-17 is based on fertilizer use data from USDA's
2005 and 2006 ARMS survey, which were obtained from
USDA NASS (2006b, 2007b). The published data are by
state, so additional aggregation was required to report by
EPA Region (USDA NASS, 2001, 2004, 2005a,b, 2006a).
References
Daberkow, S., and W. Huang. 2006. Nutrient manage-
ment. In: Wiebe, K., and N. Gollehon, eds. 2006. Agricul-
tural resources and environmental indicators, 2006 edition.
EIB-16. U.S. Department of Agriculture, Economic
Research Service,
Lubowski, R.N., M. Vesterby, S. Bucholtz, A. Baez, and
MJ. Roberts. 2006. Major uses of land in the United States,
2002. EIB-14. U.S. Department of Agriculture, Economic
Research Service.
USDA NASS (United States Department of Agriculture,
National Agricultural Statistics Service). 2007a. Acreage.
USDA NASS. 2007b. Agricultural chemical usage, 2006
field crop summary. May.
USDA NASS. 2007c. Crop Production Historical Track
Records,
USDA NASS. 2006a. Acreage.
USDA NASS. 2006b. Agricultural chemical usage,
2005 field crop summary. May.
USDA NASS. 2005a. Acreage.
USDA NASS. 2005b. Crop production: 2004 summary.
Cr Pr 2-1 (05).
USDA NASS. 2004. Acreage.
USDA NASS. 2001. Agricultural chemical usage, 2000
field crops summary,
Wiebe, K., and N. Gollehon, eds. 2006. Agricultural
resources and environmental indicators, 2006 edition.
EIB-16. U.S. Department of Agriculture, Economic
Research Service,
4-32
EPA's 2008 Report on the Environment
-------
Toxic Chemicals in Production-Related Wastes Combusted
for Energy Recovery, Released, Treated, or Recycled
Toxic chemicals are contained in waste materials produced
by a wide variety of industrial activities, in both public
(e.g., sewage treatment plants) and private facilities. These
chemical wastes are really a composite matrix of various
chemicals, some of which may be hazardous or toxic, and
therefore are subject to reporting under the Toxics Release
Inventory (TRI) program. Some of these chemicals are
released onsite or offsite to air, water, or land (including sur-
face impoundments and underground injection wells). The
rest are treated, recycled, or combusted for energy recovery.
Reductions in the quantities of TRI chemicals are desirable
from both environmental and economic perspectives. TRI
chemicals have known toxic properties, rendering them
potentially hazardous to workers in both production and
•waste management facilities, and more generally to eco-
systems and human health. As elements of overall business
strategies, companies target waste reduction in ways that
reduce costs and increase profits.
This indicator tracks trends in the amounts of toxic
chemicals in production-related wastes that contain
reported TRI chemicals which are either released to the
environment or treated, recycled, or combusted for energy
recovery. Toxic chemicals in non-production-related
•waste, such as might be associated with catastrophic events
and remedial actions (cleanup), are not included in this
indicator because they are not directly related to routine
production practices.
TRI contains information on more than 650 chemicals
and chemical categories from nine industry sectors, includ-
ing manufacturing operations, certain service businesses,
and federal facilities. Facilities are required to report to
TRI if they employ 10 or more employees, are covered by
a North American Industry Classification System code cor-
responding to a TRI-covered Standard Industrial Classifica-
tion code, and manufacture more than 25,000 pounds, and/
or process more than 25,000 pounds, and/or other-wise use
more than 10,000 pounds of a TRI-listed non-persistent,
bioaccumulative, toxic (non-PBT) chemical during a calen-
dar year. In addition, EPA has lowered the TRI reporting
thresholds for certain PBT chemicals (i.e., to 100 pounds or
10 pounds, except for dioxin and dioxin-like compounds,
•which have a threshold of 0.1 gram) and added certain other
PBT chemicals to the TRI list of toxic chemicals. These
PBT chemicals are of particular concern not only because
they are toxic but also because they remain in the environ-
ment for long periods of time, are not readily destroyed, and
build up or accumulate in body tissue (U.S. EPA, 2002b).
EPA currently requires reporting of 16 PBT chemicals
and four PBT chemical compound categories (U.S. EPA,
2007b). In 2005, 23,500 facilities reported to TRI (U.S.
EPA, 2007d).
TRI is national in coverage and includes all U.S. ter-
ritories. Because the reporting requirements for TRI have
varied somewhat between 1998 and 2005 (the most recent
year for which annual data reports are available in TRI),
chemicals that were reported consistently from year to year
over this period are presented separately in this indicator.
Facilities that manufacture, process, or other-wise use PBT
chemicals have lower reporting thresholds as established in
2000 and 2001; hence these data are depicted separately in
the exhibits. Similarly, metal mining sector land releases
are analyzed separately because a 2003 court decision
altered the scope of TRI reporting of these quantities
(U.S. EPA, 2007a).25
What the Data Show
In 2005 the quantities of TRI non-PBT chemicals associ-
ated \vith production-related -wastes tracked in this indicator
totaled 23.6 billion pounds (Exhibit 4-18, panel A). These
quantities have decreased by more than 4 billion pounds
(15.7 percent) since 1998. The decrease -was gradual over
time -with the exception of the year 2000, -which saw an
increase of 4.3 billion pounds from the previous year. The
2000 increase is attributed to a few facilities that reported
large amounts of onsite treatment and onsite recycling (U.S.
EPA, 2002a). The amount of TRI non-PBT chemicals
reported as treated varied between 1998 to 2005, from a
high of nearly 13 billion pounds in the year 2000 to a low of
8 billion pounds in 2002. In 2005, the amount treated -was
8.6 billion pounds or 2.9 percent more than in 1998. The
amount of TRI non-PBT chemicals recycled declined by
1 billion pounds (11.6 percent) from 1998 to 2005, varying
from a high of 9.6 billion pounds in 2000 to the low of 8.2
billion pounds in 2005. TRI non-PBT chemicals man-
aged through energy recovery processes showed a decline
of 0.62 billion pounds (17.2 percent) in the 8-year period,
fluctuating between 3.0 and 3.7 billion pounds. Some of the
year-to-year fluctuations may reflect changes in aggregate
production levels in the national economy.
Reported PBT chemicals totaled 1.13 billion pounds in
2005, having declined by 0.18 billion pounds (13.9 percent)
over recent years since 2001 (Exhibit 4-18, panel B). The
amount of PBT chemicals recycled declined by 26.6 per-
cent between 2001 and 2005 (0.22 billion pounds).
Excluding metal mining and PBT chemical releases,
approximately 3.1 billion pounds of toxic chemicals -were
The metal mining sector consists of facilities that fall within Standard
Industrial Classification Code 10 and must report to TRI in accordance
with Section 313 of the Emergency Planning and Community Right to
Know Act.
EPA's 2008 Report on the Environment
4-33
-------
Toxic Chemicals in Production-Related Wastes Combusted
for Energy Recovery, Released, Treated, or Recycled (continued)
released offsite or onsite to air, land, or water in 2005.
The 3.1 billion pounds of releases in 2005 are 18.6 percent
less than the amount reported in 1998 (Exhibit 4-19,
panel A). The remaining 19.6 billion pounds of non-PBT
chemicals from all TRI sectors except metal mining were
managed (onsite or offsite) through treatment, recycling,
and energy recovery processes and represent an 8 percent
decline from 1998.
Excluding metal mining releases, nearly 0.082 billion (82
million) pounds of PBTs were released offsite or onsite to air,
land, or water in 2005 (Exhibit 4-19, panel B). The remain-
ing approximately 0.725 billion (725 million) pounds were
managed (onsite or offsite) through treatment, recycling, and
energy recovery processes. The amounts of reported PBT
releases (excluding metal mining) have fluctuated, ranging
from approximately 110 million pounds in 2003 to 79 million
pounds in 2004 and 83 million pounds in 2005.
Between 1998 and 2005 there were also distinct trends
in media-specific and offsite releases of non-PBT toxic
chemicals (Exhibit 4-19, panel A). All of these releases
exclude metal mining. Air releases declined by 28.1
percent (585 million pounds) between 1998 and 2005.
Releases to surface waters decreased by 2 percent (nearly
6 million pounds) and land releases dropped by nearly 18
percent (183 million pounds). Offsite releases, which can-
not be apportioned by medium in TRI, rose by 72 million
pounds or 18 percent from 1998 to 2005.
PBT chemicals (also excluding metal mining) released
to air increased nearly 108 percent (3 million pounds)
(Exhibit 4-19, panel B). PBT releases to land decreased 24
percent (14 billion pounds) and to water 22 percent (0.035
million pounds). Offsite PBT releases increased nearly 8
percent (2.3 million pounds).
Excluding PBT chemicals, the metal mining sector
accounted for 35 percent of the total production-related
•wastes released to the environment over the 8-year period
from 1998 through 2005, releasing approximately 14 billion
pounds of total production-related wastes (Exhibit 4-20,
panel A) compared to 27 billion pounds reported by all
other industry sectors (Exhibit 4-19, panel A). Nearly all of
the production-related wastes managed by metal mining
facilities were releases to land. There is a downward trend
for the quantities of total releases reported by the metal
mining sector from 2001 to 2005 (Exhibit 4-20, panel A).
In 2001, the metal mining industry reported nearly 2 billion
pounds in total releases, and in 2005, only 0.77 billion
pounds were reported. Part of this trend can be attributed
to the court decision (Barrick Goldstrike Mines, Inc., v. EPA]
in 2003, in which the court determined that non-PBT
chemicals present in the waste rock below concentrations
of 1 percent (or 0.1 percent for Occupational Safety and
Health Administration defined carcinogens) are eligible for
Exhibit 4-18. Quantities of toxic chemicals
combusted for energy recovery, released,
recycled, and treated in the U.S., as reported to
EPA's Toxics Release Inventory, 1998-2005abc
A. Non-PBT chemicals (1998-2005)
JO
to 30
c
= nc
Q_
d
.2 20
15
^ 15
1 10
-------
Toxic Chemicals in Production-Related Wastes Combusted
for Energy Recovery, Released, Treated, or Recycled (continued)
Exhibit 4-19. Quantities of toxic chemicals released in the U.S., by type of release (excluding metal
mining), as reported to EPA's Toxics Release Inventory, 1998-2005ab
2,500
2,000
1,500
A. Non-PBT chemicals (1998-2005)
II
_o
o
CO
.§ :§ 1,000
500
Onsite land releases
Onsite air releases
Onsite surface water discharges
Offsite disposal and
other releases
'99 '00 '01 '02 '03 '04 '05
'99 '00 '01 '02 '03 '04 '05
'99 '00 '01 '02 '03 '04 '05
Year
B.PBT chemicals (2001-2005)
8.2
100
60
40
20
Onsite land releases
Onsite air releases
Onsite surface water discharges
Offsite disposal and
other releases
0.16 0.12 0.14 0.13 0.12
'01 '02 '03 '04 '05
'01 '02 '03 '04 '05
'01 '02 '03 '04 '05
'01 '02 '03 '04 '05
Year
Coverage: Production-related waste from facilities required to report to TRI, including more than 650 chemicals and chemical categories.
Persistent, bioaccumulative, and toxic (PBT) chemicals are presented separately because reporting thresholds were changed partway through
the period of record.
bSome waste quantities may be double-counted when waste has been transferred from one TRI facility (which has counted waste as offsite
disposal or as other releases) to another TRI facility (which has counted transferred waste as onsite disposal or as releases to air, land, or water).
Data source: U.S. EPA, 2007e
the de minimis exemption. For TRI reporting purposes, the
de minimis exemption allows facilities to disregard certain
minimal concentrations of non-PBT chemicals in mix-
tures or other trade name products when making threshold
determinations and release and other waste management
calculations (U.S. EPA, 2007a,c).
The 1.8 billion pounds of released PBT chemicals associ-
ated with metal mining make up 80 percent of all PBT
chemicals released between 2001 and 2005 (Exhibit 4-20,
panel B). Nearly all of these (99.9 percent) are associated
•with releases to land. Releases of PBTs by the metal min-
ing sector were 16.6 percent higher (56.7 million pounds)
in 2005 than in 2001.
Indicator Limitations
• TRI data reflect only "reported" chemicals, and not
all chemicals with the potential to affect human health
and the environment. TRI does not cover all toxic
chemicals or all industry sectors. The following are not
included in this indicator: (1) toxic chemicals that are
not on the list of approximately 650 toxic chemicals
and toxic chemical categories, (2) wastes from facili-
ties within industrial categories that are not required to
report to TRI, and (3) releases from small facilities with
fewer than 10 employees or that manufactured or pro-
cessed less than the threshold amounts of chemicals.
EPA's 2008 Report on the Environment
4-35
-------
INDICATOI
Toxic Chemicals in Production-Related Wastes Combusted
for Energy Recovery, Released, Treated, or Recycled (continued)
• TRI chemicals vary widely in toxicity, meaning that
some low-volume releases of highly toxic chemicals
might actually pose higher risks than high-volume
releases of less toxic chemicals. The release or disposal of
chemicals also does not necessarily result in the exposure
of people or ecosystems.
• Vanadium releases were measured beginning in 2001;
because the overall amounts were small relative to the
other \vastes, they are included in the 2001 to 2005 data
for non-PBTs.
National trends in toxic chemicals in wastes released to the
environment are frequently influenced by a dozen or so
large facilities in any particular reporting category. These
trends may not reflect the broader trends in the more than
23,000 smaller facilities that report to TRI each year.
• Some facilities report offsite transfers for release to other
TRI-covered facilities that report these quantities as onsite
releases. This double-counting of release quantities is taken
into account in the case of release for all sectors in total, but
not for releases within individual sectors. This may cause
some discrepancy in certain release numbers for specific
sectors when compared with release data on all sectors.
Data Sources
This indicator is based on data and information from EPA's
TRI Explorer database (U.S. EPA, 2007e), an online tool that
allows users to generate customized reports on toxic releases
reported to TRI and other online resources (U.S. EPA, 2005).
References
U.S. EPA (United States Environmental Protection
Agency). 2007a. EPA analysis of decision in Barrick
Goldstrike Mines, Inc. v. Whitman. Accessed November
28, 2007. (See also http://www.nma.org/
pdf/tri/barrick_decision040203.pdf.)
U.S. EPA. 2007b. Persistent, bioaccumulative, and toxic
(PBT) chemicals rules. Accessed November 29, 2007.
U.S. EPA. 2007c. Toxic Chemical Release Inventory
reporting forms and instructions: Revised 2006 version.
EPA/260/C-06/901.
U.S. EPA. 2007d. 2005 TRI public data release ereport.
U.S. EPA. 2007e. TRI Explorer. Accessed November 20,
2007.
U.S. EPA. 2005. 2003 TRI public data release ereport.
EPA/260/R-05/001.
Exhibit 4-20. Quantities of toxic chemicals
released in the U.S. by the metal mining sector,
as reported to EPA's Toxics Release Inventory,
1998-2005abc
A. Non-PBT chemicals (1998-2005)
1998 1999 2000 2001 2002 2003 2004 2005
Year
1.0
-S i 0.6
B. PBT chemicals (2001-2005)
0.2
0.0
0.40
U.04 y 'j>2 u'ou
2001 2002 2003 2004 2005
Year
Coverage: Production-related waste from facilities required to
report to TRI, including more than 650 chemicals and chemical
categories. Persistent, bioaccumulative, and toxic (PBT)
chemicals are presented separately because reporting thresholds
were changed partway through the period of record.
bSome waste quantities may be double-counted when waste has
been transferred from one TRI facility (which has counted waste
as offsite disposal or as other releases) to another TRI facility
(which has counted transferred waste as onsite disposal or as
releases to air, land, or water).
Percentages reported in the "What the Data Show" section are
based on the original data, which include more significant
figures than shown in this exhibit.
Data source: U.S. EPA, 2007e
U.S. EPA. 2002a. 2000 Toxics Release Inventory (TRI)
public data release report. EPA/260/R-02/003.
U.S. EPA. 2002b. 2000 Toxics Release Inventory
(TRI) public data release report, Executive Summary.
EPA/260/S-02/001
4-36
EPA's 2008 Report on the Environment
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Pesticide Residues in Food
Pesticides are substances or mixtures of substances
intended for preventing, destroying, repelling, or
mitigating plant or animal pests and may include herbi-
cides, insecticides, fungicides, and rodenticides. More than
a billion pounds of pesticides are used in the U.S. each
year to control weeds, insects, and other organisms that
threaten or undermine human activities (Aspelin, 2003).
Some of these compounds can be harmful to human health
if sufficient quantities are ingested, inhaled, or other-wise
contacted (see the Urinary Pesticide indicator, p. 5-22).
Potential health effects and primary exposure routes vary
by chemical. The most common routes of exposure for the
general population are ingestion of a treated food source
and contact with applications in or near residential sites.
Pesticides may also be harmful in the environment when
non-target organisms are exposed (U.S. EPA, 2007).
This indicator represents data from the U.S. Depart-
ment of Agriculture's Pesticide Data Program (PDF),
•which measures residue levels for hundreds of pesticides
and their metabolites in fruits, vegetables, grains, meat,
and dairy products from across the country, sampling
different combinations of commodities each year. The
analysis examines pesticides currently on the market and
also includes continued testing for some persistent and
bioaccumulative pesticides that have been banned since
the 1970s, such as aldrin/dieldrin, heptachlors, and DDT
and its metabolites. PDF data collection began in 1991 and
includes both domestic and foreign-produced commodi-
ties. Results are published in annual reports, which include
statistics on the number of pesticide residues detected, the
number of residues exceeding the tolerance established
by EPA for a given pesticide-commodity pair (Code of
Federal Regulations, Title 40, Part 180), and the num-
ber of residues detected for which no tolerance has been
established. This indicator depicts data from 1994 to 2005;
data from before 1994 are considered less reliable. Between
1994 and 2005, the number of food samples analyzed per
year ranged from 5,771 (1996) to 13,693 (2005), with a
general increase over time.
What the Data Show
The percent of samples with no detectable pesticide resi-
dues generally increased during the period from 1994 to
2002 (Exhibit 4-21). Samples \vith no detects accounted for
38.5 percent of samples analyzed in 1994 and rose to 57.9
percent of samples in 2002. Data for 2003 and thereafter
cannot be compared directly to the previous years' data due
to a change in the way that detects are counted. Data for
2004 and 2005 show a lower percentage of samples with no
detects than 2003 data, going from 53.9 percent of samples
in 2003 to 29.5 percent in 2004 and 33.7 percent in 2005.
The largest jump in detects in the 2003-2004 time frame
•was in those samples with detection of one pesticide or
Exhibit 4-21. Pesticide detections in food in the
U.S., 1994-2005ab
100
60
40
20
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Coverage: Based on a survey of fruits,
vegetables, grains, meat, and dairy products
across the U.S., with different combinations
of commodities sampled in different years.
Samples were analyzed for more than 290
pesticides and their metabolites.
"Data from 2003 to 2005 are not comparable
to prior years due to a difference in how
detects were counted. Prior to 2003, each
compound detected was counted as a
separate "residue." Beginning in 2003, parent
compounds and their metabolites were combined to report the
number of "pesticides." For example, a sample with positive
detections for endosulfan I, endosulfan II, and endosulfan sulfate
would have been counted as three residues in 2002. In 2003, this
sample would have been counted as one pesticide detection.
Data source: USDA Agricultural Marketing Service, 1996-2006a,b
Number of
residues
detected:
DO
D1
D2
D3
n 4 or more
metabolite. These trends in number of detections have
occurred at the same time that analytical limits of detec-
tion for various compounds have been decreasing, allowing
the instruments to pick up ever smaller concentrations.
Exhibit 4-22 illustrates the percentage of samples in
•which at least one pesticide residue was detected at a
concentration exceeding the tolerance established by EPA
for a given pesticide-commodity pair. The percentage of
samples exceeding EPA tolerance values increased from
0.05 percent in 1994 to 0.31 percent in 2003. Compared to
2003, the last 2 years of data show a drop in exceedances,
with 0.17 percent in 2004 and 0.18 percent in 2005.
Indicator Limitations
As Exhibit 4-21 explains, pesticide detection data from
2002 and earlier cannot be compared directly with data
gathered after 2002. (Before 2003, each compound
detected was counted separately; beginning in 2003,
measurement of a parent compound and/or any of its
metabolites was counted as a single detect.)
EPA's 2008 Report on the Environment
4-37
-------
INDICATOR
Pesticide Residues in Food (continued)
Exhibit 4-22. Pesticides exceeding EPA
tolerance levels in food in the U.S., 1994-20053
0.35
0.30
CD —
0.20
E S 0.15
"1
o £ 0.10
£2 0.05
0.00
'94 '95 '96 '97
'99 '00 '01 '02 '03 '04 '05
Year
Coverage: Based on a survey of fruits, vegetables, grains, meat,
and dairy products across the U.S., with different combinations of
commodities sampled in different years. Samples were analyzed
for more than 290 pesticides and their metabolites.
Data source: USDA Agricultural Marketing Service, 1996-2006a,b
The PDF does not sample all commodities over all
years, so some gaps in coverage exist. Differences in
the percent of detections for any given pesticide class
might not be due to an increase (or decrease) in the
predominance of detectable residues. Instead, these dif-
ferences might simply reflect the changing nature and
identity of the commodities selected for inclusion in any
given time frame.
• The indicator measures pesticide residue related to di-
etary intake, which does not directly correlate to toxico-
logical effects in humans or effects on the environment.
Data Sources
Data for this indicator were obtained from a series of annual
summary reports published by the PDF (USDA Agricultural
Marketing Service, 1996-2006). These reports are all avail-
able from http://www.ams.usda.gov/science/pdp/. The Food
and Drug Administration also collects data (not reported
here) on pesticide residues in cooked food that may be a
source of chemicals in human diets. These data are available
at http://www.cfsan.fda.gov/~dms/pesrpts.html.
References
Aspelin, A.L. 2003. Pesticide usage in the United States:
Trends during the 20th century. Raleigh, NC: Center for
Integrated Pest Management, North Carolina State Uni-
versity.
USDA Agricultural Marketing Service. 2006a. Pesticide
Data Program: Annual summary, calendar year 2005.
USDA Agricultural Marketing Service. 2006b. Pesticide
Data Program: Annual summary, calendar year 2004.
USDA Agricultural Marketing Service. 2005. Pesticide
Data Program: Annual summary, calendar year 2003.
USDA Agricultural Marketing Service. 2004. Pesticide
Data Program: Annual summary, calendar year 2002.
USDA Agricultural Marketing Service. 2003. Pesticide
Data Program: Annual summary, calendar year 2001.
USDA Agricultural Marketing Service. 2002. Pesticide
Data Program: Annual summary, calendar year 2000.
USDA Agricultural Marketing Service. 2001. Pesticide
Data Program: Annual summary, calendar year 1999.
USDA Agricultural Marketing Service. 2000. Pesticide
Data Program: Annual summary, calendar year 1998.
USDA Agricultural Marketing Service. 1999. Pesticide
Data Program: Annual summary, calendar year 1997.
USDA Agricultural Marketing Service. 1998. Pesticide
Data Program: Annual summary, calendar year 1996.
USDA Agricultural Marketing Service. 1997. Pesticide
Data Program: Annual summary, calendar year 1995.
USDA Agricultural Marketing Service. 1996. Pesticide
Data Program: Annual summary, calendar year 1994.
U.S. EPA. 2007. Data requirements for pesticide registra-
tion. Accessed November 28, 2007.
4-38
EPA's 2008 Report on the Environment
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Reported Pesticide Incidents
Although pesticides play a role in protecting human
health, food, and crops, they pose a risk of poison-
ing when not used and/or stored properly. The American
Association of Poison Control Centers (AAPCC) collects
statistics on poisonings and represents the single largest
source of information on acute health effects of pesticides
resulting in symptoms and requiring health care (Calvert et
al., 2001). The data include incidents related to individual
pesticides and to mixtures of products (about 8 percent of
reports). The data also include intentional exposures (suicide
attempts and malicious use), which account for less than 3
percent of reports. The AAPCC uses the Toxic Exposure
Surveillance System (TESS) to collect information on all
reported incidents.
This indicator is based on data from TESS-published
reports for the years 1986 through 2005. During this
period, at least 50 percent of the U.S. population was
covered by poison control centers (PCCs) reporting to the
national database. Annual reports of incidents were divided
by the percent of U.S. population served to estimate the
total incidents nation-wide, and divided by the total
U.S. population to develop the incidence rate. Only calls
•with known outcomes are reported here; this may intro-
duce some bias, because the percent of all reported pesti-
cide incidents with a known outcome declined from 71
percent in 1986-1988 to just 41 percent in 2004-2005. The
2004-2005 data are averaged over 2 years; all other data
are grouped into 3-year periods and presented as average
annual rates to facilitate identification of trends.
What the Data Show
Between the 1986-1988 and 2001-2003 periods, there
•was an overall 40 percent decline in reported pesticide
incidents in the U.S. In 2004-2005, however, there was a
slight rise compared to 2001-2003, primarily in the "other
insecticides" and "all other pesticides" categories (Exhibit
4-23). The single largest decline occurred for the category
of organophosphate (OP) insecticides, which saw nearly a
79 percent drop in reported incidents between 1986-1988
and 2004-2005. Part of the decline in reported OP-related
incidents may be due to the substitution of other, less toxic
insecticides for some of the OPs over time.
Indicator Limitations
Misclassification of incidents may occur when incidents
reported over the phone are not verified by laboratory
tests. For example, a child found holding a pesticide
container may not have actually been exposed, but if a
call is received by a PCC poison specialist who deter-
mines that the reported symptoms were consistent with
the toxicology, dose, and timing of the incident, the
call \vill be registered as an incident. About 13 percent
of calls to PCCs arise from health care professionals, but
Exhibit 4-23. Reported pesticide incidents per
million U.S. population by type of pesticide,
1986-2005ab
^•g 140
CD ^
1 8 120
.E |
"S re 100
II
Q- O on
CD o. °U
°l 60
CD • —
I S 40
20
-
1986-
1989-
1991
1992-
1994
1995-
1997
1998-
2000
2001-
2003
2004-
2005
Reporting period
aThis indicator tracks pesticide incidents
reported to poison control centers
(PCCs) that report to the AAPCC
national database. The rate of reported
incidents is calculated based on the
population served by these PCCs.
bThe 2004-2005 data are averaged
over 2 years. All other data are averaged
over 3-year intervals.
Data source: Lai et al., 2006; Litovitz et
al., 1987-2002; Watson etal., 2003-2005
n Disinfectants
D Organophosphates
D Other insecticides
D Herbicides
D Fungicides
D Rodenticides
D All other pesticides
the majority are calls made by victims or their relatives
or caretakers. Although some misclassification can be
expected to occur, it is assumed to be non-differential
among the different types of pesticides.
Only calls with known outcomes are reported in this
indicator. This may introduce some bias, because the
percent of all reported pesticide incidents with known
outcomes declined from 71 percent in 1986-1988 to just
41 percent in 2004-2005.
• The data collection process is standardized for PCCs,
but is a passive system. Under-reporting of incidents is a
serious shortcoming. Studies show that medical facilities
generally report between 24 and 33 percent of incidents
from all substances to PCCs (Chafee-Bahamon et al.,
1983; Harchelroad et al., 1990; Veltri et al., 1987).
Data are collected by multiple poison centers, with
follow-up likely performed in different ways.
Data Sources
This indicator is based on summary data from annual
reports published by the TESS (Litovitz et al., 1987-2002;
Watson et al., 2003-2005; Lai et al., 2006) (available from
http://www.aapcc.org/poisonl.htm). Annual data from
EPA's 2008 Report on the Environment
4-39
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INDICATOR
Reported Pesticide Incidents (continued)
these reports were grouped into 3-year periods, with the
exception of 2004-2005 where only 2 years of data were
grouped together, and incidence rates were calculated from
the population served by participating PCCs; population
figures can also be found in the annual reports. Only sum-
mary data are publicly available; raw data from individual
cases are considered confidential.
References
Calvert, G.M., M. Barnett, J.M. Blondell, L.N. Mehler,
and W.T. Sanderson. 2001. Surveillance of pesticide-related
illness and injury in humans. In: Krieger, R., ed. Hand-
book of pesticide toxicology. Second edition. San Diego,
CA: Academic Press, pp. 603-641.
Chafee-Bahamon, C., D.L. Caplan, and F.H. Lovejoy.
1983. Patterns in hospital's use of a regional poison infor-
mation center. Am. J. Public Health 73:396-400.
Harchelroad, F., R.F. Clark, B. Dean, andE.P. Krenzelok.
1990. Treated vs. reported toxic exposures: Discrepancies
between a poison control center and a member hospital.
Vet. Hum. Toxicol. 32:156-159.
Lai, M.W., W. Klein-Schwartz, G.C. Rodgers, J.Y. Abrams,
D.A. Haber, A.C. Bronstem, and K.M. Wruk. 2006. 2005
annual report of the American Association of Poison Con-
trol Centers Toxic Exposure Surveillance System. Clin.
Toxicol. 44:803-932.
Litovitz, T.L., W. Klein-Schwartz, G.C. Rodgers, Jr,
DJ. Cobaugh, J. YoumssJ.C. Omslaer, M.E. May, A.D.
Woolf, and B.E. Benson. 2002. 2001 annual report of
the American Association of Poison Control Centers
Toxic Exposure Surveillance System. Am. J. Emerg. Med.
20(5):391-452.
Litovitz, T.L., W. Klein-Schwartz, S. White, DJ.
Cobaugh, J. Youniss,J.C. Omslaer, A. Drab, and B.E.
Benson. 2001. 2000 annual report of the American
Association of Poison Control Centers Toxic Exposure
Surveillance System. Am. J. Emerg. Med. 19(5):337-395.
Litovitz, T.L., W. Klein-Schwartz, S. White, DJ. Cobaugh,
J. Youmss, A. Drab, and B.E. Benson. 2000. 1999 annual
report of the American Association of Poison Control Centers
Toxic Exposure Surveillance System. Am. J. Emerg. Med.
18(5):517-571.
Litovitz, T.L., W. Klein-Schwartz, E.M. Caravati, J. Youniss,
B. Crouch, and S. Lee. 1999. 1998 annual report of the
American Association of Poison Control Centers Toxic Expo-
sure Surveillance System. Am. J. Emerg. Med. 17(5):435-487.
Litovitz, T.L., W. Klein-Schwartz, K.S. Dyer, M. Shan-
non, S. Lee, and M. Powers. 1998. 1997 annual report
of the American Association of Poison Control Centers
Toxic Exposure Surveillance System. Am. J. Emerg. Med.
16(5):443-497.
Litovitz, T.L., M. Smilkstem, L. Felberg, W. Klein-
Schwartz, R. Berlin, andJ.L. Morgan. 1997. 1996 annual
report of the American Association of Poison Control
Centers Toxic Exposure Surveillance System. Am. J.
Emerg. Med. 15(5):447-500.
Litovitz, T.L., L. Felberg, W. Klein-Schwartz, and S.
White. 1996. 1995 annual report of the American Associa-
tion of Poison Control Centers Toxic Exposure Surveil-
lance System. Am. J. Emerg. Med. 14(5):487-537.
Litovitz, T.L., L. Felberg, R.A Soloway, M. Ford, and R.
Geller. 1995. 1994 annual report of the American Associa-
tion of Poison Control Centers Toxic Exposure Surveillance
System. Am. J. Emerg. Med. 13(5):551-597.
Litovitz, T.L., L.R. Clark, and R.A Soloway. 1994. 1993
annual report of the American Association of Poison Con-
trol Centers Toxic Exposure Surveillance System. Am. J.
Emerg. Med. 12(5):546-584.
Litovitz, T.L., K.C. Holm, C. Clancy, B.E Schmitz,
L.R. Clark, and G.M. Oderda. 1993. 1992 annual report
of the American Association of Poison Control Centers
Toxic Exposure Surveillance System. Am. J. Emerg. Med.
ll(5):494-555.
Litovitz, T.L., K.C. Holm, K.M. Bailey, and B.E Schmitz.
1992. 1991 annual report of the American Association of
Poison Control Centers Toxic Exposure Surveillance Sys-
tem. Am. J. Emerg. Med. 10(5):452-504.
Litovitz, T.L., K.M. Bailey, B.F. Schmitz, K.C. Holm,
and W. Klein-Schwartz. 1991. 1990 annual report of the
American Association of Poison Control Centers Toxic
Exposure Surveillance System. Am. J. Emerg. Med.
9(5):461-509.
Litovitz, T.L., B.F. Schmitz, and K.M. Bailey. 1990. 1989
annual report of the American Association of Poison Con-
trol Centers Toxic Exposure Surveillance System. Am. J.
Emerg. Med. 8(5):394-442.
4-40
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INDICATOI
Reported Pesticide Incidents (continued)
Litovitz, T.L., B.F. Schmitz, and K.C. Holm. 1989. 1988
annual report of the American Association of Poison Con-
trol Centers Toxic Exposure Surveillance System. Am. J.
Emerg. Med. 7(5):495-545.
Litovitz, T.L., B.F. Schmitz, N. Matyunas, and T.G. Mar-
tin. 1988. 1987 annual report of the American Association
of Poison Control Centers Toxic Exposure Surveillance
System. Am. J. Emerg. Med. 6(5):479-515.
Litovitz, T.L., T.G. Martin, andB. Schmitz. 1987. 1986
annual report of the American Association of Poison Con-
trol Centers Toxic Exposure Surveillance System. Am. J.
Emerg. Med. 5(5):405-445.
Veltri, J.C., N.E. McElwee, and M.C. Schumacher. 1987.
Interpretation and uses of data collected in poison control
centers in the United States. Med. Toxicol. 2:389-397.
Watson, W.A., T.L. Litovitz, G.C. Rodgers, W. Klein-
Schwartz, N. Reid, J. Youniss, A. Flanagan, and K.M.
Wruk. 2005. 2004 Annual Report of the American Asso-
ciation of Poison Control Centers Toxic Exposure Surveil-
lance System. Am. J. Emerg. Med. 23:589-666.
Watson, W.A., T.L. Litovitz, W. Klein-Schwartz, G.C.
Rodgers, Jr., J. Youniss, N. Reid, W.G. Rouse, RS. Rem-
bert, and D. Borys. 2004. 2003 annual report of the Ameri-
can Association of Poison Control Centers Toxic Exposure
Surveillance System. Am. J. Emerg. Med. 22(5):335-404.
Watson, W.A., T.L. Litovitz, G.C. Rodgers, Jr., W. Klein-
Schwartz,}. Youniss, S.R. Rose, D. Borys, andM.E. May.
2003. 2002 annual report of the American Association of
Poison Control Centers Toxic Exposure Surveillance Sys-
tem. Am. J. Emerg. Med. 21(5):353-421.
4.5.3 Discussion
What These Indicators Say About Trends in
Chemicals Used on the Land and Their Effects
on Human Health and the Environment
These indicators provide information on aspects of chemical
use and effects. Data are presented on the amounts and types
of chemical usage for two large sectors of the U.S. economy—
agriculture and manufacturing. The disposition of pesticides
in food and the number of reported pesticide incidents are
examined. Two indicators describe stressors to the environ-
ment from chemical usage.
The amount of chemicals deliberately applied to agricultural
land as commercial fertilizer has increased over the last 40
years (Agricultural Fertilizer indicator, p. 4-30). Per acre total
fertilizer use has nearly tripled since 1960, with peak usage
occurring in 2004. Total nitrogen use has more than quadru-
pled over the same period. While fertilizers themselves are not
inherently harmful, when applied improperly or in quanti-
ties above the level taken up by crops, streamside vegetation,
or soil biota, they have the potential to contaminate ground
•water and surface water in agricultural -watersheds and estuar-
ies. Fertilizer usage in recent years, for major crops, appears
concentrated in the states surrounding the Mississippi River.
The Toxics Release Inventory (TRI) data (Toxic Chemicals in
Wastes indicator, p. 4-33) show a small but steady decline in the
quantities of TRI chemicals released to all media between 1998
and 2005, \vith the exception of offsite releases (persistent, bio-
accumulative, and toxic or other-wise), -which increased slightly.
Residues of potentially harmful substances used in food
production, such as some pesticides, are assessed under food
protection programs. While national-level indicators on the
use and application of pesticides and pesticide loads in soil are
lacking, the Pesticide Residues in Food indicator (p. 4-37) is
an indirect measure of ambient conditions, providing insight
into potential exposures from the most -widely used pesticide
products on the market. The indicator shows that between
2003 and 2005 (after a change in sampling technique), pesti-
cide residues -were detected in 46 percent of the food com-
modities tested in 2003 and in 66 to 71 percent of the food
commodities tested in 2004 and 2005. Currently available
technology used in the U.S. Department of Agriculture's Pes-
ticide Data Program sampling can detect pesticide residues at
concentrations that are orders of magnitude lower than those
determined to have potential human health effects. Therefore,
the number of pesticide detections that exceed federally estab-
lished tolerance levels is perhaps more relevant. Results over
the years suggest less than 1 percent of commodities tested
•were above tolerance levels.
Similarly, the Pesticide Incidents indicator (p. 4-39) provides
information on the potential for human exposure to toxic
substances through misuse. Reported incidents of pesticide
exposure, -which represent accidental exposure to a pesticide
that is readily available to the public, declined between 1986
and 2003, then rose slightly in 2004-2005. The largest decline
occurred in organophosphate compounds, a group of insecti-
cides that are acutely toxic to humans (and other vertebrates)
but do not accumulate in the environment, unlike other toxic
materials (or compounds containing them) such as chromium,
arsenic, and heavy metals.
EPA's 2008 Report on the Environment
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Limitations, Gaps, and Challenges
While chemicals in soil or on plants may be an initial path-way
into the environment, it is the movement and concentration
of chemicals through the food chain that are often of greatest
concern, as well as exposures from other media such as con-
taminated water or air. The indicators provide information on
a relatively small universe of toxic chemicals and only limited
information on the potential exposures humans may experi-
ence as a consequence of chemical use.
Fertilizer use in agriculture has been identified as one of the
principal uses of chemicals responsible for nutrient loading
into non-targeted water bodies and for nonpoint source load-
ing of nutrients within agricultural -watersheds.26 Actual fertil-
izer use data are not available nationally. The Agricultural
Fertilizer indicator (p. 4-30) is supported by sales data that
do not consider mitigating factors (e.g., slow-release formula-
tions) or agricultural practices that reduce runoff. The cost of
fertilizer accounts for a relatively high percentage of agricul-
tural costs, so it is generally assumed that purchased products
eventually are applied in agricultural operations. Agricultural
sources of fertilizer, however, are only estimated to be 85
percent of all sources, -with the remaining being primarily
professional lawn care, consumer retail, and golf courses. The
usage patterns associated -with these nonagricultural sources
are unknown. Additionally, the urban and suburban -water-
sheds, -where these non-tracked uses occur, are also locations
•where nutrient runoff may result from other sources such as
turf runoff, septic systems, and sewage treatment plants.
The indicators do not provide information related to the land
application of sludges27 that may contain toxic metals and
other persistent bioaccumulative substances. Sludges may be
applied as fertilizer on agricultural or forest land in accordance
•with EPA requirements, but the implications for -wildlife,
aquatic organisms, and movement through the food chain are
unknown. Additionally, the indicators reported provide only
limited information on the potential exposures that target
organisms other than humans may experience as a conse-
quence of chemical use.
TRI data include information on a range of chemical cat-
egories such as arsenic, cyanide, dioxin, lead, mercury, and
nitrate compounds, but do not reflect a comprehensive total
of toxic releases nation-wide. They do not include all toxic
chemicals -with the potential to affect human health and the
environment, nor do they include all sources of potential
releases. Facilities report release and other -waste manage-
ment data using various techniques, -which include estima-
tions based on emission factors, mass balancing approaches,
engineering calculations, and actual monitoring. Estimation
techniques and factors considered may vary -widely, making
it difficult to ensure the accuracy of reporting. TRJ data only
represent a portion of the chemical life cycle (e.g., -wastes as a
result of production) and do not take into account amounts of
Howarth, R.W., D.Walker, and A. Sharpley. 2002. Sources of nitrogen pollu-
tion to coastal waters of the United States. Estuaries 25:656-676.
chemicals incorporated into industrial and/or consumer prod-
ucts that also have the potential to affect the environment and
human health -when they are used, discarded, or recycled.
There is no existing reporting system that provides informa-
tion on the volume, distribution, and extent of pesticide use
in the U.S. Estimates are developed based on information
available through a variety of reports from multiple govern-
mental and non-governmental entities on pesticide sales, crop
profiles, and expert surveys. The Pesticide Residues in Food
indicator (p. 4-37) provides information on one aspect of the
potential for human exposure from pesticides (dietary intake
from the commercial food supply), but does not provide a
complete picture of all the -ways in -which humans can be
exposed to pesticides, -which include contaminated drinking
•water, pesticide drift, and dermal contact.
4.6 What Are the Trends
in Contaminated Land
•ffects on
Human Health and the
Environment?
4.6.1 Introduction
There are many settings for contaminated lands, ranging from
abandoned buildings in inner cities to large areas contami-
nated \vith toxic materials from past industrial or mining
activities. Contaminated lands include sites contaminated
by improper handling or disposal of toxic and hazardous
materials and wastes, sites where toxic materials may have
been deposited as a result of wind or flood, and sites where
improper handling or accidents resulted in release of toxic or
hazardous materials that are not wastes.
Land contamination can result from a variety of intended,
accidental, or naturally occurring activities and events such
as manufacturing, mineral extraction, abandonment of
mines, national defense, waste disposal, accidental spills,
illegal dumping, leaking underground storage tanks, hurri-
canes, floods, pesticide use, and fertilizer application. Sites are
categorized in a variety of ways, often based on the level and
type of contamination and the regulations under which they
are monitored and cleaned up. Box 4-1 provides an overview
of the common types of contaminated sites. With the excep-
tion of accidental spills and contamination that result from
naturally occurring and other unanticipated events, most land
contamination is the result of historical activities that are no
longer practiced. Hazardous material and waste management
and disposal are now highly regulated.
Sludges are the nutrient-rich organic materials resulting from sewage and
wastewater treatment processes. Sludges contain many of the nutrients required
for improved plant growth (nitrogen, phosphorus, and potassium) and other
organic matter that can improve overall soil condition and increase productivity.
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EPA's 2008 Report on the Environment
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Contaminated soils can leach toxic chemicals into nearby
ground or surface waters, where these materials can be taken
up by plants and animals, contaminate a human drinking water
supply, or volatilize and contaminate the indoor air in overly-
ing buildings. In dry areas, contamination in soil can be further
distributed through wind-borne dusts. Once soil contamina-
tion migrates to waterways, it may also accumulate in sedi-
ments, which can be very difficult to remediate and may affect
local ecosystems and human health. Humans can be harmed
by contact with toxic and hazardous materials on a contami-
nated site via exposure to contaminated land, air, surface water,
and ground water. When contaminated lands are not properly
managed, humans and wildlife can be exposed to contaminants
through inhalation, ingestion, or dermal contact. The risks of
human exposure are site-specific and difficult to generalize at
the national level. Potential effects may be acute or chronic.
Some contaminated sites pose little risk to human health and
the environment, because the level of contamination is low
and the chance of exposure to toxic or hazardous contami-
nants is also low. Other contaminated sites are of greater con-
cern because of the chemicals that may be present and their
propensity to persist in or move through the environment,
exposing humans or the environment to hazards. These sites
must be carefully managed through containment or cleanup
to prevent hazardous materials from causing harm to humans,
•wildlife, or ecological systems, both on- and offsite.
Nationally, there are thousands of contaminated sites of vary-
ing size and significance. Many sites, particularly the largest
Box 4-1. Categorizing Contaminated Lands
Superfund National Priorities List sites: These sites
are seriously contaminated and include industrial facilities,
•waste management sites, mining and sediment sites, and
federal facilities such as abandoned mines; nuclear, biologi-
cal, chemical, and traditional weapons productions plants;
and military base industrial sites (e.g., used for aircraft and
naval ship maintenance).
Resource Conservation and Recovery Act (RCRA)
Cleanup Baseline facilities: The RCRA Cleanup Base-
line is a priority subset of a broader universe of facilities
that are subject to cleanup under RCRA due to past or
current treatment, storage, or disposal of hazardous wastes
and have historical releases of contamination.
Underground storage tanks/leaking underground
storage tanks: Businesses, industrial operations, gas sta-
tions, and various institutions store petroleum and hazardous
substances in large underground storage tanks that may fail
due to faulty materials, installation, operating procedures,
or maintenance systems, causing contamination of soil and
ground water.
Accidental spill sites: Each year, thousands of oil, gas,
and chemical spills occur on land and in water from a
variety of types of incidents, including transportation (e.g.,
rail, barges, tankers, pipeline) and facility releases.
Sites contaminated by natural disasters or terror-
ist activities: Disasters of any sort, naturally occurring or
caused by humans, have the potential to contaminate lands
and cause problems at already-contaminated sites.
Land contaminated with radioactive and other
hazardous materials: Many sites spanning a large area
of land in the U.S. are contaminated with radioactive and
other hazardous materials as a result of activities associated
•with nuclear weapons production, testing, and research.
Brownfields: Brownfields are real property where expan-
sion, redevelopment, or reuse may be complicated by the
presence or potential presence of a hazardous substance,
pollutant, or contaminant. Brownfields are often found in
and around economically depressed neighborhoods.
Military bases and defense sites: Some of the millions
of acres of land used by the Department of Defense are
contaminated from releases of hazardous substances and
pollutants; discarded munitions, munitions constituents,
and unexploded ordnance; and building demolition and
debris.
Low-level area-wide contamination: Some soil
contamination problems involve low to moderate levels
of contamination that encompass large geographic areas
ranging in size from several hundred acres to many square
miles. Low-level, area-wide contamination can occur from
emissions related to past industrial operations (e.g., smelt-
ers), -widespread agricultural pesticide applications, com-
bustion of gasoline, and deterioration of lead-based paint.
Past waste management sites and illegal dumping
sites: Prior to the 1970s, solid waste was typically placed
in unlined landfills that were not adequately designed to
prevent adverse environmental impacts to ground water
or surface water. Separately, illegal dumping of materials
such as construction waste, abandoned automobiles, appli-
ances, household waste, and medical waste, has occurred
for decades and still occurs because of convenience and the
cost of legal disposal.
Abandoned and inactive mine lands: Abandoned and
inactive mines may not have been properly cleaned up, and
may have features ranging from exploration holes to full-
blown, large-scale mine openings, pits, waste dumps, and
processing facilities.
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4-43
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and most severely contaminated, are tracked at the national
level, but many others are tracked only at state or local levels.
The number and status of contaminated sites changes fre-
quently as sites are newly contaminated (e.g., via spills or hur-
ricanes), discovered, documented, and cleaned up.
4.6.2 ROE Indicators
The ROE indicators for this question focus on the trends in
reducing potential threats to human health associated with
site contamination at some lands contaminated by a variety of
industrial and other activities and from current and past waste
management activities (Table 4-6). The indicators address sites
on the Superfund National Priorities List and facilities on the
Resource Conservation and Recovery Act Cleanup Baseline
•where human exposure to contamination and migration of
contaminated ground water have been documented to be
\vithin acceptable established health-based levels.
Trends in the spread of contaminated ground water and
potential human exposure to contaminants in excess of
health-based standards are assessed through site-specific
monitoring and modeling data collected by site personnel.
Site data and conditions are generally reviewed and confirmed
by federal and/or state program managers annually, or more
frequently if site conditions warrant.
Table 4-6. ROE Indicators of Trends in Contaminated Land and Their
Effects on Human Health and the Environment
National Indicators
Current Human Exposures Under Control at High-Priority Cleanup Sites
Migration of Contaminated Ground Water Under Control at High-Priority
Cleanup Sites
Section
4.6.2
4.6.2
4-44
4-47
INDICATOI
Current Human Exposures Under Control at High-Priority
Cleanup Sites
The EPA Superfund and Resource Conservation and
Recovery Act (RCRA) Programs conduct a number
of activities to address the nation's most severely contami-
nated lands. The Programs investigate and collect data on
potentially contaminated sites to determine whether they
are contaminated and require cleanup. When a potentially
hazardous waste site is reported to EPA, trained inspectors
determine whether the site presents a hazard to human
health and the environment. Sites that pose the greatest
threat are placed on the Superfund National Priorities List
(NPL) or RCRA Cleanup Baseline. For RCRA, "sites"
are more commonly referred to as RCRA Corrective
Action Facilities.
One of the priorities for both the NPL and RCRA
Cleanup Baseline sites is safeguarding against human
exposures to site contamination. EPA and state officials
determine whether there is a reasonable expectation that
humans are exposed to site contamination and if interim
actions are needed to reduce or eliminate all current human
exposure in excess of health-based standards. Such activi-
ties may include removing and/or isolating contaminated
media, providing alternative water supplies, and restricting
access or other land use controls. Exposure at levels below
the standards is considered protective (i.e., under control).
Although these standards may vary from state to state, EPA
believes that they fall within an acceptable range for gaug-
ing whether human health is protected (U.S. EPA, 2005b).
Determinations of human exposure at levels of concern are
based on site-specific characterization information and mon-
itoring data (usually many analytical samples) pertaining to
relevant environmental media (e.g., soil, indoor air, outdoor
air, ground water, and surface water), current human activ-
ity patterns, and actions taken to prevent human exposure.
All potential exposure routes are assessed, including inhala-
tion, dermal contact, and ingestion of the contaminated
media or food affected by contaminated media (U.S. EPA,
1999, 2005b).
This indicator describes the numbers of NPL Indicator
Baseline sites and RCRA Cleanup Baseline sites for which
government officials have determined that (1) humans are
not exposed to contamination in excess of health-based
standards (i.e., exposure is under control); (2) humans are
reasonably expected to be exposed to contamination in
excess of health-based standards; or (3) insufficient infor-
mation exists to make a finding of exposure to contamina-
tion in excess of health-based standards. The intention of
the indicator is not to capture an "action" or "administra-
tive determination" on the part of EPA, but to characterize
4-44
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Current Human Exposures Under Control at High-Priority
Cleanup Sites (continued)
environmental conditions relevant to the risk to human
health from contaminants at RCRA Cleanup Baseline and
NPL Indicator Baseline sites.
What the Data Show
In 2007, there were 1,968 sites on the RCRA Cleanup
Baseline (U.S. EPA, 2007a). Of these, the percentage of
sites where human exposure to contamination was under
control increased from 37 percent (642 sites out of 1,714) in
fiscal year (FY) 2000 to 93 percent (1,830 sites out of 1,968)
in FY 2007 (Exhibit 4-24, panel A). This increase repre-
sents a combination of sites where mitigation has prevented
exposure to contaminants and sites where there are sufficient
data to show that exposure to contaminated media was not
a problem, regardless of mitigation. The percentage of sites
•where officials had reasonable expectations that humans
•were exposed to contamination in excess of health-based
standards has decreased from 13 percent (225 sites out of
1,714) in FY 2000 to less than 1 percent (15 sites out of
1,968) in FY 2007.
As of September 2007, there were 1,554 sites on the NPL
that \vere categorized as "Final" or "Deleted" (U.S. EPA,
2007b,c). These are referred to as the Superfund NPL Indi-
cator Baseline. The Superfund NPL Indicator Baseline sites
•where human exposure to contamination was under con-
trol increased as a percentage of the total: 80 percent (1,199
of 1,494 sites) in 2002 and 82 percent (1,282 of 1,554 sites)
in 2007 (Exhibit 4-24, panel B). As of the end of FY 2007,
officials determined that there were reasonable expecta-
tions that humans were exposed to contamination in excess
of health-based standards at 7 percent (109 out of 1,554)
of the NPL Indicator Baseline sites. This is a decrease
from 2002, when the percentage was 8 percent (120 out
of 1,494). In 2007, there was insufficient information to
confirm whether humans were exposed to contamination
in excess of health-based standards at 10 percent (163 out of
1,554) of the sites.
Indicator Limitations
• The NPL does not represent all of the contaminated or
potentially contaminated sites listed in the Comprehensive
Environmental Response, Compensation, and Liability
Information System (CERCLIS) database, which contains
information on thousands of hazardous waste sites, poten-
tial hazardous waste sites, and remedial activities across the
nation. A small percentage (less than 1 percent) of the total
number of final and deleted NPL sites are excluded from
the Indicator Baseline for reasons of consistency.
Exhibit 4-24. Status of current human
exposures under control at high-priority cleanup
sites in the U.S., fiscal years 2000-2007
A. RCRA Cleanup Baseline sites (2000-2007)3
2,000
1,500
CO
CD
'co
° 1,000
-------
INDICATOI
Current Human Exposures Under Control at High-Priority
Cleanup Sites (continued)
• The indicator results are presented for the 1,714
RCRA Cleanup Baseline sites tracked from 2000 to
2005 and the 1,968 sites tracked in 2006 and 2007, and
not the entire group of approximately 3,476 hazard-
ous waste management facilities currently believed to
be subject to RCRA Corrective Action requirements
(e.g., initial assessments and if needed more thorough
investigations and cleanups) (see http://www. epa.gov/
epaoswer/hazwaste/ca/lists/2020scc.pdf).
• The indicator does not typically make measurements
of exposure biomarkers among potentially exposed
individuals at the NPL Indicator Baseline or RCRA
Cleanup Baseline sites, but relies on environmental
measures at or near the point of exposure and activities
that should prevent exposure to contaminants.
• Concentrations of toxic and hazardous contaminants
that must not be exceeded to designate a site as hav-
ing/not having human exposures to contamination in
excess of health-based standards vary from state to state,
although they fall within a range determined to be ac-
ceptable to EPA (U.S. EPA, 2005a,b).
The indicator is based on certification by a responsible
official that the criteria necessary to designate a site as
having/not having human exposures to contamination
in excess of health-based standards have been met (U.S.
EPA, 1999, 2005a,b). The trend in the number of sites
may be underestimated to the extent that certification
lags behind the potential human exposure to contami-
nation or certification is delayed due to insufficient or
outdated information.
• This approach may not take into account certain risks
(e.g., endocrine disrupters) where specific risk levels
(e.g., to human health) may not have been established.
Some new sites (e.g., those created with the "reportable
quantity" spill response program) as well as other known
sites (e.g., spills) are not included in this indicator.
Data Sources
Data for this indicator were provided by EPA's Office of
Solid Waste and Emergency Response (OSWER). A list
showing the current status of every RCRA baseline site is
published online (U.S. EPA, 2007a). A discussion of NPL
indicators is available (U.S. EPA, 2005a); information on
the current status of any individual NPL site can be queried
using EPA's CERCLIS database (U.S. EPA, 2006) (http://
cfpub.epa.gov/supercpad/cursites/srchsites.cfm). Data for
previous years are not publicly accessible, however, and must
be requested from OSWER.
References
U.S. EPA (United States Environmental Protection Agency).
2007a. Facilities on the RCRA 2008 GPRA corrective
action baseline. Report generated 10/25/2007.
U.S. EPA. 2007b. Final NPL sites—by site name (as of
October 26, 2007). Accessed November 25, 2007.
U.S. EPA. 2007c. National Priorities List (NPL) advanced
query form. NPL status: Deleted from the final NPL.
Accessed November 25, 2007.
U.S. EPA. 2006. CERCLIS database. Accessed Septem-
ber 14, 2006.
U.S. EPA. 2005a. Draft Superfund environmental
indicators guidance manual: Long-term human health
revisions.
U.S. EPA. 2005b. Frequently asked questions—human
exposure under control (HE) and migration of contaminated
ground water under control (GM) environmental indicators.
U.S. EPA. 1999. Interim-final guidance for RCRA corrective
action environmental indicators,
4-46
EPA's 2008 Report on the Environment
-------
Migration of Contaminated Ground Water Under Control at
High-Priority Cleanup Sites
The EPA Superfund and Resource Conservation and
Recovery Act (RCRA) Programs conduct a number
of activities to address the nation's most severely contami-
nated lands. The Programs investigate and collect data on
potentially contaminated sites to determine whether they
are contaminated and require cleanup. When a potentially
hazardous waste site is reported to EPA, trained inspec-
tors determine whether the site presents a hazard to human
health and the environment. Sites that pose the greatest
threat are placed on the National Priorities List (NPL) or
RCRA Cleanup Baseline.
One of the priorities for both the NPL and RCRA
Cleanup Baseline sites is preventing the continued spread
of contaminated ground water, often referred to as
"plumes" of contaminated ground water. Protecting the
ground water is especially important in areas where it is
the primary source for drinking water and irrigation, or a
potential source for future water supplies.
EPA and state officials determine that the migration of
contaminated ground water is under control (i.e., not con-
tinuing to spread in concentrations above levels of concern)
•when ongoing monitoring shows that the contaminant
plume is not expanding or negatively impacting surface
•waters (U.S. EPA, 1999). Preventing further migration
of contaminated ground water may result from an action
taken, such as installation of a "pump and treat" or subsur-
face barrier system, or because of natural attenuation of the
contaminants. A determination of whether migration has
been prevented is based on monitoring data (usually from
hundreds of analytical samples) collected from ground
•water wells located within and surrounding the spatial
extent of the ground water plume (U.S. EPA, 1999, 2005c).
This indicator describes the percentage of NPL Indica-
tor Baseline sites and RCRA Cleanup Baseline sites where
government officials have determined that contaminated
ground water is not continuing to spread in concentrations
above levels of concern (e.g., that exceed the appropri-
ate drinking water standards). This indicator covers both
"Final" and "Deleted" NPL Indicator Baseline sites, and
all 1,968 RCRA Cleanup Baseline sites. The percentage
of sites \vhere ground water contamination continues to
spread is also noted, as well as the number of sites where
there are insufficient data to make a finding. The intention
of the indicator is not to capture an "action" or "adminis-
trative determination" on the part of EPA, but to convey
the underlying pressure on the environment and poten-
tial for human health effects resulting from contaminated
ground water.
What the Data Show
In 2007, there were 1,968 sites on the RCRA Cleanup
Baseline. Of the high-priority RCRA Cleanup Baseline
sites, the percentage of sites where contaminated ground
•water has been determined to be under control increased
from 32 percent (554 out of 1,714 sites) in fiscal year (FY)
2000 to 79 percent (1,548 out of 1,968 sites) in FY 2007
(Exhibit 4-25, panel A). This increase represents a com-
bination of sites \vhere mitigation has halted the spread of
contaminated ground water and sites where sufficient data
have been collected to show that contaminated ground
•water migration was not continuing, regardless of mitiga-
tion activities. The percentage of sites where officials have
determined that contaminated ground water was spreading
above levels of concern decreased from 18 percent (306
out of 1,714 sites) in FY 2000 to less than 5 percent (94 out
of 1,968 sites) in FY 2007. These sites, and the remaining
326 sites for which there are still insufficient data to make
a determination at the end of FY 2007, tend to be very
complex sites where the appropriate data have yet to be
collected due to high costs or technical difficulties.
Ground water has not been an issue at all Superfund
NPL sites. Of those Final and Deleted NPL Indicator Base-
line sites \vhere ground -water contamination is present, the
percentage -where contaminated ground -water has been
determined to be under control increased from 61 percent
(772 of 1,275 sites) in FY 2002 to 70 percent (977 of 1,392
sites) (Exhibit 4-25, panel B). As of the end of FY 2007,
contaminated ground -water -was confirmed to be spreading
above levels of concern at 15 percent (213) of these NPL
sites, -while the remaining 15 percent (202 sites) had insuffi-
cient data to confirm -whether contaminated ground -water
is spreading above levels of concern. These percentages do
not include NPL Indicator Baseline sites classified as "non-
ground -water" sites.
Indicator Limitations
• The NPL does not represent all of the contaminated
or potentially contaminated sites listed in the Com-
prehensive Environmental Response, Compensation,
and Liability Information System (CERCLIS) database,
•which contains information on thousands of hazardous
•waste sites, potential hazardous waste sites, and remedial
activities across the nation. A small percentage (less than
1 percent) of the total number of final and deleted NPL
sites are excluded from the NPL Indicator Baseline for
reasons of consistency.
• The indicator covers the 1,714 RCRA Cleanup Base-
line sites tracked from 2000 to 2005 and the 1,968 sites
tracked in 2006 and 2007, and not the entire group
of 3,746 hazardous waste management sites currently
believed to be subject to RCRA Corrective Action re-
quirements (i.e., initial assessments, and if needed more
thorough investigations and cleanups).
EPA's 2008 Report on the Environment
4-47
-------
Migration of Contaminated Ground Water Under Control at
High-Priority Cleanup Sites (continued)
The extent to which people have been affected, or could
be affected, by the contaminated ground water at NPL
or RCRA Cleanup Baseline sites is not considered in
this indicator, but is addressed in the Current Human
Exposures Under Control at High-Priority Cleanup
Sites indicator (p. 4-44).
The indicator does not address ground water contami-
nated at other types of sites, such as sites with leaking
underground storage tanks and other sites being ad-
dressed solely by state cleanup programs.
Concentrations of toxic and hazardous contaminants in
ground water that must not be exceeded to designate a
site as under control vary somewhat from state to state,
though they fall within a range determined to be ac-
ceptable to EPA (U.S. EPA 2005a,c).
This indicator is based on the certification by a re-
sponsible official that the criteria necessary to designate
•whether contaminated ground water is continuing to
spread above levels of concern have been met (U.S. EPA,
1999, 2005a,b). Trends in the number of sites where the
spread of contaminated ground water has been shown to
occur above levels of concern may be underestimated to
the extent that certification lags behind the migration of
contaminated ground water or certification is delayed due
to insufficient or outdated information.
Data Sources
Data for this indicator were provided by EPA's Office
of Solid Waste and Emergency Response (OSWER). A
list showing the current status of every RCRA baseline
site is published online (U.S. EPA, 2007). A summary
of the status of Superfund NPL sites is available online
(U.S. EPA, 2005c); information on the current status
of any individual NPL site can be queried using EPA's
CERCLIS database (U.S. EPA, 2006) (http://cfpub.epa.
gov/supercpad/cursites/srchsites.cfm). Data for previous
years are not publicly accessible, however, and must be
requested from OSWER.
References
U.S. EPA (United States Environmental Protection
Agency). 2007. Facilities on the RCRA 2008 GPRA
corrective action baseline. Report generated 10/25/2007.
U.S. EPA. 2006. CERCLIS database. Accessed September
14, 2006.
Exhibit 4-25. Status of migration of contaminated
ground water under control at high-priority
cleanup sites in the U.S., fiscal years 2000-2007
A. RCRA Cleanup Baseline sites (2000-2007)3
2,000
1,500
1,000
500
1,968 1,968
1,714 1,714 1,714 1,714 1,714 1,714
854
306
554
(32%
of
total)
734
271
709
(41%
of
total)
610
231
873
(51%
of
total)
475
191
1,048
(61%
of
total)
358
157
1,199
(70%
of
total)
257
115
1,342
(78%
of
total)
416
10(1
1,452
(74%
of
total)
326
94
1,548
(79%
of
total)
2000 2001 2002 2003 2004 2005 2006 2007
Fiscal year
D Non-ground
water sites
D Insufficient
data0
Q Contaminated
ground water
is spreading
above levels
of concern
D Under control
(contaminated
ground water
is not continu-
ing to spread
in concentra-
tions above
levels of
concern)d
2,000
1,500
.-1,000
500
B. Superfund National Priorities List
Indicator Baseline sites (2002-2007)"
1/1*1 1./I9/I 1,494 1-544 1,5541,554
219
212
291
772
(61%
of
total)
219
201
248
826
(65%
of
total)
188
178
247
881
(67%
of
total)
169
226
212
937
(68%
of
total)
162
221
213
958
(69%
of
total)
162
202
213
977
(70%
of
total)
2002 2003
2004 2005 2006
Fiscal year
2007
aThe RCRA Cleanup Baseline changed in 2006 from 1,714 to
1,968 sites.
bThe Superfund NPL Indicator Baseline changed in 2005 from
1,494 to 1,544 sites and in 2006 from 1,544 to 1,554 sites.
°For RCRA Cleanup Baseline sites and Superfund NPL Indicator
Baseline sites, "insufficient data" includes sites officially
classified as "insufficient data" or "no status."
dFor calculating the percentage of Superfund NPL Indicator
Baseline sites in the "under control" category, the total does not
include "non-ground water" sites.
Data source: U.S. EPA, 2005c, 2006, 2007
4-48
EPA's 2008 Report on the Environment
-------
INDICATOI
Migration of Contaminated Ground Water Under Control at
High-Priority Cleanup Sites (continued)
U.S. EPA. 2005a. Draft Superfund environmental indicators
guidance manual: Long-term human health revisions.
U.S. EPA. 2005b. Frequently asked questions—human
exposure under control (HE) and migration of contami-
nated ground-water under control (GM) environmental
indicators.
U.S. EPA. 2005c. Migration of contaminated ground
•water under control. Accessed December 13, 2005.
U.S. EPA. 1999. Interim-final guidance for RCRA
corrective action environmental indicators.
4.6.3 Discussion
What These Indicators Say About Trends in
Contaminated Lands and Their Effects on
Human Health and the Environment
The indicators provide insights into trends in protecting
humans and ground water from the nation's most contaminated
lands. In 2007, 93 percent of the facilities on the Resource
Conservation and Recovery Act (RCRA) Cleanup Baseline
sites showed that human exposure to contamination in excess
of health-based standards was being prevented, while ground
water was not spreading above levels of concern at 79 percent
of the facilities. Similarly in 2007, the Superfund National
Priorities List (NPL) Indicator Baseline sites showed that human
exposure to contamination in excess of health-based standards
has been prevented at 82 percent of the sites, and ground water
has been prevented from spreading above levels of concern at 70
percent of the sites with ground water contamination.
Limitations, Gaps, and Challenges
The two ROE indicators are limited in their ability to address
the question. Currently, there is no single information source that
tracks the extent of contaminated land nation-wide. A substantial
amount is known about thousands of the most contaminated
sites on the Superfund NPL Indicator Baseline sites and facili-
ties on the RCRA Cleanup Baseline, which have been the focus
of in-depth studies and resource-intensive cleanup operations.
Although these facilities are some of the most seriously contami-
nated sites in the country, they do not reflect the full universe of
contaminated sites or even the full universe of seriously contami-
nated sites. EPA would like to have information on other sites
that require extensive cleanup, including sites contaminated with
radioactive materials from historical nuclear weapons production,
sites \vith leaking underground storage tanks, smaller accidental
spill sites, and other cleanup sites managed by a variety of local,
state, and federal authorities. Collectively, these contaminated
sites outnumber the combined Superfund NPL Indicator Baseline
sites and RCRA Cleanup Baseline facilities.
EPA \vould also like to have information on the actual or
potential acreage of contaminated land and is developing data
for sites subject to Agency cleanup programs. Additionally,
EPA -would like to better understand the types of contamina-
tion from all sources nationally. Even -where national data on
contaminated sites are available, the affected area and the types
and severity of contamination vary -widely from site to site,
making accurate trend analysis, aggregation, and generaliza-
tion difficult or impossible. There is no comprehensive data
source to determine the extent of these lands, populations that
may be affected, and the potential for contamination to have
harmful human health or ecological effects. Further, EPA is
interested in knowing how much previously contaminated
land has been returned to productive uses. Data associated
•with the use of previously contaminated land could help
answer the question of trends and effects of contaminated land
and the question of trends and effects of land use.
Current gaps in data on contaminated lands stem from a variety
of factors and challenges, including the multi-jurisdictional
responsibilities for identifying, managing, and cleaning up
contaminated lands; a focus in most contaminated lands data
sets on measures of regulatory compliance and associated activi-
ties; high costs to identify, inventory, study, and clean up large,
complicated sites; and complexity in the effects of contaminated
lands on human health and the environment, including unique
site characteristics and the inability to generalize information
over large geographic areas.
EPA's 2008 Report on the Environment
4-49
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-------
Chapter 5
Human Exposure
and Health
-------
Contents
5.1 Introduction 5-3
5.1.1 The Environmental Public Health Paradigm 5-4
5.1.2 Establishing Linkages Between Environmental Contaminants and Health Outcomes 5-5
5.1.3 Overview of the Data 5-5
5.1.4 Organization of This Chapter 5-6
5.2 What Are the Trends in Human Exposure to Environmental Contaminants, Including
Across Population Subgroups and Geographic Regions? 5-7
5.2.1 Introduction 5-7
5.2.2 ROE Indicators 5-9
5.2.3 Discussion 5-29
5.3 What Are the Trends in Health Status in the United States? 5-31
5.3.1 Introduction 5-31
5.3.2 ROE Indicators 5-32
5.3.3 Discussion 5-38
5.4 What Are the Trends in Human Disease and Conditions for Which Environmental
Contaminants May Be a Risk Factor, Including Across Population Subgroups and
Geographic Regions? 5-39
5.4.1 Introduction 5-39
5.4.2 ROE Indicators 5-42
5.4.3 Discussion . . . 5-68
-------
5.1 Introduction
The health of the human population can be influenced by
many factors, one of which is exposure to environmental
contamination. Protecting human health from the effects
of environmental contaminants is therefore an integral part of
EPA's mission. Protecting, sustaining, or restoring the health of
people and communities is central to EPA's various research
and regulatory programs. In fulfilling its mission, EPA examines
the human health impacts of contamination (physical, chemi-
cal, biological, or radiological) in air, in water, and on the land.
Thorough study of adverse health effects associated with envi-
ronmental contaminants enables the Agency to evaluate harmful
levels of exposure and issue guidelines for the safe production,
handling, and management of hazardous substances.
As described in Chapters 2 through 4, people can be exposed
to environmental contaminants in a variety of ways, and many
contaminants are known to be or suspected of causing human
disease. Identifying (1) the extent to which human exposures
may be occurring or may have occurred and (2) measures of
health outcomes possibly influenced by environmental expo-
sures is important in determining where further study or public
health interventions may be necessary. For example, the pres-
ence or patterns of elevated levels of environmental contami-
nants, as measured in human tissue through biomonitoring, is
of interest. Similarly, a high or increasing rate of a particular
cancer for which a hazardous substance in the environment
may be a contributing factor is of interest. In addition, tracking
exposures and health condition across segments of the popula-
tion such as gender, race or ethnicity, or geographic location
helps to identify differences across subgroups and guide public
health decisions and strategies.
In this chapter, EPA seeks to assess trends in human exposure and
disease or conditions that may be associated with environmental
factors on a national scale. Biomonitoring and health outcome
indicators are presented to address three fundamental questions:
• What are the trends in human exposure to environ-
mental contaminants, including across population
subgroups and geographic regions? Data on trends
in exposure levels provide an opportunity to evaluate the
extent to which environmental contaminants are present
in human tissue, independent of the occurrence of spe-
cific diseases or conditions. To address this question, this
chapter focuses on biomonitoring indicators (or biomarkers
of exposure) for environmental contaminants such as lead,
mercury, and pesticides.
• What are the trends in health status in the United
States? Here the report uses several general health outcome
indicators (life expectancy, infant mortality, and general
mortality) to provide a broad picture of health in the U.S.
Trends in these indicators provide a general context for
understanding trends in specific diseases and conditions that
may in part be linked with the environment.
• What are the trends in human disease and condi-
tions for which environmental contaminants may
be a risk factor, including across population sub-
groups and geographic regions? This question looks at
the occurrence of diseases and conditions that are known
EPA's 2008 Report on the Environment (ROE): Essentials
ROE Approach
This 2008 Report on the Environment:
• Asks questions that EPA considers
important to its mission to protect
human health and the environment.
• Answers these questions, to the extent
possible, with available indicators.
• Discusses critical indicator gaps, limita-
tions, and challenges that prevent the
questions from being fully answered.
ROE Questions
The air, water, and land chapters (Chapters
2, 3, and 4) ask questions about trends in
the condition and/or extent of the envi-
ronmental medium; trends in stressors to
the medium; and resulting trends in the
effects of the contaminants in that medium
on human exposure, human health, and
the condition of ecological systems.
The human exposure and health and
ecological condition chapters (Chapters
5 and 6) ask questions about trends in
aspects of health and the environment
that are influenced by many stressors
acting through multiple media and by
factors outside EPA's mission.
ROE Indicators
An indicator is derived from actual mea-
surements of a pressure, state or ambient
condition, exposure, or human health or
ecological condition over a specified geo-
graphic domain. This excludes indicators
such as administrative, socioeconomic, and
efficiency indicators.
Indicators based on one-time studies are
included only if they were designed to serve
as baselines for future trend monitoring.
All ROE indicators passed an independent
peer review against six criteria to ensure
that they are useful; objective; transparent;
and based on data that are high-quality,
comparable, and representative across space
and time.
Most ROE indicators are reported at the
national level. Some national indicators
also report trends by region. EPA Regions
were used, where possible, for consistency
and because they play an important role in
how EPA implements its environmental
protection efforts.
Several other ROE indicators describe
trends in particular regions as examples of
how regional indicators might be included
in future versions of the ROE. They are
not intended to be representative of trends
in other regions or the entire nation.
EPA will periodically update and revise
the ROE indicators and add new indicators
as supporting data become available. In the
future, indicators will include information
about the statistical confidence of status
and trends. Updates will be posted elec-
tronically at http://www.epa.gov/roe.
Additional Information
You can find additional information about
the indicators, including the underly-
ing data, metadata, references, and peer
review, at http://www.epa.gov/roe.
EPA's 2008 Report on the Environment
5-3
-------
or suspected to be caused (to some degree) or exacerbated
by exposures to environmental contaminants. This chapter
uses a spectrum of indicators for health outcomes—such as
cancer, asthma, and birth outcomes—to address this ques-
tion. Both morbidity and mortality statistics are considered.
These ROE questions are posed without regard to whether
indicators are available to answer them. This chapter presents the
indicators available to answer these questions, and also points out
important gaps where nationally representative data are lacking.
This chapter is not intended to be exhaustive in addressing
these questions, nor is it intended to be a risk assessment or
epidemiological study. Rather, it provides an overview of
selected indicators of human exposure and disease over space
and time, based on key data sources with sufficiently robust
design and quality assurance.
The indicators used here are based on data sets representa-
tive of the national population; they are not based on data
from targeted populations or tied to specific exposures or
releases. Therefore, these data sets cannot and should not be
used to draw conclusions about linkages or causal relationships
between a particular health outcome and contaminant; nor is
it possible to directly link the health outcome or biomonitor-
ing indicators to any of the indicators of emissions or ambient
pollutants in air, land, or water presented in earlier chapters
of this report. Though the chapter does not assess quantitative
relationships between the measures of environmental contam-
inants and diseases, it does present some qualitative discussion
of the research that has examined some of these relationships
to help explain why EPA has included particular indicators.
Sections 5.1.1 and 5.1.2 detail important principles guiding the
selection and interpretation of exposure and health indicators
used in this report.
5.1.1 The Environmental Public
Health Paradigm
The relationship among and between environmental con-
tamination, exposure, and disease is complex. Development of
disease is multi-faceted. Relationships between environmental
exposures and various health outcomes can only be established
through well-designed epidemiological, toxicological, and
clinical studies. An understanding of these factors provides
critical context for this chapter.
The environmental public health paradigm shown in Exhibit
5-11 illustrates the broad continuum of factors or events that
may be involved in the potential development of human
disease following exposure to an environmental contaminant.
This series of events serves as the conceptual basis for under-
standing and evaluating environmental health. The exhibit
illustrates that for adverse health effects (clinical disease or
death) to occur, many things have to happen. A contaminant
must be released from its source, reach human receptors (via
air, water, or land), enter the human body (via inhalation,
ingestion, or skin contact), and be present within the body at
sufficient doses within individuals to cause biological changes
that may ultimately result in an observed adverse health effect.
The paradigm, however, is a linear, schematic depiction of a
process that is complex and multi-factorial. Exposure to an
environmental contaminant is rarely the sole cause of an adverse
Exhibit 5-1. Environmental public health paradigm
Contaminant
formation and release
from source
Transport/transformation
in the ambient
environment
Source: Adapted from Sexton et al., 1992
Adverse health
outcomes
Altered
structure/function
Exposure in the ambient
environment
- Individual
-Community
- Population
Entry into body
(dose)
D Air, water, and land
(Chapters 2-4)
Adapted from: Sexton, K., S.G. Selevan, D.K.Wagener, andJ.A. Lybarger.
1992. Estimating human exposures to environmental pollutants: Availability
and utility of existing databases. Arch. Environ. Health 47(6):398-407.
5-4
EPA's 2008 Report on the Environment
-------
health outcome. Environmental contaminant exposure is just
one of several factors that can contribute to disease occur-
rence or to the severity of a preexisting disease. Among the
other factors are diet, exercise, alcohol consumption, individual
genetic makeup, medications, and other pre-existing diseases.
Asthma, for example, can be triggered by environmental insult,
but environmental exposures are not the "cause" of all asthma
attacks. In addition, different contaminants can be a risk factor
for the same disease. Taking the same example, outdoor air pol-
lution and certain indoor air pollutants, such as environmental
tobacco smoke, can both exacerbate asthma symptoms. Further,
susceptibility to disease is different for each person; some indi-
viduals may experience effects from certain ambient exposure
levels while others may not.
Each block in Exhibit 5-1 can have indicators associated with
it. As shown, aspects of Chapters 2 through 4 may address
contaminant formation, release, transport, and transforma-
tion in the environment. Those chapters present indicators
for the presence of contaminants or other stressors affecting
air, water, and land, sometimes at locations in which people
may be exposed. Measurements of ambient exposure levels
are different than the biomonitoring indicators (biomarkers of
exposures) introduced in this chapter. Other types of biomark-
ers exist (e.g., biomarkers of susceptibility and biomarkers of
effect); because national-scale data do not exist for these bio-
markers, they are not covered in this chapter at this time.
The presence of a contaminant in the environment or within
human tissue alone does not mean disease will occur. Further-
more, identification of diseases for which environmental con-
taminants are risk factors does not mean exposure has occurred
or contributed to that disease. However, extensive and collab-
orative data collection and research efforts across the scientific
community continue to strengthen our understanding of the
relationships between environmental exposures and disease.
This chapter uses indicators that are tied into the environmental
public health paradigm as one tool for discerning notable trends
in exposure and health. First, EPA presents biomonitoring indi-
cators to illustrate the general extent to which people are being
exposed to environmental contaminants. Second, indicators
of overall health status and specific diseases and conditions are
used to identify potential morbidity/mortality patterns, again
recognizing that environmental exposures are only one factor
that could influence reported trends.
5.1.2 Establishing Linkages
Between Environmental
Contaminants and Health
Outcomes
EPA uses the results of scientific research to help identify link-
ages between exposure to environmental contaminants and
certain diseases, conditions, or other health outcomes. EPA
relies on the possible linkages established through these types
of studies to identify environmental contaminants and health
outcomes of potential Agency interest (e.g., the indicators
used in this chapter). Examples include radon and lung cancer;
arsenic and cancer in several organs; lead and nervous system
disorders; disease-causing bacteria (such as E. coli O157:H7)
and gastrointestinal illness and death; and particulate mat-
ter and aggravation of cardiovascular and respiratory diseases.
Such relationships between exposure and disease have been
established through well-designed epidemiological studies
•with a defined or specified population (e.g., geographic loca-
tion, susceptible populations, occupational exposures) and
known environmental exposures.
The causes of many diseases and other health conditions are not
well established. In some cases, environmental contaminants are
considered important risk factors. In other cases, available data
suggest that environmental exposures are important, but proof is
lacking. Developing evidence that environmental contaminants
cause or contribute to the incidence of adverse health effects can
therefore be challenging, particularly for those effects occur-
ring in a relatively small proportion of the population or effects
•with multiple causes. In cases where exposure to an environ-
mental contaminant results in a relatively modest increase in
the incidence of a disease or disorder, a large sample size for the
study would be needed to detect a true relationship. In addition,
there may be factors related to both the exposure and the health
effect—confounding factors—that can make it difficult to detect
a relationship between exposure to environmental contaminants
and disease. In many cases, findings from studies in humans and/
or laboratory animals may provide suggestive (rather than con-
clusive) evidence that exposures to environmental contaminants
contribute to the incidence of a disease or disorder.
To reiterate, however, the national-scale ROE indicators do
not directly link exposure with outcome and cannot be used
to demonstrate causal relationships. However, when combined
•with other information, such as environmental monitoring
data and data from toxicological, epidemiological, or clini-
cal studies, these indicators can be an important key to better
understanding the relationship between environmental con-
tamination and health outcomes.
5.1.3 Overview of the Data
EPA draws on many resources and partnerships with other
federal, state, and local agencies for the health data and sta-
tistical reports that underlie the biomonitoring and health
outcome indicators used in this chapter. This chapter uses
three key types of data sources, each with its own strengths
and limitations:
• Data collected from living human subjects. This
includes both questionnaire-based information (e.g., the
National Center for Health Statistics' [NCHS's] National
Health Interview Survey, a nation-wide survey to collect
data on personal and demographic characteristics, illnesses,
and other topics) and biological specimens (such as NCHS's
National Health and Nutrition Examination Survey, which
collects and measures some chemicals in blood and urine
samples). This chapter focuses on data collection activi-
ties that have a national focus and use a probability-based
sampling design.
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• Vital statistics data. Vital statistics of interest for health
include births, deaths, and fetal deaths. Vital statistics
data used in this chapter include NCHS's National Vital
Statistics System.
• Data from surveillance activities. These include data
from active surveillance activities such as the National Can-
cer Institute's Surveillance, Epidemiology, and End Results
Program, which collects and publishes cancer incidence and
survival data from population-based cancer registries. It also
includes data from more passive collection systems, such as
the Centers for Disease Control and Prevention's (CDC's)
National Notifiable Disease Surveillance System, which
provides information about diseases that health providers
must report to state or local public health officials.
This chapter also takes advantage of several published docu-
ments that present and summarize in one place the findings
from many data collection activities (e.g., NCHS's Healthy
People 2010 Database). In addition, it uses some databases
that provide a single point of access to a variety of reports
and numeric public health data and ways to conduct analyses
of those data (e.g., CDC WONDER, CDC's Wide-ranging
OnLine Data for Epidemiologic Research).
The data sources used provide statistics across time, geographic
areas, and/or subpopulations such as age groups, races, and
ethnicities. Identifying possible differences among popula-
tion subgroups, as well as evidence of whether any differences
are narrowing or -widening, may reveal trends needing study
or intervention. This type of trend analysis is consistent with
national public health goals aimed at eliminating health
disparities across various groups (e.g., racial and ethnic groups,
low-income populations).2 It addresses a continuing concern
that minority and/or economically disadvantaged communi-
ties frequently may be exposed disproportionately to envi-
ronmental contaminants. Statistics for populations that may
be particularly susceptible to environmental contaminants,
such as children and pregnant women, are also examined.
However, the type and level of subpopulation breakdown
varies across data sets, sometimes making consistent presen-
tation of this information difficult. Standards according to
•which federal agencies report race and ethnicity statistics were
revised in 1997. The revised standards, which became effective
in 2003, expand the race and ethnicity categories for which
data are collected and are aimed at increasing comparability of
data among federal data systems. As vital records used to sup-
port federal data systems continue to be revised and come into
compliance with the 1997 requirements, future data reporting
and comparisons will be more straightforward.
This chapter presents health statistics, including race and
ethnicity subgroup categorization, as reported within the
original data source documents or databases. The presentation
of observed changes—temporally, spatially, or across sub-
groups—is descriptive, not quantitative. No statistical testing
•was performed (e.g., tests of statistical significance).
This chapter presents only data that meet the ROE indi-
cator definition and criteria (see Box 1-1, p. 1-3). Note
that non-scientific indicators, such as administrative and
economic indicators, are not included in this definition.
Thorough documentation of the indicators data sources and
metadata can be found online at http://www.epa.gov/roe.
All indicators were peer-reviewed during an independent
peer review process (again, see http://www.epa.gov/roe for
more information). Readers should not infer that the indica-
tors included reflect the complete state of the knowledge
on trends in health and exposure related to environmental
exposures. Many other data sources, publications, site-
specific research projects, and epidemiological studies have
contributed greatly to the current understanding of health
and exposure trends, but are not used because they do not
meet some aspect of the ROE indicator criteria.
5.1.4 Organization of This
Chapter
The rest of this chapter is organized into sections correspond-
ing to the three questions EPA seeks to answer about trends in
human health and exposure. Each section introduces the ques-
tion and its importance, presents the ROE indicators selected
to help answer the question, and discusses what the indicators,
taken together, say about the question. The ROE indicators pri-
marily include National Indicators, but in some cases National
Indicators are broken down by EPA Region to help to answer
the ROE question at a smaller geographic scale. Each section
concludes by highlighting the major challenges to answering
the question and identifying important information gaps.
Table 5-1 lists the indicators used to answer the three ques-
tions in this chapter and shows the locations where the
indicators are presented.
U.S. Department of Health and Human Services. 2000. Healthy people 2010:
Understanding and improving health. Second edition. Washington, DC: U.S.
Government Printing Office,
5-6
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>
Table 5-1. Human Exposure and Health—ROE Questions and Indicators
Question
What are the trends in human
exposure to environmental
contaminants, including
across population subgroups
and geographic regions?
What are the trends in health
status in the United States?
What are the trends in human
disease and conditions
for which environmental
contaminants may be a risk
factor, including across
population subgroups and
geographic regions?
Indicator Name
Blood Lead Level (N)
Blood Mercury Level (N)
Blood Cadmium Level (N)
Blood Persistent Organic Pollutants Level (N)
Blood Cotinine Level (N)
Urinary Pesticide Level (N)
Urinary Phthalate Level (N)
General Mortality (N)
Life Expectancy at Birth (N)
Infant Mortality (N)
Section Page
Cancer Incidence (N)
Childhood Cancer Incidence (N)
Cardiovascular Disease Prevalence (N) and Mortality (N/R)
Chronic Obstructive Pulmonary Disease Prevalence (N)
and Mortality (N/R)
Asthma Prevalence (N)
Infectious Diseases Associated with Environmental
Exposures or Conditions (N)
Birth Defects Prevalence and Mortality (N)
Low Birthweight (N)
Preterm Delivery (N)
5.2.2
5.2.2
5.2.2
5.2.2
2.4.2
5.2.2
5.2.2
5.3.2
5.3.2
5.3.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5-10
5-12
5-13
5-15
2-76
5-22
5-26
5-33
5-35
5-36
5-43
5-46
5-48
5-52
5-55
5-59
5-62
5-65
5-67
N = National Indicator
N/R = National Indicator displayed at EPA Regional scale
5.2 What Are the Trends
in Human Exposure
to Environmental
Contaminants, Including
Across Population
Subgroups and
Geographic Regions?
5.2.1 Introduction
Understanding the extent to which human populations are
being exposed to environmental contaminants helps iden-
tify those contaminants of potential public health concern
3 Landrigan, P.J., C.A. Kimmel, A. Correa, and B. Eskenazi. 2004. Children's
health and the environment: Public health issues and challenges for risk
assessment. Environ. Health Perspect. 112(2):257-265.
and populations who may be disproportionately exposed to
contaminants or uniquely vulnerable. For example, children
may have disproportionately heavy exposures to environ-
mental contaminants because they drink more water, breathe
more air, and eat more food per pound or kilogram of body
•weight than adults; further, children may be more vulnerable
to some environmental contaminants depending on the stage
of development during which exposure occurs.3'4 Evaluating
exposure across certain race or ethnic groups, or other poten-
tially susceptible subgroups, identifies possible variations in
exposures. Tracking the levels of environmental contaminants
in a population also enables an assessment of how exposures to
those contaminants are changing in that population over time.
Referring back to the environmental public health paradigm
presented in Section 5.1.1, measurements of human exposure
to environmental contaminants can be made in the ambient
environment (air, water, land), at the point of human con-
tact, or after contact and contaminant entry into the human
body has occurred. Box 5-1 further distinguishes the differ-
ent types of exposure measures. In answering this question,
the focus is on human biomonitoring, which involves the
4 World Health Organization. 2006. Principles for evaluating health risks
in children associated with exposure to chemicals. Environmental Health
Criteria 237.
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measurement of human tissues or excreta for direct or indirect
evidence of exposure to chemical, biological, or radiological
substances. The ambient contaminant measurements presented
in the media chapters are not considered here, nor can they be
directly linked with biomonitoring data presented to answer
this question.
Historically, human exposure has been defined as the amount
of a chemical, physical, or biological contaminant at the outer
boundary of the body available for exchange or intake via
inhalation, ingestion, or skin or eye contact.5 As such, human
exposure to environmental contaminants has been estimated
primarily through measurements of contaminant concentrations
in air, water, or soil, combined with estimates of the frequency
and duration of human contact with the contaminated media.
These resulting exposure estimates have provided a valuable
foundation for many of the regulatory and non-regulatory
actions that have been taken to limit exposure to ambient
contaminants. However, developments in data collection
techniques and analytical methods have improved the capability
to characterize human exposure via biomonitoring, which pro-
vides measurements of contaminants within the human body.
For a few environmental contaminants, particularly lead and
some other metals, biomonitoring has been used for exposure
characterization for a number of years. More recently, techniques
for biomonitoring have been expanded to include many addi-
tional environmental contaminants. These measurements provide
a tool that complements ambient measurements in characterizing
human exposure to environmental contaminants. However, con-
centrations of environmental contaminants reported at a national
level in blood, urine, or any other type of tissue cannot be used to
extrapolate directly to a particular source.
The use of biological markers (or biomarkers) builds on the
more traditional exposure assessment approach, providing
more information on the extent to which a contaminant
enters, remains, and acts in the body. Biomarker information
attempts to determine the extent to which a contaminant is
present in the body after entering through portals of entry
such as the eyes, skin, stomach, intestines, or lungs. Given
the complex set of factors that govern contaminants that are
absorbed and distributed in the body, a direct measurement
of the levels of a contaminant or related "marker" in the body
offers more information about exposure than measured ambi-
ent levels alone.
In general, a biomarker reports the level of a substance or a
marker (i.e., the product of an interaction between an agent
and some target molecule or cell) present in samples collected
from the body or produced by the body. Biomarkers of exposure
measure concentrations of a contaminant, its metabolite(s), or
reaction product(s) in the body fluids or tissue, most com-
monly blood or urine. Measurements can also be taken from a
variety of other body compartments, such as feces, breast milk,
hair, nails, exhaled air, and tissues obtained through biopsy or
autopsy. The exposure measure used to answer this question
focuses on biomarkers of exposure. Biomarkers of exposure do
not predict whether biological alterations and potential health
effect will result. Whether a particular exposure ultimately
results in an adverse health outcome depends on a host of fac-
tors, as is described in Section 5.1.
Box 5-1. Measuring Human Exposure
Various approaches can be used to measure or estimate the
levels of human exposures. No approach is best suited to
all environmental contaminants, and each approach has
strengths and -weaknesses. Available biomonitoring data are
used to answer the question on trends in human exposure to
environmental contaminants.
Ambient contaminant measurements: Historically,
human exposures have been estimated using environmental
measurements of ambient contaminant concentrations. One
limitation of ambient measurements is that the presence of a
contaminant in the environment may not be fully informa-
tive regarding the extent to which individuals are exposed.
In some cases, emissions data are used to model or estimate
ambient concentrations.
Models of exposure: This approach combines knowledge
of environmental contaminant concentrations with infor-
mation on people's activities and locations (e.g., time spent
•working, exercising outdoors, sleeping, shopping) to account
for the contact with contaminants. This approach requires
knowledge of contaminant levels where people live, work,
and play, as well as knowledge of their day-to-day activities.
Since model output is not a direct measure of environmen-
tal conditions or exposure, it is not considered to be a true
indicator of exposure.
Personal monitoring data: With personal monitoring,
the monitoring device is worn by individuals as they engage
in their normal day-to-day activities. This approach is
most commonly used in -workplace environments. Personal
monitoring data provide valuable insights into the source of
contaminants to which people are actually being exposed.
However, a challenge with personal monitoring (as with
biomonitoring) is ensuring that sufficient sampling is con-
ducted to be representative of the population being studied.
No national-scale personal monitoring data are available.
Biomonitoring data: Several environmental contaminants,
notably heavy metals and some pesticides and other persistent
organic pollutants, can accumulate in the body. These sub-
stances or their metabolites can be measured in human tissues
or fluids such as blood or urine. These residues reflect the
amount of contaminant that gets into or is present in the body,
but by themselves do not provide information on how the
person came into contact with the contaminant.
Aldrich,T.,J. Griffith, C. Cooke. 1993. Environmental epidemiology and risk
assessment. New York, NY:Van Nostrand Reinhold.
5-8
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5.2.2 ROE Indicators
The answer to the question on trends in human expo-
sure relies on national-scale biomonitoring data collected
as part of the Centers for Disease Control and Prevention's
(CDC's) National Health and Nutrition Examination Survey
(NHANES), primarily data collected from 1999 through
2002. As part of the survey, blood and urine samples are
routinely collected to measure certain contaminants (or their
metabolites) of public health concern. NHANES is conducted
annually, but the data are combined and reported for a 2-year
time period to provide more stable population estimates and
to obtain adequate sample sizes for many subgroup analyses.
CDC continues to process 2003-2004 and 2005-2006 survey
data; raw data for the 2003-2004 survey are available for some
data sets, but CDC-synthesized data and reports were not
available in time for inclusion in the ROE. The chemicals in
CDC's current suite of biomarkers were chosen based largely
on scientific data that suggest exposure in the U.S. population,
the seriousness of known or suspected health effects associated
•with some levels of exposure, the availability and adequacy of
analytical methods, and logistical and cost considerations.6
Seven individual or groups of contaminants from NHANES
are considered, including metals, persistent organic pollut-
ants, pesticides, and phthalates (Table 5-2). The data presented
represent data from NHANES in its entirety or a subset of the
original data, with emphasis on those compounds for which
CDC was able to calculate geometric means.7 The levels of
detection (LOD) presented in the indicators' exhibits vary
from chemical to chemical. A chemical's LOD is the level at
•which the measurement has a 95 percent probability of being
greater than zero. Percentile estimates that are less than the
LOD for the chemical analysis are reported as "
Geometric means are calculated by taking the log of each concentration, then
calculating the mean of those log values, and finally taking the antilog of that
mean. A geometric mean provides a better estimate of central tendency and
is influenced less by high values than is the arithmetic mean. This type of dis-
tribution is common when measuring environmental chemicals in blood or
urine. See Centers for Disease Control and Prevention. 2005.Third national
report on human exposure to environmental chemicals. NCEH publication
no. 05-0570.
Centers for Disease Control and Prevention. 2005.Third national report
on human exposure to environmental chemicals. NCEH publication no.
05-0570.
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INDICATOR
Blood Lead Level
Lead is a naturally occurring metal found in small
amounts in rock and soil. Lead has been used industri-
ally in the production of gasoline, ceramic products, paints,
metal alloys, batteries, and solder. While lead arising from
the combustion of leaded gasoline was a major source of
exposure in past decades, today lead-based paint and lead-
contaminated dust from paint are the primary sources of
lead exposure in the home. Lead levels can be measured in
blood or urine.
Lead is a neurotoxic metal that affects areas of the brain
that regulate behavior and nerve cell development (NR.C,
1993). Its adverse effects range from subtle responses to
overt toxicity, depending on how much lead is taken into
the body and the age and health status of the person (CDC,
1991). Lead is one of the few pollutants for which biomoni-
toring and health effect data are sufficient to clearly evalu-
ate environmental management efforts to reduce lead in
the environment.
Infants, children, and fetuses are more vulnerable to the
effects of lead because the blood-brain barrier is not fully
developed in them (Nadakavukaren, 2000). Thus, a smaller
amount of lead will have a greater effect on children than
on adults. In addition, ingested lead is more readily absorbed
into a child's bloodstream, while adults absorb only 10 per-
cent. Because of lead's adverse effects on cognitive devel-
opment, the Centers for Disease Control and Prevention
Exhibit 5-2. Blood lead concentrations for the U.S. population age 1 year and older by selected
demographic groups, 1999-2002
Geometric mean and selected percentiles
for blood lead concentrations (ug/dL)a
Total, agel year and
older
Sex
Male
Female
Race and ethnicityb
Black, non-Hispanic
Mexican American
White, non-Hispanic
Age group
1-5 years
6-11 years
12-19 years
20+ years
Survey years
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
Sample size
7,970
8,945
3,913
4,339
4,057
4,606
1,842
2,219
2,742
2,268
2,716
3,806
723
898
905
1,044
2,135
2,231
4,207
4,772
Geometric mean
1.7
1.5
2.0
1.8
1.4
1.2
1.7
1.8
1.5
1.6
1.4
22
1.7
1.5
1.3
1.1
0.9
1.8
1.6
50th
1.6
1.4
1.8
1.7
1.3
1.1
1.7
1.6
1.8
1.5
1.6
1.4
2.2
1.5
1.3
1.1
1.0
0.8
1.7
1.6
75th
2.4
2.2
2.9
2.7
1.9
1.8
2.8
2.5
2.7
2.2
2.4
2.1
3.3
2.5
2.0
1.6
1.4
1.2
2.5
2.2
90th
3.8
3.4
4.4
3.9
3.0
2.6
4.2
4.2
4.2
3.6
3.6
3.1
4.8
4.1
3.3
2.7
2.3
1.9
3.9
3.6
95th
4.9
4.4
6.0
5.3
4.0
3.6
5.7
5.7
5.8
5.4
5.0
4.1
7.0
5.8
4.5
3.7
2.8
2.7
5.2
4.6
aRefer to CDC 2005 for confidence intervals for reported values.
bOther racial and ethnic groups are included in
Data source: CDC, 2005
the "total" only.
5-10
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INDICATOI
Blood Lead Level (continued)
(CDC) have defined an elevated blood lead level as equal
to or greater than 10 micrograms per deciliter (jag/dL) for
children under 6 years of age (CDC, 2005).
This indicator is based on data collected by the National
Health and Nutrition Examination Survey (NHANES).
NHANES is a series of surveys conducted by CDC's
National Center for Health Statistics that is designed to col-
lect data on the health and nutritional status of the civilian,
non-institutionalized U.S. population using a complex,
stratified, multistage, probability-cluster design. CDC began
monitoring blood lead in 1976 as part of NHANES II,
•which covered the period from 1976 through 1980. Blood
lead was also monitored in NHANES III, which covered
the period between 1988 and 1994. CDC's National Center
for Environmental Health conducted the laboratory analy-
ses for the biomonitoring samples. Beginning in 1999,
NHANES became a continuous and annual national survey,
visiting 15 U.S. locations per year and surveying and report-
ing for approximately 5,000 people annually.
What the Data Show
The overall geometric mean blood lead levels among
all participants age 1 year and older from NHANES
1999-2000 and 2001-2002 were 1.7 ng/dL and 1.5 jag/
dL, respectively (Exhibit 5-2). Adults 20 years and older
had a geometric mean lead level of 1.6 (ag/dL during the
2001-2002 NHANES. For this same period, males and
females had geometric mean lead levels of 1.8 (ag/dL and
1.2 (ag/dL, respectively. For non-Hispanic blacks, Mexican
Americans, and non-Hispanic whites during 2001-2002,
the geometric mean lead levels were 1.7, 1.5, and 1.4 jag/
dL, respectively. The geometric mean blood levels among
every age, race, and ethnic group, as well as for both males
and females, declined in the most recent 2001-2002 survey.
Of all age groups, children age 1 to 5 had the highest
geometric mean lead level, at 1.7 (ag/dL. However, this age
group also showed the largest decline between 1999-2000
and 2001-2002 (2.2 ng/dL to 1.7 ng/dL). Children age 6 to
11 and 12 to 19 had reported geometric mean lead levels of
1.3 and 0.9 ng/dL, respectively, for the 2001-2002 survey.
Blood lead levels have declined steadily since NHANES
surveillance of blood lead levels across the U.S. began
in 1976. NHANES II (1976-1980) reported a geometric
mean blood lead level of 14.9 (ag/dL among children age
1 to 5, the population at the highest risk for lead exposure
and effects; just over 88 percent of this high-risk popula-
tion had blood lead levels greater than or equal to 10 jag/
dL (CDC, 2004a). Data collected from 1991 to 1994 as
part of NHANES III (phase 2) showed that the geometric
mean blood lead level for children age 1 to 5 was 2.7 jag/
dL, with 4.4 percent of children age 1 to 5 having blood
lead levels greater than or equal to 10 (ag/dL (CDC, 2005).
Children age 1 to 5 whose blood was sampled as part of the
1999-2002 survey had a geometric mean blood lead level
of 1.9 (ag/dL, with 1.6 percent of the children having blood
lead levels greater than or equal to 10 (ag/dL (CDC, 2005).
(Data not shown.)
Indicator Limitations
• Because the data from NHANES 1999-2000 and
2001-2002 represent only two survey periods, changes in
estimates between the two time periods do not neces-
sarily reflect a trend. Earlier data sets are available (e.g.,
NHANES III), but the data are not directly comparable
to NHANES 1999-2002. As CDC releases additional
survey results (e.g., 2003-2004), it will become possible
to more fully evaluate trends (CDC, 2002, 2004b).
Data Source
Data used for this indicator were extracted from two CDC
reports that present results of the ongoing NHANES
(CDC, 2004a, 2005). The underlying laboratory data sup-
porting CDC's reports are available online in SAS® trans-
port file format at http://www.cdc.gov/nchs/about/major/
nhanes/datalink.htm.
References
CDC (Centers for Disease Control and Prevention). 2005.
Third national report on human exposure to environmen-
tal chemicals. NCEH publication no. 05-0570.
CDC. 2004a. Children's blood lead levels in the United
States. Accessed October 11, 2005.
CDC. 2004b. NHANES analytic guidelines. June 2004
version,
CDC. 2002. NHANES 1999-2000 addendum to the
NHANES III analytic guidelines. Updated August 30,
2002.
CDC. 1991. Preventing lead poisoning in young children.
Accessed November 21, 2004.
Nadakavukaren, A. 2000. Our global environment: A
health perspective. Fifth edition. Prospect Heights, IL:
Waveland Press, Inc.
NRC (National Research Council). 1993. Measuring lead
exposure in infants, children, and other sensitive popula-
tions. Washington, DC: National Academies Press.
EPA's 2008 Report on the Environment
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INDICATOR
Blood Mercury Level
Mercury is a naturally occurring metal. However,
through many industrial processes (e.g., chemical
manufacturing operations, coal combustion), mercury is
•widespread and persistent in the environment. It is found
in elemental form and in various organic compounds and
complexes. Methylmercury (an organic form) can accumu-
late in the food chain in aquatic systems and lead to high
concentrations in predatory fish. Consumption of con-
taminated fish is the major source of human exposure to
methylmercury in the U.S. (NRC, 2000).
The human health effects of mercury are diverse and
depend on the forms of mercury encountered and the
severity and length of exposure. Fetuses and children may
be more susceptible to mercury than adults, with concern
for the occurrence of developmental and neurological
health effects (NRC, 2000). Prenatal exposures interfere
•with the growth and migration of neurons and have the
potential to cause irreversible damage to the developing
central nervous system.
This indicator quantifies the blood mercury levels
(includes organic and inorganic) among U.S. women
age 16 to 49 and children age 1 to 5, using data from the
1999-2002 National Health and Nutrition Examination
Survey (NHANES). NHANES does not report blood
mercury data for adult males. NHANES is a series of
surveys conducted by the Centers for Disease Control and
Prevention's (CDC's) National Center for Health Statistics
that is designed to collect data on the health and nutritional
status of the civilian, non-institutionalized U.S. population
using a complex, stratified, multistage, probability-cluster
design. CDC's National Center for Environmental Health
conducted the laboratory analyses for the biomonitoring
Exhibit 5-3. Blood mercury concentrations for U.S. women age 16-49 years and children (male and
female) age 1-5 years by selected demographic groups, 1999-2002
Geometric mean and selected percentiles
for mercury concentrations (ug/L)a
Survey years Sample size Geometric mean 50tn
Women age 16-49 years
Total, women age
16-49 years
Race and ethnicity
Black, non-Hispanic
Mexican American
White, non-Hispanic
Children age 1-5 years
Total, children age
1-5 years
Sex
Male
Female
Race and ethnicity
Black, non-Hispanic
Mexican American
White, non-Hispanic
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2002
1999-2002
1999-2002
1,709
1,928
370
436
579
527
588
806
705
872
424
526
447
aRefer to CDC, 2005, for confidence intervals for reported values.
Data source: CDC, 2004a, 2005
0.8
1.1
0.8
0.7
0.9
0.8
0.3
0.4
0.3
0.9
0.7
1.1
0.9
0.7
0.9
0.8
0.3
0.3
0.2
75th
2.0
1.7
1.8
1.4
1.1
1.9
1.5
0.7
0.6
0.5
90th
4.9
3.0
4.8
3.2
2.6
2.1
5.0
3.0
1.4
1.2
1.5
1.4
1.2
95th
7.1
4.6
5.9
4.1
4.0
3.5
6.9
4.6
2.3
1.9
2.4
1.9
1.8
5-12
EPA's 2008 Report on the Environment
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INDICATOI
Blood Mercury Level (continued)
samples. Beginning in 1999, NHANES became a continu-
ous and annual national survey. Data for 1999-2000 and
2001-2002 are presented here as a baseline, with the intent
of reporting trends across time as more data become avail-
able in the future.
What the Data Show
Exhibit 5-3 presents the geometric mean and fourper-
centiles of blood mercury for selected populations
sampled during NHANES 1999-2000 and 2001-2002.
For women age 16-49 years there was a small decline in
geometric mean blood mercury levels from 1999-2000
and 2001-2002 (1.0 and 0.8 micrograms per liter [ng/L],
respectively). Decreases occurred for each of the fourper-
centiles, but were most pronounced at the 90th and espe-
cially 95th percentiles. Of women tested between 1999 and
2002, 5.7 percent had mercury levels measured between
5.8 and 58 ng/L (data not shown). For children age 1 to 5,
the geometric mean remained the same at 0.3 ng/L.
When the geometric means are stratified across three
racial/ethnic groups, black, non-Hispanic women age 16
to 49 had the highest levels during both the 1999-2000 and
2001-2002 surveys (1.4 and 1.1 ng/L, respectively), followed
by white non-Hispanics (0.9 and 0.8 ng/L, respectively),
and Mexican Americans (0.8 and 0.7 ng/L, respectively).
Among children age 1 to 5, black non-Hispanics have the
highest geometric mean between 1999 and 2002 (0.5 Hg/L),
followed by Mexican Americans (0.4 Hg/L) and white non-
Hispamcs (0.3 ng/L) (CDC, 2004a).
Indicator Limitations
• Because the data from NHANES 1999-2000 and
2001-2002 represent only two survey periods, changes in
estimates between the two time periods do not necessarily
reflect a trend. As CDC releases additional survey results
(e.g., 2003-2004) it will become possible to more fully
evaluate trends (CDC, 2002, 2004b).
• Generally recognized guidelines for blood levels of
mercury have not been established.
Data Sources
Data used for this indicator were extracted from two CDC
reports that present results of the ongoing NHANES (CDC,
2004a, 2005). The underlying laboratory data supporting
CDC's reports are available online in SAS® transport file
format at http://www.cdc.gov/nchs/about/major/nhanes/
datalink.htm.
References
CDC (Centers for Disease Control and Prevention). 2005.
Third national report on human exposure to environmen-
tal chemicals. NCEH publication no. 05-0570.
CDC. 2004a. Blood mercury levels in young children and
childbearing-aged women—United States, 1999-2002.
MMWR 53:1018-1020.
CDC. 2004b. NHANES analytic guidelines. June 2004
version,
CDC. 2002. NHANES 1999-2000 addendum to the
NHANES III analytic guidelines. Updated August 30, 2002.
NRC (National Research Council). 2000. Toxicologi-
cal effects of methylmercury. Washington, DC: National
Academies Press.
Blood Cadmium Level
Cadmium is a metal that is usually found in nature com-
bined with oxygen, chlorine, or sulfur. Cadmium enters
the environment from the weathering of rocks and miner-
als that contain cadmium. Exposure to cadmium can occur
in occupations such as mining or electroplating, where
cadmium is produced or used. Cadmium exposure can also
occur from exposure to cigarette smoke (CDC, 2005).
Cadmium and its compounds are toxic to humans and
animals. Once absorbed into the human body, cadmium
can accumulate in the kidneys and remain in the body
for decades. Chronic exposure to cadmium can result in
serious kidney damage. Osteomalacia, a bone disorder
similar to rickets, is also associated with long-term inges-
tion of cadmium. Acute airborne exposure, as occurs from
\velding on cadmium-alloy metals, can result in swelling
(edema) and scarring (fibrosis) of the lungs (CDC, 2005).
This indicator reflects blood cadmium concentrations in
micrograms per liter (jag/L) for the U.S. population, age
1 year and older, as measured in the 1999-2002 National
Health and Nutrition Examination Survey (NHANES).
NHANES is a series of surveys conducted by the Centers
for Disease Control and Prevention's (CDC's) National
Center for Health Statistics that is designed to collect data
on the health and nutritional status of the civilian, non-
institutionalized U.S. population using a complex, strati-
fied, multistage, probability-cluster design. CDC's National
Center for Environmental Health conducted the laboratory
analyses for the biomonitoring samples. Beginning in 1999,
EPA's 2008 Report on the Environment
5-13
-------
INDICATOR
Blood Cadmium Level (continued)
NHANES became a continuous and annual national survey;
biomonitoring for certain environmental chemicals also was
implemented. Data for 1999-2000 and 2001-2002 are pre-
sented here as a baseline, with the intent of reporting trends
across time as more data become available in the future.
What the Data Show
Exhibit 5-4 presents the geometric means and selected
percentiles for blood cadmium among participants age 1
year and older from NHANES 1999-2000 and 2001-2002.
During the 2001-2002 survey, the overall geometric mean
blood cadmium level was not calculated because of the
high number of samples that were below the method's
limit of detection. However, the blood cadmium levels
at the four different percentiles (50th, 75th, 90th, and 95th)
are very similar across the two survey periods, with levels
ranging between 0.3 and 1.4 ng/L. The blood cadmium
measurements were similar among males and females, as
•well as among the racial or ethnic groups sampled across
both time periods.
During the 1999-2000 survey, the overall geometric
mean among participants age 20 or older was slightly
higher (0.5 ng/L) than the geometric mean among the
12-19 age group (0.3 (ag/L). Compared to participants in
the other age groups, those older than 20 years had higher
cadmium levels for each of the four selected percentiles
Exhibit 5-4. Blood cadmium concentrations for the U.S. population age 1 year and older by selected
demographic groups, 1999-2002
Geometric mean and selected percentiles
for cadmium concentrations (ug/L)a b c
Total, agel year
and older
Sex
Male
Female
Race and ethnicity
Black, non-Hispanic
Mexican American
White, non-Hispanic
Age group
1-5 years
6-11 years
12-19 years
20+years
Survey years
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
Sample size
7,970
8,945
Geometric mean
NC
0.3
NC
-------
INDICATOI
Blood Cadmium Level (continued)
during both survey periods. During the 1999-2000 survey,
approximately half of all participants under the age of
12 had non-detectable blood cadmium concentrations.
This proportion increased to about 90 percent during the
2001-2002 survey.
Indicator Limitations
• Because the data from NHANES 1999-2000 and
2001-2002 represent only two survey periods, changes in
estimates between the two time periods do not neces-
sarily reflect a trend. As CDC releases additional survey
results (e.g., 2003-2004), it will become possible to more
fully evaluate trends (CDC, 2002, 2004).
• Generally recognized guidelines for blood levels of
cadmium have not been established.
Data Sources
Data used for this indicator were extracted from the CDC
report that presents results of the ongoing NHANES
(CDC, 2005). The underlying laboratory data supporting
CDC's report are available online in SAS® transport file
format at http://www.cdc.gov/nchs/about/major/nhanes/
datalink.htm.
References
CDC (Centers for Disease Control and Prevention). 2005.
Third national report on human exposure to environmen-
tal chemicals. NCEH publication no. 05-0570.
CDC. 2004. NHANES analytic guidelines. June 2004
version.
CDC. 2002. NHANES 1999-2000 addendum to the
NHANES III analytic guidelines. Updated August 30, 2002.
INDICATOR
Blood Persistent Organic Pollutants Level
Persistent organic pollutants (POPs) are manmade
organic chemicals that remain in the environment for
years or decades. POPs are of special concern because they
often remain toxic for decades or longer after release to
the environment. The more persistent a toxic chemical is,
the greater the probability for human exposure over time.
Because they circulate globally long after being released
into the environment, POPs are often detected in locations
far from the original source (U.S. EPA, 2004a).
One of the major sources of POPs exposure among the
general population is food. Food contamination begins
•with contaminated soil and/or plants, but is of greatest
concern to humans as the POPs move up the food chain
into animals. Because POPs typically accumulate in fatty
tissue and are slow to be metabolized, they bioconcentrate
(i.e., increase in concentration) with each trophic level.
Therefore, foods such as dairy products, eggs, animal fats,
and some types offish are more likely to contain greater
concentrations of POPs than fruits, vegetables, and grains.
POPs have been linked to adverse health effects such as
cancer, nervous system damage, reproductive disorders,
and disruption of the immune system in both humans and
animals (U.S. EPA, 2004a).
This indicator presents data from the Centers for Disease
Control and Prevention's (CDC's) National Health and
Nutrition Examination Survey (NHANES) 1999-2000 and
2001-2002. NHANES is a series of surveys conducted by
CDC's National Center for Health Statistics that is designed
to collect data on the health and nutritional status of the
civilian, non-institutionalized U.S. population using a com-
plex, stratified, multistage, probability-cluster design. CDC's
National Center for Environmental Health conducted the
laboratory analyses for the biomonitoring samples. Begin-
ning in 1999, NHANES became a continuous and annual
national survey; biomonitoring for certain environmental
chemicals also was implemented. These data are presented
here as a baseline, with the intent of reporting trends over
larger time periods in the future. Blood levels of POPs or
their metabolites were measured in NHANES participants
age 12 or older. This indicator includes the following three
broad classes of POPs:
• Organochlorine pesticides
• Polychlorinated dibenzo-p-dioxins (dioxins) and poly-
chlorinated dibenzo-p-furans (furans)
• Polychlorinated biphenyls (PCBs)
Organochlorine pesticides were first introduced in
the 1940s. Because of their environmental persistence, EPA
banned most uses of these chemicals during the 1970s and
1980s. However, many other countries still produce and/or
use organochlorines. These fat-soluble chemicals are most
commonly absorbed through fatty foods. These pesticides
are associated with effects to the central nervous system
at acute exposure levels and potential carcinogenic effects
•with long-term exposure (Reigart and Roberts, 1999).
This indicator includes eight Organochlorine pesticides that
EPA's 2008 Report on the Environment
5-15
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INDICATOR
Blood Persistent Organic Pollutants Level (continued)
Exhibit 5-5. Blood concentrations of selected organochlorine pesticides and metabolites for the U.S.
population age 12 years and older, lipid-adjusted and whole weight, 1999-2002
Geometric mean and selected percentiles
for organochlorine pesticide metabolite concentrations (ng/g)
Survey years Sample size
Aldrin
Lipid-adjusted
Whole weight
Chlordane
Oxychlordane
Lipid-adjusted
Whole weight
trans-Nonachlor
Lipid-adjusted
Whole weight
DDT/DDE
p,p'-DDE
Lipid-adjusted
Whole weight
p,p'-DDT
Lipid-adjusted
Whole weight
o,p'-DDT
Lipid-adjusted
Whole weight
Dieldrin
Lipid-adjusted
Whole weight
Endrin
Lipid-adjusted
Whole weight
See notes at end of table.
2001-2002
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
2001-2002
2001-2002
2001-2002
2001-2002
2,275
2,275
1,661
2,249
1,661
2,249
1,933
2,286
1,933
2,286
1,964
2,298
1,964
2,298
2,305
1,679
2,305
1,669
2,279
1,669
2,279
2,159
2,159
2,187
2,187
Geometric mean
NC
NC
NC
11.4
NC
0.07
18,
17.0
0.11
0.10
260
295
1.54
1.81
NC
NC
NC
NC
NC
^^ NC
NC
NC
NC
NC
NC
50th
-------
INDICATOI
Blood Persistent Organic Pollutants Level (continued)
Exhibit 5-5 (continued). Blood concentrations of selected organochlorine pesticides and metabolites for
the U.S. population age 12 years and older, lipid-adjusted and whole weight, 1999-2002
Geometric mean and selected percentiles
for organochlorine pesticide metabolite concentrations (in ng/g)
Survey years
Sample size
Geometric mean 50tn
75th
90th
95th
Heptachlor
Heptachlor epoxide
Lipid-adjusted 19"-2000
2001-2002
1999-2000
Whole weight
2001-2002
Hexachlorobenzene (HCB)
1999-2000
Lipid-adjusted
| 2001-2002
1999-2000
Whole weight ^^
Mirex
1999-2000
Lipid-adjusted 2001-2002
1999-2000
Whole weight 2001_2002
al\IC = not calculated; the proportion of results
1,589
2,259
1,589
2,259
1,702
2,277
1,702
2,277
1,853
2,257
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
-------
INDICATOR
Blood Persistent Organic Pollutants Level (continued)
Exhibit 5-6. Blood concentrations of selected polychlorinated dibenzo-p-dioxins (dioxins),
polychlorinated dibenzofurans (furans), and dioxin-like polychlorinated biphenyls (PCBs) for the U.S.
population age 20 years and older, lipid-adjusted and whole weight, 1999-2002ab
Geometric mean and selected percentiles
for dioxin, furan, and PCB concentrations
Survey years Sample size
Geometric mean
50th
75th
90th
95th
Dioxins (pg/g)
1,2,3,4, 6,7, 8, 9-OCDD
Lipid-adjusted
Whole weight
1,2,3,4,6,7,8-HpCDD
Lipid-adjusted
Whole weight
1,2,3, 6,7, 8-HxCDD
Lipid-adjusted
Whole weight
Furans (pg/g)
1,2,3,4, 6,7, 8-HpCDF
Lipid-adjusted
Whole weight
PCBs (units vary)
PCB 126 (pg/g)
Lipid-adjusted
Whole weight
PCB 169 (pg/g)
Lipid-adjusted
Whole weight
See notes at end of table.
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1,254
1,171
1,254
1,171
1,237
1,220
1,237
1,220
1,237
1,234
1,237
1,234
1,109
1,219
1,109
1,219
1,238
1,226
1,238
1,226
1,240
1,223
1,240
1,223
NC
346
NC
2.23
NC
39
NC
0.25
NC
34.6
NC
0.22
NC
9.6
NC
0.06
NC
22.7
NC
0.15
NC
17.9
NC
0.12
-------
INDICATOI
Blood Persistent Organic Pollutants Level (continued)
Exhibit 5-6 (continued). Blood concentrations of selected polychlorinated dibenzo-p-dioxins (dioxins),
polychlorinated dibenzofurans (furans), and dioxin-like polychlorinated biphenyls (PCBs) for the U.S.
population age 20 years and older, lipid-adjusted and whole weight, 1999-2002ab
Geometric mean and selected percentiles
for dioxin, furan, and PCB concentrations
Survey years Sample size Geometric mean 50tn 75tn
90th
95th
PCBs (units vary)
PCB138&158(ng/g)
1999-2000 1,261 NC
-------
INDICATOR
Blood Persistent Organic Pollutants Level (continued)
PCBs are chlorinated aromatic hydrocarbons used in
a variety of industries as electrical insulating and heat
exchange fluids. PCBs are composed of mixtures of up
to 209 different chlorinated congeners. U.S. production
of PCBs peaked in the early 1970s; PCBs were banned in
1979. Sources of exposure for the general population include
releases from waste sites and fires involving transformers,
ingestion of foods contaminated by PCBs, and migration
from packaging materials. PCBs typically accumulate in
fatty tissues (ATSDR, 2000).
The detection of PCBs in human blood can reflect either
recent or past exposures. PCBs with higher degrees of chlo-
rination persist in the human body from several months to
years after exposure. Coplanar and mono-ortho substituted
PCBs exhibit health effects similar to dioxins. The human
health effects of PCBs include changes in liver function,
elevated lipids, and gastrointestinal cancers (CDC, 2005).
What the Data Show
Organochlorine Pesticides
Exhibit 5-5 presents the lipid-adjusted and whole weight
geometric means and four percentile values for selected
organochlorine pesticide metabolites measured in blood.
The overall geometric mean forp,p'-DDE (a metabolite for
DDT) during the 1999-2000 survey was 260 nanograms
per gram (ng/g), compared to 295 ng/g in 2001-2002.
During the most recent survey (2001-2002), the geomet-
ric mean for fraws-nonachlor (a component of technical-
grade chlordane) was 17 ng/g, compared with 18.3 ng/g in
1999-2000. Aldrin, dieldrin, endrin, heptachlor epoxide
(the metabolite for heptachlor), HCB, and mirex were
not measured with sufficient frequency above the limit of
detection to calculate a geometric mean.
Geometric mean blood concentrations ofpjj'-DDE were
compared among demographic groups after adjustment
for the covariates of race/ethnicity, age, and gender. For
samples collected between 1999 and 2002, the 12-19 year
age group had less than half the blood p,p'-DDE level com-
pared to the 20 years or older age group (CDC, 2005). The
lipid-adjusted geometric mean level in Mexican Americans
\vas 652 ng/g during the most recent survey, more than
two and one-half times higher than levels in non-Hispanic
•whites and two times higher than levels in non-Hispanic
blacks. It is unknown whether differences in geometric
mean blood p,p'-DDE concentrations between different
age groups or racial/ethnic groups represent differences in
exposure, body size relationships, or metabolism (CDC,
2005) (data not shown).
Dioxins and Furans
In the U.S., quantifiable emissions of dioxin-like com-
pounds from all known sources have decreased by an
estimated 90 percent between 1987 and 2000 (U.S. EPA,
2006). Values reported in NHANES 1999-2000 and
2001-2002 support that estimated decline (CDC, 2005).
For example, among the entire NHANES 1999-2000
sample population, TCDD (generally considered the most
toxic dioxin) was detected less than 1 percent of the time
(CDC, 2003). During 2001-2002, only a small number
of the dioxin and furan congeners analyzed were detected
frequently enough for geometric means to be calculated
(Exhibit 5-6). TCDD continued to be among the list of
congeners analyzed in NHANES 2001-2002, though only
the 95th percentiles for women and non-Hispanic blacks
could be characterized: 6.4 and 7.4 picograms per gram
(pg/g) TCDD lipid-adjusted, respectively (data not shown).
From NHANES 1999-2000, none of the six dioxin or
nine furan congeners measured in the blood were detected
•with sufficient frequency to calculate a geometric mean.
In general, the more highly chlorinated dioxin and furan
congeners were the main contributors to the human body
burden. The higher concentrations of these congeners
in human samples are a result of their greater persistence
in the environment, bioaccumulation in the food chain,
resistance to metabolic degradation, and greater solubility
in body fat (CDC, 2005).
PCBs
During the NHANES 1999-2000 subsample period,
none of the three coplanar and 25 other PCB congeners
•were measured in blood with sufficient frequency above
the limit of detection to calculate a geometric mean. The
frequency of detection of the eight mono-ortho substi-
tuted PCBs ranged from 2 to 47 percent (CDC, 2003).
Coplanar PCB congeners 169 and 126, which exhibit
dioxin-like toxicity, had a detection rate above 5 per-
cent (CDC, 2003). In the 2001-2002 survey, a total of
12 dioxin-like PCB compounds, three coplanar PCBs
and nine mono-ortho-substituted PCBs, were measured
in blood. A total of 25 non-dioxin-like PCBs were also
included in the 2001-2002 NHANES analysis. However,
only two coplanar PCBs and three non-dioxin-like PCB
compounds were detected with sufficient frequency to
calculate a geometric mean (Exhibit 5-6). Although some
PCB congeners were detected with greater frequency dur-
ing the 2001-2002 survey compared to 1999-2000, this
may, in part, be attributed to improved limits of detection
in NHANES 2001-2002 (CDC, 2005). After adjusting for
a number of covariates (e.g., age, gender, blood cotinine,
and lipid level), there were some differences observed in
the concentrations of different PCB congeners between
different demographic subgroups. However, it is unknown
•whether these differences represent differences in exposure,
pharmacokinetics, or the relationship of dose per body
weight (CDC, 2005).
5-20
EPA's 2008 Report on the Environment
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INDICATOI
Blood Persistent Organic Pollutants Level (continued)
Indicator Limitations
• Because the data from NHANES 1999-2000 and
2001-2002 represent only two survey periods, changes in
estimates between the two time periods do not neces-
sarily reflect a trend. As CDC releases additional survey
results (e.g., 2003-2004), it will become possible to more
fully evaluate trends (CDC, 2002, 2004).
• Generally recognized reference levels for organochlo-
rine pesticides and dioxin, furan, and PCB congeners in
blood have not yet been established.
Data Sources
Data used for this indicator were extracted from the CDC
report that presents results of the ongoing National Health
and Nutrition Examination Survey (CDC, 2005). The
underlying laboratory data supporting CDC's report are
available online in SAS® transport file format at http://
www. cdc.gov/nchs/about/major/nhanes/datalink. htm.
References
ATSDR (Agency for Toxic Substances and Disease Reg-
istry). 2000. Toxicological profile for polychlorinated
biphenyls (PCBs). Atlanta, GA: U.S. Department of Health
and Human Services, Public Health Service.
CDC (Centers for Disease Control and Prevention). 2005.
Third national report on human exposure to environmen-
tal chemicals. NCEH publication no. 05-0570.
CDC. 2004. NHANES analytic guidelines. June 2004
version.
CDC. 2003. Second national report on human exposure to
environmental chemicals. NCEH publication 02-0716.
CDC. 2002. NHANES 1999-2000 addendum to the
NHANES III analytic guidelines. Updated August 30, 2002.
IARC (International Agency for Research on Cancer). 1997.
Polychlorinated dibenzo-para-dioxins and polychlorinated
dibenzofurans. IARC Monographs on the Evaluation of
Carcinogenic Risks to Humans vol. 69. Lyon, France.
Reigart, J.R., andJ.R. Roberts. 1999. Recognition and
management of pesticide poisonings. Prepared for U.S.
EPA. Accessed April 11, 2005.
Ritter, L., K.R. Solomon,]. Forget, M. Stemeroff, and C.
O'Leary. n.d. Persistent organic pollutants. Prepared for
the International Programme on Chemical Safety within
the frame-work of the Inter-Organization Programme for
the Sound Management of Chemicals.
U.S. EPA (United States Environmental Protection
Agency). 2006. An inventory of sources and environmen-
tal releases of dioxin-like compounds in the United States
for the years 1987, 1995, and 2000. EPA/600/P-03/002F.
Washington, DC.
U.S. EPA. 2004a. Pesticides: Regulating pesticides-
persistent organic pollutants (POPs). Updated August
2004. Accessed December 7, 2004.
U.S. EPA. 2004b. Hexachlorobenzene. Updated December
2004. Accessed December 7, 2004.
U.S. EPA. 2004c. Mirex. Updated December 2004.
Accessed December 7, 2004.
EPA's 2008 Report on the Environment
5-21
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INDICATOR
Urinary Pesticide Level
Pesticides are chemicals or biological agents that kill
plant or animal pests. They include herbicides, insec-
ticides, fungicides, and rodenticides. More than a billion
pounds of pesticides are used in the U.S. each year to
control weeds, insects, and other organisms that threaten
or undermine human activities (Aspelin, 2003). Some of
these compounds can be harmful to humans if ingested,
inhaled, or other-wise contacted in sufficient quantities.
The primary routes of exposure for the general popula-
tion are ingestion of a treated food source and contact with
applications in or near residential sites. Herbicide expo-
sure can also result from contaminated water. Those who
manufacture, formulate, and/or apply these chemicals can
also be occupationally exposed.
This indicator reports the results of human biomoni-
toring for three classes of non-persistent insecticides and
three classes of herbicides, which can be measured through
metabolites that result from the chemical breakdown of the
pesticide within the body. Measurement of non-persistent
pesticide metabolites in urine typically reflects recent
exposure (i.e., in the last few days) due to the short time
these metabolites remain within the body (CDC, 2005).
The three classes of insecticides covered by this indica-
tor are carbamates, organophosphates, and pyrethroids.
Carbamate insecticides have a wide variety of uses, which
include applications on agricultural crops, residential lawns
and gardens, and golf courses. Carbamate insecticides do
not persist long in the environment, so they have a low
potential for bioaccumulation. Organophosphates are used
to control a broad spectrum of insects. Although organo-
phosphates are still used for insect control on many food
crops, most residential uses are being phased out in the
U.S. Pyrethroids are synthetic analogues of pyrethrins,
•which are natural chemicals found in chrysanthemum
flowers. All three groups are neurotoxicants that act by
overstimulating the nervous systems of exposed organisms.
Symptoms of exposure to pesticides in these classes include
muscle -weakness or paralysis, difficulty breathing, diffi-
culty concentrating, impaired coordination, and memory
loss (CDC, 2005).
The three herbicide classes discussed here are licensed for
both commercial and restricted use. Restricted use products
can only be applied by certified applicators or under the
supervision of such an applicator (U.S. EPA, 2003). The
Exhibit 5-7. Urine concentrations of selected carbamate pesticide metabolites for the U.S. population
age 6-59 years, 1999-2002
Geometric mean and selected percentiles
for carbamate metabolite concentrations
Survey years Sample size
1-Naphthol
ug/L of urine
ug/g of creatinine
2-lsopropoxyphenol
ug/L of urine
ug/g of creatinine
Carbofuranphenol
ug/L of urine
ug/g of creatinine
1999-2000
1999-2000
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1,998
1,998
1,917
2,503
1,917
2,502
1,994
2,530
1,994
2,529
Geometric mean 50tn
1.70 1.22
1.52
NC
NC
NC
NC
NC
NC
NC
NC
1.25
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INDICATOI
Urinary Pesticide Level (continued)
Exhibit 5-8. Urine concentrations of selected organophosphate pesticide metabolites for the U.S.
population age 6-59 years, 1999-2002
Geometric mean and selected percentiles
or organophosphate pesticide metabolite concentrations
Survey years
Dimethylphosphate
ug/L of urine
ug/g of creatinine
Dimethylthiophosphate
ug/L of urine
ug/g of creatinine
Dimethyldithiophosphate
ug/L of urine
ug/g of creatinine
Diethylphosphate
ug/L of urine
ug/g of creatinine
Diethylthiophosphate
ug/L of urine
ug/g of creatinine
Diethyldithiophosphate
ug/L of urine
ug/g of creatinine
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
Sample size
1,949
2,519
1,949
2,518
1,948
2,518
1,948
2,517
1,949
2,518
1,949
2,517
1,949
2,520
1,949
2,519
1,949
2,519
1,949
2,518
1,949
2,516
1,949
2,515
Geometric mean
NC
NC
NC
NC
1.82
NC
1.64
NC
NC
NC
NC
NC
1.03
NC
0.92
NC
NC
0.46
NC
0.45
NC
NC
NC
NC
al\IC = not calculated; the proportion of results below the limit of detection was too high to
b
-------
INDICATOR
Urinary Pesticide Level (continued)
Exhibit 5-9. Urine concentrations of selected pyrethroid pesticide metabolites for the U.S. population age
6-59 years, 2001-2002
Geometric mean and selected percentiles
of pyrethroid pesticide metabolite concentrations
Survey years Sample size Geometric mean 50tn
4-Fluoro-3-phenoxybenzoic acid
ug/L of urine 2001-2002 2,539
ug/g of creatinine 2001-2002 2,538
cis-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid
ug/L of urine 2001-2002 2,539
ug/g of creatinine 2001-2002 2,538
trans-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid
ug/L of urine 2001-2002 2,525
ug/g of creatinine 2001-2002 2,524
cis-3-(2,2-Dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid
ug/L of urine 2001-2002 2,539
ug/g of creatinine 2001-2002 2,538
3-Phenoxybenzoic acid
ug/L of urine 2001-2002 2,539 (
NC
NC
NC
NC
NC
NC
NC
NC
ug/g of creatinine 2001-2002 2,538 0.32
-------
INDICATOI
Urinary Pesticide Level (continued)
metabolites of many organophosphate compounds. Exhibit
5-8 presents the geometric means and four percentile values
for urinary concentrations and creatinine-adjusted urinary
concentrations of these metabolites. Only three of the six
urinary dialkyl phosphates presented (dimethylthiophos-
phate, diethylphosphate, and diethylthiophosphate) were
measured with sufficient frequency above the limit of detec-
tion to calculate a geometric mean. The geometric means
for those metabolites were 1.82 ng/L (1.64 ng/g creatinine),
1.03 ng/L (0.92 ng/g creatinine), and 0.46 ng/L (0.45 ng/L
creatinine), respectively.
Pyrethroids
Pyrethroid (parent and metabolite) compounds were not
included in the NHANES 1999-2000 list of analytes mea-
sured in urine. During the 2001-2002 NHANES, however,
five pyrethroid urinary metabolites were measured in urine
samples from a subgroup of participants. Only one of these
metabolites, 3-phenoxybenzoic acid, was measured with suf-
ficient frequency above the limit of detection to calculate a
geometric mean. The geometric mean concentration of this
metabolite measured in urine was 0.32 ng/L (Exhibit 5-9).
Herbicides
During the 1999-2000 survey, none of the direct metabo-
lites of the three primary classes of herbicide were detected
in urine with sufficient frequency above the limit of detec-
tion to calculate a geometric mean; therefore, data are not
displayed. The metabolites 2,4,5-trichlorophenoxyacetic
acid and atrazine mercapturate were detected in only 1.2
percent and 3.3 percent, respectively, of the subsample
(CDC, 2003). The minor metabolite 2,4-dichlorophenol
had a geometric mean of 1.1 ng/L measured in urine;
however, this metabolite can also be a result of metabolism
of several other chemicals or a byproduct in the manu-
facture of chemicals. The findings from the 2001-2002
survey were generally consistent with earlier findings
showing these metabolites to be frequently near or below
the limits of detection. Unlike the 1999-2000 results,
2,4-dichlorophenol samples collected during 2001-2002
•were not detected with sufficient frequency above the
detection limit to calculate a geometric mean. However,
the reported concentrations of this metabolite at the 75th,
90th, and 95th percentile were higher during the 2001-2002
survey than during the 1999-2000 survey (CDC, 2005).
(Data not shown.)
Indicator Limitations
• Because the data from NHANES 1999-2000 and
2001-2002 represent only two survey periods, changes in
estimates between the two time periods do not necessarily
reflect a trend. As CDC releases additional survey results
(e.g., 2003-2004) it will become possible to more fully
evaluate trends (CDC, 2002, 2004).
• Urine creatinine concentrations were used to adjust the
urinary concentrations of pesticides and metabolites of
pesticides and phthalates in subsets of adults participating
in NHANES. Traditionally, this approach has been used
in population groups without much diversity. How-
ever, the inclusion of multiple demographic groups (e.g.,
children) in NHANES may increase the variability in the
urinary creatinine levels when comparing across these dif-
ferent study populations (Barr et al., 2004).
• Generally recognized reference levels for carbamate,
organophosphate, herbicide, and pyrethroid metabolites
in urine have not yet been established.
• Some metabolites may result from sources other than
pesticide exposure. For example, 1-naphthol in the urine
may reflect multiple sources of exposure, and is therefore
not just an indicator of carbamate pesticide exposure.
Data Sources
Data used for this indicator were extracted from two CDC
publications that present results of the ongoing NHANES
(CDC, 2003, 2005). The underlying laboratory data sup-
porting CDC's report are available online in SAS® trans-
port file format at http://www.cdc.gov/nchs/about/major/
nhanes/datalink.htm.
References
Aspelin, A.L. 2003. Pesticide usage in the United States:
Trends during the 20th century. Raleigh, NC: Center for
Integrated Pest Management, North Carolina State Univer-
sity.
Barr, D.B., L.C. Wilder, S.P. Caudill, AJ. Gonzalez,
L.L. Needham, andJ.L. Pirkle. 2004. Urinary creatinine
concentrations in the U.S. population: Implications for
urinary biological monitoring measurements. Environ.
Health Persp. 113:192-200.
CDC (Centers for Disease Control and Prevention). 2005.
Third national report on human exposure to environmen-
tal chemicals. NCEH publication no. 05-0570.
CDC. 2004. NHANES analytic guidelines. June 2004
version,
CDC. 2003. Second national report on human exposure to
environmental chemicals. NCEH publication 02-0716.
CDC. 2002. NHANES 1999-2000 addendum to the
NHANES III analytic guidelines. Updated August 30, 2002.
EPA's 2008 Report on the Environment
5-25
-------
INDICATOR
Urinary Pesticide Level (continued)
Reigart, J.R., andJ.R. Roberts. 1999. Recognition
and management of pesticide poisonings. Fifth edition.
EPA/735/R-98/003.
U.S. EPA (United States Environmental Protection
Agency). 2003. Restricted use products (RUP) report.
Accessed March 10, 2005.
INDICATO
Urinary Phthalate Level
Phthalates are industrial chemicals added to many con-
sumer products such as food packaging, plastics (plastic
bags, garden hoses, recreational toys, medical tubing, plas-
tic clothes, etc.), adhesives, detergents, personal-care prod-
ucts (such as soap, shampoo, nail polish, etc.), and many
others. Exposure can occur through food that has been in
contact with phthalate containing packaging, as well as
direct contact with products that contain phthalates.
Acute high-dose exposure to di-2-ethylhexyl phthalate,
for example, may be associated with mild gastrointestinal
disturbances, nausea, and vertigo (U.S. EPA, 2005). Chronic
exposure to phthalate compounds has been associated with
damage to the liver and testes, cancer, and birth defects in
animal studies. However, the extent to which these effects
occur in humans is the subject of ongoing research; whether
detected levels in humans are a health concern is not yet
known (CDC, 2005; Kavlock et al, 2002a-g).
This indicator is based on data collected by the National
Health and Nutrition Examination Survey (NHANES).
NHANES is a series of surveys conducted by the Centers
for Disease Control and Prevention's (CDC's) National
Center for Health Statistics that is designed to collect data
on the health and nutritional status of the civilian, non-
institutionalized U.S. population using a complex, strati-
fied, multistage, probability-cluster design. CDC's National
Center for Environmental Health conducted the laboratory
analyses for the biomonitoring samples. Beginning in 1999,
NHANES became a continuous and annual national survey;
biomonitoring for certain environmental chemicals also was
implemented. Metabolites of phthalates are measured in
urine as a biomarker of phthalate exposure in the popula-
tion. Data for 1999-2000 and 2001-2002 are presented here
as a baseline, with the intent of reporting trends across time
as more data become available in the future.
What the Data Show
Exhibit 5-10 presents the geometric means and four per-
centiles for urinary concentrations and creatinine-adjusted
urinary concentrations of 12 selected metabolites of phtha-
lates among a subsample of participants age 6 years and older
from the most current NHANES (2001-2002). Seven of the
12 phthalates were also measured in the 1999-2000 survey
and are also presented in the table. Mono-ethyl phthalate (the
metabolite for diethyl phthalate, an industrial solvent used in
many products including those containing fragrances) was
the phthalate detected in the highest concentration during
both surveys (1999-2000 and 2001-2002), with creatinine-
adjusted geometric mean concentrations of 163 and 167
micrograms per gram (ng/g) of creatinine, respectively.
In addition, other phthalate compounds such as
mono-n-butyl phthalate (a metabolite for dibutyl phtha-
late, an industrial solvent used in cosmetics, printing inks,
insecticides), mono-benzyl phthalate (a metabolite for
benzylbutyl phthalate, an industrial solvent used in adhe-
sives, vinyl flooring, and car care products), and mono-
2-ethyl-hexyl phthalate (a metabolite for di-2-ethylhexyl
phthalate, used to produce flexible plastics) were detected
in urine samples. Mono-cyclohexyl phthalate, mono-
n-octyl phthalate, and mono-isononyl phthalate were
not measured with sufficient frequency above the limit of
detection to calculate a geometric mean for those samples
collected between 1999 and 2002.
During the 1999-2000 and 2001-2002 surveys, the geo-
metric mean levels for mono-ethyl phthalate, mono-n-butyl
phthalate, mono-benzyl phthalate, and mono-2-ethylhexyl
phthalate among specified demographic subgroups were
compared after adjustment for the covariates of race/ethnic-
ity, age, gender, and urinary creatinine. For those age 6-11
years compared to the older age groups (12-19 years and 20+
years), urinary mono-ethyl phthalate levels were found to be
lower, but urinary mono-butyl, mono-benzyl, and mono-2-
ethylhexyl phthalates were higher (CDC, 2005). Females
tended to have a higher level than males for mono-ethyl,
mono-butyl, and mono-benzyl phthalates. Non-Hispanic
blacks had higher levels of mono-ethyl phthalate than non-
Hispanic \vhites or Mexican Americans. (Data not shown.)
Indicator Limitations
• Because the data from NHANES 1999-2000 and
2001-2002 represent only two survey periods, changes in
estimates between the two time periods do not neces-
sarily reflect a trend. As CDC releases additional survey
results (e.g., 2003-2004), it will become possible to more
fully evaluate trends (CDC, 2002, 2004).
5-26
EPA's 2008 Report on the Environment
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INDICATOI
Urinary Phtha I ate Level (continued)
Exhibit 5-10. Urine concentrations of selected phthalate metabolites in the U.S. population age 6 years
and older, 1999-20023
Geometric mean and selected percentiles of
phthalate metabolite concentrations
Survey years
Mono-methyl phthalate
ug/L of urine
ug/g of creatinine
Mono-isobutyl phthalate
ug/L of urine
ug/g of creatinine
Mono-(2-ethyl-5-hydroxyhexyl'
ug/L of urine
ug/g of creatinine
2001-2002
2001-2002
2001-2002
2001-2002
phthalate
2001-2002
2001-2002
Sample size
2,782
2,772
2,782
2,772
2,782
2,772
Geometric mean 50tn
1.15
1.08
2.71
2.53
20.0
18.8
1.50
1.33
2.60
2.44
20.1
16.6
75th
3.30
2.62
5.70
4.50
43.6
32.3
90th
6.00
5.00
11.9
8.02
91.3
70.8
95th
9.80
7.97
17.9
12.0
192
147
Mono-(2-ethyl-5-oxohexyl) phthalate
ug/L of urine
ug/g of creatinine
2001-2002
2001-2002
2,782
2,772
13.5
12.6
14.0
11.2
29.6
21.3
59.9
45.1
120
87.5
Mono-3-carboxypropyl phthalate
ug/L of urine
ug/g of creatinine
Mono-ethyl phthalate
ug/L of urine
ug/g of creatinine
Mono-n-butyl phthalate
ug/L of urine
ug/g of creatinine
Mono-benzyl phthalate
ug/L of urine
ug/g of creatinine
Mono-cyclohexyl phthalate
ug/L of urine
ug/g of creatinine
See notes at end of table.
2001-2002
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
1999-2000
2001-2002
2,782
2,772
2,536
2,782
2,536
2,772
2,541
2,782
2,541
2,772
2,541
2,782
2,541
2,772
2,541
2,782
2,541
2,772
2.75
2.57
179
178
163
167
24.6
18.9
22.4
17.8
15.3
15.1
14.0
14.1
NC
NC
NC
NC
3.00
2.45
164
169
141
147
26.0
20.4
21.9
17.4
17.0
15.7
13.3
13.5
-------
INDICATOI
Urinary Phthalate Level (continued)
Exhibit 5-10 (continued). Urine concentrations of selected phthalate metabolites in the U.S. population
age 6 years and older, 1999-20023
Geometric mean and selected percentiles of
phthalate metabolite concentrations
Survey years
Sample size Geometric mean
50th
75th
90th
95th
Mono-2-ethylhexyl phthalate
ug/L of urine
ug/g of creatinine
1999-2000
2001-2002
1999-2000
2001-2002
2,541
2,782
2,541
2,772
4.27
3.12
3.99
3.20
4.10
3.08
3.89
7.60
9.80
5.88
7.94
14.8
22.8
10.8
18.2
23.8
38.9
18.5
32.8
Mono-n-octyl phthalate
ug/L of urine
ug/g of creatinine
1999-2000
2001-2002
1999-2000
2001-2002
2,541
2,782
2,541
2,772
NC
NC
NC
NC
CDC (Centers for Disease Control and Prevention). 2005.
Third national report on human exposure to environmen-
tal chemicals. NCEH publication no. 05-0570.
5-28
EPA's 2008 Report on the Environment
-------
INDICATOI
Urinary Phtha I ate Level (continued)
CDC. 2004. NHANES analytic guidelines. June 2004
version.
CDC. 2002. NHANES 1999-2000 addendum to the
NHANES III analytic guidelines. Updated August 30, 2002.
U.S. EPA. 2005. Consumer factsheet on: di(2-ethylhexyl)
phthalate. Accessed March 21, 2005.
Kavlock, R., K. Boekelheide, R. Chapin, M. Cunningham,
E. Faustman, P. Foster, et al. 2002a. NTP Center for the
evaluation of risks to human reproduction: Phthalates expert
panel report on the reproductive and developmental toxicity
of di-n-octyl phthalate. Reprod. Toxicol. 16(5):721-734.
Kavlock, R., K. Boekelheide, R. Chapin, M. Cunningham,
E. Faustman, P. Foster, et al. 2002b. NTP Center for the
evaluation of risks to human reproduction: Phthalates expert
panel report on the reproductive and developmental toxicity
of di-n-hexyl phthalate. Reprod. Toxicol. 16(5):709-719.
Kavlock, R., K. Boekelheide, R. Chapin, M. Cunningham,
E. Faustman, P. Foster, et al. 2002c. NTP Center for the
evaluation of risks to human reproduction: Phthalates expert
panel report on the reproductive and developmental toxicity
of di-isononyl phthalate. Reprod. Toxicol. 16(5):679-708.
Kavlock, R., K. Boekelheide, R. Chapin, M. Cunningham,
E. Faustman, P. Foster, et al. 2002d. NTP Center for the
evaluation of risks to human reproduction: Phthalates expert
panel report on the reproductive and developmental toxicity
of di-isodecyl phthalate. Reprod. Toxicol. 16(5):655-678.
Kavlock, R., K. Boekelheide, R. Chapin, M. Cunning-
ham, E. Faustman, P. Foster, et al. 2002e. NTP Center for
the evaluation of risks to human reproduction: Phthalates
expert panel report on the reproductive and developmen-
tal toxicity of di(2-ethylhexyl)phthalate. Reprod. Toxicol.
16(5):529-653.
Kavlock, R., K. Boekelheide, R. Chapin, M. Cunningham,
E. Faustman, P. Foster, et al. 2002E NTP Center for the
evaluation of risks to human reproduction: Phthalates expert
panel report on the reproductive and developmental toxicity
of di-n-butyl phthalate. Reprod. Toxicol. 16(5):489-527.
Kavlock, R., K. Boekelheide, R. Chapin, M. Cunningham,
E. Faustman, P. Foster, et al. 2002g. NTP Center for the
evaluation of risks to human reproduction: Phthalates expert
panel report on the reproductive and developmental toxicity
of butyl benzyl phthalate. Reprod. Toxicol. 16(5):453-487.
5.2.3 Discussion
What These Indicators Say About Trends
in Human Exposure to Environmental
Contaminants
The biomonitoring indicators presented in this section provide
an overall representation of the levels of selected contami-
nants, or metabolites of contaminants, in human blood and
urine across the U.S. population. Measurable levels of many of
these contaminants appear in at least some subset of the popu-
lations tested. Together, these indicators help us understand
the extent to which exposure to individual substances has or
has not occurred on a national scale. As stated previously, the
presence of a contaminant in human tissue does not by itself
mean that the contaminant has caused or will cause adverse
effects in that person.
Lead, mercury, cadmium, persistent organic pollutant metabo-
lites, and cotinine were reported at varying levels in sampled
blood and the metabolites of pesticides and phthalates in the
urine of a subset of those tested. Based on the available data,
some notable changes in blood levels were reported over time,
primarily for the metals. Compared to historical data collected
by the Centers for Disease Control and Prevention (CDC),
blood lead levels have been steadily declining since the 1980s.
The same general observation is true for blood cotinine (see
Section 2.4).
Most blood mercury levels in children and women tested
•were reported below 5.8 micrograms per liter (jag/L)—levels
believed not to be associated with harmful health effects.
However, nearly 6 percent of women tested showed blood
mercury between 5.8 and 58 ng/L. The latter level is consid-
ered a general lower bound for neurological effects in develop-
ing fetuses and children of exposed mothers.9
Current National Health and Nutrition Examination Survey
(NHANES) data sets provide some information about vari-
ability of biomarkers across age, gender, race, or ethnicity.
Such analysis is only possible, however, for those chemicals
frequently measured above the level of detection. For example,
blood lead levels are highest among children; cadmium levels
Centers for Disease Control and Prevention. 2005.Third national report
on human exposure to environmental chemicals. NCEH publication no.
05-0570.
EPA's 2008 Report on the Environment
5-29
-------
are reported highest in the most recent survey in those 20
years and older. Blood mercury levels are reported for children
age 1-5 years and women of child-bearing age only, with the
highest levels reported in the latter group. In most cases where
disparities are observed, it is unknown whether the differences
observed represent differences in exposure, pharmacokinetics
(absorption, distribution, metabolism, and excretion), or the
relationship of dose per body weight.10
|H Limitations, Gaps, and Challenges
Available national-level data provide information on the gen-
eral magnitude of exposures that are occurring for this subset
of contaminants. Further, they serve as a firm foundation
or baseline for future analysis. However, available indicator
data answer only a part of the question. At this point in time,
most of the biomonitoring indicators alone do not (1) enable
an extensive assessment of temporal trends; (2) identify and
explain possible differences among some subpopulations; (3)
provide information on the geographic distribution of the
population of concern, or any particular "hot spots" that may
exist; (4) reveal exposure conditions; (5) provide information
for all contaminants of potential interest; (6) consider expo-
sure to multiple contaminants; or (7) provide perspective as to
•whether measured levels are elevated or likely to cause harm-
ful effects. These are the most notable limitations, challenges,
and data gaps of EPA interest in answering the question of
trends in exposure to environmental contaminants.
Temporal Trends
The relatively short time frame of the indicator data set limits
the analysis of temporal trends, but these indicators can serve
as a baseline for future analysis. Most of the indicators pre-
sented to answer this question reflect data from only one or
two NHANES sampling periods (1999-2000 and 2001-2002).
Only as additional NHANES reports are released every 2
years will meaningful temporal trend analysis be possible.
However, CDC has been monitoring blood lead and cotinine
since approximately 1976; for these contaminants, more mean-
ingful temporal trend analysis is possible.
Subgroup Analysis
The adequacy of data for subgroup evaluations varies by
indicator. The NHANES data sets presented in this chapter
contain a sufficiently large sample size to provide reliable age,
gender, race, and ethnicity subgroup analyses. In some cases,
however, the numbers of observations were insufficient to
meet statistical reliability or confidentiality requirements for
reporting estimates for all race or ethnicity categories.11 The
benefits of such analyses have been demonstrated in earlier
NHANES subgroup comparisons of blood lead levels
(e.g., children age 1-5 years, children living in urban or low-
income areas), which have allowed resources to be targeted to
higher risk or susceptible populations. However, not all ages
are represented for all biomarkers in NHANES. Further, in
cases where a small percentage of samples had detectable con-
centrations of the measured contaminant, subgroup compari-
sons are impossible or less meaningful.
Geographic Trends
The data currently available do not allow for reliable regional
subgroup analyses, because the number of geographic regions
sampled each year is relatively small. Although the NHANES
sampling scheme is designed to obtain a cross-section of data
from various regions across the U.S., the data set is not suffi-
ciently representative to allow inferences about regional levels
of the selected biomonitoring indicators.
Exposure Conditions
Biomonitoring data alone do not provide information on
\vhen or how exposure to a particular contaminant occurred.
Many different exposure scenarios (e.g., acute high expo-
sure versus long-term low-level exposures) can lead to the
same concentration measured in the body. The measure does
not necessarily identify the source (s) of that contaminant or
how a person was exposed (e.g., exposure via drinking water
versus food versus inhalation; environmental versus non-
environmental source). Biomarkers of exposure integrate
exposures across multiple exposure routes. Additional infor-
mation on ambient conditions would be needed to deter-
mine \vhat exposures contribute to concentrations in people's
bodies. For example, lead in children's blood may come from
exposure to airborne sources, contaminated water or food,
or contaminated soil or dust. In addition, some biomarkers
are not specific to a particular contaminant, making inter-
pretation of the data and their significance uncertain. Lastly,
some environmental contaminants are also produced in trace
amounts by normal metabolic processes (e.g., formaldehyde
and acetone), so their presence cannot always be attributed to
external exposure.12'13
Other Environmental Contaminants
There are still many contaminants for which no biomonitor-
ing indicators exist, and others that are simply not feasible to
analyze using current technology or data collection methods.
For example, although it is possible to measure the amount of
radiation that a person is exposed to using a dosimeter, bio-
markers are not yet feasible for national estimates of exposure
to radon. Similar issues of feasibility exist with other con-
taminants, including most criteria air pollutants (e.g., ozone,
nitrogen dioxide, carbon monoxide, and particulate matter),
biological agents (e.g., molds, certain infectious agents such
10 Centers for Disease Control and Prevention. 2005.Third national report
on human exposure to environmental chemicals. NCEH publication no.
05-0570.
11 National Center for Health Statistics. 2006. Health, United States, 2006,
with chartbook on trends in the health of Americans. DHHS publication
no. 2006-1232. Hyattsville, MD Watson, WR, and A. Mutti. 2004. Role of
biomarkers in monitoring exposures to chemicals: Present position, future
prospects. Biomarkers 9(3):211-242.
12 Watson, W.R, and A. Mutti. 2004. Role of biomarkers in monitoring
exposures to chemicals: Present position, future prospects. Biomarkers
9(3):211-242.
13 Bates, M.N., J.W. Hamilton, J.S. LaKind, P. Langenberg, M. O'Malley, andW.
Snodgrass. 2005.Workgroup report: Biomonitoring study design, interpreta-
tion, and communication—lessons learned and path forward. Environ. Health
Perspect. 113(11):1615-1621.
5-30
EPA's 2008 Report on the Environment
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as bacteria or viruses, and dust mites), byproducts from the
disinfection of drinking water (e.g., chlorine or chlorine-
containing compounds), and several contaminants commonly
found in air and drinking water at Superfund sites (e.g.,
trichloroethylene and tetrachloroethylene, among others). In
many cases, biomonitoring for these contaminants is either
cost-prohibitive or not yet technologically feasible. However,
biomonitoring methods are constantly evolving. For example,
CDC has added a number of environmental contaminants to
its biomonitoring efforts, which will be included in future
reports. These include arsenic, polybrominated compounds,
and perfluorinated compounds (e.g., perfluorooctane sulfonate
and perfluorooctanoic acid), among others.14
In addition, researchers continue to evaluate whether certain
chemicals, referred to as endocrine disrupters, may contribute to
adverse health effects in humans and may impact the health of
future generations. Information about the magnitude and pattern
of human exposure to endocrine disrupters is being collected for
only a small subset of chemicals that compose this group (e.g.,
PCBs, DDT and its metabolites); wider testing will be challeng-
ing because there are still many compounds that have not yet
been classified as endocrine disrupters, but may someday be iden-
tified as such. Moreover, understanding the specific window of
vulnerability during different stages of development will be criti-
cal in evaluating the potential harmful effects of these chemicals.
Multiple Contaminants
Current biomonitoring indicators do not consider the effects
of exposures to multiple contaminants. Specifically, biomarker
measurements that are collected in NHANES do not provide
any perspective on how different classes of contaminants interact
•with one another once they enter the body and to what extent
associated responses are additive, antagonistic, or synergistic.
Clinical Reference or Comparison Levels
For most available biomonitoring indicators, no general scien-
tific consensus exists as to how to interpret measured levels of
contaminants in blood and urine. For example, are measured
levels associated with some clinical effect or elevated above
some "safe" or "background" level? Tracking trends in expo-
sure over time, combined with trends in ambient measurements
and health outcome measurements, is a key part of establish-
ing such reference values. Establishing background or refer-
ence ranges (distributions) will help in identifying people with
unusually high exposure or the percentage of the populations
•with contaminant exposures above established levels of concern.
5.3 What Are the Trends
in Health Status in the
United States?
5.3.1 Introduction
An overarching goal of public health agencies is to increase
quality and years of healthy life and to eliminate health dis-
parities. Tracking historical trends in general health status can
help identify where interventions have improved the health
of a population or where interventions may be needed (e.g.,
exploring causative factors and preventive measures). For
example, a key concern for EPA is what possible environmen-
tal exposures could be contributing to the diseases or condi-
tions that are the leading causes of death in the U.S.
The topics covered under this question are broad and not
intended to represent specific diseases or conditions related
to the environment. Environmental contaminants from air,
•water, and land can influence the overall health of a nation.
As described in Section 5.1, however, many factors other than
the environment influence the health of a population, such
as socio-demographic attributes, behavioral and genetic risk
factors, level of preventive care, and quality of and access to
health care. Though no consensus exists on the relative con-
tribution of environmental exposures, tracking overall health
in the U.S. provides important context for the next section of
this chapter, which examines specific acute and chronic dis-
eases and conditions that may be linked more specifically with
exposures to environmental contaminants.
As defined by the World Health Organization, health is a state
of complete physical, mental, and social well-being, and not
the mere absence of disease or infirmity.15 The health status of
a population can be measured by a wide range of factors: birth
and death rates, life expectancy, quality of life, morbidity
from specific diseases, risk factors, use of ambulatory care and
inpatient care, accessibility of health personnel and facilities,
financing of health care, health insurance coverage, and many
other factors.16
While no single set of measures can completely characterize
the health of a large and diverse population, CDC and other
health agencies worldwide consistently have viewed life expec-
tancy and mortality data as indicators of overall population
health because they represent the cumulative effects of social
and physical environmental factors, behavioral and genetic risk
factors, and the level and quality of health care. These data
include the leading causes of mortality (among both infants and
Department of Health and Human Services. 2003. Candidate chemicals for
possible inclusion in future releases of the national report on human exposure to
environmental chemicals. Federal Register 68(189)56296-56298. September 30.
World Health Organization. 1946. Preamble to the constitution of the World
Health Organization as adopted by the International Health Conference,
New York, 19-22 June, 1946;signed on 22 July 1946 by the representatives of
61 states (Official Records of the World Health Organization, no. 2, p. 100)
and entered into force on 7 April 1948.
U.S. Department of Health and Human Services. 2000. Healthy people 2010:
Understanding and improving health. Second edition.Washington, DC: US.
Government Printing Office,
EPA's 2008 Report on the Environment
5-31
-------
the general population), which provide a broad perspective on
the diseases and conditions that are having the greatest impact
on the nation's health. Infant mortality is a particularly useful
measure of health status, because it indicates both the current
health status of the population and predicts the health of the
next generation.17 It reflects the overall state of maternal health
as \vell as the quality and accessibility of primary health care
available to pregnant women and infants.
Tracking health status using such indicators provides informa-
tion on changing or emerging trends. At the beginning of the
20th century, the population of the U.S. was characterized by a
low standard of living, poor hygiene, and poor nutrition; com-
municable diseases and acute conditions were major causes of
most premature deaths. Over the course of the century, public
health measures such as improved sanitation and drinking
•water treatment led to a dramatic decrease in deaths due to
infectious diseases and a marked increase in life expectancy.
As the population has aged, chronic diseases such as heart
disease and cancer have become the leading causes of death.18
These diseases may require a different approach to prevention,
detection, and treatment compared to the infectious and acute
illnesses more common in the past.
5.3.2 ROE Indicators
Other agencies such as CDC routinely assess the state of the
nation's health. EPA has drawn on the comprehensive data
collection efforts and assessments conducted by these agencies
in addressing this question. Three indicators are used to assess
the trends in health status in the U.S. (Table 5-3). Life expec-
tancy at birth is the number of years a newborn would expect to
live if that person experienced the mortality schedule existing
at the time of birth. Infant mortality is the number of infants
\vho die before their first birthday. General mortality represents
the number of all deaths nation-wide and provides information
on the leading causes of death. Mortality is also tracked using
years of potential life lost, or the number of years "lost" by
people in a population who die prematurely of a stated cause.
These indicators are interrelated—e.g., declines in mortality
result in increased life expectancy, and shifts in life expectancy
are often used to describe changes in mortality; changes in
infant mortality are reflected in general mortality as well.
Where possible, the indicators for this question track health
status among subpopulations (e.g., by gender, race, ethnic-
ity). Generally, differences in mortality and life expectancy
between black and white Americans have been tracked for
the past several decades, in some cases as far back as the 1930s.
A broader spectrum of race and ethnic group breakdowns is
available for these indicators in more recent years, including
American Indian/Alaska Native, Asian or Pacific Islander,
and Hispanic origin. Subpopulation data are presented to
the extent practicable under "What the Data Show" and/or
•within indicator exhibits.
Table 5-3. ROE Indicators of Trends in Health Status in the United States
National Indicators
General Mortality
Life Expectancy at Birth
Infant Mortality
Section
5.3.2
5.3.2
5.3.2
5-33
5-35
5-36
National Center for Health Statistics. 2001. Healthy people 2000 final review.
Hyattsville, MD: Public Health Service,
Ibid.
5-32
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INDICATOI
General Mortality
Overall mortality is a key measure of health in a popu-
lation. Three measures of mortality are "all cause"
mortality, cause-specific mortality, and years of potential
life lost (YPLL). "All cause" mortality counts the total
number of deaths due to any cause within a specified year,
\vhereas cause-specific mortality statistics count the num-
ber of deaths due to a particular cause in a specified year.
YPLL is defined as the number of years between the age
at death and a specified age; that is, the total number years
"lost" by persons in the population who die prematurely of
a stated cause. Ranking the causes of death can provide a
description of the relative burden of cause-specific mortal-
ity (NCHS, 2005).
This indicator is based on mortality data recorded in the
National Vital Statistics System, which registers virtually
all deaths nation-wide from death certificate data. YPLL is
calculated by subtracting the age at death from a selected
age (e.g., 65, 75, 85), then summing the individual YPLLs
across each cause of death (CDC, 2007). Sixty-five was
selected as the age for this indicator to focus on deaths
more likely to be attributable to preventable causes and less
influenced by increasing age. The temporal coverage of the
data is from 1933 to 2004 and data are collected from all 50
states and the District of Columbia.
What the Data Show
An increase in the number of deaths in the U.S. has been
observed over the last few decades, reflecting the increase
in the size and aging of the population. However, the age-
adjusted all cause mortality rates have declined yearly since
1980 (except in years of influenza outbreaks in 1983, 1985,
1988, 1993, and 1999) with the most recent available rate
of 800.8 deaths per 100,000 people in 2004. Exhibit 5-11
provides some historical perspective on trends in the age-
adjusted mortality rates between 1940 and 2003, showing
that age-adjusted rates were nearly twice as high in 1940
as they were in 2000. The largest decline in "all cause"
mortality rates since 1990 has occurred among black males
compared with white males and black and white females.
The rank order of the leading causes of death has
remained generally the same since 1999. The one differ-
ence is Alzheimer's disease, which was the eighth leading
cause of death between 1999 and 2003 but became the
seventh leading cause in 2004, displacing influenza and
pneumonia. Exhibits 5-12 and 5-13 present the leading
causes of mortality and YPLL for 2004, respectively. The
three leading causes of death were heart disease, cancer,
and stroke, accounting for about 60 percent of all deaths.
The YPLL ranking is different, with unintentional injuries,
cancer, and heart disease as the leading three causes.
During 2004, heart disease was the leading cause of
death across the reported racial and ethnic groups, except
for Asians or Pacific Islanders for whom cancer (malignant
neoplasms) was the leading cause of death. In addition,
Exhibit 5-11. Age-adjusted "all cause" mortality
rates in the U.S., 1940-2004ab
2,500
2,000
1,500
"? S 1,000
-------
INDICATOR
General Mortality (continued)
in part on unpublished work tables, avail-
able on the NCHS Web site at http://www.
cdc.gov/nchs/deaths.htrn. Leading cause
of death and YPLL data were extracted
from CDC's Web-Based Injury Statistics
Query and Reporting System (WISQARS)
(CDC, 2007) (http://www.cdc.gov/
ncipc/wisqars/). The underlying data in
WISQARS come from CDC/NCHS
annual mortality data files.
References
CDC (Centers for Disease Control and Pre-
vention). 2007. National Center for Injury
Prevention and Control. Web-Based Injury
Statistics Query and Reporting System
(WISQARS) [online]. Leading causes of
death and years of potential life lost (YPLL)
reports, 1999-2004. Accessed October 2,
2007.
CDC. n.d. CDC WONDER: Help page for
compressed mortality file. Accessed Octo-
ber 2007.
NCHS (National Center for Health Sta-
tistics). 2007. Deaths: Final data for 2004.
National Vital Statistics Reports 55(19).
NCHS. 2005. Deaths: Leading causes for
2002. National Vital Statistics Reports
53(17).
NCHS. 2001. Age-adjusted death rates;
trend data based on the year 2000 standard
population. National Vital Statistics Reports
49(9).
Exhibit 5-1 2. Leading causes of death
Number
Cause of death of deaths
Heart disease 652,486
Cancer (malignant neoplasms) 553,888
Stroke (cerebrovascular) 150,074
Chronic lower respiratory diseases 121 ,987
Accidents (unintentional injuries) 112,012
Diabetes mellitus 73,138
Alzheimer's disease 65,965
Influenza and pneumonia 59,664
Nephritis 42,480
Septicemia 33,373
All other causes 532,548
aTotals may not add to 100% due to rounding.
Data source: CDC, 2007
in the U.S. ,2004
Percent of all deaths3
27.2
• 23.1
6.3
• 5.1
• 4.7
• 3.1
|2.8
• 2.5
• 1.8
11.4
• 22.2
Exhibit 5-13. Years of potential life lost
in the U.S., 2004
Cause of death YPLL
Accidents (unintentional injuries) 2,219,044
Cancer (malignant neoplasms) 1 ,877,690
Heart disease 1,413,158
Perinatal period 922,191
Suicide 687,395
Homicide 565,979
Congenital anomalies 486,853
HIV 261,784
Stroke (cerebrovascular) 245,074
Liver disease 231,132
All other causes 2,702,330
aTotals may not add to 100% due to rounding.
Data source: CDC, 2007
(YPLL) before age 65
Percent of all YPLLa
^^^^^•19.1
16.2
12.2
• 7.9
|5.9
4.9
• 4.2
• 2.3
• 2.1
|2.0
• 23.3
5-34
EPA's 2008 Report on the Environment
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INDICATOI
Life Expectancy at Birth
Life expectancy at birth is often used to appraise the
overall health of a given population (NCHS, 2006a).
Changes in life expectancy over time are commonly used
to describe trends in mortality. Life expectancy is the aver-
age number of years at birth a person could expect to live
if current mortality trends were to continue for the rest of
that person's life.
This indicator is based on data from the National Vital
Statistics System, which registers virtually all deaths and
births nation-wide. The temporal coverage of the data is
from 1933 to 2004 and data are collected from all 50 states
and the District of Columbia.
What the Data Show
Exhibit 5-14 presents the historical trends in life expec-
tancy at birth for the entire population as well as by gender
and race (black and white) between 1940 and 2004, show-
ing an upward trend in life expectancy in the U.S. over
time. Life expectancy at birth has increased throughout the
20th and now into the 21st century. The overall life expec-
tancy was the highest ever reported in 2004 at 77.8 years,
increasing from 77.4 in 2003.
Life expectancy continues to increase for both males
(73.9 years in 1999 to 75.2 years in 2004) and females
(79.4 years in 1999 to 80.4 years in 2004). The gap in life
expectancy between males and females widened from 2.0
years to 7.8 years between 1900 and 1979. Recently, this
gap narrowed for the year 2000 (a difference of 5.4 years
between males and females) and remained relatively con-
stant through 2004 (a difference of 5.2 years between males
and females). (Data not shown.)
The increase in life expectancy among blacks reported
for 1999 (71.4 years) continued, with a reported life expec-
tancy of 73.1 years in 2004. The difference in life expec-
tancy between the black and white populations was 5.2
years in 2004. In 2004, white females continued to have
the highest life expectancy at 80.8 years, followed by black
females at 76.3 years, white males at 75.7 years, and black
males at 69.5 years (Exhibit 5-14).
Indicator Limitations
• Life expectancy at birth is strongly influenced by infant
and child mortality rates. It is important to consider such
influences when making comparisons among subgroups,
since differences in life expectancy among certain
subgroups may be mostly attributed to differences in
prenatal care and other important determinants of infant
and child mortality.
Data Sources
The annual life expectancy data used for this indicator were
obtained from life tables published by CDC's National
Center for Health Statistics (NCHS, 2006b). NCHS also
Exhibit 5-14. Life expectancy in the U.S. by
race and sex, 1940-2004
'50 '60 70
Year
Data source: NCHS, 2006b, 2007
'90
'00
publishes life expectancy data in its annual "deaths: final
data" reports (e.g., NCHS, 2007); however, these reports
generally provide year-by-year breakdowns beginning in
1975. NCHS life table reports provide annual data back to
before 1940. Life table methodologies used to calculate life
expectancies are presented in each of these NCHS reports.
References
NCHS (National Center for Health Statistics). 2006a.
Health, United States, 2006, with chartbook on trends
in the health of Americans. DHHS Publication No.
2006-1232. Hyattsville, MD.
NCHS. 2006b. United States life tables, 2003. National
Vital Statistics Reports 54(14). Table 12.
NCHS. 2007. Deaths: Final data for 2004. National Vital
Statistics Reports 55(19). Table 8.
EPA's 2008 Report on the Environment
5-35
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INDICATOI
Infant Mortality
Infant mortality is a particularly useful measure of health
status because it both indicates current health status of the
population and predicts the health of the next generation
(NCHS, 2001). Infant mortality in the U.S. is defined as
the death of an infant from time of live birth to the age of
1 year. It does not include still births. Overall infant mor-
tality is composed of neonatal (less than 28 days afterbirth)
and postneonatal (28 days to 11 months afterbirth) deaths.
This indicator presents infant mortality for the U.S.
based on mortality data from the National Vital Statistics
System (NVSS) based on death certificate data. The NVSS
registers virtually all deaths and births nation-wide, with
data coverage from 1933 to 2004 and from all 50 states and
the District of Columbia.
What the Data Show
In 2004, a total of 27,936 deaths occurred in children under
1 year of age, 89 fewer deaths than in 2003. Exhibit 5-15
presents the national trends in infant mortality between
1940 and 2004 for all infant deaths as well as infant deaths
by gender and race (black and white). A striking decline
has occurred during this time period, with overall infant
mortality rates dropping from nearly 50 deaths per 1,000
live births in 1940 to just under seven deaths per 1,000 live
births in 2004. Beginning around 1960, the infant mortal-
ity rate has decreased or remained level each successive year
through 2004, except for 2002. From 2000 to 2004, infant
mortality rates ranged from 6.8 (2001 and 2004) to nearly
7.0 (2002) per 1,000 live births. Infant mortality rates were
highest among black males and lowest among white females,
although this gap has been decreasing over time.
The infant mortality rate for blacks decreased from 14.6
per 1,000 live births in 1999 to 13.8 per 1,000 live births in
2004. However, this is still twice the rate compared to white
infants, which ranged from approximately 5.7 to 5.8 per
1,000 live births between 1999 and 2004. Infant mortality
rates among Hispanic infants have changed little since 1999.
In 2004, the infant mortality rate for Hispanic infants was
5.6 per 1,000 live births (NCHS, 2007a). (Data not shown.)
In the U.S. in 2004, the 10 leading causes of infant mor-
tality accounted for nearly 69 percent of all infant deaths,
•with the subgroup consisting of congenital anomalies (i.e.,
congenital malformations, deformations, and chromosomal
abnormalities) having the highest rate at nearly 1.4 per 1,000
live births. This category alone accounts for approximately
20 percent of all infant deaths in 2004 (Exhibit 5-16).
Congenital anomalies were generally ranked highest
among the different racial groups. However, the leading
cause of infant mortality among blacks was short gesta-
tion and low birth-weight, followed by congenital anoma-
lies. There were few differences in the leading causes of
infant mortality between Hispanics and non-Hispanics.
In addition, the Centers for Disease Control and Preven-
tion (CDC) report a substantial difference in the leading
Exhibit 5-15. Infant mortality rates in the U.S.
by race and sex, 1940-2004ab
s.
oo
aRace was reported based on the race of the
child (1940-1979) or the race of the mother
(1980-2004).
bAnnual infant mortality rates are not available
prior to 1975 in published sources. Trends
presented from 1940-1974 are based on data
published for 1940,1950,1960, and 1970.
Data source: NCHS, 2007
causes of death during the neonatal versus the postneona-
tal periods. Disorders related to short gestation and low
birth-weight -were the leading cause of death for neonates
and sudden infant death syndrome -was the leading cause
of death for postneonates, based on 2003 data (NCHS,
2007b). (Data not shown.)
Indicator Limitations
Cause of death rankings denote the most frequently
occurring causes of death among those causes eligible
to be ranked. The rankings do not necessarily denote
the causes of death of greatest public health importance.
Further, rankings of cause-specific mortality could change
depending on the defined list of causes that are considered
and, more specifically, the types of categories and subcat-
egories that are used for such rankings (NCHS, 2005).
Mortality rates are based on underlying cause of death as
entered on a death certificate by a physician. Incorrect
coding and low rates of autopsies that confirm the cause
of death may occur. Additionally, some individuals may
have had competing causes of death. "When more than
one cause or condition is entered by the physician, the
underlying cause is determined by the sequence of con-
ditions on the certificate, provisions of the ICD [Interna-
tional Classification of Diseases], and associated selection
rules and modifications" (CDC, n.d.). Consequently,
some misclassification of reported mortality might occur
as a result of these uncertainties, as -well as the underre-
porting of some causes of death.
5-36
EPA's 2008 Report on the Environment
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INDICATOI
Infant Mortality (continued)
Exhibit 5-16. Leading causes of infant death in the U.S., 2004a
Cause of death
Congenital malformations, deformations, and chromosomal abnormalities
Disorders related to short gestation and low birthweight
Sudden infant death syndrome (SIDS)
Newborn affected by maternal complications of pregnancy
Accidents (unintentional injuries)
Newborn affected by complications of placenta, cord, and membranes
Respiratory distress of newborn
Bacterial sepsis of newborn
Neonatal hemorrhage
Circulatory system disease
All other causes
31.2
a"lnfant deaths" are those occurring before the age of 1.
bTotals may not add to 100% due to rounding.
Data source: CDC, 2007
Data Sources
Infant mortality data were obtained from a published
report by CDC's National Center for Health Statistics
(NCHS, 2007a), which provides annual natality data back
to 1975 and decadal data for 1940, 1950, 1960, and 1970.
Data in the NCHS report are based in part on unpublished
work tables, available on the NCHS Web site at http://
www.cdc. gov/nchs/deaths. htm. Leading cause of infant
death data were extracted from CDC's Web-Based Injury
Statistics Query and Reporting System (WISQARS)
(CDC, 2007) (http://www.cdc.gov/ncipc/wisqars/), with
supporting documentation from NVSS reports (NCHS,
2007). The underlying data in WISQARS come from
CDC/NCHS annual mortality data files.
References
CDC (Centers for Disease Control and Prevention).
2007. National Center for Injury Prevention and Control:
Web-Based Injury Statistics Query and Reporting System
(WISQARS) [online]. Leading causes of death reports,
1999-2004. Accessed October 8, 2007.
CDC. n.d. CDC WONDER: Help page for compressed
mortality file. Accessed October 2007.
NCHS (National Center for Health Statistics). 2007.
Deaths: Final data for 2004. National Vital Statistics
Reports 55(19).
NCHS. 2005. Deaths: Leading causes for 2002. National
Vital Statistics Reports 53(17).
NCHS. 2001. Healthy people 2000 final review.
Hyattsville, MD: Public Health Service.
EPA's 2008 Report on the Environment
5-37
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5.3.3 Discussion
What These Indicators Say About Trends in
Health Status in the United States
ROE indicators used to answer this question show that the
overall health of the nation has continued to improve. The
three leading causes of death across all age groups—heart
disease, cancer, and stroke—remain unchanged since 1999.
In contrast, a ranking by years of potential life lost, which
•weighs deaths at an earlier age more heavily, places unin-
tentional injuries, cancer, and heart disease as the top three
(General Mortality indicator, p. 5-33). Although men and
•women in many other countries have longer life expectan-
cies, general mortality rates in the U.S. continue to decline,
and life expectancy continues a long-term upward trend
(Life Expectancy indicator, p. 5-35). See Box 5-2 for an
overview of health status in the U.S. compared to the rest of
the \vorld.
The decline in the all cause mortality rate since 1940 has been
driven largely by declines in deaths from heart disease, stroke,
and unintentional injuries. These trends have been linked in
part to the resources devoted to health education, public health
programs, health research, and health care, and the impact
of these efforts on controlling disease. For example, public
campaigns about smoking and the use of cholesterol-lowering
drugs have contributed to a decline in the death rate from heart
disease. Efforts to improve motor vehicle safety as well as safety
in homes and -workplaces have helped to lower death rates from
unintentional injuries. New medical treatments have resulted in
a decline in the death rate from HIV.19
Infant Mortality (p. 5-36), like the other two indica-
tors, shows a long-term decline, likely due to -widespread
application of advances in medical knowledge (such as the
introduction of synthetic surfactant for preterm infants and
•widespread public education about infant sleep position).20
However, infant mortality in the U.S. remains among the
highest in the industrialized world. In 2003 and 2004, the
infant mortality rates decreased after increasing in 2002 for
the first time since 1958. The 2002 rise in infant mortality
•was attributed to an increase in neonatal deaths (infants less
than 28 days old), particularly deaths of infants within the
first \veek of life.21
Despite a generally improving picture of the nation's health,
racial and ethnic disparities in health status persist. For example,
though the nation's infant mortality rate has decreased, the
infant death rate for black infants is still more than double that
of \vhites. In 2004, the gap in life expectancy between the black
and white populations is 5.2 years, though this gap has been
narrowing.22 Differences in death rates also exist between black
and white populations. Observed differences are believed to be
the result of a complex interaction of genetic variations, envi-
ronmental factors, and specific health behaviors.23
The folio-wing comparisons are based on the most current
statistics for each of the three indicators used to study U.S.
health status. The World Health Organization (WHO)
calculates its statistics to ensure comparability across data
sets; the statistics may not fully match those generated by
individual countries and reported in other reports.
Life expectancy: According to the WHO, in 2004, the
U.S. ranked 35th in terms of life expectancy for males and
females of the 192 WHO member states.1 Japan reports the
highest life expectancy (82 years, compared to the US life
expectancy of 78 years reported by WHO).
Leading causes of death: The leading causes of death
reported in the U.S. continue to be heart disease, cancer,
World Health Organization. 2006. World Health Report. See Statistical Annex
Table 1.
World Health Organization. 2005. Incidence, prevalence, mortality,YLL,
YLD and DALYs by sex, cause and region, estimates for 2002 as reported
in the World Health Report 2004.
and stroke. World-wide, as reported for 2002, cardiovascular
diseases accounted for the largest percentage of deaths, fol-
io-wed by infectious and parasitic diseases and cancer.b
Infant mortality: In 2003, the United States ranked 28th
among the 37 countries, territories, cities, or geographic
areas -with at least 1 million population considered to have
completed counts of live births and infant deaths as indi-
cated in the United Nations Demographic Yearbook.0 The
U.S. infant mortality rate for the same time period (6.9 per
1,000 live births) -was approximately 2 to 3 times higher
than the lowest rates reported -world-wide (e.g., in Hong
Kong the rate -was 2.3, in Singapore 2.5, in Japan 3.0, and in
Sweden 3.1, per 1,000 live births).
National Center for Health Statistics. 2006. Health, United States, 2006,
with chartbook on trends in the health of Americans. Hyattsville, Mary-
land. DHHS Publication No. 2006-1232.Table 25.
National Center for Health Statistics. 2006. Health, United States, 2006.
with chartbook on trends in the health of Americans. DHHS publication no.
2006-1232. Hyattsville, MD. p. 3.
National Center for Health Statistics. 2001. Healthy people 2000 final review.
Hyattsville, MD: Public Health Service, p. 206.
21 National Center for Health Statistics. 2005. Health, United States, 2005,
with chartbook on trends in the health of Americans. DHHS publication no.
2005-1232. Hyattsville, MD. p. 66.
22 Ibid. pp. 11-12.
23 U.S. Department of Health and Human Services. 2000. Healthy people 2010:
Understanding and improving health. Second edition.Washington, DC: US.
Government Printing Office,
5-38
EPA's 2008 Report on the Environment
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Differences also exist between men and women. Based on 2004
data, men have a life expectancy 5.2 years less than that of
•women and have higher death rates for each of the 10 leading
causes of death. However, women have shown increased death
rates over the past decade in areas where men have experienced
improvements, such as lung cancer.24
Limitations, Gaps, and Challenges
The indicators are important and widely accepted measures
of population health status. However, the selected indicators
cannot be expected to fully answer the question on trends in
general U.S. health status. Limitations and information gaps
are highlighted here.
The indicators provide a broad measure of health status and
include many variables that are not related to the environ-
ment. No conclusions, therefore, can or should be drawn
about the role of exposure to environmental contaminants
using these indicators alone. While declining mortality rates
and increasing life expectancy suggest improving health status,
these indicators do not address other aspects of health, such as
morbidity, perceived well-being, or quality of life.
The use of mortality data presents some limitations, largely
related to uncertainties associated with the use of death cer-
tificate data. First, correct coding of the underlying cause of
death and confirmation by autopsy may not occur. Second,
uncertainties in intercensal population estimates can affect
conclusions about trends in data sets. In addition, improved
data on the health status of population subgroups—particularly
across race and ethnic groups—would allow better character-
ization of potential trends across different groups. Accurate
identification of health disparities will require improved data
collection and the use of standardized data. For example,
problems of race and Hispanic-origin classification can affect
Hispanic death rates and the comparison of rates across the
Hispanic and non-Hispanic populations.25
5.4 What Are the Trends
in Human Disease
and Conditions for
Which Environmental
Contaminants May Be
a Risk Factor, Including
Across Population
Subgroups and
Geographic Regions?
5.4.1 Introduction
As discussed throughout this report, numerous human diseases
and conditions have been linked with exposures to environmen-
tal contaminants, some more strongly than others. Identifying
diseases that might be associated with environmental con-
taminants, and determining the existing data sources available
for them, is a key part of the effort to better characterize links
between environmental exposures and adverse health outcomes.
Tracking overall rates of disease in the nation, independent
of exposure, enables the evaluation of disease patterns and
emerging trends. It may identify diseases, conditions, and
possible risk factors that warrant further study or interven-
tion and can help identify where policies or interventions have
been successful. Because the U.S. has a diverse population, an
important component of such an analysis is identifying dispar-
ities among people of differing races and ethnicities, genders,
education and income levels, and geographic locations.
EPA has selected those human diseases and conditions with
•well-established associations with exposures to environmental
contaminants and for which national data are available, recog-
nizing again that in most cases risk factors are multi-factorial
and that the development of a particular disease or condition
depends on the magnitude, duration, and timing of the expo-
sure. The diseases and conditions addressed in this question
are associated with the contaminant sources covered by the
questions in the three media chapters (Chapters 2, 3, and 4) of
this report. As described in Section 5.1, however, this question
is not intended to tie human diseases and conditions to specific
changes in the environment being measured at the national
level. Covered health outcomes fall into the following five
broad categories: cancer, cardiovascular disease, respiratory
24 National Center for Health Statistics. 2006. Health, United States, 2006,
with chartbook on trends in the health of Americans. DHHS publication no.
2006-1232. Hyattsville, MD. pp. 11-12.
25 National Center for Health Statistics. 2006. Deaths: Final data for 2003.
NationalVital Statistics Reports 54(13).
EPA's 2008 Report on the Environment
5-39
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disease, infectious disease, and birth outcome. The reasons for
the inclusion of each are highlighted below.
Cancer
The term "cancer" refers to diseases in which abnormal cells
divide without control, losing their ability to regulate their own
growth, control cell division, and communicate with other cells.
Cancer is the second leading cause of death in the U.S. (General
Mortality indicator, p. 5-33). More than one in three people
•will develop cancer and nearly one in four will die of it.26'27 In
response, scientists continue to explore the role that the expo-
sure to environmental contaminants may play, along with other
possible risk factors, in the initiation and development of cancer.
Some environmental contaminant exposures are known risk
factors for certain types of cancers. Examples include radon and
lung cancer and arsenic and skin cancer. Though many types of
cancer are suspected of being related to ambient environmental
exposures, associations are not always clear because the etiology
of cancer is complex and influenced by a wide range of factors.
Many factors can increase individual cancer risk, such as age,
genetics, existence of infectious diseases, and socioeconomic fac-
tors that can affect exposure and susceptibility.
Childhood cancers are dissimilar from cancers in adults and
are therefore tracked separately. They affect different anatomic
sites and may be of embryonic origin. Though overall cancer
incidence rates are lower in children than in adults, childhood
cancers are the third leading cause of death in children age
1-19 years.28 Children may be particularly susceptible to expo-
sures in utero or during early childhood because their systems
are rapidly developing and affected by evolving hormonal
systems.29 As with many adult cancers, the causes of childhood
cancers are unknown for the most part; environmental influ-
ences may be a factor and have been the subject of extensive
research. Environmental exposures are difficult to evaluate
because cancer is rare in children and because of challenges in
identifying past exposure levels, particularly during potentially
important time periods such as in utero or maternal exposures
prior to conception.30
Cardiovascular Disease
More than one-fourth of the U.S. population lives with a
cardiovascular disease, with more than 6 million hospitaliza-
tions each year.31 Coronary heart disease and stroke, two of
the major types of cardiovascular disease, rank as the first and
third leading causes of death, respectively (General Mortality
indicator, p. 5-33), and are leading causes of premature and
permanent disabilities. Known risk factors include smoking,
high blood pressure, high blood cholesterol, diabetes, physi-
cal inactivity, and poor nutrition. Outdoor air pollution and
environmental tobacco smoke are also known risk factors for
cardiovascular disease. Particulate matter, for example, has
been demonstrated to be a likely causal factor in both cardio-
vascular disease morbidity and mortality. Collective evidence
from recent studies suggests excess risk associated with short-
term exposures to particulate matter and hospital admissions
or emergency department visits for cardiovascular effects.32'33
Environmental tobacco smoke has been shown to be a risk
factor for coronary heart disease morbidity and mortality and
may contribute to stroke, though evidence is more limited.34'35
Respiratory Disease
Chronic obstructive pulmonary disease (COPD) and asthma
are two prevalent chronic respiratory diseases in the U.S.
Epidemiological and clinical studies have shown that ambi-
ent and indoor air pollution are risk factors in several respira-
tory health outcomes, including reported symptoms (nose
and throat irritation), acute onset or exacerbation of existing
disease (e.g., asthma), and deaths.36'37 The relationship between
environmental tobacco smoke and diseases of the respiratory
tract has been studied extensively in humans and in animals;
environmental tobacco smoke has been shown to produce a
variety of upper and lower respiratory tract disorders.38
American Cancer Society. 2005. Cancer facts and figures 2005. Atlanta.
National Toxicology Program. 2004. Report on carcinogens. Eleventh edi-
tion. U.S. Department of Health and Human Services, Public Health Service.
National Center for Health Statistics. 2004. Deaths: Final data for 2002.
National Vital Statistics Reports 53(5).
Anderson, L.M., B.A. Diwan, NT. Fear, and E. Roman. 2000. Critical
windows of exposure for children's health: Cancer in human epidemiologi-
cal studies and neoplasms in experimental animal models. Environ. Health.
Perspect. 108(Suppl 3):573-594.
National Cancer Institute. 2005. National Cancer Institute research on
childhood cancers. Accessed November 2007.
Centers for Disease Control and Prevention. 2005. Preventing heart disease
and stroke. Addressing the nation's leading killers—at a glance. Revised
August 2005.
U.S. Environmental Protection Agency. 2005. Review of the National Ambi-
ent Air Quality Standards for particulate matter: Policy assessment of scientific
and technical information. OAQPS Staff Paper.
US. Environmental Protection Agency. 2004. Air quality criteria for
particulate matter.Volumes I (EPA/600/P-99/002aF) and II (EPA/600/
P-99/002bF). National Center for Environmental Assessment—RTF Office,
Office of Research and Development.
34 National Cancer Institute. 1999. Smoking and tobacco control monograph
10: Health effects of exposure to environmental tobacco smoke.
35 US. Department of Health and Human Services. 2006.The health conse-
quences ofinvoluntary exposure to tobacco smoke:A report of the Surgeon
General. Atlanta, GA. Centers for Disease Control and Prevention, Coordi-
nating Center for Health Promotion, National Center for Chronic Disease
Prevention and Health Promotion, Office on Smoking and Health.
36 U.S. Environmental Protection Agency. 2005. Review of the National Ambi-
ent Air Quality Standards for particulate matter: Policy assessment of scientific
and technical information. OAQPS Staff Paper.
37 U.S. Environmental Protection Agency. 2007. Review of the National
Ambient Air Quality Standards for ozone: Policy assessment of scientific and
technical information. OAQPS Staff Paper.
38 State of California. 2005. Proposed identification of environmental tobacco
smoke as a toxic air contaminant. Part B: Health effects assessment for
environmental tobacco smoke. As approved by the Scientific Review Panel
on June 24, 2005. California Environmental Protection Agency, Office of
Environmental Health Hazard Assessment,
5-40
EPA's 2008 Report on the Environment
-------
COPD is a group of diseases characterized by airflow obstruc-
tion, resulting in breathing-related symptoms and encompasses
chronic obstructive bronchitis and emphysema.39'40 COPD is
the fourth leading cause of death in the U.S. and is the leading
cause of hospitalization in U.S. adults, particularly in older
adults. It represents a major cause of morbidity, mortality, and
disability.41 Air pollution may be an important contributor
to COPD, though approximately 80 to 90 percent of COPD
deaths is generally attributed to smoking.42
Asthma continues to receive attention in both children and
adults. Asthma prevalence increased nearly 74 percent during
1980-1996.43 During 2001-2003, an average annual 20 mil-
lion people in the U.S. had asthma.44 Environmental con-
taminants such as dust mites, pets, mold, and other allergens
are considered important triggers for asthma.45 In addition,
the relationship between environmental tobacco smoke and
diseases of the respiratory tract has been studied extensively
in humans and in animals; environmental tobacco smoke has
been shown to produce a variety of upper and lower respiratory
tract disorders.46
Infectious Disease
Infectious diseases are acute illnesses caused by bacteria,
protozoa, fungi, and viruses. Food and water contaminated
\vith pathogenic microorganisms are the major environmental
sources of gastrointestinal illness. Though -well-established
systems for reporting food- and waterborne cases exist, data
reported through these largely voluntary programs must be
interpreted with caution because many factors can influence
•whether an infectious disease is recognized, investigated, and
reported. Changes in the number of cases reported could
reflect actual changes or simply changes in surveillance and
reporting. In addition, many milder cases of gastrointestinal
illnesses go unreported or are not diagnosed, making it dif-
ficult to estimate the number of people affected every year.
The discovery of bacterial contamination of drinking water
as the cause of many cases of gastrointestinal illness repre-
sents one of the great public health success stories of the 20th
century. Waterborne diseases such as typhoid fever and cholera
•were major health threats across the U.S. at the beginning of
the 20th century. Deaths due to diarrhea-like illnesses, includ-
ing typhoid, cholera, and dysentery, represented the third
largest cause of death in the nation at that time. These types of
diarrheal deaths dropped dramatically once scientists identified
the bacteria responsible, elucidated how these bacteria were
transmitted to and among humans in contaminated water
supplies, and developed effective water treatment methods to
remove pathogens from water supplies.
In addition to being of food- or waterborne origin, infec-
tious disease can be airborne, arthropod-borne (spread by
mosquitoes, ticks, fleas, etc.), or zoonotic (spread by rodents,
dogs, cats, and other animals). Legionellosis can be contracted
from naturally occurring bacteria found in water and spread
through poorly maintained artificial water systems (e.g., air
conditioning, ventilation systems). Arthropod-borne diseases,
including Lyme disease, Rocky Mountain spotted fever, and
West Nile virus, can be contracted from certain ticks and
mosquitoes that acquire bacteria or viruses by biting infected
mammals or birds.
Birth Outcomes
Birth defects are structural or functional anomalies that pres-
ent at birth or in early childhood. Birth defects cause physical
or mental disability and can be fatal. They affect approxi-
mately one out of 33 babies born each year in the U.S. and
remain the leading cause of infant mortality (Infant Mortal-
ity indicator, p. 5-36). Serious, adverse effects on health,
development, and functional ability may be experienced by
individuals born with birth defects.47 Birth defects have been
linked with a variety of possible risk factors that can affect
normal growth and development—genetic or chromosomal
aberrations, as well as environmental factors such as exposure
to chemicals; exposure to viruses and bacteria; and use of
cigarettes, drugs, or alcohol by the mother. The causes of most
birth defects are unknown, but research continues to show the
possible influence of environmental exposures (e.g., prenatal
exposure to high levels of contaminants such as mercury or
PCBs). The relationship between exposure to lower concen-
trations of environmental contaminants and birth defects,
however, is less clear.
Low birthweight delivery and preterm birth are considered
important risk factors for infant mortality and birth defects.
Low birthweight infants have a significantly increased risk of
infant death, and those who survive are more likely to experi-
ence long-term developmental disabilities.48 Multiple birth
babies have a low birthweight rate of more than 50 percent,
39 Mannino, D.M. 2002. COPD epidemiology, prevalence, morbidity and mor-
tality, and disease heterogeneity. Chest 121:1215-1265.
40 Barnes, P.J. 2000. Chronic obstructive pulmonary disease. Review article. N.
Engl. J. Med. 343 (4) :269-280.
41 Mannino, D.M., D.M. Homa, L.J. Akinbami, E.S. Ford, and S.C. Redd.
2002. Chronic obstructive pulmonary disease surveillance—United States,
1971-2000. In: Surveillance Summaries. MMWR 51(SS06):1-16.
42 American Lung Association. 2004. Chronic obstructive pulmonary disease
(COPD) fact sheet. Accessed February 7, 2005.
43 Mannino, D.M., D.M. Homa, L.J. Akinbami, J.E. Moorman, C. Gwynn, S.C.
Redd. 2002. Surveillance for asthma—United States, 1980-1999. In: Surveil-
lance Summaries. MMWR 51 (SS-1): 1-13.
44 Moorman,J.G., R.A. Rudd, C.A.Johnson, M. King, P. Minor, C. Bailey, M.R.
Scalia, L.J. Akinbami. 2007. National surveillance for asthma—United States,
1980-2004. In: Surveillance Summaries. MMWR 56(SS08):1-14.
45 U.S. Institute of Medicine. 2000. Clearing the air. Asthma and indoor air
exposures.Washington, DC: National Academy Press.
46 State of California. 2005. Proposed identification of environmental tobacco
smoke as a toxic air contaminant. Part B: health effects assessment for
environmental tobacco smoke. As approved by the Scientific Review Panel
on June 24, 2005. California Environmental Protection Agency, Office of
Environmental Health Hazard Assessment,
47 Centers for Disease Control and Prevention. 2006. Improved national
prevalence estimates for 18 selected major birth defects—United States,
1999-2001. MMWR 54(51&52):1301-1305.
48 National Center for Health Statistics. 2005. Health, United States, 2005,
with chartbook on trends in the health of Americans. DHHS publication no.
2005-1232. Hyattsville, MD p. 11.
EPA's 2008 Report on the Environment
5-41
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compared to approximately 6 percent among singletons,
among whom the low birthweight rate rose only 1 percent
from 1989 to 1998.49 To eliminate the effect that multiple
births may have on birth outcomes, this report presents data
for singleton births only.
Environmental exposures are being investigated for possible
associations with birth outcomes such as low birthweight,
preterm births, and infant mortality. Some of the risk factors
for low birthweight infants born at term include maternal
smoking, weight at conception, and nutrition and weight gain
during pregnancy.50 Specific examples of known or suspected
environmental contaminant influences on birth outcomes
include environmental tobacco smoke, lead, and air pollution.
The most robust evidence exists for environmental tobacco
smoke and lead.51 Environmental tobacco smoke is associated
•with increased risk of low birthweight, preterm delivery, and
sudden infant death syndrome.52 Several studies have identified
lead exposure as a risk factor for preterm delivery.53 Associa-
tions between air pollution and fetal growth and infant mor-
tality have been documented. Recent studies report significant
associations between PM1Q concentration averaged over a
month or a trimester of gestation and the risk of intrauterine
growth reduction and low birthweight.54 Growing evidence
shows exposure-response relationships between maternal
exposures to air pollutants (e.g., sulfur dioxide and particu-
lates) and preterm birth.55'56 Research continues, however, in
establishing causal relationships between air pollution and low
birthweight and preterm birth. Researchers also continue to
examine possible associations between other contaminants as
birth outcome risk factors, such as pesticides, polycyclic aro-
matic hydrocarbons, and others.
5.4.2 ROE Indicators
EPA has selected indicators of health outcomes for which
environmental exposures may be a risk factor and for which
nationally representative data are available. Nine indicators were
selected to address the question (Table 5-4)—two for cancer
(including the leading sites of cancer in adults and children),
one for cardiovascular disease (including coronary heart disease,
stroke, and hypertension), two related to respiratory disease
(including asthma and chronic lung conditions such as bronchi-
tis and emphysema), one for infectious diseases (composed of
multiple diseases and conditions), and three for birth outcomes.
Table 5-4. ROE Indicators of Trends in Human Disease and Conditions for Which
Environmental Contaminants May Be a Risk Factor
National Indicators
Cancer Incidence
Childhood Cancer Incidence
Cardiovascular Disease Prevalence and Mortality (N/R)
Chronic Obstructive Pulmonary Disease Prevalence and Mortality (N/R)
Asthma Prevalence
Infectious Diseases Associated with Environmental Exposures or Conditions
Birth Defects Prevalence and Mortality
Low Birthweight
Preterm Delivery
Section
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5.4.2
5-43
5-46
5-48
5-52
5-55
5-59
5-62
5-65
5-67
N/R = National Indicator displayed at EPA Regional scale
National Center for Health Statistics. 2001. Healthy people 2000 final review.
Hyattsville, MD: Public Health Service, p. 208.
U.S. Department of Health and Human Services. 2000. Healthy people 2010:
Understanding and improving health. Second edition. Washington, DC: US.
Government Printing Office,
Behrman, R.E., and A. Stith Butler, eds. 2007. Preterm birth: Causes, conse-
quences, and prevention. Committee on Understanding Premature Birth and
Assuring Healthy Outcomes. Institute of Medicine of the National Acad-
emies. Washington, DC: National Academies Press.
State of California. 2005. Proposed identification of environmental tobacco smoke
as a toxic air contaminant. Part B: Health effects assessment for environmental
tobacco smoke. As approved by the Scientific Review Panel on June 24,2005.
California Environmental Protection Agency, Office of Environmental Health
Hazard Assessment,
53 Agency for Toxic Substances and Disease Registry. 2005. lexicological profile
for lead (update). Draft for public comment. Atlanta, GA: U.S. Department of
Health and Human Services, Public Health Service.
54 US. Environmental Protection Agency 2005. Review of the National Ambi-
ent Air Quality Standards for particulate matter: Policy assessment of scientific
and technical information. OAQPS Staff Paper.
55 Behrman, R.E., and A. Stith Butler, eds. 2007. Preterm birth: Causes, conse-
quences, and prevention. Committee on Understanding Premature Birth and
Assuring Healthy Outcomes. Institute of Medicine of the National Acad-
emies. Washington, DC: National Academies Press.
56 Sram, R.J., B. BinkovaJ. Dejmek, and M. Bobak. 2005. Ambient air pollution
and pregnancy outcomes: A review of the literature. Environ. Health Perspect.
113(4):375-382.
5-42
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The indicators used to answer this question are drawn from the
Centers for Disease Control and Prevention's vital statistics and
surveillance data, including the CDC WONDER Mortality
Database, the Summary of Notifiable Diseases, the National
Center for Health Statistics' National Vital Statistics Reports
and VitalStats Database, and the National Health Interview
Survey, as well as the National Cancer Institute's Surveillance,
Epidemiology, and End Results Database. The time frames
covered generally range back to the 1970s for mortality and
incidence data and to the mid-1990s for prevalence data.
In answering this question, both disease morbidity (incidence
or prevalence) and mortality (resulting death) statistics are
used. Depending on the health outcome of interest, both mea-
sures can provide useful insights about trends in disease. Both
morbidity and mortality statistics are influenced by a number
of factors, however, such as the accuracy of reporting mecha-
nisms and issues related to access to, quality of, and advances
in medical care. An overall understanding of the disease
measures and associated statistics used to answer this question
is important (see Box 5-3).
Where possible, the indicators provide breakouts of population
subgroups, such as race, ethnicity, age, and gender. Subpopula-
tion data are presented to the extent practicable under "What
the Data Show," within text or shown in indicator figures.
For cardiovascular and respiratory diseases, mortality statistics
are provided for each of the 10 EPA Regions. For cancer, data
for the most frequently diagnosed cancer sites in adults and
children, along with overall cancer rates, are used to answer
the question.
Both morbidity and mortality can be measured using
occurrences or rates. Occurrences represent frequency
counts, while rates enable a comparison across populations.
Rates are ratios that calculate the frequency of cases (of dis-
ease, condition, outcome) divided by the size of the defined
population for a specified time period. Usually some con-
stant (generally a multiplier of the power 10) is applied to
convert the rate to a whole number.
Morbidity data are often used to describe the incidence and
prevalence of a disease or condition. Both incidence and
prevalence are often expressed as a rate per 1,000 persons
over a particular time period. "Incidence" refers to the
number of new cases of a disease or condition in a popula-
tion during a specified time period. "Prevalence" refers to
the total number of people with a given disease or condition
in a population at a specified point in time.
Mortality is generally expressed as a rate and is defined as
the proportion of the population who die of a disease or
condition during a specified time period. The rate is usu-
ally calculated for a calendar year and is often expressed per
100,000 persons.
Incidence, prevalence, and mortality statistics can be used
to compare the rates of disease at two or more points in
time, across different populations (ages, gender, racial/
ethnic groups), or between different geographic areas.
In general, disease incidence, prevalence, and mortality
increase with age. For this reason, when comparing dif-
ferent populations, the data must be adjusted to account
for the age differences between the populations. The
adjusted data, called "age-adjusted rates," are used where
possible in answering this question. Age-adjusted rates are
•weighted sums of age-specific rates and calculated using
standard population factors. (In this report, the 2000
U.S. standard population was used.) Unadjusted rates are
referred to as "crude" rates.
INDICATOI
Cancer Incidence
The term "cancer" is used to characterize diseases in
•which abnormal cells divide without control. A cancer-
ous cell loses its ability to regulate its own growth, control
cell division, and communicate with other cells. Cancer
cells can invade nearby tissues and can spread through the
bloodstream and lymphatic system to other parts of the
body (NCI, n.d.). The risk of developing cancer increases
•with age. Environmental exposures, genetic predisposition,
certain viruses, and socioeconomic factors may all play a
role in the development and progression of the disease.
For the U.S. population, age-adjusted cancer incidence
rates for all sites combined have been stable since 1992
(Edwards et al., 2005). Nevertheless, cancer continues to be
the second leading cause of death in the U.S., accounting for
about 23 percent of all deaths in 2004 (General Mortality
indicator, p. 5-33) (NCHS, 2007). Many different types of
cancer exist. These can develop in various organs and tissues
•within the body and contributing causal factors can vary
depending on the cancer site and type. Therefore, tracking
rates for individual cancer sites is more meaningful when
evaluating cancer trends.
Many factors are known to contribute, or suspected of
contributing, to cancer risk. Factors including individual
food and beverage preferences, use of tobacco products,
exposure to natural and medical radiation (including sun-
light), -workplace exposures, and pharmaceutical use as well
as exposure to substances in the air, water and soil all may
contribute individually (i.e., additively) or synergistically
EPA's 2008 Report on the Environment
5-43
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INDICATOI
Cancer Incidence (continued)
Exhibit 5-17. Age-adjusted cancer incidence
rates in the U.S., 1973-2004: All cancer sites for
all ages, by race and sex"
- 600
8
40°
CD O.
<"
200
75
'85 '90 '95 '00
Year of diagnosis
"Rates are age-adjusted to the 2000 U.S.
standard population.
Data source: NCI, 2007
(i.e., producing an effect greater than the sum of each factor
acting alone) to the development of cancer (NTP, 2004).
Further, the cancer hazard to any individual is dependent
on the amount and duration of exposure and the indi-
vidual's susceptibility to a particular substance. Only in a
small number of cases is it known what specific exposures or
conditions are responsible for the onset and development of
cancers (NTP, 2004).
This indicator presents cancer incidence rates for the
U.S. population using data collected through the National
Cancer Institute's Surveillance, Epidemiology, and End
Results (SEER) Program. The SEER Program collects
and publishes cancer incidence and survival data from 14
population-based cancer registries and three supplemental
registries covering approximately 26 percent of the U.S.
population. The 10 most commonly diagnosed cancer sites
presented are based on 2004 data compiled from SEER.
Site classifications (e.g., lung and bronchus, colon and
rectum) were compared to the American Cancer Society's
"leading sites" classification to ensure consistency in how
data are presented (ACS, 2004).
What the Data Show
Although a slow steady increase in cancer incidence
occurred between 1973 and 1992, peaking in 1992 with
an age-adjusted cancer incidence of 510 cases per 100,000,
Exhibit 5-18. Age-adjusted cancer incidence rates in the U.S., 2004: Ten leading cancer sites by sexa
Percent of all cancers Rateb Male
29.9 • 159.5 Prostate
13.8( 73.6 Lung and bronchus
10.6| 56.7 Colon and rectum
6.8 B 36.3 Urinary bladder
4.6| 24.7 Non-Hodgkin's lymphoma
4.5| 24.1 Melanoma of the skin
3.3| 17.8 Kidney and renal pelvis
2.9J 15.5 Oral cavity and pharynx
2.9J 15.4 Leukemia
2.5 1 13.3 Pancreas
18.2 NC° Allothersites
Excludes basal and squamous cell skin cancers and in situ carcinoma,
Female
Breast
Lung and bronchus
Colon and rectum
Corpus uteri
Non-Hodgkin's lymphoma
Melanoma of the skin
Thyroid
Ovary
Pancreas
Urinary bladder
All other sites
except urinary bladder.
Rateb Percent of all cancers
124.3 ^^^^^^H30.7
50.2 |12.4
41.7 ^H 10.3
23.9 H5.9
17.1 H4-2
16.5 H4.1
14.4 3.6
12.6 3.1
9.8 2.4
9.1 2.2
NC° ^^"21-1
bRates are per 100,000 and age-adjusted to the 2000 U.S. standard population.
CNC = not calculated
Data source: NCI, 2007
5-44
EPA's 2008 Report on the Environment
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INDICATOI
Cancer Incidence (continued)
Exhibit
rates in
males c
250
200
QJ
"g 1 15°
to o"
•— ?
~O j_ ^ gg
I 0
CD O.
O) -— '
50
0
aRates are
2000 U.S
Data sou
5-19. Age-adjusted cancer incidence
the U.S., 1973-2004: Top five cancers in
fall ages3
A
^^^^^
75 '80 '85 '90 '95 '00
Year of diagnosis
age-adjusted to the Colon and rectum
standard population. Lung and bronchus
rce: NCI, 2007 — Non-Hodgkin's lymphoma
Prostate
— Urinary bladder
Exhibit
rates in
females
140
120
.22
•5 o 80
13 o
"? "5 60
-------
INDICATOR
Cancer Incidence (continued)
Recent trends in cancer incidence rates among the less
prevalent site-specific cancers in females showed increases
for melanoma, which ranged from 13.7 (1995) to 16.5 (2004)
cases per 100,000 and thyroid cancer, which ranged from
8.9 (1995) to 14.4 (2004) cases per 100,000. Incidence rates
decreased for cancers of the ovary, which ranged from 14.7
(1997) to 12.6 (2004) cases per 100,000. (Data not shown.)
Indicator Limitations
• SEER data cover approximately 26 percent of the U.S.
population, though it is designed to be representative of
the entire U.S. population.
• Incidence data generated from SEER are updated
annually. There may be changes in the numerator (e.g.,
revised counts of newly identified cases) or denomina-
tor (i.e., revised population counts) numbers that result
in small changes in the overall incidence rates for the
same year, depending on when a query is run within the
SEER database. For example, the SEER database queried
in 2005 generating incidence rates for the year 2000 may
provide different incidence rates than the database que-
ried in 2004 for the year 2000.
Data Sources
Cancer incidence data for this indicator were obtained by
querying the National Cancer Institute's SEER Program
database through the Cancer Query Systems Web-based
interface (NCI, 2007), available at http://www.seer.cancer.
gov/canques/incidence.html.
References
ACS (American Cancer Society). 2004. Cancer facts and
figures, 2004.
Hankey, B.F., EJ. Feuer, L.X. Clegg, R.B. Hayes, J.M.
Legler, P.C. Prorok, et al. 1999. Cancer surveillance series:
Interpreting trends in prostate cancer-part I: Evidence of
the effects of screening in recent prostate cancer incidence,
mortality, and survival rates. J. Natl. Cancer Inst.
91(12):1017-1024.
Edwards, K.E., M.L. Brown, P.A. Wmgo, H.L. Howe, E.
Ward, L. Reis, et al. 2005. Annual report to the nation on
the status of cancer, 1975-2002, featuring population-based
trends in cancer treatment. J. Natl. Cancer Inst.
97(19):1407-1427.
NCHS (National Center for Health Statistics). 2007.
Deaths: Final data for 2004. National Vital Statistics
Reports 55(19).
NCI (National Cancer Institute). 2007. Surveillance, Epi-
demiology, and End Results (SEER) Program CANQUES
database. SEER registry limited use, Nov 2006, Sub
(1973-2004). National Cancer Institute, DCCPS, Surveil-
lance Research Program. Released April 2007, based on
November 2006 submission. Accessed September 2007.
NCI. n.d. Dictionary of cancer terms. Accessed October 7,
2004.
NTP (National Toxicology Program). 2004. Report on
carcinogens. Eleventh edition. U.S. Department of Health
and Human Services, Public Health Service.
INDICATOR
Childhood Cancer Incidence
The term "cancer" is used to characterize diseases in
•which abnormal cells divide without control. A cancer-
ous cell loses its ability to regulate its own growth, control
cell division, and communicate with other cells. If left
unchecked, cancer cells can invade nearby tissues and can
spread through the bloodstream and lymphatic system to
other parts of the body. The cellular changes caused by can-
cer cells are complex and occur over a period of time. This
may be accelerated in children. The classification of cancers
in children differs from the classification used for adult can-
cers. The International Classification of Childhood Cancer
classifies childhood cancer based on tumor morphology
rather than, as for adults, the site of the tumor (NCI, 2004).
The causes of childhood cancers are largely unknown.
Only a small percentage of cases can be explained by a few
conditions such as specific chromosomal/genetic abnor-
malities (e.g., Down's syndrome) and ionizing radiation
exposure (NCI, 2005). Environmental exposures have long
been suspected of increasing the risk of certain childhood
cancers. Researchers continue to examine environmental
influences on childhood cancer (NCI, 2005).
This indicator presents incidence rates for childhood can-
cers using data collected through the National Cancer Insti-
tute's Surveillance, Epidemiology, and End Results (SEER)
Program. The SEER Program collects and publishes cancer
incidence and survival data from 14 population-based cancer
5-46
EPA's 2008 Report on the Environment
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INDICATOI
Childhood Cancer Incidence (continued)
Exhibit 5-21. Age-adjusted cancer incidence
rates in the U.S., 1973-2004: All cancer sites for
ages 0-19, by race and sexa
20
16
12
8
75
'85 '90 '95 '00
Year of diagnosis
"Rates are age-adjusted to the 2000 U.S.
standard population, age 0-19 years.
Data source: NCI, 2007
registries and three supplemental registries covering approxi-
mately 26 percent of the U.S. population.
What the Data Show
In general, overall childhood (ages 0-19 years) cancer
incidence for the U.S. has increased slightly between 1973
and 2004 (Exhibit 5-21), increasing over time from an
age-adjusted incidence rate of 13.8 per 100,000 in 1973
to a high of 17.2 per 100,000 in 2002. A rate of 16.0 per
100,000) was reported in 2004. Males generally had higher
rates than females, although for some years the reverse was
true. Incidence among black females and males age 0-19
years was lower than among white females and males. In
2004, black females and males age 0-19 years had overall
incidence rates of 13.5 and 12.3 per 100,000, respectively,
compared to white females and males with rates of 15.5
and 18.7 per 100,000 (Exhibit 5-21).
Exhibit 5-22 presents the age-adjusted incidence rates
for the top five cancers among children 0-19 years of age
between 1973 and 2004. In general, there are no clearly
identifiable trends among any of the top five cancers over the
reported time period. Leukemia continues to be the most
frequently diagnosed cancer in children age 0-19 years.
Indicator Limitations
• SEER data cover approximately 26 percent of the U.S.
population, though it is designed to be representative of
the entire U.S. population.
• Incidence data generated from SEER are updated
annually. There may be changes in the numerator (e.g.,
Exhibit 5-22. Age-adjusted cancer incidence
rates in the U.S., 1973-2004: Top five cancers
forages 0-19a
- 2
75 '80 '85 '90 '95
Year of diagnosis
aRates are age-adjusted to the
2000 U.S. standard population,
age 0-19 years.
Data source: NCI, 2007
Brain and other nervous
system
Hodgkin'slymphoma
— Leukemia
— Lymphoma
Non-Hodgkin's lymphoma
revised counts of newly identified cases) or denomina-
tor (i.e., revised population counts) numbers that result
in small changes in the overall incidence rates for the
same year, depending on when a query is run within the
SEER database. For example, the SEER database queried
in 2005 generating incidence rates for the year 2000 may
provide different incidence rates than the database que-
ried in 2004 for the year 2000.
Data Sources
Cancer incidence data for this indicator were obtained by
querying the National Cancer Institute's SEER Program
database through the Cancer Query Systems Web-based
interface (NCI, 2007), available at http://www.seer.cancer.
gov/canques/incidence.html.
References
NCI (National Cancer Institute). 2007. Surveillance, Epi-
demiology, and End Results (SEER) Program CANQUES
database. SEER registry limited use, Nov 2006, Sub
(1973-2004). National Cancer Institute, DCCPS, Surveil-
lance Research Program. Released April 2007, based on
November 2006 submission. Accessed September 2007.
NCI. 2005. National Cancer Institute research on child-
hood cancers. Accessed November 2007.
NCI. 2004. Dictionary of cancer terms. Accessed October
7, 2004.
EPA's 2008 Report on the Environment
5-47
-------
INDICATOI
Cardiovascular Disease Prevalence and Mortality
The broad category of cardiovascular disease (CVD)
includes any disease involving the heart and blood
vessels. Coronary heart disease, cerebrovascular disease
(commonly known as stroke), and hypertension are the
major cardiovascular diseases (American Heart Association,
2007). In addition to being a major risk factor for heart
disease and stroke, hypertension is a commonly diagnosed
disease that can also lead to kidney damage and other
health problems. Obesity, physical inactivity, and sodium
intake are all important risk factors for hypertension (NIH,
2004). Since 1900, CVD has been the leading cause of
death in the U.S. every year except 1918 (American Heart
Association, 2007) (General Mortality indicator, p. 5-33).
The U.S. age-adjusted mortality rate for CVD reached a
peak in 1950 (CDC, 1999). Between 1950 and 1999, the
age-adjusted mortality rate for CVD declined 60 percent.
The major risk factors for CVD include tobacco use, high
blood pressure, high blood cholesterol, diabetes, physi-
cal inactivity, and poor nutrition (CDC, 2004; American
Heart Association, 2007).
Environmental exposures may also play a role in CVD
morbidity and mortality independent of other risk factors.
However, susceptible populations such as the elderly and
other high-risk populations may be most impacted. For
example, studies have shown exposure to ambient air-
borne particulate matter to be associated with increased
hospitalizations and mortality among older individu-
als, largely due to cardiopulmonary and cardiovascular
disease (U.S. EPA, 2004). Environmental tobacco smoke
(ETS) may also contribute to CVD. Although the smoke
to which a nonsmoker is exposed is less concentrated
than that inhaled by smokers, research has demonstrated
increased cardiovascular-related health risks associated
with ETS (State of California, 2005).
This indicator presents U.S. adult (age 18 and older)
prevalence rates for heart disease (all types), coronary heart
disease, stroke, and hypertension; and mortality rates for
CVD as a whole as well as coronary heart disease (includ-
ing myocardial infarction), stroke, and hypertension. CVD
prevalence data were compiled between 1997 and 2006
from the National Health Interview Survey (NHIS), con-
ducted by the Centers for Disease Control and Prevention's
(CDC's) National Center for Health Statistics (NCHS).
The NHIS is the principal source of information on the
health of the civilian non-institutionalized population of
the U.S. and since 1960 has been one of the major data col-
lection programs of NCHS. CVD prevalence is based on
the number of adults who reported that they had ever been
told by a doctor or other health practitioner that they had
a specified CVD. Mortality data (all ages) were compiled
between 1979 and 2004 using the National Vital Statis-
tics System (NVSS), maintained by NCHS. The NVSS
Exhibit 5-23. Cardiovascular disease
prevalence in U.S. adults (age 18 and older),
1 997-20063
200
0
° 150
— 100
CD
cc
50
o
'9
_^__ — ^
7 '98 '99 '00 '01 '02 '03 '04 '05 '0
6
Year
°Rates presented are crude rates. _ Hear( djsease
Data source: NCHS, 1999-2005, 2006a,b, (all types)
2007 » Heart disease
(coronary)
•*• Hypertension
•*- Stroke
Exhibit 5-24. Age-adjusted cardiovascular
disease mortality rates in the U.S., 1979-2004at
600
500
.22
£ SMOO
1°
^ o 300
100
'85
'90
'95
'00
Year
aDue to differences in the ICD system used for
classifying mortality, data from 1979-1998
should not be directly compared to data from
1999-2004 [ICD-9 codes: 390-434,436-448
(1979-1998); ICD-10 codes: IOO-I78
(1999-2004)].
"Rates are age-adjusted to the 2000 U.S.
standard population.
Data source: CDC, 2007
registers virtually all deaths and births nation-wide, with
data coverage from 1933 to 2004 and from all 50 states and
the District of Columbia.
5-48
EPA's 2008 Report on the Environment
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INDICATOI
Cardiovascular Disease Prevalence and Mortality (continued)
What the Data Show
CVD Prevalence
Among adults 18 years and older, the prevalence of heart
disease and stroke between 1997 and 2006 has remained
essentially the same (Exhibit 5-23). In contrast, the preva-
lence of hypertension has shown an increase from 191.6
cases per 1,000 in 1999 to 234.1 cases per 1,000 in 2006.
Gender, race, and age differences in CVD prevalence
exist. The prevalence of coronary heart disease is consis-
tently higher among males than among females (74.1 cases
per 1,000 compared with 54.2 cases per 1,000 for women
in 2006). In contrast, hypertension is more prevalent
among women (238.4 cases per 1,000 for women compared
•with 229.5 for men in 2006). Among the racial groups
reported, American Indians and Alaska Natives typi-
cally had the highest prevalence of coronary heart disease
between 1999 and 2003. In 2006, however, whites had the
highest prevalence of coronary heart disease (67.8 cases per
1,000), followed by American Indians and Alaska Natives
(55.5 cases per 1,000), blacks or African Americans (52.0
cases per 1,000), and Asians (28.6 cases per 1,000). In 2006,
Asians also consistently had the lowest prevalence of stroke
(13.8 cases per 1,000) and hypertension (157.0 cases per
1,000) among the racial groups reported. In addition, the
Hispanic or Latino population had a consistently lower
prevalence of the major CVD-related diseases com-
pared with the non-Hispanic or Latino population from
1999-2006, the period for which these data are available.
For example, in 2006, prevalence in Hispanics or Latinos
\vas lower than in non-Hispanics or Latinos for coronary
heart disease (31.7 versus 68.6 cases per 1,000, respec-
tively), hypertension (147.5 versus 247.0 cases per 1,000,
respectively), and stroke (12.2 versus 27.6 cases per 1,000,
respectively). (Data not shown.)
CVD Mortality
In 1998, the national age-adjusted CVD mortality rate (all
types) \vas 352.0 per 100,000 compared to a rate of 541.0
per 100,000 in 1980 (Exhibit 5-24). This decline appears
to continue after 1999, with the rate dropping from 349.3
per 100,000 in 1999 to 286.5 per 100,000 in 2004. Both
coronary heart disease and stroke mortality rates have been
declining in the U.S. The age-adjusted coronary heart
disease mortality rate ranged from 345.2 per 100,000 in
1980 to 197.1 per 100,000 in 1998. For stroke mortality, the
age-adjusted rate ranged from 97.1 per 100,000 in 1979 to
59.3 per 100,000 in 1998. The age-adjusted mortality rates
for myocardial infarction ranged from 157.9 in 1979 to 76
per 100,000 in 1998. The age-adjusted mortality rates for
coronary heart disease, stroke, and myocardial infarction in
2004 were 150.2, 50.0, and 52.3 per 100,000, respectively,
compared to 194.6, 61.6, and 73.2 per 100,000, respectively,
Exhibit 5-25. Age-adjusted coronary heart
disease mortality rates in the U.S. by EPA
Region, 1979-2004ab
450
400
350
.3^300
"S § 250
38
150
100
50
0
R1
R2
R3
R4
-R5
R6
R7
R8
-R9
-R10
-Nat'l
'85
'90 '95
Year
'00
aDue to differences in the ICD
system used for classifying
mortality, data from 1979-1998
should not be directly compared
to data from 1999-2004 [ICD-9
codes: 410-414, 429.2
(1979-1998); ICD-10 codes:
I20-I25 (I999-2004)].
bRates are age-adjusted to the
2000 U.S. standard population.
Data source: CDC, 2007
EPA Regions
in 1999. Death rates from hypertension remained essentially
the same between 1999 and 2004.
Both coronary heart disease and stroke mortality have
been declining over time in each of the 10 EPA Regions
(Exhibits 5-25 and 5-26). In 1979, coronary heart disease
and stroke age-adjusted mortality rates ranged from 285.6
(Region 10) to 401.9 (Region 2) per 100,000 and 80.3
(Region 2) to 111.4 (Region 4) per 100,000, respectively.
In 1998, coronary heart disease and stroke mortality rates
ranged from 145.6 (Region 8) to 233.2 (Region 2) per
100,000 and 43.2 (Region 2) to 68.5 per (Region 10)
100,000, respectively. The observed decreases in coronary
heart disease and stroke mortality also appear to continue
in the 1999-2004 period.
Differences exist in CVD mortality rates among gender,
racial, and age groups. For example, in 2004, those age 65
and older had the highest CVD (all types), coronary heart
disease, and stroke mortality (1,898.7, 990.8, and 346.2 per
100,000, respectively). For the same year, the age-adjusted
CVD, coronary heart disease, and stroke mortality rates for
EPA's 2008 Report on the Environment
5-49
-------
INDICATOI
Cardiovascular Disease Prevalence and Mortality (continued)
those 45 to 64 years of age were 172.7, 98.5, and 22.5 per
100,000, respectively. Notable differences in CVD (all types)
and, specifically, coronary heart disease mortality rates
exist between males and females, but not for stroke mortal-
ity. Coronary heart disease mortality among males in 2004
was 194.2 per 100,000, compared to 116.7 per 100,000 for
•women. In 2004, black or African American males had the
highest CVD mortality rate at 451.1 per 100,000 compared
to white males (333.6 per 100,000), black or African Ameri-
can females (331.0 per 100,000), and white females (236.7
per 100,000). (Data not shown.)
Indicator Limitations
• Prevalence data reported in the NHIS are based on
self-reported responses to specific questions pertaining
to CVD-related illnesses, and are subject to the biases
associated with self-reported data. Self-reported data can
underestimate the disease prevalence being measured if,
for -whatever reason, the respondent is not fully aware of
his/her condition.
• All prevalence data are based on crude rates and are not
age-adjusted, as CDC did not report age-adjusted data
prior to 2002 in the data sources used for this indicator.
Therefore, the reported disease prevalence rates across
time or within different race and gender subgroups
may not reflect differences in the age distribution of the
populations being compared.
• For one or more years for which data are presented,
coronary heart disease and stroke prevalence rates pre-
sented for Native Americans and Alaska Natives have
a relative standard error of greater than 30 percent. In
addition, stroke prevalence rates for one or more years
for \vhich data are presented for Asians have a relative
standard error of greater than 30 percent. As such, these
rates should be used -with caution as they do not meet the
standard of reliability or precision.
• CVD mortality rates are based on underlying cause of
death as entered on a death certificate by a physician.
Some individuals may have had competing causes of
death. "When more than one cause or condition is entered
by the physician, the underlying cause is determined by
the sequence of conditions on the certificate, provisions
of the ICD [International Classification of Diseases], and
associated selection rules and modifications" (CDC, n.d.).
Consequently, some misclassification of reported mortal-
ity might occur in individuals -with competing causes of
death, as -well as the possible underreporting of CVD as
the cause of death.
• The International Classification of Diseases 9th Revision
(ICD-9) codes -were used to specify underlying cause
of death for years 1979-1998. Beginning in 1999, cause
of death is specified -with the International Classifica-
tion of Diseases 10th Revision (ICD-10) codes. The two
Exhibit 5-26. Age-adjusted stroke mortality
rates in the U.S. by EPA Region, 1979-2004ab
120
100
£ 80
60
CD Q.
3~
40
20
—R1
-R2
—R3
R4
-R5
-R6
R7
R8
—R9
-R10
-Nat'l
'85
'90 '95
Year
'00
aDue to differences in the ICD
system used for classifying
mortality, data from 1979-1998
should not be directly compared
to data from 1999-2004 [ICD-9
codes: 430-434, 436-438
(1979-1998); ICD-10 codes:
160-169(1999-2004)].
bRates are age-adjusted to the
2000 U.S. standard population.
Data source: CDC, 2007
revisions differ substantially, and to prevent confusion
about the significance of any specific disease code, data
queries are separate.
Data Sources
CVD prevalence data -were obtained from annual reports
published by NCHS (NCHS, 1999-2007), which summa-
rize health statistics compiled from the NHIS (http://www
cdc.gov/nchs/products/pubs/pubd/series/ser.htm). CVD
mortality statistics -were obtained from CDC's "compressed
mortality" database, accessed through CDC WONDER
(CDC, 2007) (http://wonder.cdc.gov/mortSQL.html). EPA
Regional mortality statistics -were generated by combining
and age-adjusting state-by-state totals for each EPA Region
using data from CDC WONDER.
References
American Heart Association. 2007. Heart disease and
stroke statistics—2007 update. A report from the American
Heart Association Statistics Committee and Stroke Statis-
tics Subcommittee. Circulation (115):e69-el71.
5-50
EPA's 2008 Report on the Environment
-------
Cardiovascular Disease Prevalence and Mortality (continued)
CDC (Centers for Disease Control and Prevention). 2007.
CDC Wide-ranging OnLine Data for Epidemiologic
Research (WONDER). Compressed mortality file, under-
lying cause of death. 1999-2004 (with ICD 10 codes) and
1979-1998 (with ICD 9 codes). Accessed September 2007.
CDC. 2004. The burden of chronic diseases and their risk
factors—national and state perspectives,
CDC. 1999. Decline in deaths from heart disease and
stroke, United States, 1990-1999. Washington, DC.
CDC. n.d. CDC WONDER: Help page for compressed
mortality file. Accessed September 2007.
NCHS (National Center for Health Statistics). 2007.
Summary health statistics for U.S. adults: National Health
Interview Survey, 2006. Vital Health Stat. 10(235).
NCHS. 2006a. Summary health statistics for U.S. adults:
National Health Interview Survey, 2005. Vital Health Stat.
10(232).
NCHS. 2006b. Summary health statistics for U.S. adults:
National Health Interview Survey, 2004. Vital Health Stat.
10(228).
NCHS. 2005. Summary health statistics for U.S. adults:
National Health Interview Survey, 2003. Vital Health Stat.
10(225).
NCHS. 2004. Summary health statistics for U.S. adults:
National Health Interview Survey, 2002. Vital Health Stat.
10(222).
NCHS. 2003. Summary health statistics for U.S. adults:
National Health Interview Survey, 2001. Vital Health Stat.
10(218).
NCHS. 2002. Summary health statistics for U.S. adults:
National Health Interview Survey, 2000. Vital Health Stat.
10(215).
NCHS. 2001. Summary health statistics for U.S. adults:
National Health Interview Survey, 1999. Vital Health Stat.
10(212).
NCHS. 2000. Summary health statistics for U.S. adults:
National Health Interview Survey, 1998. Vital Health Stat.
10(209).
NCHS. 1999. Summary health statistics for U.S. adults:
National Health Interview Survey, 1997. Vital Health Stat.
10(205).
NIH (National Institute of Health). 2004. NIH news: The
increasing number of adults with high blood pressure.
State of California. 2005. Proposed identification of envi-
ronmental tobacco smoke as a toxic air contaminant. Part B:
Health effects assessment for environmental tobacco smoke.
As approved by the Scientific Review Panel on June 24,
2005. California Environmental Protection Agency, Office
of Environmental Health Hazard Assessment.
U.S. EPA (United States Environmental Protection Agency).
2004. Air quality criteria for particulate matter. Volumes
I (EPA/600/P-99/002aF) and II (EPA/60O/P-99/002bF).
National Center for Environmental Assessment—RTF
Office, Office of Research and Development.
EPA's 2008 Report on the Environment
5-51
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INDICATOR
Chronic Obstructive Pulmonary Disease Prevalence
and Mortality
Chronic obstructive pulmonary disease (COPD), some-
times referred to as chronic lung disease, is a disease
that damages lung tissue or restricts airflow through the
bronchioles and bronchi (NHLBI, 2003). Chronic bron-
chitis and emphysema are the most frequently occurring
COPDs. Smoking is the most common cause of COPD,
including cigarette, pipe, and cigar smoking (NHLBI,
2003). Other risk factors in the development and progres-
sion of COPD include asthma, exposure to air pollutants
in the ambient air and -workplace environment, genetic
factors, and respiratory infections (CDC, 2003; American
Lung Association, 2004).
Environmental tobacco smoke (ETS) may also increase
the risk of developing COPD. The effect of chronic ETS
exposure alone on pulmonary function in otherwise healthy
adults is likely to be small. However, in combination with
other exposures (e.g., prior smoking history, exposure to
occupational irritants or ambient air pollutants), ETS expo-
sure could contribute to chronic respiratory impairment.
Children are especially sensitive to the respiratory effects of
ETS exposure (State of California, 2005).
This indicator presents U.S. adult (age 18 and older)
prevalence rates for chronic bronchitis and emphysema
and mortality rates for COPD as a whole and for chronic
bronchitis and emphysema. COPD prevalence data were
compiled from 1999 to 2006 from the National Health
Interview Survey (NHIS), conducted by the Centers for
Disease Control and Prevention's (CDC's) National Center
for Health Statistics (NCHS). The NHIS is the principal
source of information on the health of the civilian non-
institutionalized population of the U.S. and since 1960 has
been one of the major data collection programs of NCHS.
COPD prevalence is based on the number of adults who
reported that they had ever been told by a doctor or
other health practitioner that they had chronic bronchitis
or emphysema. Mortality data (all ages) were compiled
between 1979 and 2004 using the National Vital Statistics
System (NVSS), maintained by NCHS. The NVSS reg-
isters virtually all deaths and births nation-wide, -with data
coverage from 1933 to 2004 and from all 50 states and the
District of Columbia.
What the Data Show
COPD Prevalence
Exhibit 5-27 presents the prevalence of chronic bronchitis
(panel A) and emphysema (panel B) from 1999 to 2006.
The reported total prevalence of chronic bronchitis in
U.S. adults over the age of 18 years ranged from a low of
40 (2003) to a high of 55 (2001) cases per 1,000. A small
increase in prevalence of chronic bronchitis can be seen
from 1999 to 2001, -with a subsequent overall decline from
2001 to 2006. The reported total prevalence of emphy-
sema in U.S. adults during the same time period ranged
from 14 (1999) to 18 (2006) cases per 1,000. No notable
change in the prevalence for emphysema -was evident dur-
ing this time period. Exhibit 5-27 also displays chronic
bronchitis and emphysema prevalence by race. Chronic
bronchitis prevalence -was higher among -white (designated
as "-white only") adults than black ("black or African
American only") adults during 1999 (46 versus 36 cases per
1,000, respectively), 2000 (49 versus 40 cases per 1,000,
respectively), and 2004 (44 versus 36 cases per 1,000,
respectively). However, in 2006 rates in black and -white
adults are the same (43 cases per 1,000). Throughout the
entire time period, emphysema prevalence is consistently
higher among -white adults than black adults.
In addition, the Hispanic or Latino population had a
consistently lower prevalence of chronic bronchitis and
Exhibit 5-27. Chronic bronchitis and emphysema prevalence in U.S. adults (age 18 and older) by
race, 1999-2006a
A. Chronic bronchitis
60
50
| 40
r 30
CD
Q.
B 20
ro
CC
10
0
B. Emphysema
aRates presented are
crude rates.
Data source: NCHS,
2001-2005, 2006a,b,
2007
'99 '00
'01
'02 '03
'04
'05 '06 '99 '00
'01
'02
'03 '04 '05 '06
Year
5-52
EPA's 2008 Report on the Environment
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INDICATOI
Chronic Obstructive Pulmonary Disease Prevalence
and Mortality (continued)
emphysema diseases than the non-Hispanic or Latino pop-
ulation from 1999-2006, the period for which these data
are available. For example, in 2006, prevalence in Hispan-
ics or Latinos was lower than non-Hispanics or Latinos
for chronic bronchitis (22 compared to 46 cases per 1,000,
respectively) and emphysema (4 compared to 21 cases per
1,000, respectively). (Data not shown.)
Gender differences are also seen. In 2006, females had
about twice the reported prevalence of chronic bronchitis
than males (57 versus 27 cases per 1,000 respectively), a
consistently observed difference between 1997 and 2006.
Unlike with chronic bronchitis, the prevalence rates for
emphysema have been consistently higher in males than in
females. (Data not shown.)
COPD Mortality
In 2004, COPD continues to be the fourth leading cause
of mortality, accounting for 121,987 (5.1 percent) of all
deaths (General Mortality indicator, p. 5-33). The age-
adjusted mortality rate for COPD as a whole has increased
over time, with rates ranging from 25.5 per 100,000 in
1979 to 41.8 per 100,000 in 1998. From 1999 to 2004,
rates held steadier, ranging from 45.4 per 100,000 in
1999 to 41.1 per 100,000 in 2004. Mortality rates for
emphysema (6.9 and 6.5 per 100,000 for 1979 and 1998,
respectively, and 6.5 and 4.6 per 100,000 for 1999 and
2004, respectively) and chronic bronchitis (1.7 and 0.9
per 100,000 for 1979 and 1998, respectively, and 0.2 and
0.1 per 100,000 for 1999 and 2004, respectively) have not
changed substantially during the same time period. (Data
not shown.)
Exhibit 5-28 presents the overall COPD mortality
rates in the U.S. and the 10 EPA Regions for 1979-1998
and 1999-2004. The age-adjusted COPD mortality rates
have been increasing in each of the 10 Regions from
1979 to 1998. The rates ranged from 22.2 (Region 2) to
31.2 (Region 8) per 100,000 in 1979 and 33.5 (Region
2) to 47.9 (Region 8) per 100,000 in 1998. Between 1999
and 2004, COPD mortality rates in each of the 10 EPA
Regions have generally declined.
COPD age-adjusted mortality rates have been declin-
ing for males over time, with a rate of 58.7 per 100,000 in
1999 compared to 49.5 per 100,000 in 2004. For females,
the rates are lower than males and have been relatively
stable between 1999 and 2004 (37.7 and 36.0 per 100,000,
respectively). The COPD age-adjusted mortality rate is
higher among whites (43.2 per 100,000 in 2004) com-
pared to blacks or African Americans (28.2 per 100,000 in
2004). COPD mortality rate increases with age: the 2004
rates were 0.3, 1.1, 21.0, and 284.3 per 100,000 for those
age 0-14 years, 15-44 years, 45-64 years, and 65 years and
older, respectively. (Data not shown.)
Exhibit 5-28. Age-adjusted chronic obstructive
pulmonary disease mortality rates in the U.S. by
EPA Region, 1979-2004ab
'90
'95
'00
Year
aDue to differences in the ICD
system used for classifying
mortality, data from 1979-1998
should not be directly compared
to data from 1999-2004 [ICD-9
codes: 490-494, 496
(1979-1998); ICD-10 codes:
J40-J47 (1999-2004)].
bRates are age-adjusted to the
2000 U.S. standard population.
Data source: CDC, 2007
EPA Regions
Indicator Limitations
• Prevalence data presented in the NHIS are based on
self-reported responses to specific questions pertaining
to COPD-related illnesses, and are subject to the biases
associated with self-reported data. Self-reported data can
underestimate the disease prevalence being measured if,
for -whatever reason, the respondent is not fully aware of
his/her condition.
• All prevalence data are based on crude rates and are not
age-adjusted, as CDC did not report age-adjusted data
prior to 2002 in the data sources used for this indicator.
Therefore, the reported disease prevalence rates across
time or within different race and gender subgroups
may not reflect differences in the age distribution of the
populations being compared.
• COPD mortality rates are based on underlying cause
of death as entered on a death certificate by a physi-
cian. Some individuals may have had competing causes
of death. "When more than one cause or condition is
EPA's 2008 Report on the Environment
5-53
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INDICATOR
Chronic Obstructive Pulmonary Disease Prevalence
and Mortality (continued)
entered by the physician, the underlying cause is deter-
mined by the sequence of conditions on the certificate,
provisions of the ICD [International Classification of
Diseases], and associated selection rules and modifica-
tions" (CDC, n.d.). Consequently, some misclassifica-
tion of reported mortality might occur in individuals
•with competing causes of death, as well as the possible
underreporting of COPD as the cause of death.
• The International Classification of Diseases 9th Revision
(ICD-9) codes were used to specify underlying cause of
death for years 1979-1998. Beginning in 1999, cause of
death is specified with the International Classification of
Diseases 10th Revision (ICD-10) codes. The two revi-
sions differ substantially, and to prevent confusion about
the significance of any specific disease code, data queries
are separate.
Data Sources
COPD prevalence data were obtained from annual reports
published by NCHS (NCHS, 2001-2005, 2006a,b, 2007),
•which summarize health statistics compiled from the NHIS
(http://-www.cdc.gov/nchs/products/pubs/pubd/series/ser.
htm). Mortality statistics were obtained from CDC's "com-
pressed mortality" database, accessed through CDC WON-
DER (CDC, 2007) (http://wonder.cdc.gov/mortSQL.
html). EPA Regional mortality statistics were generated by
combining and age-adjusting state-by-state totals for each
EPA Region using data from CDC WONDER.
References
American Lung Association. 2004. Chronic obstruc-
tive pulmonary disease (COPD) fact sheet. Accessed
February 7, 2005.
CDC (Centers for Disease Control and Prevention). 2007.
CDC Wide-ranging OnLine Data for Epidemiologic
Research (WONDER). Compressed mortality file, under-
lying cause of death. 1999-2004 (with ICD 10 codes) and
1979-1998 (with ICD 9 codes). Accessed October 2007.
CDC. 2003. Facts about chronic obstructive pulmonary
disease (COPD). Accessed February 7, 2005.
CDC. n.d. CDC WONDER: Help page for compressed
mortality file. Accessed September 2007.
NCHS (National Center for Health Statistics). 2007.
Summary health statistics for U.S. adults: National Health
Interview Survey, 2006. Vital Health Stat. 10(235).
NCHS. 2006a. Summary health statistics for U.S. adults:
National Health Interview Survey, 2005. Vital Health Stat.
10(232).
NCHS. 2006b. Summary health statistics for U.S. adults:
National Health Interview Survey, 2004. Vital Health Stat.
10(228).
NCHS. 2005. Summary health statistics for U.S. adults:
National Health Interview Survey, 2003. Vital Health Stat.
10(225).
NCHS. 2004. Summary health statistics for U.S. adults:
National Health Interview Survey, 2002. Vital Health Stat.
10(222).
NCHS. 2003. Summary health statistics for U.S. adults:
National Health Interview Survey, 2001. Vital Health Stat.
10(218).
NCHS. 2002. Summary health statistics for U.S. adults:
National Health Interview Survey, 2000. Vital Health Stat.
10(215).
NCHS. 2001. Summary health statistics for U.S. adults:
National Health Interview Survey, 1999. Vital Health Stat.
10(212).
NHLBI (National Heart, Lung, and Blood Institute). 2003.
Chronic obstructive pulmonary disease fact sheet. NIH
publication No. 03-5229. Bethesda, MD: U.S. Department
of Health and Human Services,
State of California. 2005. Proposed identification of envi-
ronmental tobacco smoke as a toxic air contaminant. Part B:
Health effects assessment for environmental tobacco smoke.
As approved by the Scientific Review Panel on June 24,
2005. California Environmental Protection Agency, Office
of Environmental Health Hazard Assessment.
5-54
EPA's 2008 Report on the Environment
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Asthma Prevalence
Asthma is a chronic respiratory disease characterized
by inflammation of the airways and lungs. During an
asthma attack, the airways that carry air to the lungs are
constricted, and as a result, less air is able to flow in and
out of the lungs (NHLBI, 2004). Asthma attacks can cause
a multitude of symptoms ranging in severity from mild
to life-threatening. These symptoms include wheezing,
breathlessness, chest tightness, and coughing (NHLBI,
2004). Currently, there is no cure for asthma; however,
people who have asthma can still lead productive lives if
they control their asthma. Taking medication and avoiding
contact with environmental "triggers" can control asthma.
A family history of asthma contributes to susceptibil-
ity, but mostly what causes the development of asthma is
unknown. Environmental exposures such as environmental
tobacco smoke, dust mites, cockroach allergen, outdoor air
pollution (e.g., ozone, particulate matter), pets, and mold are
considered important triggers of an asthma attack (CDC,
2003, 2004; U.S. EPA, 2005, 2007).
Statistics for lifetime diagnosis prevalence, current asthma
prevalence, and asthma attack prevalence are based on national
estimates from the National Health Interview Survey (NHIS),
conducted by the Centers for Disease Control and Preven-
tion's (CDC's) National Center for Health Statistics (NCHS).
The NHIS is the principal source of information on the health
of the civilian non-institutionalized population of the U.S.
and since 1960 has been one of the major data collection pro-
grams of NCHS. For this indicator, lifetime asthma diagnosis
is defined as the number of adults/children who reported that
they had ever been told by a doctor or other health practitio-
ner that they had asthma. To determine current asthma preva-
lence, adults/children who had been told that they had asthma
•were asked whether they still have asthma. Asthma attack
prevalence is based on the number of adults/children who
reported an asthma episode or attack in the past 12 months.
What the Data Show
From 2003 to 2005, approximately 7.3 percent of the
U.S. population reported that they currently have asthma
(NCHS, 2007c). Reported asthma rates are highest in the
child and adolescent population.
Adult Asthma
In adults, an increase in asthma prevalence rates (i.e., life-
time diagnosis) is evident from 1997 to 2001, with some
decrease after 2001 and subsequent increase after 2003
(Exhibit 5-29, panel B). The prevalence rates range from
a low of 85 cases per 1,000 in 1999 to a high of 110 cases
per 1,000 in 2006. Asthma was consistently higher among
adult females than males, with a range of 98 (1999) and
126 (2005) cases per 1,000 in females and 71 (1999) and
95 (2006) cases per 1,000 in males. The asthma prevalence
rate also consistently decreases in older populations. In
2006, the asthma prevalence rates were 115 (ages 18-44
years), 105 (ages 45-64), 117 (ages 65-74 years), and 93 (ages
75+ years) cases per 1,000 (data not shown).
Exhibit 5-30 compares asthma rates across racial and
ethnic groups for the 2003-2005 time period. As shown
in panel A, the lifetime asthma diagnosis in adults was
highest among American Indians/Alaska Natives (131
cases per 1,000), followed by blacks or African Americans
(112 cases per 1,000), whites (100 cases per 1,000), and
lowest among Asians (72 cases per 1,000). This same gen-
eral pattern is seen for current asthma and asthma attack
prevalence. Panel B shows that Hispanics or Latinos had
lower rates across all three asthma prevalence catego-
ries than non-Hispanic whites and non-Hispanic blacks.
For lifetime asthma diagnosis, 77 cases per 1,000 were
reported in Hispanics or Latinos, 106 cases per 1,000 in
non-Hispanic whites, and 111 cases per 1,000 in non-
Hispanic blacks.
Exhibit 5-29. Estimated lifetime asthma diagnosis prevalence in children and adults in the U.S.,
1997-2006ab
A. Children (0-17 years)
Adults (18 years and older)
Year
lifetime asthma diagnosis is determined
by asking survey participants if they
were "ever" told they had asthma.
bRates presented are crude rates.
Data source: NCHS, 2002a-d, 2003a-f,
2004a,b, 2005a,b, 2006a-d, 2007a,b
EPA's 2008 Report on the Environment
5-55
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INDICATOI
Asthma Prevalence (continued)
Exhibit 5-30. Asthma prevalence in the U.S. by race and Hispanic origin, 2003-2005a
A. Asthma prevalence by race
200
160
120
40
Lifetime asthma diagnosis
Current asthma prevalence
Asthma attack prevalence
Children
(0-17 years)
Adults
(18+years)
Children
(0-17 years)
Adults
(18+years)
Children
(0-17 years)
Adults
(18+years)
All groups
White
Black
American Indian/
Alaska Native
Asian
200
160
120
80
40
0
B. Asthma prevalence by Hispanic origin
Lifetime asthma diagnosis
Current asthma prevalence
Asthma attack prevalence
I
•ill
Children
(0-17 years)
Adults
(18+years)
Children
(0-17 years)
Adults
(18+years)
Children
(0-17 years)
Adults
(18+years)
All groups
Hispanic
Non-Hispanic white
Non-Hispanic black
aRates presented for age 0-17 are crude rates; rates presented for age 18 and older are age-adjusted.
lifetime asthma diagnosis is determined by asking survey participants if they were "ever" told that they had asthma.
Current asthma prevalence is determined by asking if the survey participant still has asthma.
dAsthma attack prevalence is determined by asking if the survey participant has had an asthma attack within the past 12 months.
Data source: NCHS, 2007c
Childhood Asthma
In 2006, almost 10 million children within the U.S.
(age 0-17 years) were reported as ever having a diagno-
sis of asthma and nearly 4 million reported experienc-
ing an asthma episode or attack during the previous 12
months. As shown in Exhibit 5-31, asthma prevalence rates
increased approximately 4 percent per year between 1980
and 1996. Rates in subsequent years (1997-2006), reported
in three categories, show no sharp upward or downward
change through most of the time period, although an
increase in current and lifetime reported asthma rates
\vas observed in 2005 and 2006. Lifetime asthma diagno-
sis rates range from a low of 108 cases per 1,000 in 1999
to a high of 135 cases per 1,000 in 2006. Since tracking
began in 2001, current asthma prevalence has ranged from
approximately 83.4 cases per 1,000 (2002) to 93 cases
per 1,000 (2006). Between 1997 and 2006, asthma attack
prevalence rates have varied, with the lowest rate of 52.0
per 1,000 occurring in 2005 and the highest rate of 57.7
cases per 1,000 occurring in 2002. Male children consis-
tently had higher rates of asthma prevalence than female
children (Exhibit 5-29, panel A).
The overall pattern of asthma prevalence across races
in children during 2003-2005 is similar to that seen
in adults (Exhibit 5-30). One notable exception is that
asthma prevalence in black or African American children
\vas higher than asthma prevalence in American Indian/
Alaska Native children, the reverse of what was observed
in the adult population. For example, reported lifetime
asthma diagnosis was highest among black or African
American children (172 cases per 1,000), followed by
American Indians/Alaska Natives (166 cases per 1,000),
•whites (114 cases per 1,000), and Asians (78 cases per
1,000). Hispanic children had lower asthma prevalence
rates for all three categories than non-Hispanic white and
non-Hispanic black children.
5-56
EPA's 2008 Report on the Environment
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INDICATOI
Asthma Prevalence (continued)
Indicator Limitations
• The NHIS questionnaire underwent major changes in 1997,
and the data presented focus on surveys conducted from
1997 to the most currently available release (2004). The
redesigned NHIS is different in content, format, and mode
of data collection from earlier versions of the survey. Due to
changes in methodology, comparisons between 1997-2004
NHIS estimates and pre-1997 NHIS data may not be valid.
• Prevalence data reported in the NHIS are based on
self-reported responses to specific questions pertaining
to airway-related illnesses, and are subject to the biases
associated with self-reported data. Self-reported data may
underestimate the disease prevalence being measured if,
for -whatever reason, the respondent is not fully aware of
his/her condition.
• Except \vhere other-wise noted, all prevalence data are
based on crude rates and are not age-adjusted, as CDC
did not report age-adjusted data prior to 2002 in the data
sources used for this indicator. Therefore, the reported
disease prevalence rates across time or -within different
race and gender subgroups may not reflect differences in
the age distribution of the populations being compared.
Data Sources
Asthma prevalence data -were obtained from annual reports
published by NCHS (NCHS, 2002a-d; 2003a-f; 2004a,b;
2005a,b; 2006a-d; 2007a,b), which summarize health
statistics compiled from the NHIS (http://www.cdc.gov/
nchs/products/pubs/pubd/series/ser.htm#srlO). Race and
ethnicity data -were obtained from CDC's online "Health
Data for All Ages" (NCHS, 2007c) (http://www.cdc.gov/
nchs/health_data_for_all_ages.htm). The data used by CDC
to create the asthma tables in "Health Data for All Ages"
originate from the NHIS. The pre-1997 data also originate
from the NHIS, as compiled by NCHS in Akmbami (2006).
References
Akinbami, LJ. 2006. The state of childhood asthma,
United States, 1980-2005. Advance data from vital and
health statistics. Number 381. Hyattsville, MD: National
Center for Health Statistics.
CDC (Centers for Disease Control and Prevention). 2004.
Asthma's impact on children and adolescents. Accessed
November 22, 2004.
CDC. 2003. Basic facts about asthma. Accessed February
3, 2005.
NCHS (National Center for Health Statistics). 2007a.
Summary health statistics for U.S. adults: National Health
Interview Survey, 2006. Vital Health Stat. 10(235).
Exhibit 5-31. Asthma prevalence in U.S.
children (0-17 years), 1980-2006a
'82 '84 '86 '88 '90 '92 '94 '96 '98 '00 '02 '04 '06
Year
aDue to changes in NHIS questions in 1997, asthma prevalence data
collected from 1980-1996 are not directly comparable to the data
collected from 1997-2004.
lifetime asthma diagnosis is determined by asking survey
participants if they were "ever" told their child has asthma.
Current asthma prevalence is determined by asking if the child still
has asthma.
d Asthma attack prevalence is determined by asking if the child has
had an asthma attack within the past 12 months.
Data source: Adapted from Akinbami, 2006; NCHS, 2007b
NCHS. 2007b. Summary health statistics for U.S. chil-
dren: National Health Interview Survey, 2006. Vital
Health Stat. 10(234).
NCHS. 2007c. Health data for all ages. Accessed Septem-
ber 2007.
NCHS. 2006a. Summary health statistics for U.S. adults:
National Health Interview Survey, 2005. Vital Health Stat.
10(232).
NCHS. 2006b. Summary health statistics for U.S. chil-
dren: National Health Interview Survey, 2005. Vital
Health Stat. 10(231).
NCHS. 2006c. Summary health statistics for U.S. adults:
National Health Interview Survey, 2004. Vital Health Stat.
10(228).
EPA's 2008 Report on the Environment
5-57
-------
INDICATOR
Asthma Prevalence (continued)
NCHS. 2006d. Summary health statistics for U.S. chil-
dren: National Health Interview Survey, 2004. Vital
Health Stat. 10(227).
NCHS. 2005a. Summary health statistics for U.S. adults:
National Health Interview Survey, 2003. Vital Health Stat.
10(225).
NCHS. 2005b. Summary health statistics for U.S. children:
National Health Interview Survey, 2003. Vital Health Stat.
10(223).
NCHS. 2004a. Summary health statistics for U.S. adults:
National Health Interview Survey, 2002. Vital Health Stat.
10(222).
NCHS. 2004b. Summary health statistics for U.S. children:
National Health Interview Survey, 2002. Vital Health Stat.
10(221).
NCHS. 2003a. Summary health statistics for U.S. adults:
National Health Interview Survey, 2001. Vital Health Stat.
10(218).
NCHS. 2003b. Summary health statistics for U.S. children:
National Health Interview Survey, 2001. Vital Health Stat.
10(216).
NCHS. 2003c. Summary health statistics for U.S. adults:
National Health Interview Survey, 2000. Vital Health Stat.
10(215).
NCHS. 2003d. Summary health statistics for U.S. chil-
dren: National Health Interview Survey, 2000. Vital
Health Stat. 10(213).
NCHS. 2003e. Summary health statistics for U.S. adults:
National Health Interview Survey, 1999. Vital Health Stat.
10(212).
NCHS. 2003E Summary health statistics for U.S. children:
National Health Interview Survey, 1999. Vital Health Stat.
10(210).
NCHS. 2002a. Summary health statistics for U.S. adults:
National Health Interview Survey, 1998. Vital Health Stat.
10(209).
NCHS. 2002b. Summary health statistics for U.S. children:
National Health Interview Survey, 1998. Vital Health Stat.
10(208).
NCHS. 2002c. Summary health statistics for U.S. adults:
National Health Interview Survey, 1997. Vital Health Stat.
10(205).
NCHS. 2002d. Summary health statistics for U.S. chil-
dren: National Health Interview Survey, 1997. Vital
Health Stat. 10(203).
NHLBI (National Heart, Lung, and Blood Institute). 2004.
Diseases and conditions index. Accessed November 12,
2004.
U.S. EPA (United States Environmental Protection
Agency). 2007. Review of the National Ambient Air
Quality Standards for ozone: policy assessment of scientific
and technical information. OAQPS Staff Paper.
U.S. EPA. 2005. Review of the National Ambient Air
Quality Standards for particulate matter: Policy assessment
of scientific and technical information. OAQPS StaffPaper.
5-58
EPA's 2008 Report on the Environment
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Infectious Diseases Associated with Environmental
Exposures or Conditions
Infectious diseases are human illnesses caused by viruses,
bacteria, parasites, fungi, and other microbes. They can be
spread by direct contact with an infected person or animal,
through ingestion of contaminated food or water, by insects
like mosquitoes or ticks (disease vectors), or by contact with
contaminated surroundings like animal droppings or con-
taminated air. Demographic and environmental factors such
as population growth, increased urbanization, and alteration
of habitats of disease-carrying insects and animals (e.g., irri-
gation, deforestation) may promote the spread of infectious
diseases (CDC, 1998a). The three broad infectious disease
categories included here are those whose appearance and
spread may be influenced to some extent by environmental
conditions and change. They include gastrointestinal (GI)
disease, arthropod-borne disease, and legionellosis.
• Gastrointestinal diseases. Eight notifiable GI diseases
caused by microorganisms are discussed below: chol-
era, cryptosporidiosis, Escherichia coli (E. coli) O157:H7,
giardiasis, hepatitis A, salmonellosis, shigellosis, and
typhoid fever. The major environmental source of gas-
trointestinal illness is water or food that is contaminated
•with pathogenic microorganisms. The primary means of
transmission for these eight diseases is through ingestion
of contaminated food/water or through contact with and
accidental ingestion of fecal matter (CDC, 2005a).
• Arthropod-borne diseases. Three arthropod-borne
diseases are included: Lyme disease (transmission of
Borrelia burgdorferi by ticks), Rocky Mountain spotted
fever (transmission of Rickettsia rickettsii by ticks), and
West Nile virus (transmitted by mosquitoes). Certain
ticks and mosquitoes (arthropods) can carry bacteria and
viruses that cause disease in humans. The arthropods
acquire the bacteria or viruses when they bite an infected
mammal or bird. Some studies indicate that spread of
vector-borne disease may be influenced by land use and/
or other environmental change (CDC, 2004). In recent
years, both Lyme disease and West Nile virus have spread
across the U.S. (CDC, 1993, 2000, 2004). Surveillance
for Lyme disease was initiated by the Centers for Disease
Control and Prevention (CDC) in 1982 (CDC, 1993).
• Legionellosis. Legionellosis, or Legionnaires' disease,
is a serious and sometimes fatal form of pneumonia. It is
caused by Legionella bacteria, which are found naturally
in the environment and thrive in warm water and warm
damp places. They are commonly found in lakes, riv-
ers, creeks, hot springs, and other bodies of water. This
bacterium has been associated with outbreaks in the U.S.
linked to poorly maintained artificial water systems (e.g.,
air conditioning and industrial cooling systems) and air
ventilation systems. Infection results from inhalation of
contaminated water sprays or mists (CDC, 2003a).
This indicator reflects occurrence of these notifiable
diseases as reported by health departments to the National
Notifiable Diseases Surveillance System (NNDSS). A noti-
fiable disease is one for which regular, frequent, and timely
information regarding individual cases is considered neces-
sary for the prevention and control of the disease (CDC,
2005b). Data are collected by all 50 states, five territories,
New York City, and the District of Columbia, based on a
list of recommended nationally notifiable infectious dis-
eases, and compiled nationally. The temporal coverage of
the data varies by disease. The number of states reporting
may also vary. For example, in 1995, when cryptosporidi-
osis was first nationally reported, only 27 states reported;
45 states reported this disease by 1997.
What the Data Show
Gastrointestinal Diseases
Exhibits 5-32 and 5-33 present the number of reported cases
for each of the eight notifiable GI diseases from 1995-2005.
In comparison to the other GI diseases, the number of newly
identified cholera cases reported each year is low. From 1995
to 2005, just 81 laboratory-confirmed cases of cholera were
reported to CDC, with eight cases being reported in 2005,
the most current reporting year. Of these 81 total cases, 51
(63 percent) were acquired outside the U.S. The number of
newly identified cases of typhoid fever was relatively stable
from 1995 to 2005, ranging between a low of 321 cases in
2002 and a high of 396 cases in 1996. In 2005, 324 cases of
typhoid fever were reported. Hepatitis A has continued to
decline, with 31,582 cases reported in 1995 compared to
4,488 cases in 2005. The number of reported cryptosporidi-
osis cases increased in 2005 (5,659 cases). Fewer shigellosis
cases were reported in 2004 and 2005 than in preceding
years. No notable changes in the number of cases were
observed for E. coli O157:H7, giardiasis (only 4 years of
reporting data available), and salmonellosis.
Arthropod-Borne Diseases
Exhibit 5-34 presents the number of reported cases for
three arthropod-borne diseases. Lyme disease is the most
commonly reported arthropod-borne disease in the U.S.,
•with 23,305 cases reported in 2005, just under the record
number reported in 2002 (23,763 cases). CDC began
surveillance of Rocky Mountain spotted fever in 1970.
The number of new cases of Rocky Mountain spotted
fever reported from 1995 to 2005 has fluctuated, rang-
ing between a low of 365 cases in 1998 and a high of
1,936 cases in 2005. Cases of West Nile virus were first
documented in the U.S. in 1999. A total of 80 cases were
reported in 1999 (62 cases) and 2000 (18 cases) (data not
shown). West Nile virus became nationally reportable in
2002, and the number of reported cases rose from 2,840 in
EPA's 2008 Report on the Environment
5-59
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INDICATOR
Infectious Diseases Associated with Environmental
Exposures or Conditions (continued)
Exhibit 5-32. Number of reported cases of gastrointestinal diseases in the U.S., 1995-2005 (part 1)
l
6,000
5,000
4,000
3,000
2,000
1,000
0
Cryptosporidiosis
£ co//0157:H7
25
1 20
re
2 15
o
o 10
_Q
I 5
== 0
Cholera
'95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05
Year
Typhoid fever
'95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05
Year
Data source: CDC, 1996, 1997, 1998b, 1999, 2001, 2002, 2003b, 2004, 2005b, 2006, 2007
Exhibit 5-33. Number of reported cases of gastrointestinal diseases in the U.S., 1995-2005 (part 2)
50,000
40,000
o 30,000
20,000
10,000
Giardiasis
Hepatitis A
Salmonellosis
Shigellosis
'02 '03'04'05 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04'05 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04'05
Year
aGiardiasis was not on CDC's list of nationally notifiable infectious diseases prior to 2002.
Data source: CDC, 1996, 1997, 1998b, 1999, 2001, 2002, 2003b, 2004, 2005b, 2006, 2007
2002 to 2,866 in 2003. In 2004, the number of reported
cases decreased to 1,142; the number increased to 1,309
reported cases in 2005.
Legionellosis
Exhibit 5-35 presents the number of reported cases of
legionellosis within the U.S. population from 1995 to
2005. From 1995 to 2002, the number of new cases of
legionellosis was relatively stable, ranging from a low
of 1,108 cases in 1999 to 1,355 cases in 1998. However,
an increased number of new cases was reported in 2003
(2,232), 2004 (2,093), and 2005 (2,301).
Indicator Limitations
• State health departments report cases of notifiable dis-
eases to CDC; policies for reporting can vary by disease
or reporting jurisdiction.
• Disease reporting likely underestimates the actual number
of cases for a given time period because reporting nation-
ally notifiable diseases to CDC is voluntary. Additionally,
the completeness of reporting likely varies by disease. The
degree of completeness of data reporting is influenced by
many factors such as the diagnostic facilities available, the
control measures in effect, public awareness of a specific
5-60
EPA's 2008 Report on the Environment
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Infectious Diseases Associated with Environmental
Exposures or Conditions (continued)
Exhibit 5-34. Number of reported cases of arthropod-borne diseases in the U.S., 1995-2005
25,000
20,000
15,000
10,000
5,000
Lyme disease
Rocky Mountain spotted fever
West Nile virus
'95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05
'02 '03 '04 '05
Year
aWest Nile virus was not on CDC's list of nationally notifiable infectious diseases prior to 2002.
Data source: CDC, 1996, 1997, 1998b, 1999, 2001, 2002, 2003b, 2004, 2005b, 2006, 2007
disease, and the interests, resources, and priorities of state
and local officials responsible for disease control and public
health surveillance (CDC, 2007).
• Factors such as changes in case definitions for public
health surveillance, introduction of new diagnostic tests,
or discovery of new disease entities can cause changes
in disease reporting that are independent of the true inci-
dence of disease (CDC, 2004).
• Prior to 2005, only confirmed "neuroinvasive" cases of
West Nile virus—the most severe form of the condi-
tion—were reported (CDC, 2005c). Beginning in 2005,
non-neuroinvasive domestic arboviral diseases for the
six domestic arboviruses listed were added to the list of
nationally notifiable diseases; these included West Nile
fever, a non-neuroinvasive form of West Nile virus (CDC,
2007). In order to maintain reporting consistency, only
neuroinvasive cases are presented for this indicator.
Data Sources
The data for this indicator were obtained from CDC
annual reports that summarize data on nationally notifiable
infectious diseases reported to CDC by state health agen-
cies across the country (CDC, 1996, 1997, 1998b, 1999,
2001, 2002, 2003b, 2004, 2005b, 2006, 2007). Data are
collected and compiled from reports sent by state health
departments to the NNDSS, which is operated by CDC.
The NNDSS is neither a single surveillance system nor a
method of reporting. Certain NNDSS data are reported
to CDC through separate surveillance information systems
and through different reporting mechanisms; however,
these data are aggregated and compiled for publication
purposes (CDC, 2007).
References
CDC (Centers for Disease Control and Prevention). 2007.
Summary of notifiable diseases—United States, 2005.
MMWR 54(53). See Table 1.
Exhibit 5-35. Number of reported cases of
legionellosis in the U.S., 1995-2005
2,500
2,000
5 1,500
-S 1,000
500
'95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05
Year
Data source: CDC, 1996, 1997, 1998b, 1999, 2001, 2002, 2003b,
2004, 2005b, 2006, 2007
EPA's 2008 Report on the Environment
5-61
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INDICATOR
Infectious Diseases Associated with Environmental
Exposures or Conditions (continued)
CDC. 2006. Summary of notifiable diseases—United
States, 2004. MMWR 53(53). See Table 1.
CDC. 2005a. Foodborne illness—frequently asked
questions. Accessed April 11, 2005.
CDC. 2005b. Summary of notifiable diseases—United
States, 2003. MMWR 52(54). See Table 1.
CDC. 2005c. West Nile virus statistics, surveillance, and
control: 2005 West Nile virus activity in the United States.
Accessed October 16, 2005.
CDC. 2004. Summary of notifiable diseases—United
States, 2002. MMWR 51(53). See Table 1.
CDC. 2003a. Legionnaires' disease fact sheet. Accessed
October 20, 2005.
CDC. 2003b. Summary of notifiable diseases—United
States, 2001. MMWR 50(53). See Table 1.
CDC. 2002. Summary of notifiable diseases—United
States, 2000. MMWR 49(53). See Table 1.
CDC. 2001. Summary of notifiable diseases—United
States, 1999. MMWR 48(53). See Table 1.
CDC. 2000. Update: West Nile virus activity—eastern
United States, 2000. MMWR 49(46):1044-1047.
CDC. 1999. Summary of notifiable diseases—United
States, 1998. MMWR 47(53).
CDC. 1998a. Preventing emerging infectious diseases. A
strategy for the 21st century.
CDC. 1998b. Summary of notifiable diseases—United
States, 1997. MMWR 46(54).
CDC. 1997. Summary of notifiable diseases—United
States, 1996. MMWR 45(53).
CDC. 1996. Summary of notifiable diseases—United
States, 1995. MMWR 44(53).
CDC. 1993. Lyme disease—United States, 1991-1992.
MMWR 42(18):345-348.
INDICATO
Birth Defects Prevalence and Mortality
Birth defects are structural or functional anomalies causing
physical or mental disability, some of which can be fatal.
Although birth defects are the leading cause of infant mor-
tality (deaths occurring to those under 1 year of age) in the
U.S., the cause is unknown for approximately 70 percent of
all cases (Infant Mortality indicator, p. 5-36) (CDC, 2005).
Many different factors may be associated with the develop-
ment of birth defects, such as genetic and/or chromosomal
aberrations, in utero exposure to viruses or bacteria, uncon-
trolled maternal diabetes, maternal cigarette smoke, mater-
nal use of drugs and alcohol during pregnancy, and prenatal
exposure to chemicals. All of these factors may influence
normal infant growth or development, resulting in different
types of birth defects (NICHD, 2006).
This indicator presents birth defects prevalence at birth
and mortality rates among infants in the U.S. as recorded
in the National Vital Statistics System, which registers
virtually all births and deaths nation-wide. Data collection
began in 1933 and is available through 2004. Birth defects
data are collected on death certificates from all 50 states
and the District of Columbia and recorded on birth certifi-
cates for 49 states and the District of Columbia. Reported
race and ethnicity data are based on the race and ethnicity
of the mother.
What the Data Show
Exhibit 5-36 presents the prevalence of live births with
identified specific congenital anomalies (i.e., birth defects)
between 1999 and 2004. The most frequently occurring
5-62
EPA's 2008 Report on the Environment
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INDICATOI
Birth Defects Prevalence and Mortality (continued)
Exhibit 5-36. Prevalence of live births in
1 999-20043
Overall rate
Central nervous system anomalies
Anencephalus
Spina bifida/meningocele
Hydrocephalus
Microcephalus
Other central nervous system anomalies
Circulatory/respiratory anomalies
Heart malformations
Other circulatory/respiratory anomalies
Gastrointestinal anomalies
Rectal atresia/stenosis
Tracheo-esophageal fistula/esophageal atresia
Omphalocele/gastroschisis
Other gastrointestinal anomalies
Urogenital anomalies
Malformed genitalia
Renal agenesis
Other urogenital anomalies
Chromosomal anomalies
Cleft lip/palate
Polydactyly/syndactyly/adactyly
Clubfoot
Diaphragmatic hernia
Other musculoskeletal/integumental anomalies
Down's syndrome
Other chromosomal anomalies
the U.S. with
1999
1,170.2 1,
11.0
20.1
21.5
5.9
20.0
119.8
140.6
9.0
13.3
30.2
29.8
76.3
13.7
99.0
80.9
87.9
55.7
13.1
239.9
45.5
36.9
specific
2000
164.2
10.7
20.7
23.7
7.2
20.7
124.9
138.1
8.4
12.1
29.7
29.9
84.2
13.8
99.3
82.1
87.2
57.2
10.8
217.0
46.9
39.7
birth defects
2001
1,178.8 1
9.9
19.9
22.5
5.6
24.8
122.5
139.6
9.0
12.0
31.8
34.2
88.4
14.8
102.8
80.6
82.4
58.6
11.4
226.4
45.5
36.2
(congenita
2002
,170.6 1
9.9
20.0
22.5
5.5
22.2
129.9
131.7
8.3
10.8
30.3
36.1
86.6
15.4
101.8
78.5
82.2
59.6
12.1
228.9
46.7
31.6
anomalies),
2003 2004
103.4 1,111.8
11.4 10.9
18.7 19.3
22.2 22.4
5.6 6.9
21.1 21.5
128.9 137.7
126.1 135.3
7.8 8.7
10.8 11.8
32.5 31.9
33.0 33.9
79.7 80.8
14.0 13.6
90.2 89.5
75.9 77.7
76.4 74.8
57.6 55.7
11.4 10.4
208.2 211.1
46.5 47.9
30.1 29.3
"Rates are per 100,000 live births.
Data source: NCHS, 2001, 2002a,b, 2003, 2005, 2006; CDC, 2007a
types of birth defects were various musculoskeletal/integu-
mental anomalies, circulatory/respiratory system anomalies,
and heart malformations. In 2004, heart malformations
occurred at a rate of 137.7 per 100,000 live births, which was
highest among the specific anomalies listed (i.e., categories
that do not include "other"). The overall rate of birth defects
(i.e., all birth defects combined) has been relatively stable
between 1999 and 2002, with a noticeable decline in 2003
and 2004. Blacks have a consistently higher rate of birth
defects than whites during this time period, with a rate of
1,337.5 (blacks) compared with 1,064.0 (whites) birth defects
per 100,000 live births in 2004 (data not shown).
Rates for certain types of anomalies differ widely with
maternal age. For example, in 2004 as in past years, infants
of the youngest mothers (under 20 years of age) have the
highest rates for omphalocele/gastroschisis, a defect or
abnormality of the anterior abdominal wall (87.1 per 1,000
live births); infants of mothers age 35 years and over have
the highest rates for Down's syndrome (348.3 per 1,000
live births). (Data not shown.)
EPA's 2008 Report on the Environment
5-63
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INDICATOR
Birth Defects Prevalence and Mortality (continued)
Birth defects continue to be the leading cause of infant
mortality, accounting for 5,622 (20.1 percent) of the 27,936
infant deaths in 2004 (Exhibit 5-16, Infant Mortality
indicator, p. 5-37). Between 1979 and 1998, a decline in
the national birth defects mortality rate has been observed,
ranging from 255.4 per 100,000 live births in 1979 to
157.6 per 100,000 live births in 1998. From 1999 to 2004,
the birth defects mortality rates were 144.2 (1999), 150.9
(2000), 136.7 (2001), 139.4 (2002), 140.4 (2003), and 137.9
(2004) per 100,000 live births. (Data not shown.)
Birth defects mortality was consistently higher among
black infants than white infants. In 2004, for example,
mortality attributed to birth defects among black male and
female infants was 169.9 and 155.6 per 100,000 infants,
respectively; among white male and female infants, it was
134.3 and 134.7 per 100,000 infants, respectively. (Data
not shown.)
Indicator Limitations
• Because some birth defects are not recognized imme-
diately, they are often underreported on both birth and
death certificates (Friis and Sellers, 1999). Many anomalies
are hard to detect at birth, which limits early ascertain-
ment and complete reporting. The most serious and/or
apparent anomalies are more likely to be identified and
reported prior to hospital discharge (Honein et al., 2001).
• The lack of uniform reporting on birth certificates intro-
duces additional uncertainty. For example, race informa-
tion may be missing or incomplete. Also, beginning in
2003, two states began using a revised "standard certifi-
cate of live birth;" therefore, a subset of anomaly data
\vas excluded because of the lack of comparability with
other data sets (NCHS, 2005).
• The congenital anomalies reported on birth certificates
are rare events. Since a small change in the number of
anomalies reported can result in a relatively large change
in rates, caution should also be used in comparing yearly
rates for a specific anomaly.
• The birth defects anomaly groupings that include "other"
(e.g., other musculoskeletal anomalies) include a large
number of non-specific birth defects and should be con-
sidered separately from the specific birth defects listed.
• Birth defects mortality rates are based on underly-
ing cause of death as entered on a death certificate by a
physician. Incorrect coding and low rates of autopsies
that confirm the cause of death may occur. Addition-
ally, some individuals may have had competing causes
of death. "When more than one cause or condition is
entered by the physician, the underlying cause is deter-
mined by the sequence of conditions on the certificate,
provisions of the ICD [International Classification of
Diseases], and associated selection rules and modifica-
tions" (CDC, n.d.). Consequently, some misclassification
of reported mortality might occur in individuals with
competing causes of death, as well as underreporting of
some birth defects as the cause of death.
• The International Classification of Diseases 9th Revision
(ICD-9) codes were used to specify underlying cause of
death for years 1979-1998. Beginning in 1999, cause of
death is specified with the International Classification of
Diseases 10th Revision (ICD-10) codes. The two revi-
sions differ substantially, and to prevent confusion about
the significance of any specific disease code, data queries
are separate. The relatively large difference between birth
defects mortality rates reported from 1979 through 1998
and those reported beginning in 1999 may be due to some
changes in the criteria used to report birth defects mortal-
ity during the switch from ICD-9 to ICD-10.
Data Sources
The birth defects rate data used for this indicator are from
National Vital Statistics Reports published by the CDC's
National Center for Health Statistics (NCHS, 2001,
2002a,b, 2003, 2005, 2006). CDC's "VitalStats"—a collec-
tion of vital statistics products including tables, data files,
and reports that allow users to access and examine vital
statistics and population data interactively—were used to
obtain specific anomaly data for 2004 (CDC, 2007a). The
birth defects mortality data were obtained from a pub-
lished report by the National Center for Health Statistics
(NCHS, 2007) and from CDC's compressed mortality files
(underlying cause of death), accessed via CDC WONDER
(CDC, 2007b), at http://wonder.cdc.gov.
References
CDC (Centers for Disease Control and Prevention). 2007a.
VitalStats. National Center for Health Statistics. Accessed
October 17, 2007.
CDC. 2007b. CDC Wide-ranging OnLme Data for Epi-
demiologic Research (WONDER). Compressed mortality
file, underlying cause of death. 1999-2004 (with ICD 10
codes) and 1979-1998 (with ICD 9 codes). Accessed 2007.
CDC. 2005. Birth defects. Accessed September 2007.
CDC. n.d. CDC WONDER: Help page for compressed
mortality file. Accessed September 2007.
Friis, R.H., and T.A. Sellers. 1999. Epidemiology for
public health practice. Second edition. Gaithersburg, MD:
Aspen Publishers.
5-64
EPA's 2008 Report on the Environment
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INDICATOI
Birth Defects Prevalence and Mortality (continued)
Honein, M.A., LJ. Paulozzi, andM.L. Watkms. 2001.
Maternal smoking and birth defects: Validity of birth data
for effect estimation. Public Health Reports 116:327-335
NCHS (National Center for Health Statistics). 2007.
Deaths: Final data for 2004. National Vital Statistics
Reports 55(19).
NCHS. 2006. Births: Final data for 2004. National Vital
Statistics Reports 55(1). See Table 25.
NCHS. 2005. Births: Final data for 2003. National Vital
Statistics Reports 54(2). See Table 49.
NCHS. 2003. Births: Final data for 2002. National Vital
Statistics Reports 52(10). See Table 49.
NCHS. 2002a. Births: Final data for 2001. National Vital
Statistics Reports 51(2). See Table 49.
NCHS. 2002b. Births: Final data for 2000. National Vital
Statistics Reports 50(5). See Table 49.
NCHS. 2001. Births: Final data for 1999. National Vital
Statistics Reports 49(1). See Table 49.
NICHD (National Institute of Child Health and Human
Development). 2006. Birth defects and developmental
disabilities. Accessed September 2007.
ow Birthweigh
The term "low birthweight" (LEW) is typically used
for any infant weighing less than 2,500 grams at birth.
Weight is a critical health measure because LEW children are
more prone to death and disability than their counterparts.
The etiology of LEW for term-LBW (born after 37+
•weeks of gestation) infants and preterm-LBW (born after
less than 37 weeks of gestation) infants differs. For term-
LBW infants, underlying causes include factors such as
maternal smoking, weight at conception, and gestational
•weight gain, whereas for preterm-LBW infants, the etiol-
ogy largely remains unexplained (CDC, 1994). Various
exposures have been implicated as risk factors for term-
LBW (e.g., maternal smoking, maternal exposure to lead,
diethylstilbestrol, occupational exposures) (Sram et al.,
2005; Kiely et al., 1994). The potential effect of air pollu-
tion on LEW continues to be researched (e.g., particulate
matter, carbon monoxide, ozone).
This indicator presents the percentage of LEW infants
born in the U.S. based on natality data reported to the
National Vital Statistics System (NVSS). The NVSS reg-
isters virtually all deaths and births nation-wide, with data
coverage from 1933 to 2004 and from all 50 states and the
District of Columbia.
The data presented are based on singleton births only.
This \vas done to eliminate the effect of multiple births.
The data are presented across three maternal age groups
(under 20 years, 20-39 years, and 40 years and older).
Additionally, the data are stratified and reported for
preterm (less than 37 weeks) and full-term (37 weeks and
over) births because of the strong association between
birth-weight and gestational age.
What the Data Show
As expected, the percent of total LEW deliveries among
preterm births is much higher than the percent of total
LEW deliveries among full-term births across each of the
three maternal age categories (Exhibits 5-37 and 5-38).
In general, small differences in the percent of LEW babies
among maternal age categories are evident for both pre- and
full-term births. For example, in 2004, the frequency of
LEW babies among full-term births for mothers less than
20 years old (4.0 percent) is almost 1 percent higher than for
mothers -who are 40 years and older (3.2 percent) and about
1.4 percent higher than for mothers who are in the 20-39
age group (2.4 percent) (Exhibit 5-38).
Among the full-term births, black -women had consis-
tently higher frequencies of LEW babies compared to any
of the other racial groups reported from 1995 and 2004.
This racial pattern is evident in 2004 for all three maternal
age groups, and the difference is most apparent in the 40
and older age group (6.2 percent for blacks and 2.7 percent
for whites) (Exhibit 5-38).
The percentages of term-LBW babies among the other
two racial groups reported in 2004, Native Americans and
Asians/Pacific Islanders, -were 4.1 percent and 3.3 percent,
respectively, for the 40 and older age group. In 2004, some
EPA's 2008 Report on the Environment
5-65
-------
INDICATOR
Low Birth weight (continued)
Exhibit 5-37. Percent of low birthweight infants (<2,500 grams) born preterm in the U.S. by mother's
race and age, 1995-2004ab
A. Mothers <20 years
B. Mothers 20-39 years
C. Mothers 40+years
50
40i
§ 30
H
20
10
0
'£
"Preter
"Data r
Data
' ' '
.-^-^^
Z-l—^—Z^f^
5 '96 '97 '98 '99 '00 '01 '02 '03 '04 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '95 '96 '97 '98 '99 '
Year
m births are births occurring at<37 weeks gestation.
epresent singleton births only.
source: CDC, 2007
~-^---^^
00 '01 '02 '03 '04
•«• All groups
* Black
» White
Exhi
race
10
9
8
7
~ 6
| 5
of 4,
2
1
0
'9
aFull-t
bData
Data
bit 5-38. Percent of low birthweight infants (<2,500 grams) born full-term in the U.S. by mother's
and age, 1995-2004ab
A. Mothers <20 years B. Mothers 20-39 years C. Mothers 40+ years
~^-*^
5 '96 '97 '98 '99 '00 '01 '02 '03 '04 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '95 '96 '97 '98 '99 '
Year
erm births are births occurring at > 37 weeks gestation.
represent singleton births only.
source: CDC, 2007
00 '01 '02 '03 '04
•«• All groups
-•- Black
~ White
variation in the frequency of term-LEW was reported for
Native Americans and Asian/Pacific Islanders among the
three different age groups reported (under 20 years, 20-39
years, and 40 years and older), with Asian/Pacific Island-
ers showing the highest percentage of LEW babies (4.7
percent) among the under 20 year age group and Native
Americans showing the highest percentage of LEW babies
(4.1 percent) among women 40 years and older. Hispanic
•women and non-Hispanic women had similar frequencies
of LEW babies. For example, in 2004, the percent of LEW
babies for Hispanic women was 2.4 percent compared to
2.7 percent for non-Hispanic women. (Data not shown.)
Indicator Limitations
• Complete reporting of natality indicators such as LEW
may vary due to differences in the reporting requirements
established by each state. In some states, the number of
LEW babies may be underreported.
5-66
EPA's 2008 Report on the Environment
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INDICATOI
Low Birth weight (continued)
Data Source
The data used for this indicator were public-use natality
data (1995-2002 and 2003-2004) obtained from the Centers
for Disease Control and Prevention's National Center for
Health Statistics, Division of Vital Statistics, available via
CDC WONDER (CDC, 2007), at http://wonder.cdc.gov.
References
CDC (Centers for Disease Control and Prevention). 2007.
CDC Wide-ranging OnLine Data for Epidemiologic
Research (WONDER). Natality public-use data. Accessed
October 2007.
CDC. 1994. Increasing incidence of low birthweight—
United States, 1981-1991. MMWR 43:335-339.
Kiely, J.S., K.M. Brett, S. Yu, and D.L. Rowley. 1994. Low
birth-weight and intrauterine growth retardation. In: Wilcox,
L.S., and J.S. Marks, eds. From data to action: CDC's public
health surveillance for women, infants, and children. CDC's
maternal and child health monograph 1994. Atlanta, GA:
Centers for Disease Control and Prevention.
Sram R.J., B. Bmkova, J. Dejmek, and M. Bobak. 2005.
Ambient air pollution and pregnancy outcomes: A review
of the literature. Environ. Health Perspect. 113(4):375-382.
INDICATOR
Preterm Delivery
Preterm delivery is defined as delivery prior to 37 weeks
of gestation (a typical pregnancy lasts 40 weeks). The
shorter the gestational age of an infant, the more likely
(s)he is to suffer adverse effects. Preterm birth along with
low birthweight is the second leading cause of infant death
(Infant Mortality indicator, p. 5-36) (NCHS, 2004, 2006),
and accounts for nearly half of all congenital neurological
defects, such as cerebral palsy, and more than two-thirds of
infant deaths (Goldenberg and Rouse, 1998; NCHS, 2006).
The determinants of preterm births are not fully known
and the causes are often multi-factorial. Maternal high-
risk conditions (e.g., infertility problems, vaginal spot-
ting, inadequate maternal weight gain), previous history,
socioeconomic status, smoking, alcohol consumption
before third trimester, and multiple gestation pregnancy
are known risk factors for preterm delivery. Environmental
contaminants (e.g., lead, environmental tobacco smoke, air
pollution) continue to be studied to better understand the
strength of the associations with preterm delivery.
This indicator presents the proportion of U.S. infants
born prior to 37 weeks of gestation, based on natality data
reported to the National Vital Statistics System (NVSS). The
NVSS registers virtually all deaths and births nation-wide,
•with data coverage from 1933 to 2004 and from all 50 states
and the District of Columbia. The data presented here on
preterm delivery were based on singleton births only. This
•was done to eliminate the effect of multiple births. The data
are presented across three maternal age groups (under 20
years, 20-39 years, and 40 years and older).
What the Data Show
The proportion of infants defined as preterm has risen 18
percent since 1990 (NCHS, 2006). A small overall increase
in preterm births has been observed from 1995 (9.8 percent)
Exhibit 5-39. Preterm deliveries in the U.S. by
mother's age and race, 1995-2004ab
A. Preterm deliveries by mother's age
•••All groups
••- <20 years
* 20-39 years
•*- 40+years
'96 '97 '98 '99 '00 '01 '02 '03 '04
Year
B. Preterm deliveries by mother's race
•«• All groups
Black
* White
2
0
'95 '96 '97 '98 '99 '00 '01 '02 '03 '04
Year
aPreterm deliveries are births occurring at <37 weeks gestation.
bData represent singleton births only.
Data source: CDC, 2007
EPA's 2008 Report on the Environment
5-67
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INDICATOR
Preterm Delivery (continued)
to 2004 (10.8 percent). The largest percent increase between
1995 and 2000 has occurred among mothers in the 40 and
over age group, with the percent of preterm births ranging
from 12.0 (1995) to 13.5 percent (2004). The next largest
percent increase was observed in the 20-39 year old mater-
nal group, ranging from 9.2 percent (1996) to 10.3 percent
(2004), with little overall change over time among those
under 20 years of age (Exhibit 5-39, panel A).
In 1995, the percent of preterm births was almost twice
as high among black mothers as among white mothers (16.4
versus 8.5 percent) (Exhibit 5-39, panel B). From 1995 to
2004, preterm delivery among black mothers decreased
slightly: from 16.4 percent in 1995 to 15.9 percent in 2001,
•where the percentage has remained the same through 2004.
During the same time, preterm delivery among white
mothers increased slightly, rising from 8.5 percent in 1995
to 9.9 percent in 2004, resulting in a slight narrowing of
the difference in the preterm birth rate between black and
•white mothers. Preterm delivery for Hispanic mothers
ranged from 10.1 (1995) to 10.9 percent (2004), compared
to 9.7 (1996) and 10.7 (2004) percent for non-Hispanic
mothers between 1995 and 2004. (Data not shown.)
Indicator Limitations
• The primary measure used to determine the gestational
age of the newborn is the interval between the first day
of the mother's last normal menstrual period (LMP) and
the date of birth. This measurement is subject to error
for reasons such as imperfect maternal recall or misiden-
tification of the LMP because of postconception bleed-
ing, delayed ovulation, or intervening early miscarriage.
When the LMP and date of birth are clearly inconsistent
•with the infant's birthweight or plurality, then a "clinical
estimate of gestation" is used. Problems with reporting
gestational age persist and may occur more frequently
among some subpopulations and among births with
shorter gestations (NCHS, 2006).
Data Source
The data used for this indicator were public-use natality
data (1995-2002 and 2003-2004) obtained from the Centers
for Disease Control and Prevention's National Center for
Health Statistics, Division of Vital Statistics, available via
CDC WONDER (CDC, 2007), at http://wonder.cdc.gov.
References
CDC (Centers for Disease Control and Prevention). 2007.
CDC Wide-ranging OnLine Data for Epidemiologic
Research (WONDER). Natality data query. Accessed
October 2007.
Goldenberg, R.L. and DJ. Rouse. 1998. Prevention of
premature birth. New Engl. J. Med. 339:313-320.
NCHS (National Center for Health Statistics). 2006.
Births: Final data for 2004. National Vital Statistics
Reports 55(1).
NCHS. 2004. Infant mortality statistics from the 2002
period linked birth/infant death data set. National Vital
Statistics Reports 53(10).
5.4.3 Discussion
What These Indicators Say About Trends in
Human Disease and Conditions for Which
Environmental Contaminants May Be a
Risk Factor
The indicators selected to answer this question represent
diseases and conditions that affect multiple systems of the
human body and are associated with a number of risk fac-
tors, some of \vhich include exposures to contaminants that
may be found in the air, water, and land. Some indicators
represent chronic conditions (e.g., various cancers, heart and
lung disease), some are primarily acute in nature (e.g., infec-
tious diseases), and others represent conditions of the devel-
oping fetus and neonate. Understandably, no striking trends
are evident across the broad categories of diseases represented
by the indicators. However, some changes in disease rates or
occurrence were observed for individual indicators. These
relate largely to disease patterns observed over time and to
differences observed across age groups, gender, and racial and
ethnic groups.
Generally, the occurrence of many chronic diseases in adults is
increasing with the aging of the population (Cancer indicator,
p. 5-43; Cardiovascular Disease indicator, p. 5-48; Chronic
Obstructive Pulmonary Disease indicator, p. 5-52). How-
ever, \vhile overall cancer incidence rates showed a steady
increase from the mid-1970s to the mid-1990s, rates have held
relatively steady between 1997 and 2004. With the excep-
tion of prostate cancer in males and breast cancer in females,
site-specific cancer rates also have remained fairly constant.
Similarly, prevalence rates for cardiovascular disease and
chronic obstructive pulmonary disease have shown no striking
changes between 1997 and 2006, -with the exception of an
overall increase in the prevalence of hypertension during this
time period. Prevalence rates for adult asthma have fluctuated
from 1997 to 2006, -with an overall increase during that time
period (Asthma indicator, p. 5-55).
5-68
EPA's 2008 Report on the Environment
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No distinct upward or downward patterns were revealed
between 1995 and 2005 for most of the acute infectious gas-
trointestinal diseases presented in this report. An exception
is the decrease in hepatitis A cases, which has been attributed
to childhood vaccination for this disease.57 Other observ-
able shifts in acute infectious diseases, such as an increase of
cryptosporidiosis in 2005, are difficult to interpret because
of acknowledged uncertainties in the completeness of dis-
ease reporting in a given year.58 Generally increased reported
occurrence of arthropod-borne diseases and legionellosis bears
•watching (Infectious Diseases indicator, p. 5-59).
Review of diseases in children and birth outcomes revealed
the following overall trends. Childhood cancer incidence has
increased slightly since 1975, with boys having a higher inci-
dence rate than girls. Leukemia and brain and other nervous
system cancers remain the leading cancer sites in children
(Childhood Cancer indicator, p. 5-46). Prevalence rates for
childhood asthma remain at historically high levels following
increases from 1980 through the late 1990s (Asthma indica-
tor, p. 5-55).59 A wide range of birth defects continues to be
reported each year, but with no notable shifts in prevalence
observed for specific types of defects from 1999 to 2004. Heart
malformations and other circulatory/respiratory anomalies
and musculoskeletal/integumental anomalies remain the most
prevalent types of birth defects based on birth certificate data
(Birth Defects indicator, p. 5-62). Among full-term single-
ton births, the percentage of low birthweight infants has not
varied from 1995 to 2004. Age of mother showed the greatest
influence, with the greatest number of low birthweight infants
born to younger mothers (less than 20 years old) (Low Birth-
weight indicator, p. 5-65). The highest rate of preterm births
is also seen in these younger mothers, though nearly compara-
ble and rising preterm birth rates are seen among mothers over
the age of 40 (Preterm Delivery indicator, p. 5-67).
Some differences were observed across racial and ethnic
groups. Observations are reported for the most recently avail-
able annual data set. Overall, cancer incidence is higher among
black males than for any other racial group. Less disparity was
observed between cancer incidence in white and black women.
With childhood cancers, higher rates have been consistently
reported in whites than in blacks (Cancer indicator, p. 5-43,
Childhood Cancer indicator, p. 5-46). For cardiovascular dis-
ease (p. 5-48), prevalence rates were generally reported highest
among whites and American Indians/Alaska Natives, followed
by blacks or African Americans and Asians. Asthma rates were
generally reported highest among blacks or African Americans
in children and American Indians/Alaska Natives in adults, fol-
io-wed by -whites and Asians (Asthma indicator, p. 5-55).
The percentage of preterm and low birth-weight infants is con-
sistently higher among blacks than whites (1.5 to nearly 3 times
higher). This observation is seen across all maternal age groups
57 Centers for Disease Control and Prevention. 2007. Summary of notifiable
diseases—United States, 2005. MMWR 54(53):9.
58 Ibid.
(Preterm Delivery indicator, p. 5-67; Low Birth-weight indica-
tor, p. 5-65). When available, reported disease rates -were gen-
erally lower (Asthma indicator, p. 5-55; Cardiovascular Disease
indicator, p. 5-48; Chronic Obstructive Pulmonary Disease
indicator, p. 5-52) or comparable (Preterm Delivery indicator,
p. 5-67; Low Birth-weight indicator, p. 5-65) in Hispanic versus
non-Hispanic populations.
Limitations, Gaps, and Challenges
In answering this question, EPA reviewed general trends in
morbidity and mortality of several diseases that may be related,
at least in part, to contaminants in the environment to -which
people may be exposed. The indicators presented in this section
provide an overall picture of specific disease rates or occurrence
across the nation, including among some population subgroups.
ROE indicator data sets, however, do not enable extensive
analysis of disease trends -within or across geographic regions,
nor do they allow fully consistent reporting of trends across
racial and ethnic groups. In addition, there are other diseases or
conditions of potential interest for -which no national scale data
are currently available, or for-which the strength of associations
•with environmental contaminants are still being evaluated. Spe-
cific limitations, data gaps, and challenges related to answering
the question on trends in disease are highlighted below.
Geographic Patterns
Mortality data sets enable some analysis at the EPA regional level,
but underlying data for most ROE indicators selected to answer
this question do not currently enable meaningful analysis of geo-
graphic trends across the nation. The regional analyses presented
in this report for cardiovascular disease and chronic obstructive
pulmonary disease mortality reveal no discernable patterns.
Other Diseases and Conditions for Which Environmental
Contaminants May Be Risk Factors
Additional data are needed to prompt or enable EPA to track
other diseases and conditions -with potential environmental
risk factors (direct or indirect), particularly those for -which
unexplained increases are being noted. Examples of diseases or
conditions -with suggestive or growing evidence that envi-
ronmental contaminants are a risk factor follow. The extent
to -which national-level indicators meeting ROE criteria are
available to track these diseases and conditions varies.
Behavioral and neurodevelopmental disorders in children
continue to receive attention. These include disabilities of the
functioning brain that affect a child's behavior, motor skills,
memory, or ability to learn. Examples include attention-deficit/
hyperactivity disorder (ADHD), dyslexia and other learning
disabilities, cerebral palsy, mental retardation, and autism.
Considerable evidence exists that lead and methylmercury
are associated -with mental retardation and impairment of
mental function and attention.60 While the role of other
59 Akinbami, L.J. 2006.The state of childhood asthma, United States, 1980-2005.
Advance data from vital and health statistics. Number 381. Hyattsville, MD:
National Center for Health Statistics,
60 Mendola, P., S.G. Selevan, S. Gutter, and D. Rice. 2002. Environmental factors
associated with a spectrum of neurodevelopmental deficits. Ment. Retard.
Dev. Disabil. Res. Rev. 8(3):188-197.
EPA's 2008 Report on the Environment
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environmental contaminants in contributing to some of these
disorders is not fully known or understood (e.g., for ADHD),
the \veight of evidence suggesting relationships between
behavioral and neurodevelopmental effects from exposure
to polychlorinated biphenyls (PCBs), environmental tobacco
smoke, and other contaminants continues to grow.61'62 The
National Health Interview Survey (NHIS) tracks ADHD and
mental retardation, though the accurate reporting of these
types of disorders is complicated by difficulties in diagnoses
and possible underreporting (e.g., institutionalized children
are excluded from the NHIS survey population).
As the U.S. population continues to age, more individuals are
afflicted with neurodegenerative disorders such as Parkinson's
disease and Alzheimer's disease. For example, Alzheimer's
disease is the seventh leading cause of death in the nation
(General Mortality indicator, p. 5-33). Such diseases are
characterized by the progressive loss of neural cells, which
lead to central nervous system dysfunction (e.g., memory loss,
cognitive deficits, personality changes, motor control abnor-
malities). The etiology of these disorders is multifactorial, but
in many cases the etiology is unknown. Ongoing research
is exploring the role, if any, of environmental contaminant
exposure (e.g., heavy metals, pesticides). Thus far, findings are
largely inconclusive due to conflicting results.63
Diabetes was reported as the sixth leading cause of death in
the U.S. in 2004 (General Mortality indicator, p. 5-33). Two
types of diabetes exist. Diabetes mellitus (type 2), the most
common form, is characterized by the body's resistance to
insulin action and a relative deficiency of insulin. Known risk
factors for diabetes mellitus include factors such as age, obe-
sity, family history, physical inactivity, and dietary glycemic
load. Type 1 diabetes results from decreased insulin produc-
tion by the pancreas as part of an autoimmune response. Onset
typically occurs before adulthood and believed to be triggered
by genetic predisposition and possible environmental factors.
Diabetes itself is a risk factor for the development of many
other acute and chronic conditions. Epidemiological research
has been conducted to evaluate possible associations between
environmental contaminant exposure and diabetes; however,
findings are inconclusive. Occupational and environmental
exposures to contaminants such as arsenic, PCBs, dioxins,
and nitrates have been examined.64'65 Other endocrine and
metabolic disorders, such as thyroid disorders, continue to be
studied. Research continues to evaluate the extent to which
various environmental contaminants are capable of disrupting
endocrine function in humans (e.g., phthalates, persistent
organic pollutants).
Reproductive function is another condition of interest to EPA.
Scientists are studying whether environmental contaminants
may cause alterations in reproductive function and contribute
to conditions such as ovarian failure, decreased sperm counts,
infertility, sub-fecundity, and possibly early onset of puberty.
For example, components of cigarette smoke and other
environmental contaminants have been studied in association
•with possible effects on female reproductive function.66 Other
contaminants under study include pesticides, dioxins, various
metals, and solvents.
Renal disease is of interest because of the vital function of
the kidneys in maintaining human health and the range of
complex factors that lead to kidney dysfunction and disease.
The kidneys can be seriously affected by a number of primary
diseases such as hypertension and diabetes. Nephritis and
nephritic syndrome were reported as the ninth leading cause
of death in 2004 (General Mortality indicator, p. 5-33). EPA
is interested because the kidney is known to be the target of
some environmental contaminants. For example, as evi-
denced through occupational exposure, poisoning, and other
experimental studies, exposure to heavy metals such as lead,
cadmium, and mercury has been shown to be nephrotoxic.67'68
The U.S. Renal Data System is a national data system that
collects, analyzes, and distributes morbidity and mortality
information about end-stage renal disease in the U.S.
Infectious diseases represent a continuing threat in the U.S.
and worldwide. CDC continues to monitor infectious diseases
and implement preventive strategies for infectious diseases
•whose incidence has increased within the past two decades or
threatens to increase in the near future.69 Infectious diseases
of EPA interest may shift over time, making tracking of these
diseases more of a challenge. An area of research interest for
arthropod-borne diseases, and a potential issue for zoonotic
diseases, is whether their incidence may change with changes
in environmental condition such as land use, local weather
conditions, or other environmental disturbances.
Other Data Collection Systems
To better answer the question, expanded national-level health
data collection systems are needed, as well as integration of
systems that collect health data. For example, the birth cer-
tificate data currently used to track birth defects on a national
level have limitations (see Birth Defects indicator, p. 5-62).
61 Schantz, S.L.,J.J.Widholm, and D.C. Rice. 2003. Effects of PCB exposure on
neuropsychological function in children. Review. Environ. Health Perspect.
111(3) :357-376.
62 State of California. 2005. Proposed identification of environmental tobacco
smoke as a toxic air contaminant. Part B: Health effects assessment for
environmental tobacco smoke. As approved by the Scientific Review Panel
on June 24, 2005. California Environmental Protection Agency, Office of
Environmental Health Hazard Assessment,
63 Brown, R.C., A.H. Lockwood, and B.R. Sonawane. 2005. Neurodegenera-
tive disorders: An overview of environmental risk factors. Environ. Health
Perspect. 113(9):1250-1256.
64 Longnecker, M.P, and J.L. Daniels. 2001. Environmental contaminants as
etiologic factors for diabetes. Environ. Health Perspect. 109(Suppl 6):871-876.
65 Remillard, R.B., and N.J. Bunce. 2002. Linking dioxins to diabetes: Epi-
demiology and biologic plausibility. Review. Environ. Health Perspect.
110(9):853-858.
66 Mlynarcikova, A., M. Fickova, and S. Scsukova. 2005. Ovarian intrafollicular
processes as a target for cigarette smoke components and selected environ-
mental reproductive disrupters. Review. Endocr. Regul. 39(l):21-32.
67 Klaassen, C.D., ed. 2001. Casarett and Doull's toxicology:The basic science of
poisons. Sixth edition. New York, NY: McGraw-Hill.
68 Jarup, L. 2003. Hazards of heavy metal contamination. Review. Br. Med. Bull.
68:167-182.
69 Centers for Disease Control and Prevention. 1998. Preventing emerging dis-
eases.A strategy for the 21st century. Atlanta, GA: U.S. Department of Health
and Human Services.
5-70
EPA's 2008 Report on the Environment
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CDC recognizes the need for continuing efforts to improve
birth defects surveillance, and recently released improved
national prevalence estimates for major birth defects looking at
data reported through the National Birth Defects Prevention
Network.70 Also, as noted above, systems do not exist at the
state or national level to track many of the diseases or condi-
tions that may be related to environmental hazards. Existing
environmental hazard, exposure, and disease tracking systems
are not linked together.
Some efforts are underway to begin tracking exposure and
health outcomes together. For example, CDC's "environmen-
tal public health tracking net-work" involves the collection
and integration of data from environmental hazard monitor-
ing and from human exposure and health outcome surveil-
lance; CDC's goal is to build a national tracking net-work
(http://www.cdc.gov/nceh/tracking/). In addition, CDC has
initiated the "environmental public health indicator project,"
•which identifies indicators of environmental hazards and
health effects that state health departments can use to develop
comprehensive environmental public health programs
(http://www.cdc.gov/nceh/indicators/default.htm). Such
programs will help bridge some existing gaps in knowl-
edge between disease trends and environmental condition.
These efforts also will enhance data collection efforts at the
community level (state and local) and help ensure better tem-
poral and spatial congruence between environmental, surveil-
lance, and biomonitoring programs.
Lastly, data collection systems that collect data at different
scales are available that may support future trend analysis.
For example, CDC and the National Cancer Institute (NCI)
have been combining forces to build a database of U.S. cancer
statistics with data from CDC's National Program of Cancer
Registries and NCI's Surveillance, Epidemiology, and End
Results Program (http://apps.nccd.cdc.gov/uscs/). Cancer
incidence data are available for 47 states, including six met-
ropolitan areas, and the District of Columbia, and represent
approximately 96 percent of the U.S. population.71 Another
example is asthma estimate data from CDC's state-based
Behavioral Risk Factor Surveillance System.
Centers for Disease Control and Prevention. 2006. Improved national
prevalence estimates for 18 selected major birth defects—United States,
1999-2001. MMWR54(51&52):1301-1305.
71 Centers for Disease Control and Prevention and National Cancer Institute.
2006. United States cancer statistics: 2003 incidence and mortality. US. Can-
cer Statistics Working Group,
EPA's 2008 Report on the Environment
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Chapter 6
Ecological
Condton
-------
Contents
6.1 Introduction 6-3
6.1.1 The Ecological Condition Paradigm 6-4
6.1.2 Overview of the Data 6-5
6.1.3 Organization of This Chapter 6-5
6.2 What Are the Trends in the Extent and Distribution of the Nation's Ecological Systems?. .6-7
6.2.1 Introduction 6-7
6.2.2 ROE Indicators 6-8
6.2.3 Discussion 6-16
6.3 What Are the Trends in the Diversity and Biological Balance
of the Nation's Ecological Systems? 6-18
6.3.1 Introduction 6-18
6.3.2 ROE Indicators 6-19
6.3.3 Discussion 6-25
6.4 What Are the Trends in the Ecological Processes That Sustain
the Nation's Ecological Systems? 6-27
6.4.1 Introduction 6-27
6.4.2 ROE Indicators 6-28
6.4.3 Discussion 6-30
6.5 What Are the Trends in the Critical Physical and Chemical Attributes
of the Nation's Ecological Systems? 6-31
6.5.1 Introduction 6-31
6.5.2 ROE Indicators 6-32
6.5.3 Discussion 6-42
6.6 What Are the Trends in Biomarkers of Exposure to Common Environmental
Contaminants in Plants and Animals? 6-45
6.6.1 Introduction 6-45
6.6.2 ROE Indicators 6-45
6.6.3 Discussion . . .6-46
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6.1 Introduction
The term "ecological condition" refers to the state of the
physical, chemical, and biological characteristics of the
environment, and the processes and interactions that con-
nect them. Understanding ecological condition is crucial, because
humans depend on healthy ecological systems for food, fiber,
flood control, and other benefits,1 and many Americans attribute
deep significance and important intangible benefits to ecological
systems and their diverse flora and fauna.2 As noted in the intro-
duction to this report, this chapter focuses on critical ecosystem
characteristics that are affected simultaneously by stressors in
multiple media, rather than those whose trends can be definitively
shown to be the results of trends in particular air, water, or land
stressors. The ability to report on ecological condition remains
significantly limited by the lack of indicators, but this chapter at
least provides a framework for examining ecological condition.
EPA's mission, broadly stated, is "to protect human health and
to safeguard the natural environment—air, water, and land—
upon which life depends."3 The translation of the mission into
programs, initiatives, and research efforts continues to evolve
\vithin the Agency and is reflected in program goals, regulatory
programs, and collaborative and educational efforts. EPA, other
federal agencies, and state agencies collectively bear responsibil-
ity for ensuring the protection of ecological systems, including
forests, public lands, oceans and estuaries, and particular species
or groups of species. Trends in ecological condition provide
insight into the degree to which the natural environment is
being protected.
In this chapter, EPA seeks to assess trends in critical attributes
of ecological condition on a national scale, using indicators to
address five fundamental questions:
• What are the trends in the extent and distribution of
the nation's ecological systems? This question exam-
ines trends in the overall extent (e.g., area and location) of
different kinds of ecological systems (e.g. forests, undevel-
oped lands, and -watersheds) and of spatial patterns in the
distribution of ecological systems that affect interactions of
nutrients, energy, and organisms.
• What are the trends in the diversity and biological
balance of the nation's ecological systems? This ques-
tion explores trends in the types and numbers of species that
live \vithin ecological systems. The question also examines
biological balance in terms of the proportional distributions
of species and the influence of interactions among native
and invasive species on the stability of ecological systems.
• What are the trends in the ecological processes that
sustain the nation's ecological systems? This question
EPA's 2008 Report on the Environment (ROE): Essentials
ROE Approach
This 2008 Report on the Environment:
• Asks questions that EPA considers
important to its mission to protect
human health and the environment.
• Answers these questions, to the extent
possible, with available indicators.
• Discusses critical indicator gaps, limita-
tions, and challenges that prevent the
questions from being fully answered.
ROE Questions
The air, water, and land chapters (Chapters
2, 3, and 4) ask questions about trends in
the condition and/or extent of the envi-
ronmental medium; trends in stressors to
the medium; and resulting trends in the
effects of the contaminants in that medium
on human exposure, human health, and
the condition of ecological systems.
The human exposure and health and
ecological condition chapters (Chapters
5 and 6) ask questions about trends in
aspects of health and the environment
that are influenced by many stressors
acting through multiple media and by
factors outside EPA's mission.
ROE Indicators
An indicator is derived from actual mea-
surements of a pressure, state or ambient
condition, exposure, or human health or
ecological condition over a specified geo-
graphic domain. This excludes indicators
such as administrative, socioeconomic, and
efficiency indicators.
Indicators based on one-time studies are
included only if they were designed to serve
as baselines for future trend monitoring.
All ROE indicators passed an independent
peer review against six criteria to ensure
that they are useful; objective; transparent;
and based on data that are high-quality,
comparable, and representative across space
and time.
Most ROE indicators are reported at the
national level. Some national indicators
also report trends by region. EPA Regions
were used, where possible, for consistency
and because they play an important role in
how EPA implements its environmental
protection efforts.
Several other ROE indicators describe
trends in particular regions as examples of
how regional indicators might be included
in future versions of the ROE. They are
not intended to be representative of trends
in other regions or the entire nation.
EPA will periodically update and revise
the ROE indicators and add new indicators
as supporting data become available. In the
future, indicators will include information
about the statistical confidence of status
and trends. Updates will be posted elec-
tronically at http://www.epa.gov/roe.
Additional Information
You can find additional information about
the indicators, including the underlying
data, metadata, references, and peer review
at http://www.epa.gov/roe.
Daily, G.C., ed. 1997. Nature's services: Societal dependence on natural eco-
systems.Washington, DC: Island Press.
Norton, B. 1988. Commodity, amenity, and morality: The limits of quantifica-
tion in valuing biodiversity. In: Wilson, E.O., ed. Biodiversity. Washington, DC:
National Academies Press, p. 521.
U.S. EPA. 2007. About EPA.
EPA's 2008 Report on the Environment
6-3
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focuses on trends in the critical processes that sustain eco-
logical systems, such as primary and secondary productivity,
nutrient cycling, decomposition, and reproduction.
• What are the trends in the critical physical and
chemical attributes of the nation's ecological sys-
tems? This question addresses trends in the physical and
chemical attributes of ecological systems. Physical attributes
can include climatological patterns, hydrology, and elec-
tromagnetic radiation, as well as major physical events that
reshape ecological systems, such as fires, floods, and •wind-
storms. This question also examines chemical attributes such
as pH, oxidation-reduction potential, and nutrient levels.
• What are the trends in biomarkers of exposure to
common environmental contaminants in plants and
animals? This question examines trends in biomarkers of
exposure to contaminants that are particularly important to
the health of plants and animals as well as to humans who
consume such organisms.
These ROE questions are posed without regard to whether
indicators are available to answer them. This chapter presents
the indicators available to answer these questions, and also
points out important gaps where nationally representative data
are lacking.
While the indicators of ecological condition (and those in the
previous chapter, "Human Exposure and Health") may be
directly influenced by pollutants, other environmental stres-
sors, and complex interactions among these factors, the indica-
tors are not intended to confirm direct causal relationships.
6.1.1 The Ecological
Condition Paradigm
Because ecological systems are dynamic assemblages of organ-
isms that have more or less continuously adapted to a variety
of natural stressors over shorter (e.g., fire, windstorms) and
longer (e.g., climate variations) periods of time, measuring
ecological condition is a complicated endeavor. It is not as
straightforward as monitoring water or air for temperature or
concentrations of pollutants. The complexity of interactions
\vithin ecological systems makes determination of the condi-
tion of a natural system difficult.4 In addition, people have
altered natural ecological systems to increase the productivity
of food, timber, fish, and game and to provide the infrastruc-
ture needed to support a modern society. How should the
ecological condition of these altered ecological systems be
measured and against what reference points?
Ecological systems are not necessarily naturally occurring
entities with well-defined, mutually exclusive boundaries;
rather, they are constructs with boundaries determined for
human scientific or management purposes. Consequently
there are many ways to define ecological systems, including
Ehrenfeld, D.H. 1992. Ecosystem health and ecological theories. In: Costanza.
R., E.G. Norton, and B.D. Haskell, eds. Ecosystem health: New goals for
environmental management.Washington, DC: Island Press, pp. 135-143.
National Research Council. 2000. Ecological indicators for the nation. Wash-
ington, DC: National Academies Press,
by the predominant biota, spatial scales, and physical charac-
teristics. These factors further complicate the definition and
measurement of ecological condition. Several recent reports
by experts in the field have provided guidance for current and
future efforts, however.
The National Research Council (NRC) report Ecological Indi-
cators for the Nation5 provides an introduction to recent national
efforts to measure ecological condition and a thoughtful dis-
cussion of the rationale for choosing indicators. EPA's Science
Advisory Board (SAB) also proposed a Framework for Assessing
and Reporting on Ecological Condition.6 The frame-work identi-
fied six essential attributes of ecological systems: landscape
condition, biotic condition, chemical and physical character-
istics, ecological processes, hydrology and geomorphology,
and natural disturbance regimes. The SAB report is organized
around questions about trends in each of these attributes, con-
solidating the last three into a single attribute. Neither report
identifies specific methodologies, net-work designs, or actual
datasets. The SAB and NRC documents provide the founda-
tion for the questions that are addressed -within this chapter.
Exhibit 6-1 is a conceptual depiction of the events that link
environmental changes and ecological outcomes in this para-
digm. "Stressors," indicated by thick arrows, represent factors
such as insect outbreaks or contaminants affecting the system.
These stressors act directly on one or more of the "essential
ecological attributes" shown in the circles in the center of the
diagram. Most of these attributes can, in turn, act on and be
acted on by others. The web of arrows among the indicators
Exhibit 6-1. Ecological condition paradigm
Stressors (shown as ) affect ecological attributes directly and
also indirectly through feedback (interaction) among the
attributes (e.g.,f).
U.S. Environmental Protection Agency. 2002. A framework for assessing and
reporting on ecological condition:An SAB report. EPA/SAB/EPEC-02/009.
6-4
EPA's 2008 Report on the Environment
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illustrates some of the possible interactions. Effects on ecologi-
cal attributes can be direct or indirect. The diagram illustrates
the fact that changes in ecological structure and processes
provide important feedback on the chemical and physical
structure of the environment in which these changes occur.
The overall changes in the attributes result in altered structure
and function of ecological systems, which in turn lead to out-
comes (positive or negative) about which society is concerned.
There have been other notable efforts conducted by EPA and
other federal agencies and institutions to describe the eco-
logical condition of the nation, either in total or by type of
ecological systems. These efforts include both indicator-based
and integrative approaches. The indicator-based approaches,
such as this report, use indicators to assess ecological condi-
tion. The integrated assessments do not rely on indicators;
rather, they comprehensively assess a wide range of data in
order to arrive at an overall picture of the status and trends in
ecological systems. Indicator approaches offer the advantage of
drawing attention to important trends and do not require an
extensive background in ecology, but are not able to capture
the complex interactions that characterize ecological systems.
6.1.2 Overview of the Data
This chapter, like the others in this report, is not intended to
be an exhaustive treatment of the condition of all ecologi-
cal systems in the nation. Rather, it provides a snapshot of
status or trends using the few ecological condition indicators
that are available at the national level and that meet the ROE
indicator criteria. Because ecological condition depends criti-
cally on the physical and chemical characteristics of land, air,
and water, this chapter draws on indicators from Chapters 2
through 4 of this report. Those chapters should be consulted
for the data sources of those indicators. Many of the indicators
continue to be drawn from The H. John Heinz III Center for
Science, Economics, and the Environment report The State of
the Nation's Ecosystems: Measuring the Lands, Waters, and Living
Resources of the United States.
Most of the data relied upon come from surveillance and
monitoring surveys. The key data sources for this chapter
reflect the fact that monitoring ecological condition is a multi-
organizational task. Organizations in addition to EPA that are
responsible for collecting the data to support indicators in this
chapter include the U.S. Department of Commerce (National
Oceanic and Atmospheric Administration), National Aeronau-
tics and Space Administration, U.S. Department of Agricul-
ture (Forest Service, Agricultural Research Service, National
Agricultural Statistics Service, and Natural Resource Conser-
vation Service), U.S. Department of Interior (U.S. Geological
Survey and U.S. Fish and Wildlife Service), and NatureServe
(a private research organization).
Programs such as the U.S. Department of Agriculture Forest
Inventory and Analysis program and the Natural Resources
Inventory have a long history because they measure aspects
of the environment that are critical to multi-billion-dollar
industries (e.g., timber, crops). Programs with a strictly "ecolog-
ical" focus (e.g., the U.S. Geological Survey's National Water
Quality Assessment Program [NAWQA], the multi-agency
Multi-Resolution Land Characteristics [MRLC] Consortium,
and EPA's Environmental Monitoring and Assessment Program
[EMAP]) are more recent, but equally informative.
The major challenges involve adequate coverage of the diverse
aspects of ecological condition. For example, there are numer-
ous groups of animals and plants, but there are ROE indicators
for only some of these. Major groups known to be undergoing
changes, such as amphibians, are not captured by the ROE
indicators. These challenges and limitations are described in
each of the subsections.
This chapter presents only data that meet the ROE indicator
definition and criteria (see Box 1-1, p. 1-3). Note that non-
scientific indicators, such as administrative and economic
indicators, are not included in this definition. Thorough doc-
umentation of the indicator data sources and metadata can be
found online at http://www.epa.gov/roe. All indicators were
peer-reviewed during an independent peer review process
(again, see http://www.epa.gov/roe for more information).
Readers should not infer that the indicators included reflect
the complete state of knowledge on current indicators of U.S.
ecological condition. Many other data sources, publications,
and site-specific research projects have contributed to the cur-
rent understanding of status and trends in indicators of U.S.
ecological condition, but are not used in this report because
they do not meet some aspect of the ROE indicator criteria.
6.1.3 Organization of
This Chapter
The remainder of this chapter is organized into five sections,
corresponding to the five questions EPA is seeking to answer
regarding trends in ecological condition. Each section intro-
duces the question and its importance, presents the National
Indicators selected to help answer the question, and discusses
•what the indicators, taken together, say about the question.
Some of the National Indicators presented are broken down
by EPA Regions or other appropriate regions. In addition,
several Regional Indicators are presented that capture regional
trends of particular interest to EPA Regions. These Regional
Indicators serve as models that could potentially be expanded
to other EPA Regions in the future. A map showing the EPA
Regions (and states within each Region) is provided in Chap-
ter 1 (Exhibit 1-1). Each section concludes by highlighting the
major challenges to answering the question and identifying
important information gaps.
Table 6-1 lists the indicators used to answer the five questions
in this chapter and shows the locations where the indicators
are presented.
EPA's 2008 Report on the Environment
6-5
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Table 6-1. Ecological Condition—ROE Questions and Indicators
Question
What are the trends in the extent and
distribution of the nation's ecological
systems?
What are the trends in the diversity
and biological balance of the nation's
ecological systems?
What are the trends in the ecological
processes that sustain the nation's
ecological systems?
What are the trends in the critical
physical and chemical attributes of
the nation's ecological systems?
What are the trends in biomarkers of
exposure to common environmental
contaminants in plants and animals?
Indicator Name
Land Cover (N/R)
Forest Extent and Type (N/R)
Forest Fragmentation (N/R)
Wetland Extent, Change, and Sources of Change (N)
Land Use (N)
Urbanization and Population Change (N)
Land Cover in the Puget Sound/Georgia Basin (R)
Ecological Connectivity in EPA Region 4 (R)
Relative Ecological Condition of Undeveloped Land in EPA
Region 5 (R)
Coastal Benthic Communities (N/R)
Benthic Macroinvertebrates in Wadeable Streams (N)
Bird Populations (N)
Fish Faunal Intactness (N)
Submerged Aquatic Vegetation in the Chesapeake Bay (R)
Non-Indigenous Benthic Species in the Estuaries of the
Pacific Northwest (R)
Carbon Storage in Forests (N)
U.S. and Global Mean Temperature and Precipitation (N)
Sea Surface Temperature (N)
Streambed Stability in Wadeable Streams (N)
High and Low Stream Flows (N)
Sea Level (N)
Nitrogen and Phosphorus Loads in Large Rivers (N)
Nitrogen and Phosphorus in Wadeable Streams (N)
Nitrogen and Phosphorus in Streams in Agricultural
Watersheds (N)
Lake and Stream Acidity (N)
Hypoxia in the Gulf of Mexico and Long Island Sound (R)
Coastal Fish Tissue Contaminants (N/R)
Contaminants in Lake Fish Tissue (N)
Ozone Injury to Forest Plants (N)
Section Page
4.2.2
6.2.2
6.2.2
3.4.2
4.3.2
4.3.2
4.2.2
6.2.2
6.2.2
3.5.2
3.2.2
6.3.2
6.3.2
3.5.2
6.3.2
6.4.2
6.5.2
6.5.2
3.2.2
3.2.2
6.5.2
3.2.2
3.2.2
3.2.2
2.2.2
3.5.2
3.8.2
3.8.2
2.2.2
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6-8
6-11
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4-14
4-19
4-10
6-13
6-14
3-44
3-21
6-20
6-21
3-46
6-23
6-28
6-32
6-37
3-11
3-8
6-39
3-17
3-13
3-15
2-42
3-48
3-61
3-63
2-24
N = National Indicator
R = Regional Indicator
N/R = National Indicator displayed at EPA Regional scale
6-6
EPA's 2008 Report on the Environment
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6.2 What Are the
Trends in the Extent
and Distribution of the
Nation's Ecological
Systems?
6.2.1 Introduction
Ecological systems,7 ranging from forests and -watersheds to
•wetlands and coral reefs, are the foundation of the environment.
An ecological system can be defined as a spatially explicit unit
of the Earth that includes all of the organisms, along with all
components of the abiotic environment, within its boundaries.
Ecological systems are not isolated but blend into and interact
•with other systems. The spatial coverage and arrangement of
ecological systems influence the types of animals and plants
that are present; the physical, chemical, and biological processes
in the system; and the resiliency of the systems to perturba-
tions.8 Ecological systems influence water and nutrient cycles,
the building of soils, the production of oxygen, sequestration of
carbon, and many other functions important for the health of
the planet and people who depend on them.
This section examines trends in the extent and distribution
of ecological systems. Extent refers to the physical coverage
of an ecological system; it can be reflected as area or percent
compared to a baseline or total area. Distribution includes the
pattern or arrangement of the components of an ecological
system and is dependent on the scale of analysis. For example,
the national distribution of forests can be estimated by a per-
cent coverage, but within a stand of trees the distribution may
involve patterns of gaps, species, and edge/interior ratios. As
noted in Section 6.1.1, ecological systems can be defined by
predominant biota, spatial scales, and physical characteristics.
Extent indicators typically are based on physical and biologi-
cal characteristics that are observable by remote sensing, with
indistinct boundaries operationally defined according to some
scientific or resource management construct.9
As noted in Chapter 1, safeguarding the natural environment
is an integral part of EPA's mission. EPA traditionally has been
most concerned with maintaining the quality of air, water, and
land necessary to support balanced biological communities and
the processes that support them; however, the success of these
Likens, G. 1992. An ecosystem approach: Its use and abuse. Excellence in
ecology, book 3. Oldendorf/Luhe, Germany: Ecology Institute.
Wilson, E.O. 1992.The diversity of life. Cambridge, MA: Belknap Press.
The H.John Heinz III Center for Science, Economics, and the Environment.
2005.The state of the nation's ecosystems: Measuring the lands, waters, and
living resources of the United States. New York, NY: Cambridge University
Press.Web update 2005.
Peterson, D.L., andVT. Parker. 1998. Ecological scale:Theory and applica-
tions. New York: Columbia University Press.
efforts requires that ecological systems not be altogether lost or
fragmented. The potential influences of pollutants on the extent
and distribution of ecological systems are a prime concern, and,
in turn, the extent and distribution of ecological systems have
far-reaching influences on air and water quality.
Apparent trends in extent and distribution of ecological systems
depend on the temporal and spatial scale of assessment. For this
reason, both National and Regional Indicators are particularly
valuable. Temporal changes occur naturally over long time scales,
such as those associated with geological and climatological
forces (e.g., glaciation). Change can also occur more quickly as
a result of direct shifts in land use (e.g., forest to development
and historical filling of wetlands), alterations of nutrient and
hydrological cycles (e.g., dam removal), introduction of invasive
species (e.g., Asian carp), pollutant exposure (e.g., acid rain), or
extreme weather events, which all act over comparatively short
time periods. Thus, trends can be the result of natural forces or
may be accelerated by human activity.
The spatial scale of alterations also represents a significant fac-
tor in tracking ecological condition. Alterations that are short
in duration and local in nature (e.g., seasonal droughts or a
•windfall in a closed forest canopy) may not have large-scale
or lasting effects on ecological systems. Alterations that are
chronic in nature and occur over large areas may affect entire
ecosystems over long periods of time, especially if they affect
soil formation, microclimate, refugia for recolonizing species,
etc. Particularly relevant discussions of the importance of scale
in ecological processes, monitoring, and management can be
found in a number of relatively recent publications.w-11-12
Different regions and different ecological systems respond to
stressors in different ways, resulting in unique regional distribu-
tions of species and habitats. The result is that across any slice of
landscape the extent and distribution of ecological systems may
shift.13 In the case of habitat loss, large impacts may occur and
the extent of coverage may be reduced or eliminated altogether.
More subtle changes in ecological systems can occur that are
not captured in simple metrics of extent and distribution. These
changes are discussed in later sections of this chapter.
Fragmentation, the division of previously uninterrupted
habitat, can have either negative or positive impacts on
communities.14 Examples of fragmentation include build-
ing high-ways through a forest, damming a river in a manner
that limits migration offish, or developing waterfronts in a
manner that splits apart bordering marshlands. Fragmentation
and the increasing area of edge habitat may force migrating
species to find new transport corridors, may allow new species
(e.g., competitors, pathogens, weeds) to enter areas previously
11 Niemi, G., and M. McDonald. 2004. Application of ecological indicators.
Annu. Rev. Ecol. Evol. Syst. 35:89-111.
12 Findlay C.S., and L. Zheng. 1997. Determining characteristic stressor scales
for ecosystem monitoring and assessment.}. Environ. Manage. 50(3):265-281.
13 The H.John Heinz III Center for Science, Economics, and the Environment.
2005. Forest pattern and fragmentation. In: The state of the nation's ecosys-
tems: Measuring the lands, waters, and living resources of the United States.
New York, NY: Cambridge University Press.Web update 2005.
14 Fahrig, L. 1997. Relative effects of habitat loss and fragmentation on popula-
tion extinction. J.Wildl. Manage. 61(3):603-610.
EPA's 2008 Report on the Environment
6-7
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blocked from immigration, and in some cases may actually
increase biodiversity.15 Regardless of the impact, fragmenta-
tion likely will result in shifting distributions of species.
Trends in ecological system extent and distribution are highly
dependent on the evaluation scale. At one scale, coastal -wet-
lands may appear to be uninterrupted and uniform. However,
at a more refined scale, edges, patches, corridors associated
•with tidal creeks, and discontinuous distributions of species
become evident. Defining systems in terms of local organiza-
tion or predominant species facilitates discussion and analysis,
but may also obscure the important linkages among systems
across landscapes. Therefore, while it is helpful to discuss
trends in the extent and distribution of systems such as -wet-
lands or forests, each system is tied into global water, nutrient,
carbon, and energy cycles.
The indicators discussed in this section fall into three broad
categories: indicators of the extent and distribution of forests,
indicators of the extent and distribution of wetlands, and indi-
cators of land use.
6.2.2 ROE Indicators
In this question, trends in the extent and distribution of eco-
logical systems are evaluated for a subset of systems including
forests, wetlands, undeveloped lands, and developed lands.
To answer the question on extent and distribution of eco-
logical systems, this report relies primarily on six National
Indicators and three Regional Indicators (Table 6-2). Data on
trends in extent and distribution of ecological systems come
from a variety of sources, including satellite remote sensing,
geographic information systems, and independent field stud-
ies. Information for the indicators discussed in this section is
drawn from several national assessments including the U.S.
Department of Agriculture (USDA) Forest Service Forest
Inventory and Analysis program, the U.S. Fish and Wildlife
Service's Wetlands Status and Trends Survey, the National
Land Cover Dataset/Database (NLCD) for 1992 and 2001,
and the USDA National Resources Inventory.
Table 6-2. ROE Indicators of Trends in Extent and Distribution
of the Nation's Ecological Systems
National Indicators Section
Land Cover (N/R)
Forest Extent and Type (N/R)
Forest Fragmentation (N/R)
Wetland Extent, Change, and Sources of Change
Land Use
Urbanization and Population Change
4.2.2
6.2.2
6.2.2
3.4.2
4.3.2
4.3.2
Regional Indicators Section
Land Cover in the Puget Sound/Georgia Basin
Ecological Connectivity in EPA Region 4
Relative Ecological Condition of Undeveloped Land in EPA Region 5
4.2.2
6.2.2
6.2.2
Page
4-7
6-8
6-11
3-32
4-14
4-19
Page
4-10
6-13
6-14
N/R = National Indicator displayed at EPA Regional scale
INDICATOR
Forest Extent and Type
The forests of the U.S. cover extensive lands in both the
eastern and -western thirds of the country. While the
amount of forest land has remained nearly unchanged since
the beginning of the 20th century, regional changes both in
amount and types of forest cover have occurred as a result
of changing patterns of agriculture and development. The
distribution of various forest cover types is a critical deter-
minant of the condition of forest ecosystems.
This indicator is based on data from the U.S. Depart-
ment of Agriculture (USDA) Forest Service Forest Inven-
tory and Analysis (FIA) program. The FIA program, using
a statistical survey design and comparable methods across
the U.S., collects various data that help assess the extent,
type, age, and health of the nation's forest land. Because
the surveys are repeated over time, the FIA data provide
an indication of trends in both the extent and composition
15 Fahrig, L. 2003. Effects of habitat fragmentation on biodiversity. Annu. Rev.
Ecol. Syst. 34:487-515.
6-8
EPA's 2008 Report on the Environment
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INDICATO
Forest Extent and Type (continued)
Exhibit 6-2. Changes in the extent of forest land in the U.S. by EPA Region, 1907-20023
A 1907-1938
1938-1953
C 1953-1977
D 1977-2002
Reporting period
Coverage: All 50 states.
Data source: Smith et al., 2001, 2004
Exhibit 6-3. Timberland area in the eastern U.S. by forest type, 1953-20023
140
120
100
80
60
40
20
0
140
120
100
80
60
40
20
0
White-red-jack pine Spruce-fir Longleaf-slash pine Loblolly-shortleaf pine I Oak-pine
Oak-hickory
Mi. . .
Lfi-
JlfMl
'53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02
Oak-gum-cypress Elm-ash-cottonwood Maple-beech-birch Aspen-birch Non-stocked
Jlliil
Jl
JIIW
I I I
'53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02
Year
Coverage: States in the eastern U.S., based on USDA Forest Service reporting regions (see map at right). These data cover timberland, as
defined by the Forest Service's Forest Inventory and Analysis (FIA) Program. Approximately 94% of the forest land in the eastern states
is timberland.
Data source: Smith etal., 2001, 2004
EPA's 2008 Report on the Environment 6-9
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w*
INDICATOR
Forest Extent and Type (continued)
Exhibit 6-4. Timberland area in the western U.S. by forest type, 1953-20023
'53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02
40
30
20
10
Lodgepole pine
Redwood
i i i i
Other western
softwood types
Western hardwood
types
Pinyon-juniper
Non-stocked
III
111
-r-r-r
'53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02 '53'63 77'87'97'02
Year
Coverage: States in the western U.S. (including Alaska and Hawaii), based on USDA Forest Service reporting
regions (see map at right). These data cover timberland, as defined by the Forest Service's Forest Inventory
and Analysis (FIA) Program. Approximately 39% of the forest land in the western states is timberland.
Data source: Smith etal., 2001, 2004
ft
West
&Ss& t jf
stef
PEast
of forest land. The extent data are collected for all forest
lands across the nation, but species composition data over
time are only available for timberland as defined by FIA data
collection procedures (that is, forests capable of producing
at least 20 cubic feet per acre per year of industrial wood
and not withdrawn from timber utilization by statute or
regulation). Timberland makes up 94 percent of the forest
land area in the eastern U.S. and 39 percent of forest land
in the western U.S. as of 2002 (Smith et al, 2004). Extent
data are collected for individual states, but have been sum-
marized by EPA Region for this indicator.
What the Data Show
After a slight increase in forest land nation-wide between
1907 and 1938, forest acreage decreased by more than 16
million acres between 1938 and 1977, before increasing
by 5.3 million acres over the past three decades (Exhibit
6-2). There are variations in trends in forest cover among
the different EPA Regions. For example, between 1907
and 2002, forest land declined by roughly 22 million acres
in Region 6 and more than 12 million acres in Region 9.
Over the same period, forest land increased by 13 million
acres in Region 3 and by 10 million acres in Region 5.
In addition to changes in the extent of forest, there have
been changes in the types of forests over time (Exhibits 6-3
and 6-4). The largest changes in the eastern U.S. over the
1953-2002 period occurred in the maple-beech-birch forest
type and the oak-hickory forest type, which gained 27.5
million acres and 23 million acres, respectively, since 1953.
In the West, the fir-spruce type and Western hard-wood
type also have increased (about 11.5 million acres each) since
1953, -while the hemlock-Sitka spruce, pinyon-juniper, and
ponderosa-Jeffrey pine forest types have decreased by about
13.6 million, 8.8 million, and 8.7 million acres respectively.
The Western white pine forest type has decreased by 5.3
million acres, or about 96 percent of its 1953 acreage.
Indicator Limitations
• Data on extent of forest land have an uncertainty of 3
to 10 percent per million acres for data reported since
1953. In 1998 Congress mandated that the FIA move
to annual inventories. While data now are collected
more often, fewer data are collected in any given year.
Because area estimates now are based on a smaller
sample size, the precision of the national estimates may
be reduced relative to pre-1998 dates.
• Most of the specific data related to species and age
classes are only collected on lands classified as timber-
land and not forest land in general.
6-10
EPA's 2008 Report on the Environment
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INDICATOI
Forest Extent and Type (continued)
• In addition to extent and species class, age class also influ-
ences the use of forest land as habitat by different species.
Younger and older stands of forest have increased over the
past half-decade, while middle-aged stands of more mer-
chantable timber have decreased (Smith et al., 2001, 2004).
Data Sources
This indicator is based on data from two USDA Forest
Service reports (Smith et al., 2001, 2004), which provide
current and historical data on forest extent and type by
state. Most data were obtained from the 2004 report; the
2001 report was consulted only for 1963 data, which were
excluded from the more recent report. Data were originally
collected by the USDA Forest Service's FIA program; origi-
nal survey data are available from the FIA database (USDA
Forest Service, 2005) (http://www.fia.fs.fed.us/tools-data/).
References
Smith, W.B., P.O. Miles, J.S. Vissage, and S.A. Pugh.
2004. Forest resources of the United States, 2002. General
Technical Report NC-241. St. Paul, MN: USDA Forest
Service, North Central Research Station.
Smith, W.B., J.S. Vissage, D.R. Darr, and R.M. Sheffield.
2001. Forest resources of the United States, 1997. General
Technical Report NC-219. St. Paul, MN: USDA Forest
Service, North Central Research Station.
USDA Forest Service. 2005. Forest Inventory and Analy-
sis, national FIA data base systems. Accessed 2005.
orest Fragmentatio
The amount of forest land in the U.S. monitored by the
U.S. Department of Agriculture (USDA) Forest Service
has remained nearly constant over the past century, but the
patterns of human land use have affected its distribution
from one region of the U.S. to another. Forest fragmen-
tation involves both the extent of forest and its spatial
pattern, and is the degree to which forested areas are being
broken into smaller patches and pierced or interspersed
•with non-forest cover.
Forest fragmentation is a critical aspect of the extent and
distribution of ecological systems. Many forest species are
adapted to either edge or interior habitats. Changes in the
degree or patterns of fragmentation can affect habitat qual-
ity for the majority of mammal, reptile, bird, and amphib-
ian species found in forest habitats (Fahrig, 2003). As forest
fragmentation increases beyond the fragmentation caused
by natural disturbances, edge effects become more domi-
nant, interior-adapted species are more likely to disappear,
and edge- and open-field species are likely to increase.
This indicator of forest fragmentation was developed by
the USDA Forest Service. The indicator is based on the
2001 National Land Cover Database (NLCD), which was
constructed from satellite imagery showing the land area of
the contiguous U.S. during different seasons (i.e., leaves-on
and leaves-off) around the year 2001 (Homer et al., 2007).
The USDA Forest Service's Southern Research Station
performed a re-analysis of the NLCD, aggregating the four
NLCD forest cover classes (coniferous, deciduous, mixed,
and wetland forest) into one forest class and the remaining
land cover classes into a single non-forest class (USDA For-
est Service, 2007). A model that classifies forest fragmenta-
tion based on the degree of forest land surrounding each
forest pixel (a square approximately 30 meters on each
edge) for various landscape sizes (known as "windows")
provides a synoptic assessment of forest fragmentation for
the contiguous U.S. by assessing each pixel's "forest neigh-
borhood" within various distances.
Results are based on four degrees of forest cover: "core"
if a subject pixel is surrounded by a completely forested
landscape (no fragmentation), "interior" if a subject pixel is
surrounded by a landscape that is 90 to 100 percent forest,
"connected" if a subject pixel is surrounded by a landscape
that is 60 to 90 percent forest, and "patchy" if the subject
pixel is surrounded by less than 60 percent forest. The
window (landscape) size used for this analysis was 13 by
13 pixels, 390 meters on each edge, or about 15.2 hectares
(37.6 acres). The window is shifted one pixel at a time over
the map, so the target population for the indicator is all
forested pixels in the contiguous U.S. Percent forest was
resampled from 30-meter pixel data and aggregated by
state to develop the EPA Region-specific breakouts.
What the Data Show
Slightly more than 26 percent of the forested pixels in the
U.S. represent "core" forest, i.e., landscapes dominated
by forest (Exhibit 6-5). However, the data for "interior"
and "core" forests suggest that fragmentation is extensive,
•with few large areas of complete, unperforated forest cover.
About 19 percent of forest pixels in the U.S. occur in a
landscape where less than 60 percent of the "neighbor-
hood" is forest (i.e., forest cover is "patchy").
There is considerable regional variation in forest fragmen-
tation (Exhibit 6-5). Regions 1, 2, and 3 have more than
30 percent "core" forest pixels, while fewer than 20 percent
of the forest pixels in Region 7 are "core" forest. From the
opposite perspective, fewer than 10 percent of forest pixels in
EPA's 2008 Report on the Environment
6-11
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w*
INDICATOR
Forest Fragmentation (continued)
Region 1 are surrounded by less than 60 percent forest, corn-
pared to almost 40 percent of the forest pixels in Region 7.
Indicator Limitations
• Trend information is not available for this indicator.
Although earlier land cover data are available as part of
the 1992 NLCD, they are not directly comparable with
the 2001 NLCD due to differences in classification
methodology. Efforts to compare these two products
are ongoing.
• The apparent degree of connectivity depends on the size
of the window. In a similar analysis of 1992 NLCD data,
Riitters (2003) determined that the percentages for all
categories (especially "core" and "connected" forest pix-
els) decrease rapidly as the size of the window is increased
progressively from 18 to 162, 1,459, and 13,132 acres.
• Because the non-forest land cover classes were aggre-
gated, this indicator does not distinguish between
natural and anthropogenic fragmentation (although such
a distinction has been made for global fragmentation by
Wade etal, 2003).
• The data do not include Hawaii or Alaska, which account
for about 1 out of every 6 acres of forest land in the U.S.
Data Sources
An earlier version of this analysis was published in Riitters
(2003) and Heinz Center (2005). The analysis presented
here has not yet been published; data were provided by the
USDA Forest Service (2007), and EPA grouped the results
by EPA Region. This indicator is based on land cover data
from the 2001 NLCD (MRLC Consortium, 2007).
References
Fahrig, L. 2003. Effects of habitat fragmentation on biodi-
versity. Annu. Rev. Ecol. Evol. Syst. 34:487-515.
Homer, C., J. Dewitz, J. Fry, M. Coan, N. Hossain, C.
Larson, N. Herold, A. McKerrow, J.N. VanDriel, andj.
Wickham. 2007. Completion of the 2001 National Land
Cover Database for the conterminous United States.
Photogramm. Eng. Rem. S. 73(4):337-341.
The H. John Heinz III Center for Science, Economics, and
the Environment. 2005. Forest pattern and fragmentation.
In: The state of the nation's ecosystems: Measuring the
lands, \vaters, and living resources of the United States. New
York, NY: Cambridge University Press. Web update 2005.
MRLC Consortium. 2007. National Land Cover Database
2001 (NLCD 2001). Accessed 2007.
Riitters, K.H. 2003. Report of the United States on the
criteria and indicators for the sustainable management of
temperate and boreal forests, criterion 1: Conservation of
Exhibit 6-5. Forest fragmentation in the contiguous
U.S. by EPA Region, based on 2001 NLCDab
Degree of forest cover:0
Core
Interior
Connected
Patchy
38.0
26.7
27.8
7.5
33.5
33.3
23.5
23.6
28.7
14.3
30.3
12.8
22.1
23.1
35.9
19.0
21.4
22.8
33.8
22.0
Percent of forested pixels in each category:
Region 1
Region 2
Region 3
Region 4
Region 5
Region 6
Region 7
Region 8
Region 9
Region 10
All U.S.
Coverage: Areas of the contiguous
48 states classified as "forested" by
the 2001 National Land Cover
Database (NLCD).
"Totals may not add to 100% due to
rounding.
=See text for definitions of forest
cover categories.
Data source: USDA Forest Service, 2007
23.0
15.6
21.0
15.4
32.3
31.0
23.7
38.0
27.8
22.8
29.2
20.2
29
7
22.5
29.4
18.4
29.4
26.0
31.9
12.8
26.1
22.9
32.1
18.9
EPA Regions
biological diversity, indicator 5: Fragmentation of forest
types. Final report. FS-766A. In: Darr, D., ed. Data report:
A supplement to the National Report on Sustainable Forests.
Washington, DC: USDA Forest Service.
USDA Forest Service. 2007. Data provided to EPA by Kurt
Riitters, USDA Forest Service. September 18, 2007.
Wade, T.G., K.H. Riitters, J.D. Wickham, and K.B. Jones.
2003. Distribution and causes of global forest fragmentation.
Conserv. Ecol. 7(2):7.
^
6-12
EPA's 2008 Report on the Environment
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Ecological Connectivity in EPA Region 4
Unprotected
52%
As part of their natural functioning,
ecological systems remove particulate
matter and carbon dioxide from the air,
purify surface and ground water, reduce
flooding, and maintain biological diversity.
These functions depend on a connected
ecological "frame-work" of high-quality
land consisting of central hubs intercon-
nected by corridors that provide for the
movement of energy, matter, and species
across the landscape. This frame-work of
connectivity is threatened by agricultural
and silvicultural practices, road develop-
ment, and "urban sprawl" that fragment
the landscape. Maintaining ecological con-
nectivity protects the entire system.
The Ecological Connectivity Indicator
(ECI) developed by EPA Region 4 (Dur-
brow et al., 2001) consists of a frame-work
that captures the connectivity of important
natural areas and ecological systems across
the landscape of the Region (Alabama,
Florida, Georgia, Kentucky, Mississippi,
North Carolina, South Carolina, and Ten-
nessee). Four ecological aspects contribute
to the functionality of the ECI infrastruc-
ture (see Carr et al., 2002, for additional
details). The most important of the four,
hub and corridor connectivity, forms the
basis for this indicator. Hub and corri-
dor connectivity shows the connections
among critical ecological systems in the
Region. Hubs are large areas of impor-
tant natural ecosystems such as the Okefenokee National
Wildlife Refuge in Georgia and the Osceola National
Forest in Florida. Connections, referred to as "corridors,"
are links to support the functionality of the hubs (e.g.,
the Pinhook Swamp -which connects the Okefenokee and
Osceola hubs). The ECI frame-work is based on land cover
data obtained from the 1992 National Land Cover Dataset
(NLCD), -which -was constructed from satellite imagery
(Landsat) showing the land area of the contiguous U.S.
during different seasons (i.e., leaves-on and leaves-off) dur-
ing the early 1990s. In many locations, the best available
Landsat images -were collected between 1991 and 1993,
•with data in a few locations ranging from 1986 to 1995.
What the Data Show
The hub and connection frame-work covers 43 percent of
the total land and -water resources in EPA Region 4—30
percent classified as hubs and 13 percent as corridors
(Exhibit 6-6). Currently, 22 percent of this frame-work
area is protected as conservation land, 12 percent is in
Exhibit 6-6. Ecological hubs and corridors in EPA Region 4,
based on 1992 NLCD
Surface area of Region 4
(land and water)
Not hubs
or corridors
57%
Protected status of hubs
and corridors
Existing
conservation
lands
22%
12%-
14%-
Data source: U.S. EPA, 2002
—Open waters in the public domain
(outside conservation lands)
-Wetlands
(outside conservation lands)
the public domain as open -water, and an additional 14
percent is classified as -wetlands, for a total of 48 percent
of hub and corridor acreage being afforded some type of
long-term protection.
Indicator Limitations
• Trend information is not available for this indicator. The
most important data layer used in the ECI development
is the NLCD from the early 1990s. Establishing trends
in the indicator may be limited by the availability of
comparable land cover/land use data in the future.
• Due to both the limited availability of data (ecologi-
cal data not available or not in digital or geographic
information system [GIS] format) and the Southeastern
Ecological Frame-work (SEF) parameter that sets a size
threshold of 5,000 acres for ecological hubs, the results
do not comprehensively include each and every ecologi-
cally important area in the Southeast. The appropriate
geographic scale of connectivity depends on the species
and communities that are the focus of particular protec-
tion efforts (Carr et al., 2002).
EPA's 2008 Report on the Environment
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INDICATOR
Ecological Connectivity in EPA Region 4 (continued)
Data Sources
The hub and corridor map was provided by EPA Region
4's SEF project, and is available as a GIS data layer from the
SEF Web site's data page (U.S. EPA, 2002) (http://geoplan.
ufl.edu/epa/data.html). The summary statistics shown in the
pie charts in Exhibit 6-6 are presented in Carr et al. (2002).
This analysis was based on the 1992 NLCD (USGS, 2005)
(http://landcover.usgs.gov/natllandcover.php) and several
additional datasets described in Carr et al. (2002); input data
layers can be obtained on CD by following instructions on
the SEF Web site (U.S. EPA, 2002).
References
Carr, M.H., T.D. Hoctor, C. Goodison, P.O. Zwick, J.
Green, P. Hernandez, C. McCain, J. Teisinger, and K.
Whitney. 2002. Final report: Southeastern Ecological
Frame-work. Region 4. Atlanta, GA: U.S. Environmental
Protection Agency.
Durbrow, B.R., N.B. Burns, J.R. Richardson, and CW.
Berish. 2001. Southeastern Ecological Frame-work: A plan-
ning tool for managing ecosystem integrity. In: Hatcher,
K.J., ed. Proceedings of the 2001 Georgia Water Resources
Conference. Athens, GA: University of Georgia.
U.S. EPA (United States Environmental Protection
Agency). 2002. The EPA Southeastern U.S. Ecological
Frame-work project.
USGS (United States Geological Survey). 2005. National
Land Cover Dataset 1992 (NLCD 1992). Accessed 2005.
INDICATOR
Relative Ecological Condition of Undeveloped Land in
EPA Region 5
Ecological condition in the ROE is approached using
questions broadly relating to landscape, biological
diversity, ecological function, and the physical and chemi-
cal makeup of the environment, but no attempt is made
at the national level to capture ecological condition in a
small number of indices. In this indicator, the ecological
condition of undeveloped land in EPA Region 5 (Illinois,
Indiana, Michigan, Minnesota, Ohio, and Wisconsin) is
characterized based on three indices derived from criteria
representing diversity, self-sustainability, and the rarity of
certain types of land cover, species, and higher taxa (White
and Maurice, 2004). In this context, "undeveloped land"
refers to all land use not classified as urban, industrial, resi-
dential, or agricultural.
Geographic units referred to as cells are used to quantify
geographic information. A spatially explicit model using
ecological theory and geographic information system (GIS)
technology -was used to create 20 data layers of 300-meter
by 300-meter cells. These layers originate from several
sources, including -water quality datasets, state Natural
Heritage Program databases (for species abundance), and
the 1992 National Land Cover Dataset (NLCD), which
•was constructed from satellite imagery (Landsat) show-
ing the land area of the contiguous U.S. during different
seasons (i.e., leaves-on and leaves-off) during the early
1990s. In many locations, the best available Landsat images
•were collected between 1991 and 1993, -with data in a few
locations ranging from 1986 to 1995. For this indicator,
data layers -were combined to generate three indices, -which
represent estimates of three criteria:
• Ecological diversity. The relative diversities of popu-
lations (species), communities, and ecological systems
in any given location on the landscape. Four data layers
•were used to derive this index.
• Ecological self-sustainability. The potential for an
ecological system to persist for years without external
management; it is negatively impacted by two factors:
landscape fragmentation and the presence of chemi-
cal, physical, and biological stressors. Twelve data layers
•were used to derive this index.
• Rarity. The rarity of land cover, species, and higher
taxa. Four data layers were used to derive this index.
The model produces composite layers that are statisti-
cally independent. The scores for each criterion are nor-
malized from 1 to 100 and each layer contributes equally
to the final index (all of the data layers are -weighted
equally). In all the data layers and the resultant criteria
layers, scores are normalized from 0 to 100. Zero always
indicates the lowest quality, the greatest stress, or the
least valuable observation, and 100 indicates the highest
quality, least stress, or most valuable observation. While
6-14
EPA's 2008 Report on the Environment
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Relative Ecological Condition of Undeveloped Land in
EPA Region 5 (continued)
Exhibit 6-7. Distribution of index scores for the
relative ecological condition of undeveloped
land in EPA Region 5, 1990-1992a
~M 150,000
100,000
50,000
A. Diversity index
2? 250,000
jf 200,000
o
£ 150,000
20 40 60
Index score
B. Sustainability index
100
-£ 600,000
400,000
200,000
20 40 60
Index score
C. Rarity index
20
40 60
Index score
100
Coverage: Undeveloped land in EPA Region 5, based on the
1992 National Land Cover Dataset (NLCD). For this analysis,
"undeveloped" land is any land that the NLCD classifies as bare
rock/sand/clay, deciduous forest, evergreen forest, mixed forest,
shrubland, grasslands/herbaceous, woody wetlands, emergent
herbaceous wetlands, or open water.
Data source: U.S. EPA, 2006
it has not been done for this indicator, the three compos-
ite scores can be summed to result in a final "ecological
condition" score for each cell (White and Maurice, 2004).
Cell counts (a measure of geographic coverage) are used
to indicate the distributions of scores associated with three
index scores of ecological condition of undeveloped land:
diversity, sustainability, and rarity.
What the Data Show
The frequency distributions of the 1992 baseline scores are
quantified and plotted for each criterion (Exhibit 6-7), and
these provide a baseline against which to track future land-
scape trends in diversity, sustainability, and rarity. Diversity
scores generally run from 20 to 80 across the region, signi-
fying that most areas are in the moderate diversity range.
More than 90 percent of the region has sustainability scores
above 50, but rarity scores above 50 are seldom encoun-
tered. The highest index scores are found largely in the
northern forests of Minnesota, Wisconsin, and Michigan
and along the large rivers in Ohio, Indiana, and Illinois
(Exhibit 6-8).
Indicator Limitations
• Trend information is not available for this indicator.
Establishing trends in the indicator may be limited by the
availability of comparable land cover/land use data in the
future.
• Although this indicator is designed to be comparable
across undeveloped land within Region 5, layers were
ranked within ecoregions for some of the components in
order to account for different geophysical, geochemical,
or climatic features of each ecoregion.
• Aquatic systems and connectivity resulting from water
flow paths are not adequately covered and small, but
potentially keystone, systems are not a part of the analy-
sis (U.S. EPA, 2005).
• The data layers that contribute to each index were
•weighted equally, which may not reflect the actual rela-
tive importance of each layer (U.S. EPA, 2005).
• The resolution and uncertainty of the results make
comparing the ecosystem condition score for one indi-
vidual cell (300 meters by 300 meters) with another
inappropriate, but this is not the case for comparison
EPA's 2008 Report on the Environment
6-15
-------
INDICAl
Relative Ecological Condition of Undeveloped Land in
EPA Region 5 (continued)
between larger landscapes (U.S. EPA,
2005).
• The model has not yet been field-validated
to ensure that modeled results reflect
actual ecosystem condition.
Data Sources
Maps and frequency distributions for the
three indices were provided by EPA Region
5 (U.S. EPA, 2006). An EPA report available
online contains several related maps produced
by the Critical Ecosystem Assessment Model
(CrEAM), along with a list of the various data-
sets used as inputs for the model (White and
Maurice, 2004, appendices). Results from the
CrEAM model are no longer available as digital
map layers.
References
U.S. EPA (United States Environmental
Protection Agency). 2006. Data provided to
ERG (an EPA contractor) by Mary White,
EPA Region 5. August 3, 2006.
U.S. EPA. 2005. SAB review of the EPA
Region 5 Critical Ecosystem Assess-
ment Model. EPA/SAB/05/011. Wash-
ington, DC.
White, M.L., and C. Maurice. 2004.
CrEAM: A method to predict ecological sig-
nificance at the landscape scale. Chicago, IL:
U.S. Environmental Protection Agency.
Exhibit 6-8. Relative ecological condition of undeveloped land
in EPA Region 5, 1990-1992a
A. Diversity index
',
B. Sustainability index
C. Rarity index
Index score:
Coverage: Undeveloped land in EPA Region 5, based on the 1992 National Land Cover
Dataset (NLCD). For this analysis, "undeveloped" land is any land that the NLCD
classifies as bare rock/sand/clay, deciduous forest, evergreen forest, mixed forest,
shrubland, grasslands/herbaceous, woody wetlands, emergent herbaceous wetlands,
or open water.
Data source: U.S. EPA, 2006
6.2.3 Discussion
What These Indicators Say About Trends
in Extent and Distribution of the Nation's
Ecological Systems
While ecological systems are interconnected and overlapping,
it is useful to discuss trends in terms of major types of sys-
tems. As previously mentioned, there are many ways to define
ecological systems, including by the predominant biota, spatial
scales, and physical characteristics. Most terrestrial systems are
defined by predominant vegetation types. The current extent
of these types has been assessed (see the Land Cover indica-
tor, p. 4-7). Forests form the predominant land cover in the
eastern and north-western U.S. while grasslands, shrublands,
and agricultural lands are the predominant types of vegeta-
tion in the central and western parts of the country. Trends in
forest and wetland ecological systems are considered below.
Trends in land development also are discussed, as this influ-
ences trends in the extent of ecological systems.
Trends in Extent and Distribution of
Forested Ecological Systems
At a national scale, the percentage of forest land has varied
somewhat over the last century with some decreases and some
recent increases (see the Forest Extent and Type indicator,
p. 6-8). Over the same period, shifts in regional distribution
and species composition have occurred. For example, forested
ecological systems decreased in extent in EPA Regions 6 and 9
over the last century, but increased in extent in Regions 1,2,
3, and 5. The complex of tree species within a forest can have
6-16
EPA's 2008 Report on the Environment
-------
a strong influence on the community structure and function-
ing of a forested ecological system, and these assemblages can
change over time. On a broad geographic scale, some forest
types have more than doubled in acreage in the last 50 years—
for example, maple-beech-birch in the eastern U.S. and
fir-spruce in the West. At the same time, some other types of
forest have decreased in acreage. These compositional changes
can be as important as changes in the overall extent of forested
ecological systems.
At a finer regional scale, forest cover in the Puget Sound and
Georgia Basin in the Pacific North-west also was relatively
stable during the 1990s (see the Land Cover in Puget Sound/
Georgia Basin indicator, p. 4-10). However, some of the for-
ested -watersheds experienced a conversion of small amounts
of forest land to some other cover type. As discussed below,
urbanization of low- elevation forested -watersheds is a change
that is receiving particular attention (see the Land Cover in
Puget Sound/Georgia Basin indicator, p. 4-10).
While extent and species composition are important aspects
of forested ecological systems, the spatial arrangement and
contiguity of the systems also influence the functioning of the
systems and the distribution of-wildlife species that use forests
and adjacent areas for habitat. Fragmentation of forested systems
can reduce or redefine the interconnections -within forests,
modifying the scale of habitat and shifting distributions of-wild-
life species. For example, increasing fragmentation due to forest
clearing, development, fires, or other activities creates more
edge habitat and limits the acreage of interior habitat. Groups
of-wildlife species may prefer one habitat over another and
move to maximize the time spent in the preferred habitat type.
Nation-wide, almost one-fifth of forests are highly fragmented
or "patchy," although more than 30 percent of the forests in the
heavily forested Regions 1,2, and 3 are virtually unfragmented
"core" forest (see the Forest Fragmentation indicator, p. 6-11).
Ecosystem connectivity, characterized by ecosystem "hubs"
connected to each other by "spokes" that serve as corridors for
the interaction of biota, -was shown to account for about 40
percent of the land cover in EPA Region 4, the southeastern
U.S. (see the Ecological Connectivity in Region 4 indica-
tor, p. 6-13). In this indicator, connectivity includes not only
forested land but also -wetlands and open -water.
Trends in Extent and Distribution of
Wetland Ecosystems
Wetlands are ecosystems of high biological diversity and
support a number of ecological functions from nursery and
breeding areas to food and protection.16 Whether inland or
coastal, fresh-water or marine, -wetland acreage has declined
over the past 50 years (see the Wetlands indicator, p. 3-32).
The extent of the losses varies by type of-wetland, -with
forested -wetlands losing the most acreage and coastal -wetland
loss slowing somewhat.
Trends in Land Development
"Land use" refers to the visible effects of human use (see the
Land Use indicator, p. 4-14). Changes in land use from forested
or -wetland systems to urban or agricultural environments have
a direct impact on the ecological systems -within -which the
change occurs, as -well as on systems that are interconnected
•with the altered areas (e.g., -watersheds and coastal areas). Some
changes can create edge environments that are favored by cer-
tain -wildlife species. Therefore, trends in land development are
important considerations -with respect to overall trends in the
extent and distribution of ecological systems.
Changes in land use sometimes result in changes in land cover
and conversion from one major ecosystem type to another,
but sometimes they do not. For example, gains in agricultural
productivity have caused significant changes in the extent and
location of crop and pasture land uses. Some land that had
been used for crops or pasture has reverted to forest. Timber
production may convert cropland to forest, or it may do little
more than substitute one forest type or age-class distribu-
tion for another. At the same time, growth in population has
driven an increase in the extent of developed land, much of
•which has converted crop or pasture land to developed land.
At a national scale over the last three decades, crop and
farm acreages have decreased, timberland (productive forest
land) has remained fairly constant, and developed lands have
increased (see the Land Use indicator, p. 4-14). Within the
larger-scale trends, many subtle shifts occur at smaller scales.
The increase in developed lands has received particular atten-
tion in National and Regional Indicators.
Increases in the numbers and changes in the spatial distribu-
tion of human populations explain part of the increase in
developed lands. However, developed land increased by almost
two times the increase in population from 1982 to 2003, sug-
gesting that during this period people -were making a propor-
tionally greater use of the landscape (see the Urbanization and
Population Change indicator, p. 4-19). Geographically, the
rate of development -was four times the population growth rate
in the Northeast, one to three times the population growth
rate in the South and Mid-west, and nearly equal to the growth
rate in the West. The increases in developed land suggest
there -were comparable decreases in other types of lands. To
the extent that these other lands afford habitat to animals and
plants, shifts in land use result in shifts in the extent and distri-
bution of ecological systems. Increases in developed land also
impact physical and chemical factors; for example, more runoff
from impervious surfaces leads to greater loading of nutrients
and contaminants, more unstable hydrology, reduced ground
•water inputs, and increased stream temperatures.
The degree of change in developed lands appears to be associ-
ated \vith types of locations that emerge as focal points for
increasing stress on ecological systems. For example, in the
Puget Sound and Georgia Basin area of the Pacific North-west,
JK-
Dahl,T.E. 2000. Status and trends of wetlands in the conterminous United
States 1986 to 1997. Washington, DC: U.S. Department of the Interior, U.S.
Fish and Wildlife Service.
EPA's 2008 Report on the Environment
6-17
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forest conversion to other types of land use is occurring along
the coast while older growth forests are observed at higher
elevations (see the Land Cover in Puget Sound/Georgia Basin
indicator, p. 4-10). Further, trends indicate that impervious
surface coverage is increasing to the point where detrimental
impacts to aquatic resources may occur.17 In the Great Lakes
region, most of the undeveloped lands occur in the northern
forests or along the major rivers (see the Condition of Unde-
veloped Land in Region 5 indicator, p. 6-14). Proximity to
developed areas has an obvious effect on the quality of these
ecological systems. The highest quality systems make up about
3 percent of the total and are located in the most remote and/
or protected areas.
[Ej Limitations, Gaps, and Challenges
While many of the indicators in this section provide baseline
information, trend information is available for only a few of
the major types of systems—forests and wetlands. There are no
ROE indicators for other types of terrestrial or aquatic systems
including grasslands, shrub lands, and marine hard bottom
communities such as coral reefs, or for finer-scale ecosystem
classifications such as riparian zones or habitat for threatened
and endangered species. Filling these gaps in information would
help EPA to better evaluate trends in ecological condition.
One of the challenges in capturing meaningful changes relates
to location and scale. The importance of location-specific
changes is evident in some of the indices. For example, small
changes in certain areas, such as near-coastal areas of the
Pacific North-west, could have disproportionately large effects
on coastal waters relative to a similar change in the middle of
an expansive prairie. In addition, the appearance of fragmen-
tation in ecological systems depends on the area over which
data were extracted.18 Thus, choosing locations and assessment
areas have obvious impacts on trend assessment. Conversely,
the implications of trends are manifested at scales that are loca-
tion- and area-specific. Important consequences of changes
can be captured or missed depending on how the information
is aggregated and presented.
Another challenge relates to understanding the factors under-
lying changes that occur over various time scales and their
effects on human health and ecological condition. Principal
among these is recognizing that natural cycles and natural
variability bring about changes that may appear as "trends"
over one time scale but will appear as cycles or variations
over longer time scales. Familiar examples include popula-
tion variations among predators and prey or temperature
variations associated with the advance and retreat of ice ages.
Distinguishing these natural cycles and variations from trends
caused by human-induced perturbations is yet another chal-
lenge. In some cases the relationships may be evident, as in
the influence of urbanization on -watersheds or the impact of
Klein, R.D. 1979. Urbanization and stream water quality impairment.Water
Resour.Bull. 15(4):948-963.
USDA Forest Service. 2004. National report on sustainable forests—2003.
Norton, B. 1988. Commodity, amenity, and morality: The limits of quantifica-
tion in valuing biodiversity. In: Wilson, E.O., ed. Biodiversity. Washington, DC:
National Academies Press.
lost sand dunes on subsequent beach erosion. In other cases
factors influencing changes may be difficult to discern, such
as long-term shifts in major plant communities.
6.3 What Are the Trends
in the Diversity and
Biological Balance of
the Nation's Ecological
Systems?
6.3.1 Introduction
Trends in the biological diversity of the nation's ecological
systems can be viewed in terms of both the numbers of spe-
cies present in an ecological system and the extent to -which
some of the species are threatened or endangered. "Biologi-
cal balance" refers to the interrelationships among organ-
isms, including the structure of food webs and the ability of
ecological systems to maintain themselves over time. Balance
is a dynamic characteristic rather than a fixed state.
The biological diversity and balance -within ecological sys-
tems are often used to judge the health of the system, and
their reduction often represents a response to pollutants or
other stressors. Restoring biodiversity and biological bal-
ance has been a focus of EPA's attention over the past three
decades. Reversing declines of species such as the brown
pelican (caused by pesticides) and brook trout (caused by
acid rain), replacing nuisance algal blooms caused by excess
nutrients -with balanced communities of phytoplankton,
replacing beds of sludge worms below -waste-water discharges
•with balanced communities of benthic invertebrates, and
restoring biological communities previously decimated by
improper handling of toxic and hazardous -wastes are well-
known examples.
The significance of biological diversity also stems from the fact
that, for many people, biological diversity contributes to the
quality of life.19 Everyone recognizes the importance of species
as commodities (if those species produce products that can
be bought and sold), and some argue that species have moral
value in and of themselves.
Diversity and biological balance are also of interest because
of how they may influence the functioning and stability
of ecological systems.20-21 While scientists debate the exact
relationship between the diversity and the functioning and
Chapin III, F.S., B.H.Walker, R.J. Hobbs, D.U. Hooper, J.H. Lawton, O.E.
Sala, and D.Tilman. 1997. Biotic control over the functioning of ecosystems.
Science 277(5325):500-504.
Wilson, E.O. 1992.The diversity of life. Cambridge, MA: Belknap Press.
6-18
EPA's 2008 Report on the Environment
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stability of ecological systems, it is generally agreed that as
the number of species in any particular type of ecological
system declines, there is a potential loss of resilience within
that system.22 It is also recognized that these relationships are
not straightforward and can vary in degree depending on the
types of species introduced to or removed from a system.23
Diversity and balance have important time and space compo-
nents. Diversity arises over time as adaptation results in new
species that fill available niches in the environment. This is a
dynamic process involving colonization, evolution of species
adapted to new conditions, and extinction of species that are
less well adapted to a changing environment. This process
has occurred over thousands or millions of years over large
geographic areas, punctuated occasionally by events such
as large meteor impacts, periods of intense volcanism, and
ice ages. Ecological systems that are stable in the short term
evolve into different systems in the long term. Disturbances
that reduce biological diversity or disrupt balance on a small
scale may not have an effect on a larger scale or over longer
time periods.
Changes (decreases and increases) in biological diversity have
likely occurred throughout the history of the U.S. in response
to regional land use changes, water management, intentional
and unintentional introductions of species, and environmental
pollution. Other changes in diversity and the composition of the
biological community can be rapid and dramatic. Introduced
plants and plant pathogens can rapidly transform landscapes
as some species, such as the American chestnut, are lost and
others, such as kudzu, thrive. Introduction of the sea lamprey
to the Great Lakes led to sweeping changes in the entire food
chain, from lake trout all the way down to the phytoplank-
ton.24 Declining sea otter populations led to loss of kelp forests,
as sea urchins formerly preyed upon by otters grazed the kelp
down to the sea floor.25 The decimation of grazers such as the
American Bison or predators such as grizzly bear or wolves has
had cascading impacts on upland vegetation, wetlands, fish, and
other species.26 Toxic chemical pollution can create -wastelands
•where only the most resistant species can survive, and nutrients
and acid rain have had indirect effects on diversity and balance
by causing sweeping changes in the chemical habitat.
Indicators of diversity and biological balance incorporate
information about primary producers and invertebrate and
vertebrate consumers, especially keystone species that play
critical roles in structuring habitat or serve major roles as
primary producers, top predators, or important prey species.
Indicators of invasive species are also important with respect
to assessing trends in diversity and biological balance because
these species can alter the nation's ecological systems by dis-
placing indigenous species, potentially changing the structure
of biological communities.
6.3.2 ROE Indicators
Trends in diversity and balance are evaluated using four
National Indicators and two Regional Indicators (Table 6-3).
The focus for this question is on national- or regional-scale
trends in biological diversity or balance over time spans of
one to three decades. The data on biological diversity and
Table 6-3. ROE Indicators of Trends in Diversity and
Biological Balance of the Nation's Ecological Systems
National Indicators
N/R = National Indicator displayed at EPA Regional scale
Section
Coastal Benthic Communities (N/R)
Benthic Macroinvertebrates in Wadeable Streams
Bird Populations
Fish Faunal Intactness
3.5.2
3.2.2
6.2.2
6.2.2
Regional Indicators Section
Submerged Aquatic Vegetation in the Chesapeake Bay
Non-Indigenous Benthic Species in the Estuaries of the Pacific Northwest
3.5.2
6.2.2
3-44
3-21
6-20
6-21
Page
3-46
6-23
McCann, K.S. 2000.The diversity-stability debate. Nature 405(ll):228-233.
Srivastava, D.S., and M.Vellend. 2005. Biodiversity-ecosystem function
research: Is it relevant to conservation? Annu. Rev. Ecol. Syst. 36:267-294.
Eck, G.W., and L. Wells. 1987. Recent changes in Lake Michigan's fish com-
munity and their probable causes, with emphasis on the role of the alewife
(Alosa pseudoharengus). Can. J. Fish. Aquat. Sci. 44(Suppl. 2):53-60.
Estes, J.A., and J.F. Palmisano. 1974. Sea otters:Their role in structuring near-
shore communities. Science 185:1058-1060.
Pritchard, J.A. 1999. Preserving Yellowstone's natural conditions: Science and
the perception of nature. Lincoln, NE: University of Nebraska Press.
EPA's 2008 Report on the Environment
6-19
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balance come from a variety of sources, including both sys-
tematic monitoring and ad hoc data collection.27 Systematic
probability surveys are now providing national pictures of
the biological diversity of benthic communities in estuar-
ies and in rivers and streams. The Breeding Bird Survey is a
private sector effort that provides valuable national-level data
on trends in bird populations.
Trends involving longer-term effects associated with climate
change are not included. Many issues regarding biodiversity at
subregional and local scales (e.g., tall-grass prairie or the Okefe-
nokee Swamp) that cannot be covered here are no less important.
INDICATOR
:ird Populations
Bird populations are among the most visible biologi-
cal components of ecological systems, supporting a
number of important ecological functions including seed
dispersal, plant pollination, and pest control. Some birds
migrate over entire continents, while others have more
restricted ranges and habitats, but in all cases trends in bird
populations and in the abundance of species integrate the
influences of changes in landscape and habitat, the avail-
ability and quality of food, toxic chemicals, and climate.
The North American Breeding Bird Survey (BBS) began
in 1966 with approximately 600 surveys conducted in the
U.S. and Canada east of the Mississippi River. Today there
are approximately 3,700 active BBS routes across the conti-
nental U.S. and southern Canada (Sauer et al., 1997).
Trends have been computed for observed population sizes
of 418 bird species for the 1966-2003 period (Sauer et al.,
2004). The Audubon Society (2004) categorized each spe-
cies according to its primary habitat: grassland, shrubland,
•woodland, urban, and water and wetlands. This indicator
reflects the number of species with "substantial" increases
or decreases in the number of observations (not a change in
the number of species) for which adequate trend data exist
between 1966 and 2003. Substantial increases or decreases
•were defined for this study as those in which the observed
populations on BBS routes increased or decreased by more
than two-thirds between 1966 and 2003; this designation
does not necessarily imply a statistically significant trend.
What the Data Show
The results point to dynamic changes in observed bird
populations in all habitat types (Exhibit 6-9), although
there were no consistent increases or decreases.
• Of 27 grassland species for which adequate data are
available, only two species (7 percent) showed substan-
tial observed population increases and 19 species (70
percent) showed substantial decreases.
• Of 78 shrubland species for which adequate data are
available, 11 species (14 percent) showed substantial
increases, while 28 species (36 percent) showed substan-
tial declines.
• Of 164 \voodland species for which adequate data are
available, 48 species (29 percent) showed substantial
Exhibit 6-9. Changes in bird populations in the
contiguous U.S. and southern Canada, by
habitat type, 1966-20033
200
175
125
100
75
50
25
=\
Grassland Shrubland Woodland
Urban
Habitat type
Coverage: 418 bird species studied as part
of the North American Breeding Bird Survey
(BBS), which covers the contiguous U.S.
and southern Canada.
Increases or decreases are considered
"substantial" if the observed population on
BBS routes increased or decreased by more
than two-thirds from 1966 to 2003.
Data source: Audubon Society, 2004
Water/
wetland
observed population increases and 42 species (26 per-
cent) showed substantial decreases.
• Of 43 primarily urban species for which adequate data
are available, 17 species (40 percent) showed substantial
observed population increases and 10 species (23 per-
cent) had substantial decreases.
• Of 106 \vater and -wetland bird species for -which ade-
quate data are available, 40 species (38 percent) showed
substantial observed population increases and 14 species
(13 percent) showed substantial decreases.
Indicator Limitations
• The BBS produces an index of relative abundance rather
than a complete count of breeding bird populations. The
There are no systematic national efforts to quantify trends in the diversity of
other vertebrate, invertebrate, plant, or microbial species, but a private sector
organization, NatureServe, working in concert with state Natural Heritage
Programs, has done much to assimilate and integrate data from ad hoc and
systematic studies to assess the status of nearly 40,000 U.S. species and to
quantify populations of more than 20,000 at-risk species.
6-20
EPA's 2008 Report on the Environment
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INDICATOI
Bird Populations (continued)
data analyses assume that fluctuations in these indices of
abundance are representative of the population as a whole.
• The BBS data do not provide an explanation for the
causes of observed population trends. To evaluate popu-
lation changes over time, BBS indices from individual
routes are combined to obtain regional and continental
estimates of trends. Although some species have con-
sistent trends throughout the history of the BBS, most
do not. For example, populations of permanent resident
and short-distance migrant species (birds -wintering pri-
marily in the U.S. and Canada) are adversely affected by
periodic episodes of unusually harsh winter weather.
• Few species have consistent observed population trends
across their entire ranges, so increases or decreases in
this indicator may not reflect the situation across the
entire range of the species.
Data Sources
Trend data were obtained from the Audubon Society's
2004 State of the Birds report (Audubon Society, 2004).
Audubon's analysis used raw data from the National Breed-
ing Bird Survey (USGS, 2004), -which can be downloaded
from http://www.pwrc.usgs.gov/bbs/retrieval/menu.cfm.
References
Audubon Society. 2004. State of the birds USA 2004.
Audubon Magazine September-October.
Sauer, J.R., J.E. Hmes, andj. Fallen. 2004. The North
American Breeding Bird Survey, results and analysis
1966-2003. Version 2004.1. Laurel, MD: USGS Patuxent
Wildlife Research Center.
Sauer, J.R., J.E. Hines, G. Gough, I. Thomas, and E.G.
Peterjohn. 1997. The North American Breeding Bird Sur-
vey, results and analysis. Version 96.4. Laurel, MD: USGS
Patuxent Wildlife Research Center.
USGS (United States Geological Survey). 2004. North
American Breeding Bird Survey. Laurel, MD: USGS
Patuxent Wildlife Research Center. Accessed 2004.
^
Fish Faunal Intactness
Intactness, the extent to which ecological communities
have retained their historical composition, is a critical
aspect of the biological balance of the nation's ecological
systems (NRC, 2000). It is of particular importance in
freshwater systems that are impacted by pollution, habitat
alteration, fisheries management, and invasive species.
This indicator tracks the intactness of the native freshwater
fish fauna in each of the nation's major -watersheds by com-
paring the current faunal composition of those -watersheds
•with their historical composition. In this case, historical data
are based on surveys conducted prior to 1970. The indicator
specifically measures the reduction in native species diversity
in each 6-digit U.S. Geological Survey hydrologic unit code
(HUC) cataloguing unit in the 48 contiguous states. Intact-
ness is expressed as a percent based on the formula:
, , / # of current native species \
reduction m diversity = l — I ——^—. ;—; ;— — I
\# oj historical native speciey
The native species diversity indicator proposed by
the National Research Council (NRC, 2000) com-
pared expected native species diversity (projected from
species-area-curve models) -with observed diversity. This
"Fish Faunal Intactness" indicator makes use of empirical,
rather than modeled, data sets and focuses on a well-known
group of organisms -with a fairly strong historical record.
Reductions in -watershed diversity may be due either to the
overall extinction of a species (at least 12 U.S. fresh-water fish
species are known to be extinct and another three species are
known only from historical records and may be extinct) or,
more commonly, to the extirpation of a species from selected
•watersheds. In the case of regional extirpations, opportu-
nities may exist for restoring a species to -watersheds in its
historical range.
The fish distributional data underlying this indica-
tor -were gathered by NatureServe, a nonprofit research
organization, and are derived from a number of sources,
including species occurrence data from state Natural Heri-
tage Programs, a broad array of relevant scientific literature
(e.g., fish faunas), and expert review in nearly every state.
These data -were assembled during the 1997-2003 period.
The underlying data include distributions for 782 native
fresh-water fish species across small -watersheds (8-digit
HUC). For this indicator, data -were pooled and reported
by larger 6-digit HUCs to reduce potential errors of omis-
sion in the smaller -watersheds.
What the Data Show
Watersheds covering about one-fifth (21 percent) of the
area of the contiguous U.S. appear to have fish faunas
that are fully intact, retaining the entire complement of
EPA's 2008 Report on the Environment
6-21
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w*
INDICATOR
Fish Fauna I Intactness (continued)
Exhibit 6-10. Percent reduction in native fish species diversity in the contiguous U.S. from
historical levels to 1997-20033
Percent of area
in each category
15%
.7%
— 2%
21%
aData are displayed by 6-digit hydrologic unit code (HUC) watershed. Percent reduction is based on the number of
native species present during the period 1997-2003, compared with historical numbers documented prior to 1970. A
species is considered "present" if there is at least one record of its presence in any 8-digit HUC within the 6-digit HUC.
Data source: NatureServe, 2006
fish species that were present before 1970 (Exhibit 6-10).
Watersheds covering nearly a quarter (24 percent) of the
area, however, have lost 10 percent or more of their native
fish species. Reductions in diversity are especially severe in
the South-west (e.g., the lower Colorado River -watershed)
and the Great Lakes, -with eight major watersheds (repre-
senting 2 percent of total area) having lost at least half of
their native fish species.
Some -watersheds are naturally more species-rich than
others, and for those -with greater historical diversity,
even a small percentage reduction may mean the loss of
numerous species in absolute terms. Although the great-
est diversity offish species is found in the Southeast, the
greatest reduction in numbers has occurred in portions of
the Mid-west and the Great Lakes, -where several -watersheds
have lost more than 20 species (Exhibit 6-11). In contrast,
south-western HUCs have all lost 10 or fewer species, but
because these -watersheds historically supported fewer spe-
cies, on a percentage basis their fish faunas are regarded as
less intact.
Indicator Limitations
• The incomplete historical record for fresh-water fish
distributions and inconsistent inventory records for con-
temporary fish distributions are sources of uncertainty.
• Although NatureServe has attempted to compile the
most complete distributional information possible for
these species at the 8-digit HUC level, these data are
dynamic; new records frequently are added and existing
records are revised as new information is received and as
taxonomic changes occur.
Data Sources
This indicator presents a summary of data available from the
NatureServe Explorer database (NatureServe, 2006) (http://
www.natureserve.org/getData/dataSets/watershedHucs/
index.jsp). The identity and status (current vs. historical)
of all native fish species recorded in each 8-digit HUC are
available from this database, along -with species-by-species
distribution maps at the 8-digit HUC level. Analyses based
on these data have previously been reported in Master et al.
(1998, 2003) and Stem et al. (2000).
References
Master, L., A. Olivero, P. Hernandez, and M. Anderson.
2003. Using small -watershed fish, mussel, and crayfish his-
torical and current presence data to describe aquatic bio-
geography and inform its conservation. Abstract #PO67.
Society for Conservation Biology Annual Meeting,
Duluth, Minnesota.
Master, L.L, S.R. Flack, and B.A. Stem. 1998. Rivers of life:
Critical -watersheds for protecting fresh-water biodiversity.
Arlington, VA: The Nature Conservancy.
6-22
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INDICATOI
Fish Fauna I Intactness (continued)
Exhibit 6-11. Reduction in native fish species diversity in the contiguous U.S. from historical
levels to 1997-20033
Percent of area
in each category
aData are displayed by 6-digit hydrologic unit code (HUC) watershed. Reduction is based on the number of native
species present during the period 1997-2003, compared with historical numbers documented prior to 1970. A
species is considered "present" if there is at least one record of its presence in any 8-digit HUC within the 6-digit HUC.
Data source: NatureServe, 2006
NatureServe. 2006. NatureServe explorer. Accessed 2006.
NRC (National Research Council). 2000. Ecological
indicators for the nation. Washington, DC: National
Academies Press.
Stem, B.A., L.S. Kutner, andJ.S. Adams. 2000. Precious
heritage: The status of biodiversity in the United States.
New York, NY: Oxford University Press.
Non-Indigenous Benthic Species in the Estuaries of the
'acific Northwest
Non-indigenous species (NIS) are one of the greatest
threats to aquatic ecosystems and can impact local
and regional economies (Lowe et al., 2000). The number
of invasive species in estuaries of the Pacific North-west
(including Puget Sound, Columbia Estuary, and Coos Bay)
is rising, and these areas can become sources of invasives to
other locales. Coastal waters are particularly vulnerable to
NIS transported in ballast water and introduced via aqua-
culture (Puget Sound Action Team, 2002). It is becoming
apparent that NIS are capable of impacting estuaries along
the Pacific coast, even though they are rarely addressed in
routine monitoring studies. One limitation is the lack of
standardized invasion metrics and threshold values.
This indicator focuses on estuarine soft-bottom commu-
nities of the Columbian Biogeographic Province located
along the Pacific coast from Cape Mendocino, California,
north to the Strait of Juan de Fuca at the entrance to Puget
Sound, Washington. It is limited to sites with salinities of
5 parts per thousand or higher. The indicator is based on
the percent abundance of NIS individuals relative to the
combined abundance of native and NIS individuals in a
benthic grab sample.
The data for this indicator were collected by EPA's Envi-
ronmental Monitoring and Assessment Program (EMAP)
using a probability survey over the 1999-2001 period (Nel-
son et al., 2004, 2005) and by a special probabilistic study
EPA's 2008 Report on the Environment
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w*
INDICATOR
Non-Indigenous Benthic Species in the Estuaries of the
Pacific Northwest (continued)
focusing on estuaries not exposed to ballast water or aqua-
culture. Probability sampling provides unbiased estimates
of the percent abundance of natives and NIS in all estuaries
in the study area, but because the data for the special study
have not yet been statistically expanded, data for this indi-
cator are based on stations sampled rather than area.
Interpretation of this indicator requires threshold val-
ues to distinguish among different levels of invasion. To
determine the lowest expected level of invasion within the
Columbian Biogeographic Province, EPA examined the
extent of invasion in estuaries with minimal exposure to
ballast water discharges and aquaculture of exotic oysters,
•which are the primary invasion vectors in the region.
Using observed percentages of NIS at the minimally
exposed estuaries as a reference, the threshold for "mini-
mally invaded" survey sites was set at 10 percent NIS (i.e.,
sites were classified as minimally invaded if NIS consti-
tuted 0 to 10 percent of the individuals collected). Survey
sites were classified as "highly invaded" if NIS were more
abundant than native species (more than 50 percent NIS)
and as "moderately invaded" if NIS constituted 10 to 50
percent of the individuals.
What the Data Show
Approximately 15 percent of the stations in the Columbian
Province were highly invaded (i.e., abundance of NIS was
greater than abundance of natives) and another 20 per-
cent were moderately invaded (Exhibit 6-12). The EMAP
survey showed that NIS were among the most frequently
occurring anthropogenic stressors in this biogeographic
region when compared to indicators of sediment contami-
nation or eutrophication (Nelson et al., 2004).
The extent of invasion was not uniform, however,
among exposed and minimally exposed estuaries. Estuar-
ies with greater exposure to these invasion vectors were
more invaded; 44 percent of the stations in the exposed
estuaries were moderately to highly invaded compared
to only 21 percent of the stations in minimally exposed
estuaries (Exhibit 6-12). Nonetheless, the observation that
21 percent of the stations in these "pristine" estuaries were
at least moderately invaded indicates that NIS can disperse
•widely once they are introduced into a region, so even
estuaries with no direct exposure to ballast water or aqua-
culture are at risk of invasion.
Indicator Limitations
• This indicator presents baseline data only; trend
information is not yet available.
• Studies in the San Francisco Estuary (Lee et al., 2003)
and in Willapa Bay, Washington (Ferraro and Cole,
in progress) have shown that the percent of NIS can
Exhibit 6-12. Relative abundance of
non-indigenous benthic species in estuaries of
the Pacific Northwest, 1999-2001ab
Extent of invasion:
Minimal0
Moderate11
High6
Percent of estuarine sites in each category:
estuaries
Exposed
estuaries'
Minimally
exposed
estuaries'
65.7 19.9
14.5
56.1 28.6
15.3
79.4 7.4
13.2
Study
area
Coverage: Soft-bottom estuaries
between Cape Mendocino, CA, and
the Strait of Juan de Fuca, WA
(limited to sites with salinity ^5
parts per thousand).
"Totals may not add to 100% due to
rounding.
Minimally invaded: 0-10%
of benthic organisms belong to
non-indigenous species
Moderately invaded: >10-50% of
benthic organisms belong to non-indigenous species
3Highly invaded: >50% of benthic organisms belong to
non-indigenous species
'"Exposed" estuaries have been exposed to ballast water
discharges from international shipping and/or aquaculture of
exotic oysters. "Minimally exposed" estuaries have not.
Data source: U.S. EPA, 2006
vary substantially among different types of soft-bottom
communities—e.g., unvegetated sediment versus sea
grass beds. Thus, regional background values for the
Columbian Province as a whole may not be appropriate
for specific community types.
• This indicator represents percent NIS in individual
benthic grabs of the soft-bottom community, but does
not characterize the total number of NIS in the estuar-
ies. It does not include benthic NIS not subject to grab
sampling, particularly hard substrate organisms.
• The data for the indicator were only collected during
a summer index period and thus do not capture
seasonal variations.
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EPA's 2008 Report on the Environment
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INDICATOI
Non-Indigenous Benthic Species in the Estuaries of the
'acific Northwest (continued)
• The threshold values for "minimally invaded," "moder-
ately invaded," and "highly invaded" are preliminary
and require further research in order to establish their
ecological significance. Specific values may differ in
other biogeographic provinces.
Data Sources
Data for this indicator were collected by two different
studies: EPA's National Coastal Assessment (NCA) and a
special EPA study of minimally exposed estuaries. The
complete results from these studies were not publicly
available at the time this report went to press, but sum-
mary data from the 1999 NCA are available from Nelson
et al. (2004, 2005), and the underlying sampling data can
be obtained from EPA's NCA database (U.S. EPA, 2007)
(http://www. epa.gov/emap/nca/html/data/index. html).
Results from the special study of minimally exposed
estuaries will be published in the near future. Until then,
data for this indicator can be obtained from EPA's Western
Ecology Division (U.S. EPA, 2006).
References
Lee II, H., B. Thompson, and S. Lowe. 2003. Estuarine
and scalar patterns of invasion in the soft-bottom benthic
communities of the San Francisco Estuary. Biol. Invasions
5:85-102.
Lowe, S., M. Browne, S. Boudjelas, and M. De Poorter.
2000. 100 of the -world's worst invasive alien species—a
selection from the Global Invasive Species Database.
Auckland, New Zealand: International Union for the
Conservation of Nature, Invasive Species Specialist Group.
Nelson, W.G., H. Lee II, andj. Lamberson. 2005. Condi-
tion of estuaries of California for 1999: A statistical sum-
mary. EPA/620/R-05/004.
Nelson, W.G., H. Lee II, J.O. Lamberson, V. Engle, L.
Harwell, and L.M. Smith. 2004. Condition of estuaries of
the \vestern United States for 1999: A statistical summary.
EPA/620/R-04/200.
Puget Sound Action Team. 2002. Puget Sound update:
The eighth report of the Puget Sound Ambient Moni-
toring Program (PSAMP). Olympia, WA: Puget Sound
Water Quality Action Team,
U.S. EPA (United States Environmental Protection Agency).
2007. National Coastal Assessment. Accessed 2007.
U.S. EPA. 2006. Data provided to ERG (an EPA
contractor) by Henry Lee, EPA Western Ecology Division.
August 7, 2006.
*
6.3.3 Discussion
What These Indicators Say About Trends in
the Diversity and Biological Balance of the
Nation's Ecological Systems
Few national programs track diversity and biological balance.
However, there are ROE indicators available for invertebrate
communities and select vertebrates (birds and fish) and region-
ally for invasive species (as these can be important disrupters of
ecosystem balance) and important communities of submerged
aquatic vegetation (SAV). Some of these indicators show
reduced or declining diversity for particular groups of animals
and plants, but this is not consistent across all the ROE indi-
cators. The particular trends of available ROE indicators are
discussed below by plant and animal groupings, followed by the
limitations of the available information and future challenges.
Primary Producers
Primary producers range from the microscopic plants of
the oceans to the giant red-woods of California. The types
of plants and the biomass they produce are fundamental to
ecological systems. For example, SAV is an important biologi-
cal component of aquatic systems, contributing to diversity
and balance by providing habitat and food. While there is no
National Indicator of trends in SAV, the SAV in Chesapeake
Bay indicator (p. 3-46) provides data on trends in an impor-
tant regional ecosystem. SAV has increased in the Bay over
the past 25 years, but remains below its historical coverage.
Contributing factors in the Bay include excessive nutrients,
sediment loads, diseases, and physical disturbance.
Invertebrates
Invertebrates such as -worms, insects, and crustaceans are
among the most diverse group of organisms. Collectively
they make up the largest component of animal biomass on the
planet and are critical components of aquatic and terrestrial
food \vebs. Trends in the composition of invertebrate commu-
nities can reflect important environmental changes.
In the nation's coastal systems, baseline measures of inverte-
brate biodiversity and species composition indicate that about
one-fifth of estuarine area exhibits low biological condition
EPA's 2008 Report on the Environment
6-25
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(see the Coastal Benthic Communities indicator, p. 3-44).
Because benthic invertebrates live on or in sediments, it is not
surprising that many of these areas also exhibit low sediment
and/or-water quality. For small streams, the benthic macro-
invertebrate Index of Biological Integrity exhibits a broad
distribution from low to high values (see the Benthic Macro-
invertebrates in Wadeable Streams indicator, p. 3-21).
Vertebrates
The biodiversity offish, amphibians, reptiles, birds, and
mammals is influenced by available food resources, the size
and arrangement of suitable habitats, influxes of new species,
climate and -weather, and the presence of contaminants. Ver-
tebrates often receive much attention because they are highly
visible and are often near the top of the food chain.
Among vertebrates the most reliable indicator of national
trends is for birds, -which have been tracked since 1966 (see the
Bird Populations indicator, p. 6-20). Bird populations are in
dynamic flux. There appears to be a net decline of observed
populations most commonly found in grasslands and shru-
blands, comparable increases and decreases in observed popu-
lations in -woodlands, and some gains in observed populations
inhabiting urban and water/wetlands areas.
Fish are distributed throughout most of the nation's aquatic
and marine ecological systems. Comparisons between current
and historical species compositions (see the Fish Faunal Intact-
ness indicator, p. 6-21) indicate that one-fifth of the -water-
sheds of the contiguous 48 states retain their full complement
offish species, -while about a quarter have experienced a loss
in species of 10 percent or more. Absolute losses have occurred
primarily in the Mid-west and the Great Lakes, -while on a
percentage basis, losses have been highest in the Great Lakes
and the South-west.
Invasive Species
The infiltration of new species into areas is a natural phe-
nomenon but can be accelerated through intentional and
unintentional introductions. Introduction of species such as
kudzu, zebra mussels, grass carp, starlings, and nutria have
had profound effects on ecological systems.28 Many newly
introduced species may lack predators or parasites that kept
these species under control in their native habitats, allow-
ing them to out-compete resident species and even dominate
entire systems. While national data are lacking, the Non-
Indigenous Estuarine Species in Pacific North-west indica-
tor (p. 6-23) shows that in the Columbian Biogeographic
Province (from California to Washington), about one-third
of the stations sampled -were highly or moderately invaded
•with non-indigenous invertebrates.
28 Lowe, S., M. Browne, S. Boudjelas, and M. De Poorter. 2000. 100 of the
world's worst invasive alien species: A selection from the Global Invasive Spe-
cies Database. Auckland, New Zealand:World Conservation Union, Invasive
Species Specialist Group.
29 Madsen, J.D., J.W Sutherland, J.A. Bloomfield, L.W Eichler, and C.W Boylen.
1991. The decline of native vegetation under dense Eurasian water-milfoil
canopies.]. Aquat. Plant Manage. 29:94-99.
30 Lake Champlain Basin Program Federal Agencies Work Group. 2005.
Limitations, Gaps, and Challenges
A number of additional ROE indicators would help EPA bet-
ter address the question of trends in diversity and biological
balance. While there are ROE indicators for the extent and
distribution of vegetation types, there remain gaps with respect
to indicators of plant biodiversity in terrestrial and aquatic eco-
logical systems, including both vascular and non-vascular plants.
There is no ROE indicator for threatened and endangered
species. Also, there are no ROE indicators for algal blooms in
coastal \vaters, nor are there any comparable indicators for fresh-
water systems—e.g., the extent of nuisance aquatic plants such
as the prolific growths of Eurasian milfoil and water chestnut in
lakes and ponds, which continue to create water management
problems.29'30 ROE indicators of climate-related vegetation
changes also are lacking (e.g., fluctuations in the extent of kelp
beds along the Pacific coast related to El Nino events).31
There are no ROE indicators for major groups of vertebrate
biota including amphibians, reptiles, and mammals. Because
amphibians live both on land and in the water, their diversity
and trends in their abundance could be influenced by a wide
range of stressors to air, water, and land. Recent reported
declines in amphibian populations worldwide indicate that
losses are attributable in some areas primarily to overharvest-
ing, in others to loss of habitat, and in still others to unknown
causes,32 but at this time there is no National Indicator that
meets the criteria for this report. There also are no ROE indi-
cators for trends in important insect and freshwater shellfish
species, coastal fish and shellfish communities, microbial com-
munities in soil and water, or genetic diversity in plant and
animal populations, which could affect their viability when
stressed by contaminants or habitat alteration.
Modern transportation and international trade in biota for
food have caused invasive species to remain a potentially
important but poorly quantified source of stress to the diver-
sity and balance of native species. While the Non-Indigenous
Estuarine Species in Pacific North-west indicator (p. 6-23) pro-
vides some insight into the potential importance of invasive
species, the full significance of accelerated species introduc-
tions is not captured by any ROE indicator.
In addition to indicator gaps and limitations, there are chal-
lenges to developing indicators of biological diversity and
balance even if the data -were available. For example, establish-
ing an appropriate time scale for assessing trends in diversity
and balance poses a major challenge. Biological variation is
expected at annual, decadal, and even longer time scales.
Because of the limited time frames over-which observations
have been made, parsing normal fluctuations in diversity and
balance from longer-term trends is difficult. In addition, the
level of interest and care of observation can change -with time,
confounding the determination of actual trends.
Opportunities for federal action: Managing aquatic non-native nuisance plants
and animals,
31 Dayton, P.K., and M.Tegner. 1984. Catastrophic storms, El Nino,
and patch stability in a southern California kelp community. Science
224(4646):283-285.
32 Stuart, S.N., J.S. Chanson, N.A. Cox, B.E.Young, A.S.L. Rodrigues, D.L.
Fischman, and R.W Waller. 2004. Status and trends of amphibian declines and
extinctions worldwide. Science 306(5702):1783-1786.
6-26
EPA's 2008 Report on the Environment
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Appropriate spatial scales are equally important. Regional Indi-
cators provide helpful insights into stressors affecting diversity
and biological balance in some kinds of ecological systems
for which there are no National Indicators. In fact, because
many ecological systems vary so much by geographic region,
compilations of Regional Indicators may provide the only
rational approach for identifying meaningful trends. Especially
important examples for biological diversity are unique ecosys-
tems such as the Arctic and Pacific islands. Trends in physical
characteristics and processes can have far-reaching effects. For
example, polar bears represent important keystone species in
the nation's Arctic regions, where they are stressed by -warm-
ing of coastal waters that limit the duration of ice formation.
Pacific island biota are stressed by invasive species and a num-
ber of other stressors.
6.4 What Are the
Trends in the Ecological
Processes That Sustain
the Nation's Ecological
Systems?
6.4.1 Introduction
Ecological systems are sustained by a number of biological,
physical, and chemical processes. Collectively, these processes
produce organic matter using energy (photosynthesis and
chemosynthesis), transfer carbon and nutrients (through food
webs and through decomposition), drive soil formation, and
enable the reproduction of organisms (e.g., through pollination
of plants by insects). Ecological processes also play an important
role in providing ecological services such as the provision of
natural resources and regulation of air and water quality.33
Ecological processes influence the extent, distribution, and
biodiversity of systems. If primary production declines, energy
flow to higher trophic levels is diminished, potentially com-
promising the sustainability of animal populations dependent
on plants for food. Primary production is influenced by the
availability of nutrients. Decreases and increases in nutrients
can affect the amounts of primary production as well as the
types of plants that grow, with subsequent effects on animals.
The successful reproduction of plants and animals depends on
the physical and chemical regimes of their environment.
Too much primary production can also cause problems, such
as those that occur in eutrophic lakes that experience an
overload of nutrient inputs. Eutrophic conditions can alter
the composition of animal and plant life and result in reduced
oxygen levels due to decomposition of organic matter. For
these reasons, management of nutrient inputs is commonly
driven by the potential for excessive plant growth.
Primary production and associated carbon cycling (which
form the base of food webs), nitrogen cycling (e.g., ammoni-
fication and nitrification), nutrient cycling (e.g., phosphorous
and other essential elements for sustainability of carbon-based
life), and hydrogen/oxygen cycles (implicating hypoxic/anoxic
conditions) are fundamental ecological processes within
systems. Processes related to the production, transfer, and loss
of biomass and the reproduction and death rates of individu-
als within populations are reflected in various "end states" in
time, snapshots of the outcomes of integrated processes. The
standing stock of a population or the amounts and types of
carbon stored within an ecological system are measures of
these end states. While not processes themselves, trends in end
states provide some insight into the relative balance among
processes. Carbon storage in forests, discussed in this section,
is an example of such an end state.
EPA has long been concerned with the impacts of human
activities that can affect the rates, types, and timing of
ecological processes. In particular, activities that upset the
balance between primary production and respiration (e.g.,
biochemical oxygen demand, nutrients from fertilizers and
human waste, and the effects of ultraviolet radiation) and
activities that affect sediment erosion and transport are
important factors in water quality management. Many pesti-
cides, chemicals used in industry, pollutants, and waste prod-
ucts have the potential to interfere with species reproduction
(one of the most important of ecological processes). At local
and regional scales, changes in land use that alter the extent
and distribution of ecological systems (Section 6.2) directly
affect ecological processes within and adjacent to particular
areas. Concomitant changes often occur in primary produc-
tion, nutrient cycling, and erosion and sediment transport.
For example, shifts from forested to urban or agricultural
lands influence the amounts and types of primary produc-
ers, the infiltration of water into soils, and the storage and
cycling of carbon and nutrients.
Table 6-4. ROE Indicators of Trends in the Ecological Processes
That Sustain the Nation's Ecological Systems
National Indicators
Carbon Storage in Forests
Section
6.4.2
6-28
Millennium Ecosystem Assessment. 2005. Ecosystems and human well-being:
Current state and trends.Washington, DC: Island Press.
EPA's 2008 Report on the Environment 6-27
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6.4.2 ROE Indicators
This section uses one National Indicator (Table 6-4) to
examine trends in the ecological processes that sustain ecolog-
ical systems. Information for this indicator comes from satellite
remote sensing, geographic information systems, and inde-
pendent field studies conducted as part of the US DA Forest
Service Forest Inventory and Analysis. It is important to note
that the data presented for carbon storage in forests include
only forests classified as "timberland," which excludes about
one-third of U.S. forest land cover. Timberland is defined as
forests capable of producing at least 20 cubic feet per acre per
year and not withdrawn from timber utilization by regulation
or statute. This is an important distinction between previously
illustrated trends in forest extent and type and the following
discussion of carbon storage.
INDICATOR
Carbon Storage in Forests
After carbon dioxide is converted into organic matter by
photosynthesis, carbon is stored in forests for a period
of time in a variety of forms before it is ultimately returned
to the atmosphere through the respiration and decomposi-
tion of plants and animals, or harvested from forests for use
in paper and wood products. A substantial pool of carbon
is stored in woody biomass (roots, trunks, and branches).
Another portion eventually ends up as organic matter in
forest floor litter and the upper soil horizons. Carbon stor-
age in forest biomass and forest soils is an essential physical
and chemical attribute of stable forest ecosystems, and a
key link in the global carbon cycle.
This indicator, developed by the U.S. Department of
Agriculture (USDA) Forest Service, tracks decadal changes
in net carbon storage rates in the pools of living and dead
biomass in forests in the contiguous 48 states. The carbon
pools for this indicator are estimated using USDA Forest
Service Forest Inventory and Analysis (FIA) data from five
historical periods (circa 1953, 1963, 1977, 1987, and 1997).
These data cover forest classified as "timberland" under
FIA data collection procedures—that is, forests capable of
producing at least 20 cubic feet per acre per year of industrial
•wood and not withdrawn from timber utilization by statute
or regulation. Timberland makes up roughly two-thirds of
U.S. forest land. Alaska and Hawaii are not included because
of limited historical data. The FIA program estimates
carbon storage using on-the-ground measurements of tree
trunk size from many forest sites; statistical models that
show the relationship between trunk size and the weight of
branches, leaves, coarse roots (greater than 0.1 inch in diam-
eter), and forest floor litter; and estimates of forest land area
obtained from aerial photographs and satellite imagery. Val-
ues are converted into carbon storage based on coefficients
derived from previous field studies (Smith and Heath, 2002;
Smith et al, 2003; Birdsey, 1996). Forest floor litter is com-
posed of dead organic matter above the mineral soil hori-
zons, including litter, humus, and fine woody debris. Larger
branches and logs on the ground are counted as "down dead
•wood." Organic carbon in soil is not included.
What the Data Show
The change in carbon inventories from year to year—i.e.,
net storage—reflects increases in growth as well as decreases
Exhibit
storage
6-13. Average annual net carbon
in forests of the contiguous U.S., by
forest component, 1 953-1 996a
CD
O)
o _ 200
= ^
_§ c:
o T->
C CD
•re E 100
1J
ro : —
§> E 50
0
0
1953-1962 1963-1976
1977-1986
1987-1996
Reporting period
Coverage: Forest land
classified as "timberland,"
which accounts for
approximately two-thirds
of the forest land of the
contiguous 48 states.
These data do not include
carbon stored in forest soi
Data source: USDA Forest
Service, 2004a,b
D Aboveground live trees
D Aboveground standing
dead trees
D Understory vegetation
D Down dead wood
(including stumps)
D Forest floor litter
D Belowground live trees (roots)
D Belowground dead wood
due to harvesting, land use change, and disturbances such
as fire, insects, and disease. Overall, net carbon storage in
forests of the contiguous 48 states has been positive since
1953 (Exhibit 6-13), indicating that over at least the last
half-century, forests have served as a sink rather than a
source of carbon. The average rate of net carbon storage in
forests increased between the 1950s and the 1980s, peaking
at 210 million metric tons of carbon per year (MtC/yr) from
1977 to 1986. The rate declined to 135 MtC/yr for the last
period of record (1987-1996), with declining storage evident
in live, dead, and understory pools. This decline is thought
6-28
EPA's 2008 Report on the Environment
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INDICATOI
Carbon Storage in Forests (continued)
Exhibit 6-14. Average annual net carbon storage in forests of
the contiguous U.S. by region, 1953-1996a
100
50
25
-25
i North
i South
Rocky
Mountains
i Pacific
Coast
1953-1962
1963-1976
1977-1986
Reporting period
1987-1996
Rocky
Mountains
Coverage: Forest land classified as
"timberland," which accounts for
approximately two-thirds of the forest land
of the contiguous 48 states. These data do
not include carbon stored in forest soil.
Data source: USDA Forest Service,
2004a,b
to be due to a combination of increased harvests relative
to growth, more accurate data, and better accounting of
emissions from dead wood (USDA Forest Service, 2004b).
The rate of storage over this period is equivalent to approxi-
mately 9 to 10 percent of U.S. carbon dioxide emissions
over a comparable period (U.S. EPA, 2005).
Carbon storage trends vary among regions of the coun-
try, depending on land use patterns and factors such as
climate and soil quality. In three of the four major regions,
net storage was positive throughout the period of record,
•with the North generally showing the largest net storage
rates (Exhibit 6-14). The exception was the Pacific Coast
region, which experienced net losses of forest carbon dur-
ing two of the four reporting periods. Rates of net carbon
storage appear to have decreased over time in the South;
this trend is thought to be due to an increase in harvesting
relative to growth (USDA Forest Service, 2004b). Some of
the harvested carbon is sequestered in wood products.
Indicator Limitations
• The data include only forest classified as "timberland,"
•which excludes about one-third of U.S. forest land
cover. Historical data from Alaska and Hawaii are insuf-
ficient for inclusion in this indicator.
• Data are derived from state inventories that do not cor-
respond exactly to the years identified in Exhibits 6-13
and 6-14.
• Carbon stored in forest soil is not
included.
• Carbon pools are not measured, but are
estimated based on inventory-to-carbon
coefficients developed with information
from ecological studies. These coefficients
may change over time as new ecologi-
cal studies are conducted, which could
change storage rate estimates.
These limitations are discussed in detail
in Heath and Smith (2000) and Smith and
Heath (2000, 2001).
Data Sources
Exhibits 6-13 and 6-14 were previously pub-
lished in the data supplement to USDA For-
est Service (2004b). The numbers depicted
in these figures have not been published, but
•were provided by the USDA Forest Service
(2004a). The physical measurements used
as inputs in the carbon storage models can
be obtained from the FIA database (USDA
Forest Service, 2005) (http://fia.fs.fed.us/
tools-data/).
References
Birdsey, R.A. 1996. Carbon storage for
major forest types and regions in the conterminous United
States. In: Sampson, R.N., and D. Hair, eds. Forests and
global change, volume 2: Forest management opportunities
for mitigating carbon emissions. Washington, DC: Ameri-
can Forests, pp. 1-25, 261-308.
Heath, L.S., andJ.E. Smith. 2000. An assessment of uncer-
tainty in forest carbon budget projections. Environ. Sci.
Policy 3:73-82.
Smith, J.E., and L.S. Heath. 2002. Estimators of forest
floor carbon for United States forests. Res. Pap. NE-722.
Newtown Square, PA: USDA Forest Service, Northeastern
Research Station. 37 pp.
Smith, J.E., and L.S. Heath. 2001. Identifying influences
on model uncertainty: An application using a forest carbon
budget model. Environ. Manage. 27:253-267.
Smith, J.E., and L.S. Heath. 2000. Considerations for
interpreting probabilistic estimates of uncertainty of
forest carbon. In: Joyce, L.A., and R. Birdsey, eds. The
impact of climate change on America's forests. General
Technical Report RMRS-59. Fort Collins, CO: USDA
Forest Service, Rocky Mountain Research Station.
pp. 102-111.
Smith, J.E., L.S. Heath, and J.C. Jenkins. 2003. Forest
volume-to-biomass models and estimates of mass for live
EPA's 2008 Report on the Environment
6-29
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INDICATOR
Carbon Storage in Forests (continued)
and standing dead trees of U.S. forests. General Techni-
cal Report NE-298. Newtown Square, PA: USDA Forest
Service, Northeastern Research Station. 57 pp.
USDA Forest Service. 2005. Forest Inventory and Analysis
(FIA) database. Accessed 2005.
USDA Forest Service. 2004a. Data provided to ERG (an
EPA contractor) by Linda Heath, USDA Forest Service.
December 23, 2004.
USDA Forest Service. 2004b. National report on sus-
tainable forests—2003. (main site); (data supple-
ment: summary); (data supplement:
graphics and metadata)
U.S. EPA (United States Environmental Protection
Agency). 2005. Inventory of U.S. greenhouse gas emissions
and sinks: 1990-2003. EPA/430/R-05/003.
6.4.3 Discussion
What This Indicator Says About Trends in
the Ecological Processes That Sustain the
Nation's Ecological Systems
The ROE indicator provides data on trends in primary pro-
duction and carbon cycles for terrestrial systems.34 Primary
producers capture, store, and supply solar-derived energy to
other species in the system. In the forest, the energy cur-
rency is organic matter. Primary producers convert carbon
dioxide into organic matter, which is then available to spe-
cies throughout the ecological system as an energy resource
and ultimately returns to the atmosphere (see the Carbon
Storage in Forests indicator, p. 6-28). For forests, the stabil-
ity of the system may depend on the balance between carbon
stored in standing stock and carbon lost from the system due
to harvesting. Net carbon storage has been positive for the
last half-century, reflecting an overall gain in forest biomass.
The rate of net storage increased between the 1950s and the
1980s, then declined through the mid-1990s. During the
1987-1996 time period, the greatest carbon storage occurred
in the North and Rocky Mountain regions where there is
more tree growth relative to harvesting, while the greatest
decline in storage rates occurred in the South where harvest-
ing has been increasing relative to growth. The distribu-
tion of carbon has received much attention, not only from a
biological point of view but also with respect to global cycles
of carbon. Increases and decreases in carbon storage sug-
gest that other pools of carbon (e.g., within the aquatic and
atmospheric environments) are also changing. The distribu-
tion of carbon among all these pools reflects a combination
of processes and can also influence other chemical, physical,
and biological processes.
Limitations, Gaps, and Challenges
Carbon storage trends are important for assessing the future
viability of ecological systems, and they have increasing utility
in evaluating global carbon cycles and potential climate change.
At this time, however, ROE indicators are not available for car-
bon storage in systems other than forests (e.g., grasslands), and
the indicator presented here is restricted to timberland (versus
all forest) and does not include carbon storage in soil. Direct
measurement can pose a challenge; in this case, statistical mod-
els must be employed to estimate carbon storage relationships
among different components of the forest ecosystem.
A further limitation of the indicator presented here is that
it provides very little insight into other ecological processes
across the nation. Indicators are lacking for primary produc-
tion, nutrient cycling (e.g., nitrogen fixation and denitrifica-
tion), secondary production, and reproduction and growth
rates of populations. Indicators also are lacking for processes
such as pollination, decomposition, and removal of contami-
nants from air and water. EPA recognizes this as a gap in
understanding trends in ecological processes. To some degree,
information presented in Sections 6.2 and 6.3 gives insight
into the net result of ecological processes. Trends in the extent
and distribution of ecological systems and in the biodiver-
sity and balance of those systems reflect underlying processes
that produce food, cycle nutrients, and sustain populations of
plants and animals. Sections 6.2 and 6.3 can be thought of as
addressing "end states" that indicate the results of underly-
ing ecological processes. Trends in these end states may or
may not pick up important trends in the underlying processes
because systems are dynamic and internal relationships are
rarely linear. Indicators of ecosystem stability or resilience are
potentially important gaps in this regard.
Whitmarsh, J., and Govindjee. 1999.The photosynthetic process. In: Singhal.
G.S., G. Renger, S.K. Sopory, K.D. Irrgang, and Govindjee, eds. Concepts in
photobiology: Photosynthesis and photomorphogenesis. New Delhi, India:
Narosa Publishers; Dordrecht,The Netherlands: Kluwer Academic Publishers.
pp. 11-51.
6-30
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6.5 What Are the
Trends in the Critical
Physical and Chemical
Attributes of the Nation's
Ecological Systems?
6.5.1 Introduction
Physical and chemical attributes influence and sustain ecologi-
cal systems. Critical physical attributes include temperature,
light, and hydrology (rainfall, soil moisture, flow rates, and
sea level), as well as infrequent physical events that reshape
ecological systems, such as fires, floods, and storms. Examples
of critical chemical attributes include oxygen, nutrients, pH,
salinity, and the presence of other chemicals in the environ-
ment.35 Together, these attributes have driven the evolutionary
history of species, and they continue to drive ecological pro-
cesses, shape the conditions in which species live, and govern
the very nature of ecological systems.
Species have evolved within particular physical and chemical
environments. These are characterized by mean (i.e., long-
term average) conditions as well as by fluctuations on time
scales of a day (e.g., tidal and light/dark cycles), seasons (e.g.,
temperature and hydrological cycles), years (e.g., periodic
climatic and fire events), and longer time scales. The occur-
rence of ice ages every 40,000 to 100,000 years reflects one
of the longer time scales. Because critical physical and chemi-
cal attributes influence so many aspects of ecological systems,
small changes in average conditions or changes in temporal
variations can potentially have large effects on the extent and
distribution of ecological systems and on the biodiversity of
these systems.
Average conditions and the degree and periodicity of fluc-
tuations in physical and chemical attributes vary over the
surface of the globe, and species have evolved with specific
niche requirements that reflect the physical and chemical
states of the ecological systems in which they live. For this
reason, a species that has evolved in tropical waters would
have temperature requirements that are higher and nar-
rower (the species is less able to tolerate fluctuations) than a
species that has evolved in temperate waters where temper-
atures are lower and more variable. Reproduction and other
activity patterns of species are often related to physical
and chemical cues such as temperature, light, and salinity.
Because species have evolved coincident with the presence
Information on nutrients and potentially toxic chemicals is presented in
Chapters 2, 3, and 4 of the ROE.
Millennium Ecosystem Assessment Board. 2005. Living beyond our means:
Natural assets and human well being,
(or absence) of physical disturbances, reproductive strategies
may be linked with the occurrence of events that other-wise
appear destructive. Thus, disturbances such as periodic fires
or flooding may be essential for sustaining certain species
and ecological systems where these disturbances have been
present over evolutionary time scales.
Critical physical attributes reflect, in part, the influence of
solar radiation. Solar radiation warms land and water masses
and drives hydrologic cycles. The amount of light reach-
ing the surface of the Earth and penetrating into its waters
determines levels of photosynthesis, which is essential to the
support of biological systems. Other examples of physical,
chemical, and biological processes that are influenced by the
amount and periodicity of light include temperature and
\veather conditions, photoactivation of chemicals, muta-
tions, and the timing of reproductive cycles. Solar radiation
can also have potentially harmful effects on some spe-
cies. Light regimes can be influenced by changes in solar
energy reaching the earth, changes in the transparency of
•water, and changes in sea level, which in turn can change
the degree of light penetration reaching the sea floor, coral
reefs, and kelp forests. The implication of climate change for
changes in many aspects of ecological condition has received
broad attention.36-37
EPA has been actively involved over its three decades in
assessing and managing factors that alter the critical chemi-
cal and physical characteristics of ecological systems (e.g.,
temperature, pH, electrochemical [redox] potential, and the
transparency of air and water). For example, the use of water
for cooling purposes can result in temperature increases in
receiving waters of a river, acid rain can lower the pH levels
of lakes in sensitive regions, and -waste-water and fertilizer can
lead to low redox potentials, -which affect biological commu-
nities and the cycling of both toxic and non-toxic materi-
als. Although EPA is not directly involved in the control of
hydrology—an important physical factor in the environ-
ment—hydrology greatly influences the fate and transport of
pollutants in aquatic ecosystems. Changes in such factors as
the amount of runoff or snowpack can affect ground -water
levels as -well as flows into streams and rivers. Flood control
efforts can alter flooding and sedimentation processes that
sustain particular types of systems. Because ground -water is
a primary source to surface -water bodies in many parts of
the nation, changes in the quantity (water level) and quality
of ground -water influence ecological conditions not only in
the hyporheic zone (below and adjacent to the stream bed)
but also in surface -waters. The potential impacts of climate
change (-whether natural or human-induced) have important
consequences for virtually every aspect of ecological struc-
ture and function.
Intergovernmental Panel on Climate Change. 2007. Climate change 2007:
Impacts, adaptation and vulnerability. Contribution ofWorking Group II
to the fourth assessment report of the Intergovernmental Panel on Climate
Change. Cambridge, UK: Cambridge University Press,
JK-
EPA's 2008 Report on the Environment
6-31
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Table 6-5. ROE Indicators of Trends in the Critical
Physical and Chemical Attributes of the Nation's Ecological Systems
National Indicators Section
U.S. and Global Mean Temperature and Precipitation
Sea Surface Temperature
Streambed Stability in Wadeable Streams
High and Low Stream Flows
Sea Level
Nitrogen and Phosphorus Loads in Large Rivers
Nitrogen and Phosphorus in Wadeable Streams
Nitrogen and Phosphorus in Streams in Agricultural Watersheds
Lake and Stream Acidity
6.5.2
6.5.2
3.2.2
3.2.2
6.5.2
3.2.2
3.2.2
3.2.2
2.2.2
Regional Indicators Section
Hypoxia in the Gulf of Mexico and Long Island Sound
3.5.2
Page
6-32
6-37
3-11
3-8
6-39
3-17
3-13
3-15
2-42
Page
3-48
6.5.2 ROE Indicators
The evaluation of trends in the critical physical and chemical
attributes of the nation's ecological systems relies primar-
ily on nine National Indicators and one Regional Indicator
(Table 6-5). Information comes from a variety of sources,
including satellite remote sensing, geographic information
systems, monitoring programs, visual surveys, and independent
field studies. Indicator data in this section are drawn from a
variety of programs such as EPA's Wadeable Streams Assess-
ment (WSA), National Aeronautics and Space Administration
(NASA) remote sensing, the National Oceanic and Atmo-
spheric Administration's (NOAA's) National Climatic Data
Center and tidal gauge net-work, and the U.S. Geological Sur-
vey's (USGS's) National Water Quality Assessment (NAWQA)
program and stream gauge net-work.
INDICATOR
U.S. and Global Mean Temperature and Precipitation
Air temperature and precipitation are two important
properties of climate and are the most -widely measured
variables. Changes in these indicators may have -wide-
ranging direct or indirect effects on ecological condition
and human health. These impacts may be positive or nega-
tive, depending on the effect, the magnitude of change,
and the location. For example, changes in temperature can
affect heat- and cold-related mortality and illness due to
altered frequency and magnitude of heat -waves and cold
spells. Changes in temperature may also change the range
and distribution of animal and plant species. Precipitation
changes affect -water availability and quality, -which can
have important effects on agricultural, forest, animal, and
fisheries productivity, as -well as human nutrition. Indirect
effects of temperature and precipitation changes include
changes in the potential transmission of vector-borne
infectious diseases. These may result from alterations in the
ranges and seasons of animals that carry disease or from
accelerated maturation of certain infectious parasites.
This indicator shows trends in temperature and precipi-
tation based on instrumental records from 1901 to 2006
(except for Alaska and Hawaii, -where records begin in
1918 and 1905, respectively). Air temperature and precipi-
tation trends are summarized for the contiguous U.S., as
•well as for 11 climate regions of the U.S., including Alaska
and Hawaii (these climate regions are different from the
ten EPA Regions). For context, this indicator also shows
trends in global temperature (over land and sea) and global
precipitation (over land) from 1901 to 2006.
Temperature and precipitation data are presented as
trends in anomalies. An anomaly represents the difference
between an observed value and the corresponding value
from a baseline period. This indicator uses a 30-year base-
line period of 1961 to 1990. To generate the temperature
time series, measurements -were converted into monthly
anomalies, in degrees Fahrenheit. The monthly anomalies
then -were averaged to get an annual temperature anomaly
for each year. Precipitation trends -were calculated in
similar fashion, starting -with anomalies for total monthly
precipitation, in millimeters. Monthly anomalies -were
added to get an annual anomaly for each year, -which -was
then converted to a percent anomaly—i.e., the percent
6-32
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INDICATOR
LS. and Global Mean Temperature and Precipitation (continued)
Exhibit 6-15. Annual temperature anomalies in
the contiguous U.S. and worldwide, 1901-20063
A. Contiguous U.S. temperature anomalies
E
O
<
1901-2006 trend: +1.17°F per century
1977-2006 trend: +5.92°F per century
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Year
B. Global temperature anomalies
1901-2006 trend:+1.16°F per century
1977-2006 trend: +3.05°F per century
4*
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Year
Anomalies are calculated with respect to the 1961-1990 mean.
Data source: NOAA, 2007b
departure from the average annual precipitation during the
baseline period. Trends in temperature and precipitation
•were calculated from the annual time series by ordinary
least-squares regression. For each of the 11 climate regions,
this indicator also shows a smoothed time series, which was
created from the annual series using a nine-point bino-
mial filter (4 years on each side, averaged with decreasing
•weights further from the center year).
What the Data Show
Since 1901, temperatures have risen across the contigu-
ous U.S. at an average rate of 0.12°F per decade (1.2°F per
century) (Exhibit 6-15, panel A). Over the past 30 years,
average temperatures rose at an increased rate of 0.59°F
per decade, and 5 of the top 10 warmest years on record
for the contiguous U.S. have occurred since 1990. The
overall warming trend is not confined to just a few anoma-
lous years, as the last eight 5-year periods (2002-2006,
2001-2005, ...1995-1999) were the eight warmest 5-year
periods on record (NOAA, 2007a). Warming occurred
throughout the U.S., with all but three of the 11 climate
regions (all but the Central, South, and Southeast) show-
ing an increase of more than 1°F since 1901 (Exhibit 6-16).
The greatest temperature increase occurred in Alaska
(3.3°F per century).
Trends in global temperature and precipitation provide a
context for interpreting trends in temperature and precipita-
tion in the U.S. Instrumental records from land stations and
ships indicate that global mean surface temperature rose by
about 1.2°F during the 20th century (Exhibit 6-15, panel B),
similar to the rate of warming within the contiguous U.S.
During the last three decades, however, the U.S. warmed at
nearly twice the global rate.
As global mean temperatures have risen, global mean
precipitation also has increased (Exhibit 6-17, panel B).
This is expected because evaporation increases with
increasing temperature, and there must be an increase in
precipitation to balance the enhanced evaporation (IPCC,
2007). Globally, precipitation over land increased at a
rate of 1.7 percent per century since 1901, but the trends
vary spatially and temporally. Over the contiguous U.S.,
total annual precipitation increased at an average rate of
6.5 percent per century since 1901 (Exhibit 6-17, panel
A), although there was considerable regional variability
(Exhibit 6-18). The greatest increases came in the East
North Central climate region (11.2 percent per century)
and the South (10.5 percent). Hawaii was the only region
to show a decrease (-7.2 percent).
Indicator Limitations
• Biases may have occurred as a result of changes over time
in instrumentation, measuring procedures (e.g., time of
day), and the exposure and location of the instruments.
Where possible, data have been adjusted to account for
changes in these variables.
• Uncertainties in both the temperature and precipitation
data increase as one goes back in time, as there are fewer
stations early in the record. However, these uncertainties
are not sufficient to mislead the user about fundamental
trends in the data.
Data Sources
Anomaly data were provided by the National Oceanic and
Atmospheric Administration's (NOAA's) National Climatic
Data Center (NCDC), which calculated global, U.S., and
regional temperature and precipitation time series based
on monthly values from a net-work of long-term monitor-
ing stations (NOAA, 2007b). Data from individual stations
•were obtained from the U.S. Historical Climate Net-work
(USHCN version 1) and the Global Historical Climate
Network (GHCN), which are NCDC's online databases
(NOAA, 2007c).
EPA's 2008 Report on the Environment
6-33
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w*
INDICATOR
l.S. and Global Mean Temperature and Precipitation (continued)
Exhibit 6-16. Annual temperature anomalies in the U.S. by region, 1901-20063
A. Northeast
1901-2006 trend: +1.79°F per century
1900 1920 1940 1960 1980 2000
D. South
4 1901-2006 trend: +0.17T per century
3
2
1
0
-1
-2
-3
-4
-5
1900 1920 1940 1960 1980 2000
G. Southwest
1901-2006 trend: +1.69°F per century
1900 1920 1940 1960 1980 2000
J. Alaska
5 1918-2006 trend: +3.25°F per century
4
3
2
1
0
-1
-2
-3
-4
-5
1900 1920 1940 1960 1980 2000
B. Southeast
-5
1900 1920 1940 1960 1980 2000
E. East North Central
1901-2006 trend:
+1.76°Fper century!
4
3
2
1
0
-1
-2
-3
-4
-5
1900 1920 1940 1960 1980 2000
H. West
1900 1920 1940 1960 1980 2000
K. Hawaii
1905-2006 trend: +1.15°F per century
5
4
3
2
1
0
-1
-2
-3
-4
-5
1900 1920 1940 1960 1980 2000
Year
Anomalies are calculated with respect to the 1961-1990 mean.
bTime series were smoothed using a 9-point binomial filter.
Data source: NOAA, 2007b
— Annual anomaly
— Smoothed trendb
C. Central
1901-2006 trend: +0.24°F per century
1900 1920 1940 1960 1980 2000
F. West North Central
1901-2006 trend: +1.81°F per century
1900 1920 1940 1960 1980 2000
I. Northwest
1901-2006 trend: +2.1 1°F per century
1901-2006 trend: +1.73°F per century
1900 1920 1940 1960 1980 2000
Northwest
West
North Central
East
North Central
Central
Northeast
West
i
Southwest
Temperature change (°F per century):
-I
-3-2-10123
Gray interval:-0.1 to0.1°F
6-34
EPA's 2008 Report on the Environment
-------
INDICATOR
LS. and Global Mean Temperature and Precipitation (continued)
References
IPCC (Intergovernmental Panel on Climate Change).
2007. Climate change 2007: The physical science basis.
Contribution of Working Group I to the fourth assessment
report of the Intergovernmental Panel on Climate Change.
Cambridge, UK: Cambridge University Press.
NOAA. 2007a. 2006 annual climate review: U.S. sum-
mary. June 21, 2007, edition,
NOAA. 2007b. Data provided to ERG (an EPA contrac-
tor) by Jay Lawrimore and David Wuertz, NOAA. Octo-
ber 12-November 16, 2007.
NOAA. 2007c. National Climatic Data Center. Accessed
October-November 2007. (NCDC home page); (U.S.
Historical Climate Net-work version 1);
(Global Historical Climate Net-work)
Exhibit 6-17. Annual precipitation anomalies in
the contiguous U.S. and worldwide, 1901-20063
20
15
.>• 10
"re
I 5
I °
CD
1 -5
o.
-10
-15
-20
A. Contiguous U.S. precipitation anomalies
1901-2006 trend: +6.46% per century
Ul
TT r
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Year
B. Global precipitation anomalies
1901-2006 trend: +1.74% per century
L*v
,..,hj. t ,J
,.i, nT1'1
20
15
>• 10
re
I 5
I °
CD "3
Q_
-10
-15
-20
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Year
Anomalies and percent change are calculated with respect to the
1961-1990 mean.
Data source: NOAA, 2007b
EPA's 2008 Report on the Environment
6-35
-------
w*
INDICATOR
U.S. and Global Mean Temperature and Precipitation (continued)
Exhibit 6-18. Annual precipitation anomalies in the U.S. by region, 1901-20063
100
80
60
40
20
0
-20
-40
-60
A. Northeast
1901-2006 trend: +8.26% per century
1900 1920 1940 1960 1980 2000
100
80
60
40
20
0
-20
-40
-60
D. South
1901-2006 trend: +10.51% per century
1900 1920 1940 1960 1980 2000
100
80
60
40
20
0
-20
-40
-60
G. Southwest
1901-2006 trend: +1.28% per century
1900 1920 1940 1960 1980 2000
100
40
20
0
-20
-40
J. Alaska
1918-2006 trend: +5.92% per century
1900 1920 1940 1960 1980 2000
100
80
60
40
20
0
-20
-40
-60
B. Southeast
1901-2006 trend: +1.87% per century
1900 1920 1940 1960 1980 2000
E. East North Central
1901-2006 trend: +11.23% per century
100
80
60
40
20
0
-20
-40
-60
1900 1920 1940 1960 1980 2000
100
80
60
40
20
0
-20
-40
-60
H. West
1901-2006 trend:
+9.13% per century
1900 1920 1940 1960 1980 2000
100
80
60
40
20
0
-20
-40
-60
K. Hawaii
1905-2006 trend: -7.16% per century
1900 1920 1940 1960 1980 2000
Year
Anomalies and percent change are calculated with respect to the
1961-1990 mean.
bTime series were smoothed using a 9-point binomial filter.
Data source: NOAA, 2007b
— Annual anomaly
—Smoothed trendb
100
C. Central
1901-2006 trend: +8.13% per century
1900 1920 1940 1960 1980 2000
100
40
20
0
-20
-40
-60
F. West North Central
1901-2006 trend: +1.91% per century
1900 1920 1940 1960 1980 2000
100
I. Northwest
1901-2006 trend: +5.97% per century
1900 1920 1940 1960 1980 2000
Northwest
West
North Central
East
North Central
Central
Northeast
West
Southwest
Southeast
Hawaii
Change in precipitation (% per century):
I I
-35-28-21-14 -7 0 7 14 21 28 35
Gray interval: -2 to 2%
6-36
EPA's 2008 Report on the Environment
-------
INDICATOI
Sea Surface Temperature
Sea surface temperature (SST) is a critical
physical attribute of the oceans and coastal
ecological systems. Water temperature directly
affects biological and physical process rates,
•water column stability, and the presence and
functioning of species of plants (e.g., algae,
sea grasses, marsh plants, and mangroves) and
animals (e.g., microscopic animals, larger
invertebrates, fish, and mammals). Increases
in temperature have been associated with the
timing of breeding in sea turtles (Weisham-
pel et al., 2004), stress and bleaching of coral
reefs (Brown, 1997; Woodbridge and Done,
2004), alteration of species migration patterns,
changes in ecological system extent and com-
position (Helmuth et al., 2002), and changes in
the frequency or extent of blooms of harmful
algae (Ostrander et al., 2000). On longer time
scales (decades to centuries), rising SST may
result in decreases in the supply of nutrients
to surface waters from the deep sea, which could trigger a
cascade of effects leading to decreases in primary production
and declines in fish production (Pratchett et al., 2004), -wet-
land loss, reductions in coastal storm buffering, and losses of
local tourism. SST is both an indicator of, and a profound
influence on, the climate system. Changes in SST may result
from long-term cycles in ocean circulation, climate variabil-
ity, or secular trends in climate (Committee on the Bering
Sea Ecosystem et al., 1996).
This SST indicator, developed by the National Climatic
Data Center (NCDC) of the National Oceanic and Atmo-
spheric Administration (NOAA) and the National Center
for Atmospheric Research, describes the long-term vari-
ability and change in global mean SST for the 1880-2006
period. This reconstruction provides consistent spatial and
temporal data with their associated 95 percent confidence
intervals. The data are compiled from in situ measurements
from the International Comprehensive Ocean-Atmosphere
Data Set (ICOADS) release 2 (Slutz et al., 2002) and—in
recent years—from satellite imagery. Data are available
from multiple sources (e.g., ship reports, buoy monitors,
oceanographic profiles) from as early as 1854 (Woodruff
et al., 1998). By filtering and blending data sets that use
alternative measurement methods and include redundan-
cies in space and time, this reconstruction is able to fill
spatial and temporal data gaps and correct for biases in the
different measurement techniques (e.g., uninsulated buck-
ets, intakes near warm engines, uneven spatial coverage).
The extended reconstructed data are shown as anomalies,
or differences, from the "normal" (i.e., average) SST from
Exhibit 6-19. Annual global sea surface temperature anomaly,
1880-2006a
Lower 95% confidence interval
1900 1910 1920 1930
1940 1950
Year
1960 1970 1980 1990 2000
Coverage: Anomaly with respect to the 1971-2000 climate normal, which is plotted
as zero.
Data source: NOAA, 2007b
1971 to 2000. The long-term average change obtained by
this method is very similar to those of the "unanalyzed"
measurements and reconstructions developed by other
researchers (e.g., Rayner et al., 2003).
What the Data Show
The reconstruction of SST anomalies over all latitudes
indicates that the highest SSTs during the period of record
occurred over the last three decades (Exhibit 6-19). Warm-
ing has occurred through most of the twentieth century and
appears to be independent of measured inter-decadal and
short-term variability (Smith and Reynolds, 2005). The SST
•warming occurred in two parts, the first between 1910 and
1940 and the second after 1970, with a roughly stationary
period between 1940 and 1970. SST appears to have cooled
between 1880 and 1910, although confidence intervals are
•wider over the early period of record. Despite that uncer-
tainty, warming for the entire period of the indicator and for
the period from 1900 forward is statistically significant.
Indicator Limitations
• The 95 percent confidence interval is wider than other
methods for long-term reconstructions; in mean SSTs,
this interval tends to dampen anomalies.
• The geographic resolution is coarse for ecosystem
analyses but reflects long-term and global changes as
•well as variability.
• The reconstruction methods used to create this indicator
remove almost all random "noise" in the data. However,
the anomalies are also dampened when and where data
are too sparse for a reliable reconstruction. The 95 percent
EPA's 2008 Report on the Environment
6-37
-------
INDICATOR
Sea Surface Temperature (continued)
confidence interval reflects this "damping" effect as well as
uncertainty caused by possible biases in the observations.
• Data screening results in loss of many observations at lat-
itudes higher than 60 degrees north or south. Although
the effects of screening at high latitudes are extremely
small on the global average, the main effect is to lessen
anomalies and widen the confidence intervals.
Data Sources
This extended reconstruction of SST, called ERSST.v3,
\vas recently described in Smith et al. (in press). NCDC
(NOAA, 2007b) provides access to monthly and annual
SST and error data from this reconstruction (http://www.
ncdc.noaa.gov/oa/climate/research/sst/ersstv3.php), as well
as a mapping utility that allows the user to calculate average
anomalies over time and space (http://nomads.ncdc.noaa.
gov/#climatencdc). The ERSST.v3 reconstruction is based
on in situ measurements and satellite data, both of which
are available from online databases. In situ measurements
are available from NOAA (2007a) (http://icoads.noaa.gov/
products.html), and satellite data from NASA (2007) (http://
podaac.jpl.nasa.gov/DATA_PRODUCT/SST/mdex.html).
References
Brown, B. 1997. Coral bleaching: Causes and consequences.
Coral Reefs 16:5129-5138.
Committee on the Bering Sea Ecosystem, Polar Research
Board, Commission on Geosciences, Environment and
Resources, and National Research Council. 1996. The
Bering Sea ecosystem. Washington, DC: National Acad-
emies Press, pp. 196-237.
Helmuth, B., C.D.G. Harley, P.M. Halpm, M. O'Donnell,
G.E. Hofmann, and C.A. Blanchette. 2002. Climate
change and latitudinal patterns of intertidal thermal stress.
Science 298:1015-1017.
NASA (National Aeronautics and Space Administration).
2007. Physical Oceanography Distributed Active Archive
Center (PO.DAAC), sea surface temperature products. Jet
Propulsion Laboratory. Accessed 2007.
NOAA (National Oceanic and Atmospheric Adminis-
tration). 2007a. International Comprehensive Ocean-
Atmosphere Data Sets (ICOADS). Accessed 2007.
NOAA. 2007b. Sea surface temperature (SST) datasets.
National Climatic Data Center. Accessed October 2007.
Ostrander, G.K., K.M. Armstrong, E.T Knobbe, D. Gerace,
and E.P. Scully. 2000. Rapid transition in the structure
of a coral reef community: The effects of coral bleach-
ing and physical disturbance. Proc. Natl. Acad. Sci. USA
97(10):5297-5302.
Pratchett, M.S., S.K. Wilson, M.L. Berumen, and M.I.
McCormick. 2004. Sublethal effects of coral bleaching
on an obligate coral feeding butterflyfish. Coral Reefs
23(3):352-356.
Rayner, N.A., D.E. Parker, E.B. Horton, C.K. Folland,
L.V. Alexander, D.P. Rowell, E.G. Kent, and A. Kaplan.
2003. Global analyses of sea surface temperature, sea ice,
and night marine air temperature since the late nineteenth
century. J. Geophys. Res. 108:4407.
Slutz, R.J., SJ. Lubker, J.D. Hiscox, S.D. Woodruff, RL.
Jenne, D.H.Joseph, P.M. Steurer, and J.D. Elms. 2002.
Comprehensive ocean-atmosphere data set; release 1.
NTIS PB86-105723. Boulder, CO: NOAA Environmen-
tal Research Laboratories, Climate Research Program.
Smith, T.M., R.W. Reynolds, T.C. Peterson, andj.
Lawrimore. In press. Improvements to NOAA's Historical
Merged Land-Ocean Surface Temperature Analysis
(1880-2006). J. Climate,
(preprint)
Smith, T.M., and R.W. Reynolds. 2005. A global merged
land air and sea surface temperature reconstruction
based on historical observations (1880-1997). J. Climate
18(12):2021-2036.
WeishampelJ.E, D.A. Bagley, and L.M. Erhart. 2004.
Earlier nesting by loggerhead sea turtles following sea sur-
face warming. Glob. Change Biol. 10(8):1424-1427.
Woodbridge, S., and T Done. 2004. Learning to predict
large-scale coral bleaching from past events: A Bayesian
approach using remotely sensed data, in-situ data, and
environmental proxies. Coral Reefs 23(1):96-108.
Woodruff, S.D., H.F. Diaz, J.D. Elms, and SJ. Worley.
1998. COADS release 2 data and metadata enhancements
for improvements of marine surface flux fields. Phys.
Chem. Earth 23(5-6):517-526.
6-38
EPA's 2008 Report on the Environment
-------
Sea Level
Sea level is an indicator of global and local change and
a factor that affects human welfare and coastal ecosys-
tem conditions. Coastal areas host a rich set of natural and
economic resources and include some of the most developed
and rapidly growing population centers in the nation. More
than 100 million people globally live within 1 meter of the
mean sea level and more than 40 percent of the U.S. popula-
tion lives in -watersheds along U.S. ocean coasts (NOAA,
2005). Changing sea levels can inundate low-lying wetlands
and dry lands (Burkett et al, 2005), erode beaches (USGS,
1998), change rates of sedimentation (Olffet al., 1997),
and increase the salinity of marshes, estuaries, and aquifers
(Condrey et al., 1995; Williams et al., 1999). Documented
consequences of sea level rise include loss of buffering
against storms and floods (Burkett et al., 2005), changes in
bird populations (Erwin, 2005) and land cover (Williams et
al., 1999), property losses (Burkett et al., 2005), and infra-
structure damage (Theilerand Hammar-Klose, 1999; U.S.
Department of Transportation, 2003).
Approximately 58,000 square kilometers of land in the
contiguous U.S. lie less than 1.5 meters above sea level;
80 percent of this land is in Louisiana, Florida, Texas,
and North Carolina (Titus and Richman, 2001). Almost
half of the shoreline studied along the U.S. Atlantic Coast
\vas determined to be highly to very highly vulnerable
to effects of sea level rise (Theiler and Hammar-Klose,
1999). The areas of highest vulnerability are high-energy
coastlines where the coastal slope is low and the major
landform type is a barrier island. The risks may be mini-
mal if \vetlands accretion can match or outpace sea level
rises, but accretion rates vary -widely (Hartig et al., 2000,
Table 3).
A number of factors affect sea level, including, but not
limited to, changes in sea temperature, salinity, and total
•water volume and mass (e.g., from melting glaciers or
changes in the amount of water stored on land). Sea level
rises with warming sea temperatures and falls with cool-
ing. Changes in the total volume and mass of ocean water
also result from the melting or accumulation of Antarc-
tic and Greenland ice sheets and non-polar glaciers and
changes in the amount of water stored in lakes, rivers, and
ground water. As such, global average sea level change is
Exhibit 6-20. Changes in relative sea level along U.S. coasts, 1950-1999a
75°N
60°N -
45°N -
30°N -
15°N
165°W
150°W
135°W
120°W
105°W
90°W
75°W
60°W
aTrends are based on tidal gauge measurements. Each dot represents a tidal gauge
station that operated during the period 1950-1999.
Data source: NOAA, 2006
Mean relative sea level change (mm per year):
o-18to-15 o-5.99to-3 o 3.01 to 6
o-14.99to-12 o-2.99toO o 6.01 to 9
• -11.99to-9 o 0.01(03 • 9.01to12
• -8.99(0-6
EPA's 2008 Report on the Environment
6-39
-------
w*
INDICATOR
Sea Level
(continued)
an indicator of the physical and climatic stability of the
global environment.
Temporal scale is an important factor in interpreting sea
level trends. Sea level changes may reflect factors such as
seasonality, inter-annual to decadal scale variability such
as El Nino, and/or long-term climate change (decades to
centuries). Spatial scale also is important because absolute
sea height does not change uniformly around the globe.
This indicator presents trends in absolute and relative
sea level. Absolute sea level represents only the sea height,
\vhereas relative sea level change is defined as sea height
change plus land height changes (due to subsidence or
uplift and changes in natural land accretion). Relative sea
level data are from the tidal gauge measurements of the
National Water Level Observation Net-work, composed
of approximately 175 long-term, continuously operat-
ing stations located along the U.S. coast, including the
Great Lakes and islands in the Atlantic and Pacific Oceans
(Smith, 1980; Gill and Schultz, 2001). Tidal gauge data
are presented from 1950 to 1999, although a few loca-
tions have been monitoring since the mid-1800s (NOAA,
2001). Absolute sea level data are from satellite measure-
ments from NASA's TOPEX/Poseidon spacecraft, which
uses radar to map the precise features of the ocean surface,
and the "Jason" satellite, which monitors ocean circulation
(Leuliette et al., 2006). The two satellites use radar altim-
etry to collect sea level data globally. These data have been
available since 1993.
What the Data Show
Relative sea levels (combined land and sea movement) in
many locations rose from 1950 to 1999, typically at rates
of 0-3 millimeters per year (mm/yr) (up to 1 foot per cen-
tury) (Exhibit 6-20). Relative sea level has risen more rap-
idly (3-6 mm/yr) along the mid-Atlantic coast from North
Carolina to New Jersey and at rates as high as 9-12 mm/
yr at two stations in Louisiana. Other locations, such as the
southern coast of Alaska, show relative sea level drop, with
a maximum decrease of 16 mm/yr. Average relative sea
level rise for all U.S. coasts was not calculated because the
distribution of tidal gauge stations is not spatially repre-
sentative of aggregate trends, but for reference, an analysis
of tidal gauge data worldwide estimated that on average,
relative sea level rose between 1.5 and 2.0 mm/yr during
the 20th century (Miller and Douglas, 2004).
The satellite record shows that global mean absolute sea
level (i.e., independent of land movements) has increased
at a rate of 3 mm (0.12 inches) per year since 1993 (Exhibit
6-21). Absolute sea levels do not change uniformly around
the Earth, however. Around the U.S., areas with increas-
ing absolute sea level include the Gulf coast and portions of
the Atlantic coast (Exhibit 6-22). Areas showing a decrease
include the southern part of the Pacific coast and the -west-
ern Gulf of Alaska.
Exhibit 6-21. Global mean sea level, 1993-20063
40
30
— 20
-10
-20
Trend: +3.0 mm per year
1992 1994 1996 1998 2000 2002 2004
Year
2006
TOPEX measurements
Jason measurements
60-day smoothing
aValues are reported as anomalies with
respect to the 1993-1997 mean.
bData were collected by the
TOPEX/Poseidon and Jason 1 satellite
altimeters. Data were adjusted by
applying an inverse barometer (air pressure) correction and removing
seasonal signals.
Data source: Leuliette et al., 2006
Indicator Limitations
• An estimated 50 to 60 years of data are required to
obtain linear mean sea level trends having a 1 mm/yr
precision -with a 95 percent statistical confidence interval.
• Tidal gauge measurements do not represent more gener-
alized (i.e., average) relative sea level change along U.S.
coasts (or globally).
• Most local tidal gauge measurements cannot indicate
•whether changes in relative sea level are due to changes
in absolute sea level or changes in land elevation.
• Satellite data are not available for a multi-decadal time
series needed to separate out medium-term variability
from long-term change.
• Satellite data are not horizontally precise enough to
resolve sea level trends for small water bodies (such as
many estuaries) or for localized interests (such as a par-
ticular harbor or beach).
Data Sources
Exhibit 6-20 is based on a map and corresponding trend
data published by the National Oceanic and Atmospheric
Administration's (NOAA's) National Oceans Service
(NOAA, 2006) (http://tidesandcurrents.noaa.gov/sltrends/
sltrends.shtml). These data were previously published in
6-40
EPA's 2008 Report on the Environment
-------
Sea Level
(continued)
Exhibit 6-22. Changes in absolute sea level along U.S. coasts, 1993-20063
75°N
60°N -
165°W
150°W
135°W
120°W
105°W
aTrends are based on satellite measurements. Data were adjusted by
applying an inverse barometer (air pressure) correction.
Data source: Leuliette et al, 2006
90°W 75°W 60°W
Mean absolute sea level change (mm per year):
No data -15 -10 -5 0 5 10 15
NOAA (2001), along with a list of station coordinates
(NOAA, 2001, Appendix I). Individual station measure-
ments are accessible through NOAA (2006).
Exhibits 6-21 and 6-22 were produced using data pro-
vided by Leuliette et al. (2006) (time series at http://sealevel.
colorado.edu/results.php; map at http://sealevel.colorado.
edu/maps.php). Leuliette et al.'s analysis was based on mea-
surements from NASA's Ocean Topography Experiment
(TOPEX) and Jason satellite altimeters; results were cali-
brated using a model documented in Leuliette et al. (2004).
Satellite measurements can be obtained from NASA's online
database (NASA, 2006) (http://topex-www.jpl.nasa.gov/
science/data.html).
References
Burkett, V.R., D.B. Zilkoski, and D.A. Hart. 2005. Sea-
level rise and subsidence: Implications for flooding in New
Orleans, Louisiana. In: Subsidence observations based on
traditional geodetic techniques, and numerical models. U.S.
Geological Survey, National Wetlands Research Center.
Condrey, R., P. Kemp, J. Visser, J. Gosselink, D. Lindstedt,
E. Melancon, G. Peterson, and B. Thompson. 1995. Status,
trends, and probable causes of change in living resources in
the Barataria and Terrebonne estuarine systems. Thibodaux,
LA: Barataria-Terrebonne National Estuary Program.
Erwin, R.M. 2005. Atlantic sea level rise, lagoonal marsh
loss, and wildlife habitat implications. U.S. Geological
Survey. Accessed December 29, 2005.
Gill, S.K., and J.R. Schultz. 2001. Tidal datums and
their applications. NOAA Special Publication NOS
CO-OPS 1.
Hartig, E.K., F. Mushacke, D. Fallon, and A. Kolker.
2000. A wetlands climate change impact assessment for the
metropolitan East Coast region. Draft for public review.
Leuliette, E.W., R.S. Nerem, G.T. Mitchum, and D.P.
Chambers. 2006. Sea level change: 2006 release #3.
Accessed October 2006.
Leuliette, E.W., R.S. Nerem, and G.T. Mitchum. 2004.
Calibration of TOPEX/Poseidon and Jason altimeter data
to construct a continuous record of mean sea level change.
Mar. Geod. 27(l-2):79-94.
EPA's 2008 Report on the Environment
-------
INDICATOR
Sea Level
(continued)
Miller, L., and B.C. Douglas. 2004. Mass and volume
contributions to twentieth-century global sea level rise.
Nature 428:406-409.
NASA (National Aeronautics and Space Administration).
2006. Ocean surface topography from space. Updated
January 2006.
NOAA (National Oceanic and Atmospheric Administra-
tion). 2006. Sea levels online. Accessed October 6, 2006.
(home page); (data table)
NOAA. 2005. Population trends along the coastal United
States: 1980-2008.
NOAA. 2001. Sea level variations of the United States
1854-1999. NOAA Technical Report NOS CO-OPS 36.
Olff, H., J. De Leeuw, J.P. Bakker, RJ. Platermk, HJ. Van
Wijnen, and W. De Munck. 1997. Vegetation succession
and herbivory in a salt marsh: Changes induced by sea level
rise and silt deposition along an elevational gradient. J.
Ecol. 85:799-814.
Smith, R.A. 1980. Golden Gate tidal measurements. J.
Waterw. Port C. Div. 106(WW3):407-410.
Thieler, E.R., andE.S. Hammar-Klose. 1999. National
assessment of coastal vulnerability to sea-level rise: prelim-
inary results for the U.S. Atlantic coast. U.S. Geological
Survey Open-File Report 99-593.
Titus, J., and C. Richman. 2001. Maps of lands vulnerable
to sea level rise: modeled elevations along the U.S. Atlantic
and Gulf coasts. Climate Res. 18:205-228.
U.S. Department of Transportation. 2003. Does sea level
rise matter to transportation along the Atlantic coast? In:
U.S. Department of Transportation, Center for Climate
Change and Environmental Forecasting. The potential
impacts of climate change on transportation.
USGS (United States Geological Survey). 1998. The
Chesapeake Bay: Geologic product of rising sea level. Fact
Sheet 102-98.
Williams, K., K.C. Ewel, R.P. Stumpf, F.E. Putz, and T.W.
Workman. 1999. Sea-level rise and coastal forest retreat on
the west coast of Florida, USA. Ecology 80(6):2045-2063.
6.5.3 Discussion
What These Indicators Say About Trends in
Critical Physical and Chemical Attributes of
the Nation's Ecological Systems
Critical Physical Attributes
Information is available on trends in temperature and pre-
cipitation (see the Temperature and Precipitation indicator,
p. 6-32). Across the contiguous U.S., mean temperature
increased over the past century. The rate of increase in the past
30 years was higher than in the previous part of the century,
amounting to more than 0.5°F per decade. Some regional
trends in temperature are evident, with Alaska and the -west-
ern part of the contiguous 48 states exhibiting a greater-warm-
ing trend than the rest of the country. This overall -warming
trend is consistent -with the latest findings of the Intergovern-
mental Panel on Climate Change (IPCC), -which concluded
that "Warming of the climate system is unequivocal, as is now
evident from observations of increases in global average air
and ocean temperatures, -widespread melting of snow and ice,
and rising global average sea level."38
These general -warming trends have occurred concurrently
•with rising atmospheric concentrations of greenhouse gases
(see the Greenhouse Gas Concentrations indicator, p. 2-66).
The IPCC confirms a connection, concluding that "Most of
the observed increase in global average temperatures since the
mid-20th century is very likely [defined by IPCC as greater
than 90 percent probability] due to the observed increase in
anthropogenic greenhouse gas concentrations."39
Temperature changes can influence the physical aspects of
ecological systems, including regional and global -weather and
oceanographic patterns. Observed impacts associated -with
•warming include the global retreat of mountain glaciers,
reduction in snow-cover extent, earlier spring melting of ice
on rivers and lakes, and increases in sea surface temperatures
Intergovernmental Panel on Climate Change. 2007. Climate change 2007:
The physical science basis. Contribution ofWorking Group I to the fourth
assessment report of the Intergovernmental Panel on Climate Change.
Cambridge, UK: Cambridge University Press,
Ibid.
6-42
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and ocean heat content.40 For example, global sea surface
temperature increased throughout the past century, with the
greatest increases occurring in the past three decades (see the
Sea Surface Temperature indicator, p. 6-37).
The potential ecological implications of a gradual warming
trend have received much attention.41'42'43 Virtually every eco-
logical system in the U.S. is potentially vulnerable to changes
in temperature regimes that might affect physical (and in turn,
biological) conditions, including coastal and marine areas,44'45
inland freshwater and wetland systems,46 and terrestrial sys-
tems.47 All species have preferred ranges of temperature for
survival, growth, and reproduction as well as lower and upper
thermal tolerance limits. Mean temperature, seasonal changes,
and other temporal fluctuations constitute species' temperature
regimes. As these regimes change, several types of stresses are
placed on a species. First, a species may not be well adapted
to the new regime and may not be able to sustain its popula-
tion. Second, other species may be better adapted and able to
extend their ranges into new areas. Finally, because tem-
perature can affect other biological and physical attributes of
systems, the ecological system itself may change in a way that
is not favorable for the species.
Temperature patterns are interlinked with air and water cir-
culation patterns, which are critical to the dispersal of organ-
isms, the movement of nutrients, and many other processes
important to sustaining ecological systems. The replenish-
ment of water over land surfaces is particularly critical, as it
is a major determinant of the sustainability of the varied eco-
logical systems that exist along a gradient of moisture from
•wetlands to deserts. For example, in areas where precipita-
tion is reduced, droughts can have a pronounced and rapid
influence on vegetation.48
Overall, precipitation increased in the U.S. over the past
century (see the Temperature and Precipitation indicator, p.
6-32). Regional differences are apparent, however, with the
greatest increases in the East North Central climate region and
the South, very small increases in other regions, and a decrease
in Hawaii. It is difficult to assign causes to such local and
regional changes in precipitation because of natural climate
variability (e.g., oscillations such as El Nino and others), com-
plex interactions between aerosols (from natural and industrial
processes) and clouds, and the effects of urban and rural land
use on evaporation and transpiration.
Stream flows are another physical attribute that shapes and
sustains ecological systems. Whether by moving sediment
under high flow regimes or fostering sedimentation in lower
flow regimes, stream flows impact ecological communities
by forming aquatic habitats and defining habitat boundaries.
Streambed stability is an important variable in this regard (see
the Streambed Stability indicator, p. 3-11). Cycles of high and
low flow are particularly important for species that depend on
specific conditions. For example, streambeds may require an
annual high flow event to restore habitat that had been filled
•with debris and sediment during lower flow periods. The
timing of seasonal flows also coincides with the reproductive
cycles of some species. Data from stream gauges indicate that
over the last half-century, high flow volumes have increased
substantially in many streams compared to the previous 20
years, but they have decreased in just as many (see the Stream
Flows indicator, p. 3-8). Mean-while, low flow volume appears
to have increased in many streams, while variability of flow
has generally decreased—indicating a smaller difference
between high and low flows. Among streams in grassland and
shrubland areas, the number and duration of no-flow periods
also has decreased since the 1960s. While weather patterns
naturally vary from year to year, trends revealing broader
shifts in high and low flows and changes in no-flow periods
may fore-warn of instability in ecological systems.
In many locations along the U.S. coast, sea level has risen
steadily, reflecting changes in -water levels as -well as subsid-
ence in land in some areas (see the Sea Level indicator, p.
6-39). These changes can alter the ecological conditions in
coastal areas, especially -where land elevations are low. The
rise of sea levels results in increased flooding that can be
exacerbated during storm events. Rising sea level also can
result in increased salinity levels in coastal inland -waters and
soils, thereby changing the chemical condition of habitats.
Fresh-water ecological systems are progressively lost as they
are transformed into more saline inland -waters or into open
coastal -waters.
Critical Chemical Attributes
Dissolved oxygen is critical to the support of aerobic animals
and plants. In aquatic systems, dissolved oxygen levels reflect a
balance between that produced by plants, consumption by all
biota, and physical mixing processes. The spatial extent and
timing of reduced oxygen conditions (hypoxia) and no oxygen
40 Intergovernmental Panel on Climate Change. 2007. Climate change 2007:
Impacts, adaptation and vulnerability. Contribution ofWorking Group II
to the fourth assessment report of the Intergovernmental Panel on Climate
Change. Cambridge, UK: Cambridge University Press,
41 National Research Council. 2001. Climate change science:An analysis of
some key questions. Committee on the Science of Climate Change. Washing-
ton, DC: National Academies Press.
42 Millennium Ecosystem Assessment Board. 2005. Living beyond our means:
Natural assets and human well being,
43 Intergovernmental Panel on Climate Change. 2007. Climate change 2007:
Impacts, adaptation and vulnerability. Contribution ofWorking Group II
to the fourth assessment report of the Intergovernmental Panel on Climate
Change. Cambridge, UK: Cambridge University Press,
44 Barry, J.R, C.H. Baxter, R.D. Sagarin, and S.E. Gilman. 1995. Climate-related,
long-term fauna! changes in a California rocky intertidal community. Science
267:672-675.
45 KennedyVS., R.R.Twilley J.A. Kleypas, J.H. Cowan, Jr., and S.R. Hare. 2002.
Coastal and marine ecosystems and global climate change: Potential effects on
U.S. resources. Arlington,VA: Pew Center on Global Climate Change.
46 Poff, N.L., M.M. Brinson, and J.W Day, Jr. 2002. Aquatic ecosystems and
global climate change: Potential impacts on inland freshwater and coastal wet-
land ecosystems in the United States. Arlington,VA: Pew Center on Global
Climate Change.
47 Malcolm, J., and L. Pitelka, 2000. Ecosystems and global climate change: A
review of potential impacts on U.S. terrestrial ecosystems and biodiversity.
Washington, DC: Pew Center on Global Climate Change.
48 Allen, C., and D. Breshears. 1998. Drought-induced shift of a forest-
woodland ecotone: Rapid landscape response to climate variation. PNAS
95(25):1483 9-14842.
EPA's 2008 Report on the Environment
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conditions (anoxia) affects the distribution and sustainability
of populations of aerobic organisms. As hypoxic and anoxic
areas increase in size and persistence, animals such as mollusks
(snails and clams), arthropods (e.g., crabs and shrimp), and fish
have proportionally less habitat within which they can thrive.
For these reasons, trends in oxygen affects the sustainability of
populations as well as the overall biodiversity of aquatic and
marine systems.
Regional information is available on hypoxic conditions in
the Gulf of Mexico and Long Island Sound (see the Hypoxia
in Gulf of Mexico and Long Island Sound indicator, p. 3-48).
The size of the hypoxic zones in both the Gulf of Mexico
and Long Island Sound has been highly variable since the
mid-1980s, with no discernable trend in either area. In both
cases, there remain substantial areas in the latest year of record
(2007) where low dissolved oxygen concentrations make the
•waters unsuitable to support most fish and shellfish species.
Nutrient levels are tightly interwoven into ecological con-
dition. Aquatic systems are strongly influenced by nutrient
levels, and nutrient inputs within a -watershed may impact
ecological systems far from the origin of the input (e.g., input
occurs upstream, but impact occurs at the mouth of a river).
Indicators focusing on the most active nutrients in aquatic
systems—nitrogen and phosphorus—provide insights into
trends in nutrient loads, cycles, and transport.
Nutrient loads have been examined for the Mississippi,
Columbia, St. Lawrence, and Susquehanna Rivers (see the N
and P Loads in Large Rivers indicator, p. 3-17). The largest
of the monitored rivers, the Mississippi River, carries more
than 15 times the nitrate load of the other rivers. The nutrient
loads in this river more than doubled from the 1950s to the
present. In contrast to the overall upward trend of nitrate loads
in the Mississippi River, nitrate loads in the Columbia River
nearly doubled in the 1990s compared to historical loads, but
returned to historical levels by 2002. Nitrate loads increased in
the St. Lawrence but did not exhibit a particular trend in the
Susquehanna. Trends in phosphorus loads are variable in the
Mississippi and Columbia Rivers, and show a decrease in the
St. Lawrence and Susquehanna Rivers, likely due to phospho-
rus controls.
Baseline information on nitrogen and phosphorus concentra-
tions is available for two sets of streams: wadeable streams
and streams in agricultural -watersheds. Among wadeable
streams, a recent nation-wide survey found that for both
of these nutrients, roughly one-third of wadeable stream
miles had concentrations that -were substantially higher than
regionally appropriate reference levels (see the N and P in
Wadeable Streams indicator, p. 3-13). Agriculture-dominated
•watersheds are often characterized by higher loads of applied
nitrogen and phosphorus fertilizers to optimize crop develop-
ment. Streams located -within these areas provide an indica-
tion of the extent of nutrient inputs. Baseline studies confirm
that levels of nitrogen and phosphorus are elevated in many of
these -water bodies (see the N and P in Agricultural Streams
indicator, p. 3-19).
The pH of air masses and -waters is critical to biological func-
tions, can directly affect the viability of species, and can affect
the bioavailability of chemicals (both nutrients and potential
toxics). There has been a decrease in wet deposition of sulfur
and nitrogen compounds over the past 15 years, as discussed
in Chapter 2. Associated -with the decrease in deposition has
been an increase in the acid neutralizing capability of-water
bodies (see the Lake and Stream Acidity indicator, p. 2-42).
In one sensitive region, however (the Blue Ridge), fresh -water
bodies have yet to show recovery from acidification.
Limitations, Gaps, and Challenges
There are ROE indicators for only a few of the critical
physical and chemical attributes of ecological systems. EPA
•would like to have ROE indicators for solar radiation over
land and -water as -well as penetration into the nation's -waters.
In addition, there are no ROE indicators of disturbance
regimes associated -with flooding and fire. Other important
gaps include -water levels in lakes, the amount of snowpack
or ground -water available to support base flow in rivers and
streams, and indicators of soil quality such as salinity or base
cation saturation. Still, information is available for a few of
the most critical attributes. Trends in temperature provide
insight into other trends that have important biological and
physical ramifications.
The indicators of trends in chemical and physical life-sustaining
parameters are influenced by uncertainty. As technology
changes, biases develop for data collected over long periods of
time. Data collection tools may improve, creating new uncer-
tainties -when comparing recent data to historical trend data.
In historical trend analyses, gaps in the record may emerge.
Bridging the gaps between data series may require use of esti-
mation or interpolation methods, or those time periods may
be excluded altogether. All indicators of long-term trends are
susceptible to changes in monitoring technology and historical
data gaps. However, the increase in temperature and precipita-
tion is occurring, and -with the collection of additional data sets,
longer-term trends can be confirmed or refuted.
Measuring trends in physical and chemical attributes is subject
to a number of limitations. For the assessment of the indicator
for stream flow, the U.S. Geological Survey gauging stations
that generate the data for this parameter are placed on the
larger tributaries and may miss trends in the smaller water-
ways. However, this indicator does provide valuable trend
information regarding high and low flows for larger water-
ways. For the assessment of acidification, the focus is largely
on areas -where previous studies revealed an impact. This may
exclude areas that are impacted to a lesser extent by acid rain.
While the large river surveys provide trend data for a -water-
shed, it is not possible to identify the relative contributions
of different land uses in the river basin. More detailed studies
focus on the most common land uses contributing to nutrient
runoff. Each provides useful information regarding trends in
the specific system.
Information contained in the indicators represents baseline,
decadal, and even century-level trends. However, for hydro-
logic and temperature patterns, these time periods may be
too short to assess long-term changes. The field of paleocli-
matology offers some promise for extending information to
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larger time frames.49 In addition, the predictive capability of
forecasting the extent of dissolved oxygen deficits in regional
and coastal water bodies is increasing.50 Information is also
available on the distribution of solar energy over the surface of
the U.S. Over time, such information could be used to evalu-
ate trends in this physical attribute.
6.6 What Are the
Trends in Biomarkers
of Exposure to
Common Environmental
Contaminants in Plants
and Animals?
6.6.1 Introduction
Chemicals can be introduced to the environment intentionally
(e.g., fertilizers, pesticides, and herbicides), or unintentionally
through accidental spillage or leaks of chemicals used in home
and commercial applications (e.g., in wastes from municipal
and industrial operations). The extent to which the presence
of mixtures of chemicals influences human health and the
environment has long been a focus of EPA assessments.
Biomarkers of exposure can include measures of chemical
concentrations in plant and animal tissue. Such measures
provide insight into the magnitude of chemical exposure
that organisms receive from their environment. Measures of
biological response such as biochemical concentrations (e.g.,
enzymes and ligands) that respond to chemical exposures
can also serve as biomarkers of exposure. Examples include
histopathological anomalies such as plant tissue damage from
ozone or tumors in fish exposed to sediment contaminated
•with polycyclic aromatic hydrocarbons (PAHs). This evalua-
tion examines the trends in biomarkers of exposures to com-
mon environmental contaminants in plants and animals as
presented in the ROE indicators. It also discusses challenges
in assessing trends in these biomarkers.
Chemical stressors can have a detrimental effect on plant
and animal communities. Exposure of plants and animals to
chemical stressors can lead to increases in tissue concentra-
tions of the chemical stressor in the plants and animals. Once
stressor concentrations are above threshold levels, they can
affect physiological systems within the plants and animals
National Oceanic and Atmospheric Administration. 2003. North American
drought:A paleo perspective,
Longstaff, B.J., D.Jasinski, and P.Tango. 2005. Ecological forecast—summer
2005. Monitoring and Analysis Subcommittee. Chesapeake Update.
U.S. Environmental Protection Agency. 2002. EMAP research strategy.
EPA/620/R-02/002.
and can begin to have toxic effects on individuals within
the population. These individual effects can lead to changes
in plant and animal community structure when chemi-
cal stressor concentrations in the environment reach levels
that can affect one or more species, or when the population
numbers of a key species are detrimentally affected. Bio-
markers of exposure, including concentrations of chemical
stressors or key biomarkers collected over time within plant
and animal tissues, can help to gauge the health of plant and
animal communities over time. These biomarkers of chemi-
cal exposure, when coupled with other information (e.g.,
toxicity testing results), can provide a basis for estimating
•what levels of a chemical stress can and cannot be tolerated
in the environment by plant and animal communities. These
biomarkers also help explain the recovery of certain ani-
mal populations (e.g., brown pelican) that were once nearly
driven to extinction by specific chemical stressors. Tissue
levels of pesticides, PCBs, and mercury have been used
for many years to evaluate exposures to such species as the
brown pelican, bald eagle, and lake trout and a host of other
fish and wildlife. The Mussel Watch program relies on sam-
pling lower-trophic-level organisms (mussels and clams) for
a broad range of chemicals to evaluate exposures in coastal
areas. As these examples demonstrate, measures of bioaccu-
mulative compounds in animal tissues provide an indication
of exposure levels throughout food webs.
6.6.2 ROE Indicators
Although trends in specific contaminants of concern in
environmental media (e.g., sediments or air) have been avail-
able for specific locations, the indicators to evaluate trends in
biomarkers of exposure to common environmental contami-
nants in plants and animals are mainly focused on national or
regional programs that have been measuring chemical stressor
concentrations in fish tissue in lakes and coastal regions of the
U.S. over less than a decade. An example of such biomoni-
toring efforts is summarized in the National Coastal Con-
dition Report II,51 \vhich was completed as a collaborative
effort between EPA, the National Oceanic and Atmospheric
Administration, the U.S. Fish and Wildlife Service, and the
U.S. Geological Survey.52
Trends in biomarkers of exposure to common environmental
contaminants in plants and animals are evaluated using three
National Indicators (Table 6-6). The focus of this question is
on national- or regional-scale trends in biomarkers of expo-
sure over the period in which measurements have occurred
(i.e., the last one to three decades, depending upon the bio-
markers of exposure). While other subregional or local-scale
efforts concerning monitoring of biomarkers of exposure can-
not be covered here, they are no less important.
52 Within the U.S. Geological Survey the Biomonitoring of Environmental
Status and Trends (BEST) Program is another example of a national program
mandated to collect biomarkers of common contaminant exposure. Although
monitoring offish contaminant concentrations is a focus of this program, this
program also monitors common pollutants in many other aquatic and terres-
trial receptors, such as upper trophic level receptors (fish-eating birds like the
bald eagle), and catalogues biomarker data collected from many sources into
an online database.
EPA's 2008 Report on the Environment
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Table 6-6. ROE Indicators of Trends in Biomarkers of Exposure to
Common Environmental Contaminants in Plants and Animals
National Indicators
Coastal Fish Tissue Contaminants (N/R)
Contaminants in Lake Fish Tissue
Ozone Injury to Forest Plants
Section
3.8.2
3.8.2
2.2.2
3-61
3-63
2-24
N/R = National Indicator displayed at EPA Regional scale
6.6.3 Discussion
What These Indicators Say About Trends
in Biomarkers of Exposure to Common
Environmental Contaminants in Plants
and Animals
The ROE indicators provide a baseline of recent conditions
against which future trends can be assessed. Lipophilic chemi-
cals such as polychlorinated biphenyls (PCBs), DDT, and
methylmercury are present in fish tissues throughout most of
the nation's freshwater lakes and coastal systems (Coastal Fish
Tissue indicator, p. 3-61; Lake Fish Tissue indicator, p. 3-63),
•which shows -widespread exposure to these bioaccumulative
compounds. Some judgment concerning these levels can be
made by reference to benchmarks that relate to tissue residues.
For example, approximately one-fifth of estuarine fish samples
•were found to have at least one contaminant at levels that
exceed commonly used benchmarks. Differences are apparent
across EPA Regions. The contaminants most responsible for
exceedances were PCBs, mercury, DDT, and PAHs.
Foliar injury from ozone pollution disrupts plant/tree physiol-
ogy. Baseline data indicate that exposure of forests to ozone
levels varies geographically, with more severe injury generally
occurring in the eastern U.S. than in the West (Ozone Injury
to Forest Plants indicator, p. 2-24). Up to 7 percent of sites
had severe foliar injury in some EPA Regions, while no injury
•was observed at sites in Regions 8 and 10.
Limitations, Gaps, and Challenges
Few national programs involve unbiased assessment that
can support indicators of trends in national conditions in
biomarkers of exposure. While there are tissue-level ROE
indicators for fish, there are no similar indicators for plants
(either aquatic or terrestrial) or wildlife species. This repre-
sents a gap in EPA's ability to identify trends in biomarkers of
exposure to common environmental contaminants in plants
and animals.
Among the primary challenges relating to monitoring bio-
markers of exposure are the following:
• To monitor a single biomarker of exposure on a national or
regional scale requires a great deal of planning, coordina-
tion, and resources. Biomarkers are more costly and time-
consuming to measure than chemical concentrations in
other media (e.g., water, sediment, air), because the living
things that require measurement are more difficult to col-
lect and/or analyze for the chemical stressors.
• The biomarkers of exposure need to be clearly linked to
biomarkers of effects to be useful for predicting whether the
function of plant or animal communities is being affected
by the concentrations of chemical in the environment. In
many cases, capabilities are currently lacking to link bio-
markers of exposure with biomarkers of effects. In addition,
most monitoring focuses on the media within which plants
and animals live (i.e., air and water), and does not address
the body burden of the chemical in the plant or animal or
biomarkers of effects.
• With a myriad of environmental contaminants in the
environment, it is difficult to prioritize which contaminants
should be monitored in biological tissues. Classically, the
organochlorine pesticides (e.g., DDT), PCBs, and mercury
have been monitored in fish tissues in the aquatic environ-
ment. However, in the future, new chemicals may emerge
as equally or more important (see Chapter 7).
6-46
EPA's 2008 Report on the Environment
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7. Afterword
Next Steps
The Report on the Environment represents a commitment by
EPA to continually improve the quality and quantity of infor-
mation available to understand the condition of human health
and the environment and how they are changing over time.
The results of these improvements will be communicated to
the public via regular updates of the ROE. Specific plans for
updating the report include:
• EPA's 2008 ROE: Revised editions of this report will
be produced at a frequency that will provide input to the
Agency's strategic planning process. New editions will
reflect revisions or additions to the ROE questions, updates
and revisions of the indicators in this report, addition of
new indicators, and revisions to the "Introduction" and
"Discussion" sections that accompany each question.
• EPA's 2008 ROE: Highlights of National Trends: This
document, which communicates key information from the
ROE to the interested public, will be updated periodically.
• Electronic version of the ROE (http://www.epa.
gov/roe): EPA will present the ROE and ROE High-
lights in electronic form on the Internet so people can
navigate and query the ROE content. This "e-ROE" will
be updated on an ongoing basis to enable users to obtain
indicator revisions as soon as they are available.
To strengthen its ability to answer the ROE questions, the
Agency will work to overcome some of the important chal-
lenges identified by public comments and by EPA's Science
Advisory Board in its review of the 2008 ROE.
EPA's 2008 Report on the Environment
7-1
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Challenges
Throughout this report, EPA uses indicators to answer what
it believes are among the most important questions about the
environment and human health. For many of these questions,
the answers are incomplete. Three important challenges affect
EPA's ability to answer these questions:
• Synthesizing and integrating information from multiple
indicators to obtain a coherent understanding of their
interrelationships, as relevant to the ROE questions.
• Filling gaps and reducing limitations in the 2008 ROE
indicators.
• Addressing emerging issues that suggest potential new areas
of concern for which indicators are not yet available.
All three areas offer opportunities for improvement in future
editions of this report.
Synthesis and Integration
Synthesizing and integrating information across multiple
indicators is a major challenge for several reasons:
• There currently are no "meta-indicators" that can provide
an integrated, comprehensive measure of trends in human
health or the environment to answer any of the ROE
questions. Instead, the available indicators provide in-depth
coverage of particular aspects of the environment or health
that are relevant to answer the questions.
• Differences in the spatial and temporal coverage of indicator
data make it difficult to compare trends among indicators.
• In many cases, it is not clear whether a trend in one ROE
indicator is directly linked to trends in other, potentially
related ROE indicators.
These types of challenges preclude EPA from being able, at
present, to fully respond to the individual ROE questions or
to make an integrated or "bottom line" statement in response
to any of the questions. EPA will strive to address these chal-
lenges in future reports by working to fill gaps and reduce
indicator limitations, as described below.
Indicator Gaps and Limitations
Each ROE question focuses on a set of interrelated environ-
mental issues (described in the "Introduction" to the question)
about which there is a good scientific understanding. In gen-
eral, there are ROE indicators that describe status and trends
relating to some but not all of these issues. The "Discussion"
section for each question describes the limitations in the cur-
rent indicators and their underlying data, as well as gaps where
no appropriate indicators are available to answer important
parts of the questions. EPA is working to strategically analyze
gaps and limitations in order to identify priorities for develop-
ing additional indicators and improving existing indicators.
This work will:
• Expand EPA's ability to present indicators and supporting
data at variable geographic scales. This will likely involve
scaling National Indicators in a way that recognizes impor-
tant natural boundaries in air, land, and water, while at the
same time presenting the data in a way that is meaningful
and useful to EPA's Regions and other stakeholders, and
developing a strategy for the incorporation of many more
regional and sub-regional indicators consistent with the
hierarchical frame-work described above in the "Synthesis
and Integration" section.
• Strengthen existing indicators, both by resolving their limi-
tations and by incorporating statistical analysis in order to
quantify the uncertainty in current status and trends.
• Identify what indicators are most needed to answer the
ROE questions, taking into consideration new or emerging
technologies and research needs to support future develop-
ment of these indicators.
• Utilize improved research, science, and technology to
develop new indicators.
• Work with the scientific community to ensure that the
information reported continues to meet EPA's high stan-
dards for science. EPA's Science Advisory Board has recom-
mended that EPA revisit the indicator criteria to achieve a
better balance between inclusiveness and sound science.
Partnerships with federal, state, and non-governmental orga-
nizations to support indicator development and improvement
through coordinated research, monitoring, and data sharing
•will be critical to fulfilling this commitment.
Emerging Issues
In this report, "emerging issues" are issues whose potential to
affect human health and the environment is not well under-
stood. Emerging issues pose different challenges to EPA's ability
to answer the ROE questions than do indicator gaps and limita-
tions. For example, many emerging issues have only recently
been described in the scientific literature and popular press.
Therefore, the current state of scientific understanding makes
it unclear -whether indicators are needed, and if so, how they
should be constructed and tracked. Areas where issues poten-
tially relevant to the ROE questions are emerging include:
• New technologies, contaminants, or environmen-
tal effects potentially related to such contaminants.
Examples include brominated flame retardants;1'2 residues of
Pharmaceuticals and personal care products;3'4'5 air pollutants
1 Rayne, S., M.G. Ikonomou, and B. Antcliffe. 2003. Rapidly increasing poly-
brominated diphenyl ether concentrations in the Columbia River system
from 1992 to 2000. Environ. Sci.Technol. 37(13):2847-2854.
2 Birnbaum, L.S., and D.E Staskal. 2004. Brominated flame retardants: Cause for
concern? Environ. Health Perspect. 112(1):9-17.
3 Daughton, C.G., andT.A.Ternes. 1999. Pharmaceuticals and personal care
products in the environment: Agents of subtle change? Environ. Health
Perspect. 107(Suppl 6):907-944.
Koplin, D.W., E.T. Furlong, M.T. Meyer, E.M.Thurman, S.D. Zaugg, L.B.
Barber, and H.T. Buxton. 2002. Pharmaceuticals, hormones, and other
organic wastewater contaminants in U.S. streams, 1999-2000: A national
reconnaissance. Environ. Sci.Technol. 36:1202-1211.
Lindsey, M.E., M.T. Meyer, and E.M.Thurman. 2001. Analysis of trace levels of
sulfonamide and tetracycline antimicrobials in groundwater and surface water
using solid-phase extraction and liquid chromatography/mass spectrometry
Anal. Chem. 73(19):4640-4646.
7-2
EPA's 2008 Report on the Environment
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related to the use of alternative fuels (e.g., biodiesel);6 new
chemicals and new uses for existing chemicals;7 wastes that
contain multiple materials that are challenging to separate,
particularly for recycling and reuse;8 the growing field of
nanotechnology and the potential release of engineered
nanomaterials (e.g., nanoparticles) to the environment;9 and
diseases and conditions for which there is emerging evidence
that exposure to environmental contaminants may be a risk
factor (see Section 5.4.3).
Issues for which the inherent complexity of the inter-
actions between pollutants, environmental media,
and ecological systems makes it unclear what should
be measured. Examples include (1) interactions between
changing climate and feedback mechanisms and the effects of
a wide range of pollutants on human health, water resources,
ecosystems, coastal areas, and other valued resources,10'11'12'13
including the distribution and occurrence of harmful algal
blooms or other pathogens;14 and (2) loss of genetic diversity,
•which may result in the loss of an entire species if that species
becomes less able to adapt to changing conditions.15
These examples are neither definitive nor prioritized, but
offered simply to illustrate the types of challenges that lie ahead.
Morris, R.E.,A.K. Pollack, G.E.Mansell, C. Lindhjem.Y.Jia, and G.Wilson.
2003. Impact of biodiesel fuels on air quality and human health. National
Renewable Energy Laboratory. NREL/SR-540-33793.
U.S. Department of Energy. 2000. Energy and environmental profile of the
U.S. chemical industry. Report prepared by Energetics Incorporated. Colum-
bia, MD.
U.S. Environmental Protection Agency. 2001. Electronics:A new opportunity
for waste prevention, reuse, and recycling. EPA/530/F-01/006.
Oberdorster, G., E. Oberdorster, and J. Oberdorster. 2005. Nanotoxicology:
An emerging discipline evolving from studies of ultrafine particles. Environ.
Health. Perspect. 113:823-839.
Foley J. 2005. Atmospheric science:Tipping points in the tundra. Science
310(5,748):627-628.
11 Milkov, A.V 2004. Global estimates of hydrate-bound gas in marine
sediments: How much is really out there? Earth Sci. Rev. 66(3-4): 183-197.
12 Faeth, P., and S. Greenhalgh. 2000. A climate and environmental strategy for
U.S. agriculture.WRI Issue Brief,World Resources Institute,Washington, DC,
November 2000.
13 Harrison,]., and P. Matson. 2003. Patterns and controls of nitrous oxide
emissions from waters draining a subtropical agricultural valley. Global
Biogeochem. Cycles 17(3):1080.
14 Daniels, N.A., and A. Shafaie. 2000.A review of pathogenic Vibrio infections
for clinicians. Infect. Med. 17(10):665-685.
15 Bagley, M.J., S.E. Franson, S.A. Christ, E.R.Waits, and G.RToth. 2003.
Genetic diversity as an indicator of ecosystem condition and sustainability:
Utility for regional assessments of stream condition in the eastern United
States. U.S. Environmental Protection Agency. EPA/600/R-03/056.
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Appendix A:
Acronyms and Glossary
This glossary provides definitions for a limited set of
terms. Most of these terms are included because they
have a particular usage or meaning either within EPA
or in the context of this report. A few others are included to
Acronyms
AAPCC American Association of Poison Control Centers
ADHD attention-deficit/hyperactivity disorder
ANC acid neutralizing capacity
AQI Air Quality Index
AQS Air Quality System
ARMS Agricultural Resources Management Survey
AWQC-AL ambient water-quality criterion for the
protection of aquatic life
BBS Breeding Bird Survey
C-CAP Coastal Change Analysis Program
CDC Centers for Disease Control and Prevention
CERCLIS Comprehensive Environmental Response,
Compensation, and Liability Information System
CFC chlorofluorocarbon
CH4 methane
CO carbon monoxide
CO2 carbon dioxide
CWS community water system
DDE dichlorodiphenyldichloroethane
DDT dichlorodiphenyltrichloroethane
DO dissolved oxygen
ECI Ecological Connectivity Indicator
EEC1 effective equivalent troposphere chlorine
EESC effective equivalent stratospheric chlorine
EMAP Environmental Monitoring and Assessment
Program
EPA Environmental Protection Agency
ERS Economic Research Service
ETS environmental tobacco smoke
FIA Forest Inventory and Analysis
FY fiscal year
GHG greenhouse gas
GI gastrointestinal
GIS geographic information system
GOME Global Ozone Monitoring Experiment
GWP global warming potential
ensure understanding of intended meaning because they are
key terms within this report. This glossary does not include
other scientific terms for which standard definitions are
readily available.
HAP
HCB
HCFC
HFC
HUG
IBI
ICD
IMPROVE
K
LEW
LOD
LTM
LUMCON
MCL
hazardous air pollutant
hexachlorob enzene
halogenated fluorocarbon
hydrofluorocarbon
hydrologic unit code
Index of Biological Integrity
International Classification of Diseases
Interagency Monitoring of Protected Visual
Environments
potassium
low birthweight
level of detection
Long-Term Monitoring
Louisiana Universities Marine Consortium
Maximum Contaminant Level
kilometer
microequivalents per liter
micrograms per deciliter
micrograms per liter
micrograms per cubic meter
micron
millimeters per year
million tons
metric tons of carbon per year
nanograms per gram
nanograms per milliliter
picograms per gram
parts per billion
parts per million
parts per trillion
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•1
•
^^1
^
X
LU
Q_
Q_
MDL
MMT
MRLC
MSA
N
N2O
NAAQS
NASA
NASS
NATA
NAWQA
NCA
NCDC
NCHS
NCI
NEDS
NEI
NHANES
NHIS
NIS
NIWA
NLCD
NNDSS
NOAA
NO
NO2
NO
x
NPL
NRG
NRCS
NRI
NVSS
°3
ODS
O/E
OMB
OP
OSWER
P
method detection limit
methylcyclopentadienyl manganese tricarbonyl
Multi-Resolution Land Characteristics
metropolitan statistical area
nitrogen
nitrous oxide
National Ambient Air Quality Standards
National Air and Space Administration
National Agricultural Statistics Service
National-Scale Air Toxics Assessment
National Water-Quality Assessment
National Coastal Assessment
National Climatic Data Center
National Center for Health Statistics
National Cancer Institute
National Emissions Data System
National Emissions Inventory
National Health and Nutrition Examination
Survey
National Health Interview Survey
non-indigenous species
National Institute of Water and Atmospheric
Research
National Land Cover Database or National Land
Cover Dataset
National Notifiable Diseases Surveillance System
National Oceanic and Atmospheric
Administration
nitric oxide
nitrogen dioxide
nitrogen oxides
National Priorities List
National Research Council
Natural Resources Conservation Service
National Resources Inventory
National Vital Statistics System
ozone
ozone-depleting substance
observed/expected
Office of Management and Budget
organophosphate
Office of Solid Waste and Emergency Response
phosphorus
PAH polycyclic aromatic hydrocarbon
PAN peroxyacetyl nitrate
PBDE polybrominated diphenyl ether
PBT persistent, bioaccumulative, and toxic
PCB polychlorinated biphenyl
PCC Poison Control Center
PDP Pesticide Data Program
PFC perfluorinated carbon
PM particulate matter
PM2 5 particles with aerodynamic diameters less than or
equal to 2.5 microns
PMJO particles with aerodynamic diameters less than or
equal to 10 microns
RBS Relative Bed Stability
RCRA Resource Conservation and Recovery Act
RfC reference concentration
ROE Report on the Environment
SAB Science Advisory Board
SAV submerged aquatic vegetation
SBUV Solar Backscatter Ultraviolet
SEER Surveillance, Epidemiology, and End Results
SEF Southeastern Ecological Frame-work
SF, sulfur hexafluoride
6
SO2 sulfur dioxide
SST sea surface temperature
TCDD 2,3,7,8-tetrachlorodibenzo-p-dioxin
TEQ toxic equivalency quotient
TESS Toxic Exposure Surveillance System
TIME Temporally Integrated Monitoring of Ecosystems
TOMS Total Ozone Mapping Spectrometer
TRI Toxics Release Inventory
TSDF treatment, storage, and disposal facility
TSP total suspended particulates
TT Treatment Technique
USDA United States Department of Agriculture
USGS United States Geological Survey
UV ultraviolet
VOC volatile organic compound
WBDO waterborne disease outbreak
WISCARS Web-Based Injury Statistics Query and
Reporting System
WSA Wadeable Streams Assessment
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YPLL
years of potential life lost
Glossary
advisory: A nonregulatory document that communicates
risk information to those who may have to make risk
management decisions. For example, a fish consumption
advisory may recommend that people limit or avoid eating
certain species offish caught from certain lakes, rivers,
or coastal waters. In some cases, advisories may include
recommendations for specific groups (such as infants,
children, the elderly, or women who are pregnant or may
become pregnant).
agricultural and animal waste: Waste generated by the
production and harvest of crops or trees or the rearing of
animals. Animal waste is a subset of agricultural waste and
includes waste (e.g., feed waste, bedding and litter, and feedlot
and paddock runoff) from livestock, dairy, and other animal-
related agricultural and farming practices.
air pollutant: Any substance in air that could, in high enough
concentration, harm humans, animals, vegetation, or material.
Air pollutants can include almost any natural or artificial
composition of matter capable of being airborne—solid
particles, liquid droplets, gases, or a combination thereof.
Air pollutants are often grouped in categories for ease in
classification; some of the categories are sulfur compounds,
volatile organic compounds, particulate matter, nitrogen
compounds, and radioactive compounds.
Air Quality Index (AQI): An index for reporting daily air
quality that characterizes air pollution levels and associated
health effects that might be of concern. EPA calculates the
AQI for five criteria pollutants. AQI values range from 0 to
500; the higher the AQI value, the greater the level of air
pollution and the greater the health concern. AQI values
below 100 are generally thought of as satisfactory. When
AQI values are above 100, air quality is considered to be
unhealthy—at first for certain sensitive groups of people,
then for everyone as AQI values get higher. Refer to EPA's
AIRNOW Web site (http://www.epa.gov/airnow) for more
information on the AQI and how it is calculated.
Air Quality System (AQS): EPA's electronic repository of
ambient air monitoring data collected by EPA, state, local,
and tribal air pollution control agencies from thousands of
monitoring stations. The AQS contains monitoring data,
descriptive information about monitoring stations, and data
quality assurance and quality control information.
air toxics: Air pollutants that cause or may cause cancer or
other serious health effects, such as reproductive effects or
birth defects, or adverse environmental and ecological effects.
Examples of toxic air pollutants include benzene (found in
gasoline), perchloroethylene (emitted from some dry cleaning
facilities), and methylene chloride (used as a solvent by a
number of industries). Air toxics are also known as hazardous
air pollutants.
anthropogenic: Originating from humans; not naturally
occurring.
area source: A source of air pollution that is released over an
area that cannot be classified as a point source. Area sources
can include vehicles and other small engines, small businesses
and household activities, or biogenic sources such as a forest
that releases hydrocarbons.
B
baseline: A reference condition against which changes or
trends are judged—usually a set of conditions that exist at a
particular point in time.
benchmark: A concentration or other accepted measure
against which environmental conditions are compared.
bioaccumulative compound: A compound that tends
to accumulate in tissues and build up in food webs. Some
bioaccumulative compounds can potentially have adverse
effects on ecosystems or human health.
biogenic source: An air emissions source created by some
sort of biological activity. Examples include emissions resulting
from microbial activity in soils and emissions from trees and
other vegetation. Emissions from biogenic sources are a subset
of emissions from natural sources (see natural source).
biological balance: The interrelationships among organisms,
including the structure of food webs and the ability of
ecological systems to maintain themselves over time. Balance
is a dynamic characteristic, rather than a fixed state.
biological diversity: The variety and variability among
living organisms and the ecological complexes in which
they occur. Though it most often refers to the numbers of
species, the term can apply to levels of organization ranging
from genes to ecosystems.
biomarker: A molecular or cellular indicator (or "marker")
of an event or condition (exposure, effect, susceptibility) in a
biological system or sample. It is the product of an interaction
between a contaminant and some target molecule or cell.
biomarker of effect: A measure of disease progression,
representing a measurable alteration at the molecular,
cellular, or some other structural level in the body that can
be recognized as a potential or established adverse health
effect. Such a biomarker can indicate a biological response or
health effect related to a chemical or other stressor; however,
it is not always possible to link a biomarker with exposure to
a single substance.
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biomarker of exposure: The level of a contaminant or
its metabolite collected from the body or from substances
produced or excreted within biological systems. In humans,
this measurement can reflect the amount of the contaminant
that is stored in the body, and is sometimes referred to as the
body burden. It indicates the level of exposure.
biomarker of susceptibility: A measurement of individual
factors that can affect response to environmental agents.
Examples include enzymes whose presence or absence may
reflect a particular genetic condition.
biomonitoring: The measurement of human tissues or
excreta from biological systems for direct or indirect evidence
of exposure to chemical, biological, or radiological substances.
biotic environment: The biological component of an
ecosystem, including plants and animals.
cleanup: Action taken to deal with a release (or threat of
release) of a hazardous substance that could affect humans
and/or the environment. This term is sometimes used
interchangeably with the terms "remedial action," "removal
action," "response action," and "corrective action."
climate change: A term sometimes used to refer to all forms
of climatic inconsistency; because the Earth's climate is never
static, the term is more properly used to imply a significant
change from one climatic condition to another. In some cases,
"climate change" has been used synonymously with "global
warming." Scientists, however, tend to use "climate change"
in the wider sense to also include natural changes in climate.
coastal •waters: Waters at the interface between terrestrial
environments and the open ocean. Many unique habitats lie
in coastal waters—for example, estuaries, coastal wetlands,
seagrass meadows, coral reefs, mangrove and kelp forests, and
upwelling areas.
community: In ecology, an assemblage of populations of
different species within a specified location in space and
time. Sometimes, a particular subgrouping may be specified,
such as the fish community in a lake or the soil arthropod
community in a forest.
community •water system: A water system that supplies
drinking water to 25 or more of the same people year-round
in their residences.
condition: The state of a resource, generally reflecting
a combination of physical, chemical, and biological
characteristics such as temperature, water clarity, chemical
composition, or the status of biological communities. ROE
questions address the condition of fresh surface waters, ground
•water, wetlands, coastal waters, recreational waters, and
consumable fish and shellfish. (Also see ecological condition?)
construction and demolition debris: Waste materials
generated during the construction, renovation, and demolition
of buildings, roads, and bridges. Construction and demolition
debris often contains bulky, heavy materials such as concrete,
•wood (from buildings), asphalt (from roads and roofing
shingles), gypsum (from drywall), metals, bricks, glass, plastics,
building components (doors, windows, plumbing fixtures),
and trees, stumps, earth, and rock from clearing sites.
contaminant: Any physical, chemical, biological, or
radiological substance or matter that has an adverse effect on
air, \vater, or soil.
contaminated land: Land that has been polluted with
hazardous materials and requires cleanup or remediation.
Contaminated lands include sites contaminated as a result of
improper handling or disposal of toxic and hazardous wastes,
sites \vhere improper handling or accidents released toxic or
hazardous materials that are not wastes, and sites where toxics
may have been deposited by wind or flooding.
criteria pollutants: A group of six -widespread and common
air pollutants that EPA regulates on the basis of standards
set to protect public health or the environment (see National
Ambient Air Quality Standards). The six criteria pollutants are
carbon monoxide, lead, nitrogen dioxide, ozone, particulate
matter, and sulfur dioxide.
deleted NPL site: A site that has been deleted from the
Superfund National Priorities List because its cleanup goals
have been met and there is no further need for federal action.
(See Superfund and National Priorities List?)
drinking -water quality: Refers to -whether contaminants are
present in -water that people drink—including -water from the
tap, private wells, hauled -water, untreated surface -water sources,
and bottled -water—at levels that could affect human health.
drinking -water standards: Regulations that EPA sets to
control the level of contaminants in the nation's drinking
•water. Enforceable standards include Maximum Contaminant
Levels (MCLs) and Treatment Techniques (TTs) (see separate
entries for each). Drinking -water standards apply to all public
•water systems (see public water system).
ecological condition: A term referring to the state of
the physical, chemical, and biological characteristics of
the environment, and the processes and interactions that
connect them.
ecological connectivity: A term referring to the connected
system of open space throughout an ecosystem and adjacent
ecosystems. Includes the presence of ecotones, the transitional
regions between ecosystems.
ecological processes: The metabolic functions of
ecosystems—energy flow, elemental cycling, and the
production, consumption, and decomposition of organic matter.
ecological system: A hierarchically nested area that
includes all living organisms (people, plants, animals, and
microorganisms), their physical surroundings (such as soil,
•water, and air), and the natural cycles that sustain them.
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ecoregion: An area within which the ecosystems—and the
type, quality, and quantity of environmental resources—
are generally similar. An ecoregion can serve as a spatial
frame-work for the research, assessment, management, and
monitoring of ecosystems and ecosystem components. Several
different classification schemes have been developed, at various
resolutions. For more information about EPA's ecoregion
designations for North America, visit http://www.epa.gov/
wed/pages/ecoregions/ecoregions.htm.
ecosystem: The interacting system of a particular biological
community and its non-living environmental surroundings, or
a class of such systems (e.g., forests or wetlands).
emission factor: The relationship between the amount of
pollution produced by a particular source and the amount of
raw material processed. For example, an emission factor for
a blast furnace making iron might be pounds of particulates
emitted per ton of raw materials processed.
emission inventory: A listing, by source and pollutant, of
the amount of air pollutants discharged into the atmosphere.
Emission inventories can be based on emissions estimates,
emissions measurements, or both.
endpoint: A biological or ecological characteristic that is the
basis for evaluation or measurement.
end state: Any one of a number of ecosystem characteristics
observed at a point in time. The term is commonly used to
represent the results of ecological processes.
EPA Region: One often EPA geographic divisions, each
responsible for executing the Agency's programs within a
specific group of states and territories. A map of the EPA
Regions is provided in Chapter 1, Exhibit 1-2.
ephemeral -waters: Water bodies (e.g., streams or-wetlands)
that contain -water for brief periods, usually in direct response
to a precipitation event. Ephemeral -waters generally flow for a
shorter time period than intermittent -waters, although in some
cases the terms are used interchangeably (see intermittent waters).
exposure: For humans, the amount of a chemical, physical,
or biological contaminant at the outer boundary of the body
available for exchange or intake via inhalation, ingestion, or
skin or eye contact.
extent: The amount and distribution of a resource, -which
may be measured in terms of spatial area, volume, depth, or
flow (e.g., for-water resources). ROE questions address the
extent of fresh surface -waters, ground -water, -wetlands, and
coastal -waters.
extraction and mining -waste: Soil and rock generated
during the process of gaining access to the ore or mineral
body, as -well as -water that infiltrates the mine during the
extraction process. This category also includes certain -wastes
associated -with the beneficiation of ores and minerals,
including -wastes from the folio-wing activities: crushing,
grinding, -washing, dissolution, crystallization, filtration,
sorting, sizing, drying, sintering, pelletizing, briquetting,
calcining to remove -water and/or carbon dioxide, roasting in
preparation for leaching (except -where the roasting/leaching
sequence produces a final or intermediate product that does
not undergo further beneficiation or processing), gravity
concentration, magnetic separation, electrostatic separation,
floatation, ion exchange, solvent extraction, electro-winning,
precipitation, amalgamation, and heap, dump, vat, tank, and
in situ leaching.
final NPL site: A site that has been formally added to the
Superfund National Priorities List. (See Superfund and National
Priorities List.)
finished -water: Water that has been treated and is ready to be
delivered to customers.
fossil fuel combustion -waste: Waste from the combustion
of oil, natural gas, or petroleum coke; the combustion of coal
at electric utilities and independent power-producing facilities,
non-utilities, and facilities -with fluidized bed combustion
technology; or the combustion of mixtures of coal and other
fuels (i.e., coburning of coal -with other fuels) -where coal is at
least 50 percent of the total fuel.
global climate change: See climate change.
greenhouse gas: Any gas that absorbs infrared radiation
in the atmosphere. Greenhouse gases include -water vapor,
carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O),
halogenated fluorocarbons (HCFCs), ozone (O3), perfluorinated
carbons (PFCs), and hydrofluorocarbons (HFCs).
H
hazardous air pollutants: See air toxics.
hazardous -waste: Waste -with properties that make it
dangerous or potentially harmful to human health or
the environment. The universe of hazardous -wastes is
large and diverse. Hazardous -wastes can be liquids, solids,
contained gases, or sludges. They can be the byproducts of
manufacturing processes or simply discarded commercial
products, like cleaning fluids or pesticides. Hazardous -waste
is regulated under the Resource Conservation and Recovery
Act (RCRA) Subtitle C (see RCRA hazardous waste for the
regulatory definition). States can identify additional -wastes as
hazardous beyond those identified by EPA.
health-based standards: Standards based on contaminant
concentrations in environmental media or exposure doses that
are likely to be -without an appreciable risk of adverse health
effects in humans. (Some health-based standards allow for
consideration of technological and cost limitations.)
hypoxia: The occurrence of low dissolved oxygen
concentrations in -water. Hypoxia is generally defined -with
respect to saturation; because saturation levels vary -with
temperature and salinity, the concentration that defines
hypoxia may vary seasonally and geographically. In practice,
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Q_
Q_
scientists often use a threshold of 2 parts per million, the
generally accepted minimum required for most marine life to
survive and reproduce.
I
impervious surface: A hard surface area that either prevents
or retards the entry of water into the soil mantle or causes
•water to run off the surface in greater quantities or at an
increased rate of flow. Common impervious surfaces include
rooftops, walkways, patios, drive-ways, parking lots, storage
areas, concrete or asphalt paving, and gravel roads.
index: A single number, derived from two or more
environmental variables, that is intended to simplify complex
information. For example, the Index of Biological Integrity
combines several metrics of benthic community condition
into a single index score.
index period: In EPA's aquatic resource monitoring, a
term used to describe the portion of the year when data
are collected. The index period is often selected based on
ecological considerations.
indicator: A numerical value derived from actual
measurements of a stressor, state or ambient condition,
exposure, or human health or ecological condition over
a specified geographic domain, whose trends over time
represent or draw attention to underlying trends in the
condition of the environment.
industrial non-hazardous waste: Waste generated from
processes associated with the production of goods and
products, such as electric power generation and manufacturing
of materials such as pulp and paper, iron and steel, glass, and
concrete. This waste usually is not classified as municipal solid
•waste by the federal government, but some states may classify
it as such if it enters the municipal solid waste stream.
industrial source: A term used in this report to describe
air emissions sources of industrial origin. The report breaks
industrial sources down into contributions from selected
industries, as appropriate.
intermittent •waters: Water bodies (e.g., streams or wetlands)
that contain water for part of each year, due to precipitation
events and some ground water contributions. Intermittent
streams and wetlands typically contain water for weeks or
months, while "ephemeral" streams and wetlands contain
water for briefer periods—but in some cases these terms are
used interchangeably (see ephemeral waters).
invasive species: A non-indigenous plant or animal species
that can harm the environment, human health, or the economy.
land treatment unit: A site where physical, chemical,
and biological processes occurring in the topsoil layers (e.g.,
naturally occurring soil microbes and sunlight) are used to
treat and contain waste. Hazardous waste is applied directly
to the soil surface or incorporated into the upper layers of
the soil, \vhere its constituents are degraded, transformed,
or immobilized. Liner systems or leachate collection and
removal systems are not required for land treatment units.
Closure consists primarily of placing a vegetative cover over
the unit and certifying that hazardous constituent levels in the
treatment zone do not exceed background levels.
landfill: A disposal site for solid -wastes spread in layers,
compacted to the smallest practical volume, and covered by
material (e.g., soil). Landfills are designed to isolate -waste
from the surrounding environment (e.g., ground -water,
rain, air). Landfills are subject to requirements that include
installing and maintaining a final cover, operating leachate
collection and removal systems, maintaining and monitoring
the leak detection system, ground -water monitoring,
preventing storm -water run-on and -off, and installing and
protecting surveyed benchmarks.
M
Maximum Contaminant Level (MCL): The highest level
of a contaminant that EPA allows in drinking -water. MCLs
are enforceable standards that ensure that drinking -water does
not pose either a short-term or long-term health risk. EPA
sets MCLs at levels that are economically and technologically
feasible. Some states set MCLs that are more strict than EPA's.
medical -waste: Any solid -waste generated in the diagnosis,
treatment, or immunization of human beings or animals, in
research pertaining thereto, or in the production or testing
of biologicals, excluding hazardous -waste identified or listed
under 40 CFR Part 261 or any household -waste as defined in
40 CFR Sub-Section 261.4(b)(l).
metal mining sector: Metal mining facilities that fall
•within Standard Industrial Classification Code 10 and must
report to the Toxics Release Inventory in accordance -with
Section 313 of the Emergency Planning and Community
Right to Know Act.
mobile source: A term used to describe a -wide variety of
vehicles, engines, and equipment that generate air pollution
and that move, or can be moved, from place to place.
"On-road" sources are vehicles used on roads to transport
passengers or freight. "Nonroad" sources include vehicles,
engines, and equipment used for construction, agriculture,
transportation, recreation, and many other purposes.
municipal solid -waste: Waste from homes, institutions,
and commercial sources consisting of everyday items such as
product packaging, grass clippings, furniture, clothing, bottles
and cans, food scraps, newspapers, appliances, consumer
electronics, and batteries. (Excluded from this category are
municipal -waste-water treatment sludges, industrial process
•wastes, automobile bodies, combustion ash, and construction
and demolition debris.)
N
National Ambient Air Quality Standards (NAAQS):
Standards established by EPA that apply to outdoor air
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throughout the country. The Clean Air Act established two
types of national air quality standards. Primary standards
set limits to protect public health, including the health of
"sensitive" populations such as asthmatics, children, and
the elderly. Secondary standards set limits to protect public
•welfare, including protection against decreased visibility and
damage to animals, crops, vegetation, and buildings. EPA has
set NAAQS for the six criteria pollutants.
National Indicator: An ROE indicator for which nationally
consistent data are available, and which helps to answer an
ROE question at a national scale. Some National Indicators also
present data broken down by EPA Region. (See ROE indicator.)
National Priorities List (NPL): EPA's list of the most
serious uncontrolled or abandoned hazardous waste sites
identified for possible long-term remedial action under
Superfund. (See Superfund.)
natural source: A term used in this report to describe any
air emissions source of natural origin. Examples include
volcanoes, wild fires, wind-blown dust, and releases due to
biological processes (see biogenic source).
non-indigenous species: A species that has been
introduced by human action, either intentionally or by
accident, into an area outside its natural geographical range;
also called an alien, exotic, introduced, or non-native species.
Certain non-indigenous species are considered "invasive."
(See invasive species?)
non-production-related waste: Waste that is not
production-related; for example, waste associated with
catastrophic events and cleanup actions. Toxic chemicals in
non-production-related waste must be reported to the Toxics
Release Inventory (see Toxics Release Inventory).
non-transient non-community water system: A type of
public water system that supplies water to 25 or more of the
same people at least 6 months per year in places other than
their residences. Some examples are schools, factories, office
buildings, and hospitals that have their own water systems.
(See public water system?)
nonpoint source: A diffuse source of pollution, having no
single point of origin. This term is commonly used to describe
\vater pollution caused by rainfall or snowmelt moving over
and through the ground and carrying natural and human-
made contaminants into lakes, rivers, streams, wetlands,
estuaries, other coastal waters, and ground water. Atmospheric
deposition and hydrologic modification are also sources of
nonpoint water pollution.
non-public •water system: A water system that does not
provide water for human consumption through at least 15
service connections, or regularly serve at least 25 individuals,
for at least 60 days per year.
nutrient: Any substance assimilated by living things that
promotes growth. The term is generally applied to nitrogen
and phosphorus but is also applied to other essential and trace
elements.
oil and gas production •waste: Gas and oil drilling muds,
oil production brines, and other waste associated with
exploration for, or development and production of, crude oil
or natural gas.
onsite treatment: See treatment.
ozone-depleting substance: Any compound that
contributes to stratospheric ozone depletion (see ozone
depletion).
ozone depletion: Destruction of the stratospheric ozone
layer, which shields the Earth from ultraviolet radiation
harmful to life. This destruction of ozone is caused by the
breakdown of certain chlorine- and/or bromine-containing
compounds (chlorofluorocarbons or halons). These
compounds break down when they reach the stratosphere and
then catalytically destroy ozone molecules.
point source: A fixed location or facility that discharges
pollution—for example, a factory smokestack, a ship, an ore
pit, a ditch, or a pipe discharging treated industrial -waste-water
or treated sewage into a -water-way.
pollutant: Any substance introduced into the environment
that may adversely affect the usefulness of a resource or
the health of humans, animals, or ecosystems. For most
environmental media, this term is commonly understood to
refer to substances introduced by human activities. In the case
of air, the convention is to include substances emitted from
natural sources as -well (see air pollutant).
population: In ecology, a group of interbreeding organisms
occupying a particular space. In other contexts, including
human health, this term generally refers to the number of
humans living in a designated area.
precursor: In photochemistry, any compound antecedent
to a pollutant. For example, volatile organic compounds
(VOCs) and nitrogen oxides react in sunlight to form
ozone or other photochemical oxidants. As such, VOCs and
nitrogen oxides are precursors.
primary pollutant: Any pollutant that is emitted into the
atmosphere directly from its source and that retains the same
chemical form. An example of a primary pollutant is dust that
blows into the air from a landfill.
Priority Chemicals: A set of chemicals, found in the nation's
products and -wastes, that EPA targets for voluntary reduction
(or recovery and recycling if they cannot be eliminated
or reduced at the source). The list of Priority Chemicals
is available at http://www.epa.gov/epaoswer/hazwaste/
minimize/chemlist.htm.
production-related -waste: The sum of a facility's
production-related onsite -waste releases, onsite -waste
management (recycling, treatment, and combustion for
energy recovery), and offsite transfers for disposal, treatment,
EPA's 2008 Report on the Environment
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recycling, or energy recovery. Toxic chemicals in production-
related waste must be reported to the Toxics Release Inventory
(see Toxics Release Inventory).
public •water system: A system that provides water for
human consumption through at least 15 service connections,
or regularly serves at least 25 individuals, for at least 60 days
per year. Public water systems are divided into three categories
(see community water system, non-transient non-community water
system, and transient non-community water system). Examples
of public water systems include municipal water companies,
homeowner associations, schools, businesses, campgrounds,
and shopping malls.
radioactive •waste: Waste containing substances that
emit ionizing radiation. Radioactive waste is classified by
regulation according to its source and/or content. The types
of waste that are typically considered "radioactive waste"
include high-level waste, low-level waste, mixed low-level
•waste, transuranic waste (i.e., elements heavier than uranium),
and certain wastes from the extraction and processing
of uranium or thorium ore. Spent nuclear fuel, which is
produced as a result of the controlled nuclear fission process in
nuclear reactors, is considered a nuclear material rather than
radioactive waste.
RCRA Cleanup Baseline: A priority subset of the universe
of facilities that are subject to cleanup under the Resource
Conservation and Recovery Act (RCRA) due to past or
current treatment, storage, or disposal of hazardous wastes,
and that have historical releases of contamination.
RCRA hazardous •waste: A national regulatory designation
for certain wastes under the Resource Conservation
and Recovery Act (RCRA). Some wastes are given this
designation because they are specifically listed on one of
four RCRA hazardous waste lists (see http://www.epa.
gov/epaoswer/osw/hazwaste.htm). Other wastes receive
this designation because they exhibit at least one of four
characteristics—ignitability, corrosivity, reactivity, or toxicity.
Regional Indicator: An ROE indicator that helps to answer
an ROE question on a smaller-than-national geographic scale.
A Regional Indicator may cover a topic for which nationally
consistent data are unavailable, or it may present an issue that
is of particular concern within a certain geographic area. (See
ROE indicator.)
risk factor: A characteristic (e.g., race, sex, age, obesity) or
variable (e.g., smoking, occupational exposure level) associated
•with increased probability of an adverse effect.
ROE indicator: An indicator that meets the ROE criteria (see
Box 1-1, p. 1-8) and has been peer-reviewed. (See indicator.)
secondary pollutant: Any pollutant that is formed by
atmospheric reactions of precursor or primary emissions. An
example of a secondary pollutant is ground-level ozone, which
forms from chemical reactions involving airborne nitrogen
oxides, airborne volatile organic compounds, and sunlight.
sewage sludge: A semi-solid residue from any of a number of
air or water treatment processes. When treated and processed,
sewage sludge becomes a nutrient-rich organic material called
biosolids.
stratosphere: The layer of the atmosphere that starts about 6
to 9 miles above the Earth's surface at mid-latitudes and lies
atop the troposphere. The stratosphere contains small amounts
of gaseous ozone, which filters out about 99 percent of the
incoming ultraviolet radiation.
stressor: A physical, chemical, or biological entity that can
induce adverse effects on ecosystems or human health.
Superfund: A program, operated under the legislative
authority of the Comprehensive Environmental Response,
Compensation, and Liability Act and the Superfund
Amendments and Reauthorization Act, that funds and carries
out EPA solid \vaste emergency and long-term removal and
remedial activities. These activities include establishing the
National Priorities List, investigating sites for inclusion on
the list, determining their priority, and conducting and/or
supervising cleanup and other remedial actions. (See National
Priorities List.)
toxic chemical: A chemical that can produce injury if
inhaled, swallowed, or absorbed through the skin.
Toxics Release Inventory (TRI): A database containing
detailed information on nearly 650 chemicals and chemical
categories that over 23,000 industrial and other facilities
manage through disposal or other releases, recycling,
combustion for energy recovery, or treatment.
Toxics Release Inventory (TRI) chemicals: The
chemicals and chemical categories that appear on the current
TRI toxic chemical list. As of December 2007, the TRI toxic
chemical list contains 581 individually listed chemicals and
30 chemical categories (including three delimited categories
containing 58 chemicals). The list of TRI chemicals is
available at http://www.epa.gov/tri/chemical/index.htm.
Toxics Release Inventory (TRI) facilities: The facilities
that are required by Section 313 of the Emergency Planning
and Community Right to Know Act to report to the TRI.
In the 2005 reporting year, approximately 23,500 facilities
reported to the TRI.
transient non-community water system: A type of
public \vater system that provides water in a place—such as
a gas station or campground—where people do not remain
for long periods of time. These systems do not have to test or
treat their water for contaminants that pose long-term health
risks, because fewer than 25 people drink the water over a
long period. They still must test their water for microbes and
several chemicals. (See public water system.)
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treatment: Any process that changes the physical, chemical,
or biological character of a waste to make it less of an
environmental threat. Treatment can neutralize the waste,
recover energy or material resources from it, render it less
hazardous, or make it safer to transport, store, or dispose of.
Treatment Technique (TT): A required process intended
to reduce the level of a contaminant in drinking water.
troposphere: The layer of the atmosphere closest to the
Earth's surface. The troposphere extends from the surface up
to about 6 to 9 miles.
u
underground injection: The technology of placing fluids
underground in porous formations of rocks, through wells or
other conveyance systems. The fluids may be water, wastewater,
or water mixed with chemicals. Regulations for disposing
of waste this way vary depending on type of waste. RCRA
hazardous waste is placed in highly regulated (Class 1) wells.
urbanization: The concentration of development in
relatively small areas (cities and suburbs). The U.S. Census
Bureau defines "urban" as referring to areas with more than
1.5 people per acre.
w
wadeable stream: A stream, creek, or small river that is
shallow enough to be sampled using methods that involve
\vading into the water. Wadeable streams typically include
•waters classified as first through fourth order in the Strahler
Stream Order classification system.
•wetland: An area that is inundated or saturated by surface
or ground water at a frequency and duration sufficient to
support, and that under normal circumstances does support, a
prevalence of vegetation typically adapted for life in saturated
soil conditions. Wetlands generally include swamps, marshes,
bogs, and similar areas.
EPA's 2008 Report on the Environment
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Appendix B:
Development of EPA's 2008 ROE
The 2008 ROE was developed by EPA's Office of
Research and Development, working in collaboration
•with EPA's program and Regional offices as well as exter-
nal partners. This appendix describes the key elements of the
2008 ROE development process.
Laying the Foundation
EPA published its Draft Report on the Environment in June
2003 and invited feedback. The Agency received comments
from several sources:
• The Science Advisory Board (SAB) reviewed the 2003 Draft
ROE Technical Document in March 2004, issuing draft
comments shortly after-wards and publishing final comments
in December 2004.1
• Through February 2004, the public provided comments on
the 2003 Draft ROE Technical Document via EPA's online
public comment system.2
• Stakeholders commented on the 2003 Draft ROE Public
Report during six dialogue sessions across the nation in
2003 and early 2004.3
In January 2004, the EPA Administrator requested that work
begin to develop the next version of the ROE. Exhibit B-l
shows the organizational structure for development of EPA's
2008 ROE.4 A standing ROE Work Group took the lead in
all phases of development. The group included five theme
leads, each responsible for development of a particular chapter
of the 2008 ROE, plus representatives of EPA Regions and
other relevant EPA offices. During the development process,
the theme leads coordinated with other federal agencies and
organizations involved in indicator development or data col-
lection. An Environmental Indicators Steering Committee,
composed of senior managers from across the Agency, oversaw
development of the ROE. The Steering Committee reviewed
Work Group activities and draft products.
X
CD
Exhibit B-1. Organizational structure for development of EPA's 2008 ROE
Environmental Indicators
Steering Committee
ROE Work Group
Chapter Leads
Other federal agencies
and organizations
involved in indicator or
data development
• Office of Research and
Development
• Office of Air and Radiation
• Office of Water
• Office of Solid Waste and
Emergency Response
Other Participants
• Office of Prevention, Pesticides
and Toxic Substances
• EPA Regions
• Office of Policy, Economics
and Innovation
• Office of the Chief Financial
Officer
• Office of Environmental
Information
1 U.S. Environmental Protection Agency. 2004. EPA's Draft Report on the
Environment (ROE) 2003: An advisory by the ROE Advisory Panel of the
EPA Science Advisory Board. Science Advisory Board. EPA/SAB/05/004.
2 U.S. Environmental Protection Agency. 2004. E-docket for Draft
Report on the Environmental Technical Document. Docket Number:
OEI-2003-0030.
3 U.S. Environmental Protection Agency. 2004. Summary report of the
National Dialogue on the EPA Draft Report on the Environment 2003.
Office of Environmental Information.
4 An additional organizational element, the Indicators Work Group, was
added to the process as the indicators were being finalized for the July
2005 peer review. The Indicators Work Group provided coordination
between the ROE Work Group and the Environmental Indicators Steering
Committee.
EPA's 2008 Report on the Environment
B-1
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The ROE is based on three components:
• A series of fundamental questions about the condition of
the nation's air, -water, and land; about human exposure and
health; and about the condition of ecological systems. These
are questions that the Agency considers to be of critical
importance to its mission.
• An indicator definition.
• Criteria against -which indicators are evaluated to ensure
that they are useful, objective, transparent, and scientifi-
cally reliable.
The first step in developing the 2008 ROE -was to review and
refine the 2003 Draft ROE version of these components:
• Questions. Over 100 EPA specialists from across the
Agency -were convened in the five ROE theme areas: air,
•water, land, human exposure and health, and ecological
condition. Each theme team was charged with considering
feedback and refining the ROE questions. The questions
•were finalized after review by the Environmental Indicators
Steering Committee in 2004.
• Indicator definition and criteria. The 2003 Draft ROE
indicator definition and criteria were refined for the 2008
ROE using an iterative process that included input from
EPA specialists and review by the Environmental Indica-
tors Steering Committee. Care was taken to ensure that
the criteria were consistent with requirements of EPA's
Information Quality Guidelines.
Indicator Development
Once the questions, definition, and criteria were refined, the
next step was to identify and develop indicators to answer
the questions.
• 2003 Draft ROE indicators were screened against the 2008
ROE indicator definition and criteria. Many 2003 Draft
ROE indicators were proposed for the 2008 ROE; some
•were withdrawn; and some were combined into other indi-
cators (see Appendix C for details).
• Ideas for new indicators were solicited from across EPA,
other federal agencies, and organizations. Newly proposed
indicators were screened for their ability to meet the indica-
tor definition and criteria and for their value in answering
the ROE questions.
For each indicator that passed screening, three components
•were developed: text describing the indicator, a graphic or
table displaying the indicator data, and a metadata form that
documents the data source and quality (see Box B-l).
The 2008 ROE development team worked with staff at other
departments, agencies, and private organizations that originally
developed indicators or provided indicator data to ensure that
indicator graphics, data, and quality assurance information were
up to date and accurate. Indicators were reviewed by the Envi-
ronmental Indicators Steering Committee.
• Describe the physical, chemical, or biological measure-
ments upon \vhich this indicator is based. Are these mea-
surements -widely accepted as scientifically and technically
valid? Explain.
• Describe the sampling design and/or monitoring plan
used to collect the data over time and space. Is it based on
sound scientific principles? Explain.
• Describe the conceptual model used to transform these
measurements into an indicator. Is this model -widely
accepted as a scientifically sound representation of the
phenomenon it indicates? Explain.
• For -which ROE question(s) is this indicator used?
To -what extent is the indicator sampling design and
monitoring plan appropriate for answering the relevant
question(s) in the ROE?
• To -what extent does the sampling design represent sensi-
tive populations or ecosystems?
• What, if any, are the established reference points, thresh-
olds, or ranges of values for this indicator that unambigu-
ously reflect the state of the environment?
• What documentation clearly and completely describes the
underlying sampling and analytical procedures used?
To -what extent is the complete data set accessible, includ-
ing metadata, data-dictionaries, and embedded defini-
tions? Are there confidentiality issues that may limit
accessibility to the complete data set?
Are the descriptions of the study or survey design clear,
complete, and sufficient to enable the study or survey to
be reproduced? Explain.
To -what extent are the procedures for quality assur-
ance and quality control of the data documented and
accessible?
What statistical methods, if any, have been used to gener-
alize or portray data beyond the time or spatial locations
•where measurements -were made (e.g., statistical survey
inference, no generalization is possible)? Are these meth-
ods scientifically appropriate?
What uncertainty measurements or estimates are available
for the indicator and/or the underlying data set?
To -what extent do uncertainty and variability impact the
conclusions that can be inferred from the data and the
utility of the indicator?
Describe any limitations, or gaps in the data that may mis-
lead a user about fundamental trends in the indicator over
space or over the time period for -which data are available.
B-2
EPA's 2008 Report on the Environment
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• Indicate the extent to which you think the proposed
indicator is appropriate, adequate, and useful for evaluating
• Indicate the extent to which you think the proposed indi-
cator makes an important contribution to answering the
specific ROE question it is intended to answer.
• To what extent do you think the indicator meets the
indicator definition?
• To what extent do you think the indicator meets each of
the indicator criteria?
• Do you have any suggestions for more effective graphic
presentation of the data? Provide any additional comments,
suggestions, or concerns regarding the indicator that you
have not already noted earlier. In particular, note any limi-
tations to the indicator.
• Select one: Overall, this indicator (1) should be
included in the ROE; (2) should be included in the
ROE with the modifications identified above; or (3)
should not be included in the ROE.
Do any of the proposed indicators clearly seem to be
more appropriate, adequate, or useful for evaluating
a than others? Do any seem to be more important
than the others for answering the question(s) they are
intended to answer?
Are there any additional national-level indicators that
make an important contribution to answering one of
the ROE questions in your topic area, but were not
proposed for the ROE, that you would recommend? As
you consider this question, consider the list of indicators
presented in ROE03 that EPA does not intend to carry
forward to the 2008 ROE, along with EPA's rationale
for withdrawing them. If you disagree with EPA's ratio-
nale and feel any of these indicators should be included
in the ROE, please so indicate in your response to this
question, along with your rationale for why they should
be included.
aThis part of the charge varied according to theme area as follows:
• Air: "our nation's air and therefore useful for contributing to an overall
picture of our nation's air"
• Water: "our nation's waters and for contributing to an overall picture of
our nation's waters"
• Chemicals on land: "trends in chemicals used on land and their effects
on human health and the environment"
• Land wastes: "trends in wastes and their effects on human health and
the environment"
• Human health: "human health and for contributing to an overall pic-
ture of human health"
• Ecological condition: "ecological conditions and therefore useful for
contributing to an overall picture of ecological conditions"
Indicator Peer Review and Public Comment
Once the full suite of proposed indicators was assembled,
all indicators were independently peer-reviewed by nation-
ally recognized experts to ensure that they were scientifically
sound and properly documented, met the indicator definition
and criteria, and were useful for answering the questions posed
in the ROE. Two rounds of review were conducted:
• At a -workshop in July 2005, 21 experts reviewed the initial
set of 88 proposed indicators.
• In November 2005, nine experts reviewed 11 indicators
that \vere new or had been substantially revised since the
July 2005 review.
The peer review, organized by a contractor, was conducted
following the Office of Management and Budget's (OMB's)
specifications for peer review of "Highly Influential Scientific
Assessments" as specified in OMB's "Final Information Quality
Bulletin for Peer Review."5 The reviewer selection criteria, list
of reviewers, charge to reviewers, and reviewer comments can
be found in the peer review summary report.6 EPA announced
the peer reviews in the Federal Register and also posted the
proposed indicators on a Web site for public comment. Key
questions addressed during the review are listed in Box B-2.
After the peer review and public comment period, EPA revised
and finalized the indicators. EPA's responses to reviewer and
public comments are available at EPA's ROE Web site: http://
•www.epa.gov/roe.
ROE Review
Concurrent with indicator development, EPA's ROE team,
•working with specialists across the Agency, developed the
text elements of the 2008 ROE. The final indicators were
incorporated into the text to produce the full 2008 ROE.
This draft document was reviewed internally at EPA, exter-
nally by other federal agencies and OMB, and externally by
SAB (including public comment on the federal docket). EPA
revised the document based on comments and, after the third
review, finalized it for publication.
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5 Office of Management and Budget. 2004. Final information quality bul-
letin for peer review. December 16, 2004.
6 U.S. Environmental Protection Agency. 2006. Report of the peer review
of proposed ROE07 indicators. Office of Research and Development.
EPA's 2008 Report on the Environment
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Appendix C:
Comparison of Indicators Used in
EPA's 2008 ROE and the 2003 Draft ROE
Indicators new to the 2008 report are listed in bold font.
Indicators in the 2003 report but withdrawn in 2008 are
highlighted in gray.
The rationale for withdrawing indicators is explained at the
end of this appendix.
Some indicators are used to answer more than one ROE
question; indicators are listed in the table below only
•where they are first used to answer an ROE question in the
2008 report.
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Air Chapter
Outdoor Air Quality
2008 ROE Indicator Title
Lead Emissions
Ambient Concentrations of Lead
Nitrogen Oxides Emissions
Volatile Organic Compounds Emissions
Ambient Concentrations of Ozone
Ozone Injury to Forest Plants
Particulate Matter Emissions
Ambient Concentrations of Particulate Matter
Regional Haze
Sulfur Dioxide Emissions
Acid Deposition
Corresponding 2003 Draft ROE Indicator Title
Lead Emissions
Ambient Concentrations of Lead
Emissions: Particulate Matter (PM25 and PM10),
Sulfur Dioxide, Nitrogen Oxides, and Volatile Organic
Compounds
Emissions (Utility): Sulfur Dioxide and Nitrogen Oxides
Emissions: Particulate Matter (PM25 and PM10),
Sulfur Dioxide, Nitrogen Oxides, and Volatile Organic
Compounds
Ambient Concentrations of Ozone: 8-hour and 1-hour
Ozone Injury to Trees (from the ecological condition
chapter)
Emissions: Particulate Matter (PM25 and PM10),
Sulfur Dioxide, Nitrogen Oxides, and Volatile Organic
Compounds
Ambient Concentrations of Particulate Matter: PM25
and PM10
Visibility
Emissions: Particulate Matter (PM25 and PM10),
Sulfur Dioxide, Nitrogen Oxides, and Volatile Organic
Compounds
Emissions (Utility): Sulfur Dioxide and Nitrogen Oxides
Deposition: Wet Sulfate and Wet Nitrogen
Atmospheric Deposition of Nitrogen (from the water
chapter)
EPA's 2008 Report on the Environment
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Outdoor Air Quality
2008 ROE Indicator Title
Lake and Stream Acidity
Percent of Days with Air Quality Index Values Greater
Than 100
Air Toxics Emissions
Ambient Concentrations of Benzene
Concentrations of Ozone-Depleting Substances
Ozone Levels over North America
Carbon Monoxide Emissions
Ambient Concentrations of Carbon Monoxide
Ambient Concentrations of Nitrogen Dioxide
Mercury Emissions
Ozone and Particulate Matter Concentrations for U.S.
Counties in the U.S./Mexico Border Region
Ambient Concentrations of Manganese Compounds in EPA
Region 5
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Acid Sensitivity in Lakes and Streams (from the water
chapter)
Number and Percentage of Days That Metropolitan
Statistical Areas (MSAs) Have Air Quality Index (AQI)
Values Greater Than 100
Air Toxics Emissions
Ambient Concentrations of Selected Air Toxics
Concentrations of Ozone-Depleting Substances (Effective
Equivalent Chlorine)
Ozone Levels over North America
Worldwide and U.S. Production of Ozone-Depleting
Substances (ODSs)
Withdrawn
Number of People Living in Areas with Air Quality Levels
Above the NAAQS for Particulate Matter (PM) and Ozone
Greenhouse Gases
2008 ROE Indicator Title
Corresponding 2003 Draft ROE Indicator Title
U.S. Greenhouse Gas Emissions
Atmospheric Concentrations of Greenhouse Gases
Indoor Air Quality
2008 ROE Indicator Title
U.S. Homes Above EPA's Radon Action Level
Blood Cotinine Level
^^^^^^^^^^^^^^H
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
U.S. Homes Above EPA's Radon Action Levels
Blood Cotinine Level; Blood Cotinine Level in Children
(from the human health chapter)
Percentage of Homes Where Young Children Are Exposed
to Environmental Tobacco Smoke
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Water Chapter
Fresh Surface Waters
2008 ROE Indicator Title
High and Low Stream Flows
Nitrogen and Phosphorus in Streams in Agricultural
Watersheds
Nitrogen and Phosphorus Loads in Large Rivers
Pesticides in Streams in Agricultural Watersheds
Benthic Macroinvertebrates in Wadeable Streams
Streambed Stability in Wadeable Streams
Nitrogen and Phosphorus in Wadeable Streams
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Changing Stream Flows
Number/Duration of Dry Stream Flow Periods in
Grassland/Shrublands
Nitrate in Farmland, Forested, and Urban Streams and
Ground Water (partially replaced, partially withdrawn)
Phosphorus in Farmland, Forested, and Urban Streams
(partially replaced, partially withdrawn)
Partly new information and partly from indicator: Movement
of Nitrogen (from the ecological condition chapter)
Pesticides in Farmland Streams and Ground Water
Macroinvertebrate Biotic Integrity Index for Streams
Altered Fresh Water Ecosystems
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Withdrawn
Lake Trophic State Index
Withdrawn
Percent Urban Land Cover in Riparian Areas
Withdrawn
Agricultural Lands in Riparian Areas
Withdrawn
Sedimentation Index
Withdrawn
Nitrate in Farmland, Forested, and Urban Streams and
Ground Water (partially withdrawn)
Withdrawn
Phosphorus in Farmland, Forested, and Urban Streams
(partially withdrawn)
Withdrawn
Phosphorus in Large Rivers
Withdrawn
Atmospheric Deposition of Mercury
Withdrawn
Chemical Contamination in Streams and Ground Water
Withdrawn
Sediment Contamination of Inland Waters
Withdrawn
Fish Index of Biotic Integrity in Streams
Ground Water
2008 ROE Indicator Title
Nitrate and Pesticides in Shallow Ground Water in
Agricultural Watersheds
Corresponding 2003 Draft ROE Indicator Title
Pesticides in Farmland Streams and Ground Water
Nitrate in Farmland, Forested, and Urban Streams and
Ground Water (partially replaced, partially withdrawn)
Nitrate in Farmland, Forested, and Urban Streams and
Ground Water (partially withdrawn)
EPA's 2008 Report on the Environment
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Wetlands
2008 ROE Indicator Title
Wetland Extent, Change, and Sources of Change
Corresponding 2003 Draft ROE Indicator Title
Wetland Extent and Change
Sources of Wetland Change/Loss
Coastal Waters
2008 ROE Indicator Title
Trophic State of Coastal Waters
Coastal Sediment Quality
Coastal Benthic Communities
Submerged Aquatic Vegetation in the Chesapeake Bay
Hypoxia in the Gulf of Mexico and Long Island Sound
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Water Clarity in Coastal Waters
Dissolved Oxygen in Coastal Waters
Chlorophyll Concentrations
Total Nitrogen in Coastal Waters
Total Phosphorus in Coastal Waters
Sediment Contamination of Coastal Waters
Sediment Toxicity in Estuaries
Benthic Community Index (for Coastal Waters) (presented
in both the water and ecological condition chapters)
Submerged Aquatic Vegetation (changed to a Regional
Indicator; from the ecological condition chapter)
Total Organic Carbon in Sediments
Withdrawn
Population Density in Coastal Areas
Drinking Water
2008 ROE Indicator Title
Population Served by Community Water Systems with No
Reported Violations of Health-Based Standards
Corresponding 2003 Draft ROE Indicator Title
Population Served by Community Water Systems That
Meet All Health-Based Standards
Recreational Waters
2008 ROE Indicator Title
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Number of Beach Days That Beaches Are Closed or Under
Advisory
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Consumable Fish and Shellfish
2008 ROE Indicator Title
Coastal Fish Tissue Contaminants
Contaminants in Lake Fish Tissue
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Chemical Contamination (from the ecological condition
chapter) (partially withdrawn)
Contaminants in Fresh Water Fish
Percent of River Miles and Lake Acres Under Fish
Consumption Advisories
:
X
o
Withdrawn
Number of Watersheds Exceeding Health-Based National
Water Quality Criteria for Mercury and PCBs in Fish Tissue
Land Chapter
Land Cover
2008 ROE Indicator Title
Land Cover
Land Cover in the Puget Sound/Georgia Basin
Corresponding 2003 Draft ROE Indicator Title
Extent of Grasslands and Shrublands
Extent of Forest Area, Ownership, and Management
Patches of Forest, Grassland, Shrubland, and Wetland
in Urban/Suburban Areas (from the ecological condition
chapter)
Ecosystem Extent (from the ecological condition chapter)
2008 ROE Indicator Title
Land Use
Urbanization and Population Change
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Extent of Urban and Suburban Lands
Extent of Agricultural Land Uses
Extent of Developed Lands (plus land chapter introduction
from 2003 Draft ROE)
The Farmland Landscape
Withdrawn
Sediment Runoff Potential from Croplands and Pasturelands
EPA's 2008 Report on the Environment
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2008 ROE Indicator Title
Quantity of Municipal Solid Waste Generated and Managed
Quantity of RCRA Hazardous Waste Generated and
Managed
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Quantity of Municipal Solid Waste (MSW) Generated and
Managed
Number and Location of Municipal Solid Waste (MSW)
Landfills
Quantity of RCRA Hazardous Waste Generated and
Managed
Number and Location of RCRA Hazardous Waste
Management Facilities (partially replaced, partially
withdrawn)
Quantity of Radioactive Waste Generated and in Inventory
Withdrawn
Number and Location of Municipal Solid Waste (MSW)
Landfills (partially withdrawn)
Withdrawn
Number and Location of RCRA Hazardous Waste
Management Facilities (partially withdrawn)
Withdrawn
Number and Location of Superfund National Priorities List
(NPL) Sites
Withdrawn
Number and Location of RCRA Corrective Action Sites
Chemicals Used on the Land
2008 ROE Indicator Title
Fertilizer Applied for Agricultural Purposes
Toxic Chemicals in Production-Related Wastes Combusted
for Energy Recovery, Released, Treated, or Recycled
Pesticide Residues in Food
Reported Pesticide Incidents
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Fertilizer Use
Quantity and Type of Toxic Chemicals Released and
Managed
Number and Location of RCRA Hazardous Waste
Management Facilities (partially replaced, partially
withdrawn)
Pesticide Residues in Food
Agricultural Pesticide Use
Withdrawn
Potential Pesticide Runoff from Farm Fields
Withdrawn
Risk of Nitrogen Export
Withdrawn
Risk of Phosphorus Export
Withdrawn
Pesticide Leaching Potential (from the ecological condition
chapter)
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Contaminated Land
2008 ROE Indicator Title
Corresponding 2003 Draft ROE Indicator Title
Current Human Exposures Under Control at High-Priority
Cleanup Sites
Migration of Contaminated Ground Water Under Control at
High-Priority Cleanup Sites
Human Exposure and Health Chapter
Exposure to Environmental Contaminants
X
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2008 ROE Indicator Title
Blood Lead Level
Blood Mercury Level
Blood Cadmium Level
Urinary Pesticide Level
Blood Persistent Organic Pollutants Level
Urinary Phthalate Level
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Blood Lead Level
Blood Lead Level in Children
Blood Mercury Level
Blood Mercury Level in Children
Blood Cadmium Level
Urine Organophosphate Levels to Indicate Pesticides
Urine Arsenic Level
Withdrawn
Blood Volatile Organic Compound Levels
Health Status
ROE 2008 Indicator Title
Life Expectancy at Birth
Infant Mortality
General Mortality
Corresponding 2003 Draft ROE Indicator Title
Life Expectancy
Infant Mortality
(partially based on "Leading Causes of Death" in the
contextual information provided in the 2003 Draft ROE
human health chapter)
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Disease and Conditions
ROE 2008 Indicator Title
Cancer Incidence
Childhood Cancer Incidence
Cardiovascular Disease Prevalence and Mortality
Chronic Obstructive Pulmonary Disease Prevalence and
Mortality
Asthma Prevalence
Infectious Diseases Associated with Environmental
Exposures or Conditions
(with the following new additions: Giardiasis, Lyme
Disease, Rocky Mountain Spotted Fever, West Nile Virus,
Legionellosis)
Birth Defects Prevalence and Mortality
Low Birthweight
Preterm Delivery
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Cancer Incidence
Childhood Cancer Incidence
Cardiovascular Disease Mortality
Cardiovascular Disease Prevalence
Chronic Obstructive Pulmonary Disease Mortality
Asthma Prevalence
Childhood Asthma Prevalence
Cholera Prevalence
Cryptosporidiosis Prevalence
E, co//0157:H7 Prevalence
Hepatitis A Prevalence
Salmonellosis Prevalence
Shigellosis Prevalence
Typhoid Fever Prevalence
Deaths Due to Birth Defects
Birth Defect Incidence
Low Birthweight Incidence
Cancer Mortality
Withdrawn
Asthma Mortality
Withdrawn
Childhood Cancer Mortality
Withdrawn
Childhood Asthma Mortality
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Ecological Condition Chapter
Extent and Distributon
ROE 2008 Indicator Title
Forest Extent and Type
Forest Fragmentation
Ecological Connectivity in EPA Region 4
Relative Ecological Condition of Undeveloped Land in EPA
Region 5
Corresponding 2003 Draft ROE Indicator Title
Extent of Area by Forest Type
Forest Pattern and Fragmentation
E
x
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Withdrawn
Forest Age Class
Withdrawn
Extent of Ponds, Lakes, and Reservoirs
Withdrawn
Extent of Estuaries and Coastline
Diversity and Biological Balance
ROE 2008 Indicator Title
Corresponding 2003 Draft ROE Indicator Title
Bird Populations
Fish Fauna! Intactness
Non-Indigenous Benthic Species in the Estuaries of the
Pacific Northwest
Withdrawn
At-Risk Native Forest Species
Withdrawn
Populations of Representative Forest Species
Withdrawn
Tree Condition
Withdrawn
At-Risk Native Grassland and Shrubland Species
Withdrawn
Population Trends of Invasive and Native Non-Invasive
Bird Species
Withdrawn
At-Risk Native Fresh Water Species
Withdrawn
Non-Native Fresh Water Species
Withdrawn
At-Risk Fresh Water Plant Communities
Withdrawn
Coastal Living Habitats
Withdrawn
Shoreline Types
Withdrawn
Fish Diversity
Withdrawn
At-Risk Native Species
Withdrawn
Bird Community Index
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Ecological Processes
ROE 2008 Indicator Title
Carbon Storage in Forests
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Carbon Storage
Forest Disturbance: Fire, Insects, and Disease
Physical and Chemical Attributes
ROE 2008 Indicator Title
U.S. and Global Mean Temperature and Precipitation
Sea Surface Temperature
Sea Level
Withdrawn
Withdrawn
Withdrawn
Withdrawn
Withdrawn
Withdrawn
Corresponding 2003 Draft ROE Indicator Title
Soil Erosion (Forests)
Soil Erosion (Farmland)
Processes Beyond the Range of Historic Variation
Soil Quality Index
Terrestrial Plant Growth Index
Chemical Contamination (partially withdrawn)
Withdrawn
Ecological Exposure to Contaminants
ROE 2008 Indicator Title
Corresponding 2003 Draft ROE Indicator Title
Animal Deaths and Deformities
Withdrawn
Fish Abnormalities
Withdrawn
Unusual Marine Mortalities
Explanation of Indicators Used in the 2003
Draft ROE But Not in the 2008 ROE
A number of indicators were included in EPA's 2003 Draft
ROE that are not included in the 2008 ROE. The general
reasons for these changes are described below, followed by
indicator-specific explanations.
• Members of the independent scientific review panel that
reviewed the draft indicators for the 2008 ROE recom-
mended their withdrawal.
• The EPA Science Advisory Board Committee review of the
2003 Draft ROE recommended EPA develop and utilize
a more precise definition of "indicator" than was used for
2003 Draft ROE.
• EPA developed a set of specific indicator criteria to provide
a more precise conformance to Office of Management and
Budget and EPA Information Quality Guidelines.
• The 2008 ROE introduced a Regional Pilot Project and
developed and implemented a relevant process. Sub-
National or Regional Indicators that were included in the
2003 Draft ROE but did not go through this pilot are not
included in the 2008 ROE.
A small number of the indicators in 2003 Draft ROE did not
conform to one or more of these requirements. Explanations
for not including these indicators were peer-reviewed by an
independent scientific panel along with the indicators in this
report. Broadly speaking, the explanations for withdrawal fall
into five categories, coded as follows:
• (D) Definition. The indicator fails to meet the improved
indicator definition for the 2008 ROE.
• (C) Criteria. The indicator fails to meet one of the six
indicator criteria that were established to conform to EPA
Information Quality Guidelines.
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• (N) New indicator. The indicator is replaced by a "new"
and superior indicator that -was not available for the 2003
Draft ROE.
• (R) Regional. The indicator is not national in scope and is
not part of the 2008 ROE Regional Pilot Project.
• (P) Peer review. The independent peer review panel rec-
ommended withdrawing the indicator from the 2008 ROE.
The folio-wing information briefly explains the rationale for
withdrawing specific indicators from the 2008 ROE. Each
indicator is categorized as D, C, N, R, or P. The indicators are
organized by chapter.
Air Chapter
Worldwide and U.S. Production of
Ozone-Depleting Substances (ODSs)—C
This 2003 Draft ROE indicator presented estimates of the
amount of ODSs produced -world-wide in 1986 and 1999, and
annual U.S. production from 1958 to 1993. This indicator-was
withdrawn because of issues concerning data reliability and
relevance. Global ODC production data are not reliable -with
respect to comparability among reporting countries. The U.S.
estimates are more reliable because of legal reporting require-
ments and the small number of sources. However, the data set
fails to account for imports, and annual production is not a
good surrogate for emissions of ODCs into the environment
because the time between production and eventual entry into
the environment is highly variable among the various products
and recovery systems.
Number of People Living in Areas with Air Quality Levels
Above the NAAQS for Particulate Matter (PM) and Ozone—C
This 2003 Draft ROE indicator conveyed how many people
(based on census data) lived in counties -where air pollutant
levels at times -were above the level of the NAAQS during the
year stated. It -was intended to give the reader some indication
of the number of people potentially exposed to unhealthy air.
Because of changing populations and air quality standards,
however, this indicator masks actual trends in the levels of air
pollutants. It is not a valid exposure indicator for the ROE
because it is not based on measurement of an actual marker of
exposure measured on or in individuals.
Percentage of Homes Where Young Children Are Exposed
to Environmental Tobacco Smoke—D
This 2003 Draft ROE indicator portrayed the percentage of
homes in the U.S. in which young children were exposed
to tobacco smoke in 1998 versus 1957. The survey -was based
on a questionnaire (do children live in the home, and does
someone -who smokes regularly live in the home), rather than
on measurements of the amount of smoke actually present or
the degree to -which children -were exposed to the resulting
smoke. This indicator violates the ROE indicator definition,
•which requires that indicators be based on actual measure-
ments; furthermore, the 2008 ROE's Blood Cotinine indica-
tor better indicates children's exposure to smoke.
Water Chapter
Altered Fresh Water Ecosystems—C
Percent Urban Land Cover in Riparian Areas—C
Agricultural Lands in Riparian Areas—C
These 2003 Draft ROE indicators were based on the percent-
age of land within 30 meters of the edge of a stream or lake
that is classified as urban or agriculture based on 1991 satellite
data (NLCD). Baseline data are incomplete, there are no refer-
ence points for the appropriate percentage of such cover, and it
is not clear that the indicators could be reproduced with newer
satellite data. There are no data for other alterations such as
damming, channelization, etc.
Lake Trophic State Index—R, C
This 2003 Draft ROE indicator was based on phosphorus data
collected in a one-time statistical sample of lakes in the north-
eastern U.S. during 1991-1994. It is not included in the 2008
ROE Regional Pilot Project.
Sedimentation Index—R, C, N
This 2003 Draft ROE indicator was based on data collected
on freshwater streams in the Mid-Atlantic Highlands Region
during a one-time 1993-1994 statistical survey. It is not
included in the 2008 ROE Regional Pilot Project. The 2008
ROE's Streambed Stability in Wadeable Streams indicator
provides a more complete nation-wide picture of sedimentation
in streams.
Nitrate in Farmland, Forested, and Urban Streams and
Ground Water (partially withdrawn)—N
Phosphorus in Farmland, Forested, and Urban Streams
(partially withdrawn)—N
These 2003 Draft ROE indicators were replaced by two new
indicators, "Nitrogen and Phosphorus in Streams in Agri-
cultural Watersheds" and "Nitrate and Pesticides in Shallow
Ground Water in Agricultural Watersheds." The NAWQA
streams in forested and urban -watersheds -were based on a
small sample size, and may not be representative of forested
and urban streams in general.
Phosphorus in Large Rivers—C
The indicator -was based on phosphorus concentrations in large
rivers sampled periodically by the USGS National Stream
Quality Accounting Network (NASQAN). Monitoring at
many of the large river NASQAN sites has been discontinued.
Information on phosphorus loads in four major rivers has been
incorporated into the new 2008 ROE indicator, Nitrogen and
Phosphorus Loads in Large Rivers.
Atmospheric Deposition of Mercury—C
This indicator -was withdrawn folio-wing peer review of the
indicators because trend data could not be analyzed in time to
revise it.
Chemical Contamination in Streams and Ground Water—C
This 2003 Draft ROE indicator -was based on data from a
large number of USGS National Water Quality Assessment
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(NAWQA) -watersheds. The sampling and analytical protocols
(including the analytes measured) are not comparable across all
NAWQA watersheds.
Sediment Contamination of Inland Waters—C
This 2003 Draft ROE indicator was based on reported con-
centrations of sediment contaminants collected by a large
number of organizations focusing particularly on places where
sediment contamination is perceived to be a problem (the
EPA National Sediment Inventory). The database suffers from
a number of limitations: the data are heavily biased toward
sites at which there is a known or suspected toxicity prob-
lem and to particular geographic areas (non-representative of
the nation), the data cover different dates in different loca-
tions (making estimation of trends difficult), and the data and
procedures used to assign sites to a toxicity category are not
uniform from -watershed to -watershed. It is unsuitable for
trend estimation.
Fish Index of Biotic Integrity in Streams—R, C
This 2003 Draft ROE indicator -was based on fish community
data collected on fresh-water fish in the Mid-Atlantic High-
lands Region during a one-time 1993-1996 statistical survey.
Condition cannot be assessed in streams -where no fish -were
caught, because data -were insufficient to indicate -whether the
stream had poor quality or simply no fish. It is not included in
the 2008 ROE Regional Pilot Project.
Total Organic Carbon in Sediments—R
This 2003 Draft ROE indicator -was based on data collected
in a survey of Mid-Atlantic estuaries during a one-time
1997-1998 statistical survey. It is not included in the 2008 ROE
Regional Pilot Project. Also, total organic carbon in sedi-
ments is useful in understanding sediment toxicity, but there
are unlikely to be trends in sediment total organic carbon, and
therefore it -would be of limited value as an ROE indicator.
Population Density in Coastal Areas—D
Discussion of population density in coastal areas -was moved
to the introduction of the -water chapter section responding to
the question, "What are the trends in the extent and condi-
tion of coastal -waters and their effects on human health and
the environment?"
Number of Beach Days That Beaches Are Closed or
Under Advisory—D
Percent of River Miles and Lake Acres Under Fish
Consumption Advisories—D
These 2003 Draft ROE indicators -were based on the fre-
quency of beach closures or fish consumption advisories as
reported to EPA voluntarily by states and local government
organizations. The data are not nationally or temporally
consistent because of different and changing criteria for
closing beaches or issuing fish consumption advisories in the
different states, many of-which do not involve actual -water
quality measurements. They are therefore administrative
indicators (based on administrative action rather than actual
physical measurements) and fail to meet the definition for
ROE indicators.
Number of Watersheds Exceeding Health-Based
National Water Quality Criteria for Mercury and PCBs in
Fish Tissue—C
This 2003 Draft ROE indicator -was based on voluntary
reporting of mercury contamination using data that had not
undergone formal QA/QC review. It is not representative of
the nation, or suitable for trend monitoring.
Land Chapter
The Farmland Landscape—C
This 2003 Draft ROE indicator represented croplands and the
forests, woodlots, -wetlands, grasslands, and shrublands that
surround or are intermingled -with them, and the degree to
•which croplands dominate the landscape. The indicator relied
on data generated using early 1990s satellite data, and it is
unclear -whether the definition of "farmland landscape" is suf-
ficiently precise to be replicated independently, especially -with
respect to any future satellite data availability.
Sediment Runoff Potential from Croplands and
Pasturelands—C
This 2003 Draft ROE indicator represented the estimated
sediment runoff potential for croplands and pasturelands based
on topography; -weather patterns; soil characteristics; land use,
land cover, and cropping patterns; and the Universal Soil Loss
equation. The indicator addressed "potential" and not actual/
current condition, and relied on a model (the Soil and Water
Assessment Tool: http://www.brc.tamus.edu/swat) to predict
ambient characteristics based on pressure/stressor measure-
ments, -which violates a fundamental ROE protocol on the use
of models in indicators. Trends in this indicator-would likely
be associated only -with trends in land cover, cropping prac-
tices, and -weather (topography and soil type are unlikely to
change). No reliable spatial trend data at the appropriate scale
exist for either cropping practices or land cover, and conse-
quently trends in this indicator -would be difficult to calculate.
Agricultural Pesticide Use—C
Agricultural pesticide usage data, measured at the national
aggregate level for all pesticides, are very difficult to inter-
pret. From one time period to another, the mix of pesticides
changes, pest pressures change, agricultural practices change,
agricultural acreage changes, regulatory status of key uses
changes, and many other important variables change. More-
over, the effects of pesticide usage are encountered at three
levels of the product's life cycle: production, usage, and
residues on foods. The geographic distribution of those effects
renders difficult the interpretation of national usage levels for
all pesticides, taken as a group. While it is of course possible to
compare magnitudes of aggregates at different times, the real
significance for the environment is in the differences in the
content and geographic distribution of the aggregates, not in
the magnitude of the aggregate.
Potential Pesticide Runoff from Farm Fields—C
Pesticide Leaching Potential—C
These 2003 Draft ROE indicators represented the potential
movement of agricultural pesticides from the site of application
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to ground and surface waters, based on estimates of pesticide
leaching and runoff losses derived from soil properties, field
characteristics, management practices, pesticide properties,
and climate for 243 pesticides applied to 120 specific soils in
growing 13 major agronomic crops. The indicators address
"potential" and not actual/current condition, and rely on
models to predict ambient characteristics based on measure-
ments of pressures/stressors. This violates a fundamental ROE
protocol on the use of models in indicators.
Risk of Nitrogen Export—C
Risk of Phosphorus Export—C
These 2003 Draft ROE indicators represented the potential
movement of nitrogen and phosphorus from the site of appli-
cation to surface waters, based on a large empirical dataset
relating land use to nitrogen and phosphorus observed in
receiving streams over several decades at a variety of locations.
The indicators address "potential" and not actual/current
conditions, and rely on statistical models to predict ambient
characteristics based on measurements of pressures/stressors.
This violates a fundamental ROE protocol on the use of mod-
els in indicators.
Quantity of Radioactive Waste Generated and
in Inventory—C
This 2003 Draft ROE indicator was based on production
and inventory data collected by the Department of Energy.
Although the data continue to be collected, they are no longer
publicly available post-September 11, 2001; therefore, ongoing
data trends are not and will not be available for this indicator
in the future. Moreover, the earlier data reflected two distinct
periods in the history of waste generation in the nuclear -weap-
ons complex. The first reflected a period during which wastes
and other materials were being generated as an integral part of
the production of weapons-grade nuclear materials and compo-
nents. The period after 1989 reflected the cessation of large-
scale production of such materials and the initiation of cleanup
activities and wastes from those initiatives. Thus, even before
the truncation of data in the post-9/11 period, there were sig-
nificant issues with the comparability of the data over time.
Number and Location of Municipal Solid Waste (MSW)
Landfills—D, N
This 2003 Draft ROE indicator represents an administrative
count of landfills, rather than an amount of waste produced,
and therefore does not meet the 2008 ROE indicator defini-
tion. The indicator was replaced by a new and superior indica-
tor that tracks the quantity of municipal solid waste generated
and how it is managed.
Number and Location of RCRA Hazardous Waste
Management Facilities (partially withdrawn)—D, N
This 2003 Draft ROE indicator, by itself, represents an
administrative decision to force a cleanup, rather than an
amount of waste present or removed, and therefore does not
meet the 2008 ROE indicator definition. The data were com-
bined into a new indicator, Quantity of RCRA Hazardous
Waste Generated and Managed, which combines information
from several 2003 Draft ROE indicators.
Number and Location of Superfund National Priorities List
(NPL) Sites—D
This 2003 Draft ROE indicator represented an administrative
decision to force a cleanup, rather than an amount of waste
present or removed, and therefore does not meet the 2008
ROE indicator definition.
Number and Location of RCRA Corrective Action Sites—D
This 2003 Draft ROE indicator represented an administrative
decision to force a cleanup, rather than an amount of waste
present or removed, and therefore does not meet the 2008
ROE indicator definition.
Human Exposure and Health Chapter
Urine Arsenic Level—R
This 2003 Draft ROE indicator was based on data from EPA
Region 5 only, and is not part of the 2008 ROE Regional Pilot.
Blood Volatile Organic Compound Levels—C
This 2003 Draft ROE indicator was based on a convenience
sample whose representativeness cannot be determined or
necessarily used as a baseline for future sampling. The indica-
tor is based on detects only, so there is no reference level. Also,
volatile organic compounds are cleared from the bloodstream
rapidly (about 1 hour), so there is a significant possibility of
false negatives, considering that exposure tends to be associ-
ated with occupational and indoor settings.
Cancer Mortality—P
Childhood Cancer Mortality—P
Asthma Mortality—P
Childhood Asthma Mortality—P
The independent peer review panel recommended the
removal of the cancer and asthma mortality indicators because
trends in these indicators are less likely to be due to changes in
environmental factors than to changes in social factors such as
availability/access to healthcare.
Ecological Condition Chapter
Forest Age Class—N
While forest age class has implications for biodiversity and
ecological function, this indicator was withdrawn in favor of
indicators of forest extent and type and forest fragmentation.
Extent of Ponds, Lakes, and Reservoirs—C
This 2003 Draft ROE indicator was based on data from the
USGS National Wetlands Inventory. While these data are
based on a valid statistical sampling design, the total amount
of surface water is less than half the area of lakes, reservoirs,
and ponds greater than 6 acres in size in the USGS National
Hydrography Data Set. Until this discrepancy is resolved, the
indicator may not satisfy the ROE criteria.
Extent of Estuaries and Coastline—C
This 2003 Draft ROE indicator was based on remote sensing
data, but is unlikely to show trends unrelated to sea level rise
and changing tides, so it is not a very useful indicator for trends.
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At-Risk Native Species—C
At-Risk Native Grassland and Shrubland Species—C
At-Risk Native Forest Species—C
Populations of Representative Forest Species—C
Non-Native Fresh Water Species—C
At-Risk Native Fresh Water Species—C
At-Risk Fresh Water Plant Communities—C
The ecological condition chapter was restructured from the
2003 Draft ROE organization per the recommendation of
EPA's Science Advisory Board and numerous stakeholders. As
such, the chapter no longer requires that the above indicators
be broken out by ecosystem. In addition, the ability to track
trends of many of these indicators is questionable.
Tree Condition—C
This 2003 Draft ROE indicator was based on an ongoing
statistical sample of forests across the contiguous U.S. and
comprises components that relate to crown (tree canopy) con-
dition, the ratio of dead to live wood, and the fire class. This
indicator likely relates more to forest management practices
than to environmental condition, and for this reason has low
relevance value to EPA.
Population Trends of Invasive and Native Non-Invasive Bird
Species—R
This 2003 Draft ROE indicator was based on an analysis of
USGS Breeding Bird Survey data in grassland and shrubland
ecosystems for 5-year periods ranging from the late 1960s
to 2000. Because the ecological condition questions are no
longer directed at specific ecosystem types, this appears to be
a Regional Indicator. Also, it is not clear at this time that the
data for this indicator will be collected in the future.
Coastal Living Habitats—C
This 2003 Draft ROE indicator was based on remote sensing
data of coastal wetlands, mudflats, sea-grass beds, etc., but the
only system for which a National Indicator has been devel-
oped is coastal vegetated wetlands, which already is covered in
another indicator (the 2008 ROE's Wetlands indicator).
Shoreline Types—C
This 2003 Draft ROE indicator was based on NOAA's Envi-
ronmental Sensitivity Index. The index is based on a standard-
ized mapping approach, but coverage is not complete for large
parts of the coastline and the data in some of the atlases are
more than 15 years old. Consequently, this indicator is not
appropriate for measurement of representative, national trends.
Fish Diversity—R
This 2003 Draft ROE indicator was based on a statistical sam-
ple offish trawls in Mid-Atlantic estuaries during 1997-1998.
This indicator is not part of the 2008 ROE Regional Pilot
Project, and EPA's Environmental Monitoring and Assessment
Program (EMAP) is no longer collecting fish samples to sup-
port this indicator.
Bird Community Index—R
This 2003 Draft ROE indicator was not national in scope or
part of the ROE EPA Regional Pilot.
Forest Disturbance: Fire, Insects, and Disease—P
The independent peer review panel recommended that this
indicator be withdrawn because it was "limited in many
aspects of its coverage: temporally, spatially, and in types of
disturbance...Ecological interpretation of disturbance patterns
is difficult...For example, the lack of fire may actually repre-
sent an ecological disturbance, while fire suppression can lead
to overcrowded forests that are more conducive to insect and
disease outbreaks." The reviewers also commented that the
data were questionable and that the interdependence among
the disturbance categories could result in significant double-
counting. Finally, timber harvest was not included even
though it disturbs more acres than fires, insects, or disease.
Soil Compaction—C
Soil Erosion—C
These 2003 Draft ROE indicators are based on an ongoing
statistical sample of soils in forests across the contiguous U.S.,
but the actual indicators are based on models rather than mea-
surement. This violates a fundamental ROE protocol on the
use of models in indicators.
Processes Beyond the Range of Historic Variation—C
This 2003 Draft ROE indicator was based on an analysis of
recent Forest Inventory and Analysis data on climate events,
fire frequency, and forest insect and disease outbreaks, which
•were then compared to anecdotal data for the 1800-1850
period. Because the early data are anecdotal, and because the
data mostly relate to forest management practices, etc., it is
proposed that this indicator has low relevance to EPA and that
trend data are of questionable utility as an ROE indicator.
Soil Quality Index—R
This 2003 Draft ROE indicator was based on a survey of soils
in the Mid-Atlantic region during the 1990s; that survey was
not repeated and is not part of the Regional Pilot Project for
the 2008 ROE.
Terrestrial Plant Growth Index—P
The independent peer review panel recommended that this
indicator be withdrawn because "The results are too ambigu-
ous and not explained, or perhaps, unexplainable...NDVI is
a crude measure of growth. [Also,] The relative deviation of
the Plant Growth Index (20-40%) without explanation during
the period of analysis suggests that the indicator might lack the
precision needed to assess national trends in productivity."
Chemical Contamination (partially withdrawn)—C
This 2003 Draft ROE indicator combined data from the
NAWQA program that are not consistent in terms of sampling
frequency or analytical protocols. The part of this indicator
presenting contaminant levels in coastal fish as measured by
EMAP was moved to a separate indicator in the water chapter
of the 2008 ROE: Coastal Fish Tissue Contaminants.
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Animal Deaths and Deformities—C
This 2003 Draft ROE indicator was based on data reported by
a number of different organizations to USGS on incidences of
death or deformities in waterfowl, fish, amphibians, and mam-
mals. Trends are available only for waterfowl, and because data
reporting is voluntary rather than systematic, the data are not
adequate to determine actual trends versus trends in reporting.
Fish Abnormalities—C
This 2003 Draft ROE indicator was based on a statistical
sample offish trawls in estuaries in the Atlantic and Gulf, but
the data are no longer being collected by EMAP to support
this indicator.
Unusual Marine Mortalities—C
This 2003 Draft ROE indicator was based on voluntary
reporting of unusual mortality events to NOAA. Because
there is no systematic requirement to report, these data are not
suitable to support national trends in the indicator.
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