s>EPA
EPA/600/R-14/212 I July 2014 I www.epa.gov
United States
Environmental Protection
Agency
Cumulative Risk Webinar Series
WHAT WE LEARNED
Office of Research and Development
National Center for Environmental Resear
Office of the Science Advisor
Risk Assessment Forum Cumulative Risk Tec
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&EPA
EPA/600/R-14/212 I July 2014 I www.epa.gov
United States
Environmental Protection
Agency
'"•"l I
Cumulative Risk Webinar Series
WHAT WE LEARNED
by
Devon C. Payne-Sturges and Lawrence Martin
Office of Research and Development Office of the Science Advisor
National Center for Environmental Research Risk Assessment Forum Cumulative Risk Technical Panel
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ontents
List of Acronyms v
Acknowledgments vii
Cumulative Risk Webinar Series: What We Learned 1
August 29, 2012: Nonchemical Stressors and Cumulative Risk Assessment—
An Overview of Current Issues and Initiatives 4
September, 26, 2012: Characterizing Cumulative Air Pollution Risks 5
October 17, 2012: Cumulative Environmental Vulnerability Analysis—
Opportunities for Innovation 7
November 28, 2012: Assessing the Health Impact of Multiple
Environmental Chemicals 8
December 19, 2012: Cumulative Levels and Effects—Implementing a
Unique Environmental Justice Statute in Air Permitting in Minnesota 10
January 30, 2013: Integrating Susceptibility Into Environmental Policy—
Implications and Information Needs for Cumulative Risk Assessment 12
February 27, 2013: The Patterns of Pollution—Perspectives From an
Environmental Attorney and a GIS Scientist on the Identification and
Assessment of Environmental Justice Communities 14
March 20, 2013: A Semi-Quantitative Framework for Cumulative Risk
Assessment of Waterborne Contaminants 17
April 17, 2013: Simulating Population Characteristics and Exposures to
Multiple Stressors for a Community-Based Cumulative Risk Assessment 19
May 22, 2013: Why and How to Integrate Your Assessment 21
June 26, 2013: A Novel Approach for Testing Interaction Effects of
Environmental and Psychosocial Stressors on Disease Risk in a Logistic
Regression Model 23
July 24, 2013: CalEnviroScreen 1.0—A New Tool for Evaluating
California Communities 25
September 25, 2013: Legal Authority forEPAto Use Cumulative Risk
Assessments in Environmental Decision Making 26
November 20, 2013: Implementation of Cumulative and Mixtures Risk
Assessment in the Office of Water—Past and Future 28
December 11, 2013: Challenges in Making Risk Assessment More Relevant
for Risk Management—A View From the European Union 30
Webinar Dates and Recordings 32
Supplemental Materials 34
Appendix. Select Statutory Provisions Regarding EPA Authority to Consider Risk 37
Endnotes... ...42
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ist of Acronyms
ADHD attention deficit hyperactivity disorder
ALT alanine aminotransferase
AOP adverse outcome pathway
BenMAP Environmental Benefits Mapping and
Analysis Program
CAA Clean Air Act
CAD DIS Causal Analysis/Diagnosis Decision
Information System
Cal EPA California Environmental Protection Agency
CCL Contaminant Candidate List
C E HI Cumulative Environmental Hazards Index
CERCLA Comprehensive Environmental Response.
Compensation, and Liability Act
CEVA Cumulative Environmental Vulnerability
Analysis
CR concentration response
CRA cumulative risk assessment
CSAP R Cross-State Air Pollution Rule
CWA Clean Water Act
DALY disability adjusted life year
D B P disinfection byproduct
EJ environmental justice
EPA Environmental Protection Agency
EU European Union
FDCA Federal Food, Drug, and Cosmetic Act
Fl FRA Federal Insecticide, Fungicide, and
Rodenticide Act
FQPA Food Quality Protection Act
GIS geographic information system
HAP hazardous air pollutant
HOM E Home Observation for Measurement of the
Environment
IRIS Integrated Risk Information System
I VAN Imperial Visions Action Network
M C L maximum contaminant level
MCLG maximum contaminant level goals
M PCA Minnesota Pollution Control Agency
NAAQS National Ambient Air Quality Standards
NAFLD nonalcoholic fatty liver disease
MAS National Academy of Sciences
NATA National Air Toxics Assessment
NCA Neighborhood Council of Advisors
N C EA National Center for Environmental
Assessment
N C E R National Center for Environmental Research
NCP National Contingency Plan
NDEA N-Nitroso-N-Diethylamine
NDMA N-Nitrosodimethylamine
NESHAP National Emissions Standards for Hazardous
Air Pollutants
N H AN ES National Health and Nutrition Examination
Survey
N02 nitrogen dioxide
N P DWR National Primary Drinking Water
Regulations
NSPS New Source Performance Standards
OAR Office of Air and Radiation
0 E H H A Office of Environmental Health Hazard
Assessment
0 R D Office of Research and Development
OW Office of Water
PCB polychlorinated biphenyl
PM2.s fine paniculate matter
QALY quality adjusted life year
RAF Risk Assessment Forum
R E AC H Registration, Evaluation, Authorization and
Restriction of Chemicals
Rf D reference dose
S DWA Safe Drinking Water Act
SES socioeconomic status
STAR Science To Achieve Results
SVI Social Vulnerability Index
T M D L total maximum daily loads
UIC underground inj ection control
USDHHS U.S. Department of Health and Human
Services
USEPA U.S. Environmental Protection Agency
VOC volatile organic compound
WQS Water Quality Standards
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The CRA Webinar Series would not have been possible without the support of several people.
First, we would like to thank our CRA Webinar Series coordinator, Ms. Ashley Bubna*, for her
agility and resourcefulness and for always thinking ahead. We would like to acknowledge support
from members of the NCER communications team, Kelly Widener, Ryann Williams*, Kathi
Wiser and Myles Morse. Last, we would like to thank our speakers and all the CRA Webinar
participants for the wonderful exchange of information and open dialogue.
* Student Services Contractor
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WHAT WE LEARNED
by
Devon C. Payne-Sturges1 and Lawrence Martin2
The Cumulative Risk Webinar Series was presented
to examine and stimulate discussion of topical issues
important to advancing cumulative risk assessment
(CRA). The U.S. Environmental Agency's (EPA)
National Center for Environmental Research (NCER)
is funding extramural research to develop methods
and strategies for assessing the combined effects of
chemical, physical, biological and social stressors
while factoring in population vulnerabilities (see http://
www.epa.gov/ncer/cra/). EPAs Risk Assessment
Forum (RAF) is developing Agency guidelines for
CRA, building upon the existing methods for chemical
mixtures risk assessment routinely employed by EPA
programs and regions. Because of our common interest
in advancing the science on cumulative risk, NCER and
the RAF Cumulative Risk Assessment Technical Panel
collaborated to host the webinar series, which ran from
August 2012 through December 2013. Presentations
were chosen for their innovative research on cumulative
risk, particularly quantitative and qualitative methods
and analytical strategies for examining combinations
of multiple chemical, physical and biological stressors,
as well as how to factor in population vulnerabilities,
including socioeconomic stressors.
The webinar series presented 15 public webinars
between August 2012 and December 2013. The series
featured scientists from both inside and outside EPA,
including Science to Achieve Results (STAR) grantees
funded by EPA, who discussed the development of
cumulative risk analysis methods, including methods
for incorporating "nonchemical stressors." The CRA
Webinar Series was open to the public to stimulate wide
discourse on cumulative risk themes. The audience
was broad and included representatives from academia,
industry, state and local environmental and public health
agencies, nonprofits, consulting firms, community-
based organizations and environmental justice (EJ)
organizations. Each webinar had between 100 and 250
participants. Archived recordings of each webinar can
be found on NCER's website. (See Webinar Dates and
Recordings, below, for a directory of webinar titles and
links.)
Addressing multiple exposures to chemical and
nonchemical stressors and cumulative risks and impacts
in environmental decisions has long been a challenge for
risk assessment and has concerned communities and EJ
organizations. The webinar series identified a number
of key science and science-policy issues for advancing
the practice and utility of CRA, which are summarized
below.
Complexity of the Concepts and Definitions
for Vulnerability and Nonchemical Stressors
Stressful social environments may make a population
that is already subject to chemical stressors even more
sensitive to unhealthy environment exposures. Extensive
studies show associations between disadvantaged
communities and suboptimal health. Because of the push
for CRA to include social stressors (also commonly
referred to as "nonchemical stressors"), epidemiological
studies are becoming very important and receiving
greater emphasis in CRA as an approach to assessing the
relative contribution of different stressors, and potential
interactions between chemical and social stressors. The
August 2012 webinar speaker, Ari Lewis, provided
excellent definitions and conceptual frameworks for
vulnerability. She also provided examples of how, within
each of the four traditional risk assessment steps, CRA
could move beyond screening assessments and include
vulnerability and social stressors.
Epidemiological Methods, Effect Modifiers,
Dose-Response Curves
More evidence is emerging that social conditions may
amplify the effect of environmental agents on health
and can contribute to health disparities. These social
conditions may be quantitatively incorporated in
1 Devon C. Payne-Sturges, U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environ
2 Lawrence Martin, U.S. Environmental Protection Agency, Office of the Science Advisor, Risk Assessment Forum
[mental Research
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cumulative risk assessment as effect modifiers in the
dose-response assessment if data exist to support this
relationship. The September 2012 webinar speaker.
Neal Fann, presented an approach that showed that
educational attainment, a marker of socioeconomic status
(SES), modified the relationship between fine paniculate
matter (PM2 5) and mortality: Lower educational
attainment is associated with higher PM2 5 mortality risk.
The January 2013 speaker, Dr. Ramya Chari, presented
results of her research in which she replicated the risk
assessment approach used by EPA in 2008 to revise the
National Ambient Air Quality Standards (NAAQS) for
lead, except Dr. Chari incorporated information from
published studies that indicated lead health effects
vary across socioeconomic position. Her results were
startling: Children from low SES families are impacted
more in terms of estimated IQ loss than are children
from higher SES families who receive the same level of
air lead exposure.
Statistical Models (Biomonitoring,
Microdata, Logistic Regression)
Statistical models may be applied in a variety of
ways to evaluate cumulative exposures and risks. The
November 2012 speaker, Dr. Krista Christensen.
demonstrated a regression model based on National
Health and Nutrition Examination Survey (NHANES)
biomonitoring data that could predict the effects on
common health endpoints. She felt the best use of
this statistical approach (logistic) would be for dose-
response assessment for multiple stressors. CRA at
community levels is challenged by the availability of
relevant exposure and health data at the appropriate
geographic scale. The April 2013 webinar STAR grantee.
Dr. Jonathan Levy explained his use of regression
models to generate a data set based on samples from
a subset of individuals in the community—simulated
annealing. He validated his model against state-level
survey data. A statistical approach being developed
seeks to overcome the limitations of traditional effect
modification or interaction terms in regression equations
and models. During the June 2013 webinar, Dr. Wenyaw
Chan, also a STAR researcher, provided an overview
of a new logistics regression framework to assess the
combined effects of environmental and psychosocial
stressors on hypertension. The psychosocial stressors
that will be included in the model are identified through
the community-based participatory research component
of the project led by Dr. Chan's colleague, Ms. Maria
Jimenez.
Mapping and Screening for Cumulative
Burden (Indices)
We learned about the utility of several mapping and
screening tools for cumulative community impacts/
burden: Cumulative Environmental Vulnerability
Analysis (CEVA) methodology (October 2012,
Dr. Jonathan London); an EJ mapping tool developed
for metropolitan Atlanta (February 2013, David
Deganian and Nick DiLuzio); and the California
Environmental Protection Agency's (CalEPA)
CalEnviroScreen (July 2013, Dr. GeorgeAlexeeff).
These speakers demonstrated how geographic
information system mapping of multiple pollution
sources (all based on publically available data sets)
overlaid with demographics information can help to
identify locations with high environmental hazard
burdens. The CalEnviro Screen and CEVA tools go
further by incorporating indicators of population
vulnerability and nonchemical stressors. Each speaker
also championed the importance of community
involvement and engagement in the development
of these mapping tools and in the translation of the
results. Dr. Alexeeff stated that extensive community
engagement was conducted to identify key pollution
sources or concerns, as well as which health and social
indicators to include in CalEnviro Screen. Mr. Deganian
and Mr. DiLuzio noted that their EJ mapping tool for
Atlanta served as a public engagement vehicle, helping
to educate residents about their neighborhoods. Although
these mapping approaches for cumulative burden can
be quite sophisticated, they are suitable for screening
geographic locations for cumulative impacts and
identifying overburdened populations or communities.
These approaches can help regulatory and public health
agencies better describe communities (conditions and
vulnerabilities) that are potentially affected by pollution
and help prioritize where regulatory action might be
needed, versus using the screening tool to set standards
or show causation of health effects.
Legal/Decision Frameworks
Webinar participants frequently asked (in the post-
webinar evaluations) for information on decision
frameworks for CRA. Risk assessors are concerned
that CRA requires considering every possible stressor
in the assessment, which seems daunting. Others are
concerned about statutory authority for using CRA
in decision making. Other complicated scenarios for
applying CRA include cases where the objective is to
apportion responsibility among parties (polluters) for an
existing pollution problem, such as a hazardous waste
site. Four webinar speakers addressed the use of CRA in
decision making. The most concrete example of using
cumulative analysis in a regulatory decision making
context was Minnesota's new air permitting statute.
Minn. Stat. § 116.07, subd. 4a), which applies only to
the South Minneapolis area. As the December 2012
speaker, Dr. Kristie Ellickson, described, under this
law, the Minnesota Pollution Control Agency first must
"analyze and consider cumulative levels and effects"
before it issues permits in the affected area. The law does
not use the terms "cumulative impacts" or "cumulative
risks," but it does include all pollutants, environmental
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media, sources, and time periods and receptors. A federal
statutory perspective on using CRA in decision making
was presented in the September 2013 webinar by Sarah
Alves and Joan Tilghman. We learned that Congress
has intentionally addressed environmental pollutants/
problems on a piecemeal basis (pollutant-by-pollutant).
Congress also deliberately writes statutes broadly so that
EPA can implement them more effectively over time.
Furthermore, the statutes do impose a general provision
on the Agency to "protect public health," which could
open a window to apply cumulative risk in a decision.
Even if a court finds that an environmental statute with
a broad mandate to protect public health gives EPA
discretion to consider CRA, the Agency must be able to
demonstrate that (1) its CRA methodology and its use of
the results are scientifically reasonable (i.e., appropriate
use of data and assumptions) and (2) that it considered
all factors required by the statute.
EPA often supports or justifies its decision making by
estimating the risks associated with various pollutants
or stressors, although not every statute specifies using
risk assessment (see Appendix). Although the value and
relevance of risk assessments have been questioned.
the National Research Council asserts in its report
Science and Decisions: Advancing Risk Assessment
that risk assessment remains an appropriate method for
measuring the relative benefits of the many possible
interventions available to improve human health. Our
January 2013 webinar speaker, Dr. Tom Burke, who
was one of the authors of Science and Decisions, spoke
to the future direction of risk assessment, including the
need to harmonize cancer and noncancer approaches
(that is, move away from reference doses) and to make
the CRA process more scenario-based and iterative.
so that decisions about which stressors to include in a
CRA target those stressors for which closer analysis
might benefit risk-management decisions most
clearly. Dr. Burke stated, "To orient the [CRA] around
risk management options is the approach that we
recommended so that we focus on the stressors under
consideration." This dove-tailed with the European
Union view presented by Dr. Peter Calow, our
December 2013 webinar speaker, who noted that one of
the major challenges is to make risk assessment more
relevant for risk management—that is, "more value-
relevant" or relevant to public preferences. This must
be done in a way that is transparent and avoids political
interference with the science.
Differing Meanings of CRA/Use of Terms
(Impacts, Risks, Levels, Effects)
For each of our webinars, we conducted a participant
survey. Respondents shared their definitions of
cumulative risk and cumulative impacts. Not surprisingly
the definitions varied, as shown in the following
examples:
Cumulative means—
• The risks to/effects on human health over time when
exposed to multiple contaminants.
• It is a holistic understanding of health risk,
including environmental agents (chemical,
biological, radiation) as well as socioeconomic
factors.
• It means pushing the envelope on risk assessment
beyond the "chemical-by-chemical" concentration
measures to instead measure effects/endpoints/
adverse outcomes.
• The combination and effects of multiple
contaminants from multiple sources through
multiple exposure pathways.
• The combined effects of multiple chemicals from
multiple exposure pathways should be taken very
seriously by the regulators.
• "Cumulative risk" involves the summation
of exposure hazards for human or ecological
populations to multiple environmental stressors.
• The risks that individuals and communities face as
a result of all of the different risk factors they may
have (social, economic, occupational, genetic, ...).
• The aggregate risk to either humans or the
environment, taking into account multiple endpoints,
as well as multiple contributing risk factors or
contaminants.
• Understanding multiple stressors in a community
context.
• As an environmental epidemiologist...everything.
Some people think that there should be one definition for
"cumulative," while others can accept a broad definition
or multiple definitions that can be implemented in
varying ways to fit the particular situation. The important
message is that perhaps the assessment or evaluation
of cumulative does not necessarily mean we must
arrive at one number. "Cumulative" can be described
in multiple ways—as impacts, levels, risks and effects.
both quantitatively and qualitatively—and still inform a
decision.
It is our hope, through presenting this summary of the
CRA Webinar Series, that EPA and its stakeholders will
be inspired to continue the effort to move away from
an approach that assesses the impact of one source.
one agent on the average person toward the use of
environmental and environmental health assessments
and evaluations that better reflect reality, especially
when setting policy and making regulatory decisions. It
is possible, and our speakers presented on a number of
tools and approaches to make CRA possible.
In the following Sections you will find summaries of
each CRA webinar, links to archived recordings of each
webinar by date and links to supplemental materials and
background papers provided by each of our webinar
speakers.
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Webinar 1
August 29, 2012
Npnchemical Stressors and Cumulative
Risk Assessment—An Overview of
Current Issues and Initiatives
Ari S. Lewis, M.S., Environmental Health
Principal Scientist and Toxicology Team
Manager at Gradient/Environmental
Consulting
The speaker, a toxicology and risk assessment expert
with particular expertise in toxic metals, described
the current state of cumulative risk assessment (CRA)
science. Her talk focused on three learning points.
described below.
1. Potential vulnerabilities in populations
and their consideration in cumulative
health risk assessment
CRA's inclusion of social stressors—defined as "acute
or chronic events of psychological or social origin
that challenge the homeostatic state of biological
systems"—clearly has linked CRA and environmental
justice (EJ). Both share the overall goal of identifying
health disparities among vulnerable communities and
identifying the chemical and nonchemical stressors to
target for intervention. Stressful social environments
may make populations that potentially already carry a
disproportionate chemical exposure burden even more
sensitive to chemical exposures. Extensive studies show
associations between disadvantaged communities and
suboptimal health.
Income insecurity, racism, family instability and a
violent community or home are among the psychosocial-
related stresses potentially interacting with innate
biological characteristics and an increased chemical
burden from old, substandard housing, poor ventilation.
traffic density and other sources. It would be useful for
EPA to comprehensively list such putative psychosocial
vulnerabilities. Natural disasters, such as Hurricane
Katrina, would be included on the list because the
general principle is that stress affects how chemicals
interact with biological systems. That principle is
supported by animal studies that provide information on
potential interactions.
2. Key facets of chemical risk assessment
and how those issues inform efforts
to advance the field of CRA, including
consideration of the most significant
challenges involved with incorporating
nonchemical stressors
CRA needs to understand and quantify the extent
to which current risk assessment methods capture
nonchemical stressors and account for vulnerabilities.
Research is needed, for example, to understand what
the intraspecies uncertainty factor does not capture.
Underlying criteria need to be studied for vulnerable
populations.
Considering chemical exposures and psychosocial
vulnerabilities in a single metric is complex. It is
extremely difficult to express a nonchemical "dose,"
which involves different metrics. Initial steps have
focused on screening tools to identify communities
with the greatest vulnerabilities. Indicators include
social demographics, pollution exposures and public
health indices that are used to semi-quantitatively
rank communities, with the goal of identifying at-risk
communities to target for more refined analysis.
A critical question for CRA is how science can measure
exposure to social stressors. Biomarkers can provide a
way to measure "allostatic load," a useful concept that
refers to "the physical consequences of chronic exposure
to fluctuating or heightened neural or neuroendocrine
response that results from repeated or chronic stress."
Examples are measurements of cortisol and epinephrine
as biomarkers of neuroendocrine effects and of blood
pressure and heart rate as biomarkers of cardiovascular
effects. The concept captures the complexity of
psychosocial stressors and interactions between chemical
and nonchemical stressors. Any valid biomarker would
be beneficial.
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3. An overview of the research and
approaches currently being explored to
characterize cumulative risks, including
mechanistic research, epidemiological
evaluations and risk-ranking tools
To move beyond screening assessments requires an
understanding of the increasingly complex interactions
between multiple chemical and nonchemical stressors.
Understanding the relative contribution of nonchemical
and chemical stressors using the full array of epidemio-
logical, animal and in vitro studies will inform both types
of risk assessments. Animal and mechanistic research is
less relevant for nonchemical stressor research, but it can
provide important mechanistic information on interac-
tions, as with the case of rat studies indicating the joint
effect of lead exposure and stress on health outcomes.
Mechanistic research also can help identify relevant
biomarkers.
Epidemiology is receiving greater emphasis in CRA
as an approach to assess the relative contribution of
different stressors and potential interactions between
chemical and nonchemical stressors. There is great
potential in mining existing data, even if the data are in
unsuitable form. In many epidemiologic studies stress
is considered a confounder. The question can be asked:
How did correcting for a social indicator change the
results? Such analysis is not straightforward, and the
contribution of socioeconomic status differs by endpoint.
Hypothetical examples illustrate how in each of the
four traditional risk assessment steps CRA could move
beyond screening assessments. For hazard assessment.
for example, a science-based list of stressors for each
endpoint could be used to assess which community
stressors contribute to particular health disparities. All
the chemical, social, biological and physical stressors
affecting a given endpoint, such as respiratory disease.
would be listed. For exposure assessment, powerful
geographic information system (GIS) -based databases
can be used to predict community exposures; some
indicators using this approach are less reliable for
individual exposure assessments (e.g., the presence of
brownfields, hazardous waste sites, etc.). These tools
are powerful for organizing data and investigating
associations, but they cannot be used to quantify risk
absolutely, do not measure biological indicators and have
other limitations. Validation is needed of the most useful
indicators for approximating community and individual
exposures and health. Science needs to determine how
well traditional risk assessment reflects the spectrum of
susceptibilities in a population, and—where required—
more holistic approaches will have to be implemented.
Ms. Lewis was asked about epigenetic changes, or
changes in gene expression, as a possible biomarker
for stress. She replied that it is unclear if the concept is
biologically sound; how one would measure epigenetic
changes in people is a key question. If research
supported using such a biomarker, however, that
could be a powerful tool. A recent study suggests that
neighborhoods have different, measurable epigenetic
imprinting.
Webinar 2
Characterizing Cumulative Air Pollution
Risks
Neal Fann, EPA, Office of Air and Radiation
(OAR)
The speaker, a policy analyst with expertise in
estimating the economic and health benefits of air
pollution management options, described how OAR
is moving incrementally toward adopting cumulative
risk approaches in place of its traditional pollutant-by-
pollutant risk reviews. His talk focused on three learning
points, as follow.
1. How EPA estimates the human health
impacts of air quality changes
OAR is concerned with reducing a variety of health
impacts from air pollutants, including premature death
and asthma attacks. To that end, EPA must be able to
monetize the health impacts from air pollutants using the
best available studies in the scientific literature. BenMAP
(Environmental Benefits Mapping and Analysis Program)
is EPA's principal tool for monetizing the benefits of
air quality improvements by estimating the incidence
and economic value of adverse health outcomes using
population and air quality data. Full multi-pollutant
BenMAP software is available at the EPA website: http://
www.epa.gov/airquality/benmap/index.html. Establishing
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a baseline risk is key because all of the other risk
estimates are relative to that benchmark.
One example of how OAR monetized health impacts
and benefits is the regulatory impact analysis of the
Agency's 2014 Cross-State Air Pollution Rule (CSAPR)
addressing fine paniculate matter (PM2 5) and ozone
pollution. The analysis is not truly multi-pollutant;
rather it uses studies that control for other pollutants as
potential confounders.
2. The extent to which EPA can estimate
the cumulative human health risks of air
pollution with current methods and data
The health impact assessment for the CSAPR accounts
partially for cumulative exposure, differential
susceptibility and other factors critical to CRA, and it
represents OAR's best effort to account for multiple
pollutants to date. As a step toward performing a full-
scale CRA, after first estimating the avoided deaths
and illnesses expected to result from implementing
CSAPR, the analysis next characterized the distribution
of these avoided deaths among population subgroups.
including those most susceptible to air pollution effects.
Using BenMAP, OAR characterized the percentage of
all-cause deaths attributable to PM2 5 in 2005 in each
county; this established a baseline distribution of risk.
against which the authors compared the distribution
of risk in 2014, when the rule was to be implemented.
The analysis illustrated that the number of counties at
or above the median 2005 risk level fell significantly
by the 2014 baseline (i.e., before the CSAPR rule was
implemented, but after air quality policies affecting other
sectors reduced emissions): from 1,505 in 2005 to 958 in
2014. After CSAPR was implemented, the number fell
further to 180. Although focused on PM2 5, the analysis
could easily be applied to ozone. EPA is transitioning
from characterizing only the overall health impacts a rule
avoids to assessing the overall impacts from PM2 5 and
ozone reductions, how the impacts are distributed over
space, and how different populations (such as children
and adults) are affected, thereby incrementally moving
toward CRA.
3. Promising new approaches for
characterizing the cumulative impacts of
multiple pollutants and stressors
Mr. Farm presented graphs assessing education-modified
PM2 5 mortality risk in the 2014 CSAPR. Two long-
term epidemiological studies found that education status
modifies PM2 5 exposure and risk. The reasons for the
effect are unclear. An analysis showed that in 2005.
populations without a 12th-grade education faced greater
vulnerability to air pollution than other populations.
This was demonstrated by a different dose-response
curve for low educational attainment. Among the
high-risk populations in the CSAPR analysis, the risk
falls precipitously; among the lower risk populations.
the studies still show a benefit from the CSAPR, but
not as large. By the time the 2014 rule is in place, the
risks begin to equalize. This is an incremental step
toward CRA because it is focused on more vulnerable
populations.
The speaker described a Detroit project that explored
a multi-pollutant risk reduction approach based on air
quality management for the city, focusing on vulnerable
and susceptible populations. The project characterized
population susceptibility using both mortality rates and
rates of hospital admissions for asthma. It demonstrated
that to achieve maximum air quality benefits, a multi-
pollutant approach delivers the most gains, no matter
how "vulnerable and susceptible populations" are
defined. EPA also has been asking how it can better
express the joint, combined risk from conventional air
pollution and air toxics, given that the differences in
how those risks are estimated make them challenging to
combine. As a draft proof of concept, OAR plotted the
distribution of PM2 5 mortality risk across the United
States from directly emitted PM2 5 and the cancer risks
from metal air toxics. After plotting the risks, OAR
identified the upper 80th percentile for both distributions.
a first step for characterizing joint, cumulative risk across
both pollutants and one that represents a potentially more
comprehensive approach for the future.
Lastly, the speaker described an OAR attempt to estimate
temperature-modified ozone mortality. EPA has not
traditionally considered how temperature can modify
health effects, and the science is still developing, so there
is no definitive information.
During the question-and-answer session, Mr. Farm was
asked: "Inyour 'cumulative risk'analysis, you seem
to still be doing every pollutant individually and then
adding risks or looking at percentile:s. What seems
missing here is an analysis of the joint effect of being
exposed to both. What does it mean to be exposed to
both metals andPM, for example?" He responded that
EPA is making the best use it can of the epidemiological
literature that is applicable for air pollution risk
assessments. A developing body of research is looking
at joint impacts of multiple pollutants, but it is very
challenging. When EPA created the maps expressing the
overlap between the risks from conventional pollutants
and air toxics, the approach did not provide a total point
estimate of risk and is therefore unsatisfying. If the
prior belief is that being exposed to PM2 5 and metal air
toxics is undesirable due to a potential for synergism.
an air quality manager would want to know that. "What
elements in air pollution contribute to diabetes?"
Populations with pre-existing chronic conditions.
including diabetes, may be more susceptible to air
pollution-related impacts than the general population.
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Webinar 3
October 17, 2012
Cumulative Environmental Vulnerability
Analysis—Opportunities for Innovation
Dr. Jonathan London, University of
California, Davis, and Center for Regional
Change (CRC)
The speaker, an Assistant Professor in the Department of
Human Ecology and Director of the CRC, has an interest
in conflict and collaboration in natural resource and
environmental issues, with an EJ focus. He introduced a
hazard and vulnerability screening method, including the
social and institutional context through which the tool
was developed. His talk focused on three learning points.
described below.
1. An introduction to the science
behind the Cumulative Environmental
Vulnerability Analysis (CEVA)
methodology
CEVA is a screening tool to help better target funding.
monitoring, permitting and enforcement in the most
vulnerable EJ communities. The methodology, which
is a work in progress, was developed in an "engaged
setting" working with communities. It helps to identify
communities that have a relatively higher ranking using
the combination of two key indices: the Cumulative
Environmental Hazards Index (CEHI) and the Social
Vulnerability Index (SVI), with health and other criteria
layered into the resulting maps. CEHI indicators include
such measures as pesticide applications, cancer risks
from inhaled toxics and water quality assessments;
SVI measures include the sensitivity of receptors (for
individuals younger than age 5 or older than age 65) and
the availability of social and economic resources to take
action in the face of environmental concerns, such as the
percentage of a community's population older than age
25 without a high school diploma or who do not speak
English very well. Health status is a separate indicator.
but it might be merged into the SVI. Land use, transit
and other factors are not in the indices, but they are
considered as additional screening issues.
Important distinctions exist between the terms "risks,"
"impacts" and "vulnerability," although they are related
concepts. Risks refer to the magnitude and likelihood
of impacts, which are a measure of effect; vulnerability
refers to the relative sensitivity of certain populations
and individuals to the risks that might cause more of an
impact or a greater likelihood of an impact.
The CEVA index is created by combining all of the
indicators into a single multi-indicator CEHI/SVI index.
A census tract's CEHI/SVI indicators are classified by
relative severity using the highest 20 percent of values in
the High (H) category, middle 60 percent of values in the
Medium (M) category, and lowest 20 percent in the Low
(L) category. On a color-coded, numbered nine-cell grid.
results are categorized, starting with the first cell for low-
vulnerability tracts that have L/CEHI; L/SVI, moving
up to the ninth cell for high-vulnerability tracts having
H/CEHI; H/SVI, with all combinations in between. The
highest three cells are selected as "CEVA Action Zones."
The results are mapped by census tract to show "red" for
action zones and other colors for less vulnerable tracts.
Tribal lands and other factors are layered onto maps to
create a visual display of neighborhood differences in
cumulative environmental vulnerability.
2. Enhanced understanding of the
collaborative processes that supported
the development of the CEVA
CEVA employed "community mapping" to inform and
empower local residents' advocacy for improving their
vulnerable communities. In workshops, communities
and CEVA partners marked up large-scale aerial maps
to identify "hidden hazards," potentially harmful
sites not accounted for in government databases for
various reasons. CEVA digitized the maps and layered
community-identified sites over some of the base maps.
In addition, the Imperial Visions Action Network (IVAN)
interactive website was used for "crowdsourcing,"
allowing residents to call or type in reports of hazardous
waste or other environmental problems.
3. Innovative ideas for applying CEVA and
other cumulative impact methods to
inform and improve public policy
Several CRA-related initiatives in California over the
past 5 years have employed CEVA-like innovations
that could be explored for possible integration. The
California Environmental Protection Agency (CalEPA)
Environmental Justice Screening Method, for example.
uses "land use polygons" to hone in on populated areas
with hazardous and toxic sites and has been used for
such policy initiatives as "Green Zones" and "Solar
for All." CalEnviroScreen, now under development by
CalEPA, employs wide data sets for statewide coverage.
EPA Region 9 (serving the Pacific Southwest) and the
California Governor's Office of Planning and Research
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are comparing these and other methods to address
concerns about duplicative efforts.
The speaker described several concerns that have
been raised about CRA and related assessment tools.
including CEVA, and outlined recommendations for
how to avoid them. For example, one concern is the
potential for government agencies to undergo paralysis
by "infinite analysis." This can be addressed if screening
tool developers provide explicit descriptions of what job
the tool is designed to do and set thresholds for when
analysis should end and action begin.
A participant commented that CEVA does not appear to
rank the significance of stressors or social vulnerability.
Dr. London responded that for pesticides and point-
source emissions sites, a ranking of sorts was conducted.
For example, the pesticides included in the screening
tool are the most toxic and those with the greatest
likelihood of having fate and transport data to help define
exposure potential. For water quality, the six chemicals
of greatest concern were selected, but CEVA did not, for
example, rank arsenic as more important than chromium
VI. The fact of inclusion of the chemicals was an
implicit ranking of importance. Waste sites were scored
based on various criteria, such as whether the site was
open or closed and the types of wastes processed.
Another questioner noted that with CEVA a lot of
different information gets the same rank, and trying to
combine more than two criteria is risky. The speaker
responded that there is a trade-off when developing
multi-indicator matrices. As an analogy, a driver having
to track 50 dashboard indicator dials would either
crash or ignore them. CEVA combines data to focus on
the two indicators of environmental hazard and social
vulnerability and must recognize the trade-offs and
make the limitations clear. CEVA communicates to
stakeholders that the tool is for screening, not for risk
assessment, and is finding better ways to develop an
understanding of the implications of that distinction.
Noting that CEVA adds many different hazards
together that do not all translate equally to risk and
then categorizes indicators by L/M/H, a questioner
asked: "Have you done any weighting? " Also, "Does
this correlate with vulnerability or risk in real life,
or is it just an indexing exercise you think might be
related to vulnerability or risk? " Dr. London responded
that weighting can be arbitrary; it is place-based, and
deciding what is most important to a place is a value
judgment. In addition, it is a much more complex
process to analyze the lexicological and epidemiological
data source by source; CEVA is a screening assessment.
It is called "risk," but it is not risk in the regulatory
sense, in which a risk estimate is produced; it only
identifies places with a relatively higher profile
of risk phenomenon. CEVA is a way of adopting
the precautionary principle and understanding the
possibilities of risk and the potential magnitude of those
harmful events and conditions.
Webinar 4
November 28, 2012
Assessing the Health Impact of Multiple
Environmental Chemicals
Dr. Krista Christensen, National Center for
Environmental Assessment (NCEA)
The speaker, an epidemiologist in NCEA's Quantitative
Risk Methods Group, has conducted research on
environmental chemical exposures and impacts on
children's health and pubertal development; she also
has worked on Integrated Risk Information System
(IRIS) chemical assessments for asbestos, phthalates.
poly chlorinated bipheny Is (PCBs) and beryllium. Her
talk focused on three learning points, as follow.
1. What is CRA, and what are some
methodological challenges when
attempting to examine the effect of
many environmental chemicals in
relation to a health outcome?
Noting that CRA is a burgeoning area of research and
interest that seeks to include all significant risk factors
in an analysis, the speaker described key methodological
challenges that a cumulative risk assessor might
encounter. The first is "dimensionality," which refers to
the possibility that the many risk predictors encompassed
by a CRA might far outweigh the data available on them.
limiting the assessment's statistical power. The second is
the "multiple testing" issue, which refers to the increased
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likelihood of false positives when many statistical tests
are performed for a multifaceted CRA. Using exposure
as a specific example, the speaker stated that exposures
are likely to have very different ranges and metrics.
making it difficult to gauge the relative contribution
of the different exposures (e.g., chemicals in air and
water, biomonitoring data and such factors as household
income). Lastly, the most commonly cited CRA
challenge is how to handle and evaluate the relationships
among risk predictors. Relationships can include
biologically and statistically formed relationships, such
as collinearity, correlation and confounding. Given
the challenges, traditional statistical methods may
be inadequate for CRA. The speaker reviewed four
specific statistical methods proposed for CRA and their
limitations: regression models, discriminate analysis.
cluster analysis, and principle component analysis.
2. Overview of a new statistical approach
to examine the effect of many
environmental chemicals in relation to a
health outcome
Responding to the limitations of the four statistical
approaches for simultaneously assessing many risk
predictors, Dr. Christensen worked on refining a method
for assessing multiple classes of chemical exposures
using NHANES data for the major public health
problem of nonalcoholic fatty liver disease (NAFLD).
She used elevated levels of the liver enzyme alanine
aminotransferase (ALT) as an effect metric.
3. Example of implementing this new
approach using publicly available data
Employing standard epidemiologic models and
NHANES data, she first generated 37 different
models, each with demographic covariates and one
chemical, which were later reduced to six models.
one for each chemical class. Because of limitations
with the initial modeling, the speaker focused on
the new proposed approach, called "comprehensive
analysis." The approach assigned weights to the 37
chemicals, constrained the weights to add up to 1 and
used nonlinear programming to generate a table that
ranked each chemical analyte according to its relative
"importance" in explaining an association with the risk
of elevated ALT/NAFLD. Metals and phenols were
significantly associated with elevated ALT risks, but it
remains unclear which chemicals within the class are
driving the association.
Dr. Christensen reviewed the results of the
comprehensive analysis and discussed how it addresses
the methodological challenges she had discussed
earlier. To address dimensionality, a single variable
is created—the "weighted sum"—representing the
multiple risk predictors (i.e., 37 chemicals). To address
multiple testing, the speaker used only one model that
simultaneously estimated both the weights themselves
and the other model parameters; to address different
exposures and metrics, the method used quartile
indicators (e.g., low, medium, higher, highest exposure).
not direct concentration. This makes relative contribution
easier to discern.
Asked how the comprehensive analysis might fit into
EPA's efforts to develop CRA guidelines, the speaker
said that the method would be useful as a screening
approach for the hazard identification and dose-response
steps; risk characterization will require further develop-
ment. A questioner asked, "What is the justification for
using addition if the parameters have different metrics
as you kind of alluded to? " Dr. Christensen replied that
using quartile indicators seems a "decent way to look
at the contribution of each chemical without having to
necessarily go into all the details," such as one chemical
being measured in nanograms per gram lipid and another
in terms of creatinine.
One participant commented, "Particularly when
dealing with liver disease, without knowing anything
about timing of exposures, these associations could
simply represent changes in metabolic capacity and
not necessarily causal association. " Dr. Christensen
responded that the issue is a big consideration for any
study that uses NHANES or other cross-sectional data.
When choosing chemicals for the analysis, compounds
were selected by considering whether animal or human
studies indicated associations between the broad
chemical class and liver function. A broad range of
exposures was considered. In addition, some compounds.
such as PCBs and dioxins, are persistent; body burden at
a given time is indicative of a person's exposure history
for years or decades. Biomonitoring urine concentrations
often represent short-term past exposures. All such
factors are a consideration when inferring associations.
especially when inferring causality. Another questioner
asked, "Do you have any genetic data to include in your
modeling? " The speaker responded that the NHANES
data include some measurements for single nucleotide
polymorphisms, but it is "restricted-use data," and
with limited time and resources, the data could not be
accessed for her analysis. She added that it "would be
another thing to consider!'
A questioner asked, "How can this be used to connect
with the health effects of the chemicals? " The speaker
responded that if the analysis can be considered in a
screening or hypothesis-generation context, a key CRA
step is problem formulation, planning and scoping. When
selecting health outcomes of concern based on exposure
scenarios of interest, the results of the comprehensive
analysis would be something to consider carefully.
using evidence from toxicology, epidemiology, medical
literature and other available evidence streams. A related
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question was asked: "Is there a way this method or
approach could be used for hypothesis generation, or is
it strictly applicable when you have data supporting a
relationship already, both in endpoint and chemical? "
Dr. Christensen replied that the method can be used not
only for screening and hypothesis generation but also
for examining the chemical weights and figuring out the
relative ranking of the hazard associations.
Another participant asked, "How can you assume or
be sure that the top quartile of some chemicals have
the same top quartile effects as the other chemicals? "
Dr. Christensen responded that an analysis will need
to consider the potency of different exposures. For
example, an extremely low-potency exposure can be in
the top quartile of exposure for a particular compound
with little effect on the outcome; conversely, a very
potent chemical in the second quartile might have a large
effect. She stated that she was uncertain if her analytical
approach addresses the question well and she will think
about it.
Webinar 5
December 19, 2012
Cumulative Levels and Effects—
Implementing a Unique Environmental
Justice Statute in Air Permitting in
Minnesota
Dr. Kristie Ellickson, Minnesota Pollution
Control Agency (MFCA)
The speaker, an MPCA risk assessor, incorporates CRA
in her work and is the lead on an EPA community-scale
air toxics grant targeting passive and active air sampling
for polycyclic aromatic hydrocarbons in an urban
environment. Her talk focused on three learning points.
described below.
1. Background on why the cumulative
levels and effects statute was enacted
and the specific statutory language
requiring analysis and consideration of
"cumulative levels and effects" as part
of air permitting decisions
The Minnesota statute (Minn. Stat. § 116.07, subd. 4a)
was passed in 2008 in response to local opposition
to a biomass incinerator proposed for siting in an
area surrounding the Phillips Communities in South
Minneapolis, the only area to which the law applies.
Under the law, before MPCA can issue permits in this
area, it first must "analyze and consider cumulative
levels and effects." The law does not use the terms
cumulative impacts or CRA. It includes all pollutants.
environmental media, sources, time periods and
receptors.
2. The methodology Minnesota developed
to screen, scope and consider the
available environmental health data and
information for the cumulative levels and
effects air permitting requirement
MPCA began its analysis by comparing air dispersion
modeling results against screening levels. MPCA used
federal and state standards or the National Ambient
Air Quality Standards (NAAQS) "significant impact
levels" for criteria pollutants. For air toxics, MPCA
used 10 percent of facility risk guidelines. The
facility's study area was defined as the farthest point
from a facility fence line at which the model showed a
pollutant exceeded the screening level. Pollutants above
screening levels also were used to determine which
health endpoints warranted further study, drawing on
EPA's Integrative Science Assessments for the criteria
pollutants and inhalation health benchmark technical
documents for air toxics. Minnesota's asthma, drinking
water, blood lead, U.S. Census and other data were
used. MPCA wrote a "how-to" process document for
conducting the cumulative analysis and a reference
document organized by "environmental health data and
context" for use by facility proposers in developing their
facility modeling, report and permit application.
MPCA received input into the proposed process first by
holding small technical "check-in" meetings of two to
five people, with results incorporated into the agency's
method. One of these meetings included neighborhood
leaders. Next, MPCA held a large open public meeting
that included a short presentation and an unexpectedly
lengthy question-and-answer period whose "huge range
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in scope" included questions about the ethics of staff
working in the area and MPCA's inclusion of synergistic
reactions between pollutants.
3. The results of two case studies of
cumulative levels and effects analyses
that were conducted, including
general background, communication
and outreach strategies, the permit
application processes and related
decision making
For the first permit processed by MPCA—for a light-rail
vehicles operation and maintenance facility—outreach
meetings were held, as is required for each permit and
each "cumulative levels and effects" analysis.
During the permit process, the applicant went through
several modeling iterations, which greatly refined the
facility's paint choices. The permit prohibits heavy
metals in paints, resulting in modeled cancer risks below
screening levels. Paints with diisocyanate also were
eliminated from the proposed list. With the eliminated
pollutants, MPCA achieved some "reduction in impacts."
The facility proposer's modeling, however, showed that
two pollutants were above screening levels: short-term
nitrogen dioxide (NO2), with emissions mostly from
space heaters, and 24-hour PM2 5, with emissions from
both space heaters and the paint booth. Environmental
health data for the health endpoints associated with NO2
(respiratory) and PM2 5 (cardiovascular) were pulled into
the cumulative levels and effects analysis. As much as
possible, the data were arranged and compared spatially.
Included in these data were socioeconomic indicators,
the National Air Toxics Assessment (NATA), MNRiskS
modeled results (the state's version of NATA), health
data, air measurements and potential nearby sources of
these or similar pollutants.
Overall, using MPCA's process, the resulting permit
limits were "significantly below what they would have
been." Developing trust was the most important risk-
communication step learned from the first permit. For
a second permit under way for a hospital's boilers and
emergency generators, the analysis led the proposer
to eliminate peaking programs for the facility's
generators. The method's biggest limitation is that.
although a variety of chemical and nonchemical
stressor information can be included, the final result
does not represent a true "integrated characterization."
Furthermore, if such indices could be created, "we
would have nothing to compare it to because we don't
have a cumulative health benchmark." Noting that the
statute "requires a much more comprehensive approach
to environmental regulation," Dr. Ellickson stated that
"even though the method isn't perfect, it's a good thing
that we're required to do that. We have done some
learning."
The speaker was asked, "Didyou make adjustments
to those screening levels for this methodology, or were
you just utilizing what you already had access to? "
Dr. Ellickson responded that MPCA adjusted the way
it calculates multi-pathway risks. Specifically, for
ingestion-based risks, the agency eliminated some of the
meat products people are assumed to eat and created an
"urban gardener" who eats some homegrown produce
and eggs produced in the backyard. Another questioner
asked about the response when data identified for further
analysis do not indicate health impacts. "How do you
overcome the trust issues for the community, which may
see that the health impacts do exist and [the] government
may be just not paying enough attention? " The speaker
answered that MPCA definitely has not overcome the
issue, with the comment received twice at one meeting:
"Withyou guys' giving this permit and allowing an
increase, you are negating our vulnerabilities." MPCA
strives to make clear that its analysis uses a fraction of
the state's facility risk guidelines, so the risks do not
exceed either state or federal standards.
A questioner asked, "Couldyou discuss what kind of
screening levels were used for air toxics? Was it one-
in-a-million cancer risk? " Dr. Ellickson stated that for
noncancer effects, MPCA sums all of the risks for a
facility's chemicals—both from ingestion and inhalation
exposures—and uses the facility risk guideline of 1.0
for hazard indices. If a pollutant-specific result is above
0.1 (10% of the facility risk guideline), then further
environmental health data related to the health effects of
that pollutant are included in the cumulative levels and
effects analysis. Similarly, for cancer, all of a facility's
chemicals are summed—also for both ingestion and
inhalation—and MPCA uses a one-in-100,000 for the
total facility risk guideline. However, if a pollutant-
specific cancer risk is above one-in-a-million, then
environmental health data related to the cancer health
endpoint are required to be included in the cumulative
levels and effects analysis. To repeat, the screening
levels for air toxics are 10 percent of the total facility
risk guidelines. Dr. Ellickson also was asked, "If some
community had existing health conditions of concern
[e.g., "socioeconomic status health issues"], how
are those factored into your permitting decisions? "
She replied that MPCA obtains all of the Health
Department's data: asthma outcomes, cardiovascular
events, blood lead and the like. In Hennepin County.
a survey was conducted asking, "What type of health
insurance do you have?" "Is there a smoker in the
house?" and similar questions. The information is
presented to decision makers as part of the final decision-
making process.
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Webinar 6
January 30, 2013
Integrating Susceptibility Into
Environmental Policy—
Implications and Information Needs
for Cumulative Risk Assessment
Dr. Ramya Chari, Associate Policy
Researcher, RAND Corporation
Dr. Thomas Burke, Associate Dean for
Public Health Practice and Training and
Professor, The Johns Hopkins Bloomberg
School of Public Health
Dr. Chari's expertise is in environmental health risk
assessment, environmental epidemiology and the
assessment of population exposure to environmental
pollutants, and Dr. Burke is Chair of the National
Academy of Sciences (NAS) Committee on Improving
Risk Analysis. Their talks focused on three learning
points, described below.
1. Strengths and limitations in the use of
epidemiological data for environmental
decision making in the context of
cumulative risks
Dr. Chari described a case study using EPA's process for
setting the 2008 NAAQS for lead. The study's goal was
to understand how susceptibility considerations—defined
as "characteristics of an individual or population that
alter biological response to environmental insults"—
may affect policy decisions. The study also aimed to
determine how an explicit, quantitative consideration
of susceptibility in policy development may change the
characterization of risk. For the NAAQS, EPA used an
"air-related IQ loss framework," which was a marked
difference from the original way the lead NAAQS was
developed because it was an effects-based rather than
an exposure-based approach. An equation multiplying
EPA's potential NAAQS level times the "air-to-blood
ratio" was used to arrive at an estimate of IQ loss known
as a concentration response (CR) function. The air-to-
blood ratio translates the allowable air concentrations
of lead into blood lead concentrations as a basis for
assessing IQ loss. Acceptable risk was defined as no
more than a 2-point IQ loss in the population mean IQ
for the subset of children exposed at the level of the air
quality standard.
The case study focused on SES as the susceptibility
factor of interest because SES is the most-studied
acquired (as opposed to intrinsic) factor, and the
literature suggests that the effects of lead may
vary across different SES levels. The researchers
systematically reviewed the epidemiological literature
to identify CR functions, focusing on 40 studies that
examined SES as a modifier of lead effects across
different SES groups. Only four of the 40 studies
provided enough information to extract CR functions for
low- and high-SES groups.
The speaker noted several caveats about the
epidemiological literature, which provides only
"suggestive evidence of an SES effect modifier of
lead neurotoxicity." There are "healthy debates" over
the four studies used in her analysis. For example, an
analysis of a Cincinnati, Ohio, cohort found significant
interactions between SES and lead only in earlier years.
indicating that differential effects may not persist or
may be attenuated in later years for unknown reasons.
Uncertainty in the analysis also was introduced by such
issues as the comparability of the four studies' measures
of exposure, outcome and SES status. Thus, the studies
did not provide definitive evidence about the existence or
magnitude of SES-lead interactions.
2. The importance of incorporating
susceptibility into CRA and data needs
Dr. Chari compared the results of her study with
EPA's results, using a figure based on the CR function
equation in which the x-axis represented different air
lead standards and the y-axis represented estimated
IQ loss. The figure showed EPA's standard of no more
than a 2-point IQ loss as a dotted line, and the Agency's
calculation that an air standard of 0.15 micrograms per
cubic meter (mg/m3) fulfilled the decision criterion.
Dr. Chari's study found, however, that under EPA's
0.15 mg/m3 standard, IQ loss for low-SES groups
exceeded the Agency's 2-point acceptable risk level.
Based on SES subgroup-specific CR functions, the
case study concluded that EPA must consider a stricter
standard of 0.1 mg/m3 to ensure that all SES groups
meet the Agency's acceptable risk level. By using CR
functions that do not account for the possibility of
increased susceptibility, "EPA's IQ loss framework may
not protect the target population to the desired extent."
The speaker noted that her study demonstrated a great
need for quantitative information on susceptibility for
the factor to be realistically included in EPA's policy
decision framework. Although there is not much debate
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about whether certain population groups might be
more susceptible, "the question in the debate really is
over how much more susceptible these populations
really are." To craft policies that are protective of all
populations, that information is necessary.
Dr. Chari added that the NAS committee chaired by
Dr. Burke recommended that EPA adopt a unified cancer
and noncancer dose-response approach in risk assess-
ment, a move that may result in more noncarcinogens
evaluated under a no-threshold model. As a result, in the
future EPA may rely less on "bright lines" indicating safe
exposure levels, with more deliberation over acceptable
risks. That development will make it more important
than ever to include susceptibility in policy decision
making. Determining acceptable risk depends on value
judgments and the population to which it is applied, and
quantifying susceptibility will foster open and transpar-
ent decisions about acceptability.
3. A new framework for risk assessment
and implications for cumulative risk
Dr. Burke presented the perspective on susceptibility and
CRA of the NAS Committee on Improving Risk Analy-
sis, which wrote the 2009 report Science and Decisions:
Advancing Risk Assessment. The committee emphasized
the importance of problem formulation in risk analysis
to ensure that the right questions are asked at the start of
an assessment. This is especially critical given the need
to consider susceptibility and population variability. To
achieve better environmental solutions, the committee
recommended a new three-phase approach: (1) problem
formulation and scoping; (2) planning and conduct of the
risk assessment; and (3) risk management. The unified
dose-response approach that Dr. Chari mentioned was
one of the report's most controversial recommendations.
Some people understood the recommendations to mean
that EPA would abandon reference doses and thresholds
in assessments. The recommendation, however, was
focused on the importance of understanding key aspects
of CRA: background disease processes and exposures.
possible vulnerable populations and modes of action that
may affect a chemical's dose-response in humans.
The speaker showed a chart that presented dose-response
curves for a susceptible subgroup, an average population
response and a non-susceptible (resistant) subgroup. The
susceptible subgroup's dose-response curve was depicted
as comparatively much steeper. The dose-response
relationship is dependent on environmental stressors.
heterogeneity in background exposure (endogenous
and xenobiotic) and biological susceptibility. A chart
showing an individual dose-response curve depicted
the large differences in the probability of adverse
health outcomes when background exposure and
susceptibility are included as factors. Dr. Burke then
showed a framework that the committee produced for
considering CRA and the factors that impact a disease
endpoint, such as "precursors for upstream indicators of
toxicity," modes of action and vulnerable populations.
A "vulnerable population assessment" would include an
understanding that low SES may increase vulnerability.
Factors considered under the framework should shape
how a conceptual model for dose-response selection is
developed. Dr. Burke also presented a stepwise approach
developed by Dr. Jonathan Levy. In step 1, a conceptual
model is developed for the stressors of interest that risk
management options may significantly influence. In
step 2, epidemiologic and toxicity data are evaluated
based on how the stressors can be incorporated into a
CRA targeted at stressors where closer analysis might
benefit risk management decisions most clearly. In step
3, the benefits of risk management options are evaluated.
and in step 4 the analysis is refined if the third step
does not have clear conclusions. Dr. Burke stated, "To
orient the [CRA] around risk management options is the
approach that we recommended so that we focus on the
stressors under consideration."
Dr. Chari was asked about the role of researchers, and
epidemiology researchers in particular, in addressing
the gap in susceptibility data. She responded that more
and better studies are needed, but efforts can be made to
organize, manage and report existing data "that would be
extremely helpful to getting policy makers access to the
type of data that would be directly relevant to crafting
programs and policies." Such efforts are crucial for
CRA, which requires extensive information.
A questioner asked, "Haw do you see advances in
toxicology around epigenetics informing cumulative risk
. . . such as understanding broader health endpoints or
system effects as opposed to specific health outcomes?"
Dr. Burke responded that this is an exciting time for
CRA because the current substance-by-substance
approach "is being changed to a health outcome, adverse
impact, systems approach'" that will be greatly supported
by high-throughput computational toxicology tests that
will enhance the understanding of mixtures and upstream
endpoints. New information about thresholds and
potential cumulative impacts will be available. A range
of data can inform CRA, "from those very fundamental
changes in indications of cellular and subcellular and
genetic impacts all the way to the evolution of health
impact assessment to better understand the community
health impacts of our environmental decisions" It will
have a huge impact on EPA's ability to rank, order and
make better decisions about the kinds of environmental
impacts the Agency seeks to prevent. Dr. Chari added
that as computational toxicology strengthens the ability
to assess genetic or "intrinsic" susceptibility, it would
be helpful for funding agencies to have a good model
of their exact research questions and goals across the
entire continuum of issues so that acquired susceptibility
factors are not neglected.
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Another questioner commented that Science and
Decisions seems oriented to CRA that begins with
identified stressors and asked, "Can it be applied to
[CRA] that is initiated by a real or perceived increase
in a disease rate?" Dr. Burke responded affirmatively.
As society moves beyond the 1970s' and early 1980s'
dominant concern with cancer prevention and takes
on "really difficult evolving health issues"—from
endocrine disruption through immunological impacts
and neurodevelopment—population health can provide a
starting point for the CRA conceptual framework. CRA
has a critical role to play in understanding the factors
contributing to baseline population risk. Dr. Burke also
responded to the question, "Are you recommending
considering nonchemical factors at the dose-response
assessments stage?" He stated that the NAS was
recommending that nonchemical factors that may
change the dose-response curve be considered during
development of a risk assessment's modeling approach.
The speakers were asked, "Even though we are now
exploring susceptibility, how do we get around the sort
of one-size-fits-all approach and account for differential
locational characteristics of cumulative exposures?"
Dr. Burke responded that the one-size-fits-all approach
to lead, for example, has been helpful, but if risk
assessment is going to adapt to evolving science—
whether at the molecular or population level—better
risk characterization using SES and other information is
needed. Dr. Chari added that CRA is related to "scenario-
based planning" and its output could be "something like
15 or 20 different risk scenarios." That flexible approach
does not require selection of only one critical health
endpoint, vulnerable population or exposure pathway.
"You can consider a range. You can rank scenarios.
You can try and get at worst-case and reasonable-case
scenarios in a way that's transparent and reasonable."
Dr. Burke made a point about ecological risk assessment.
noting that it is a problem-driven approach that
"really gets at the whole issue of what we are trying
to do here." CRA has much to learn from the overall
approach. Regarding any major data collection and
computational priorities, Dr. Chari suggested that
"studies that are constructed specifically to try and get at
issues of susceptibility" should be conducted. Dr. Burke
advocated for more exposure information and human
studies to understand the actual population impact. He
also suggested that better cumulative risk management
will require a "radical" iterative process in which risk
management decisions are evaluated later to determine if
they worked.
Webinar 7
ebruary
The Patterns of Pollution—Perspectives
From an Environmental Attorney and a
CIS Scientist on the Identification and
Assessment of Environmental Justice
Communities
David Deganian, Visiting Assistant Professor
of Law, Barry University School of Law
Nick DiLuzio, Project Manager/GIS Analyst,
NewFields
Mr. Deganian's work partly focuses on developing
laws to protect EJ communities, and Mr. DiLuzio
is a GIS analyst and project manager at NewFields.
an environmental and environmental sustainability
consulting firm. Their talks focused on three learning
points, as follow.
1. Methods for identifying and prioritizing
EJ communities using publicly available
data and GIS software
Mr. Deganian's Metro Atlanta Environmental
Project—a public interest project supported by a 2-year
fellowship from the University of Georgia School of
Law—required a methodology that would locate EJ
communities and then determine how they differed
from nearby communities, both in demographics and
types of pollution. The technical goals were to develop
an objective methodology for identifying and ranking
EJ communities; to evaluate the correlation between
community demographic characteristics (e.g., race.
language and income) and proximity to pollution points;
and to create a user-friendly EJ mapping system for
residents.
Mr. DiLuzio presented the methodology. He began by
defining the 14 counties that constitute metropolitan
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Atlanta as the study area. He then collected two types
of data: (1) eight publicly available pollution data sets.
which included information on permit violations, Toxics
Release Inventory reports, Superfund sites and facilities
holding permits to emit air pollutants or discharge water
pollutants, and (2) seven demographic data sets, such
as Census data, the American Community Survey data
set and data sets on mean housing value and median
family income. The project developed a model that
normalized these two collections of data sets based on
data type and spatial scale to enable an exact definition
of where the overlay exists between pollution sources
and demographic data. To address spatial scale, the
project created a grid in which every cell was 10 square
kilometers, to which was joined the pollution and
demographic data.
Mr. DiLuzio presented two maps that consolidated the
pollution data. One showed black points representing
air-emitting facilities; the study grid was overlaid on top
of the map and GIS software was used to sum up the
number of points within each 10 square kilometer cell.
The map summing up the black points was color-coded
using green and red to produce a second pollution map.
Green areas had zero facilities and red had between 11
and 25 facilities. The process was repeated for all eight
pollution data sets, producing eight color-coded areas
that were summed to produce a total pollution score map
with values ranging from 0 to 55.
To tackle demographic data, Mr. DiLuzio separated the
data into five categories—quintiles, each representing 20
percent of the distribution for the demographic variable.
He created a color-coded map showing on a census-tract
level the percentage of nonwhite population for the study
area; he created a second, similar map that rescaled and
reclassified the data based on the quintiles. In the rescaled
map, the number 1 represented communities that are
predominantly white (shades of blue) and 5 represented
communities that are predominantly nonwhite (shades of
pink). As with the pollution data, he repeated the quin-
tile exercise for all seven databases and summed them
to produce a total demographic score—ranging from a
minimum of 8 to a maximum of 35—that was presented
in a color-coded map he displayed. Areas scoring 8 (light
blue) were predominantly white, English-speaking, high
income, with high levels of high school graduation rates
and very low poverty; the top quintile areas (5), repre-
sented in pink, were primarily nonwhite and had low
income and high poverty.
The two mapping results were used to identify the 10
square kilometer blocks that were in the top quintile for
pollution (red) and for demographics (pink). These areas
were called EJ hotspots. Fifty-two blocks were identified
as hotspots, which then were ranked by their combined
pollution and demographic scores from 1 to 52.
2. Results of an environmental justice
assessment in the metropolitan Atlanta
region
Mr. Deganian discussed the results generated by the
methodology. The analysis showed that "there's a direct
relationship between the number of pollution points in a
block and the percentage of the population in the block
that's nonwhite." On average, blocks with less than 25
percent nonwhite populations had slightly fewer than
two pollution points, and blocks with more than 50
percent nonwhite populations had slightly more than
four pollution points. Pollution points are significantly
higher in areas where a large number of residents are
unable to speak fluent English; thus, EJ can be thought
of in terms of linguistic isolation. The study showed
a clear correlation between vacant housing rates and
pollution points. Housing values, however, were not
predictive of pollution points in the region; areas with
the highest housing values on average have slightly more
pollution points than where housing values are more than
$100,000 and almost three times more than where home
values are below $100,000. The speakers attributed this
to the fact that the region's population lives downtown
and in central Atlanta where housing values are higher
than in most areas of the region.
Besides identifying 52 EJ hotspots, the analysis identi-
fied what were called EJ "cold spots," defined as blocks
with relatively high pollution points but mostly white
populations and positive economic characteristics, such
as high housing values and income. Ten blocks were
identified as EJ cold spots. According to Mr. Deganian.
theoretically, "if all residents were impacted by pollution
equally, hotspots and cold spots would exist in the same
frequency," but that did not occur in the study. He com-
mented that the use of cold spots for comparison was a
useful way for communicating the point about EJ.
Mr. Deganian described the three worst hotspots. The
number-one EJ hotspot is located at the intersection
of three counties and is one of the southeast region's
largest warehousing and transportation centers. The
block's population is 86 percent nonwhite, and roughly
80 percent of residents are African American; vacant
housing rates are more than 20 percent. The second
hotspot is in the region's northeast, and the population
is largely white, with a high school graduation rate
below 65 percent. It has only one pollution point—the
City of Canton's water pollution control plant—but its
49 violations between 2008 and 2011 made the block a
top EJ hotspot. The third hotspot, in the central part of
the region, is called Buford Highway and is known as
having a diverse ethnic population of Asian and Hispanic
residents that is 45 percent linguistically isolated and has
a high school graduation rate below 70 percent. Lastly.
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Mr. Deganian noted that his project's EJ mapper allows
anyone to type in an address in the region to receive a
PDF report on the demographics and pollution in the
area. Eleven months after its release, the mapper had
1,600 hits.
3. Practical uses of this data from an
environmental attorney's perspective
A variety of uses have resulted from the analysis.
including the establishment of regular meetings among
EJ activists to identify and address a strategy for shared
goals. It also served as a public engagement vehicle.
giving Mr. Deganian a tool to make presentations to
various citizen audiences typically uninterested in
environmental issues. Fulton County, which has the most
EJ hotspots, passed an EJ resolution several months after
the project report was issued. The study also was a tool
for engaging with decision makers.
A questioner asked, "Shouldn t the pollution scores
that you developed be weighted by the degree of poten-
tial hazard?" Mr. Deganian responded that the project
participants discussed that idea but could not figure out
a way to provide weights that "wouldn 't be even more
subjective than giving them all a value of one." For
example, he said that he did not know how to give a risk
assessment value to a Toxics Release Inventory release
versus a Clean Water Act permit. Mr. DiLuzio added that
they approached the analysis not so much from a risk
perspective as from a "location perspective" to define
hotspots that might warrant further investigation. Anoth-
er questioner asked if the project had considered other
spatial grids besides 10 square kilometers. Mr. DiLuzio
stated that they had considered a 20-square-kilometer
grid but decided it was too large. A smaller grid of
5 square kilometers could be used if the analysts wanted
to focus on a single county or group of counties.
The speakers were asked if they had considered a metric
tool for analyzing the data set, because the graphs show
a trend but perhaps leave out a lot of high-impact qual-
itative results. "Perhaps that spatial regression anal-
ysis also would have been appropriate." Mr. DiLuzio
responded that such issues had been discussed but the
analysis had been constrained by time and the project
was only attempting a first-pass 40,000-foot view. A lot
of GIS and other statistical analyses could be performed
in the future. Mr. Deganian added that the project had
considered adding cancer statistics and other elements.
but that would have made it more difficult to achieve
the key goal of communicating to a variety of different
audiences. He agreed, however, that more complex or
thorough methods would be a useful addition to the
analysis. They also were asked if it would make sense to
specifically evaluate vulnerability when deciding which
types of issues to include in the analysis. Mr. Deganian
replied that it would be an interesting dimension to add
to the analysis because it would play into identifying EJ
hotspots, although his focus was on legal cases to ad-
vance policies. An objective way to evaluate vulnerabili-
ty would have to be developed.
A questioner asked, "Haw accurate are these existing
data sources, particularly the location of pollution
sites?" Mr. Deganian responded that critics noted that
some facilities counted in the study had been closed, but
he added that the data were those provided by the federal
and state government at the time of the study. Updating
the data would be an important step if enough people
were available to help. Another questioner commented.
"/ would think that some of your variables would be
correlated, such as percent nonwhite and linguistic
isolation. If so, then counting each of these would be
double counting this factor" Mr. DiLuzio responded
that much of the demographic information was drawn
from the variables used in similar previous studies.
Mr. Deganian added that the demographic characteristics
were tailored to the kinds of information of interest
to the study sponsors, such as linguistic isolation. He
agreed that some double counting likely did occur, but
"not as much as you would think in metro Atlanta," and
not such that it skewed the results.
Another questioner asked, "// is not apparent how you
used the number ofviolations in your study. They did not
affect your counts, correct?" Mr. Deganian stated that
they did affect the counts; each violation was included
as a pollution point if it was not a technical violation.
The study was more of a legal document than a risk
document. For a related question, he explained that the
violations data can generate other queries, such as, "Are
violations being enforced in higher income areas in a
different way than in lower income areas?" Mr. Deganian
also was asked how the analysis would be applied to the
location of a new permitted facility. He responded that
when a new facility is proposed for an EJ hotspot, attor-
neys can use the data to request a deeper review prior to
a new permit's receiving approval and to isolate areas
whose permitting decisions they would want to focus on
to ensure permitting is done properly.
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Webinar 8
March 20, 2013
A Semi-Quantitative Framework for
Cumulative Risk Assessment of
Waterborne Contaminants
Dr. Douglas Crawford-Brown, Director
of the Cambridge Centre for Climate
Change Mitigation Research, University of
Cambridge
The speaker has served on numerous committees and
panels, including the U.S. National Drinking Water
Advisory Committee, the U.S. Legislative Commission
on Global Climate Change and the European
Commission's Panel of Scientific Experts on Risk. His
talk focused on three learning points, described below.
1. Understanding competing philosophical
and policy foundations of cumulative risk
Dr. Crawford-Brown described two traditions of
conducting risk analysis: the individual rights tradition
in the United States and the cost-benefit analysis
utilitarian approach employed in the European Union
(EU). The goal in the United States is to achieve
reasonable certainty, for example, that drinking water
poses acceptable risk; it cannot be completely safe, but
everybody has that right and EPA's job is to produce
water that respects everybody's rights. The utilitarian
goal is to produce the most cost-effective enhancements
of overall welfare in a defined community.
2. Calculating cumulative risk based on
disability adjusted life years
The speaker stated that he would be discussing a
semi-quantitative framework—not a fully quantitative
one—that incorporates certain kinds of judgments. His
underlying message was that the EU's approach in the
regulatory sphere and the United States' approach are
slowly being harmonized, but a fundamental difference
nevertheless exists between the two. In the United
States, the regulatory framework centers on building
in uncertainty factors and modifying factors based on
points of departure. In the EU, the framework resorts
to Disability Adjusted Life Years (DALYs) and Quality
Adjusted Life Years (QALYs) and the like. In his view, it
is impossible to conduct a CRA under EPA's traditional
regulatory approach of using points of departure.
developing Reference Doses (RfDs) for chemicals with
uncertainty factors and so forth. His semi-quantitative
framework strips away the "policy apparatus" of
uncertainty factors, which can be restored after a CRA
is completed. To conduct a CRA, it is necessary to use
the utilitarian cost-benefit framework employing such
factors as DALYs and QALYs.
3. Using cumulative risk to identify
strategies of risk reduction for water
supplies
Dr. Crawford-Brown discussed his project using
the concept of the "risk cup." The semi-quantitative
framework analyzes how to choose between water
supplies of different purity by imagining glasses of
water in the cup and calculating the total risk from that
drinking water. Questions to pose are: Which glass meets
individual rights on all compounds? Which produces the
best overall welfare? Which does this at the lowest cost?
Cost matters because if the price of water rises as a result
of stricter standards and higher treatment costs, the poor
could face difficult financial choices, such as postponing
or neglecting health care visits or dropping access to
drinking water. Trade-offs can result in reduced overall
public welfare. Rates of asthma, high blood pressure
and other diseases are affected by the lack of health
insurance.
The speaker stated that the issue of cumulative risk is
most important in terms of EJ problems. He noted that
the risk management framework he was employing
within his CRA analysis was a classical multi-criteria
decision analysis methodology; the key to it is to define
which health effects "you actually care about in the
population" whose various risks are being assessed and
managed.
Commensurability is a key challenge in CRA. "What
are we going to do if we've got cancer that is being
produced by our risk cup, and we've got respiratory
diseases... reproductive diseases... liver damage and so
forth?" One view is to regard these various health effects
as incommensurable; the other is to reduce every health
impact to a common metric, which for economists is
the amount of dollars a person would be willing to pay
to avoid a health effect. The speaker's framework for
Commensurability is DALYs, QALYs or any other social
utility welfare function that can be compared when
examining the implications of the various glasses of
clean water in the risk cup.
-------
The speaker discussed approaches for "weighting"
effects, such as a O-to-10 semi-quantitative score based
on "care" (e.g., no discernible effect on quality of life.
mild discomfort, hospitalization, etc.). The DALY
calculation is semi-quantitative because weightings are
partly subjective. He then presented the eight steps in
his assessment framework, starting with the calculation
of a time-weighted lifetime average concentration of
each compound in water using monitoring data and
ending with the multiplication of the "mean individual
DALY" by the size of the exposed population to
obtain a "population cumulative risk" that is equal
to the "weighted total DALY value." The speaker
also presented slides showing the DALYs that were
calculated for 51 compounds in drinking water. The
results showed wide variations in the DALYs, and
only about five compounds contributed most of the
public health impact or DALYs, even though all of
the compounds analyzed were assumed to be at their
maximum allowable limit.
Dr. Crawford-Brown was asked how his work would
apply to the enormous effort at EPA to define more
appropriate assumptions about ingestion for children. He
responded that at the heart of the work he and colleagues
conducted was the need for a relatively simple way
to measure toxicity when dealing with hundreds or
thousands of compounds. They used EPA's IRIS RfDs.
but stripped out body weight assumptions and the like to
obtain an exposure level based on milligrams per liter. If
EPA is concerned about early life exposure, the Agency
will have to force the IRIS RfDs to reflect that sensitive
subpopulation.
Another questioner asked if the speaker had to deal
with criticisms that QALYs and DALYs are too close
to an economic valuation of life. Dr. Crawford-Brown
responded that he shares "legitimate concerns about
whether one can put a value on life." He stressed.
however, that QALYs and DALYs do not put an
economic value on life; they are a measure of how
important a particular effect is relative to others for a
person's quality of life, and they represent the "best of
the worst options'" available. An alternative would be to
avoid reducing effects to commensurable units and allow
decision makers to use their discretion, although the
result could produce an option that is not cost-effective.
with potentially significant public health implications.
A questioner sought clarification of Dr. Crawford-
Brown's statement that there is no difference between
cancer and noncancer risk. He responded that there is no
biological reason why cancer cannot occur on a threshold
model or noncancer effects must occur on a threshold
dose-response curve, as is currently assumed. He added.
"But if you believe that cancer is a probabilistic event,
and if you believe that noncancer effects are threshold
effects, then our methodology is not for you." Another
participant stated that EPA does not use the speaker's
interpretation of margin of safety. In reply, he stated
that when he was on EPA's Science Advisory Board, the
panelists frequently argued with EPA because they did
not agree with the Agency's interpretation of margin of
safety, which focuses on conversion and scaling issues
for an equal toxic dose, as opposed to formulating it as
"a decision problem with probability density functions
and so forth, with uncertainty and variability."
A final questioner stated that in economics "the costs
are not allocated across a population for environmental
justice concerns." The questioner asked, "Who bears
the costs in such a situation and who gets the benefits?"
Dr. Crawford-Brown acknowledged that the question
is philosophical, but he added that it is precisely at
"the heart of the kind of question EPA ought to be
asking" because cost-benefit analysis does not really
ask those questions. Furthermore, none of his CRA
analysis calculated economic impact. A DALY is not, he
emphasized, an economic measure; it is a public health
measure of impact.
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Webinar 9
April 17, 2013
Simulating Population Characteristics
and Exposures to Multiple Stressors for
a Community-Based Cumulative Risk
Assessment
Dr. Jonathan Levy, Professor and Associate
Chair of the Department of Environmental
Health, Boston University School of Public
Health
The speaker, an EPA Science To Achieve Results
(STAR) grantee, is interested in air pollution exposure
assessment, health risk assessment with an emphasis on
urban environments, multi-stressor exposure scenarios
and issues of heterogeneity and equity. His talk focused
on three learning points, described below.
1. The value of synthetic microdata for
community-based CRAs
Dr. Levy described a STAR-funded effects-based CRA
study focused on two health outcomes of interest:
Attention Deficit Hyperactivity Disorder (ADHD)-like
behavior and hypertension. The goal was to examine
the cumulative impacts of chemical and nonchemical
stressors on those two outcomes. His presentation
focused on the project's exposure assessment, which
involved constructing "synthetic microdata" and then
developing exposure models linking to those data. The
project used public microdata—individual records with
extensive data, but coarse geographic resolution—to
create models of simultaneous exposures to a large
number of stressors that were highly specific to
individuals in low-income New Bedford, Massachusetts.
The research was able to employ a very large, robust
data set from a cohort study that began in the early and
mid-1990s and is continuing today. Between 1993 and
1998, newborns from New Bedford and surrounding
communities were enrolled in the study, which examined
ADHD-like behavior and collected a host of exposure
data.
The speaker added that CRA exposure challenges have
been underappreciated, such as the need to model a large
number of stressors simultaneously. Because researchers
are interested in vulnerable subpopulations that might be
highly exposed to multiple contaminants, it is "important
to figure out not just the broad distribution of these
stressors but correlations among them, and individuals
or subpopulations who might be highly exposed to
two, three, four or five different stressors of interest."
To address the issue, exposure models must have high
resolution across demographics and space. Dr. Levy
noted that the project's fundamental premise was that
"if you have measurements of exposure—biomarker
measures or other measures on a subset of individuals
in a community—you can build regression models to
explain that variability and then apply those to the full
population."
2. Statistical methods by which synthetic
microdata can be generated and
validated, relying solely on public
databases
Analysts commonly collect a limited number of
exposure measurements and find a way to explain
variability, potentially allowing for extrapolation to
other populations. The approach could be used for
New Bedford if a lot of individual-level data were
available that included where people live and their basic
demographic attributes, but for privacy and other reasons
such data do not exist. The microdata on individual
attributes lack geographic resolution; Census data
generally only provide one or two variables at a time, but
never the full suite of cross-tabulated information. The
researchers combined these data to create a "synthetic
census" representing New Bedford's demographics
and geography. This approach has been employed
for decades by "micro-marketers" using geographic
and demographic data to target the marketing of their
products. It has not been used for health purposes, except
in a few recent papers looking at smoking, and it has
never been used for environmental health applications.
To construct "synthetic geographically resolved
microdata" for New Bedford in a way that could
inform the project's exposure models, Dr. Levy and
his colleagues used microdata from the U.S. Census
American Community Survey, which surveyed a random
sub-sample of 5 percent of the population, or about 9,000
people in New Bedford and surrounding communities.
A simulation approach (probabilistic reweighting using
simulated annealing) was used to determine the census
tracts where these individuals most likely lived, given
13 census tract-level constraints from the U.S. Census
American Community Survey—8 individual (e.g., sex.
age) and 5 household (e.g., household income, rent/own
status). The procedure was validated, showing that the
Census data and the constructed synthetic microdata
were a good fit, both for the constraints and for other
census fields.
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3. Approaches for predicting exposures to
key stressors as a function of synthetic
microdata, with an example of applying
this approach to cigarette smoking in a
low-income urban community
The results of the synthetic microdata simulations
were connected with an exposure model, and cigarette
smoking was the first proof-of-concept test, using the
Massachusetts Department of Public Health's 2006-2010
Behavioral Risk Factor Surveillance System data, part
of a large survey by the Centers for Disease Control and
Prevention. With more than 4,000 people identified as
residing in New Bedford, the researchers built a model to
predict the likelihood of smoking among the population
as a function of the demographic variables available
from the Census-based synthetic microdata. Although
the resulting map could not be directly validated, it was
possible to replicate the overall smoking rate in New
Bedford and previously reported demographic patterns.
By building a local model and linking it to the local
synthetic microdata, the researchers were able to capture
nuances of smoking in New Bedford that normally could
not be captured.
The researchers next built models for other stressors re-
lated to ADHD-like behavior with the goal of being able
to inform communities about measures that they could
take to reduce their exposures. The researchers built a
model with a multilevel structure that enabled them to
leverage their microdata to define geographic and demo-
graphic patterns. The model was designed to determine
some of the key behavioral predictors—such as fish con-
sumption, breastfeeding and smoking—that contribute
to PCB and other exposures of concern in New Bedford.
A map was generated showing the modeled distribution
of PCB exposures across Census tracts in New Bedford;
Dr. Levy strongly cautioned, however, that the exposure
model was not related to geography per se but to food
consumption patterns, demographics and other such
information. The researchers examined a nonchemical
stressor indicative of psychosocial stress, data from the
Home Observation for Measurement of the Environment
(HOME), which provides a proxy for parental stress. The
map based on HOME data was overlaid on other maps to
produce indications of communities—including subpop-
ulations—that might be at elevated risk across multiple
factors. Dr. Levy concluded that the model is "entirely
generalizable to other settings" besides New Bedford
as a framework for effects-based CRA modeling; the
analytical structure identifies high-risk populations and
focuses on risk-reduction strategies.
A participant asked Dr. Levy how the community
partners (who are required as part of a STAR grant)
reacted to the modeling approach for describing their
communities. He responded that the partners were
"intrigued" by the approach and pressed the researchers
to stay focused on building models that were relevant to
people's everyday lives and to risk reductions that they
could potentially implement. The partners advocated
for a community survey that was undertaken to obtain
current information. Another participant noted that the
four maps Dr. Levy presented in his slides showed very
different affected areas and asked if he is working on
developing joint stressor models. The speaker responded
that such models are the goal of the structural equation
modeling that he and his collaborators are working on.
Eventually, Dr. Levy envisions a single map or table that
''cuts across all stressors and gives a sense of the highest
risk subpopulation."
A participant asked, "Haw much is your model
extendable to other cities?" Dr. Levy responded that
he would be cautious in extending the model itself to
other cities because there are "a lot of local population
nuances that could mean certain behaviors, or certain
demographic variables, seem indicative of exposures,
and it just wouldn 't represent elsewhere." Nevertheless.
''the approach is extendable to other cities," and if
more exposure pathway variables were available "that
would enhance the generalizability." Another participant
asked what degree of certainty Dr. Levy's methodology
would bring if an analyst were looking for cause and
effect across multiple stressors. The speaker responded
that there are appreciable uncertainties and unexplained
variability in the modeling. He would provide a "fair
amount of caution before using it in something that was
approaching an epidemiologic investigation."
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Webinar 10
May 22, 2013
Why and How to Integrate Your
Assessment
Dr. Glenn Suter, Science Advisor, EPA
National Center for Environmental
Assessment, and Chair, Risk Assessment
Forum Oversight Committee
The speaker—who has a Ph.D. in Ecology and is
the principal author of three texts in the ecological
risk assessment field—has conducted research in the
development and application of methods for ecological
epidemiology and risk assessment. His talk focused on
three learning points, described below.
1. Why health and environmental
assessments need to be more integrated
Dr. Suter noted that "we all, human and nonhuman
alike," are exposed to the same environment and same
pollutants. Permitting, remedial and policy decisions
must "meet the needs of and protect humans, nonhuman
organisms, ecosystem processes and even economic
and political entities." Integration thus leads into the
domain of sustainability. Scientists must present a
coherent, consistent risk assessment across such issues
as multiple stressful agents or pollutants, multiple
endpoints, different levels of ecosystem organization
that affect organisms, populations, communities.
ecosystems and even global levels. Human, nonhuman
and socioeconomic systems face risks, and therefore
"integration is imperative" because without it risk
estimates will be incomplete, poor decisions will be
made and stakeholders will be confused by disjointed
assessments.
2. Ways in which assessments may be
integrated
The speaker described various ways that ecological risk
assessors deal with multiple agents and stressors—not
just toxic chemicals, but also temperature, suspended
sediment, physical habitat structure, nutrients, dissolved
oxygen and other aspects of the environment, which
also affect humans, although in different ways. As with
human health risk assessment, ecological risk assessors
begin by examining data on individual chemicals and
other stressors. They use exposure and effects additivity
models, and sometimes combined exposure and effects
additivity for heterogeneous mixtures of agents. To get
beyond the limitations of single-chemical testing and
modeling, however, ecological risk assessors developed
chemical mixtures toxicity testing. Test organisms—
most often fathead minnow and Ceriodaphnia dubia
(a species of water flea)—are exposed to a mixture
of chemicals that they experience in the environment
as a result of pollutants in effluent discharges. If the
tests show toxicity, assessors use toxicity identification
evaluation techniques to test and retest fractions of the
chemical mixtures to determine what is causing the
toxicity. Toxicity profiling is a new technique being
developed mainly in Europe for using tests to determine
causes of toxicity in mixtures.
Although mixtures toxicity testing is better than
single-chemical testing, the approach is limited by the
relatively small number of species tested, which may
not include sensitive species. The necessary life stages.
such as spawning adult fish, may not be included,
and the duration of exposure needed for chemicals
that bioaccumulate may be missing. To address those
limitations, biological surveys of animals or plants can
be conducted. For example, electrofishing involves
stunning the fish in a stream, weighing and measuring
them and examining them for gross pathology. It has
the advantage of including all species and life stages in
a real-world setting. The disadvantage is that it assesses
population- and community-level effects, which may
be less sensitive than organism-level effects seen in
a laboratory. Causation of field survey results can be
obscure, so EPA developed a stressor identification
method that is based on human health epidemiology for
determining causation in ecological systems. The method
was expanded into an expert system called CADDIS, the
Causal Analysis/Diagnosis Decision Information System.
Dr. Suter described three case studies involving
integrated assessments. In an assessment of the Poplar
Creek Embayment on Watts Bar Reservoir in Tennessee.
an ecological risk assessment based on conventional
toxicity tests, mixture toxicity tests and biological
surveys was conducted, along with a standard human
health risk assessment. Although the ecological tests
raised concerns about possible reproductive risks to
humans based on those found in mink, the human health
risk assessors rejected the data, causing public concern.
In the assessment of a mining waste site in the Coeur
d'Alene River Basin in Idaho, the National Research
Council criticized EPA for failing to do a good job of
integrating human health and ecological concerns to
protect all receptors from mining contamination. In the
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assessment for the proposed Pebble Mine in the Bristol
Bay watershed in Alaska, the Yupik villages asked
EPA to provide protection against the threats to salmon
fisheries, which are the main source of their food and
commercial livelihood, as well as a central part of their
spiritual culture.
3. How to decide on the type of integration
Dr. Suter described integrated human health and
ecological risk assessment frameworks. In 1998.
for example, the World Health Organization.
the Organization for Economic Cooperation and
Development, the European Union and the United
States developed an integrated human health and
ecological risk framework. EPA's Risk Assessment
Forum is completing a draft "Human Health Risk
Assessment Framework" that will create a better basis
for collaboration between human and ecological risk
assessors. Dr. Suter emphasized that integration does
not mean diverting ecologists to work on human health.
He concluded by stating that "risk assessment is in
everything" and various kinds of studies are necessary.
Environmental epidemiology is needed to determine
problematic conditions and their causes. Predictive
assessments other than risk assessments, such as cost-
benefit analyses, are needed. Outcome assessments are
required to determine whether decisions provide the
anticipated benefits. Integration should be conducted
in a way that better informs decisions and provides
a coherent understanding of the consequences of
alternative actions.
A participant asked Dr. Suter if any attempts have been
made to devise a common human health and ecological
risk metric. He responded that it has not been done and
would be a bad idea; important information is lost with
multi-metric indices. It is preferable to have multiple
endpoints that are presented in a coherent, integrated
manner. Another participant stated that because human
beings are assumed to be the most sensitive species, the
argument is made that human health risk assessments
would be protective of ecological receptors and no
ecological risk assessment is needed. Dr. Suter dismissed
the conclusion, saying that a fish put in tap water would
quickly die. He noted that "nonhuman organisms have
modes of exposure that cause them to be more exposed
than humans, like respiring water. They are more
intimately integrated into the environment than humans
are and some are inherently more sensitive!'
Asked about top research needs to advance integrated
assessments, Dr. Suter responded that from the
traditional lexicological standpoint, the ability is needed
to examine toxic effects in a common mechanistic
framework, such as adverse outcome pathways. Such
research would be helpful to both human health and
ecological risk assessors in developing models that
produce outputs "that are relevant to both those who
drink water and those who respire water." Another need
is for a better understanding of how humans interact
with the environment and benefit from having a high-
quality environment available to them. Studies show
that "people who have visual access to a park recover
from surgery faster than those who are looking out their
window at a wall!'
Dr. Suter responded positively to a question about
EPA assessors receiving more training in an integrated
perspective. EPA, however, lacks guidance or training
materials and faces inertia because many people are
invested in proceeding as they have always done. They
worry that if EPA adopted an integrated approach, the
Agency could be challenged for departing from practices
already approved by precedents. "There is inherent
institutional conservatism that we have to work against!'
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Webinar 11
June 26, 2013
A Novel Approach for Testing Interaction
Effects of Environmental and
Psychosocial Stressors on Disease Risk
in a Logistic Regression Model
Dr. Wenyaw Chan, Professor of Biostatistics
at the School of Public Health, University of
Texas, Health Science Center at Houston
Ms. Maria Jimenez, Research Coordinator
in the Division of Epidemiology, Human
Genetics and Environmental Sciences at the
University of Texas School of Public Health
Dr. Chan and Ms. Jimenez are involved in the STAR
program. Dr. Chan has more than 20 years working
in public health, and Ms. Jimenez has been a strong
advocate working on social justice issues for the past
47 years. Their talks focused on three learning points.
described below.
1. To describe the specific aims of
the project entitled "Hypertension
in Mexican-Americans: Assessing
Disparities in Air Pollutant Risks"
Dr. Chan described a 4-year project led by Dr. Elaine
Symanski with three collaborating institutions, including
community partners, which seeks to understand the
associations between air pollution and hypertension.
and psychosocial stress and hypertension. The project is
developing a new statistical method that will be applied
to evaluate the combined effects of environmental and
psychosocial Stressors on hypertension. It builds on the
"Mano a Mano Study" of more than 22,000 participants
of Mexican origin in Harris County, Texas, which
is under the direction of Dr. Sara Strom at the M.D.
Anderson Cancer Center.
Ms. Jimenez explained the community-based
participatory research component of the project.
involving three groups that interact with researchers:
(1) the existing Mano a Mano Community Advisory
Board composed of agency heads, nonprofit executives
and academicians who provide a broad view of Harris
County-area problems; (2) a Neighborhood Council of
Advisors (NCA) composed of 16 local residents with
an understanding of their residential areas convened by
the project to provide input and feedback; and (3) 27
cohort participants who live and work in the "Mano a
Mano corridor" neighborhoods and who participated in
four focus groups. Focus groups were held to learn about
important psychosocial Stressors as well as behaviors and
activities that influence exposure to air pollution.
Content analysis "domains" emerged from interchanges
between researchers and community members.
Four domains were identified: (1) stress related to
employment, economic, individual and family issues;
(2) pollution-related stress; (3) discrimination-related
stress; and (4) neighborhood-related stress. Using these
domains and other sources, researchers developed a
36-question pilot survey employing a frequency scale
with responses ranging from "not at all" to "most of
the time" for specific questions. Seven one-on-one
interviews have been completed, and 13 more are
planned. The speakers described plans to administer a
refined survey to more than 2,000 participants in the
fall of 2013 and to evaluate the interacting effects of
air pollution and stress on hypertension in the spring
of 2014, using traditional and new methods. (Note:
Interviews began in February 2014, with almost 900
interviews completed as this goes to press in July 2014.)
2. To explain the general, traditional
approach of evaluating the statistical
interaction of two factors on disease risk
Dr. Chan described the "interaction effect," or an
interdependent relationship between the effects of two
or more factors, in this case, between air pollution and
psychosocial stress. Traditional regression analysis
usually uses the product of two variables called a
"product term" as an interaction effect in a model; this
approach is problematic as there are other effects not
always represented in the form of the product term.
Because the traditional linear regression model contains
a high correlation between the product term and the
main effect term, this might create a so-called "multi-
collinearity problem" in the regression.
In addition, the interaction of the coefficient of the
interaction term is very difficult to interpret, "particularly
when we are talking about the main effects of continuous
variables."
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3. To discuss key elements of a new
approach for testing interaction effects
in a logistic regression framework and
to compare this new approach with the
traditional ones
As an alternative, the project researchers illustrated
their approach with a table in which each cell represents
different combinations of discretized factors X and
Z, and they used either a Monte Carlo integration
or a "bootstrapping analysis method" to calculate
probabilities of a disease. The analysis identifies for
which cells there is a high probability that interaction
exists between factors X and Z (e.g., air pollution and
psychosocial stress).
The advantages of the new method are that it can test for
overall interaction, rather than just testing for a particular
form of a product term. In addition, with the new method
there is no difficulty in interpreting the interaction
effect. Furthermore, with the product term used in
traditional regression analysis, an assumption is made
that interaction effects are constant across the values of
factors X and Z. The new approach does not make that
assumption because it focuses on the overall interaction
effect. Disadvantages of the new approach, however.
are that it is computationally very intensive—estimating
probabilities for each cell on the table requires 14 hours
of computer time—and it cannot estimate the magnitude
of the interaction effect because the method assumes that
the effect is not constant. (In the future, the magnitude of
the interaction effect for each cell can be estimated using
the proposed method).
Dr. Chan was asked if his methodology can discern
whether an interaction is additive, antagonistic or
synergistic. He responded that by rewriting the testing
hypothesis, it would be possible to differentiate the three
different scenarios. Another method that the project
researchers developed focuses on those interactions
and will be discussed in a forthcoming paper. Another
participant commented that the lack of an estimate for
the interaction effect magnitude is not an issue, but the
"effect magnitude" must be evaluated to determine if
the effect raises clinical public health concerns rather
than simply achieving statistical significance. Dr. Chan
responded that focusing on a clinical concern might
require more information to understand the interactions
of clinical stressors.
A participant asked Dr. Chan how he distinguishes
interactions that come from correlations among the
exposures from those that are about factors influencing
each other's biological impact. He stated that because the
project's methodology is testing for overall interaction
effect, we are not able to distinguish those differences.
To identify different sources of interaction effect might
require developing a new method, but meanwhile.
identifying where interaction occurs and does not occur
is useful. Responding to another question, Dr. Chan
agreed that theoretically his approach can accommodate
many different variables, but at a significant increase
in computer time required. Regarding the question of
how his methodology fits within EPA's risk assessment
paradigm, including cumulative risk, Dr. Chan
responded that the information provided through the
project's epidemiologic study—concerning interaction
effects between environmental and social stressors—
could be used in risk assessment because the method
allows researchers to identify subgroups for whom such
interaction effects are present.
Regarding communication of the results, Ms. Jimenez
noted that the NCA members recognize that they
have a responsibility to explain the project results
to neighborhood residents, which they will do at
several meetings after the results are made available.
Furthermore, several Houston-based experts in
educational methodologies are available for consultation
for communicating the results to the NCA who, in
turn, will communicate what they understand to other
neighborhood residents. A participant asked whether
the questionnaire items will collect information on an
individual's educational level and annual income, and
whether researchers will assess these factors that might
be associated with the level of air pollution, which is
typically higher in less desirable real estate locations.
and psychosocial stressors. She responded that she
believes some of that information is available and
Dr. Symanski confirms that data on educational level
are available but data on income are not.
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Webinar 12
July 24, 2013
CalEnviroScreen 1.0—A New Tool for
Evaluating California Communities
Dr. George Alexeeff, Director of the
California Environmental Protection Agency
(CalEPA) Office of Environmental Health
Hazard Assessment (OEHHA)
Mr. Walker Wieland, Environmental
Scientist, OEHHA, Sacramento
Dr. Alexeeff has served on three NAS panels and
serves on EPA Science Advisory Board committees;
Mr. Wieland's expertise includes geographic information
systems and watershed sciences. Their talk focused on
three learning points, described below.
1. Describe a science-based approach to
identify highly burdened ("environmental
justice") communities in California
CalEPA developed the CalEnviroScreen modeling tool
to broadly capture the relative burdens that California
communities face from environmental pollution, using
18 indicators of environmental and socioeconomic
conditions. It is not a health risk assessment process. The
tool is built around a definition whose key terms include
exposures, public health, environmental facts, emissions
and discharges, geographic area, pollution sources.
sensitive populations and socioeconomic factors. CalEPA
chose the geographic unit of ZIP codes because they are
a familiar scale, are not too small or too large and allow
a statewide comparison, among other reasons.
CalEnviroScreen's 18 indicators are divided into
two broad groups: pollution burden and population
characteristics. Within pollution burden, there are two
categories: exposures and environmental effects. Under
exposures, the model uses indicators of fine paniculate
matter (PM2 5) concentrations, ozone concentrations.
diesel PM emissions, pesticide use, toxic releases from
facilities, and traffic density. Under environmental
effects, the model includes cleanup sites, ground water
threats (leaking underground tanks and cleanups).
impaired water bodies, solid waste sites and facilities.
and hazardous waste facilities and generators. Population
characteristics encompass sensitive populations and
socioeconomic factors. Sensitive populations include
the prevalence of children and elderly, emergency
department visit rates and low birthweight rates.
Socioeconomic factors include educational attainment.
linguistic isolation, poverty—defined as the percent of
residents with household income below two times the
national poverty level—and race/ethnicity.
2. Describe how multiple stressors in
a community can be integrated with
vulnerability and exposure data
For each of the 18 indicators, the state's more than 1,700
ZIP codes are assigned a percentile value based on where
they fall in the distribution. For example, CalEPA had
a PM2 5 value for each ZIP code. Each ZIP code was
ranked from the highest to the lowest level of PM2 5 and
then the ZIP codes were divided up by percentiles from
0 to 100 percent. After scoring each of the codes.
CalEPA combined the 18 indicators. ZIP codes ranking
within the 90th to 100th percentile were given a score
of 10, those from the 80th to 90th percentile given a
score of 9, and so on down the line, with each ZIP code
receiving a score from 1 to 10 for each indicator. For
exposures and environmental effects, the maximum
score was 10, and those two scores were added together
as part of the methodology.
CalEPA also scaled population characteristics from
1 to 10. The distribution of poverty within the state, for
example, was classified by ZIP code, and then placed
within a distribution from the 90th to 100th percentile
to generate the values from 1 to 10. CalEPA then
multiplied the sum of the exposures and environmental
effects times the sum of the sensitive populations/
socioeconomic factors to produce a single score for the
individual ZIP codes. Scores were used to create color-
coded maps showing communities' relative cumulative
impact burdens. Higher scores were darker; lower scores
were lighter.
3. Understanding how to use the
CalEnviroScreen 1.0 tool
CalEnviroScreen 1.0, which is housed on the OEHHA
website, is available in English and Spanish and provides
various types of data files, as well as two color-coded
maps. One map shows only the highest scoring ZIP
codes in California, coded in blue for the top 5 percent
of ZIP codes, and in orange for the top 6-10 percent of
ZIP codes. The other map shows CalEnviroScreen scores
for all ZIP codes across the state color coded in shades
of blue. A user interested in Los Angeles communities
could zoom in on a particular ZIP code in that area. A
pop-up box provides the detailed basis of the scoring
behind that particular ZIP code, such as the ozone or
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PM2 5 percentile. Clicking an indicator brings up a
summary description of the data sources for the finding.
along with links to key reference documents.
Dr. Alexeeff was asked about the applicability of the
CalEnviro Screen tool in developing regulations or
environmental quality standards. He responded that it
is premature, except for providing more information
about communities potentially affected by pollution
or helping prioritize where regulatory action might be
needed. For setting standards, better understanding of
inter-individual variability is needed. Another participant
asked if Dr. Alexeeff anticipated that CalEPA will
integrate information about community vulnerability into
any risk assessments that might be conducted under its
existing programs. He replied that, although it is beyond
current capabilities, CalEPA is headed in that direction.
The situation is comparable to regulators' understanding
about children's health 12-15 years ago. Back then.
the information available was limited to the locations
of schools or large day care facilities. Today, there is
extensive knowledge about children's susceptibilities
that may increase their response to toxicants and age-
dependent sensitivity factors for carcinogenicity.
A participant asked Dr. Alexeeff how CalEnviroScreen's
drinking water quality indicator is addressing people
who obtain their drinking water from private wells.
He responded that CalEPA has yet to figure out that
issue and it is a major question for the agency. The
approximately 10,000 drinking water providers listed
by the California Water Resources Control Board must
serve at least 25 individuals to be listed in the database.
which provides some information about water quality.
It is unclear how that information will be incorporated.
For private wells, CalEPA lacks information about water
quality in the wells and ultimately might have to simply
indicate well locations. Asked how CalEPA quantifies
measures that are not risk-based, Dr. Alexeeff responded
that proximity to facilities or cleanup sites is a factor
that influences communities. In addition, sites were
characterized in terms of whether they were closed.
illegal, abandoned and on other factors used for scoring
the potential impact of the sites.
Another participant asked how pollution reduction will
affect linguistic isolation or how linguistic isolation
changes the potential effects of pollution. Dr. Alexeeff
noted that in early versions of CalEnviro Screen.
linguistic isolation was not included. A Bay Area
refinery, however, had a pollution release and the
system for telephoning residents to tell them to shelter-
in-place did not work for the segment of the Asian
community who did not speak English. Therefore, they
did not receive calls and were unaware of the refinery
release. That incident convinced CalEPA that the Asian
community was more vulnerable because they have less
information to protect themselves.
Dr. Alexeeff was asked how the tool's 18 indicators
relate to causes and effects, or "dials that managers can
control to reduce impacts in these various identified
communities." He explained that the tool does not
address causes and effects. Instead, some indicators
are considered indicators of population susceptibility.
Asthma incidence rates, for example, were used as an
indicator that individuals who have visited emergency
rooms for asthma are susceptible.
Webinar 13
Legal Authority for EPA to Use Cumulative
Risk Assessments in Environmental
Decision Making
Sarah Alves. ICF International
Ms. Alves, a manager at ICF International, has more
than 5 years of experience in the areas of regulatory
law, administrative process and public policy. She based
her talk on a paper entitled "U.S. EPA Authority to Use
Cumulative Risk Assessment in Environmental Decision
Making," which she co-wrote with Ms. Joan Tilghman, a
Senior Technical Specialist at ICF International. Her talk
focused on three learning points, described below.
1. Surviving a legal challenge to EPA
decision making based on a CRA
Surviving a legal challenge to EPA decision making
based on a CRA rests on (1) whether the Agency has
statutory authority to use this methodology; and
(2) whether the CRA methodology, analytical results and
Agency use of those results are "reasonable." Ms. Alves
described how a court would review a challenge to an
EPA CRA using a two-step process defined by the U.S.
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Supreme Court in a 1984 decision, Chevron vs. Natural
Resources Defense Council. First, using Chevron
Step 1, a court will independently review the relevant
statute to decide if Congress has directly spoken to the
precise issue in question. Next, in Chevron Step 2, if the
statutory language does not unambiguously resolve the
issue examined in Step 1, a court must defer to EPA's
interpretation of a statute that the Agency implements
provided that the interpretation is reasonable. In some
cases involving vague statutory language, Ms. Alves
said, "a court's analysis of reasonableness can involve
complex inquiries into the specific factual circumstances
of the decision, the placement of language in the relevant
statute and the legislative intent of Congress." Even
if a statute is ambiguous and a court finds that EPA's
interpretation of the law was reasonable, EPA must
demonstrate that its use of CRA in its decision-making
process was "rational and not arbitrary and capricious."
The speaker summarized her analysis by stating that the
legal viability of EPA's use of CRA to project risks from
cumulative effects will depend on the specific statuto-
ry authority under which the Agency is acting and the
soundness of the analysis it then yields. Courts can inval-
idate EPA decisions based on "bad science." Ms. Alves
noted that EPA's statutory authorities generally focus on
risks from single pollutants in a single exposure medium.
even if in reality exposures are to multiple chemical and
nonchemical stressors and despite the fact that EPA has
made Environmental Justice a priority. Two laws explic-
itly specify how EPA must consider cumulative effects.
but most impose more general provisions on the Agency
"to protect public health" and address greater than de
minimis risks. Overall, courts have accepted EPA's use of
risk assessment under different statutes as an analytical
tool in decision making.
2. Setting a formula for a legally sufficient
CRA-based decision-making process is
problematic
Setting a formula for a legally sufficient CRA-based
decision-making process is problematic because CRA
analysis necessarily involves uncertainty, and the
sufficiency of evidence of risks will differ depending
on the factual circumstances. Ms. Alves stated that a
stakeholder challenging an EPA decision can assert
that even if the Agency has the authority to use a CRA
methodology, there were flaws in the conduct of the
analysis itself or in the use of the results. The Supreme
Court has defined several reasons that a court must
vacate a federal agency's action, including (1) if the
agency has relied on factors that Congress had not
intended it to consider; (2) if the agency entirely failed
to consider an important aspect of the problem; (3) if the
agency offered an explanation for its decision that runs
counter to the evidence before it; or (4) if the decision is
so implausible that it cannot be ascribed to a difference
in view about the data or the product of agency expertise.
EPA risk assessments rely on a series of assumptions
that EPA believes reflect a reasonable understanding
of potential real-world conditions but which inherently
contain varying degrees of uncertainty. A court's analysis
of this kind of issue is often undertaken in Chevron
Step 2, when a court may tie a review of arbitrary and
capricious issues regarding EPA's factual decision record
to an inquiry into whether the Agency's interpretation of
its ambiguous statutory directive was reasonable.
In their article, Ms. Alves and Ms. Tilghman reviewed
a number of court cases and concluded that courts will
apply basic rules when evaluating whether EPA has been
arbitrary and capricious. "A court will find an agency to
be arbitrary and capricious if EPA fails to show a rational
relationship between its conclusions and the evidence
before it." Courts are likely to defer to EPA's expertise
and uphold the Agency's decision when a stakeholder
challenges the quality of the data or technical process
relied on by EPA or suggests that other data are more
persuasive. However, when the record under review
shows data gaps or missing steps in EPA's logic that
preclude a meaningful review by courts and other
interested stakeholders in the decision-making process.
challenges tend to succeed. When reviewing a challenge
to a risk assessment, courts attempt to ensure that EPA
performs the most rigorous analysis possible given the
available data and the inherent scientific judgment in
the selection of data and assumptions at various steps of
an assessment. If EPA fails to explain how its reliance
on the results of a CRA relates to its statutory directive
or how its decision is supported by the results, a court
would likely overturn that decision.
3. Case law suggests reasons a court would
uphold EPA discretion to use CRA-based
decision making
Case law suggests a court would uphold EPA discretion
to use CRA-based decision making if the court finds
from the record that (1) statutory authority contains a
broad, public health mandate; (2) data and assumptions
are rational, based on available information; and
(3) EPA's conclusions drawn from the CRA are
reasonable. Ms. Alves presented a table listing factors
that a court might consider when determining whether
EPA has authority to change its interpretation of a statute
that it implements. A court would approve of EPA's
reinterpretation (1) if the Agency provides a rationale
for the change; (2) if new evidence supports a different
interpretation to satisfy the statutory mandate; and
(3) if the Agency provides adequate notice and
opportunity for public comment on the methodological
changes. She noted that it is problematic to make a
broad statement regarding how to construct a CRA
analysis that would be upheld in a court of law because
a court's decision about the sufficiency of the evidence
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regarding risk will likely differ, depending on the data
available and the actual circumstances for any risk
analysis. A CRA can vary from a narrow consideration of
cumulative risks, such as assessing the combined impacts
of multiple contaminants to humans at a Superfund site.
to a broad CRA that includes nonchemical stressors.
Asked if a court could find that a qualitative CRA is
reasonable, but the quantitative method is unreasonable
or insufficiently accurate, the speaker responded that
if EPA's statutory mandate was vague or broad and the
Agency had some real evidence of cumulative effects
but simply could not quantify the effects perfectly, a
court would find that conclusion reasonable. Another
questioner asked if the burden is on EPA to show that
CRA would be allowable under a statute or if the Agency
would be shown deference. The speaker responded
that EPA has the burden of explaining why a statute
would allow use of a CRA and why it is reasonable to
do so, and it needs to explain that conclusion during
the decision-making process, not after the fact. To a
question about the legal foundation and arguments for
using CRA depending entirely on the strength of the
evidence, Ms. Alves said that EPA should not spend a lot
of resources on a CRA whose results the Agency knows
are going to be highly uncertain. A participant asked if
nonchemical factors affecting the potency of chemicals
of concern could be considered in a Superfund CRA.
The speaker responded that they could be considered.
but if the Superfund program wants to advance its
CRA methodology, it would have to change its internal
guidance and explain why it was doing so. Regarding
states and CRA, Ms. Alves said that they need clear EPA
guidance on its use; otherwise, they might be reluctant to
adopt a CRA approach in their decisions.
Webinar 14
November 20, 2013
Implementation of Cumulative and
Mixtures Risk Assessment in the Office
of Water—Past and Future
Dr. Elizabeth Doyle, Senior Scientist, Office
of Water (OW)
Dr. Doyle, a risk assessor with 28 years of experience
at EPA, including 14 years as a lexicologist and
exposure assessor in EPA's Office of Pesticide Programs.
addressed three learning points, described below.
1. An understanding of the current status
of mixtures in OW regulations
Dr. Doyle began by discussing the limited application of
mixtures assessment within OW under the Safe Drinking
Water Act (SDWA) and the Clean Water Act (CWA),
which require the use of cost-benefit analysis. Under the
SDWA, OW addresses two existing mixture groups. The
first group, radionuclides, includes two groups: gross
alpha emitters, and beta particle and photon emitters.
OW regulates both groups for a single health effect—
carcinogenicity—using one measurement technique, an
approach that Dr. Doyle explained was simple but has
been useful for the program since the mid-1970s. For
beta emitters, for example, an aggregate "maximum
contaminant level" (MCL) measure of 4 millirems
represents an aggregate measure of approximately 170
contaminants based on a "sum of fractions method." The
second group, disinfection byproducts (DBFs), contains
hundreds of chemicals that are regulated; haloacetic
acids and trihalomethanes are used as indicators that an
acceptable level of DBFs has not been exceeded.
2. The impact of statutory and regulatory
drivers in formulating new assessments
under the SDWA and CWA
At the behest of the National Research Council, former
EPA Administrator Lisa Jackson requested that OW
conduct more multichemical assessments as a means
of becoming more efficient and effective in how the
office regulated chemicals. In 2010, OW began working
on an implementable method of grouping chemicals
and concluded that such a method would require that
chemicals be linked by a common health effect as a
basis for grouping. In addition, OW concluded that the
grouped chemicals would have to be controllable using a
common process or treatment technique because it would
be too costly to deal with a random chemical mixture
that would require treatments to be changed multiple
times.
After evaluating several possible groups, starting
with 45 carcinogenic volatile organic compounds
(VOCs), OW selected the sample group of nitroso
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compounds to address first. These are DBFs all of
which are liver carcinogens that occur in response
to chloramination, a modification of the disinfection
process. Based on EPA's Guidelines for the Health
Risk Assessment of Chemical Mixtures, OW decided
the nitroso compounds would lend themselves to the
"relative potency factor approach," which requires the
identification of a common mode of action followed by
a calculation to express the toxicity of each compound
in the group as a proportion of the index chemical
N-Nitrosodimethylamine (NDMA). For example, a
chemical in the group, N-Nitroso-N-Diethylamine
(NDEA), might be calculated to be 1.2 times as potent
as NDMA, and the other chemicals in the group would
be calculated in a similar manner. OW has developed
the documentation for treating nitroso mixtures as a
group using the relative potency factor approach and
will issue that documentation in an upcoming regulatory
notification.
Returning to the VOCs, OW adopted a "response
addition approach" in which the carcinogenic risk
of individual compounds at a specific concentration
measured in drinking water is calculated and summed to
estimate the total VOC cancer risk for a water sample.
The approaches that OW used for nitroso compounds
and VOCs both require calculating a measured risk
value, rather than producing an MCL. OW refined
its VOC assessment by also examining dermal and
inhalation routes, going beyond the traditional focus on
oral exposure. In a number of cases, inhalation was the
most significant exposure route.
3. New ideas for future monitoring
strategies to improve the focus on
adverse outcomes
Looking to the future, Dr. Doyle stated that OW is
trying to further improve its effectiveness and efficiency
in implementing the SDWA and CWA. As the office
moves forward with CRAs, it has found that this process
is limited by the number of chemicals for which OW
has developed MCLs. For drinking water, OW has 73
chemicals with MCLs, implying zero risk for the other
chemicals for which there is no MCL. In addition, OW
cannot incorporate interactions among chemicals in
its assessments and faces uncertainties in its chemical-
specific calculations that propagate throughout the
assessments. To address these issues, OW has begun
examining "bioactivity measures" using the high- and
medium-throughput assays developed by the Office of
Research and Development (ORD), which will enable
the office to understand and remediate toxicity in both
drinking and surface water systems more directly.
OW sees a window of opportunity as states pursue pilot
projects on water reuse. California, for example, is
conducting a pilot project examining the potential for
using estrogenic activity related to endocrine disrupter
compounds as a first look at using bioactivity measures
to directly estimate a risk from chemicals in the water.
Although the approach is many years away from being
used, it holds the promise of being able to "measure
toxicity with a device." Bioassays also will be able to
estimate or measure interactions of contaminants. Such
bioassays have been used by OW in total maximum daily
load and concentrated animal feeding operation work.
Initially, bioactivity measures probably should be used
together with traditional MCLs. A fundamental need is to
understand what would constitute a "threshold," such as
a threshold for estrogenicity. Identifying which adverse
outcome pathways (AOPs) are the most important
will be key. A challenge will be to demonstrate the
relationship between AOPs and apical endpoints well
enough that the regulated community will accept the
association. Also, the tools will have to be usable by
treatment plants' trained operators in a cost-effective.
reproducible manner. Lastly, Dr. Doyle emphasized that
it will be critical to define remediation approaches when
concentrations of mixtures exceed acceptable levels.
The speaker was asked about OW's approach to VOC
cancer risks. She responded that the office is conducting
"total cancer summation" from the chemicals measured
in water, not summing MCLs. Regarding how the
new approach has affected the program's regulatory
approaches, Dr. Doyle responded that OW must work
within a cost-benefit framework to justify whether the
occurrence of VOCs is sufficient to justify the cost
of remediation. That is a significant limiting factor
that requires consideration. Another participant asked
whether too much uncertainty would hamper OW in
even attempting to address complex mixtures. She stated
that limiting its focus to the Contaminant Candidate
List and regulated chemicals caused problems because
OW was working with only a few hundred chemicals.
Requiring a grouping theme, such as a health effect, as
well as a treatment and a measurement approach for
mixtures, were limiting factors.
Responding to a question, Dr. Doyle stated that some
endpoints and methods—such as a zebra fish bioassay—
have been considered for monitoring the mixtures
process in the future, but at present, none have been
adopted. OW is in the early stages of an exploratory
effort. Asked about the application of epidemiological
studies to OW's work, she stated that the office could
draw on fairly large cross-sectional studies to identify
issues within populations, but Dr. Doyle was uncertain
if such studies would be applicable for cause-and-effect
assessments. On the process for public communications
about the effort, Dr. Doyle said that ORD's research plan
includes studies on applying bioactivity and bioassays
to municipal effluent, but no other activities are planned
because OW is not using AOPs in regulations.
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Webinar 15
December 11, 2013
Challenges in Making Risk Assessment
More Relevant for Risk Management—
A View From the European Union
Dr. Peter Calow, Research Professor,
University of Nebraska-Lincoln
Lawrence Martin, Science Coordinator,
EPA Risk Assessment Forum (RAF)
Dr. Calow's professional focus is on environmental
risk assessment, about which he has written more than
300 articles and 20 books; Mr. Martin is a biologist
who works in the Office of the Science Advisor where
his principal responsibilities center on managing the
RAF's CRA Technical Panel. Their talk focused on three
learning points, described below.
1. Relevance of environmental risk
assessments for risk management and
environmental policy
Dr. Calow underscored his view that the deployment
of risk assessment in risk management is "somewhat
disappointing" and that, consequently, one of the major
challenges is to make risk assessment more relevant
for risk management—that is, "more value-relevant" or
relevant to public preferences. This must be done in a
way that is transparent and avoids political interference
with the science. In his view, in Europe, and perhaps
in the United States, risk assessment faces two major
difficulties. First, the endpoints used often are far
removed from public preferences, measuring molecular
or cellular responses rather than lives, lifespan, quality
of life, human health or ecosystem services. Second, risk
characterizations often are expressed as thresholds—
hazard or risk quotients, margins of safety—that make
it impossible to "calibrate marginal changes in exposure
with marginal changes in effect" to produce optimum
management solutions, which require good dose-
response analyses.
2. Making risk assessments more
management relevant without
introducing bias
To compare different values—what the speaker described
as "chalk and cheese"—public preferences must be used
for weighting choices. For example, mercury risks from
energy-saving light bulbs involve trade-offs among
issues: human exposure from accidental breakage.
environmental risks from disposal, reduced emissions
from energy savings and climate impacts. The inclusion
of public preferences requires more dialogue between
risk assessors and risk managers. Ultimately, cost-benefit
analysis is needed to properly compare very different
preferences. The speaker advocated that all of the EU's
advisory committees should include both natural and
social scientists to facilitate the development of better
value-relevant risk assessments that also can be better
communicated to the outside world. Currently, neither
the EU nor the United States has the right kinds of
institutional arrangements to underpin the necessary
dialogue among risk assessors and other stakeholders.
3. Moving toward more value relevance can
facilitate CRAs
In his overview of progress being made in EPA's CRA
Guidelines, Mr. Martin noted that CRA can potentially
suffer a "kitchen sink crisis," in which the assessment
becomes too large, cumbersome and expensive. To
address that concern, from the outset a CRA requires
a clear statement from the risk manager regarding
the exact information needed to inform a specific
decision, as required for the first step in planning and
scoping a CRA. The 1996 National Research Council
report Understanding Risk describes the process as "a
mutual and recursive relationship between analysis
and deliberation" to avoid managers' improperly
imposing a preconceived analysis to reflect their policy
preferences, as occurred with "mad cow" disease in the
1990s. The analysis and deliberation process does not
involve efforts by risk managers to shape the outcome
of risk assessments to match their policy preferences
but instead seeks to ensure that, whatever their outcome.
assessments will adequately serve decision making.
Closely adhering to key concepts in EPA's Framework
for CRA, the evolving guidelines include a strong
emphasis on stakeholder involvement in population-
based assessments. The integration of nonchemical
stressors—including biological agents, physical stressors
and psychosocial stressors—in the CRA Guidelines goes
beyond the earlier understanding of such assessments.
The issues of how to address nonchemical stressors that
EPA has no authority to regulate and how to evaluate
vulnerability factors not specifically required under
statute are among the more difficult challenges the
Agency is working to resolve. Mr. Martin noted that
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CRA raises the complexity of effective communication
by an order of magnitude, including communication
at the very beginning, as well as at the end of the
assessment.
Dr. Calow was asked about the implementation of
recommendations made by an EU working group on
risk assessment and management. He responded that
implantation is still in its early stages, but he noted that
under the EU Registration, Evaluation, Authorization
and Restriction of Chemicals (REACH) legislation, two
committees were established: one on risk assessment and
the other on socioeconomic analysis. Both committees
are formally involved in decisions about chemicals.
Before the working group's recommendation on making
risk assessment more relevant to risk management
was issued, the two committees rarely exchanged
notes. Now they are beginning to do so, and the risk
assessment committee can take more account of what
the socioeconomic analysis committee really needs
to perform its tasks. He added that the exchange of
information is an encouraging sign of progress toward
overcoming the EU's reluctance to lower barriers
between risk assessment and management.
The speakers were asked about whether CRAs will be
used for health impact assessment and environmental
impact assessment. Mr. Martin responded that a CRA
is intended to inform a risk management decision; a
health impact assessment informs any number of related
decisions associated to whether to build a freeway.
site a building or plant many or no trees, which is not
necessarily a risk management decision. The two are
easily confused, but distinctions between them should be
made. With respect to the environment, EPA is striving
to incorporate the idea of human health and ecologically
integrated risk assessments.
Dr. Calow added that in his presentation, he discussed
integrated risk assessment, which differs slightly from
CRAs that focus on the impact of multiple stressors
on one target; integrated risk assessments focus on
the effects of one or multiple stressors on a number of
targets, some of which could be human health and some
of which could be environmental. In that situation where
analysts are trying to compare and weigh very different
things (chalk and cheese), public preferences are best for
weighing the different things. He stated that ecosystem
services, which Mr. Martin mentioned, are part and
parcel of the move toward value relevance because they
connect ecological change with the value-relevant issue
of how human health—lives, life spans and so forth—are
affected. He said: "You get them all down to common
units, and that seems to me to be the way to go if you are
dealing with complex cumulative and integrative risk
assessment situations."
Asked to elaborate on the idea of "common units,"
Dr. Calow commented that they are about quantifying
public preferences, which in turn boils down to quan-
tification in terms of monetary values. He stated that
monetary values are a "quantitative expression of public
preferences'" on such matters as Quality Adjusted Life
Years and other such measures. He noted, however, that
most people are very suspicious of monetization because
they do not really understand its basis, which is "all
about quantifying in a transparent way public preferenc-
es and getting them into the common units so we can do
these complicated risk assessments and the complicated
risk management that goes with it"
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ecordmgs
August 29, 2012. Ari S. Lewis. "Nonchemical
Stressors and Cumulative Risk Assessment: An
Overview of Current Issues and Initiatives."
http://www.epa.gov/ncer/cra/multimedia/webinars/2012/
aug2912-lewis.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2012/aug2912-questions.html
September 26, 2012. Neal Fann. "Characterizing
Cumulative Air Pollution Risks."
http://www.epa.gov/ncer/cra/multimedia/webinars/2012/
sept2612-fann.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2012/sept2612-questions.html
October 17, 2012. Dr. Jonathan London.
"Cumulative Environmental Vulnerability Analysis:
Opportunities for Innovation."
http://www.epa.gov/ncer/cra/multimedia/webinars/2012/
oct!712-london.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2012/octl712-questions.html
November 28, 2012. Dr. Krista Christensen.
"Assessing the Health Impact of Multiple
Environmental Chemicals."
http://www.epa.gov/ncer/cra/multimedia/webinars/2012/
nov2812-christensen.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2012/nov2812-questions.html
December 19, 2012. Dr. Kristie Ellickson.
"Cumulative Levels and Effects: Implementing
a Unique Environmental Justice Statue in Air
Permitting in Minnesota."
http://www.epa.gov/ncer/cra/multimedia/webinars/2012/
dec 1912-ellickson. html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2012/dec 1912-questions.html
January 30, 2013. Dr. Ramya Chari and Dr. Thomas
A. Burke. "Integrating Susceptibility Into Environ-
mental Policy: Implications and Information Needs
for Cumulative Risk Assessment."
http ://www. epa. gov/ncer/cra/multimedia/webinars/20137
jan3013-chari.html
http ://www. epa. gov/ncer/cra/multimedia/webinars/20137
j an3 013 -burke. html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2013/jan3013-questions.html
February 27, 2013. David Deganian and Nick
DiLuzio. "The Patterns of Pollution: Perspectives
From an Environmental Attorney and a GIS
Scientist on the Identification and Assessment of
Environmental Justice Communities."
http ://www. epa. gov/ncer/cra/multimedia/webinars/20137
feb2713 -speakers.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2013/feb2713 -questions.html
March 20, 2013. Dr. Douglas Crawford-Brown. "A
Semi-Quantitative Framework for Cumulative Risk
Assessment of Waterborne Contaminants."
http ://www. epa. gov/ncer/cra/multimedia/webinars/2013/
mar2013-crawford-brown.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2013/mar2013-questions.html
April 17, 2013. Dr. Jonathan Levy. "Simulating
Population Characteristics and Exposures to Multiple
Stressors for a Community-Based Cumulative Risk
Assessment."
http ://www. epa. gov/ncer/cra/multimedia/webinars/2013/
aprl713-levy.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2013/aprl713 -questions.html
-------
May 22, 2013. Dr. Glenn Suter. "Why and How to
Integrate Your Assessment."
http ://www. epa. gov/ncer/cra/multimedia/webinars/20137
may2213-suter.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2013/may2213-questions.html
June 26, 2013. Dr. Wenyaw Chan and Maria
Jimenez. "A Novel Approach for Testing Interaction
Effects of Environmental and Psychosocial Stressors
on Disease Risk in a Logistic Regression Model."
http ://www. epa. gov/ncer/cra/multimedia/webinars/2013/
june2613-speakers.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2013/june2613-questions.html
July 24, 2013. Dr. George Alexeeff.
"CalEnviroScreen 1.0: A New Tool for Evaluating
California Communities."
http ://www. epa. gov/ncer/cra/multimedia/webinars/2013/
july2413-alexeeff.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2013/july2413 -questions.html
September 25, 2013. Sarah Alves and Joan
Tilghman. "Legal Authority for EPA to Use
Cumulative Risk Assessments in Environmental
Decision-Making."
http ://www. epa. gov/ncer/cra/multimedia/webinars/2013/
sept2513 -speakers.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2013/sept2513 -questions.html
November 20, 2013. Dr. Elizabeth Doyle.
"Implementation of Cumulative and Mixtures Risk
Assessment in the Office of Water—Past and Future."
http://www.epa.gov/ncer/cra/multimedia/webinars/2013/
nov2013-doyle.html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2013/nov2013-questions.html
December 11, 2013. Lawrence Martin and Dr.
Peter Calow. "Challenges in Making Risk Assessment
More Relevant for Risk Management; A View From
the European Union."
http://www.epa.gov/ncer/cra/multimedia/webinars/2013/
dec 1113 -martin, html
http://www.epa.gov/ncer/cra/multimedia/webinars/2013/
dec 1113 -calow. html
Question-and-Answer portion:
http://www.epa.gov/ncer/cra/multimedia/
webinars/2013/dec 1113 -questions.html
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upplemental Materials
August 29, 2012. Ari S. Lewis. "Nonchemical
Stressors and Cumulative Risk Assessment: An
Overview of Current Issues and Initiatives."
Alexeeff, G., J. Faust, L. M. August, C. Milanes, K.
Randies, and L. Zeise. Cumulative Impacts: Building a
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http://oehha.ca.gov/ej/pdf/CIReportl23110.pdf
DeFur, P. L., G. W. Evans, E. A. Cohen HubaL
A. D. Kyle, R. A. Morello-Frosch, and D. R.
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Gee, G. C., and D. C. Payne-Sturges. 2004.
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"The Importance of Population Susceptibility for Air
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Overview of Methodological Approaches for Evaluating
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mdpi.com/1660-4601/9/2/370
Wesson, K., N. Farm, M. Morris, T. Fox,and B.
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October 17, 2012. Dr. Jonathan London.
"Cumulative Environmental Vulnerability Analysis:
Opportunities for Innovation."
Huang, G., and J. K. London. 2012. "Cumulative
Environmental Vulnerability and Environmental Justice
in California's San Joaquin Valley." International
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November 28, 2012. Dr. Krista Christensen.
"Assessing the Health Impact of Multiple
Environmental Chemicals."
Cave, M. S. Appana, M. Patel, K. C. Falkner, C.
J. McClain, and G. Brock. 2010. "Fob/chlorinated
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Gennings, C., R. Sabo, andE. Carney. 2010. "Identifying
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December 19, 2012. Dr. Kristie Ellickson.
"Cumulative Levels and Effects: Implementing
a Unique Environmental Justice Statue in Air
Permitting in Minnesota."
Ellickson, K.M., S. M. Sevcik, S. Burman, S. Pak, F.
Kohlasch, and G. C. Pratt. 2012. "Cumulative Risk
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January 30, 2013. Dr. Ramya Chari and Dr.
Thomas A. Burke. "Integrating Susceptibility Into
Environmental Policy: Implications and Information
Needs for Cumulative Risk Assessment."
Chari, R., T. A. Burke, R. H. White, and M. A. Fox.
2012. "Integrating Susceptibility Into Environmental
Policy: An Analysis of the National Ambient Air
Quality Standard for Lead." International Journal of
Environmental Research and Public Health 9 (4):
1077-96. http://www.mdpi.eom/1660-4601/9/4/1077
February 27, 2013. David Deganian and Nick
DiLuzio. "The Patterns of Pollution: Perspectives
From an Environmental Attorney and a GIS
Scientist on the Identification and Assessment of
Environmental Justice Communities."
Deganian, D., and J. Thompson. 2012. The Patterns of
Pollution: A Report on Demographics and Pollution in
Metro Atlanta. Atlanta: GreenLaw. http://greenlaw.org/
pdf/PatternsofPollutionFINALGreenLaw3-26-2012.pdf
March 20, 2013. Dr. Douglas Crawford-Brown. "A
Semi-Quantitative Framework for Cumulative Risk
Assessment of Waterborne Contaminants."
Crawford-Brown, D., and S. Crawford-Brown. 2011.
"The Precautionary Principle in Environmental
Regulations for Drinking Water." Environmental
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April 17, 2013. Dr. Jonathan Levy. "Simulating
Population Characteristics and Exposures to Multiple
Stressors for a Community-Based Cumulative Risk
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May 22, 2013: Dr. Glenn Suter. "Why and How to
Integrate Your Assessment."
Cormier, S. M., and G. W. Suter, 2d. 2008. "A
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July 24, 2013. Dr. George Alexeeff.
"CalEnviroScreen 1.0: A New Tool for Evaluating
California Communities."
Adams, L. S., and J. E. Denton. 2010. Cumulative
Impacts: Building a Scientific Foundation. Sacramento.
CA: Office of Environmental Health Hazard Assessment.
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Indicators. Sacramento, CA: Office of Environmental
Health Hazard Assessment, http://oehha.ca.gov/ej/
pdf/061213CalEnviroScreenSensitivity.pdf.
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and Screening Tool. Sacramento, CA: Office of
Environmental Health Hazard Assessment. http://oehha.
ca.gov/ej/pdf/042313CalEnviroScreenl.pdf.
September 25, 2013. Sarah Alves and Joan
Tilghman. "Legal Authority for EPA to Use
Cumulative Risk Assessments in Environmental
Decision-Making."
Alves, S., J. Tilghman, A. Rosenbaum and D. C. Payne-
Sturges. 2012. "U.S. EPAAuthority to Use Cumulative
Risk Assessments in Environmental Decision-Making."
International Journal of Environmental Research and
Public Health 9: 1-30. doi: 10.3390/ijerph90xOOOx.
December 11, 2013. Lawrence Martin and Dr. Peter
Calow. "Challenges in Making Risk Assessment More
Relevant for Risk Management; A View from the
European Union."
Calow, P., and V. E. Forbes. 2013. "Making the
Relationship between Risk Assessment and Risk
Management More Intimate." Environmental Science
and Technology 47: 8095-8096. dx.doi.org/10.1021/
es402705y.
The Scientific Committee on Consumer Safety, the
Scientific Committee on Health and Environmental
Risks, and the Scientific Committee on Emerging and
Newly Identified Health Risks. 2013. Making Risk
Assessment More Relevant for Risk Management.
Brussels, Belgium: The European Commission.
doi: 10.2772/34776.
-------
Appendix
Select Statutory Provisions Regarding
EPA Authority to Consider Risk
Statutory
Action
Consideration of Human Health
and Environmental Effects
Other Statutory Considerations On Risk
Assessment
;ieanAirAct(CAA)
Set National
Ambient
Air Quality
Standards
(NAAQS)
Set New
Source
Performance
Standards
(NSPS)
List Source
Categories of
Hazardous
Air Pollutants
(HAPs)
Set Initial
National
Emissions
Standards
for HAPs
(NESHAPs)
(aka Maximum
Achievable
Control
Technology
Standards)
Set Residual
Risk NESHAPs4
Must establish primary NAAQS "requisite to
protect the public health" while "allowing an
adequate margin of safety."1
42U.S.C. §7409(b)(1).
Must establish NSPS for a category of stationary
source when EPA determines that category
"causes, or contributes significantly to, air pollution
which may reasonably be anticipated to endanger
public health or welfare."
42U.S.C. §7411(b)(1)(A).
The CAA requires EPA to list categories of sources
of certain HAPs; these categories are further
divided into major sources and area sources.
Major sources are those sources that emit, or
have the potential to emit, any single HAP at a rate
of 10 tons per year or more, or 25 tons per year of
any combination of HAPs. 42 U.S.C.
§ 7412(a)(1). Fora "major source," EPA may
establish a cutoff emissions quantity of less than
10 or 25 tons per year "on the basis of the potency
of the air pollutant, persistence, [or] potential for
bioaccumulation..." 42 U.S.C. § 7412(a)(1).
EPA must list any category of area source (i.e., a
HAP source that is not a major source) "which the
Administrator finds presents a threat of adverse
effects to human health or the environment (by
such sources individually or in the aggregate) ..."
42 U.S.C. §§ 7412(a)(2), 7412(c)(3).
After listing the HAPs source categories, EPA
must establish NESHAPs for each category.
42 U.S.C. §7412(c)(2).
"With respect to pollutants for which a health
threshold has been established, the Administrator
may consider such threshold level, with an ample
margin of safety, when establishing [NESHAPs]."
42 U.S.C. §7412(d)(4).
Must promulgate residual risk NESHAPs "if
promulgation of such standards is required in
order to provide an ample margin of safety to
protect public health ... or to prevent, taking into
consideration costs, energy, safety, and other
relevant factors, an adverse environmental effect."
42 U.S.C. §7412(f)(2)(A).
For HAPs that are known, probable, or possible
human carcinogens, if the existing NESHAP
standard does not "reduce lifetime excess cancer
risks to the individual most exposed to emissions
from a source in the category or subcategory to
less than 1-in-1 million," EPA must promulgate
residual risk standards for the source category as
necessary "to provide an ample margin of safety to
protect the public health."5
42 U.S.C. §7412(f)(2)(A).
EPA may not consider
implementation costs.2
Must consider cost, and
any non-air quality health
and environmental impact
and energy requirements.
42 U.S.C. §7411(a)(1).3
For a "major source," EPA may
establish a cutoff emissions
quantity of less than 10 or 25
tons per year "on the basis
of ... characteristics of the air
pollutant, or other relevant
factors." 42 U.S.C. § 7412(a)(1).
Statute does not
mention risk.
Statute does not
mention risk.
Statute does not
mention risk.
Must consider cost, and
any non-air quality health
and environmental impact
and energy requirements.
42 U.S.C. §7412(d)(2).
Statute does not
mention risk.
Must consider costs, energy,
safety, and other relevant factors.
42 U.S.C. §7412(f)(2)(A).
Mentions risk.6
-------
Statutory
Action
Set Emission
Standards for
Mobile Sources
Set Mobile
Source-Related
Air Toxics
Standards8
Regulation of
Fuels
Consideration of Human Health
and Environmental Effects
Prescribe and revise motor vehicle emissions
standards for any class or classes of new motor
vehicles for any air pollutants that "cause, or
contribute to, air pollution which may reasonably
be anticipated to endanger public health or
welfare." 42 U.S.C. § 7521 (a)(1).
For heavy-duty trucks, the CAA states that based
on available information "concerning the effects
of air pollutants emitted from heavy-duty vehicles
or engines and from other mobile source related
pollutants on the public health and welfare," EPA
"may promulgate regulations ... applicable to
classes or categories of heavy-duty vehicles or
engines." 42 U.S.C. § 7521(a)(3)(B)(i).
Other Statutory Considerations On Risk
Assessment
Must prescribe and revise motor vehicle air toxics
emissions standards for air toxics that "cause, or
contribute to, air pollution which may reasonably
be anticipated to endanger public health or
welfare."9 42 U.S.C. § 7521 (a)(1).
The CAA authorizes EPA to "control or prohibit
the manufacture, introduction into commerce,
offering for sale, or sale" of a fuel or fuel additive
if any emission product of such fuel or fuel
additive "causes, or contributes, to air pollution or
water pollution (including any degradation in the
quality of groundwater) that may reasonably be
anticipated to endanger public health or welfare."11
42 U.S.C. §7545(c)(1).
Safe Drinking Water Act (SDWA)
Evaluate Must regulate contaminants that "may have an
Contaminant adverse effect on the health of persons," may
Candidate List13 occur in public water systems at a frequency and
level of public health concern, and where, "in the
sole judgment of the Administrator, regulation of
the contaminant presents a meaningful opportunity
for health risk reduction for persons served by
public water systems."14
42 U.S.C. §300g-1(b)(1)(A).
Set Maximum Must set MCLGs at a level where, in the
Contaminant Administrator's judgment, "no known or anticipated
Level Goals adverse effects on the health of persons occur
(MCLGs) and which allows an adequate margin of safety."
42 U.S.C. §300g-1(b)(4).
"Any [mobile source emission
standard] shall take effect after
such period as the Administrator
finds necessary to permit the
development and application of
the requisite technology, giving
appropriate consideration to the
cost of compliance within such
period." 42 U.S.C. § 7521 (a)(2).
For heavy-duty vehicle and
engine standards, EPA must
consider cost, energy, and safety
factors.
42 U.S.C. §7521 (a)(3)(A)(i).
"[N]o emission control device,
system, or element of design
shall be used in a new motor
vehicle or new motor vehicle
engine for purposes of complying
with requirements prescribed
under this subchapter if such
device, system, or element of
design will cause or contribute
to an unreasonable risk to
public health, welfare, or safety
in its operation or function."7
42 U.S.C. §7521 (a)(4)(A).
Must consider availability and
costs of the technology; noise,
energy, and safety factors; and
lead time."
42 U.S.C. §7521(l)(2).
Must consider other
technologically or economically
feasible means of achieving
emissions standards under
the CAA provisions governing
emissions controls on motor
vehicles.
42 U.S.C. § 7545(c)(2)(A).
EPA must consider a cost-
benefit comparison of emission
control devices that require
the proposed control or
prohibition with emission control
devices that do not require the
proposed control or prohibition.
42 U.S.C. § 7545(c)(2)(B).
Regulation of the contaminant
must present a meaningful
opportunity for health risk
reduction.
42 U.S.C. §300g-1(b)(1)(A).
None.
Mentions risk
(see column 2).
42 U.S.C.
§7521(a)(4).
Mentions risk.1
Mentions risk.12
Mentions risk
(see columns 2
and 3).
Risk assessment
required. See
42 U.S.C.
§300g-1(b)(3).
-------
Statutory
Action
Set National
Primary
Drinking Water
Regulations15
(NPDWRs)
Establish
Underground
Injection
Control (UIC)
Program
Requirements
Consideration of Human Health
and Environmental Effects
Must set the MCL for a contaminant as close to
the MCLG as is "feasible."16
Must perform risk assessments to establish
NPDWRs for contaminants,17 as well as analyze
likely health risk reduction benefits.18
Must set minimum requirements for state
programs to "prevent underground injection
which endangers drinking water sources."19
42U.S.C. §300h(b)(1).
Other Statutory Considerations On Risk
Assessment
Clean Water Act (CWA)
Set Technology-
Based
Standards21
Set Water
Quality
Standards23
(WQS)
Set Total
Maximum
Daily Loads25
(TMDLs)
Set Toxic
Effluent
Standards
Establish
Management
Practices and
Numerical
Limits for
Disposal
of Sewage
Sludge27
No requirement to look at health or environmental
effects.
Must set WQS to "protect the public health or
welfare ... taking into consideration their use and
value for public water supplies, propagation of fish
and wildlife, recreational purposes, and agricultural
industrial, and other purposes, and also taking into
consideration their use and value for navigation."24
33U.S.C. § 1313(c)(2)(A).
Must set TMDLs "at a level necessary to
implement the applicable [WQS] with seasonal
variations and a margin of safety which takes into
account any lack of knowledge concerning the
relationship between effluent limitations and water
quality." 33 U.S.C. § 1313(d)(1)(C).
Any toxic effluent standard must "be at the level
which the Administrator determines provides and
ample margin of safety."26 33 U.S.C. § 1317(a)(4).
Must set management practices and numerical
limits for sewage sludge containing toxic
pollutants that are "adequate to protect public
health and the environment from any reasonably
anticipated adverse effects of each pollutant."
33 U.S.C. § 1345(d)(2)(D).
Must "identify those toxic pollutants which, on
the basis of available information on their toxicity,
persistence, concentration, mobility, or potential
for exposure, may be present in sewage sludge
in concentrations which may adversely affect
public health or the environment, and propose
regulations specifying acceptable management
practices for sewage sludge containing each
such toxic pollutant and establishing numerical
limitations for each such pollutant for each use
identified." 33 U.S.C. § 1345(d)(2)(A)(i).
Must consider technological
feasibility, cost.
42 U.S.C. §300g-1(b)(4);
42 U.S.C. §§300g-1(b)(3)(C)(i)
(III)-(IV); 42 U.S.C.
§300g-1(b)(6)(A).
Congress did not address how
EPA should balance risks when
evaluating endangerment of
drinking water sources, and
instead gave EPA discretion
to give meaning to the
endangerment criteria.20
Must consider cost, technological
feasibility.22
None.
None.
The CWA requires each listed
toxic pollutant to be at least
"subject to effluent limitations
resulting from the application of
the [best available technology]
economically achievable for the
applicable category or class of
point sources..."
33 U.S.C. § 1317(a)(2).
Must promulgate regulations
that "specify factors to be taken
into account in determining
the measures and practices
applicable to each ... use or
disposal [of sewage sludge]
(including publication of
information on costs)."
33 U.S.C. § 1345(d)(1)(B).
Risk assessment
required. See
42 U.S.C.
§300g-1(b)(3).
Statute does not
mention risk.
Statute does not
mention risk.
Statute does not
mention risk.
Statute does not
mention risk.
Statute does not
mention risk.
Statute does not
mention risk.28
-------
Statutory
Action
Consideration of Human Health
and Environmental Effects
Other Statutory Considerations On Risk
Assessment
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and Federal Food, Drug, and Cosmetic Act |
as Amended by the Food Quality Protection Act (FQPA)
Pesticide
Registration2
Amend an
Existing
Registration30
Registration
Review31
Set Pesticide
Tolerances32
Must register a pesticide if the Agency determines,
among several criteria, that the pesticide "will
perform its intended function without unreasonable
adverse effects on the environment," and if the
pesticide, "when generally used in accordance
with widespread and commonly recognized
practice," will "not generally cause unreasonable
adverse effects on the environment."
7U.S.C. §§136a(c)(5)(C)-(D).
Must make a finding that the tolerance is "safe,"
meaning EPA has determined that there is a
"reasonable certainty that no harm will result from
aggregate exposure to the pesticide residue,
including all anticipated dietary exposures and
all other exposures for which there is reliable
information."33 21 U.S.C. §§ 346a(b)(2)(A)(i)-(ii).
In establishing, modifying, maintaining, or revoking
a pesticide tolerance or exemption, EPA must
assess the risk of the pesticide chemical residue
based on available information concerning the
likely exposure and susceptibility of infants and
children to the pesticide chemical residue and
must "ensure that there is a reasonable certainty
that no harm will result to infants and children
from the aggregate exposure to the pesticide..."34
21 U.S.C. § 346a(b)(2)(C).
FIFRA defines the term
"unreasonable adverse effects
on the environment" to mean:
"(1) any unreasonable risk to
man or the environment, taking
into account the economic,
social, and environmental costs
and benefits of the use of any
pesticide, or (2) a human dietary
risk from residues that result from
a use of a pesticide in or on any
food inconsistent with the [safety]
standard under [the FDCA]."
7 U.S.C. §136(bb).
If additional time is needed
to generate the required data
for an unconditional decision
on a new active ingredient,
EPA may grant conditional
registration. In such cases, EPA
must determine that use of the
pesticide is in the public interest.
7 U.S.C. §136a(c)(7)(C);
40CFR152.114.
Even if EPA cannot determine
that a pesticide tolerance is
"safe," the Agency still may
establish a tolerance if at least
one of the following conditions
exists:
(1) "Use of the pesticide chemical
that produces the residue
protects consumers from
adverse effects on health that
would pose a greater risk
than the dietary risk from the
residue."
(2) "Use of the pesticide
chemical that produces the
residue is necessary to avoid
a significant disruption in
domestic production of an
adequate, wholesome, and
economical food supply."
AND if both of the following
conditions are met:
(1) "The yearly risk associated
with the nonthreshold effect
from aggregate exposure to
the residue does not exceed
10 times the yearly risk that
would be allowed" for the
yearly risk to be considered
"safe."
(2) "The tolerance is limited so
as to ensure that the risk
over a lifetime associated
with the nonthreshold effect
from aggregate exposure
to the residue is not greater
than twice the lifetime risk
that would be allowed" for the
lifetime risk to be considered
"safe." 21 U.S.C.
§§ 346a(b)(2)(B)(i)-(iv).
Mentions risk
(see column 3).
7 U.S.C.
§136(bb).
Requires risk
assessment (see
columns 2 and
3).3521 U.S.C.
§§ 346a(b)(2)
(C)-(D).
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Consideration of Human Health
and Environmental Effects
Other Statutory Considerations On Risk
Assessment
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), aka Superfund
National
Contingency
Plan (NCR)36:
Assessment
and Listing of
Facilities
NCR: Remedy
Selection
Must establish "criteria for determining priorities
among releases or threatened releases throughout
the United States for the purpose of taking
[response] action" (i.e., criteria for listing which
facilities/locations with hazardous substance
releases need to be cleaned up).
Criteria and priorities must be based on "relative
risk or danger to public health or welfare or the
environment... taking into account to the extent
possible the population at risk , the hazard
potential of the hazardous substances at such
facilities, the potential for contamination of
drinking water supplies, the potential for direct
human contact, the potential for destruction of
sensitive ecosystems, the damage to natural
resources which may affect the human food
chain and which is associated with any release
or threatened release, the contamination or
potential contamination of the ambient air which
is associated with the release or threatened
release..."3742 U.S.C. § 9605(a)(8)(A).
Must "select a remedial action that is protective
of human health and the environment... and
that utilizes permanent solutions and alternative
treatment technologies or resource recovery
technologies to the maximum extent practicable.'
42 U.S.C. §9621(b).
EPA must "conduct an assessment of permanent
solutions and alternative treatment technologies
or resource recovery technologies that, in whole
or in part, will result in a permanent and significant
decrease in the toxicity, mobility, or volume of the
hazardous substance, pollutant, or contaminant."38
In assessing alternative remedial actions, at
a minimum, EPA must take into account: (1)
the long-term uncertainties associated with
land disposal; (2) the goals, objectives, and
requirements of the Solid Waste Disposal Act; (3)
the persistence, toxicity, mobility, and propensity to
bioaccumulate of hazardous substances and their
constituents; (4) short- and long-term potential for
adverse health effects; and (5) the potential threat
to human health and the environment associated
with excavation, transportation, and redisposal or
containment.
Criteria for listing facilities must
also "[take] into account... to
the extent possible ... State
preparedness to assume State
costs and responsibilities, and
other appropriate factors."
42 U.S.C. § 9605(a)(8)(A).
Mentions risk
(see column 2).
42 U.S.C.
§ 9605(a)(8)(A).
Must consider costs/
Mentions risk.40
EPA regulations
require risk
assessment.
See40CFR
300.430(a)(2),
300.430(d)(1).
-------
ndnotes
1 EPA must base NAAQS on relevant "air quality
criteria." 42 U.S.C. § 7409(b)(l). "Air quality criteria
for an air pollutant shall accurately reflect the latest
scientific knowledge useful in indicating the kind and
extent of all identifiable effects on public health or
welfare which may be expected from the presence
of such pollutant in the ambient air, in varying
quantities." 42 U.S.C. § 7408(a)(2). Criteria for an air
pollutant, "to the extent practicable, must include:
(1) variable factors (including atmospheric conditions)
which of themselves or in combination may alter a
pollutant's effects on public health and welfare;
(2) the types of air pollutants which, when present in
the atmosphere, may interact with such pollutants to
produce an adverse effect on public health or welfare;
and (3) any known or anticipated adverse effects on
welfare." 42 U.S.C. §§ 7408(a)(2)(A)-(C).
2 See Whitman v. American Trucking Ass'ns, 531 U.S.
457, 464-71 (2001) (holding that 42 U.S.C. § 7409(b)
"unambiguously bars cost considerations from the
NAAQS-setting process").
3 EPA has interpreted the provision requiring the
consideration of non-air quality impacts to mean
that the Agency must analyze the environmental
and energy impact of proposed emission control
requirements. However, a reasonable interpretation
of this directive could be that EPA may consider
whether a proposed regulation that decreases air
pollutant emissions might also increase some other
health or environmental risks (for example, create
water pollution). See Cass R. Sunstein, "Cost-Benefit
Default Principles," 99 Michigan Law Review 1651.
1664-65 (2001).
4 To address residual risks, the CAA provides for a
second regulatory phase of the HAPs program, which
focuses on reducing any remaining ("residual") risk
to the public health remaining from sources regulated
under the NESHAPs program.
5 Note that this statutory directive obligates EPA to
promulgate standards that provide an adequate margin
of safety, but does not require that EPA establish
residual risk standards that reduce the risk to below
10-6. See NRDCv. EPA, 529 F.3d 1077, 1081-1083
(D.C. Cir. 2008).
6 42 U.S.C. §§ 7412(f)(l)-(2). Although the statute
does not direct EPA to perform a risk assessment.
a risk assessment is arguably necessary for
carcinogenic HAPs for which the statute directs EPA
to promulgate residual risks standards "to provide
an ample margin of safety to protect the public
health" if the existing NESHAP standard does not
"reduce lifetime excess cancer risks to the individual
most exposed to emissions from a source in the
category or subcategory to less than 1-in-l million."
42 U.S.C. § 7412(f)(2)(A).
7 "In determining whether an unreasonable risk exists
... the Administrator shall consider, among other
factors, (i) whether and to what extent the use of any
device, system, or element of design causes, increases.
reduces, or eliminates emissions of any unregulated
pollutants; (ii) available methods for reducing or
eliminating any risk to public health, welfare, or safety
which may be associated with the use of such device,
system, or element of design, and (iii) the availability
of other devices, systems, or elements of design which
may be used to conform to requirements prescribed
under this subchapter without causing or contributing
to such unreasonable risk." 42 U.S.C. § 7521(a)(4)(B).
8 Mobile source air toxics are compounds emitted from
highway vehicles and non-road equipment that are
known or suspected to cause cancer or other serious
health and environmental effects. The 1990 CAA
Amendments require EPA to regulate air toxics from
motor vehicles by promulgating standards for fuels.
vehicles, or both. EPA's Office of Transportation and
Air Quality refers to these pollutants as "air toxics," as
opposed to HAPs. This table follows that convention.
although many mobile source air toxics are also HAPs
regulated under the NESHAP program for stationary
sources.
9 Note that EPA must establish mobile source air toxics
emission standards under the same criteria as regular
mobile source emissions standards.
10 "Not later than 18 months after November 15, 1990,
the Administrator shall complete a study of the need
for, and feasibility of, controlling emissions of toxic
air pollutants which are unregulated under this chapter
and associated with motor vehicles and motor vehicle
fuels, and the need for, and feasibility of, controlling
such emissions and the means and measures for such
controls. The study shall focus on those categories
of emissions that pose the greatest risk to human
health or about which significant uncertainties remain.
including emissions of benzene, formaldehyde, and
1,3 butadiene." 42 U.S.C. § 7521(1)(1).
11 EPA may regulate a fuel under the CAA only if the
Administrator "finds, and publishes such finding, that
in his judgment such prohibition will not cause the use
-------
of any other fuel or fuel additive which will produce
emissions which will endanger the public health or
welfare to the same or greater degree than the use of
the fuel or fuel additive proposed to be prohibited."
42 U.S.C. § 7545(c)(2)(C).
12 "The gasoline shall have no heavy metals, including
lead or manganese. The Administrator may waive the
prohibition contained in this subparagraph for a heavy
metal (other than lead) if the Administrator determines
that addition of the heavy metal to the gasoline
will not increase, on an aggregate mass or cancer-
risk basis, toxic air pollutant emissions from motor
vehicles." 42 U.S.C. § 7545(k)(2)(C).
13 The SDWA requires EPA to publish a list of currently
unregulated contaminants that may pose risks for
drinking water (referred to as the Contaminant
Candidate List, or CCL) every 5 years and to make
determinations on whether to regulate at least five
contaminants from the CCL with a National Primary
Drinking Water Regulation (NPDWR) every 5 years.
See 42 U.S.C. § 300g-l(b)(l)(B).
14 "Such findings shall be based on the best available
public health information..."42 U.S.C.
§ 300g-l(b)(l)(B)(ii)(II).
15 NPDWRs must include either maximum contaminant
levels (MCLs) or treatment technique requirements
that reduce the level of the contaminant so
that it satisfies the requirements of the SDWA.
42 U.S.C. § 300f(l)(C) (defining "primary drinking
water regulation" to mean a regulation that specifies
for each contaminant either an MCL or, if it is not
economically or technologically feasible to ascertain
the level of the contaminant, treatment techniques that
lead to a reduction in the contaminant level sufficient
to satisfy section 1412).
16 EPA may "establish a [MCL] for a contaminant at a
level other than the feasible level, if the technology.
treatment techniques, and other means used to
determine the feasible level would result in an
increase in the health risk from drinking water by
(i) increasing the concentration of other contaminants
in the drinking water, or (ii) interfering with the
efficacy of drinking water treatment techniques ...
that are used to comply with other [NPDWRs]." If
using this authority, EPA must set the MCL or require
alternative treatment techniques to "minimize the
overall risk of adverse health effects by balancing
the risk from the contaminant and the risk from other
contaminants" that would be affected by the feasible
level. 42 U.S.C. § 300g-l(b)(5).
17 In a provision titled "Risk assessment, management.
and communication," the SDWA directs EPA to
use "the best available, peer-reviewed science and
supporting studies conducted in accordance with
sound and objective scientific practices" when
setting standards under the SDWA. This section
further directs EPA to produce a public health effects
document in support of any NPDWR, specifying
"each population addressed by any estimate of public
health effects," "the expected risk or central estimate
of risk for the specific populations," "each significant
uncertainty identified in the process of public health
effects and studies that would assist in resolving the
uncertainty," and peer-reviewed studies "that support.
are directly relevant to, or fail to support any estimate
of public health effects and the methodology used
to reconcile inconsistencies in the scientific data."
42 U.S.C. § 300g-l(b)(3)(A)(i)-(v).
18 In a provision entitled "Health risk reduction and cost
analysis," the SDWA requires EPA, when proposing
a NPDWR that includes an MCL, to publish, seek
comment on, and use an analysis of the quantifiable
and non-quantifiable health risk reduction benefits
that are likely to occur as the result of treatment to
comply with each MCL being considered, as well as
the risk reduction benefits "that are likely to occur
from reductions in co-occurring contaminants that
may be attributed solely to compliance with the
[MCL], excluding benefits resulting from compliance
with other proposed or promulgated regulations."
42 U.S.C. §§ 300g-l(b)(3)(C)(i)(I)-(II).
19 Underground injection endangers drinking water if
it "may result in the presence in underground water
which supplies or can be reasonably be expected to
supply any public water system of any contaminant.
and if the presence of such contaminant may result in
such system's not complying with any [NPDWR] or
may otherwise adversely affect the health of persons."
42 U.S.C. §300h(d)(2).
20 See Miami-Bade County v. EPA, 529 F.3d 1049, 1063
(llth Cir. 2008) ("Through repeated reference to
the possibility that [an underground drinking water
source] could be endangered, Congress established
no particular metric for evaluating endangerment.
Instead, it explicitly left the EPA to give specific
meaning to the endangerment standard.").
21 EPA must establish effluent limitations guidelines
and standards for different non-municipal (i.e..
industrial) categories, which are developed based
on the degree of pollutant reduction attainable by an
industrial category through the application of pollutant
control technologies. See http://cfpub.epa.gov/npdes/
techbasedpermitting/effguide.cfm (last accessed Feb
13,2012).
22 See 33 U.S.C. § 1314(b) (describing "best practicable
control technology," "best available technology," and
"best conventional pollutant control technology");
http://cfpub.epa.gov/npdes/glossary.cfm?program_
id=0 (last accessed Feb. 13, 2012).
-------
23 The CWA directs states to adopt WQS for their
navigable waters. 33 U.S.C. § 1313(c). Any new or
revised WQS must be submitted to EPA for review
and approval. 33 U.S.C. § 1313(c)(2)(A). If EPA
determines that any revised or new state standard is
not consistent with applicable CWA requirements, the
Agency must inform the state and specify the changes
to meet such requirements. 33 U.S.C. § 1313(c)
(3). If the state does not adopt such changes within
90 days, EPA must promulgate the standards.
33 U.S.C. §§ 1313(c)(3)-(4).
24 The CWA directs EPA to publish recommendations
periodically for states to use in setting water quality
criteria to protect recreational and aquatic life uses of
waters. EPA's water quality criteria must accurately
reflect the latest scientific knowledge "on the kind and
extent of all identifiable effects on health and welfare
including, but not limited to, plankton, fish, shellfish.
wildlife, plant life, shorelines, beaches, esthetics, and
recreation which may be expected from the presence
of pollutants in any body of water, including ground
water." 33 U.S.C. § 1314(a)(l)(A).
25 For waters in which technology-based standards have
proven insufficient to meet the WQS, states must
establish a "total maximum daily load" (TMDL) for
each regulated pollutant. Essentially, a TMDL is a
calculation of the maximum amount of a pollutant that
a water body can receive and still safely meet WQS.
See http://water.epa.gov/lawsregs/lawsguidance/
cwa/tmdl/ (last accessed Feb. 13, 2012). States must
submit TMDLs to EPA for approval, and if the Agency
does not approve, EPA is authorized to promulgate
TMDLs it considers necessary to meet the WQS.
33 U.S.C. § 1313(d)(2).
26 A toxic effluent standard must "take into account the
toxicity of the pollutant, its persistence, degradability.
the usual or potential presence of the affected
organisms in any waters, the importance of the
affected organisms and the nature and extent of the
effect of the toxic pollutant on such organisms, and the
extent to which effective control is being or may be
achieved under other regulatory authority."
33 U.S.C. §1317(a)(2).
27 Where use or disposal of sewage sludge (biosolids)
resulting from municipal waste treatment "would
result in any pollutant from such sewage sludge
entering the navigable waters," such disposal is
subject to the standards and permit requirements of the
CWA. 33 U.S.C. § 1345(a)-(b).
28 Although the statute does not use the word "risk," a
Federal appellate court has interpreted EPA's sewage
sludge statutory authority to set standards to protect
"from any reasonably anticipated adverse effects" as
mandating regulations that bear some relation to risk.
See Leather Industries of America, Inc. v. EPA,
40 F.3d 392, 400 (D.C. Cir. 1994) (remanding sewage
sludge effluent limitations to EPA because they were
based on the 99th percentile concentrations in current
sludge output, rather than based on risk)
29 FDCA and FIFRA do not direct EPA to regulate
pesticides using standards, but instead require EPA
to evaluate pesticides and their tolerances case-by-
case and periodically through the registration and
registration review processes.
30 If a registrant has a product previously registered with
EPA and wishes to make a change to the registration
(e.g., changing the product formulation or adding a
new use), the registrant must file an application to
amend its registered product, and EPA must approve
the amendment under the FIFRA registration criteria
before the registrant may legally distribute or sell the
modified product. 40 CFR 152.44(a).
31 The FQPA requires that EPA review pesticide
registrations at least once every 15 years.
7 U.S.C. § 136a(g)(l)(A). The statute states only that
the "registrations of pesticides are to be periodically
reviewed," without specifying the criteria by which
EPA is to review the registrations. EPA has interpreted
its registration review authority as requiring the
Agency to make "a determination that a pesticide
continues to meet the standard[s] for registration
in FIFRA," i.e., that a pesticide will not pose an
unreasonable risk to man or the environment. See
Final Rule, Pesticides, Procedural Regulations for
Registration Review, 71 FR 45720, 45725 (Aug. 9,
2006); 40 CFR 155.40(a)(l).
32 As amended by the FQPA, the FDCA authorizes EPA
to set tolerances, or maximum residue limits, for
pesticide residues on foods. 21 U.S.C. § 346a(b)(l)
(authorizing EPA, either in response to a petition or
on the Agency's own initiative, to issue regulations
"establishing, modifying, or revoking a tolerance for a
pesticide chemical residue in or on a food").
33 The statute establishes nine specific factors "among
other relevant factors" that EPA must consider in
establishing, modifying, maintaining, or revoking a
pesticide tolerance or exemption, including several
factors relating to the health effects of the pesticides
and the relation of those studies to human health risk.
See 21 U.S.C. § 346a(b)(2)(D).
34 EPA must use "an additional tenfold margin of safety
... to take into account potential pre- and post-natal
toxicity and completeness of the data with respect
to exposure and toxicity to infants and children."
21 U.S.C. § 346a(b)(2)(C). EPA may "use a different
margin of safety for the pesticide chemical residue
only if, on the basis of reliable data, such margin will
be safe for infants and children."
35 The legislative history of the FQPA, which established
the "reasonable certainty of no harm" standard for
tolerances, stated that EPA should implement this new
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standard through the 1-in-l million-lifetime riskiest.
which EPA had used prior to 1996. H.R. Rep. No.
104-669, pt. 2, at 41 (1996).
36 CERCLA requires that EPA develop and regularly
revise the NCP, which consists of regulations that
provide the organizational structure and procedures
for preparing for and responding to releases of
hazardous substances, pollutants and contaminants.
42 U.S.C. § 9605(a); 40 CFR part 300.
37 Through the Hazard Ranking System regulations, EPA
has established the criteria for determining response
priorities for releases or threatened releases. EPA uses
the Hazard Ranking System to determine whether
a site should be placed on the National Priority List
(NPL), which is "the list, compiled by EPA ... of
uncontrolled hazardous substance releases in the
United States that are priorities for long-term remedial
evaluation and response." 42 U.S.C. § 9605(a)(8)(B);
40 CFR 300.5.
3« 42 U.S.C. § 9621(b)(l). Note that EPA NCP
regulations build on the statutory requirements
regarding remedy selection. The EPA NCP regulations
require a comprehensive risk assessment for a
Superfund site as part of investigations that follow
listing on the NPL of uncontrolled wastes sites as
Superfund sites. 40 CFR 300.430(a)(2), 300.430(d)(l);
see U.S. EPA, Office of Solid Waste and Emergency
Response, Rules of Thumb for Superfund Remedy
Selection, EPA 540-R-97-013, at 2 (1997), available at
http ://www. epa. gov/superfund/policy/remedy/rules/
rulesthm.pdf (last accessed Feb. 14, 2012).
39 CERCLA requires the selection of remedies that
provide "cost-effective response. In evaluating the
cost effectiveness of proposed alternative remedial
actions, the President shall take into account the total
short- and long-term costs of such actions, including
the costs of operation and maintenance for the entire
period during which such activities will be required."
42 U.S.C. § 962l(a). Further, in assessing alternative
remedial actions, EPA must consider, at a minimum.
long-term maintenance costs and the potential for
future remedial action costs, if the alternative remedial
action were to fail. 42 U.S.C. § 9621(b)(l).
40 "The President may select a remedial action meeting
the requirements of paragraph (1) that does not attain
a level or standard of control at least equivalent
to a legally applicable or relevant and appropriate
standard, requirement, criteria, or limitation ... if
the President finds that... compliance with such
requirement at that facility will result in greater risk
to human health and the environment than alternative
options." 42 U.S.C. § 9621(d)(4)(B).
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United States
Environmental Protection
Agency
PRESORTED STANDARD
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