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The Foundation for Global Action on
Persistent Organic Pollutants:
A United States Perspective
I
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The Foundation for Global Action on
Persistent Organic Pollutants:
A United States Perspective
Office of Research and Development
Washington, DC 20460
EPA/600/P-01/003F
NCEA-I-1200
March 2002
www.epa.gov
Disclaimer
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
Cover page credits: Bald eagle, U.S. FWS; mink, Joe McDonald/Corbis.com; child,
family photo, Jesse Paul Nagaruk; polar bear, U.S. FWS; killer whales, Craig Matkin.
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Contributors vii
Executive Summary ix
Chapter 1. Genesis of the Global Persistent Organic Pollutant Treaty 1-1
Why Focus on POPs? 1-2
The Four POPs Parameters: Persistence, Bioaccumulation,
Toxicity, Long-Range Environmental Transport 1-5
Persistence 1-5
Bioaccumulation 1-6
Toxicity 1-7
Long-Range Environmental Transport 1-7
POPs History—Cut Short 1-8
UNEP Global POPs Negotiations 1-10
Science Clarifications—Separating Facts from Assumptions 1-12
References 1-15
Chapter 2. Profiles of the POPs 2-1
1. Intentionally Produced POPs: Pesticides 2-3
Cyclodiene Insecticides 2-3
Dichlorodiphenyl trichloroethane (DDT) 2-7
Toxaphene 2-11
Hexachlorobenzene 2-11
2. Intentionally Produced POPs: Industrial Chemicals 2-13
Polychlorinated Biphenyls (PCBs) 2-13
3. Byproduct POPs 2-15
Polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated
dibenzofurans (PCDF) 2-15
References 2-18
Appendix. Selected Federal Sites for POPs Toxicity Information 2-22
Chapter 3. Persistent Organic Pollutant Residues and Their
Effects on Fish and Wildlife of the Great Lakes 3-1
Introduction 3-1
Fish 3-3
Lake Trout 3-4
Birds 3-6
Bald Eagles 3-7
Colonial Fish-Eating Birds 3-9
Mammals 3-10
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Contents
Conclusions 3-12
References 3-13
Chapter 4. Persistent Organic Pollutants in the Great Lakes:
Human Health Considerations 4-1
Introduction 4-1
Historical Background on POPs Exposure Studies in the Great Lakes 4-2
Identification of Critical Great Lakes Pollutants 4-2
ATSDR Great Lakes Human Health Effects Research Program 4-3
Epidemiological Data 4-4
Reproductive Effects 4-5
Neurodevelopmental Effects 4-6
Other Cognitive and Systemic Health Effects 4-8
Fish and Wildlife Advisories 4-9
Conclusion 4-12
References 4-12
Chapter 5. Alaska—At Risk 5-1
Why Alaska Is at Special Risk 5-2
POPs Transport to Alaska 5-4
Atmospheric Transport 5-4
Hydrologic Transport 5-5
Migratory Species 5-5
POPs Levels in Alaska 5-6
Wildlife Levels 5-7
Bald Eagle 5-7
Peregrine Falcon 5-8
Killer Whale 5-9
Sea Otter 5-10
Species Consumed by Humans 5-11
Beluga 5-11
Bowhead Whale 5-12
Seals 5-12
Steller Sea Lion 5-13
Salmon 5-14
Polar Bear 5-15
Native Peoples of Alaska 5-15
POPs Levels in Alaska Natives 5-17
Ongoing POPs Research in Alaska 5-18
Conclusion 5-19
References 5-20
Chapter 6. Accumulation and Effects of Persistent Organic Pollutants in
Marine Ecosystems and Wildlife 6-1
Introduction 6-1
Transport of POPs and the Role of Oceans as Sinks 6-1
Status and Trends of POPs in North American Marine Ecosystems 6-2
Routes of Exposure of Marine Mammals and Seabirds to POPs 6-3
IV
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Contents
Adverse Effects on Wildlife 6-4
Inshore Birds 6-5
Offshore Birds 6-7
Marine Mammals 6-8
Other Marine Mammals: Pinnipeds, Manatees, and Otters 6-11
Summary and Conclusions 6-12
References 6-13
Chapter 7. Long-Range Environmental Transport of Persistent
Organic Pollutants 7-1
Introduction 7-1
Atmospheric Transport of Pollutants to the United States 7-2
Atmospheric Chemistry of POPs 7-4
Global Distillation of POPs 7-6
Calculating and Modeling Atmospheric Transport of POPs 7-8
POPs Transport in Water 7-11
POPs Transport by Migratory Animals 7-12
Monitoring and Modeling POPs Trends 7-13
References 7-13
Chapter 8. Contemplating POPs and the Future 8-1
General Worldwide Growth Projections 8-2
Population Growth 8-2
Economic Activity 8-3
Agricultural Output 8-3
Energy Consumption 8-4
Sector-Specific Growth Projections 8-4
Housing Starts and Termite Control 8-4
Municipal Waste Generation and POPs Byproducts 8-5
Industrial Processes and POPs Byproducts 8-6
Summary 8-6
References 8-7
Chapter 9. The Addition of Chemicals—A Living Agreement 9-1
The Addition Process 9-2
Scientific Foundation for Adding Chemicals 9-3
Screening Criteria 9-3
Persistence 9-3
Bioaccumulation 9-5
Long-Range Environmental Transport 9-7
Adverse Effects/Toxicity 9-10
The Risk Profile 9-11
Risk Management Options 9-11
The Decision 9-12
The Future 9-12
References 9-12
Appendix A. Transport Pathways A-l
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Bruce D. Rodan
Chapter 1. Genesis of the Global Persistent Organic Pollutant Treaty
Bruce D. Rodan
Chapter 2. Profiles of the POPs
Kathleen R. Walker, Susan Y. Euling
Chapter 3. Persistent Organic Pollutant Residues and Their Effects on Fish and Wildlife
of the Great Lakes
John P. Giesy, Paul D. Jones, Kurunthachalam Kannan, Alan L. Blankenship
Chapter 4. Persistent Organic Pollutants in the Great Lakes:
Human Health Considerations
Heraline E. Hicks, Christopher T. De Rosa
Chapter 5. Alaska—At Risk
Carl M. Hild, Kimberlee B. Beckmen, James E. Berner, Lin Kaatz Chary, Kari J.
Hamrick, Philip C. Johnson, Peggy M. Krahn, Suzanne K. M. Marcy, Craig O. Matkin,
Carol H. Rubin, Marianne G. See, Michael J. Smolen, Lori A. Verbrugge
Chapter 6. Accumulation and Effects of Persistent Organic Pollutants in Marine
Ecosystems and Wildlife
Paul D. Jones, Kurunthachalam Kannan, Alan L. Blankenship, John P. Giesy
Chapter 7. Long-Range Environmental Transport of Persistent Organic Pollutants
Joseph P. Pinto
Chapter 8. Contemplating POPs and the Future
Hugh M. Pitcher
Chapter 9. The Addition of Chemicals—A Living Agreement
Bruce D. Rodan, David W. Pennington, Noelle Eckley, Robert S. Boethling
Acknowledgment: The authors wish to thank the many internal EPA peer reviewers, the
external peer review panel (Drs. Peter deFur, Derek Muir, Bernard Weiss), and the mem-
bers of the public who submitted comments for their valuable insights, suggestions, and
additions.
VII
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Persistent organic pollutants (POPs) are a small
group of organic chemicals exhibiting the com-
bined properties of persistence, bioaccumulation,
toxicity, and long-range environmental transport.
This small group of pollutants encapsulates the
genesis and development of pollution awareness
in the United States. These are the pollutants
that Rachel Carson described in Silent Spring,
that contaminated Agent Orange during the
Vietnam War, and that contributed to Love Ca-
nal, Times Beach, and the pollution of the Great
Lakes. Legislative, regulatory, legal, and volun-
tary actions in the United States have eliminated
domestic production of many POPs as pesticides
and industrial chemicals, and have greatly re-
duced their emissions as byproducts. Yet, al-
though uses and levels in the lower 48 United
States have stabilized or declined, elevated levels
are now being found in what had been thought
pristine, uncontaminated environments, notably
in the Arctic and remote oceans. Air and water
movement are transporting POPs across interna-
tional borders to these remote locations, where
they can be elevated to potentially toxic levels
through biomagnification in the food chain.
Most poignantly, the first exposure of offspring
may be through a loading dose of toxicant to the
fetus or in milk, during the most sensitive period
of development.
On May 23, 2001, the United States joined 90
other nations in signing the Stockholm Convention
on Persistent Organic Pollutants. Under the Con-
vention, countries commit to reduce and/or elimi-
nate the production, use, and release of the 12
POPs of greatest concern to the global commu-
nity and to establish a mechanism by which addi-
Bald eagle, chick, and egg. POPs impacts have been
particularly severe on the reproductive success of birds
of prey.
Photo: D. Best
tional chemicals may be added to the treaty in
the future. This report is directed toward edu-
cating decisionmakers, academia, and the public
on the science underpinning this global action,
focusing on the 12 priority substances or sub-
stance groups, commonly known as the "dirty
dozen."
IX
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Executive Summary
aldrin
dieldrin
endrin
DDT
chlordane
heptachlor
mirex
toxaphene
hexachlorobenzene (HCB)
polychlorinated biphenyls (PCBs)
polychlorinateddibenzo-p-dioxins
polychlorinated dibenzofurans
The report provides an overview of the human
and ecological risks posed by POPs to U.S. eco-
systems and citizenry. Recognizing the immense
technical literature on these POPs, the report
focuses on the most salient topics, while pointing
to additional literature sources for readers requir-
ing further information. The chapters are based
on the following general themes:
•;K Chemical profiles: A narrative introduction is
provided for each of the 12
POPs. This is accompanied
by tables summarizing
important chemical proper-
ties and the regulatory
history covering production
and use in the United
States. The narrative high-
lights selected toxicological
issues not directly discussed
elsewhere in this report.
For instance, the agricul-
tural problems caused by
prolonged, indiscriminate
toxicity from the cyclodiene
POPs insecticides are noted
(e.g., dieldrin), along with
the availability over time of
improved chemical, physi-
cal, and integrated alterna-
tives for pest management.
For DDT, particular atten-
tion is drawn to the need
to balance malaria vector
control in some developing
countries with epidemio-
Alaska native hunter and boat; a way of life
for many communities.
Photo: U.S. Department of the Interior
logical evidence of increased preterm human
births associated with DDT exposure, and its
demonstrated adverse ecological impacts.
Notable in this context, the Stockholm Con-
vention provides for continued DDT use for
disease vector control in countries registering
such a need, where safe and cost-effective
alternatives are not available. This use is
subject to World Health Organization recom-
mendations and guidelines, which allow indoor
application only.
Human and ecological effects in the United
States: Historical and contemporary data are
summarized demonstrating why POPs gained
notoriety in the United States and internation-
ally. Two regions are highlighted: the Great
Lakes and marine ecosystems. In the Great
Lakes, the contribution of POPs, especially DDT,
to eggshell thinning and population declines in
raptors (e.g., bald eagles, osprey, falcons) is well
known. PCBs and polychlorinated dioxins and
furans have combined to affect Great Lakes fish
populations (blue-sac dis-
ease), fish-eating birds
(GLEMED syndrome), and
mammalian reproductive
success, especially in mink.
For humans, POPs intakes
continue through the con-
sumption of Great Lakes
sport fish. Epidemiological
evidence in these popula-
tions has associated PCB
levels in mothers with ad-
verse neurodevelopmental
outcomes in their children.
POPs effects have also been
demonstrated in marine eco-
system bird and marine mam-
mal populations, both in
coastal areas and in remote
oceans. In the early 1970s,
brown pelican populations on
U.S. coasts were brought to
the edge of extinction follow-
ing DDT-induced eggshell
thinning, principally mediated
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Executive Summary
Birds on remote Midway atoll in the north Pacific are
exposed to POPs.
Photo: NASA
through its long-lived
metabolite DDE.
Contemporary el-
evated levels of PCBs
and dioxins accumu-
lated in albatross on
Midway Atoll in the
remote North Pacific
Ocean may be inter-
fering with their re-
productive success.
These findings from
the Great Lakes and
marine ecosystems
demonstrate that it is
possible to sufficiently
contaminate environ-
ments with POPs residues to cause adverse
effects on a regional and global scale, along
with the prolonged and continuing nature of
these impacts. The experience is also one of
hope, in that controls on the production, use,
and release of POPs can, and have, resulted in
reduced environmental concentrations and
wildlife recovery. The bald eagle saga offers
an inspiring metaphor. Once nearly extinct in
the lower 48 United States, bald eagle popula-
tions have recovered dramatically with the
cessation of DDT use in the United States, yet
the reproductive impacts linger.
Long-range transport of POPs: POPs move
to regions such as the Great Lakes, marine
ecosystems, and the Arctic through long-range
environmental transport in air, water, and
migratory species. This transboundary move-
ment occurs principally through the atmo-
spheric pathway, either on suspended particles
or through a process of global distillation and
cold condensation. Global distillation results
from the semivolatile nature of some POPs,
where they can be present in more than one
phase in the atmosphere, either as gases or
attached to airborne particles. Because of the
normal decrease of temperature with increas-
ing latitude, compounds in the vapor phase
will tend to condense on surfaces as they are
transported northward by winds associated
with passing weather
systems. This cold
condensation results in
a net transport of POPs
from lower latitudes to
high latitudes (polar
regions) in a series of
jumps. The different
affinities of POPs for
soil particles, water,
and/or lipid molecules,
and their rate of volatil-
ization, determine the
pathway and time
course each chemical is
likely to take in its
journey through the
environment.
POPs in Alaska: Risks to Arctic environments
and indigenous human populations were cen-
tral to negotiating the Stockholm Convention
on POPs. For the United States, many of the
physical, climatic, and social aspects that make
Alaska unique — particularly for the indig-
enous population — also make this region
peculiarly prone to risks from global POPs.
Alaska is downwind and geographically close
to continuing sources of POPs production and
use in Asia, where populations and economic
growth are expanding rapidly. The Alaskan
climate facilitates the deposition of POPs,
delays their degradation through environmental
processes, and places unusual stresses on
ecosystems. Fat becomes the currency of life
in the harsh Arctic environment for both wild-
life and humans, serving as the ideal medium
for transferring and magnifying the concentra-
tions of lipophilic POPs between species and
up the food chain.
Previously pristine in remote areas, all of
Alaska's environmental media and species now
contain measurable levels of POPs. However,
POPs levels in Alaska are generally low com-
pared with the lower 48 United States. Accom-
panying these comparatively low levels are iso-
lated examples of elevations that serve as a
cautionary warning in the absence of interna-
XI
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Executive Summary
tional action. DDT and PCB levels in transient
Alaskan killer whales are as high as those
found in highly contaminated east coast dol-
phins. On Kiska Island in the Aleutians, DDT
levels in bald eagle eggs approach effect levels
seen in the Great Lakes. And, serum concen-
trations of DDT and chlordane in a limited
sample of Alaska Natives underscore their
proximity to areas of continuing production
and use internationally. It is important to
emphasize, however, that there are no known
POPs levels at this time in Alaska that should
cause anyone to stop consuming locally ob-
tained, traditional foods or to stop breast-
feeding their children. Current information
indicates that the risks associated with a sub-
sistence diet in Alaska are low, whereas the
benefits of this diet and breastfeeding children
are well documented. Further investigation
and assessment are needed for specific spe-
cies and foods in traditional diets, and to
broaden the database across Alaskan
communities.
-# What might the future hold in the absence of
POPs controls? The passage of time is central
to evaluating the merits of the Stockholm Con-
vention. Emission scenario models forecast
large increases in the scale of worldwide eco-
nomic activity over the next half-century, with
overall economic activity predicted to increase
about fourfold in the "business as usual" sce-
nario. The human population is predicted to
increase to around 9 billion persons. The large
majority of increases will occur in developing
countries. Although different model inputs lead
to different results, all projections share a com-
mon future of much higher total economic activ-
ity, and hence of potential uses and emissions
of POPs in the absence of active control poli-
cies and alternatives.
The United States is not alone in having experi-
enced POPs problems, with many countries suf-
fering local and transboundary pollution effects.
In response, the United States has signed inter-
national agreements on persistent toxic sub-
stances under the Great Lakes Binational Toxics
Strategy (US, Canada); the North American
Agreement on Environmental Cooperation (US,
Canada, Mexico); and the UNECE Long-Range
Transboundary Air Pollution POPs Protocol (US,
Canada, Western and Eastern Europe, Newly
Independent States, Russia). The consensus for
global action on POPs under the Stockholm Con-
vention is commensurate with the extent of the
pollution and the need to include all countries in
the solution. To this end, the Convention con-
tains the following central elements:
i*c Measures to eliminate or restrict the produc-
tion, use, and trade of intentionally produced
POPs
-£ Development of action plans to address the
release of byproduct POPs, along with the obli-
gation to use best available techniques to reduce
byproduct emissions from newly constructed
facilities in specified major industrial source
categories
i*c Measures to reduce or eliminate POPs releases
from stockpiles and wastes
-& Technical and financial assistance to develop-
ing countries, and countries with economies in
transition, to implement their obligations under
the Convention
-£ Science-based criteria and procedures for the
addition of new POPs chemicals
The Stockholm Convention will enter into force
following ratification by 50 nations. The Con-
vention is aimed at protecting human health and
the environment from POPs chemicals on a glo-
bal scale. Through implementation of the Con-
vention, nations have the opportunity to make
POPs a relic of the 20th century, and a warning
from history for the 21st century.
XII
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tach day the resilience of the Earth offers hu-
manity a new beginning by mitigating the pollu-
tion and wastes of yesterday. Through wind and
water, pollutants are dispersed and diluted;
through chemical and biological degradation,
toxic substances are eliminated; and through the
fidelity of DNA replication, life begins anew.
But for a small group of persistent organic pollut-
ants (POPs), natural processes and ecosystem
services have proven inadequate to rectify, and
in some cases have contributed to, environmental
contamination. The resistance of POPs to deg-
radation and their environmental persistence
serve as a foundation for prolonged and dissemi-
nated adverse effects. Air and water move
POPs far from their sites of release to the envi-
ronment, including to previously pristine locations
such as the Arctic. The low levels of POPs
reaching remote locations can then be elevated
to potentially toxic levels through biomagni-
fication in the food chain. And, most poignantly,
the first exposure of offspring may be through a
loading dose of toxicant to the fetus or in milk,
during the most sensitive period of development.
PCB concentrations are elevated in Aleutian Island sea
otter populations.
Photo: U.S. Fish and Wildlife Service
It is to this group of substances—the persistent
organic pollutants—that this technical report is
addressed.
The report summarizes the science underpinning
contemporary action on POPs, focusing on the
12 substances or substance groups prioritized for
global action in the recently signed Stockholm
Convention on Persistent Organic Pollutants,
developed under the auspices of the United
Nations Environment Programme (UNEP). These
12 substances, the "dirty dozen," are:
•-*; Pesticides: dieldrin, aldrin, endrin, chlordane,
heptachlor, DDT, toxaphene, mirex
# Industrial chemicals: polychlorinated biphenyls
(PCBs; also a byproduct), hexachlorobenzene
(HCB; also a pesticide and byproduct)
•-*; Byproducts: polychlorinated dibenzofurans,
polychlorinated dibenzo-p-dioxins (dioxin)
The report is directed toward educating decision-
makers, academia, and the public on the founda-
tion and relevance to the United States of the
Stockholm Convention on POPs. The report
consolidates and summarizes the large volumes
of data developed on these substances over de-
cades of scientific concern and regulatory experi-
ence, as published in multiple source documents
from individual peer-reviewed literature, through
single-chemical profiles, to multivolume risk
assessments. Its objective is to provide an over-
view of the human and ecological risks posed by
POPs to U.S. ecosystems and citizenry. Empha-
sis is placed on making the document easily
readable, while maintaining its technical accuracy
and balance. To this end, citations are provided
to more comprehensive and detailed literature
for those seeking a more complete elaboration of
technical issues.
7-7
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Genesis of the Global POPs Treaty
Public concern and scientific and regulatory ef-
forts regarding this small group of pollutants
encapsulate the genesis and development of
environmental pollution awareness in the United
States. These are the pollutants that Rachel
Carson wrote about in Silent Spring (Carson,
1962), that contaminated Agent Orange during
the Vietnam War, and that contributed to Love
Canal, NY, Times Beach, MO, and numerous
other pollution episodes. All 12 substances pri-
oritized under the Stockholm Convention are now
deregistered, banned, or out of production in the
United States, or their emissions have undergone
major reductions. Yet their effects are still felt
through a legacy of past pollution, continuing
emissions, and movement across international
borders.
For the nine organochlorine pesticides (including
hexachlorobenzene as a fungicide), the extent of
adverse human health and/or ecological effects
^ISP* 13SP
^ ^ - -""''. 4»tY. jii. ; —•* '•
Wif* - » '•- " -.-•••»* S?5 "--,f* •">•
fcT*i ''.^ft ".**. '- " ' _**&*!
-,; » -..-- v- -*«^>'*r
Poor storage of donated DDT in Zanzibar.
Photo: R. Hedlund, USAID
Dieldrin-containing drums in Niger.
Photo: Janice Jensen
led to the withdrawal of all registered uses in the
United States during the 1970s-1990s, either by
the U.S. Environmental Protection Agency (EPA)
or voluntarily by the registrant. Production of the
last of these, heptachlor, has ceased and its
registration was voluntarily cancelled in 2000.
Because U.S. pesticide laws are based on regis-
trations for specific uses, problem chemicals are
dealt with through withdrawal of these registra-
tions, rather than bans on production. The net
effect of these actions is that there is currently
no production of any of the POPs in the United
States for sale domestically or internationally,
except for laboratory-scale research consistent
with the requirements of the Stockholm Conven-
tion.
For polychlorinated biphenyls (PCBs), the magni-
tude of environmental problems was central to
the passage of the Toxic Substances Control Act
(TSCA). PCB production was banned under this
legislation in 1979, although production ceased
prior to this date. Existing PCBs in electrical
equipment must be prevented from entering the
environment and destroyed at the end of the
equipment's service life. Polychlorinated
dibenzo-p-dioxins and polychlorinated
dibenzofurans, better known as "dioxins," have
been controlled through a variety of means, prin-
cipally emission controls on incinerator sources,
process changes to remove elemental chlorine
from pulp and paper production, and the
1-2
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Genesis of the Global POPs Treaty
deregistration of contaminated herbicides such as
2,4,5-trichlorophenoxyacetic acid (2,4,5-T; a
constituent of Agent Orange).
The breadth of POPs pollution that led to these
U.S. regulatory actions is still evident in contem-
porary environmental concentrations. POPs
pollution has touched every region of the United
States, as illustrated by the geographic distribu-
tion of DDE (a long-lived toxic metabolite of
DDT (ng/g)
. 1-96
* 97-376
377-90S
• \tfx
*€* N
" \ /
-O^H/
\
<• 7
O 537-1778
1779-6323
Figure 1-1. 1986-1998 mean sum-DDT and sum-PCB
concentrations in coastal mussels (dry weight) collected
by the National Oceanic and Atmospheric Administration
(NOAA) through its ongoing Status and Trends Mussel
Watch Program, http://ccma.nos.noaa.gov. Data courtesy
of Tom O'Connor, NOAA. See also trends discussion in
Chapter 6.
D American Samoa = 1
D Guam
D Virgin Islands
D Puerto Rico
D States issuing advisory (37)
• Statewide Lake Advisories
A Statewide Rwer Advisories
« Statewide Coastal Marine Advisories
Figure 1-2. 1998 fish consumption advisories reported
for po/ych formated biphenyls (PCBs) to the U.S. EPA by
states, territories, and Native American tribes. See Chap-
ter 4 for further details on fish advisories. U. S. EPA 1999.
DDT) and PCB concentration elevations in
coastal mussels (Figure 1-1), PCB fish advisories
(Figure 1-2), and contemporary measurements of
atmospheric dioxin levels in nonurban locations
across the United States (Figure 1-3). Impacts
on the Great Lakes (Chapters 3, 4) and marine
ecosystems (Chapter 6) are highlighted in this
report as examples of POPs pollution exposures
and effects, along with a summary of the
existing science on POPs concentrations and
risks in Alaska (Chapter 5). Many more sites of
POPs contamination are scattered across the
United States, but these cannot be detailed here
because of space constraints. One such example
is Lake Apopka in Florida, where high levels of
several POPs (principally DDE) and other
pollutants (Figure 1-4) have been postulated as
causing reproductive impairment and male
genital abnormalities in alligators following
embryonic exposure, although the specific causal
agent(s) remains uncertain (Guillette et al.,
1999).
The extent to which POPs remain problematic is
also manifest through continuing regulatory and
policy initiatives, both domestically and in inter-
national fora in North America. Domestically,
the EPA is engaged in a variety of initiatives on
persistent, bioaccumulative, toxic (PBT) chemi-
1-3
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Genesis of the Global POPs Treaty
M WHO TEQ PCB
(fg/m3) % of Total
S3 WHO TEQ CDF/CDD
(fg/m3) % of Total
Annual Average/
of Total WHO
TEQ (fg/m3)
Figure 1-3. Average atmospheric concentrations of
dioxin TEQ (from PCDDs, PCDFs, coplanar PCBs) in
femtograms (1015 grams) per cubic meter for the year
2000, collected by the National Dioxin Air Monitoring
Network (NDAMN). Site locations listed after refer-
ences. Source: David Cleverly, U.S. EPA
Sites: 1 - Penn Nursery, PA; 2 - Penn Nursery, PA, QA duplicate;
3 - Clinton Crops, NC; 4 - Everglades National Park, FL; 5 - Lake
Dubay, WI; 6 - Monmouth, IL; 7 - McNay, IA; 8 - Lake Scott, KS;
9 - State Park West of Tulsa, OK; 10 - Arkadelphia, AR;
11 - Bennington, VT; 12 - Jasper, NY; 13 - Beltsville, MD;
14 - Caldwell, OH; 15 - Oxford, OH; 16 - Dixon Springs, IL;
17 - Quincy, FL; 18 - Stennis Space Center, MS - insufficient data
in Yr. 2000; 19 - Padre Island, TX; 20 - Fond du Lac Indian
Reservation, MN; 21 - North Platt Agricultural Experiment
Station, NE; 22 - Goodwell Research Station, OK; 23 - Big Bend
National Park, TX; 24 - Grand Canyon National Park, AZ;
25 - Theodore Roosevelt National Monument, ND; 26 - Craters of
the Moon National Park, ID; 27 - Chiricahua National Park, AZ;
28 - Proposed Dairy Reseach Facility, CA; 29 - Hyslop Farm, OR;
30 - Lake Ozette, WA; 31 - Fort Cronkite, San Francisco, CA;
32 - Craig, AK, recently operational; 33 - Trapper Creek, AK,
recently operational.
Figure 1-4. A. Mean serum levels of POPs in juvenile
male and female alligators from three different lakes in
the same drainage in Florida (Guillette et ai, 1999).
B. A yearling alligator swimming in the eutrophic water
of Lake Apopka.
Photo: Howard K. Suzuki
Binational Toxics Strategy
Canada
and
United States
-
cals. PBTs encompass a somewhat broader do-
main than POPs, including metals, whereas
POPs are limited to organic substances (i.e., con-
taining carbon). Domestic activities include the
EPA's PBT program to coordinate action regard-
ing these pollutants (www.epa.gov/pbt), the
Toxics Release Inventory (TRI) PBT reporting re-
quirements under the Emergency Planning and
Community Right-To-Know Act (EPCRA)
(www.epa.gov/tri/pbtrule.htm), and the
prioritization accorded PBT parameters when
evaluating new chemical notifications under the
Toxic Substances Control Act (TSCA) and when
registering pesticides under the Federal Insecti-
cide, Fungicide, and Rodenticide Act (FIFRA).
Internationally, the Great Lakes Binational Strat-
egy with Canada prioritizes primary and second-
ary lists of substances slated for "virtual elimina-
tion" (www.epa.gov/glnpo/p2/bns.html). Central
to these lists are the 12 priority POPs listed in
the Stockholm Convention. With Mexico, under
the environmental side agreement of the North
American Free Trade Agreement (NAFTA), the
United States and Canada have focused their
Safe Management of Chemicals (SMOC) efforts
on PBTs (tuLULU.cec.org). Action plans have been
developed for DDT, PCBs, and chlordane, as well
as mercury, and are under development for diox-
ins, furans, and hexachlorobenzene.
mmission for Environmental Coooeration
ik Lijiu hiiEib
tiLvirunincnr,
1-4
-------
Genesis of the Global POPs Treaty
Contributing to the difficulties in eliminating
some POPs are their advantages in the industrial
and building sectors. PCBs made excellent di-
electric fluids in electrical capacitors and trans-
formers because they are highly resistant to deg-
radation and fire. These same properties
contribute to their persistence in the environment
and biological organisms. A single application of
chlordane, an organochlorine termiticide, pro-
vides household termite protection for years.
Unfortunately, not all the chlordane stays where
it is applied, and it may continue to
bioaccumulate far from basement soil and injure
or kill creatures for which it was not intended.
DDT's ability to repel and injure or kill malaria-
carrying mosquitoes can provide several months
of household protection, yet ultimately DDT is
mobilized and spread outside of the immediate
area of application. The benefits of DDT for
malaria control, principally due to its persistence,
low cost, and past success, remain a major con-
sideration when balancing public health needs
with environmental concerns.
A suite of four characteristic parameters distin-
guish POPs from the multitude of other organic
chemicals:
Persistence
Persistence is the propensity of a substance to
remain in the environment by resisting chemical
and biological degradation, particularly the ef-
fects of microbial processes. Persistence is best
represented as the degradation of a POP to a
non-POP chemical, rather than as declining envi-
ronmental concentrations that combine degrada-
tion with loss due to dispersion. Persistence is
often measured as a half-life, the time (hours,
days, months, or even years) necessary for half
the chemical to be degraded. Reliance on half-
life measures assumes first-order kinetics, where
the amount degraded in a fixed period of time is
a constant proportion of the amount present
initially, i.e., Ct = C0 e~rt, where C0 and Ct are
concentrations at times zero and t, and r is the
rate constant for degradation (Figure 1-5). The
first-order kinetics assumption may not always
apply where early degradation is more rapid,
delayed degradation is enhanced through bacte-
rial acclimation and selection, or chiral (mirror
image) molecules may be preferentially de-
graded. The degradation product may also ex-
hibit POPs characteristics. Half-life values in the
different air, soil, water, and sediment media
have been included in most POPs screening
criteria (see Chapter 9, Table 9-1). These half-
life values are considered pragmatically useful for
screening chemicals, but are recognized as over-
simplifying the persistence of chemicals in the
environment (Klecka et al., 2000). Persistence
screening values for the Stockholm Convention
are based on 2 months in water or 6 months in
soil or sediment, with a 2-days screening crite-
rion for air transport.
Environmental degradation in the atmosphere
occurs principally from reaction of the POP with
hydroxyl radicals (OH). The levels of hydroxyl
radicals in the air vary considerably with geo-
graphic location and time of day and year. For
instance, hydroxyl levels are essentially zero in
the Arctic atmosphere during winter and gener-
ally decline with increasing latitude. Other atmo-
spheric POPs degradation processes include pho-
tolysis (light-induced degradation) and reaction
First-Order Kinetics
Half-life 6 months
395 730
Time - Days
Figure 1-5. First-order decay kinetics diagram.
1-5
-------
Genesis of the Global POPs Treaty
with ozone and nitrogen oxides. In soil, water,
and sediment, microbial degradation is the pre-
dominant mechanism. The rate of degradation
depends on the types of bacteria present, their
concentration, induction relevant to the chemical
undergoing degradation, and ambient environ-
mental conditions such as temperature, moisture,
and substrate availability. Other processes in-
clude photolysis, hydrolysis, and chemical reac-
tion. Details of technical considerations in deriv-
ing and using persistence data are contained in
the report of a Society of Environmental Toxicol-
ogy and Chemistry (SETAC) Pellston workshop,
focusing on POPs persistence and long-range
transport issues (Klecka et al., 2000).
Bioaccumulation is the phenomenon whereby a
chemical reaches a greater concentration in the
tissues of an organism than in the surrounding
environment (water, sediment, soil, air), princi-
pally through respiratory and dietary uptake
routes. For example, if the environment in
which a fish lives contains 1 ug free chemical/kg
of water, and the fish's body contains 5,000 ug
chemical/kg body weight, this would equate to a
whole-body bioaccumulation factor (BAF) of
5,000 (i.e., the Stockholm Convention screening
criterion value). The magnitude of
bioaccumulation is driven by the hydrophobicity,
or water insolubility, of the chemical, principally
operating through the ability of a species to
eliminate the chemical from its body by excretion
and/or metabolism. The terms bioaccumulation,
bioconcentration, and biomagnification are vari-
ants of this same concept. Bioaccumulation
factors measure the preferential accumulation of
a chemical in a living organism through all routes
of uptake with respect to concentrations in the
organism's exposure environment (water, sedi-
ment, soil). The term "bioconcentration factor"
(BCF) is used when the bioaccumulation factor is
based exclusively on uptake from water in labo-
ratory studies, using species (most commonly
fish) maintained in a known concentration of
pollutant but fed an uncontaminated diet.
Biomagnification relates to the most highly accu-
mulative substances (many of the POPs), where
the concentration of the chemical in an organism
exceeds that predicted for equilibrium of the
organism with its diet, the concentration having
been "magnified" in species higher up the food
chain (Figure 1-6).
BCF/BAF values can be reported either in rela-
tion to the whole-body weight of the test species
or in a more standardized manner related to the
lipid (or fat) content of the animal, usually a fish.
These two measures can be quantitatively linked
through the fat content of the animal because
the POPs are concentrated in the fatty portions
of tissues. This relationship is often simplified by
assuming a standard fish fat content to facilitate
comparison between chemicals in different study
protocols and species, known as lipid normaliza-
tion (e.g., 3.1% lipid in the case of the Great
Lakes Water Quality Assessment for trophic level
3 fish).
A common surrogate for calculating BCF/BAF
values is the octanol-water partition coefficient
(Kow). This ratio reflects the preferential accu-
mulation of a substance in an organic medium
(n-octanol) compared with water. To illustrate, in
a cup containing half n-octanol and half water,
this is the amount of a chemical placed in the
cup that would dissolve in the n-octanol divided
by the amount dissolving in the water. The Kow
is now most often calculated using chemical
models. It should be noted that mathematical
Figure 1-6. Simple biomagnification diagram.
1-6
-------
Genesis of the Global POPs Treaty
formulae linking the Kow with BCF/BAF values
do not apply where there is active metabolism of
the substance, or for large molecules, and are
generally not applicable to organometals. Addi-
tional detail on bioaccumulation in aquatic envi-
ronments is available in the U.S. EPA Great
Lakes Water Quality Criteria documents (U.S.
EPA, 1995).
A principal tenet of toxicology is that the dose
makes the poison (Paracelsus, 1493-1541), a
concept elaborated upon more recently as knowl-
edge has increased on the complexity and timing
of dose-response relationships. The toxicity of a
substance can be reported in a variety of ways,
such as acute (short-term) or chronic (long-term)
effects, lethal or effective dose levels (LD50 or
ED50, the dose that will kill or affect 50% of test
animals), or tissue levels associated with an ad-
verse effect. Whereas certain toxic effects and
levels may be easily detected and quantified in
laboratory settings, their measurement in the
natural environment is considerably more diffi-
cult. In field situations, the animal's environ-
ment is impossible to control.
This situation is similar to the difficulties
experienced with human epidemiological studies.
Multiple substances may combine to form a
"toxic soup" from which individual chemical
contributions can be difficult to disentangle. A
corollary of multiple simultaneous exposures is
that the cumulative toxicity risk is likely to be
greater than when individual chemicals are
evaluated in isolation. Furthermore, the low-level
effects of interest in field situations may be
subtle and difficult to measure, yet vital to
species survival. For example, subtle POPs-
induced neurological impairment may not cause
overt effects in a caged, fed, and protected
animal, but may be of dire consequence in the
complex and dangerous natural environment.
Difficulties also occur when attempting to
transpose laboratory toxicity data, generally
measured as daily dose, to field situations where
the metric is tissue concentration of a toxic
substance and daily doses cannot be measured.
For a further detailed discussion of wildlife toxi-
cology and the effect levels pertinent to POPs
impacts on wildlife, see Beyer et al. (1996).
Toxicity data on POPs pertinent to humans can
be obtained from online databases maintained by
the National Library of Medicine
(www.nlm.dhhs.gov; Hazardous Substances
Data Bank), the EPA's Integrated Risk Informa-
tion System (IRIS) database (www.epa.gov/iris),
and the Agency for Toxic Substances and Dis-
ease Registry (ATSDR) Toxicological Profiles
(www.atsdr.cdc.gov).
There would be little need for a global treaty if
POPs remained close to their sites of release.
However, on a dynamic planet the forces of air
and water, along with the migratory behavior of
certain species, move these pollutants to remote
locations (see Chapter 7 for details). A major
impetus for the global POPs negotiation was the
finding of POPs contamination in the Arctic,
thousands of miles from their presumed sites of
release to the environment. Figure 1-7 shows
the intermittent transport of massive dust clouds
from Asia and North Africa toward North
America. Within a few days these clouds can
cross the Atlantic and Pacific Oceans, transport-
ing pollutants and microorganisms along with the
dust. Images such as this provide visual confir-
mation of atmospheric pathways between conti-
nents.
APR 11 vi Birtn Ptob*
Figure 1-7. False color image of the aerosol abundance in
the atmosphere obtained by NASA's Earth Probe TOMS
satellite. The aerosol index is a measure of the absorp-
tion of solar ultraviolet radiation by airborne particles.
Source: National Aeronautics and Space Administration
1-7
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Genesis of the Global POPs Treaty
Beyond physical transport on dust and sediment
particles, empirical data and the physical proper-
ties of a number of POPs indicate that these
substances may be preferentially accumulating in
cold polar climates through global distillation.
Certain POPs that exhibit a particular range of
physical properties—often characterized as
semivolatile—may evaporate in tropical and
temperate climates and condense in cold regions.
In a more absolute sense, and independent of
whether transport occurs via volatilization or
physical transport on particles or in water, once a
substance reaches the frozen polar regions, nor-
mal physical degradation time scales and half-
lives lose their relevance.
It is the combination of persistence, bioaccumu-
lation, toxicity, and long-range environmental
transport that makes POPs problematic. All 12
prioritized POPs or their breakdown products
rank high to extreme on measurements of these
parameters. Low values on any of the param-
eters will substantially reduce transboundary con-
cern, although local problems may remain. The
parameters also serve as the basis for screening
levels in virtually all international POPs agree-
ments, including the Stockholm Convention. In
screening for potential POPs using these param-
eters, the limitations of such an approach are
recognized through an emphasis on flexibility and
expert judgment in determining the level of risk
produced by a substance and what action is
warranted.
The story of POPs begins with the growth of the
organic chemical industry in the early 20th cen-
tury, and with foresight will end as we enter the
21st century. DDT was first synthesized in
1874, but its insecticidal properties remained
unknown until reported in 1939 by the Swiss
chemist Paul Hermann Muller. A skin rash called
chloracne was reported by Karl Herxheimer
(Herxheimer, 1899) to be afflicting German
workers in the chlorinated organic chemical in-
dustry in 1899, although the causal agent, di-
oxin, remained elusive for many decades (Figures
1-8, 1-9). PCBs were first produced commer-
cially in 1929, peaked in 1970, and were
banned from production in the United States by
1979. Dieldrin and aldrin were first synthesized
as pesticides in the United States in the late
1940s. They were named for Drs. Otto Diels
and Kurt Alder, who developed the Diels-Alder
process for diene (2 double bonds between car-
bon atoms) synthesis in 1928. With World War II
and reconstruction came a broad public aware-
ness of the potential marvels of chemicals such
as DDT for disease vector control, exemplified
by international efforts seeking to eradicate dis-
eases such as malaria. At the same time, newly
developed organochlorine pesticides and herbi-
cides were rapidly filling the needs of the grow-
ing agrochemical industry.
But as the use of halogenated, particularly chlori-
nated, organic chemicals rose in agricultural and
industrial sectors, so did warnings about potential
adverse consequences to human health and the
environment. In 1962, a sentinel event occurred
with the publication of Rachel Carson's Silent
Spring. Through this book and the surrounding
media attention, the public first became aware
of a downside to the proliferation of chemicals,
with warnings of spring devoid of songbirds.
Chemicals intended for insect control were being
found to accumulate in the food chain, causing
eggshell thinning, chick mortality, and other
Figure 1-8. Agent Orange barrels during the Vietnam
War, contaminated with dioxin.
Source: USAF
1-8
-------
Genesis of the Global POPs Treaty
Figure 1-9. Aerial spraying Agent Orange defoliant,
Vietnam.
Source: USAF
unforeseen damage. Adding halogen atoms
(fluorine, chlorine, bromine, iodine) had been
used to make organic molecules more resistant
to degradation. The persistence of these organo-
chlorine structures, and the propensity of some
to bioaccumulate, were central to the problems
being experienced. Increased persistence meant
that mistakes made with POPs lingered, such as
the prolonged ecological damage caused by
chemical spills. Because persistent organochlo-
rine pesticides were nonselective in their toxicity
to insects, they caused prolonged killing of both
pest insects and beneficial creatures that preyed
on these pests. Prolonged, indiscriminate lethal-
ity also precipitated secondary pest outbreaks,
where insect species not generally considered a
problem rose in prominence through disruption
of ecological processes.
Beyond these agricultural and ecological concerns
lay the human dimension of pesticide and PCB
residues in the food supply. Data from tests in
rodent species showed that many of these sub-
stances were possible or probable human car-
cinogens. Passage of the Delaney Clause in the
1958 Food Additives Amendment to the Food,
Drug, and Cosmetic Act (FDCA) mandated that
no carcinogens be added to the food supply—a
zero-risk policy. Legal and regulatory decisions
to operationalize this requirement stimulated
efforts to quantify cancer risk estimates and led
to the concept of a de minimus concentration, a
level below which risks were considered too small
to warrant legal attention. The organochlorine
POPs, both industrial and chemical, were central
to many of these debates. Compounding this
pressure for risk quantification was increasing
public concern about contaminated industrial
sites and toxic chemical pollution. In response, a
combination of legislative, regulatory, legal, and
voluntary actions ultimately facilitated the devel-
opment and use of newer pesticides and indus-
trial alternatives in the United States, replacing
the problematic organochlorines.
But while uses and levels in the environment,
food, and tissue were stabilizing or declining in
the lower 48 United States, reports began ap-
pearing in the scientific literature of increasing
levels in what had been thought pristine, uncon-
taminated environments. In particular, increas-
ing haze and contamination in the Arctic became
a priority concern of northern countries. In
1991, Environment Ministers from the Arctic rim
countries (Canada, Denmark/Greenland, Finland,
Iceland, Norway, Sweden, Russia, United States;
Figure 1-10) established the Arctic Monitoring
and Assessment Programme (AMAP;
LULUtu.amap.no) to measure the levels and assess
the effects of man-made pollutants in the Arctic
environment. Priority attention was directed
toward POPs, together with heavy metals and
radioactivity. The AMAP efforts, consolidating
and supported by domestic programs in Arctic
countries (e.g., Canadian Northern Contaminants
Program, Jensen et al., 1997), helped focus
attention on the long-range transboundary move-
ment of POPs. Long-range environmental trans-
port concerns were reinforced with the finding of
elevated POPs levels in wildlife on remote mid-
Pacific islands (Jones et al., 1996).
Transboundary pollution issues, and the opportu-
nity to address them, also gained greater promi-
nence with the easing of Cold War tensions. In
1979, member countries of the United Nations
Economic Commission for Europe (UNECE) had
signed the Convention on Long-Range
Transboundary Air Pollution (LRTAP), initially
directed at controlling transboundary sulfur and
acid rain pollution. Beyond its name, the
7-9
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Genesis of the Global POPs Treaty
Figure 1-10. Arctic topography and bathymetry.
Source: AMAP.
UNECE region includes Canada, the United
States, Western Europe, Eastern Europe and
Newly Independent States, and Russia, circling
the upper Northern Hemisphere. With a grow-
ing understanding of the transboundary nature of
POPs pollution, the UNECE-LRTAP agreement
offered an ideal vehicle to advance POPs control
efforts. In 1992, background work commenced
on parallel UNECE-LRTAP protocols to address
POPs and heavy metals. Criteria for the priority
scoring and selection of POPs were developed,
along with a process for reviewing individual
chemicals for potential action by the LRTAP
parties (AEA, 1995, 1996). Negotiations on a
formal POPs protocol began in 1994 and were
completed in 1998 (www.unece.org/enc/lrtap),
following which the protocol was signed by the
United States.
UNEP Global POPs Negotiations
The written record of the global POPs negotia-
tion traces to Agenda 21 of the Rio Declaration
on Environment and Development in June 1992
(United Nations, 1993). The foundation and
priority for POPs action were enunciated in Ob-
jective 17, Protection of the Oceans, and Objec-
tive 19, Environmentally Sound Management of
Toxic Chemicals. Under Protection of the Ma-
rine Environment, section 17:18 stated:
Many of the polluting substances originating
from land-based sources are of particular
concern to the marine environment since
they exhibit at the same time toxicity, per-
sistence and bioaccumulation in the food
chain. There is currently no global scheme
to address marine pollution from land-based
sources.
Similar concerns were echoed in section 19:44,
Establishment of Risk Reduction Programmes,
where Agenda 21 called for
the phasing out or banning of chemicals that
pose unreasonable or otherwise unmanage-
able risks to human health and the environ-
ment and of those that are toxic, persistent
and bioaccumulative and whose use cannot
be adequately controlled.
In May 1995, these concerns about POPs served
as the basis for Decision 18/32 of the United
Nations Environment Programme Governing
Council (UNEP-GC), which commenced a techni-
cal review process to document POPs risks and
response strategies. The initial list of POPs
consisted of the 12 under discussion at that time
by the UNECE-LRTAP Parties. The following
principal events trace the chronology and devel-
oping consensus for international action on
POPs:
November 1995: Washington Declaration
on Protection of the Marine Environment
from Land-Based Activities (http://
www.unep.org/unep/gpa/pol2bl2.htm).
December 1995: Inter-Organization
Programme for the Sound Management of
Chemicals (IOMC) Persistent Organic Pollut-
ants Assessment Report (Ritter et al., 1995).
7-70
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Genesis of the Global POPs Treaty
March 1996: Intergovernmental Forum on
Chemical Safety (IFCS), second meeting of
the Inter-Sessional Group (ISG-2), Canberra,
Australia (ISG/96.5a).
June 1996: Intergovernmental Forum on
Chemical Safety (IFCS) Experts Meeting on
POPs: Persistent Organic Pollutants: Consid-
erations for Global Action. Manila, Philip-
pines (IFCS/EXP.POPs./Report.l, 20 June
1996).
February 1997: UNEP Governing Council,
Decision 19/13C. International action to
protect human health and the environment
through measures that will reduce and/or
eliminate emissions and discharges of per-
sistent organic pollutants, including the
development of an international legally bind-
ing instrument (http://irptc.unep.ch/pops/}.
Decision 19/13C of the UNEP Governing Coun-
cil in February 1997 constituted the formal
agreement to create an intergovernmental nego-
tiating committee (INC) to develop the text for a
binding global POPs convention. Negotiations
were to commence in 1998 and conclude by
2000. Decision 19/13C provided a detailed
mandate to guide the negotiations, centered
around the UNEP-GC decision that
immediate international action should be
initiated to protect human health and the
environment through measures which will
reduce and/or eliminate ... the emissions
and discharges of the twelve persistent
organic pollutants specified in Governing
Council decision 18/32 and, where appro-
priate, eliminate production and subse-
quently the remaining use of those persis-
tent organic pollutants that are intentionally
produced.
Negotiations began in Montreal, Canada, in June
1998, following a series of awareness-building
workshops in developing countries to inform
governments on scientific issues concerning
POPs. Subsequent negotiating sessions were
held in Nairobi (January 1999), Geneva (Septem-
ber 1999), and Bonn (March 2000), culminating
in the agreement reached in Johannesburg (De-
cember 2000) (Figure 1-11). Technical consider-
ations on criteria for the addition of substances
were covered during two criteria expert group
(CEG) meetings in Bangkok (October 1998) and
Vienna (June 1999). Signing of the treaty by the
United States and 90 other nations was held in
Stockholm, Sweden, in May 2001, hence the
designation Stockholm Convention (Table 1-1).
The treaty is currently open for signature and
ratification by countries. Ratification by indi-
vidual countries confirms their signature and
makes them a party to the treaty, following
review and consent through the domestic politi-
cal, legal, and legislative process. The Conven-
tion will enter into force after it has been ratified
by 50 nations. Entry into force applies only to
parties that have ratified the Convention.
Before detailing POPs case studies in the United
States and links to long-range environmental
transport, it is worthwhile clarifying some as-
sumptions and misconceptions that often occur
when evaluating POPs. In particular, an under-
Figure 1-11. Concluding the POPs negotiations,
Johannesburg, South Africa, December 2000.
Source: International Institute for Sustainable Development.
7-77
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Genesis of the Global POPs Treaty
Table 1-1. Elements of the Stockholm Convention
Objective: "... to protect human health and the environment from persistent organic
(Article 1) pollutants."
Article 2 Definitions
Article 3 Measures to reduce or eliminate releases from intentional production and use
Article 4 Register of specific exemptions
Article 5 Measures to reduce or eliminate releases from unintentional production
Article 6 Measures to reduce or eliminate releases from stockpiles and wastes
Article 7 Implementation plans
Article 8 Listing of chemicals in Annexes A, B, and C
Article 9 Information exchange
Article 10 Public information, awareness, and education
Article 11 Research, development, and monitoring
Article 12 Technical assistance
Article 13 Financial resources and mechanisms
Articles 14-30 Interim financial arrangements; reporting; effectiveness evaluation; noncompli-
ance; settlement of disputes; conference of the parties; secretariat; amend-
ments to the Convention; adoption and amendment of annexes; right to vote;
signature; ratification, acceptance, approval or accession; entry into force;
reservations; withdrawal; depository; authentic texts
Annex A Chemicals listed for elimination
Annex B Chemicals listed for production and use restrictions
Annex C Unintentionally produced POPs, source categories, and control measures
Annex D Information requirements and screening criteria
Annex E Information requirements for the risk profile
Annex F Information on socio-economic considerations
standing of POPs problems requires a movement
beyond standard considerations of timing,
causes, and effects of pollution. The evaluation
must also consider the peculiar impacts of ex-
tremes of persistence, bioaccumulation, toxicity,
and long-range environmental transport.
• POPs pesticides are still being produced:
From the United States' perspective, the
listed POPs pesticides (all organochlorines) are
generally considered "dinosaur" chemicals from
a bygone era whose production has ceased.
They have been superseded by more carefully
tailored, selective, and less persistent and
bioaccumulative alternatives. These alterna-
tives, although in some cases potentially more
acutely toxic to applicators (e.g., some orga-
nophosphates), are usually less prone to induc-
ing pest resistance, lead to fewer secondary
pest infestations, and result in less food con-
tamination. But, as the UNEP POPs negotia-
tions demonstrated, on a world scale POPs
are not gone, with many still being produced
and used, especially in developing countries.
A number of factors, principally economic,
contribute to this continuing use. Organochlo-
rine pesticides are often cheap, easy to pro-
duce, and off-patent. Their persistence con-
tributes to their perceived economic benefit,
because one application of chlordane
termiticide or DDT insecticide can last much
longer than modern alternatives. Finally,
7-72
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Genesis of the Global POPs Treaty
some organochlorine pesticides are also per-
ceived to exhibit lower acute mammalian
toxicity, and are applied in developing coun-
tries with less emphasis on training and ex-
pensive protective equipment for applicators.
All POPs are not the same: Although the 12
priority substances exhibit similar high to
extreme measures for persistence, bioaccum-
ulation, toxicity, and long-range transport,
there is large variability in other physical prop-
erties. Values for volatility, solubility, and
Henry's Law constant (water-air partition
coefficient, important for air transport model-
ing) vary by up to 5 orders of magnitude be-
tween substances (100,000-fold). A conse-
quence is that not all POPs are expected to
exhibit the same propensity for global distilla-
tion (Wania and Mackay, 1996).
POPs concentrations are higher near their
sites of release: The focus on a global POPs
convention and transboundary pollution should
not obscure the reality that the highest POPs
concentrations are generally found close to the
sites of release. Problems in the United
States are generally homegrown. This prox-
imity does not negate the importance of inter-
national action, but emphasizes the need for
care in determining appropriate actions. For
example, POPs levels in marine mammals in
the lower 48 United States are often much
higher than those found in Alaska. However,
marine mammals constitute a dietary staple in
the subsistence lifestyle of many Alaska Na-
tives. Their health and cultural well-being are
threatened by substances from beyond U.S.
borders that they neither used nor derived
benefit from and yet now contaminate their
environment.
Low concentrations in remote locations do
not preclude a substance being a POP:
Concentrations in remote locations reflect a
combination of POPs parameters, emission
levels, and accumulation time. For a sub-
stance such as endrin, an isomer of dieldrin,
the relatively low concentrations found at long
range are principally a result of the lower
historic use levels in temperate climates.
Endrin has POPs parameters similar to dield-
rin, so any increased use of endrin as a substi-
tute for dieldrin would be expected to lead to
similar long-range risks.
Contemporaneous appraisals of pollution
cause and effect are insufficient: Often when
we think of environmental pollution we equate
contemporary emissions with contemporary
concentrations and effects on those exposed.
These assumptions do not hold for POPs and
must be modified by a more detailed exami-
nation of the science underlying POPs
properties.
- Cumulative dose measures are prefer-
able. The long environmental and biologi-
cal half-lives of POPs result in a cumulative
dose, where current tissue concentrations
are a modified sum of past exposures. For
persistent chemicals, tissue-concentration
metrics that integrate dose, rather than
daily dose measures, should be used to
assess toxic risk (unless daily dose is inter-
preted consistent with half-life consider-
ations).
- Concentrations will build up for decades.
As a result of cumulative exposure, it is
incorrect to assume that if a pesticide has
been used for several years at a consistent
level, then the concentrations now in the
environment represent the peak or worst-
case scenario. Persistence values for many
of the POPs may be of such duration that,
at a steady use rate, environmental con-
centrations could continue increasing for
more than a century. Thus, actions to
assess impacts and reduce use must be
guided by predicted concentrations at the
end of the accumulation cycle.
- Momentum. Solving POPs pollution prob-
lems takes time. These substances persist
and recycle in the environment, potentially
moving long distances. For those environ-
ments and peoples at the receiving end of
this migration—e.g., sinks such as the
1-13
-------
Genesis of the Global POPs Treaty
Arctic—cessation of release at the source
may not end POPs accumulation, which
will take considerably longer.
The world of the future will be different.
We must look beyond the world of the
present and to the future when evaluating
potential long-term benefits of the
Stockholm Convention. As illustrated in
Chapter 8, the world of the future will
have higher population levels (Figure 1-12),
increased industrial activity, and chemical
development and production concentrated
in what are now developing countries. A
central consideration should be the future
POPs emissions potential and impact on
the United States from these countries, if
unconstrained by an implemented
Stockholm Convention.
A toxic legacy of POPs at birth. Growing
embryos and newborns of all species un-
dergo extremely complex developmental
changes to reach their peak performance
potential (Figure 1-13), necessary to sur-
vive in a competitive and often dangerous
world. This period of development is pro-
tected by biological defenses developed
over eons of evolution, from maternal
detoxification and placental barriers to the
rich nutrients and proteins in mother's
milk. POPs thwart these barriers through
their resistance to metabolism, passage
across biological membranes facilitated by
their relatively low molecular weight, and
high lipid solubility leading to concentration
in body fats. The high energy demands of
growth and development are also best
satisfied through high-fat-content milk, the
ideal POPs dosing mechanism. Indeed,
through lactation and nursing her young, a
female mammal can purge herself of POPs
by transfering the lipophilic (i.e., fat-
soluble) substances to her offspring. Toxic
effects during sensitive periods of develop-
ment have not been adequately studied.
Regional Total Population
4500
4000
I" a*? ':IF'"PC
I'sfelOl
• Mideofl
-ROW
United Sites
Wed Bin ft
FSU = Former Soviet Union
ROW = Rest of World
,'! I'll I
Figure 1-12. World population growth projections.
1-14
-------
Genesis of the Global POPs Treaty
Figure 1-13. Normal four-month human fetus, in utero ultrasound image.
Photo: B. Rodan
All too often, scientists and regulatory
agencies must account for risks to the
newborn by relying on data derived from
adult animals or limited reproductive and
physical development studies in rodents.
AEA. 1995. Prioritisation Criteria for the Selection of
Persistent Organic Pollutants — A Comparison of Selec-
tion Schemes. AEA Technology, National Environmental
Technology Center, UK.
AEA. 1996. A Concise Review of the Development by
the PWG/POPs of the Criteria and Procedure Recom-
mended for Priority Substance Identification. AEA Tech-
nology, National Environmental Technology Center, UK.
Beyer WN, Heinz GH, Redmon-Norwood AW, eds.
1996. Environmental Contaminants in Wildlife:
Interpreting Tissue Concentrations. SETAC Special
Publications Series. Boca Raton, FL: CRC Press, Lewis
Publishers.
Carson R. 1962. Silent Spring. Boston: Houghton
Mifflin.
Guillette LJ Jr, Brock JW, Rooney AA, Woodward AR.
1999. Serum concentrations of various environmental
contaminants and their relationship to sex steroid concen-
trations and phallus size in juvenile American alligators.
Arch Environ Contam Toxicol 36(4): 447-455.
Herxheimer K. 1899. Chloracne. Munchenere Med
Wochenschr 46:278.
Jensen J, Adare K, Shearer R. 1997. Canadian Arctic
Contaminants Assessment Report. Department of Indian
Affairs and Northern Development. Ottawa, Canada.
Jones PD, Hannah DJ, Buckland SJ, Day PJ, Leathern
SV, Porter LJ, Auman HJ, Sanderson JT, Summer C,
Ludwig JP, Colborn TL, Giesy JP 1996. Persistent
synthetic chlorinated hydrocarbons in albatross tissue
samples from Midway Atoll. Environ Toxicol Chem
15(10): 1793-1800.
7-75
-------
Genesis of the Global POPs Treaty
Klecka G, Boethling B, Franklin J, Grady L, Graham D,
Howard PH, Kannan K, Larson RJ, Mackay D, Muir D,
van de Meent D, eds. 2000. Evaluation of Persistence
and Long-Range Transport of Organic Chemicals in the
Environment. Pensacola, FL: SETAC Press.
Ritter L, Solomon KR, Forget J, Stemeroff M, O'Leary
C. 1995. An Assessment Report on DDT-Aldrin-Dield-
rin-Endrin-Chlordane-Heptachlor-Hexachlorobenzene-
Mirex-Toxaphene-Polychlorinated Biphenyls-Dioxins and
Furans. For the International Programme on Chemical
Safety (IPCS) within the framework of the Inter-Organiza-
tion Programme for the Sound Management of Chemi-
cals (IOMC): http://irptc.unep.ch/pops/indxhtms/
asses0.html.
United Nations. 1993. Agenda 21: Programme of
Action for Sustainable Development. Rio Declaration on
Environment and Development, 1992. Final Text of
Agreements Negotiated by Governments at the United
Nations Conference on Environment and Development
(UNCED), 3-14 June, 1992, Rio de Janeiro, Brazil.
United Nations Department of Public Information, New
York.
U.S. Environmental Protection Agency. 1995. Great
Lakes Water Quality Initiative Technical Support Docu-
ment for the Procedure to Determine Bioaccumulation
Factors. Office of Water. EPA/820/B-95-005.
U.S. Environmental Protection Agency. 1999. Fact
Sheet. Polychlorinated Biphenyls (PCBs) Update: Impact
on Fish Advisories. Office of Water. EPA-823-F-99-019.
Wania F, Mackay D. 1996. Tracking the distribution of
persistent organic pollutants. Environ Sci Technol
30:390A-396A.
7-76
-------
T.«
he scientific literature on persistent organic
pollutants (POPs) is voluminous, complex, and
intriguing. These are some of the most researched
chemicals in existence, yet that research has served
to stimulate even more investigation, down to their
effects on the intricacies of DNA replication control
and cellular differentiation. With this as the back-
drop, this chapter seeks to demystify what these
chemicals are, why they were developed, what they
do, what was discovered about their toxic effects,
and why they are the focus of global action.
Twelve substances or substance groups are ini-
tially included under the Stockholm Convention on
Persistent Organic Pollutants (Table 2-1). These
POPs all exhibit the properties of prolonged envi-
ronmental persistence, bioaccumulation, toxicity,
and the potential for long-range environmental
transport (see Chapter 9). They can be divided
into three general categories of pesticides, indus-
trial chemicals, and unintentional byproducts. Sev-
eral of the POPs occur under more than one cat-
egory, such as hexachlorobenzene, which has been
used as a fungicide and an industrial feedstock and
product, and is also emitted as an unintentional
byproduct from incineration and the manufacture
of other pesticides. Several of the substances
represent groups of chemicals with similar struc-
tures and properties, namely the congener families
of polychlorinated dioxins and furans, polychlori-
nated biphenyls (PCBs), and the mixed chlorinated
camphenes (toxaphene).
This chapter provides a narrative introduction to
each of the POPs. To avoid repetition, narratives
are combined for similar chemical groups, such as
the cyclodiene pesticides and polychlorinated diox-
ins and furans. More detailed information can be
found from a variety of federal databases and texts,
examples of which are included in an appendix at
the end of this chapter. Each chemical descrip-
tion includes a table of technical and numerical
data on the POP. These tabular data categories,
an explanation of their relevance to understand-
ing the chemical's potential environmental im-
pact, and the information sources (unless other-
wise specified in the table) are as follows:
•*• Chemical information and structure (Klecka et
al., 2000; a subset of chemical structure draw-
ings is used with permission of SETAC). Rep-
resentative examples are provided for sub-
stance groups where physical, chemical, and
biological properties vary between members of
the substance group.
-$• Environmental persistence estimates, recogniz-
ing the wide variability of these parameters in
different physical environments (i.e., light,
temperature, moisture, bacteria, etc.) (Klecka
et al., 2000).
i?= Chemical properties important for evaluating
the potential for long-range environmental
transport, such as the vapor pressure and the
air-water partition coefficient or Henry's Law
constant, which measures the pressure in air
over the concentration in water at a constant
temperature (Ritter et al., 1995). A high air-
water partition coefficient indicates that move-
ment of the chemical is facilitated to the vapor
phase, increasing the likelihood that it can
undergo long-range transport in the atmo-
sphere.
•*• Bioaccumulation, through both the octanol-
water partition coefficient (equilibrium concentra-
tion in an n-octanol solution over the concentra-
tion in contiguous water; Klecka et al., 2000)
and measured estimates from fish species
(summarized in Rodan et al., 1999; whole
body lipid-adjusted to 5%).
2-1
-------
Profiles of the POPs
POP
Aldrin
Chlordane
Dichlorodiphenyl-
trichloroethane
(DDT)
Dieldrin
Endrin
Heptachlor
Hexachlorobenzene
(HCB)
Mirex
Polychlorinated
biphenyls (PCBs)
Polychlorinated
dibenzo-p-dioxins
(dioxins)
Polychlorinated
dibenzofurans
Jfi£ans)___
Toxaphene
Table 2-1. The 12 POPs under the Stockholm Convention and their current U.S. status
2001 Status for Production and/or Emissions under TSCA,8 FIFRA,b CAA,C and CWAde
No registrations, most uses canceled in 1969, all uses by 1987
No production, import, or export
All tolerances on food crops revoked in 1986
Priority toxic pollutant under the CWA
No registrations, most uses canceled in 1978, all uses by 1988
No production (stopped in 1997), import, or export
All tolerances on food revoked in 1986
Regulated as a hazardous air pollutant (CAA)
Priority toxic pollutant under the CWA
No registrations, most uses canceled in 1972, all uses by 1989
No production, import, or export
All tolerances on food and feed crops revoked in 1986
The metabolite DDE regulated as a hazardous air pollutant (CAA)
D>DT,jyyj^^
No registrations, most uses canceled in 1969, all uses by 1987
No production, import, or export
All tolerances on food crops revoked in 1986
Priority toxic pollutant under the CWA
No registrations, most uses canceled in 1979, all uses by 1991
No production, import, or export
Priority toxic pollutant under the CWA
Most uses canceled by 1978, registrant voluntarily canceled use to control fire
ants in underground cable boxes in early 2000
No production (stopped in 1997), import, or export
All tolerances on food crops revoked in 1989
Regulated as a hazardous air pollutant (CAA)
Heptachlor and heptachlor epoxide priority toxic pollutants under the CWA
No registrations as a pesticide, all uses canceled by 1985
No production, import, or export as a pesticide
Production and use as a closed-system intermediate consistent with the Stockholm Convention
Regulated as a hazardous air pollutant (CAA)
Priority toxic pollutant under the CWA
No registrations, all uses canceled by 1977
No production, import, or export
Recommended nonpriority toxic water pollutant (U.S. EPA, 1999)
No manufacture and new use prohibited in 1978 (TSCA)
Regulated as a hazardous air pollutant (CAA)
Priority toxic pollutant under the CWA
As a contaminant in production, regulated under TSCA and FIFRA
Hazardous air pollutant and emission standards regulated under the CAA
jy^^-TCD^
As a contaminant in production, regulated under TSCA and FIFRA
Hazardous air pollutant and emission standards regulated under the CAA
No registrations, most uses canceled in 1982, all uses by 1990
No production, import, or export
All tolerances on food crops revoked in 1993
Regulated as a hazardous air pollutant (CAA)
Priority toxic pollutant under the CWA
" Toxic Substances Control Act
Federal Insecticide, Fungicide, and Rodenticide Act
0 Clean Air Act
d Clean Water Act
" Effluent limits and standards for all POPs are authorized under the CWA.
' National Recommended Water Quality Criteria-Correction. US-EPA 822-Z-99-001. Office of Water.
2-2
-------
Profiles of the POPs
Acute toxicity in rats, estimated as the acute
dose that would kill half the experimental rats
(lethal dose 50%; LD50), noting that within
species there is a spectrum of individual resis-
tance to toxic effects, and that between-spe-
cies LD50 values can vary to a large degree
(Meister, 2000).
Chronic toxicity reference dose (RfD) in the
United States, which is an estimate (with uncer-
tainty spanning perhaps an order of magnitude)
of a daily exposure to the human population
(including sensitive subgroups) that is likely to be
without an appreciable risk of deleterious effects
during a lifetime. The RfD is based on experi-
mental or epidemiologically determined doses at
which there is no statistically or biologically
significant indication of toxic effects. RfDs in-
clude uncertainty factors to account for animal-
to-human interspecies differences, variability
between humans, and database deficiencies
(www.epa.gov/IRIS).
History of production and use in the United
States, providing a brief summary of historical
manufacturing data, years during which these
activities occurred, and when they were curtailed
and ultimately ceased (UNEP, 2000).
International production and use, summarizing
data collected by the United Nations Environ-
ment Programme (UNEP) during the POPs
negotiation and from national requests for
chemical-specific use exemptions under the
Stockholm Convention (UNEP, 2000).
The nine pesticide POPs were introduced into
commercial use after World War II and dramatically
changed modern pest control. These compounds
were effective against a wide range of pests, often
for extended periods of time. Ironically, the chemi-
cal property of long environmental persistence that
enhanced the pesticides' efficacies also increased
their environmental destructiveness. Repeated
applications of the pesticide POPs (Figure 2-1) led
to widespread contamination, impacts on non-
target species, and residues in foods.
Figure 2-1. Aerial spraying of pesticides on crops.
Photo: U.S. EPA
Aldrin, dieldrin, endrin, chlordane, heptachlor,
and mirex are all cyclodiene organochlorine in-
secticides. They are highly persistent com-
pounds, exhibiting especially high resistance to
degradation in soil. Aldrin, dieldrin, and particu-
larly endrin exhibit high acute mammalian toxic-
ity (oral LD50s between 7 and 90 mg/kg); chlor-
dane, heptachlor, and mirex are moderately
acutely toxic (oral LD50s between 100 and 400
mg/kg) (Meister, 2000). Due to the persistence
of these insecticides, surface application on food
crops proved problematic because residues re-
mained on produce after harvest. The cyclo-
dienes were, however, widely used as soil insecti-
cides in the United States, particularly against
termites and soil-dwelling insects that attack the
roots of crop plants. Although the agricultural
uses of the cyclodienes were cancelled by the
EPA during the 1970s, they continued to be used
under restricted conditions as termiticides well
into the 1980s (Ware, 1989).
Aldrin, dieldrin, and endrin are extremely similar
chemically, the latter two being stereoisomers of
each other (Tables 2-2, 2-3, and 2-4). Aldrin is
rapidly transformed into dieldrin both in air and in
soil (Glotfelty, 1978; Gannon and Bigger, 1958).
Endrin was used initially as a general insecticide,
particularly on nonfood crops such as cotton and
tobacco. It also served as an avicide (bird-killing
agent) and rodenticide, exploiting its high toxicity
2-3
-------
Profiles of the POPs
Chemical
information
Persistence
Properties related to
environmental transport
Table 2-2. Aldrin
CAS number: 309-00-2
Molecular formula: C12H8C16
Half-lives: < 0.4 days (air)
-1.1-3.4 years (water)
-1.1-3.4 years (soil) _
Henry's law constant: 4.96 x 1(H atm-m3/mol at 25 C
Vapor pressure: 2.31 x 10~5 mm Hg at 20°C
Solubility in water: 17-180 ug/L at 25°C
, (octanol-water partition coefficient)
BAF/BCF - 6100
Bioaccumulation
Acute toxicity
106
Oral LD = 38-67 mgAg
_Chrc£ncjtoxicity
US production
history
US use history
Current (2001)
international production
andjeportechase
______
bATSDR, 1993a.
mg/kg/day (UF = 1000)
Years produced3: 1948-1974
Peak usage in 1966b: 8,600 tonnes (19 million Ibs)
No present production, import, or export in USA
- Insecticide on cotton, citrus, and corn crops
- Termiticide
^^ _
- No known current producers
- Reported use as an ectoparasiticide in one country
to vertebrates. Aldrin and dieldrin, which were
inexpensive to manufacture, were produced in
large quantities in the United States during the
1960s and used most frequently as insecticides to
control soil pests affecting corn and citrus crops, as
well as termites in buildings and other structures.
The long persistence of dieldrin (whether from
initial dieldrin formulations or from aldrin formula-
tions) and its acute toxicity to nontarget wildlife
led to environmental concerns, particularly after
numerous mass bird deaths were associated with
the use of dieldrin as a seed treatment (Beyer et
al., 1996). However, long before regulatory ac-
tions to restrict or cancel these insecticides were
instigated, technical problems had emerged be-
cause of their broad-spectrum toxicity and long
persistence. The production and uses of aldrin,
dieldrin, and endrin declined significantly by the
mid-1970s in the United States, due in large part
to the development of resistance in target pests
(Ware, 1989) and problems with secondary pest
upsets caused by the elimination of natural preda-
tors (DeBach and Rosen, 1991). The develop-
ment of other pesticides (organophosphates,
carbamates, synthetic pyrethroids and, more
recently, insect growth regulators) that were con-
sidered more effective and less environmentally
destructive also reduced demand for the cyclodi-
ene insecticides (ATSDR, 1993a).
Aldrin was also produced and widely used overseas,
particularly for the control of cotton pests and
termites, until human health and environmental
concerns led to bans in many countries (Pearce,
1997). Dieldrin was initially used for indoor house
spraying to control mosquitoes that carry malaria,
but it is no longer used or recommended by the
World Health Organization (WHO) because of its
high mammalian toxicity and resistance problems
among many target mosquitoes (Rozendaal, 1997;
Shidrawi, 1990). Dieldrin was also donated to
African countries until the late 1980s to control
plagues of migratory locusts, creating numerous
2-4
-------
Profiles of the POPs
Chemical
information
Persistence
Properties related "to
environmental transport
Bioaccumulation
Acute toxicity
Chronic toxicity
US production
history
US use history
Table 2-3. Dieldrin
CAS number: 60-57-1
Molecular formula:
Molecular_weight: 380.92
____ -,____
C12H8C160
-1.1-3.4 years (water)
-1.1-3.4 years (soil) __ _ _ _ _
Henry's Taw constant: 5.8 x i.0"~5 atm-m3/mol at 25°C
Vapor pressure: 1.78 x 10~7 mm Hg at 20°C
Solubility in water: 140 ug/L at 20°C
KOW (octanol-water partition coefficient) - 1052
BAF/BCF -920,000
Oral LD50 = 37-87 mg/kg
Deraial_LD5!L=_60:90 mg/kg __
Reference dose (RfD) = 5 x lO"5 mg/kg/day (UF = 100)
Years produced3: 1948 - 1974
Peak US usage in 1966b: 455 tonnes (1 million Ibs)
No present production, import, or export in USA
- Insecticide control on cotton, citrus, and corn crops
- Termiticide
All uses canceled by 1987
Current international
production and use
- No known current producers
- Insecticide used until 1980s for control of plague locusts. No current uses
except for agricultural operations in one country (for 2 years to exhaust existing
bATSDR, 1993a.
stockpiles of obsolete chemicals that remain an
environmental hazard in many countries (FAO,
1998) (Figure 2-2). Newer pesticides, including
phenylpyrazole compounds, are now available
Figure 2-2. Obsolete drums of dieldrin, previously used
for locust control, Morocco.
Photo: Janice Jensen
for locust control, although the economic costs
and environmental damage associated with these
large-scale pesticide applications suggest that
information-based integrated pest management
approaches using less total pesticide are more
appropriate locust control strategies (Showier and
Potter, 1991).
Chlordane, heptachlor, and mirex were used
extensively in the United States in the 1950s
and 1960s for the control of soil insects in agri-
cultural crops, and for termites and other struc-
tural pests in buildings (Figure 2-3). Chlordane
and heptachlor have very similar chemical struc-
tures (Tables 2-5 and 2-6). Chlordane was
manufactured and used as a complex mixture of
related compounds (cis- and trans-chlordane,
heptachlor, nonachlor, plus many lesser com-
pounds), often referred to as technical chlordane
(Sovocool et al., 1977). It was often applied
2-5
-------
Profiles of the POPs
Chemical
information
Persistence
Table 2-4. Endrin
CAS number: 72-20-8
Molecular formula: C12H8C16O
_
Half-lives"3":" -2.2 dayslair)
-1.0-4.1 years (water)
-4-14 years (soil)
Henry's law constant5: 6.36 x 10"6 atm-m3/mol at 25 C
Vapor pressure: 7 x 10~7 mm Hg at 25°C
Solubility in water: 220-260 ug/L at 25°C
Properties related to
environmental transport
Bioaccumulation
Acute toxicity
KOT (octanol-water partition coefficient)
BAF/BCF - 7,000__
"Oral LD~="7~15 mg/kg"
Dermal LD . = 15 mg/kg (female)
1052
Chronic toxicity
US use history
Reference dose (RfD) = 3 x 10~4 mgAg/day (UF = 100)
luction Years produced0: 1951-1986
history Peak US usage in 1962d: Estimated 2270-4545 tonnes (5 to 10 million Ibs)
No present production, import, or export in USA
- Insecticide on cotton crops
- Rodenticide in orchards
- All uses canceled by 1991
Current international
production_and_use______
,——,,——————.,
Soil: Menzie, 1972; HSDB
bHSDB, 2002.
CATSDR, 1996a.
dIARC, 1974.
- No known current producers
- No current use reported
____________
, 1997.
directly to soil to create a chemical barrier
against subterranean termites, frequently remain-
ing effective for 25 years or more in temperate
areas (Grace et al., 1993). Heptachlor was
applied both directly to soil and seeds for agricul-
Figure 2-3. Subterranean worker termites, a target of
chlordane and some other POPs pesticides.
Photo: Clemson University Cooperative Extension Service - USDA joint
project
tural uses and to wood for termite protection
(ATSDR, 1993b). Heptachlor is converted in the
environment to heptachlor epoxide, prolonging
its persistence and toxicity. The last registered
use for heptachlor in the United States, now
cancelled, was as an insecticide in small contain-
ers placed in cable boxes in the southeast to
prevent nest building by fire ants in electrical
equipment. Registered chlordane uses in the
United States were cancelled by 1988 in re-
sponse to evidence of human exposure through
accumulation of chlordane in fat, and human
cancer risks based on animal bioassay results.
Both chlordane and heptachlor are still used in
several African, Asian, and Eastern European
countries for termite control (UNEP, 2000).
Mirex, structurally similar to the now deregistered
cyclodiene insecticide chlordecone (Kepone), was
produced in smaller quantities and used for ant
control, often in the form of a bait (Table 2-7).
Mirex was also used in the United States as a
fire retardant additive (U.S. EPA, 1998).
2-6
-------
Profiles of the POPs
Chemical
information
Persistence
Properties related to
environmental transport
Bioaccumulation
Acute toxicitya
jQircmicJioxicity
US production
history
US use history
Current (2001)
international
production and use
Table 2-5. Chlordane
CAS number: 57-74-9
:l Cl
Molecular formula:
C10H6C18
^
Half-lives : -1.3-4.2 days (air) [[[
-1.1-3.4 years (water)
-1.1-3.4 years (soil) _
Henry's law constant: 4.8 x 10~5 atm-m3/mol at 25 C
Vapor pressure: 1 x 10~6 mm Hg at 20°C
Solubility in water: 56 ug/L at 25°C
K (octanol-water partition coefficient) — 106
Oral LD50 = 283 mg/kg
, =_58jOjng/k£Jrabbd^
iM^^l^ljmlMl^MiHIML
_____b^ ^^^^ _ ^^^^
Average annual US usage prior to 1983b: >1600 tonnes (3.6 million Ibs)
No present production, import, or export in USA
- Insecticide in agriculture and home gardens
- Termiticide
- All uses canceled by 1988
- China, Singapore0
- Chlordane is still used in a number of countries in Africa and Asia,
primarily as a termiticide
aWare, 1989.
bEPA, 1998.
The basic producers are Sino Agro-Chemical Industry Ltd. (China) and Agsin Pte. Ltd. (Singapore) (Meister,
2000).
A number of alternative chemical control strate-
gies can now be used effectively to replace the
cyclodienes, although most do not exhibit the
same persistence in soil. These include long-
acting organophosphate pesticides and several
synthetic pyrethroids (Mauldin et al., 1987; Su et
al., 1993; Kard, 1996). Nonchemical alterna-
tives, such as physical barriers and heat treat-
ment, can provide effective and less toxic ter-
mite control in buildings (Grace and Yates, 1999;
Pearce, 1997; Woodrow and Grace, 1998).
DDT was the first organochlorine insecticide de-
veloped, and is probably the most famous and
controversial pesticide ever made. Worldwide, an
estimated 2 million tons have been produced and
applied since 1940, primarily in agriculture (Table
2-8) (Ware, 1989; ATSDR, 2000). Unlike many
of the other synthetic organic pesticides developed
later, DDT exhibited relatively low mammalian
toxicity, was initially highly effective at controlling
a variety of insect pests, and, perhaps most im-
portantly, was very inexpensive to produce. This
unique combination of properties led to DDT's
widespread use in public health, beginning with
the control of louse-borne typhus during World
War II. DDT was a central tool in the malaria
eradication programs of the 1950s and 1960s
(Figure 2-4). Although the malaria eradication
goal proved elusive in much of the tropical world,
DDT nonetheless contributed to improved health
and saved countless lives in many malarious coun-
tries (Oaks et al., 1991).
In the United States, malaria had been largely
eradicated prior to the introduction of DDT, al-
though DDT was widely used for nuisance mos-
quito control. The primary use of DDT was as a
broad-spectrum insecticide on agricultural crops,
principally cotton (-90% of total use), but also on
potatoes, corn, tobacco, and apples, and against
-------
Profiles of the POPs
Chemical
information
Persistence
Properties related to
environmental transport
Bioaccumulation
Table 2-6. Heptachlor
CAS number: 76-44-8
Molecular formula: C10H5C17
Molecular weight: 373.32
Cl Cl
Half-lives: -1.3-4.2 days (air)
-0.03-0. 11 years (water)
___^_
Henry's law constant: 2.3 x 10~3 atm-mVmol
Vapor pressure: 3 x 10~4 mm Hg at 20°C
-- _
K (octanol-water partition coefficient)
BAF/BCF ~ 8,500
Acute toxicity
US production
history
Oral LD50 = 147-220 mg/kg
Dermal
200mQ/kgrat); 119-320 mg/kg (rabbit)
Years produced3:
No present production, import, or export in USA
US use history
- Termiticide
- Insecticide for control of fire ants in underground cable boxes
- Most uses canceled by 1978, all uses canceled 2000
Current (2001)
international
production and use
- No known current producers, although an exemption has been requested for
use as a pesticide and pesticide solvent
- Insecticide for control of termites and other soil insects by several
countries
- Solvent n Ptiad2:>y
forest pests (Ware, 1989; U.S. EPA, 1998;
ATSDR, 2000). DDT use in the United States
peaked in 1961, but began to decline thereafter
because of several technical complications. One
Figure 2-4. Anopheles mosquito, vector of malaria and
target of DDT.
Photo: WHO/TDR/Gwadz
problem was mounting resistance, as continual
exposure to the heavily used and persistent
chemical selected for resistant insects. DDT
resistance was observed in apple pests as early
as 1954 (Outright, 1954). By 1984, DDT resis-
tance was documented in 233 species of insects
and mites worldwide, including many important
agricultural pests (Georghiou, 1986). DDT's
broad spectrum of activity against virtually all
insects, pests and beneficials alike, and its long
environmental persistence also led to serious
secondary pest problems. Secondary pests are
normally suppressed by natural predators, but
their populations spiral upward out of control
when the predators are killed by DDT. For ex-
ample, an important pest of California citrus, the
cottony cushion scale, was controlled by the
Vedalia beetle until growers in 1946 applied
DDT to control a different pest (Figure 2-5).
The DDT applications killed off the predator but
not the white-colored scale, whose populations
2-1
-------
Profiles of the POPs
Chemical
information
Persistence
Properties related to
environmental transport
Bioaccumulation
Acute toxicity
Chronic toxicity
Past production in
USA
History of use(s) in USA
Current (2001)
international
production and use
Table 2-7. Mirex
CAS number: 2385-85-5
Molecular formula: C,nCL
Q
-—,
__________
-0.34-1.14 years (water)
> 3.4 years (soil)
air
Henry's law constant3: 8.3 x 10 atm-m /mol at 20 C
Vapor pressure: 3 x 10~7 mm Hg at 25°C
jSdubilitj^ £L?J;f£______
K (octanol-water partition coefficient) ~ 1069
BAF/BCF ~ 2,400,000
Oral LD50 = 306 mgAg
Dermal_LD5Q_=_800 mg/kg_____^^
ReferencedosejRfD) = 2 x 10;4 mg/kg/day (UP = 300)
T9544976"1
Years produce'
Total US production
1963 and 1968C.
No present production, import, or export in USA
1500 tonnes (3.3 million Ibs). Peak US usage between
- Insecticide for fire ant control
- Industrial fire retardant additive
All pesticide uses canceled by 1977
No known current producers. China has requested a production exemption
for termiticide manufacture
An exemption has been requested by two countries for use in termite
control
aAMAP, 1998.
bEPA, 1998.
CEPA, 1998. Total is for Hooker Chemical Company only. Two other US companies also manufactured mirex
during this time.
exploded, covering trees so densely the orchards
looked snow-covered. The Vedalia beetle had to
be reintroduced at a cost of up to $1 per beetle
Figure 2-5. Vedalia beetles, a nontarget species killed by
DDT, eating cottony cushion scale.
Photo: J.K. Clark, University of California IPM project
to regain control of the scale (DeBach and
Rosen, 1991).
At the same time that DDT use peaked in the
1950s and 1960s, there was mounting evidence
of the environmental impacts from DDT and its
long-lived metabolites, DDE and ODD (Ratcliffe,
1967; Wurster et al., 1965; Riseborough, 1972).
These DDT, DDE, and DDD concentrations are
often added together and reported as sum-DDT,
s-DDT, or S-DDT values. Their impacts were
particularly severe on bird populations through
eggshell thinning and chick mortality in raptors
(e.g., bald eagles, falcons) and oceanic birds
(e.g., pelicans) (Beyer et al., 1996) (Figure 2-6).
Although DDT was considered to exhibit rela-
tively low acute mammalian toxicity, concerns
were being expressed about potential chronic
reproductive impacts on humans (O'Leary et al.,
2-9
-------
Profiles of the POPs
Chemcial
information
Table 2-8.
DDT
h
CAS number: 50-29-3 Cl ^ ^ (
Molecular formula: C14H9C15 \—V
Molecular weight: 354.49 (
H
''^J^0
XJI3
Persistence
Properties related to
environmental transport
Bioaccumulation
_______
0.34- 1.1 4 years (water)
___
Henry's law constant: 1.29 x 10~s
Vapor pressure3: 1.6 x 10~7 mm Hg at 20°C
Solubility in water: 1.2-5.5 ug/L at 25°C
Acute toxicity
in mammals5
Chronic toxicity
KOW (octanol-water partition coefficient) ~ I0619
BAF/BCF- 1,800,000
Oral LD50 = 87 mg/kg
Dermal LD^ 1,931 mgAg (rabbit)
Reference dose (RfD) = 5 x 1Q-4 mg/kg/day (UF = 100)
US production Years produced5'0: 1940 - (none by 1993)
history Peak US production in 1962C: 82,000 tonnes (180 million Ibs) (Metcalf, 1995)
No present production, import, or export in USA.
Contaminant of the pesticide dicofol.
US use history - Broad spectrum insecticide on many crops
- Most uses canceled by 1972. All uses canceled by 1989
Current (2001)
international production
and use
Production: China, India
Insecticide used in at least 25 countries for control of insect vectors of human
disease, particularly malaria. Used in the production of dicofol.
aHSDB, 2002.
Ware, 1989.
CEPA, 1998.
1970; Saxena et al., 1981; Wassermann et al.,
1982). Subsequent information has shown p,p'-
DDE, a DDT metabolite, to bind to the androgen
receptor, antagonizing androgen action (Kelce et
al., 1995, 1997; Gray et al., 1999; Maness et
al., 1998; NAS, 1999). A recently published
human epidemiological study has demonstrated
an association between DDT concentrations and
increased preterm human births, a major con-
tributor to infant mortality. Longnecker et al.
Figure 2-6. Bird eggshell effects after population DDE
exposure. A. Cracked shell. B. Dented shell.
Photo: US FWS
(2001) analyzed frozen maternal serum samples
that had been collected between 1959 and 1965
and stored as part of the U.S. Collaborative
Perinatal Project (CPP). During this time of peak
DDT use in the United States, the median DDE
concentration of 25 mcg/L was several-fold
higher than current U.S. levels. Taking into
consideration data on potential confounding
variables collected during this study (age, birth
order, socioeconomic status, etc.), the associa-
tion of increasing serum DDE concentrations with
preterm birth was highly statistically significant
(Figure 2-7, trend p<0.0001). Dose-response
data were consistent with serum DDE levels
above 10 meg A- affecting the risk of preterm
birth. These human epidemiological findings
warrant consideration when balancing the risks of
DDT against its benefits for malaria vector con-
trol and the costs of alternatives.
All uses of DDT in the United States were can-
celled by EPA in 1972, primarily because of
2-70
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Profiles of the POPs
Chemical
information
Persistence
Properties related to
environmental transport3
Bioaccumulation
Acute toxicity in
mammalsd
Chronic toxicity
US production
history
US use history
Table 2-9. Toxaphene3
CAS number: 8001-35-2
Molecular formula: C10H10C18
Molecular weight: 413.82
Half-lives: -4.2-12.5 days (air)
>3.4 years (water)
>3.4 years (soil)
Henry's law constant: 6.3 x 10~2 atm-m3/mol
Vapor pressure*1: 5 x 1Q-6 - 0.4 mm Hg at 20°C
Solubility in water: 550 ug/L at 20°C
K^ (octanol-water partition coefficient)0 ~ 1048-1066
BAF/BCF- 1,100,000
Oral LD50 = 40 mgAg
Dermal LD5Q = 600 mg/kg (rabbit)
Reference dose (RfD) = under development
Years produced8: 1946-1990s
Peak US production in 1972b: 21,000 tonnes (46 million Ibs)
No present production, import, or export in USA
- Insecticide to control cotton pests and plague grasshoppers and for mange
control on cattle
- Most uses canceled by 1982
- All uses canceled by 1990
No known producers
No known registered uses
Current (2001)
international
production and use
aToxaphene is a complex mixture of various chlorinated bornanes and camphenes. There are discrepancies
noted in the literature regarding physical properties; see ATSDR 1996b for details.
bATSDR, 1996b.
cFisk et al., 1999.
Ware, 1989.
eEPA, 1998.
3.5
i
co 3
I 2-5
B
5
1.5
0.5
DDE and the Risk of Preterm Birth
4.2 5.4
<15 15-29 30-44 45-59 60+
Serum DDE - micrograms/liter
Figure 2-7. Graph of the association between maternal
serum DDE levels and preterm birth risk. Adjusted odds
ratios and 95% confidence intervals (from Longnecker et
al, 2001).
positive cancer results in rodent bioassays. DDT
production in the United States for export oc-
curred until at least 1985 (ATSDR, 2000). DDT
use for disease (mostly malaria) vector control
continues in an estimated 25 or more developing
countries, primarily because of its low cost and
persistence (WHO, 1999). Many other insecti-
cides are available for indoor house spraying
(Chavasse and Yap, 1997), but DDT's lower cost
remains an advantage, at least in some countries
(Walker, 2000). Other approaches to disease
control such as case detection and treatment, or
pyrethroid-treated bednets, may prove more
cost-effective and sustainable in the long term
(Goodman et al., 1999). For the future, the
Stockholm Convention strives for a balance
among the public health benefits of DDT for
malaria control, the availability and cost of alter-
natives, and the impacts of DDT on ecosystems
2-77
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Profiles of the POPs
Chemical
information
Table 2-10. Hexachlorobenzene (HCB)
CAS number: 118-74-1
Molecular formula: C6C16
Molecular weight: 284.78
ci
Persistence
ties related to
environmental transport
Bioaccumulation
Acute toxicity in mammals3
Chronic toxicity
US production
history
US use and
source history
Half-lives: ~ 417-1250 days (air)
>3.4 years (water)
>3.4 years (soil) _
~ afm-m37mol at 2(FC
Vapor pressure: 1.089 x 10 5 mm Hg at 20°C
^Solubilit^
KOT (octanol-water partition coefficient) ~ 10 5
BAF/BCT~110,000
international
production and use
_
_
Years produced as a fungicide3: 1945-late 1970s
HCB is produced as a byproduct or contaminant of certain chemicals.
Estimated annual US production as a byproduct or impurity range from
68-689 tonnes (0.15-1.52 million Ibs), the majority of which is destroyed
jDnsite _
-Fungicide for seed and wheat
-Currently imported for use as an intermediate; import anticipated to cease in
_J:uturejtoj^ _
-No current production for fungicide applications.
-No current reported uses as a fungicide.
-Several countries have requested exemptions as an intermediate, a closed-
system, site-limited intermediate, or contaminant in pesticides.
and, potentially, human health. While working
toward a goal of reducing and ultimately elimi-
nating the use of DDT, parties may use DDT
only for disease vector control in accordance with
World Health Organization recommendations
(UNEP, 2000).
Toxaphene is a mixture of at least 670 chlori-
nated terpenes, produced through chlorinating
camphene (Table 2-9; image shown is a chlori-
nated bornane structure). Its primary use was on
cotton, where it was generally applied with an-
other insecticide, first DDT and subsequently
organophosphate insecticides such as methyl
parathion. U.S. production of toxaphene
peaked in 1972, when it was the most heavily
manufactured pesticide in the country, largely as
a replacement for DDT. Toxaphene was also
used as a piscicide to eradicate fish species
considered undesirable for sport fishing in
Canada and the northern United States (U.S.
EPA, 1998). Fish restocking efforts were some-
times difficult because of the longevity of active
toxaphene residues, highlighting the problem of
environmental persistence. Most registered uses
in the United States were withdrawn in 1982, on
the basis of studies showing tumors in tox-
aphene-exposed laboratory animals, evidence of
acute toxicity to aquatic organisms, and impacts
on nontarget animals including endangered spe-
cies.
Worldwide, toxaphene was one of the most
widely used agricultural insecticides during the
1960s and 1970s, primarily for control of cotton
pests. Between 1950 and 1993, when all pro-
duction ceased in the United States, an esti-
mated 2.6 billion pounds had been manufactured
worldwide (ATSDR, 1996b). Stockpiles of tox-
aphene continue to threaten the environment in
some areas. For example, in Nicaragua, 230
metric tonnes of toxaphene were recently re-
ported stockpiled in a zone at high risk for earth-
quakes near Lake Managua, a unique ecosystem
2-72
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Profiles of the POPs
Table 2-11. Polychlorinated Biphenyls (PCBs)
Example: Aroc/or 1254 mixture
~CherrJAca\ ^-^^^
information Molecular formula: Ci2Cl(X + V)
INfolecular^we^
Persistence Half-lives: -4.2 days (air) [PCB congener group]
-5.7 years (water) [PCB congener group]
-1.14 years (soil) [PCB congener group]
Properties related to
environmental transport3
Henry's law constant: 2.0 x 10~3 atm-m3/mol at 25 C
Vapor pressure: 7.71 x 10~5 mm Hg at 25°C
^ at 240C
Bioaccumulation
Acute toxicity in mammals
Chronic toxicity
US production history
(octanol-water partition coefficient) -
Reference dose (RfD) = 2 x 1Q-5 mg/kg/day
(UF = 300), under review
^ATSJDR^^ _
Years PCBs produced: 1929-1977; banned under TSCA Section 6(e) effective
1979
Peak PCB production 1970, —3900 tonnes (8.5 million pounds) annually for all
PCBs
^ _
Current (2001) US source
and_use history
Dun-en
international
Use allowed if in certain existing equipment; environmentally sound
destruction/disposal_after_service life of equipment
Manufacture discontinue ''
No recorded new uses; widespread residual use in existing equipment and
products
bAMAP, 2000.
and home to many rare species of wildlife
(EARTH, 2000).
Hexachlorobenzene (HCB) is included under all
three general categories of POPs: as a pesti-
cide, an industrial chemical, and an unintended
byproduct (Table 2-10). HCB was introduced as
a pesticide in the United States in 1945 for
antifungal seed and soil treatment. All U.S.
pesticide uses were canceled in 1985 (Ware,
1989; ATSDR, 1996c). The human toxicity of
HCB was sadly demonstrated in Turkey during
the late 1950s, when an estimated 3,000 to
4,000 people ingested bread inadvertently made
from HCB-treated grain at approximately 2 kg
HCB per 1,000 kg wheat. The HCB led to
porphyria cutanea tarda in adults, a metabolic
defect of blocked hemoglobin synthesis that
causes light-sensitive skin lesions, colored urine,
and, in some cases, death. All children born to
porphyric mothers during this epidemic died,
with an estimated 1,000 to 2,000 children dying
from related skin lesions, exacerbated by the
HCB transfer in breast milk (Peters et al., 1982,
1987).
Industrial uses of HCB have varied, including
pyrotechnic coloring in military ordnance, syn-
thetic rubber production, and as a chemical inter-
mediate in dye manufacture and organic chemi-
cal synthesis (Bailey, 2001). There are no
current uses of HCB as an end product in the
United States, although it is imported for use as
a production intermediate. An exemption is
available under the Stockholm Convention for the
use of HCB as a closed-system, site-limited inter-
mediate. HCB is still produced as an unintended
byproduct during the manufacture of chlorinated
solvents and as an impurity of certain pesticides
2-13
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Profiles of the POPs
Table 2-12. Polychlorinated Dibenzo-p-Dioxins
Example: 2,5,7,8-TetrachIorodibenzo-p-dioxin (TCDD)
Themicai ^^^^
information
for TCDD
Molecular formula: C12H4C14O2
Molecular weight: 322.0
Persistence
Properties related to
environmental transport3
Bioaccumulation
Acute toxicity
in mammals3
Chronic toxicity
Major sources
(US and international)
aATSDR, 1998.
Half-lives: 4.2-12.5 days (air) [range for PCDDs]
-0.11-0.34 years (water) [range for PCDDs]
j-OSfyjjrea^
Henry's law constant: 1.6 x 10~5 - 1.0 x 10"4 atm mVmol at 258Cf
Vapor pressure: 1.5 x 10~9 - 3.4 x 1Q-5 mm Hg at 25°C
JSohobm^^
Kow (octanol-water partition coefficient) ~ 1069
_BAF/BCT~_130,000
Hamster oral LD50 = 5051 mcgAg
Rat oral LD50 =22-165 mcgAg
Mink oral LD50 = 4.2 mcgAg
^
Under EPA review: www.epa.gov/ncea/dioxm.htm
chronic M^ (UF = 100)
Municipal and medical waste incineration
Open and barrel burning of waste
Elemental chlorine bleach pulp and paper manufacture
Certain thermal processes in the metallurgical industry
Selected chemical manufacturing processes, e.g., 2,4,5-trichlorophenol
production (now ceased)
(picloram, PCNB, chlorothalonil, DCPA, and
PCP) (ATSDR, 1996c). It is also created and
emitted during incineration practices. Due to its
chemical structure, HCB is extremely stable,
globally distributed, and considered among the
most persistent of all POPs.
PCBs are a mixture of synthetic organic chemi-
cals with the same basic chemical structure and
similar physical properties, ranging from oily
liquids to waxy solids (Table 2-11). Because of
their nonflammability, chemical stability, high
boiling point, and electrical insulating properties,
PCBs were used in hundreds of industrial and
commercial applications, including electrical,
heat transfer, and hydraulic equipment; as plasti-
cizers in paints, plastics, and rubber products;
and in pigments, dyes, and carbonless copy pa-
per. First manufactured in 1929, more than 1.5
billion pounds of PCBs were manufactured in the
United States (plus elsewhere in the world) be-
fore domestic production ceased in 1977.
PCBs are principally addressed under the
Stockholm Convention as intentionally produced
industrial chemicals. PCBs are also closely linked
to the polychlorinated dioxin and furan byproduct
POPs for the following reasons:
•£ Coplanar PCBs have a similar chemical struc-
ture and spatial configuration to the polychlo-
rinated dioxins and furans, and much of the
toxicity of all three congener groups is linked
through a common mode of action (mediated
through binding to the aryl hydrocarbon [Ah]
receptor in the cell) and the concept of dioxin
toxicity equivalence (see under byproduct
POPs).
2-74
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Profiles of the POPs
Table 2-13. Polychlorinated Dibenzofurans
Example: 2,3,7,8-TetrachIorodibenzofuran (TCDF)
Chemical
information for
JTCDF
Persistence
Properties related to
environmental transport5
CAS number1: 51207-31-9
Molecular formula: CHC1O
Half-lives: 4.2-12.5 days (air) [range for PCDFs]
-0.11-0.34 years (water) [range for PCDFs]
— 1.1-3.4 years (soil) - for all furans [range for PCDFs]
Henry's law constant3: 1.48 x 10 atm-m3/mol
Vapor pressure3: 9.21 x 10~7 mm Hg at 25°C
Solubility in waterb: 0.692 ug/L at 26°C
Bioaccumulation
KOW (octanol-water partition coefficient)
BAF/BCF~61,000
1061
-
Chronic toxicity
Under review: www.epa.gov/nceo/dioxm.htm
Major sources
nd international)
See for dioxins
bHSDB, 2002.
•'v Burning and high-temperature treatment of
PCB mixtures can lead to the creation of
polychlorinated dibenzofurans (PCDFs), further
exacerbating the potential toxicity from
PCBs. This occurred during the Yusho and
Yu-Cheng poisoning incidents in Japan and
Taiwan, respectively, where the cooking of
rice oil contaminated with PCBs resulted in
the production of PCDFs. The combined
presence of PCBs and PCDFs in the cooked
food caused chloracne and other toxic effects
in the adults, and fetal mortality and develop-
mental defects in their offspring (Rogan et al.,
1988; Hsu et al., 1994).
;*; Like polychlorinated dioxins and furans, PCBs
can be produced in small amounts during
incineration processes and are therefore in-
cluded in the unintentional byproduct category
under the Stockholm Convention.
Beyond the rice oil contamination poisonings,
PCB toxicity has been demonstrated in wildlife
and humans following environmental exposures.
As detailed in the chapters to follow, PCBs have
been associated with reproductive effects in
wildlife populations in the Great Lakes (Chapter
3) and far out in the North Pacific Ocean (Chap-
ter 6). For humans, increased PCB concentra-
tions in children from environmental exposures
are associated with neurodevelopmental impacts
(Fein et al., 1984; Jacobson and Jacobson,
1996), findings supported by followup studies in
the Great Lakes region (Lonky et al., 1996;
Stewart et al., 2000) and in Dutch children
(Patandin et al., 1999) (Chapter 4).
Concern over the toxicity and persistence of
PCBs in the environment led Congress in 1976
to enact Section 6(e) of the Toxic Substances
Control Act (TSCA). This includes prohibitions
on the manufacture, processing, and distribution
in commerce of PCBs. Under the Stockholm
Convention there is a global ban on the manufac-
ture of PCBs (UNEP 2000). Because of the
magnitude of past use of PCBs and the continu-
ing economic importance of previously manufac-
tured PCB-containing equipment, countries must
make determined efforts to identify, label, and
remove PCB-containing equipment from use by
2025. During this interval, the Stockholm Con-
vention mandates a series of measures to reduce
exposures and risk from further releases of PCBs
to the environment, accompanied by prohibitions
on reuse and export and import, except for the
purpose of environmentally sound waste disposal.
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Profiles of the POPs
The term "dioxin" refers to a group of chemical
compounds that share certain similar chemical
structures and toxicological characteristics.
Thirty toxic dioxin-like compounds exist and are
members of three closely related families:
PCDDs, PCDFs, and coplanar PCBs. The term
dioxin is also used for the most well-studied and
toxic of the dioxins, 2,3,7,8-tetrachlorodibenzo-
p-dioxin (TCDD) (Table 2-12). PCDDs and
PCDFs (Table 2-13) are not created intentionally,
but can be produced inadvertently in nature and
by a number of human activities. Combustion
(Figure 2-8), elemental chlorine bleaching of pulp
and paper (Figure 2-9), certain types of chemical
manufacturing and processing, and other indus-
trial processes all can create small quantities of
dioxins. PCBs are no longer manufactured in the
United States, but formerly were widely used in
electrical equipment as coolants and lubricants.
PCBs can also be formed in a similar manner to
dioxins as byproducts of combustion processes
(see previously).
Dioxins have been central to a number of environ-
mental controversies in recent decades. Dioxin
(2,3,7,8-TCDD in particular) was a contaminant of
the herbicide 2,4,5-trichlorophenoxyacetic acid
(2,4,5-T) sprayed in Agent Orange defoliant during
Figure 2-8. Stack emissions, New Orleans, Louisiana,
1973.
Photo: U.S. EPA
the Vietnam War (Figure 2-10). Ensuing sprayer
(Operation Ranch Hand personnel), soldier, and
civilian exposures have resulted in ongoing inquir-
ies, research, and veterans' health benefits com-
pensation (IOM, 1994). In 1976, an explosion at
a trichlorophenol herbicide production plant in
Seveso, Italy, led to widespread environmental
contamination, local livestock and wildlife mortality,
very high human exposures and clinical illness
(e.g., chloracne, a severe and prolonged acne-
form condition) (Figure 2-11), and evacuation of
the surrounding region (Bertazzi et al., 1998).
Residential dioxin exposure and evacuation also
occurred at Times Beach, Missouri, following the
spraying of dioxin contaminated waste oil for
dust control in the early 1970s (Webb et al.,
1984). In occupational studies, cancer mortality
increases have been reported in several groups of
workers exposed to dioxin during herbicide pro-
duction (Steenland et al., 2001; Ott and Zober,
1996; Becher et al., 1998). The US EPA is
currently assessing the impacts of dioxin on the
general public in its draft document "Exposure
and Human Health Reassessment of 2,3,7,8-
Tetrachlorodibenzo-p-Dioxin (TCDD) and Related
Compounds" (www.epa.gov/ncea/dioxin.htm).
Dioxins have the potential to produce an array of
adverse effects in wildlife and humans. Dioxins
can alter the growth and development of cells in
ways that can lead to many kinds of impacts.
These include adverse effects upon reproduction
and development, suppression of the immune
system, chloracne, and cancer. Although data on
risks to children are limited, fetuses, infants, and
children may be more sensitive to dioxin expo-
sure because they are exposed during critical
windows of development and during rapid
growth.
Dioxins are believed to exert these toxic effects
in similar ways; that is, they share a common
mode of toxicity. As a result, scientists use an
approach that adds together the toxicity of indi-
vidual dioxins in order to evaluate complex envi-
ronmental mixtures to which people are ex-
posed. Because dioxins differ in their toxic
potential, the contribution of each component in
2-76
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Profiles of the POPs
Figure 2-9. Pulp mill effluent, a source of poly-
chlorinated dioxins and furans, Columbia River, 1970s.
Photo: U.S. EPA
the mixture must be accounted for in estimating
the overall toxicity. To do so, international
teams of scientists have developed toxicity
equivalence factors (TEFs) that compare the
toxicity of different dioxins to the most toxic
congener, 2,3,7,8-TCDD. Given these factors,
the toxicity of a mixture can be expressed in
terms of its toxicity equivalents (TEQ), which is
the amount of 2,3,7,8-TCDD exposure it would
take to equal the combined toxic effect of all the
dioxins found in that mixture.
Most dioxin enters ecological food webs by being
deposited from the atmosphere, either directly
following air emissions or indirectly by processes
that return dioxins already present in the environ-
ment to the atmosphere. Once they reach the
environment, dioxins are highly persistent and
Figure 2-10. Aircraft spraying Agent Orange, contami-
nated with dioxin, in Vietnam.
Photo: USAF
Figure 2-11. Chloracne caused by high exposure to dioxin.
Photo: A. Geusau (Geusau et al., 2001/EHP)
2-77
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Profiles of the POPs
can accumulate in the tissues of animals. Most
dioxin exposure occurs through the diet, with
more than 95% of dioxin intake for a typical
person coming through dietary intake of animal
fats. Fortunately, dioxin levels in the environ-
ment have declined significantly since the 1970s,
following EPA regulatory controls and industry
actions. EPA's best estimates of emissions from
sources that can be reasonably quantified indi-
cate that dioxin emissions in the United States
decreased by about 75% between 1987 and
1995, primarily through reductions in air emis-
sions from municipal and medical waste incinera-
tors. Substantial further declines continue to be
documented.
Agency for Toxic Substances and Disease Registry
(ATSDR). 1993a. Toxicological profile for aldrin/
dieldrin. U.S. Department of Health and Human Ser-
vices.
ATSDR. 1993b. Toxicological profile for heptachlor/
heptachlor epoxide. U.S. Department of Health and
Human Services.
ATSDR. 1994. Toxicological profile for
chlorodibenzofurans. U.S. Department of Health and
Human Services.
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Profiles of the POPs
U.S. Department of Health and Human Ser-
vices, National Library of Medicine (NLM;
www.nlm.nih.gov)
- Medline/PubMed, covering medical litera-
ture;
- Toxnet, toxicology data network;
- HSDB, Hazardous Substances Data Bank,
focusing on the toxicology of potentially
hazardous chemicals, with information on
human exposure, industrial hygiene, emer-
gency handling procedures, environmental
fate, regulatory requirements, and related
data
U.S. Department of Health and Human Ser-
vices, Agency for Toxic Substances and Dis-
ease Registry (ATSDR; www.atsdr.cdc.gov)
- ToxFAQs, summaries of hazardous sub-
stance information;
- Toxicological Profiles of hazardous sub-
stances (www.atsdr.cdc.gov/toxpro2.html)
U.S. Environmental Protection Agency (U.S.
EPA; www.epa.gov)
- IRIS, Integrated Risk Information System
(IRIS), a database of human health effects
that may result from exposure to various
substances found in the environment
(www.epa.gov/iris)
- PBT, Persistent Bioaccumulative Toxic,
home page, containing summaries of PBT
chemicals, EPA action plans, and regula-
tory initiatives (www.epa.gov/pbt)
- ECOTOX database system, providing
chemical-specific toxicity values for aquatic
life, terrestrial plants, and terrestrial wildlife
(www.epa.gov/med/databases/
databases, htm l#aquire)
U.S. Department of the Interior, U.S. Geo-
logical Survey, Patuxent Wildlife Research
Center (www.pwrc.nbs.gov/research/ecr/)
- Contaminant Exposure and Effects Terres-
trial Vertebrates Database
- Contaminant Hazards Review On-Line
For further information on toxicology data sources, see Toxicology, Volume 157, Issues 1-2, Pages 1-164,
12 January 2001. For federal sources, see specifically Brinkhuis, 2001. Hard copies of many federal
documents are available from performing agencies, the Government Printing Office, and/or the National
Technical Information Service (NTIS Tel: 703-605-6000).
2-22
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Chapter 3
^m m
Persistent Organic Pollutant
Residues and their Effects on Fish
and Wildlife of the Great Lakes
Introduction
Tor nearly two centuries the Great Lakes of
North America have been the receiving waters
for industrial and municipal wastes. Their story
is illustrative of persistent organic pollutant
(POPs) impacts in many lakes, streams, and
rivers across the United States. The contamina-
tion of the Great Lakes with persistent and
bioaccumulative compounds, including those
designated as POPs under the Stockholm Con-
vention, has been studied in detail and demon-
strated to cause population-level effects on wild-
life. The large size of the lakes had led to the
commonly held, yet mistaken, belief that it was
impossible to contaminate them sufficiently to
cause adverse effects. As human populations
and industrialization of the Great Lakes basin
increased, and the complexity and magnitude of
the industries grew, it became apparent that it
was indeed possible to contaminate the lakes to
the extent that adverse effects would be ob-
served. The release of persistent and
bioaccumulative compounds eventually resulted
in thresholds for adverse effects being exceeded
in a number of wildlife populations.
Literally thousands of
contaminants can now
be found in the tissues
of fish and wildlife of
the Great Lakes (Figure
3-1). Concentrations of
all of the compounds
designated for control
under the Stockholm
Convention have been
found at elevated levels
in Great Lakes wildlife,
and all could have con-
tributed to some of the
Figure 3-1. Chromatogmm showing organochlorine
compounds in extract of Great Lakes fish.
Photo: J.P. Giesy
observed adverse effects in some species. How-
ever, several of the POPs were responsible for
most of the observed effects. These include the
insecticides dieldrin and DDT, the industrial poly-
chlorinated biphenyls (PCBs), and the byproducts
of incineration and chemical production, poly-
chlorinated dibenzo-p-dioxins (PCDDs) and poly-
chlorinated dibenzofurans (PCDFs). Although
these POPs may have had adverse impacts on a
number of species, their effects have been best
documented for a few sentinel species such as
lake trout (Saluelinus namaycush) (Giesy and
Snyder, 1998), bald eagles (Haliaeetus
leucocephalus) (Bowerman et al., 1995, 1998),
colonial fish-eating water birds such as the cor-
morant (Phalacrocorax auritus) and Caspian
tern (Sterna caspia) (Giesy et al., 1994a,b), and
the mink (Mustela uison) (Giesy et al., 1994c;
Tillitt et al., 1996).
The experiences in the Great Lakes have re-
sulted in a greater understanding of the potential
hazards of releasing persistent, bioaccumulative,
toxic compounds into the environment. Many of
the substances are no longer manufactured or
their use is heavily restricted. Concentrations of
^mmmmmmm^^^^^^^^ the most problematic
compounds such as
DDT and PCBs have
declined, but the cur-
rent rates of decline
are very slow, such that
it will be a long time
before the concentra-
tions in both fish and
birds of the Great
Lakes environment
reach "background"
concentrations (Figures
3-2 to 3-4) (Giesy and
3-1
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
25
L Superior
L Huron
L. Michigan
L. Ontario
72 74 76 78 80 82 84 86 88 90 92 94 96
Year
Figure 3-2. Concentrations of PCBs in lake trout from
the four uppermost Great Lakes between 1972-1993.
Redrawn from MDNR (2001).
Snyder, 1998). The trends for PCBs and DDTs
are similar to those for the other Stockholm
Convention POPs in both fish and birds. These
trends demonstrate several things. First, fish and
wildlife became contaminated with POPs resi-
dues soon after they were introduced, reaching
maximum concentrations in the early 1970s.
Second, when use of these compounds was re-
stricted in North America, concentrations began
decreasing immediately, and within approxi-
mately 20 years had decreased to concentrations
L Superior
L. Huron
L. Michigan
L. Ontario
70 72 74 76 78 80 82 84 86 88 90 92 94 96 98
Year
20
18
16
|14
Concentration (m
_iO ho *». o> oo o ^
£ ;
D
y
A
A
D A
n An
870 1975 1980 1985 1990 1995 2000
Year
Figure 3-3. Concentrations of total DDTs in lake trout in
the four uppermost Great Lakes. Redrawn from MDNR
(2001).
Figure 3-4. Mean wet weight concentrations of PCBs and
DDE in double-crested cormorant eggs collected from the
Great Lakes (yellow squares = DDE; red triangles =
PCBs). Data from Environment Canada, www.ec.gc.ca/
ind/English/Toxic/default.cfm
at or near the threshold for effects. Even though
the manufacture of these compounds ceased
over 25 years ago, they remain at significant
concentrations in wildlife. This lingering effect
occurs because concentrations of POPs, once
introduced into the environment, take a long
time to decrease to nondetectable concentra-
tions. Third, current concentrations in biota are
no longer decreasing at the same rate that they
once were. This slower rate is caused, in part,
by continued input to the lakes from reservoir
sources and from long-range atmospheric trans-
port (Giesy and Snyder, 1998; Simcik et al.,
1999).
In this report, we provide examples of the con-
centrations of selected POPs in wildlife and the
adverse effects that have been caused by expo-
sure to these compounds in the Great Lakes. To
do this, we perform a simple risk screening by
comparing concentrations of the POPs in tissues
or the diets of wildlife with the threshold concen-
tration for adverse effects. This comparison is
done by calculating hazard quotients (HQs) (Table
3-1). The HQ is the ratio of the measured con-
centration divided by the threshold concentration
for effects, using either tissue or dietary concen-
trations. For instance, the concentration of PCBs
in fish in the diet of a fish-eating bird can be
compared with the dietary No Observable Ad-
verse Effect Level (or concentration) (NOAEL).
3-2
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
Table 3-1. Calculation of Hazard Quotients (HQs)
Concentration in Fish
HQ =
NOAEL
HQs were calculated for:
Total PCBs
TCDD-TEQ (calculated)
Calculation of the HQ assumes animals eat only the
fish species of interest. This is a conservative or
"worst-case" estimate.
The NOAEL is the highest dose or concentration
at which no adverse effects have been observed.
Effects would be increasingly expected as doses
or concentrations rise above the NOAEL value.
A HQ value of 10 indicates that the dietary
concentration of PCBs is 10-fold greater than the
threshold for causing an adverse effect in the
piscivorous birds. Said another way, the concen-
tration of PCBs in that species of fish would
need to decrease by a factor of 10 before it
would not be expected to cause any adverse
effects to the birds that ate it. A HQ below 1
indicates that, to the best of our current knowl-
edge, adverse effects would be unlikely to occur.
Fish from all of the Great Lakes contain measur-
able concentrations of POPs and many other
contaminants (Giesy and Snyder, 1998). In gen-
eral, fish from Lakes Ontario and Michigan tend
to have the greatest concentrations of POPs.
Fish from Lake Ontario contain the highest con-
centrations of the insecticides mirex, DDT, and
dieldrin. The lowest concentrations of most
persistent, synthetic, chlorinated hydrocarbons
are observed in fish from Lake Superior. The
relatively high concentrations of toxaphene found
in fish from Lake Superior have been the subject
of several investigations (Swackhamer et al.,
1998; Shanks et al., 1999; Glassmeyer et al.,
2000). Concentrations of POPs in fish tissues
have decreased by a factor of approximately 25
since maximum concentrations were reached in
the lower Great Lakes in the mid-1970s. Al-
though there are differences among species and
locations, in general the trends for POPs are
either decreasing or stable.
There is considerable difference of opinion in the
literature about the extent to which effects on
Great Lakes fish should be attributed to and
among chemical contaminants. The types of
effects that have been reported in Great Lakes
fish include changes in behavior, reduced repro-
ductive success, thyroid enlargement and de-
creased thyroid hormone content, premature
sexual maturation in males, loss of secondary
sexual characteristics, lessened plasma gonadot-
ropin and gonadal hormone content, lessened
egg fertility, and greater than expected embryo
mortality and deformities (Leatherland, 1993).
There is strong evidence that the endocrine sys-
tems of salmonid fish such as lake trout and
chinook salmon are impaired, but at this time it
is not clear if these observed imbalances are the
result of exposure to POPs.
Populations of several fish species have changed
drastically from historical population levels.
Many factors have been implicated in these
declines, such as fishing, habitat loss, changes in
genetic strains, and effects of the sea lamprey,
in addition to a likely role for POPs and other
pollutants. Historically, the reproductive success
of salmonid fish in the Great Lakes was much
poorer than that of the same species raised on
the Pacific coast of the United States (Giesy et
al., 1986; Willford et al. 1991). These adverse
effects were often attributed to toxic substances,
but it was difficult to demonstrate a cause-effect
linkage. Specifically, several fish species have
exhibited reproductive deficits that could be
caused by exposure to POPs, although isolating
the causal agent(s) has proven problematic be-
cause the mixtures of chemicals to which the fish
are exposed vary over time and location.
Of the many contaminants measured in fish and
their eggs, DDTs, PCBs, polychlorinated dibenzo-
p-dioxins (PCDDs), and polychlorinated
dibenzofurans (PCDFs) are most often implicated
in adverse effects (Giesy and Snyder, 1998).
3-3
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
The highest concentrations of POPs observed in
fish eggs were for PCBs (11 mg/kg) and DDT (7
mg/kg). Based on these levels, it was initially
hypothesized that DDT and PCBs were most
likely responsible for the observed egg mortality
and reproductive toxicity. However, although
both DDT and PCBs could cause lethality of lake
trout eggs and fry in laboratory studies, the con-
centrations required to cause 30%-50% mortality
were as much as 25 times greater than the con-
centrations observed in the eggs at that time.
Thus, although concentrations of DDT observed
historically in Great Lakes salmonids were in the
range of the thresholds for adverse effects, as
determined in laboratory studies, it is unlikely
that these concentrations were the major cause
of adverse effects seen in the eggs of feral fish
from the Great Lakes. Current evidence indi-
cates that PCDD, PCDF, and some of the non-
and mono-ortho-substituted PCBs are principally
responsible for blue-sac syndrome (Figure 3-5)
and impaired reproductive performance of
salmonid species in the lower Great Lakes, espe-
cially for lake trout (Walker and Peterson 1991,
1994a,b; Zabel et al., 1995; Giesy and Snyder,
1998).
tions of lake trout have continued to reproduce
naturally in Lake Superior, and reproductive
success is improving (Curtis, 1990). A number
of studies have indicated that the lake trout
population recoveries in Lakes Huron and Michi-
gan are related to reduced toxic organic residues
in the eggs (see Giesy and Snyder, 1998, for a
comprehensive review).
Between 1978 and 1981, annual rearing mor-
talities in lake trout fry as great as 97% were
described for hatchery-reared fish (Mac et al.,
1985). Mortality in these studies could not be
attributed to disease or nutrition, and was char-
acterized by erratic swimming behaviors and loss
of equilibrium prior to death (swim-up syn-
drome). Poor survival was significantly correlated
with the source of eggs and sperm, more so than
the quality of the water in which the eggs were
reared (Mac et al., 1985). In addition, a number
of the adult lake trout produced fry that devel-
oped "blue sac" syndrome. This syndrome pre-
sents itself as an edematous (swollen with exces-
sive fluid) condition that results in fluid filling the
yolk sac, leading to a bluish color (Figure 3-5).
Lake Trout
Lake trout in Lake
Michigan have not
been naturally repro-
ducing successfully for
some time. The lake
trout populations in
both Lakes Michigan
and Huron are main-
tained by stocking
programs because
natural reproduction of
the populations is not
sufficient to sustain
populations (Willford et
al., 1981). Neverthe-
less, there has been
evidence of natural
reproduction in Lake
Huron (Weber and
Clark, 1984). Popula-
Figure 3-5. Effects of dioxin-like chlorinated hydrocarbons
on developing lake trout fry (Spitsbergen et al., 1991).
Photo: J. Spitsbergen (labels added). With permission of Elsevier Science.
Studies during the early
1980s by scientists at
the U.S. Fish and Wild-
life Service (FWS) re-
search laboratory in Ann
Arbor, Michigan, indi-
cated that the most
likely cause of poor
reproductive success
was toxic chemicals
(Mac et al., 1985;
Willford et al., 1981;
Giesy and Snyder,
1998). Their analyses
identified 167 chlori-
nated hydrocarbons in
fish, although many
more have been identi-
fied since. FWS re-
searchers considered it
unlikely that a correla-
tion could be established
3-4
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
between specific chemicals and effects because
of the large number of compounds observed in
fish. They believed contaminants must be in-
volved for the following reasons:
1. Mortality was restricted to lake trout from
southern Lake Michigan, which was also the
area where the lake trout contained the
greatest concentrations of PCBs and DDT.
The mortality rate of fry from Lake Superior
was small and that lake had the lowest con-
centrations of PCBs and DDT.
trout are among the most sensitive species to
dioxin toxicity. Thus, they can be used as senti-
nels for other species. Current concentrations of
2,3,7,8-tetrachlorodibenzo-p-dioxin TEQs remain
near the threshold for mortality in lake trout fry
(Walker and Peterson, 1994a). By 1988, con-
centrations of TEQs had decreased to 8 and 29
ppt in Lakes Michigan and Ontario, respectively.
These concentrations are less than the threshold
of approximately 40 ppt, but only slightly in the
case of Lake Ontario (see Giesy and Snyder,
1998, for further details).
2. Mortality occurred during the swim-up stage
of development, during which time fry were
most sensitive to the toxic effects of chemi-
cals.
3. The syndrome reached a maximum effect in
both lake trout and chinook salmon popula-
tions at the same time.
Thus, it was thought that DDT and PCBs were
most likely responsible for the observed toxicity.
However, no blue-sac disease, the syndrome
observed in the fry hatched from eggs of feral
females, was observed in laboratory studies of
the effects of DDT or PCBs. This finding sug-
gested that the complex mixture of contaminants
in fish, and the cause of blue-sac disease, had
not been completely identified or quantified.
Further studies on lake trout in the lower Great
Lakes demonstrated the link between blue-sac
disease/impaired reproductive performance and
the levels of PCDD, PCDF, and some of the non-
and mono-ortho-substituted PCBs measured as
dioxin toxicity equivalents (TEQs) (Walker et al.,
1991; Walker and Peterson, 1991, 1994a,b;
Cook et al., 1997; US EPA 2001). The thresh-
old for toxic effects of TEQ on lake trout sac fry
is approximately 30-40 ng/kg and the lethal
dose for 50% mortality (LD50) is approximately
47-70 ng/kg wet weight body burden (Figure 3-
6) (Walker et al. 1991; Walker and Peterson,
1994a,b). Toxicity is manifest from 1 week
prior to hatching through the sac-fry stage of
development (Spitsbergen et al., 1991). Lake
No measurements of historical concentrations of
TEQs in fish tissue are available. However, the
use of sediment TEQ concentrations from a
dated sediment core to infer historical concentra-
tions in lake trout indicate that, historically, the
threshold concentration would have been ex-
ceeded (Cook and Burkhard, 1998). Further-
more, until recently lake trout hatched from
females collected from the Great Lakes suffered
a relatively high incidence of blue-sac disease.
Although it has been reported that this incidence
can be caused by bacterial infections (Symula et
al., 1990), the edematous condition seen is
characteristic of exposure of lake trout to
2,3,7,8-TCDD or structurally similar compounds
(Walker and Peterson, 1994a; Cook et al.,
1997). Because the dose-response relationship
for the dioxin-like compounds in lake trout is so
steep, it is likely that the concentrations of di-
oxin TEQ in the eggs were well above the toxic-
ity threshold for blue-sac syndrome (Guiney et
ng/kg
25,000
20,000
15,000
10,000
5,000
0
LT = lake trout
RT = rainbow trout
20,000
70
500
LTSac
Fry
RTSac
Fry
2,000
RT Swim-up RT Juvenile
Fry
Figure 3-6. LD5Q concentrations for effects of TEQs on
lake trout (redrawn with permission from Walker and
Peterson, 1994a).
3-5
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
al., 1996) in the recent past. Problematic levels
are still reported, where extracts of whole adult
lake trout from Lake Michigan continue to lead to
lethality when injected into rainbow trout eggs in
graded doses (Wright and Tillitt, 1996). The ex-
tract, which contained PCDD, PCDF, and PCB
congeners, caused yolk-sac edema, cardiofacial
deformities, and hemorrhage. All of these symp-
toms have been observed in Great Lakes fish and
can be caused by exposure of fish eggs to TCDD.
In summary, it is not possible to determine the
actual degree to which POPs have affected lake
trout populations in the Great Lakes (Zint et al.,
1995). It is likely that dioxin TEQs, primarily
from dioxin-like PCB congeners, have caused
reproductive impairment of lake trout in the
lower lakes, but not Lake Superior. Declines in
lake trout populations began in Lakes Ontario,
Huron, and Michigan before concentrations of
POPs were high enough to drastically reduce
reproduction. This observation, along with the
fact that "catch per unit effort" generally declines
after populations have declined, indicates that
initially non-contaminant effects were most likely
the cause of the population declines of lake
trout. Also, because populations began to de-
cline before sea lamprey numbers were suffi-
ciently high to cause severe population reduc-
tions, the most likely cause of the decline in lake
trout populations in the lower lakes was over-
exploitation by the commercial fishery. POPs
may have played a significant role in delaying
reestablishment of lake trout in the lower lakes,
but the effects should begin to abate now that
concentrations of these compounds have declined
to near the threshold for mortality of eggs and
fry.
During the 1960s and 1970s, when the pesticide
DDT was being used in the North American
environment, populations of several sensitive bird
species declined as individuals became unable to
successfully incubate eggs because of abnormally
thin shells (Cooke, 1973). The eggshell-thinning
effect of DDT and its potent, stable, metabolite
p,p'-DDE in sensitive species is well known, even
to the lay public. Indeed, the contributions of
DDT to population declines in bird species such
as brown pelicans (Pelecanus occidentalis),
peregrine falcons (Falco peregrin is), and bald
eagles are probably the most famous incidents in
wildlife ecotoxicology. Although many popula-
tions worldwide were adversely affected, some of
the more notable species that suffered cata-
strophic declines in the Great Lakes basin
included the osprey (Pandion halieatus), bald
eagle, and many colonial fish-eating birds such as
herring gulls (Figure 3-7), common and Caspian
terns, and double-crested cormorants (Figure 3-
8). In fact, some of these species were almost
completely extirpated from the Great Lakes
basin. These effects, including declines in popu-
Figure 3-7. Herring gull colony in Lake Michigan.
Photo: John P. Giesy
Figure 3-8. Double-crested cormorant colony, Lake Huron.
Photo: John P. Giesy
3-6
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
lations, have been best documented for colonial,
fish-eating water birds (Gilbertson et al. 1991;
Peakall and Fox, 1987). Although effects were
not restricted to the Great Lakes basin, a num-
ber of species in the Great Lakes experienced
significant population declines (Bowerman et al.,
1995, 1998). Many of these species, such as
the double-crested cormorant, have experienced
dramatic population increases since DDT was
deregistered in the United States and environ-
mental concentrations have declined (Ludwig,
1984; Weseloh and Ewins, 1994).
Figure 3-10. Bald eagle in flight.
Photo: U.S. FWS
There is no question that bald eagle (Figures 3-9,
3-10) populations declined greatly from historical
levels, but the specific reasons for these declines
Figure 3-9. Bald eagle egg in eagle nest with habitat in
background.
Photo: D. Best/U.S. FWS
are less clear (Bowerman et al., 1995). The
numbers of bald eagles in North America de-
clined greatly after World War II (Grier, 1982;
Postupalski, 1985). This decline was particularly
acute in the Great Lakes region (Colborn, 1991).
Habitat changes and killing of adults certainly
played a role in the population dynamics of bald
eagles in the continental United States and Great
Lakes basin. However, the greatest effect on
bald eagle populations was from DDT residues,
specifically the degradation product p,p'-DDE,
which is known to cause eggshell thinning in
eagles (Peakall et al., 1973; Feyk and Giesy,
1998). The effect of DDT residues on bald
eagle reproductive success, like many other rap-
tors, is inversely proportional to the dose of p,p'-
DDE (Figure 3-11). It is clear that this com-
pound exceeded concentrations sufficient to
cause population-level declines in bald eagles of
the Great Lakes basin (Wiemeyer et al., 1984,
1993; Bowerman et al., 1995). Beyond this, it
is impossible to separate the potential effects of
other organochlorine compounds, such as dield-
rin, PCBs, and dioxins, all of which accumulated
in eagles to concentrations that may have con-
tributed to population-level declines (Wiemeyer
et al., 1984, 1993; Giesy et al., 1995;
Bowerman et al., 1998).
In 1976, just after the use of DDT was cancelled
in North America, there were approximately 30
breeding pairs of eagles along the shores of the
Great Lakes and 80 and 100 pairs in the interior
regions of Michigan and Minnesota, respectively
3-7
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
1.2-
to
£ 1.0
"D
ga
'§• 0.8-
O
o
I 0.6
I 0.4
£
0.2-
0.0
y = - 0.0205X + 1.224
/•2 = 0.945
10
20
ng/g
30
40
Figure 3-11. Productivity of bald eagles as a function of
the geometric mean p,p'-DDE concentration (ng/g wet
weight) in the plasma of nestling bald eagles between
1977-93 (Bowerman et al, 1995).
(Figure 3-12). On ceasing the use of DDT in
North America, concentrations of p,p'-DDE in
the environment, particularly in the diets of fish-
eating birds, began to decline. Subsequently,
once the concentrations had declined below the
threshold for population-level effects, populations
of eagles began to increase (Grier, 1982;
Postupalsky, 1985). The number of breeding
pairs has increased steadily since 1976
(Postupalsky, 1985).
Currently, bald eagles nesting along the shoreline
of the Great Lakes do not reproduce as well
as those nesting on inland bodies of water
(Bowerman et al., 1995). Two common
Figure 3-12. Numbers of breeding pairs of bald eagles
along the Great Lakes shorelines and in the interiors of
Michigan and Minnesota for the period 1977 to 1993
(Bowerman et al., 1995).
measures of the reproductive success of bald
eagles are the number of young fledged per
occupied nest, referred to as productivity (com-
pared over the total number of nests in a speci-
fied region or area), and the reproductive success
of each nest (given as the number of young pro-
duced in a specific nest, e.g., 0, 1, 2 chicks).
Maintenance of a stable bald eagle population
requires a productivity of approximately 0.7
chicks/occupied nest/year. A healthy popula-
tion, capable of exporting excess productivity to
colonize other areas, is characterized by a pro-
ductivity of greater than 1.0. Productivities less
than 0.7 are insufficient to replace the loss of
adults (Bowerman et al., 1995). The average
productivity for bald eagles nesting along the
shorelines of the Great Lakes is 0.7, which is just
sufficient to maintain a stable population, but
not to expand. Any expansion of bald eagle
populations along the shoreline of the Great
Lakes is due to immigration from other more
productive areas. The productivities for the
Michigan shoreline on Lakes Michigan and Huron
are 0.53 and 0.25, respectively, which are insuf-
ficient to maintain stable populations, let alone
support any expansion (Figure 3-13). Bald
eagles along rivers with anadromous (fish that
return to inland streams to breed) populations of
Measures of Productivity for Bald Eagle
Bretfffing Areas in Michigan
Great Lakes 9fi
47.3
I^H Anadromous '
No. Fledged Yg./Occupied B.A.
°/o Rate of Success of Occupied B.A.
Michigan
Figure 3-13. Reproductive success of bald eagles in
Michigan. B.A. = Breeding area, the area bald eagles
frequent when they are paired, breeding, and raising
chicks, which may include several nests, only one of
which is used per year (data from Bowerman et al.,
1998).
3-8
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
salmon from the Great Lakes have a very low
productivity of 0.55. The reduced productivities
along the shores of the Great Lakes and anadro-
mous salmon streams may be due to a number
of factors, including exposure to residual concen-
trations of p,p'-DDE, but may also be caused by
exposure to PCBs, PCDDs, and PCDFs or other
compounds (Giesy et al., 1994, Bowerman et
al., 1995). In addition, there may be microcli-
matological effects in some areas and impacts of
low food availability (Dykstra et al., 1998). Al-
though it is impossible to know the exact contri-
bution of each of the POPs to eagle reproductive
impairment, it is likely that current concentra-
tions of POPs such as PCBs (Figure 3-14) in the
Great Lakes are sufficient to cause population-
level effects on some subpopulations of bald
eagles (Bowerman et al., 1995).
Current concentrations of PCDD, PCDF, and
PCBs in both Great Lakes piscivorous birds and
their prey are less than they were in the 1960s
and 1970s. Some bird populations, such as
double-crested cormorants and herring gulls, have
made dramatic recoveries since that time.
Populations of other species, such as common
and Forster's terns, continue to decline. The
concentrations of TEQ in several species appear
to be greater than the threshold for discernible,
population-level effects at several locations
Figure 3-14. Concentrations of PCBs in blood plasma of
bald eagles in Michigan (data from Bowerman et al.,
1991).
around the Great Lakes (see Giesy et al., 1994b,
for a comprehensive review). For instance, sub-
populations of double-crested cormorants and
Caspian terns in Saginaw Bay and Green Bay
continue to display embryo lethality (Figures
3-15 and 3-16) and abnormally high rates of
developmental deformities (Figures 3-17 and
3-18). In general, all of the populations of fish-
eating birds from the Great Lakes are displaying
symptoms of exposure to chlorinated chemicals
at the biochemical level.
PCDDs, PCDFs, and certain structurally similar
PCBs have been demonstrated to cause a syn-
drome referred to as Great Lakes Embryo Mor-
tality Edema and Deformities Syndrome
(GLEMEDS) (Table 3-2). This syndrome, which
Figure 3-15. Cormorant eggs. One died while hatching.
Photo: John P. Giesy
- Double-crested cormorant
individual colonies /1986, 1987, 1988
Y = 0.067(X) + 13.1 (ft = 0.703, p = 0.0003)
50
100 200 300
Dioxin equivalents (pg/g)
Figure 3-16. Correlation between embryo lethality (egg
death) as a function of total dioxin toxicity equivalents in
double-crested cormorant eggs from the Great Lakes
(Giesy et al., 1994a; Tillitt et al., 1992).
3-9
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
Figure 3-17. Cormorant with cross-bill malformation.
Photo: John P. Giesy
is similar to chick edema disease, results in em-
bryo lethality and developmental deformities in
fish-eating birds. Although the degree of expres-
sion of GLEMEDS has decreased as concentra-
tions of PCDDs, PCDFs, and PCBs have de-
clined, certain species in some locations are still
affected. These exposures are still causing le-
thality and deformities in embryos of all of the
populations examined by research groups from
the United States and Canada, including those
from Michigan State University (extensively re-
viewed in Giesy et al., 1994a,b). The observed
effects are greater than those observed in less
contaminated populations not breeding on the
Great Lakes, although these effects are trans-
lated into biologically significant population-level
R2 = 0.99
tfl
1
1
a
"5
Number
14-i
12
10
8
6
4
2
0
( 0 SO 100 150 200 250 300 350 400 450 500
( Dioxin Equivalents (ng/kg, ww)
Figure 3-18. Rates of deformities per thousand double-
crested cormorant embryos for the Great Lakes (Giesy et
al., 1994a). LS-Lake Superior, LM-Lake Michigan, LH-
Lake Huron, GB-Green Bay
• Embryo lethality
• Liver mixed function oxidase (MFO) induction
* Unabsorbed yolk sacs
« Vitamin A depletion
« Porphyria
# Teratogenesis
Source: Gilbertson et al. (1991).
effects only in the more contaminated areas,
such as Saginaw and Green Bays.
As with fish, the results of laboratory and field
studies indicate that the lethality and deformities
(Table 3-3) of embryos of fish-eating birds from
the Great Lakes are caused by the toxic effects
of multiple compounds expressed through the Ah
receptor. The use of TEQ as the measurement
unit also explains the observed effects better
than single measurements of individual com-
pounds (Geisy et al., 1994a). When the current
concentrations of PCBs and PCB-derived TEQs
in the diets of fish-eating birds of the Great
Lakes were compared with NOAEL values for
these species, based on both laboratory and field
studies with these species as well as surrogates,
the hazard quotients and exceedence values were
greater than 1.0 for all of the species in all of the
lakes (Giesy et al., 1994b; 1995). The magni-
tude of the hazard quotient values varies among
species and lakes. Bald eagles are the most
exposed and the most sensitive, whereas cormo-
rants are relatively tolerant of the effects of PCB-
derived TEQs.
In addition to colonial, fish-eating water birds,
several other wildlife populations have been
Table 3-3. Deformities caused by
exposure to TEQs
• Gastroschisis
« Crossed bills
* Clubfoot
« Dwarfed appendages
* Edema/ascites
* Hemorrhaging
• Abnormal feathering
• Abnormal eyes
» Hydrocephaly
• Anencephaly
Source: Giesy et al. (1994a).
3-10
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
reported to be affected by contaminants in Great
Lakes fish. Populations of mustelids, including
mink (Mustela uison) (Figure 3-19) and river
otter (Lutra canadensis), have declined in re-
gions along the Great Lakes or along rivers that
are not blocked by dams, to which fish from the
Great Lakes have access (Giesy et al., 1994c).
It is difficult to conduct a risk assessment for
mink because accurate information on their diets
is limited. A number of researchers have re-
ported that feeding fish from the Great Lakes
has resulted in adverse effects on ranch mink,
and several analyses have been conducted to
examine the effects of contaminant compounds
(Giesy et al., 1994c; Kannan et al., 2000). In
studies feeding Great Lakes fish, mink are simul-
taneously exposed to a number of synthetic,
halogenated compounds, including POPs insecti-
cides. Because the concentrations of many of
these compounds are intercorrelated, it is diffi-
cult to separate their effects and determine
which are most likely to have caused adverse
effects in populations of wild or ranch mink. As
little as 1% Great Lakes fish in the diet of mink
is sufficient to cause adverse effects on survival
and growth of the kits (Restum et al., 1998;
Giesy et al., 1994c); 40% Great Lakes fish in
the diet causes mortality of adult female mink
(Heaton et al., 1995a,b). When adult female
mink were fed 10% Great Lakes fish, the num-
ber of surviving kits was significantly reduced
(Figure 3-20). Historically, when the concentra-
tions of insecticides such as DDTs in the tissue of
Birth 3 Weeks 6 Weeks
! Control miO% Diet D 20% Diet D40% Diet
Figure 3-19. Mink in the wild eating fish.
Photo: J. McDonald/Corbis.com
Figure 3-20. Survival of mink kits as a function of varying
proportions of Great Lakes fish in the maternal diet
(Tillit et al., 1996; Heaton et al., 1995a).
fish from the Great Lakes were higher, it was
concluded that that they were unlikely to be the
cause of the effects observed when fish from the
Great Lakes were fed to ranch mink. The most
likely causes of the observed effects are again
the PCDDs, PCDFs, and PCBs. Although it is
difficult to determine the exact cause of the
observed effects, it is clear that residues present
in fish from the Great Lakes can cause signifi-
cant effects on the survival and reproduction of
mink.
Of all the pollutants to which mink have been
exposed, PCBs seem to have had the greatest
impact. Mink are one of the most sensitive
species to the effects of PCBs. In an attempt to
determine if current concentrations of PCBs
represent a risk to mink, hazard quotients were
calculated assuming that mink ate only Great
Lakes fish in their diet (Heaton et al., 1995a,b).
Hazard quotients for PCBs in fishes from the
Great Lakes ranged from a minimum of 6.4 to a
maximum of 83. Percent allowable consumption
values for feeding Great Lakes fish to mink were
all less than 100%, and ranged from as little as
1.2% to as much as 19%, depending on the fish
species and its source. Thus, there is no combi-
nation of Great Lakes fish that would result in a
nonhazardous diet to mink. The average allow-
able fish content in the mink diet for all of the
Great Lakes fish was 7.5% (Giesy et al., 1994c).
The onset time and duration of exposure of mink
to salmon is also problematic, such that mink
3-11
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
could be eating large quantities of salmon for
several months during sensitive reproductive
periods. The late fall and early winter is a criti-
cal period for exposure to toxicants, when mink
are mating and the females are pregnant. Dur-
ing this period, several species of anadromous
salmonid fish migrate into Michigan rivers to
spawn. The coho and chinook salmon die soon
after spawning and are deposited on the shores
of the river. With the onset of cold weather, the
carcasses of the salmon can persist along the
shore for a prolonged period of time. In this
way, these fish could be a substantial source of
contaminants to mink. For instance, using aver-
age concentrations of TEQs in fish from the
Great Lakes, HQ values were all greater than
1.0, indicating some degree of risk to mink
(Table 3-4). Most of the TEQs were contributed
by PCBs.
From a time perspective, consuming chinook
salmon for as little as 2 weeks could deliver the
Table 3-4. Hazard quotients for consumption of TEQ-
containing Great Lakes fishes by mink
Common carp 47
Chinook salmon 11
Alewife 5.8
Northern pike 30
Calculated from information contained in Heaton et al. (1995a,b)
and Tillitt et al. (1996), and unpublished data on concentrations of
residues in fish tissue, J.P. Giesy.
annual dose to mink that would be expected to
affect reproduction (Giesy et al., 1994c).
All of the compounds listed in the Stockholm
Convention on POPs have been identified in
fish and wildlife of the North American Great
Lakes, even though some of these com-
pounds, such as toxaphene, were never used
in significant quantities in the region. This
finding indicates that the source of some
POPs in the Great Lakes ecosystem is long-
range atmospheric transport.
Concentrations of POPs in Great Lakes fish
have decreased significantly, approximately
25-fold, since the use of these compounds
ceased within the Great Lakes basin.
Concentrations of the key POPs, such as p,p'-
DDE and PCBs, in Great Lakes wildlife are
currently either not declining or declining only
slowly. POPs declines in Great Lakes waters
have also slowed, reflecting a complex inter-
relationship among loss to sediments, tem-
perature-dependent fluxes to and from the
atmosphere, and continuing inputs from urban
and other sources, local and remote (Miller et
al., 2001; Swackhamer et al., 1999; Simcik
et al., 1999). Further input reductions of
POPs and the continued recovery of wildlife
populations depends, in part, on controlling
long-range atmospheric transport of POPs
from other parts of the world (US EPA, 2000).
Historically, several POPs accumulated to
sufficient concentrations to cause adverse
effects on fish and wildlife in the Great Lakes.
The degradation product of the organochlo-
rine insecticide DDT, p,p'-DDE, which causes
eggshell thinning in raptors such as peregrine
falcons, ospreys, and bald eagles, resulted in
decreases in populations of these species to
the point where they were almost completely
extirpated from the Great Lakes basin.
PCDDs, PCDFs, and certain structurally simi-
lar PCBs caused a syndrome referred to as
GLEMEDS in colonial fish-eating water birds
of the Great Lakes. This syndrome, which is
similar to chick edema disease, results in
embryo lethality and developmental deformi-
ties in birds. The degree of expression of
GLEMEDS has decreased as concentrations of
PCDDs, PCDFs, and PCBs have declined, but
certain species in some locations are still
affected.
Concentrations of POPs residues, primarily
PCDD, PCDF, and PCBs, in fish are still suffi-
cient to cause mortality in adult mink and
3-12
-------
POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
severely reduce reproduction at as little as 1%
Great Lakes fish in the diet.
Historically, concentrations of dioxin-TEQs,
primarily from PCBs, were sufficient to cause
blue-sac syndrome in sensitive fish species
such as lake trout, and probably contributed to
their population declines and restricted recov-
ery. Currently, concentrations have decreased
to a point where the incidence of blue-sac
syndrome is rare.
At present, bald eagles nesting along the
shorelines of the Great Lakes and along
anadromous, accessible rivers have diminished
reproductive capacity compared with those
living at inland sites.
Even though concentrations of many of the
POPs have decreased in Great Lakes wildlife
subsequent to restriction of their use in the
Great Lakes basin, some species of wildlife in
some locations continue to be affected.
Failure to control sources of POPs outside the
Great Lakes basin will limit the ability of the
Great Lakes wildlife to recover.
The Great Lakes experience demonstrates that
it is possible to sufficiently contaminate environ-
ments with residues to cause adverse effects.
The experience in the Great Lakes is also one
of hope, because controls on the production
and release of POPs can result in reduced
environmental concentrations and wildlife
recovery.
Bowerman WW, Best DA, Evans ED, Postupulski S,
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Bowerman WW, Giesy JP, Best DA, Kramer VJ. 1995.
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Colborn T. 1991. Epidemiology of Great Lakes eagles.
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Cook PM, Zabel EW, Peterson RE. 1997. The TCDD
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Cooke AS. 1973. Shell thinning in avian eggs by envi-
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Giesy JP, Ludwig JP, Tillitt DE. 1994b. Dioxins,
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Giesy JP, Verbrugge DA, Othout RA, Bowerman WW,
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DA, Tillitt DE. 1995. Contaminants in Fishes From
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Giesy JP, Snyder EM. 1998. Xenobiotic Modulation of
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Gilbertson M, Kubiak TJ, Ludwig JP, Fox G. 1991.
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Glassmeyer ST, De Vault DS, Hites RA. 2000. Rates at
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1855.
Grier JW. 1982. Ban of DDT and subsequent recovery
of reproduction in bald eagles. Science 218:1232-1235.
Guiney PD, Cook PM, Casselman JM, Fitzsimmons JD,
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Heaton SN, Bursian SJ, Giesy JP, Tillitt DE, Render JA,
Jones PD, Verbrugge DA, Kubiak TJ, Aulerich RJ.
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Heaton SN, Bursian SJ, Giesy JP, Tillitt DE, Render JA,
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Kannan K, Blankenship AL, Jones PD, Giesy JP. 2000.
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Leatherland JF 1993. Field observations on reproduc-
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Ludwig JP. 1984. Decline, resurgence and population
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cormorants. Jack-Pine Warbler 62:91-102.
Mac MJ, Edsall CC, Seeyle JG. 1985. Survival of lake
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Peakall DB, Lincer JL, Risebrough RW, Pritchard JB,
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Comp Gen Pharmacol 4:305-314.
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POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
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Postupalsky S. 1985. The bald eagles return. Nat Hist
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Shanks KE, McDonald JG, Hites RA. 1999. Are pulp
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sphere. Environ Sci Technol 33:1991-1995.
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Swackhamer DL, Pearson RF, Schottler SP. 1998.
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POPs Residues and their Effects on Fish and Wildlife of the Great Lakes
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3-16
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Animals often act as sentinels for human health
(NRC, 1991). This is especially true for humans
who, through cultural tradition or free choice, live
closer to nature and have lives intimately linked to
the subsistence food sources in their local region.
In turn, these susceptible populations can act as
sentinels to the mainstream U.S. population, for
whom the complexity of modern society and di-
verse dietary sources diffuse connections and make
causal linkages to health outcomes difficult to iso-
late. Thus, the early findings of persistent organic
pollutant (POPs) exposures and adverse effects on
wildlife reproduction, development, and survival in
the Great Lakes and other water bodies stimulated
research to determine if similar effects were occur-
ring in human populations. In particular, efforts
centered on the families of sport fishers and Native
Americans known to consume large amounts of
Great Lakes fish. This chapter summarizes this
research, providing information on human expo-
sures, epidemiological results, and regulatory con-
siderations for human populations in the Great
Lakes region. Although the discussion is centered
on the Great Lakes, its message relates to all com-
munities in the United States exposed to POPs
pollution.
The chapter is based on epidemiological informa-
tion: the study of disease in human populations.
Epidemiological research is a difficult endeavor,
reflecting the complexity of the species under
investigation. This complexity affects the multiple
exposures and endpoints experienced by humans
and the variations, patterns, and linkages in expo-
sures, as well as the statistical methods necessary to
tease these apart. Laboratory confirmation of low-
level toxicological results in humans is not usually
an option because of ethical considerations. As a
result, when interpreting data consideration must
be given to the inherent difficulties in analyzing
potential effects from low-level exposures. For
instance, an adverse human health impact may be
difficult to demonstrate because the number of
people affected is small relative to the statistical
power of the study to isolate this effect. For POPs,
the control group in a study may also be exposed,
albeit to a lesser degree, leading to a situation
where both exposed and control groups may be
exhibiting adverse effects and there appears to be
no difference between the two. Misclassification of
exposure, a common difficulty, also tends to diffuse
results and weaken findings of effects.
From another perspective, there may be no ad-
verse effects from a POPs exposure and yet statisti-
Paper company waste disposal basin in 1970: A source of
pollutants to the Great Lakes.
Photo: Minnesota Sea Grant, March 1970
4-7
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POPs in the Great Lakes: Human Health Considerations
cally significant differences are found between
control and exposed groups. This can be the result
of such simple factors as performing multiple tests,
some of which will eventually appear "abnormal"
by chance alone because of the common p < 0.05
(1 in 20) statistical significance value. More difficult
to isolate are the effects of confounding and bias,
where the control and exposed groups become
unbalanced through study design limitations. For
instance, lifestyle differences between sport fishers
in the Great Lakes and the general population need
to be considered before assigning health outcomes
solely to dietary differences in POPs intake. For a
more detailed analysis of these epidemiological data
and considerations, see De Rosa et al. (1999) and
Johnson et al. (1998).
The first human exposure study of POPs in the
Great Lakes was the 1974 study of polychlorinated
biphenyl (PCB) intake from sport fish consumption
(Michigan Sports Fishermen Cohort; Humphrey,
1976). Sport fish eaters were found to consume
on average 14.5 kg (32 pounds) of fish per year,
some eating as much as 119 kg (262 pounds) per
year. During the 1970s, this average was approxi-
mately five times the national per capita fish con-
sumption rate commonly used in risk estimates.
Individuals who regularly ate 11 kg (24 Ibs) per year
or more of Great Lakes fish had higher (p < 0.001)
serum levels of PCBs than individuals who seldom
or never ate such fish. The study was repeated in
1982, again indicating that individuals in the upper
range of fish consumption had serum PCB levels
approximately four times greater than unexposed
individuals. These studies identified a positive
correlation between human intake of toxic pollut-
ants and the consumption of Great Lakes fish
(Humphrey, 1976, 1988a,b, 1989).
A similar assessment of body burden levels of PCBs
and DDE was undertaken in the Wisconsin Sports
Fish-Consumers Cohort Study (Fiore et al., 1989;
Sonzogni et al., 1991). Using new technology for
analyzing toxic chemicals in human blood, the
investigators were the first to determine PCB-
specific congeners in Great Lakes sport anglers.
They determined that the congeners most fre-
quently identified in human sera were also the most
abundant congeners in the tissues of a variety of
Wisconsin fish (Maack and Sonzogni, 1988). Body
burden levels of PCB congeners and DDE were
significantly correlated with the number of sport
fish meals consumed.
Both of these early studies demonstrated that hu-
man populations can be exposed to POPs through
consumption of fish. Multimedia analyses support
this finding, showing that most human exposure to
chlorinated organic compounds (80-90%) comes
from the food pathway (Figure 4-1). A lesser
amount (5-10%) comes from air, and very small
amounts (less than 1%) come from water (Birming-
ham et al., 1989; Newhook, 1988). Recent data
indicate that fish consumption appears to be a
major pathway for exposure to POPs chemicals,
especially for compounds such as PCBs and diox-
ins (Fitzgerald et al., 1996; Schaum et al., 1999).
Recreational fishers and the Great Lakes.
Photo: ATSDR
Cooperation between Canada and the United
States on the Great Lakes is managed through the
International Joint Commission (IJC), established
under the 1909 Boundary Waters Treaty. Among
the IJC's mandates is the responsibility for protect-
ing the lakes and river systems along the border for
the benefit of citizens and future generations. In
1985, the IJC identified 11 of the most persistent
and widespread toxic substances as critical Great
4-2
-------
POPs in the Great Lakes: Human Health Considerations
Great Lakes Food Web
Figure 4-1. The Great Lakes food web. Heavy metals and
many synthetic chemicals are absorbed by organisms and
biaccumulate, with concentrations reaching toxic levels if
exposure is great enough. The concentration is magnified
at each step of the food web (Hicks et a/., 1996).
Lakes pollutants: PCBs, DDT, dieldrin, toxaphene,
mirex, methylmercury, benzo[a]pyrene (a member
of a class of substances known as polycyclic aro-
matic hydrocarbons [PAHs]), hexachlorobenzene
(HCB), polychlorinated dibenzo-p-dioxins and
dibenzofurans, and alkylated lead (IJC, 1983).
Eight of these pollutants are on the initial list for
the Stockholm Convention, with the remaining
four global POPs incorporated under subsequent
Great Lakes binational agreements (http://
www.epa.gov/glnpo/bns).
Forty-two geographic locations in the U.S. and
Canadian Great Lakes basin have been identified
by the IJC as "Areas of Concern" because of high
concentrations of these toxic pollutants (National
Health and Welfare Canada, 1991) (Figure 4-2).
Of these 42 locations, 31 are located within the
boundaries of the United States (Hicks, 1996).
Beyond the substances and locations prioritized by
the IJC, many more commercial and industrial
compounds (-30,000) are produced or used in the
Great Lakes basin, about 1,000 of which have
been identified in the Great Lakes environment.
In 1990, the U.S. Congress amended the Great
Lakes Critical Programs Act to investigate human
health concerns and pollutants in the Great Lakes.
In response, the Agency for Toxic Substances and
Disease Registry's (ATSDR) Great Lakes Human
Health Effects Research Program (GLHHERP) was
initiated in 1992. This program is designed to
characterize exposure to toxic chemicals from
consumption of Great Lakes fish and to investigate
the potential for short- and long-term adverse
health effects. The research program focuses on
the initial 11 critical Great Lakes pollutants identi-
fied by the IJC, as well as other chemicals of con-
L*ktS*f»fior
1. Penii«al* Hajbour
2. )K.k[»li Bay
9. Meaarninee River
la
Si. Lank B»y Tirnr
Track Ult
11, Sdeboypn River
12. Milwaukee EKllary
13. W«Bket*u Harbor
14. Grand Calumet
Rwerflrtdittna Harbor
Cud
15. Kdmuoa Rim
16. Mu>kc,t,,n Ute
17. TOM Lute
L*k Hurra
1$. Sagiitaw Rh*r^a|iB**
B.,
19. CoBingxooJ Hlrtrair
20. Sew™ Sound
21. Spanish River Mmati
22. Onion Riwt
23. Rou^ River
24. R!v«r Mkto
2$, MJUTHM Rhcr
28. B«*Rm»
27. O^tfeog* River
m AlbUball Rhcr
29 Frtique Isfc B»)
30. Wheuley lUfbra.r
UWO.Urfc,
31. Buffalo knei
31 t&m Mite Cte«k
33. Rodie$l«r EnsbayERGtii
34. Oswega River
35. Bay of Quinte
36. P« Hope
37. Metro Toronto
•»> Hamilton Hubotr
X, SI Mam Rivt,
40. St. etnir River
41, Detroit River
42. N«pn River
43. St. Lawrence River
Figure 4-2. IJC areas of concern in the Great Lakes Basin
(Great Lakes Fishery Commission, 1993). (#19 Calling-
wood Harbor has been delisted as an area of concern.)
4-3
-------
POPs in the Great Lakes: Human Health Considerations
cern in the Great Lakes basin. The program has
identified several sensitive human health endpoints
for study, including behavioral, reproductive, devel-
opmental, neurologic, endocrinologic, and immu-
nologic measures. ATSDR's Great Lakes research
further identified several human populations that
may be at particular risk because of higher expo-
sures to Great Lakes pollutants via fish consump-
tion (Table 4-1). Predisposition to toxic injury in
these populations can be due to behavior (e.g.,
degree of contaminated fish consumption), nutri-
tional status, physiology (e.g., developing fetuses),
or other factors. These communities of concern
include subsistence fish anglers, Native Americans,
pregnant women, fetuses, nursing infants of moth-
ers who consume contaminated Great Lakes sport
fish, young children, the elderly, the urban poor,
and those with compromised immune function.
Contemporary data continue to support the
association between the consumption of contami-
nated Great Lakes fish and elevated body burdens
of POPs, summarized by the following findings
(Table 4-2):
S Communities of concern in the Great Lakes
basin are still exposed to POPs, including
PCBs, polychlorinated dibenzo-p-dioxins and
furans, and chlorinated pesticides (e.g., DDT)
(Hanrahan et al., 1999; Stewart et al., 1999;
Schantz et al., 1999; Johnson et al., 1998;
Anderson et al., 1998; Dellinger et al., 1996;
Fitzgerald et al., 1996; Lonky et al., 1996;
Schantz et al., 1996; and Humphrey et al.,
2000).
Table 4-1. Human populations at increased risk
- Native Americans
Sport anglers
Elderly
Pregnant women
Fetuses
Nursing infants
Women and men of reproductive age
Immunologically compromised persons
Levels of some contaminants in Great Lakes
sport fish are above the advisory limits set by
the state and federal governments (Dellinger
etal., 1996).
Sport fish eaters consume on average two to
three times more fish than the estimate of 6.5
g/day for the general U.S. population
(Courval et al., 1996, 1999; Fitzgerald et al.,
1996, 1999; Schantz etal., 1996, 1999;
Anderson et al., 1998; Hanrahan et al.,
1999; He et al., 2001). In one survey in
Michigan, Great Lakes sport fish consumers
reported eating on average 42 g/day (Michi-
gan Department of Environmental Quality,
1996). The reported weight of fish consumed
declined from the early 1970s to 1990s (He
etal., 2001).
Consumption of Great Lakes fish appears to
be the major pathway of exposure for some
POPs (Fitzgerald et al., 1996, 1999; Stewart
et al., 1999). Men eat more fish than do
women, both genders eating Great Lakes fish
during most of their reproductive years
(Courval et al., 1996; Fitzgerald et al., 1996,
1999; Lonky et al., 1996; Waller et al.,
1996; Hanrahan et al., 1999).
Body burden levels for some of the POPs are
two to eight times higher than those of the
general U.S. population (Anderson et al.,
1998; Hanrahan et al., 1999; Schantz et al.,
1996, 1999; He et al., 2001). A significant
trend of increasing body burden is associated
with increased fish consumption (Fitzgerald et
al., 1996, 1999; Falk et al., 1999; Hanrahan
etal., 1999).
Although background levels of PCBs appear
to have declined in Great Lakes residents by
the early 1990s, serum PCB levels among
consumers of sport-caught Great Lakes fish
did not significantly decrease (He et al.,
2001).
Epidemiological studies of Great Lakes populations
have centered principally on reproductive effects
and neurobehavioral/cognitive impacts on children.
4-4
-------
POPs in the Great Lakes: Human Health Considerations
Population
Table 4-2. Exposure studies in human populations
Findings
Reference
Lake Michigan fisheaters
cohort
PCB levels in breast milk and maternal serum
correlate with consumption of contaminated fish.
Humphrey,
1983
Native Americans
(Mohawk) in New York
State
Mean serum PCB level in men of 5.4 parts ppb (max.
31.7 ppb), versus 2 ppb in the general population
(Jensen, 1989). Serum PCB levels were positively
related to the number of fish meals consumed per
year and increasing age.
Fitzgerald et al.,
1996
Elderly cohort of Lake
Michigan sport anglers
PCBs and DDE levels were significantly higher
in high fisheaters. High fisheaters presented
disproportionately higher body burden levels of PCBs
and DDE than low fisheaters in each age group, i.e.,
50-59, 60-69.
Schantz et al.,
1996
Pregnant women who
consumed Lake Ontario
fish
Women in the high fish consumption group ate an
average of 2.3 salmon or trout meals per month for
an average of 16 years.
Lonky et al., 1996
Pregnant African-
American women who
consumed Lake Michigan
fish
Women were exposed to POPs via fish consumption
during most of their reproductive years. Seventy-five
percent were less than 26 years of age and consumed
lake fish for more than 15 years.
Waller et al., 1996
Reproductive-age (18-34)
Lake Michigan sport
anglers
Approximately 50% ate 1-12 sport-caught meals in
the past year, and 20% consumed 13-24 meals. Fish
consumption was greater in males than females, with
some males consuming 49 or more fish meals per
year.
Courval et al.,
1996
Charter boat captains,
their spouses, and Great
Lakes anglers
Serum levels of dioxins, furans, and coplanar PCBs
vary by gender. Fish species consumed predicted
coplanar PCBs and furan body burden levels, but
not dioxin.
Falk et al., 1999
On the basis of these and similar studies, the Na-
tional Research Council (1999) concluded that:
In humans, results of cognitive and
neurobehavioral studies of mother-infant
cohorts accidentally exposed to high concen-
trations of PCBs and PCDFs and of mother-
infant cohorts eating contaminated fish and
other food products containing mixtures of
PCBs, dioxin, and pesticides (such as DDE,
dieldrin, and lindane) provide evidence that
prenatal exposure to these HAAs [hormonally
active agents] can affect the developing ner-
vous system.
Many of the studies on which this conclusion is
based originated from Great Lakes epidemiological
research and are summarized below.
In a cross-sectional mail survey of reproductive-age
Michigan licensed anglers and their partners,
Courval et al. (1999) reported a modest association
4-5
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POPs in the Great Lakes: Human Health Considerations
in men between sport-caught fish consumption and
the risk of conception failure after trying for at least
12 months. The authors examined the association
between exposure and effects by calculating odds
ratios, the odds of illness among the exposed
group divided by the odds of illness in an unex-
posed group. On the basis of answers to question-
naires, 15% of couples had reported conception
failure. Among men, the unadjusted odds ratios
(ORs) for conception failure were 1.2, 1.3, and 2.0
across the three increasing levels of sport-caught
fish consumption compared to no consumption
(trend test p = 0.06). Adjusting for a number of
variables that may affect study results, i.e., age,
region of Michigan, smoking, and alcohol con-
sumption, the ORs were 1.4, 1.8, and 2.8, respec-
tively. For women, the unadjusted ORs for con-
ception were 0.9, 1.0, and 1.4 with increasing fish
consumption (trend test p = 0.35). When the
same covariates and partner's sport-caught fish
consumption were included in the model for con-
ception failure in women, the ORs became 0.8,
0.8, and 1.0, respectively, indicating no increased
risk from female exposure.
A series of studies on reproductive health has been
performed on a cohort of New York State anglers
and their spouses. In this cohort, questionnaires
provided data on each person's species-specific fish
consumption pattern, medical and reproductive
histories, sociodemographic characteristics, and
other lifestyle behaviors. Individual fish consump-
tion at the time of enrollment in this study was
characterized by self-reported duration and fre-
quency, and used to calculate a PCB exposure
index. Health outcomes were assessed through a
combination of questionnaires and birth certifi-
cates. Multiple regression statistical analyses were
carried out to control for identified variables. Find-
ings from this cohort include the following:
§ Mendola et al. (1995) reported no significant
relationship between estimated low-to-moder-
ate PCB intake from Great Lakes fish (up to 7
mg/lifetime) and the risk of clinically recog-
nized spontaneous fetal death.
§ Mendola et al. (1997) identified significant
menstrual cycle length reductions with con-
sumption of more than one fish meal per
month (1.11 days). Women who consumed
contaminated fish for 7 or more years also
had shorter cycles (-0.63 days). The results
were consistent with measures of frequency of
consumption and the index of lifetime PCB
exposure having a stronger relationship with
menstrual cycle length than the number of
years of fish consumption.
Buck et al. (1997) reported no adverse asso-
ciation between the duration of consumption
of contaminated fish from Lake Ontario and
time-to-pregnancy.
Buck et al. (2000) reported that maternal, but
not paternal, consumption of fish from Lake
Ontario may reduce fecundability (ability to
conceive) among couples attempting preg-
nancy.
Of the epidemiological studies of POPs exposures,
none is more central than the Lake Michigan Ma-
ternal/Infant Cohort Study (Fein et al. 1984;
Jacobson et al. 1985, 1990a,b). This study re-
ported both developmental disorders and cognitive
deficits in the offspring of mothers who were ex-
posed to PCBs via fish consumption for at least 6
years before and during pregnancy. Developmen-
tal effects included a statistically significant decrease
in gestational age (by 4.9 days), birth weight (by
160 to 190 g), and head circumference (by 0.6
cm). Decreased weight and neurological effects
were still evident compared with the control pop-
ulation at 5 and 7 months post-term (Jacobson
and Jacobson, 1988; Jacobson et al., 1985).
Neurobehavioral deficits observed in babies in-
cluded greater inclination to startle; poorer motor
reflex and neuromuscular function; depressed re-
sponsiveness, as evidenced by a greater number of
hypoactive reflexes; impaired visual recognition;
and poor short-term memory at 7 months of age.
At 4 years following birth, these deficits were still
evident in weight gain, depressed responsiveness,
and reduced performance on the visual recogni-
tion-memory test, one of the best validated tests for
the assessment of human cognitive function
(Jacobson et al., 1990a,b).
4-6
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POPs in the Great Lakes: Human Health Considerations
Although these data provide substantial evidence of
in utero effects from PCBs, some significant ques-
tions were raised regarding causality because of
recognized limitations in the studies. These in-
cluded loss of study participants over time, a non-
random sampling technique for the selection of the
study population, limited statistical power because
of the size of the control group, and analysis only
of total PCBs. Also, the standards used (Aroclor
1016 and 1260) as references to quantify total
PCBs accounted for only a small portion of the
PCB congeners detected (Swain, 1991). There-
fore, the analytical methods used to measure PCB
levels may not have been appropriate. Moreover,
many potential confounding variables have been
identified, including exposure to other chemical
contaminants and the mothers' health status at the
time of the study. Nev-
ertheless, a subsequent
retrospective analysis by
Swain (1991) found that
the relationship between
PCB exposure and
transplacental passage
was strongly affirmed,
and the relationship
between PCB exposure
and developmental
effects and cognitive
deficits was affirmed
with reasonable cer-
tainty.
Neurobehavioral testing of a child.
Photo: ATSDR
In a followup examina-
tion of 212 children from the Lake Michigan Ma-
ternal/Infant Cohort Study, the
neurodevelopmental deficits assessed in infancy
and early childhood were found to persist at age 11
(Jacobson and Jacobson, 1996). The study results
indicated that the most highly exposed children,
those with prenatal exposures equivalent to at least
1.25 |ig/g in maternal milk, 4.7 ng/mL in cord
blood, or 9.7 ng/mL in maternal serum
-$ Were three times as likely to have low average
IQ scores (p < 0.001)
•&- Were twice as likely to be at least 2 years
behind in reading comprehension
•$• Had poorer short- and long-term memory
•;?i- Had difficulty paying attention.
The authors concluded that these intellectual im-
pairments were attributable to in utero exposure to
PCBs, and that concentrations of PCBs in mater-
nal serum and milk at delivery were slightly higher
than in the general U.S. population.
The initial findings of the Lake Michigan Maternal/
Infant Cohort Study have now been replicated in
independent cohort analyses. Similar results were
seen in the Oswego Newborn and Infant study, a
prospective longitudinal cohort study examining
behavioral effects in
newborns, infants, and
children exposed pre-
and postnatally to envi-
ronmental toxicants.
Lonky et al. (1996) found
that maternal exposure
to Lake Ontario fish
contaminants (e.g.,
PCBs) was associated
with neurobehavioral
deficits when assessed
shortly after birth. A
total of 559 newborns of
women who had high
exposure, low exposure,
or no exposure to Lake
Ontario fish were examined using the Neonatal
Behavioral Assessment Scale (NBAS) 12-24 hours
after birth and again at 25-48 hours after birth.
Newborns of high-fish-consuming mothers exhib-
ited the following deficits:
-& A greater number of abnormal reflexes
(p < 0.001)
%• Less mature autonomic responses (p < 0.001)
•&- Less attention to visual and auditory stimuli in
comparison to newborns of low- or no-fish-
consuming mothers (p < 0.01)
4-7
-------
POPs in the Great Lakes: Human Health Considerations
These results indicate that newborns of mothers
who consumed 2.3 salmon or trout meals per
month scored more poorly on the NBAS than
newborns from the low-exposure or control
groups. These results represented the first replica-
tion and extension of the neonatal results of the
Lake Michigan Maternal/Infant Cohort study by
Jacobson et al. (1984).
Further analysis of the Oswego data on newborns
revealed significant relationships between cord
blood concentrations of the most highly chlorinated
PCBs and performance impairment on the NBAS
habituation and autonomic tests. No significant
relationship was found between PCBs of lesser
chlorination, DDE, hexachlorobenzene, mirex,
lead, or mercury on any NBAS performance test
(Stewart et al., 2000). The relationship between
prenatal exposure to PCBs and performance on
the Pagan Test of Infant Intelligence (FTII) was also
assessed in the Oswego infants at 6 months and
again at 12 months of age. The results indicated a
significant relationship between exposure to PCBs
and poor performance on the FTII. No significant
relationship was found between exposure to DDE
or methylmercury on any tests of the FTII (Darvill
etal.,2000).
Studies of the impact of POPs, particularly PCBs,
on human neurobehavioral development are not
limited to the Great Lakes region of the United
States and have been performed in other regions
of the United States and abroad. In the early
1980s, the North Carolina Breast Milk and For-
mula Project was conducted with more than 800
mother-infant pairs who were exposed to back-
ground levels of PCBs (Rogan and Gladen, 1985;
Rogan et al., 1986; Rogan and Gladen, 1991).
When the North Carolina children were tested after
birth, children of mothers with higher PCB concen-
trations in their breast milk exhibited the same
behavioral deficits that were characteristic of the
children studied in the Lake Michigan Maternal/
Infant Cohort and the newborns of the Oswego
Newborn and Infant Study. However, at 3 years of
age the behavioral deficits were no longer detect-
able in the children from the North Carolina study.
In an occupational study of women exposed to
PCBs during the manufacture of capacitors in New
York State, decreased gestational age and depres-
sion of weight at birth were associated with PCB
exposure (Taylor et al., 1989).
Internationally, a series of studies in Europe are
investigating the effects of exposure to PCBs and
polychlorinated dioxins and furans on neurological
development in the developing fetus and newborn
(Huisman et al., 1995). These studies have linked
high maternal levels of PCBs, PCDDs, and PCDFs
with reduced neonatal neurological performance.
The data also indicate that high in utero exposure
to PCBs (measured in maternal serum) is associated
with lower psychomotor scores at 3 months of age
(Koopman-Esseboom et al., 1996) and with poorer
cognitive functioning in preschool children at 42
months of age (Patandin et al., 1999). In another
European mother-infant cohort, PCBs in maternal
milk were associated with decreased performance
on the Bayley II mental development index at 7
months, but not with other tests of neurotoxicity
(e.g., FTII) or when using serum PCB concentra-
tion measures (Winneke et al., 1998).
Neurobehavioral changes have also been demon-
strated in monkey and rat offspring following low
perinatal doses of dioxin (Schantz and Bowman,
1989; Markowski et al., 2001) and PCBs (Rice,
1999; Schantz et al., 1989; Levin et al., 1988).
Beyond the developmental neurobehavioral find-
ings reported above, additional studies have been
conducted on Great Lakes fish consumers across
different age groups and different health endpoints.
These include the following:
$ The effects of POPs on the immune system
have been investigated in breast-fed infants
whose mothers consumed contaminated Great
Lakes fish. Maternal serum PCB levels during
pregnancy were positively associated with the
number and type of infectious illnesses occur-
ring in infants during the first 4 months of life
(Smith, 1984; Humphrey, 1988b). The inci-
4-t
-------
POPs in the Great Lakes: Human Health Considerations
dence of infections has also been found to
correlate with the highest rate of fish con-
sumption (at least three times per month for 3
years) and with cumulative lifetime fish con-
sumption (Swain, 1991).
In an older population of sport anglers, 50-90
years of age, fine motor function skills were
assessed to determine the effects of exposure
to PCBs and DDE. This population consisted
of two groups: (a) high fisheaters who had
consumed 24 pounds or more of Great Lakes
sport-caught fish annually for more than 15
years, and (b) low (or non-fisheaters) who
consumed less than 6 pounds annually. The
study demonstrated that serum levels of PCBs
and DDE were highly correlated, and both
were significantly higher in high fisheaters
than in low fisheaters. The mean serum PCB
concentrations for low versus high fisheaters
were 6 ppb and 16 ppb, and the maximum
values were 26 ppb and 75 ppb, respectively.
The mean serum DDE concentrations for low
versus high fisheaters were 7.3 and 15.9 ppb,
with maximum values of 33 and 145 ppb,
respectively. In the cross-sectional data analy-
sis, the authors concluded that PCB and DDE
exposure from consumption of Great Lakes
fish did not impair fine motor function
(Schantz et al., 1996). The study also in-
cluded a longitudinal component, where
changes in individual scores for motor func-
tion over time were postulated to be a more
sensitive indicator of exposure-related effects
(Schantz etal., 1999). Recently published
results of this longitudinal component re-
ported that exposure to PCBs, but not DDE,
was associated with lower scores on several
measures of memory and learning in this older
population of fish-eaters, but not on executive
visual-spatial or motor function endpoints
(Schantz etal., 2001).
Commercial fishing on the Great Lakes, Duluth,
Minnesota.
Photo: Minnesota Sea Grant
States, U.S. territories, and Native American tribes
issue food consumption advisories in order to pro-
tect residents from the health risks associated with
contaminated noncommercially caught fish and
wildlife. These advisories, primarily for fish con-
sumption, inform the public on which species to
avoid or limit eating because of elevated levels of
pollutants. The advisories apply primarily to non-
commercial fish and shellfish obtained through
sport, recreation, and subsistence activities. Each
advisory is different: it may recommend no or
limited consumption; be targeted to everyone or
limited to women and/or children; or may apply to
certain species or sizes of fish. The fish advisories
are submitted annually to EPA and compiled into a
national listing (www.epa.gov/ost/fish).
Fish consumption advisories in the United States
exist for a total of 38 chemical contaminants, but
most advisories involve 5 primary pollutants: mer-
cury, PCBs, dioxin, DDT, and chlordane. Four of
these five pollutants are under the Stockholm Con-
vention. The fifth, mercury, is generally emitted to
the environment as a nonorganic metal, and is
currently slated for a global risk assessment review
by the United Nations Environment Programme.
The number of advisories in the United States
reported in 2000 (2,838) represents a 7% increase
from the number reported in 1999 (2,651) and a
124% increase from the number issued since 1993
4-9
-------
POPs in the Great Lakes: Human Health Considerations
(1,266) (U.S. EPA, 2001). The national survey
indicates that 100% of the Great Lakes and their
connecting waters, and 71% of the coastal water-
ways, were under advisory in 2000 (Table 4-3).
The total number of advisories increased for mer-
cury, PCBs, dioxins, and DDT, although often the
increased number of advisories is considered to
represent better monitoring of fish contamination
rather than increased pollution (U.S. EPA, 2001).
Advisories for PCBs (see Figure 4-3) increased 3%
from 1999 to 2000, from 703 to 726, and in-
creased 128% from 1993 to 2000 (319 to 726).
To date, 75% of the 726 PCB advisories in effect
have been issued by 9 states, 8 of which are Great
Lakes states (U.S. EPA, 2001).
The issuance of fish advisories is not a solution to
POPs pollution, but rather a protective measure
until pollutant reductions to safe levels can be
achieved. Indeed, sociobehavioral and demo-
graphic data from the Great Lakes region reveal
substantial nonadherence to fish advisories for a
variety of reasons, further emphasizing the need
for POPs pollution prevention at the source rather
than relying on dietary pathway advisories.
-?;• A recent survey of adult residents of the eight
Great Lakes states estimated that 4.7 million
people consumed Great Lakes sport fish in a
given year, 43.9% of whom were women
(Tildenetal., 1997).
•&- Knowledge of, and adherence to, health advi-
sories for Great Lakes sport-caught fish vary
across different genders and populations, e.g.,
men compared with women, whites compared
Table 4-3. Fish advisories issued for the Great Lakes
Great Lakes PCBs Dioxins Mercury Chlordane
Lake Superior • • • •
Lake Michigan • • • •
Lake Huron • • •
Lake Erie • •
Lake Ontario • •
Source: U.S. EPA (2001).
Figure 4-3. Fish most affected by PCB advisories: lake
trout, coho salmon, and carp.
Credit: The ABC's of PCBs, University of Wisconsin Sea Grant Institute
with Native Americans (Fitzgerald et al.,
1996, 1999; Waller et al., 1996; Tilden et al.,
1997).
i? 50% of survey respondents who had eaten
Great Lakes sport fish were aware of the
health advisory for fish; awareness differed
significantly by race, sex, educational level,
fish consumption, and state of residence
(Tildenetal., 1997).
$ 80% of minorities who had eaten Great Lakes
sport fish were unaware of the fish advisory,
and awareness was particularly low among
women (Tilden et al., 1997).
VK 97% of Native American men were aware of
local advisories against consuming Great
Lakes sport fish. However, 80% of the men
ate those fish (Fitzgerald et al., 1999).
-$• Fish is an essential component in the diets of
many minority populations and Native Ameri-
cans. These populations consume fish that
4-70
-------
POPs in the Great Lakes: Human Health Considerations
tend to have higher levels of contaminants
(Fitzgerald et al., 1996; Waller et al., 1996).
In response to these sociobehavioral and health
effects findings, advisories now target their mes-
sage and actions to vulnerable subpopulations, such
as pregnant women, nursing mothers, and chil-
dren. There are now 5 categories of consumption
advisory: (1) no consumption for the general popu-
lation, (2) no consumption for sensitive subpopula-
tions, (3) restricted consumption advisory for the
general population, (4) restricted consumption
advisory for sensitive subpopulations, and (5) a
commercial fishing ban. The value of strategically
targeted fish advisories has been demonstrated
through health education outreach efforts in two
populations of Native Americans. In these vulner-
able communities, body burden levels had been
elevated two- to eightfold for some POPs. These
levels were reduced through working with commu-
nity "gatekeepers" and organizing health fairs and
public meetings to provide information on cooking
practices to reduce exposures. The targeted inter-
vention strategies helped to reduce body burden
levels to U.S. population averages within a 6-year
period, without sacrificing fish as a nutritionally
important dietary component (Hicks et al., 2000).
The continuing need for fish advisories over the
entire Great Lakes region emphasizes that POPs
remain a major concern. However, the reductions
seen for POPs in many places are encouraging. In
particular, PCB concentrations in fish from the
Great Lakes region have declined over the years
(ATSDR, 2000). In 1985, coho salmon from Lake
Michigan contained 0.99 ± 0.6 ppm of PCBs,
whereas by 1992 the level was 0.78 ± 0.29 jug/9
(Eggold et al., 1996). Between 1976 and 1994,
mean levels of PCBs declined in Lake Ontario
rainbow trout from 3.9 to 0.97 ppm wet weight
(Scheider et al., 1998). Similar trends in PCB
levels were found for other fish species (ATSDR,
2000). These initial reductions in POPs levels
following pollution control by industry and through
government regulation have now, in a number of
instances, slowed or plateaued, unmasking the
importance of long-range atmospheric transport as
a continuing source to the Great Lakes (Figure
4-4; see Chapter 7, Appendix A). As stated by the
IJC (1996):
A
Tfe^
Apnl
October
Figure 4-4. 10-day back trajectories from Rochester, NY, for the year 1999. Color shading refers to the likelihood that
trajectories passed over a given area before arriving at the receptor site.
Source: Husar and Schichtel (2001).
4-77
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POPs in the Great Lakes: Human Health Considerations
A successful day's fishing.
Photo: ATSDR
We are increasingly recognizing that a variety
of pollutants emitted to and transported by the
air have become the major pathway of pollu-
tion to the Great Lakes. These pollutants may
come from direct sources, ... distant sources
in North America and beyond...
Additional detail on the deposition and contribution
of atmospheric transport loadings to the Great
Lakes can be found in Deposition of Air Pollutants
to the Great Waters, Third Report to Congress
(U.S. EPA, 2000).
Adverse effects from POPs have been demon-
strated on Great Lakes wildlife and in laboratory
studies at environmentally relevant levels. Similar
effects are reported in epidemiological studies of
human populations with high consumption of
Great Lakes fish. Many of these vulnerable popula-
tions are still being exposed to higher levels of
POPs than the general U.S. population. These
findings have national as well as international pub-
lic health implications because of the known toxic-
ity of these chemicals and their persistence and
ubiquity in the environment (Hicks et al., 2000).
The good news is that levels of POPs pollutants in
the Great Lakes environment have declined dra-
matically, particularly in the 1970s and 1980s.
This is a success story of primary prevention, in
this case pollution prevention through a partner-
ship among federal, state, and local regulatory and
health agencies, with industry and communities to
reduce emissions to the environment. More recent
trends in environmental levels are less clear, indicat-
ing a possible plateau and unmasking the impor-
tance of inputs from outside the Great Lakes basin
via atmospheric transport. Further progress in
reducing exposure levels will require increased
attention to pollution prevention, particularly to-
ward addressing long-range atmospheric sources.
Great Lakes sport fish still contain POPs levels that
are potentially harmful to human health, even
though two decades of environmental regulation
have significantly reduced chemical residues in
waters, sediments, fish, and shellfish (U.S. EPA,
2001). Considering the societal, cultural, and
health benefits (Albert et al., 1998) from fishing
and fish consumption, pollution prevention efforts
must be maintained consistent with the goal of
virtual elimination of POPs from the Great Lakes.
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To find a diet free from DDT and related chemi-
cals, it seems one must go to a remote and
primitive land, still lacking in the amenities of
civilization. Such a land appears to exist, at least
marginally, on the far Arctic shores of Alaska—
although even there one may see the approach-
ing shadow. (Rachel Carson, 1962)
llisks posed by persistent organic pollutants
(POPs) to Arctic ecosystems and human popula-
tions were central to the genesis of the Stockholm
Convention, and remain a primary concern when
evaluating potential POPs impacts. For the United
States, "Arctic ecosystems" means Alaska. Once,
not too long ago and within the living memory of
Native Alaskans, the Arctic was a pristine wilder-
ness where POPs were never used and could not
be detected in wildlife or humans. But the face of
Alaska is changing, with increasing urbanization,
industrialization, extractive resource activity, and
commercial and social contacts with the global
community. Accompanying these changes are
concerns that the physical, climatic, and social
aspects that make Alaska unique—particularly for
the indigenous population—also make this region
peculiarly prone to risks from global pollutants.
Although exposures to
POPs are being noted at
this time, their impact will
be more evident in the
future unless pollution
issues are addressed now.
As the data to follow
demonstrate, Alaska's
wildlife and human resi-
dents are experiencing
POPs contamination
from local, regional, and
international sources.
The levels in most envi-
Figure 5-1. Map of Alaska. Major roads in red.
With permission of the National Geographic Society
ronmental media typically remain substantially
below those found in highly polluted areas of the
lower 48 United States, but in high-trophic-level
feeding species—including killer whales and hu-
mans—some POPs levels have been recorded that
are comparable to those found in the general
United States population and similar marine mam-
mal species. POPs contamination of the Great
Lakes started as a predominantly regional and local
phenomenon, and the initial management suc-
cesses from domestic and binational strategies with
Canada reflected this scale. For Alaska, however,
the intervention options mandate a much more
global approach. From a polar perspective, "close"
to Alaska and its surrounding waters means the
huge and growing industrial and population centers
in Asia, less regulated neighbors just a few miles
distant in Russia, and sources across the Arctic
Ocean in Europe that are all closer than Washing-
ton, DC (Figure 5-1; polar projections in
Figures 5-2 and 5-4).
This review of POPs in Alaska links assessment of
human health with the state of the environment
and ecosystems. For Alaska Natives, there is a
deep connection among the air, the water, the
animals, and humans.
When people perceive
that they are one with
the environment, and
the environment is con-
taminated, then they
also are contaminated.
This integrated world
view differs from tradi-
tional "Western" prac-
tice, which has, in the
past, tended to separate
humanity from its sup-
porting ecosystems.
The many similarities in
5-7
-------
Alaska—At Risk
POPs toxicities between humans and other mam-
malian species suggest that it would be unwise to
hold to the belief that humanity is somehow imper-
vious to and distinct from impacts on the support-
ing ecosystems.
Why Is Alaska at Special Risk?
For a variety of reasons, the Arctic ends up as an
ultimate receptor and "sink" for POPs. The persis-
tence and potential effects of these deposited POPs
may also be more pronounced in polar climates.
Factors in evaluating POPs risks to Alaska include:
-& Location: The large expanse of the State of
Alaska, accentuated by its island chains (Aleu-
tians, Pribilofs), means that its neighbors are not
limited to the great ocean expanses or to
Canada and Mexico/Caribbean, as is the situa-
tion for the other United States. In addition to
Canada, Alaska's neighbors are Russia, Japan,
China, Korea, and other upwind Asian coun-
tries. Russia is the nearest trans-Pacific neigh-
bor, only a short kayak excursion away, and
human and wildlife populations regularly traverse
these artificial national boundaries.
-& Physical climate: Needless to say, winter is cold
in Alaska, but spring and summer are times of
relative warmth (Figure 5-2) and rapid biological
activity. The cycle of prolonged winter darkness
and cold, followed by warmth and 24-hour light,
places peculiar stresses on ecosystems. Through
the winter, mammals rely on fat stores, thereby
releasing lipid-soluble POPs within their bodies
as the fat is metabolized. In the spring melt,
POPs that have accumulated in the ice are re-
leased to the food chain during the limited time
of peak productive and reproductive activity.
And, throughout all of this, the predominantly
cold temperatures and permafrost reduce or
eliminate the microbial activity necessary to
degrade POPs.
% Ecological sensitivity: Cold temperatures and
long periods of darkness are associated in the
Arctic with slow growth, low productivity, and
low diversity in terrestrial ecosystems. Anthro-
pogenic damage to such ecosystems can require
a long period for recovery.
Arctic Monitoring and Assessment Programme
AMAP Assessment Report: Arctic Pollution Issues
January
180
90°E
90 "W
-48 -43 -38 -33 -28 -23 -II -13 -8-327 9-5 °C
July
180
90°W
7 9.5 =C
Figure 5-2. Arctic temperature profiles: January and
July. AMAP.
-$• Fat as the currency of life: Survival for all
species in polar climates rests on securing and
maintaining energy levels. Some animals have a
5-2
-------
Alaska—At Risk
round body design with thick layers of insulating
fat (e.g., fish, seals, walrus, and whales). An-
other strategy is to secure a regular supply of
high-energy food, as used by sea otters and
weasels. Fat is high-energy food. Polar bears
eat seals by killing them and then stripping off
and consuming the skin and fat. Likewise,
brown and black bears catch salmon and strip off
the skin and fat, which are consumed. Fat be-
comes the currency for survival in the Arctic.
Each predator targets the consumption of fat to
maximize energy transfer. In this process, lipo-
philic contaminants are passed efficiently up the
food chain and, at each trophic level, are
biomagnified, accentuated by both their persis-
tence and volume of consumption. This
economy includes humans near the top of the
web, as is evident in the fat rich diet of Alaska
Natives.
Human populations: A large proportion of
Alaskans are indigenous peoples—16% by the
2000 Census. In the more isolated regions of
the state, Alaska Natives make up a majority of
many community populations (Figure 5-3). The
indigenous population has a greater proportion
of children than the overall Alaskan population.
Obtaining wild food is central to the cultural,
religious, and economic identity and survival of
these peoples. Through traditional fishing,
hunting, gathering, and food processing, known
as subsistence, the culture and society of native
indigenous populations are maintained. Because
of concerns about contamination in subsistence
foods, people turn to the purchase of imported
foods. This is an economically untenable posi-
tion in remote Alaskan villages, as well as unfor-
tunate because foods purchased at stores also
contain POPs (Schecter et al., 1997; Schecter
and Li, 1997). Subsistence hunting and fishing
by humans at the top of the food chain also
relies on high fat intake, including the consump-
tion of other predators, which can compound
the biomagnification of POPs. Thus, the reli-
ance of Alaska's people on wild and traditionally
obtained local foods contributes to Alaskans'
concerns regarding international sources of
pollution (Hild, 1995).
Arctic Monitoring and Assessment Programme
AM1AP Assessment Report: Arctic Pollution Issues
—V 100 ODD
_. 50000
20000
— 10000
population
Figure 5-3. Total and indigenous populations of Alaska.
AMAP.
-& Previous absence of contamination: Com-
pounding Alaska's susceptibility is the recogni-
tion that its remote areas were previously uncon-
taminated, with little to no local use of POPs
pesticides and industrial pollutants except around
urban settlements and military bases (Durham et
al., 1961; Hayes et al., 1958). Any contamina-
tion comes in stark contrast to the expected
purity, even if Alaskan levels remain below those
in the lower 48 States. There is significant
economic value in safeguarding this food supply,
and likely more so in the future. This is particu-
larly significant for a region such as Alaska
where primary production (e.g., seafood) exports
to the rest of the United States and the world are
central to economic prosperity. Approximately
2 million tonnes of seafood are harvested annu-
ally from the Bering Sea alone, and over 80% of
the world's wild salmon are supplied by Alaskan
fishermen.
5-3
-------
Alaska—At Risk
POPs Transport to Alaska
POPs are transported through the environment to
Alaska through the movement of air, water, and
migratory species (e.g., fish, birds). These pro-
cesses are anticipated under the Stockholm Con-
vention and elaborated upon in Chapter 7 of this
report. Many physical aspects of the circumpolar
region now appear to contribute to a natural
transboundary movement of POPs to Alaska. Re-
view of these pathways in the context of a global
treaty must not, however, be interpreted as over-
looking the contribution of other regional or local
sources. Although Alaska has not had industrial
POPs manufacturers, there are incidents of past
usage that include military sites (e.g., PCBs) and
mosquito control efforts (e.g., DDT). Some local
waste burning may contribute byproducts (e.g.,
polychlorinated dioxins and furans). These are
under further domestic and local investigation, and
source reduction strategies are taking place.
Atmospheric Transport
Atmospheric air patterns move pollution from
around the Northern Hemisphere into the Arctic
(Figure 5-4; see also AMAP Arctic atmospheric
circulation maps with additional detail and seasonal
effects at www.amap.no). Winds blow in the
midlatitudes from west to east, bringing Asian air
into southern and central Alaska. During Russian
and Chinese nuclear testing in the 1960s and 70s,
Alaskans were concerned because they were a
short distance downwind. At the same time, in the
high latitudes of northern
Alaska, winds blow from
the east to the west,
bringing pollution from
northern and western
Europe.
As detailed in Chapter 7,
air movement can lead to
POPs transport and
deposition in two basic
ways: global distillation
of semivolatile chemicals,
and mass transport and
deposition of POPs at-
tached to dust and soot.
Figure 5-4. Atmospheric transport pathways to the Arctic
(Crane and Galasso, 1999, map 3).
For global distillation, a number of the POPs are
considered "semivolatile," evaporating in warmer
climates, moving north (or south) and then precipi-
tating out in colder climates. This cycle can repeat
itself, moving materials poleward in a process
known as the "grasshopper" effect (or global frac-
tionation and cold condensation) (AMAP, 1998;
Mackay and Wania, 1995; Wania and Mackay,
1993). In addition, all POPs can move to the
Arctic through episodic events that move dust
particles long distances. As demonstrated through
back-trajectory mapping and satellite imagery
(Chapter 7), Alaska is downwind of many Asian
and European sources.
The atmospheric peculiarities of the Arctic, and the
impact of global pollution, are most evident
through the phenomenon of Arctic haze. Arctic
haze is predominantly attributed to the movement
of sulfur oxides, hydrocarbon gases, and particles
north from their industrial sources. In the 1970s,
Matthew Bean, an Alaska Native Yupik elder from
Bethel, recognized that the plants were not as
green, the sky not as blue, and the horizon not as
clear as when he was a boy. He soon found him-
self talking with academic researchers who cor-
roborated his observations with their air quality
measurements. Arctic haze did exist (Rahn and
Lowenthal, 1984; Shaw et al., 1993). Further
research determined that this haze not only con-
tained pollution from the far north, but contami-
nants from all over the northern half of the globe.
The haze from these
materials becomes
increasingly dense dur-
ing the cold, dark win-
ter. In the spring, the
higher angle of the sun
warms the air, deepen-
ing the mixing layer and
depositing pollutants on
the earth's surface. The
return of the sun also
initiates a number of
biological activities and
unique photochemical
phenomena (Lindberg
et al., in press) leading
5-4
-------
Alaska—At Risk
to the "Arctic sunrise" effect. The deposition,
availability, and metabolic uptake of global con-
taminants into Alaska's plants, animals, and people
generally coincides with the commencement of
spring biological activity.
The very low water solubility of most POPs—
counterbalancing their high lipid solubility—leads
to water transport predominantly attached to fine
particles. However, some organic pollutants, such
as the hexachlorocyclohexanes (e.g., lindane) are
more soluble in water and can be transported
through a combination of prolonged persistence
in cold waters and large volumes of oceanic water
movement. Hydrologic pathways are also inter-
connected with atmospheric transport through the
semivolatile nature of POPs, where contaminants
can exchange between environmental media.
For Alaska, a combination of riverine and oceanic
transport can bring POPs from long distances.
The major rivers draining the agricultural and
industrial areas of Russia flow into the Arctic
Ocean. A number of Russian rivers are known to
have readily detectable levels of various pesticides,
including DDT, that do not appear to be decreas-
ing over time (Zhulidov et al., 1998). These rivers
release POPs to the Arctic Ocean, after which
contaminants can be transported by the prevailing
currents generally westward from the contaminated
Ob and Yenisey Rivers, and eastward from the less
contaminated Lena River.
Oceanic currents in the Pacific also provide a
transport pathway for contaminants (Figure 5-5).
After contaminants have traveled down rivers and
into the ocean from agricultural fields and indus-
trial areas of Southeast and Central Asia, the
western Pacific currents can carry these contami-
nants to other parts of the world. The currents
move along Japan, Korea, and Russia, and finally
flow through the Bering Sea and into the Arctic
Ocean (AMAP, 1998). Surface water studies of
PCBs have identified this movement and the
accumulation of materials within the Bering Sea
(Yao et al., 2001). Work from Japan on the
"Squid Watch Program" is tracking the move-
135-F
180"
>*--.
--_____ North Equatorial ^--••"'
3 ™~
--» —*• —•*- Equatorial C'ountercurrent—
Figure 5-5. Ocean currents impacting Alaska.
Source: Adapted with permission from Apel, 1987; NOAA.
ments of POPs in the North Pacific driven by the
prevailing west wind and the Kuroshio warm
current (Hashimoto et al., 1998).
Transport of contaminants from other regions of
the globe to the food supply of Alaska Natives and
other Americans can also occur through the move-
ment and harvesting of migratory species. The
springtime return of waterfowl is the first fresh
meat many Alaska Natives have after a long winter
of eating dried meat and stored foods. In addition
to adult birds, eggs are also collected and con-
sumed. Some of these birds have wintered in Asia
and Central America. In those regions, feeding
areas (such as fallow fields) may have been sprayed
with organochlorine insecticides. The bodies of
birds can carry pollutants that may be banned in
the American communities that consume them
(Figure 5-6).
Migratory fish do not travel as far as migratory
birds, but the mechanism for accumulation of con-
taminants is similar. Recently, it was shown that
the very low concentrations of HCB, s-DDT, and a
number of PCB congeners detected in sockeye
(red) salmon returning to interior Alaskan lakes can
5-5
-------
Alaska—At Risk
PACIFIC OCEAN
ADA
ARCTIC
OCEAN
SEA
ICE
V
SSI A
ATLANTIC OCEAN
^XiJ 1
^ I.: 'RU'S
• i I
H ' * '
Birds ol Prey
f-alconifonr.&s
Ducks
Geese
Artxur
Grebes
Potficeps
King
Tyranntdac
Loons
Gavia
Martins
Rip&ria
, Ay&thyo
^^^—• Ovenbirds
•'" Redheads
Robins
ErUnfKUS, LilShtn
Tunjus
Swifts
AftQdidotj
Swans
Cygnus
Thrush
Musctcopidoe
• - Warblers
EmMwemB
Figure 5-6. Migration routes of land, lake, and wetland birds (Crane and Galasso, 1999, Map #9).
contribute more POPs to the lake ecosystem than
the amount contributed by atmospheric deposition
(Ewald et al., 1998). No studies to date have as-
sessed the sources of chemicals that might be
found in low levels in fish species such as salmon,
capelin, and pollock that range in the Bering Sea
between the United States and Russia. These
commercial fish species end up on tables through-
out the world, and all have come from an interna-
tional ocean that receives water from the Western
Pacific and Asia (Crane and Galasso, 1999)
(Figure 5-7).
Further up the food chain, migratory marine mam-
mals cover large areas, consuming a variety of food
sources. These sources in turn lead to different
levels of POPs biomagnification. Most seals, sea
lions, toothed whales, and polar bears are near the
top of the food chain and move among interna-
tional waters (Crane and Galasso, 1999). Animal
species feeding lower on the food chain generally
have corresponding lower levels of POPs overall, as
well as different specific chemicals. Walrus and
bearded seals feed on benthic populations and
therefore have a different POPs profile than preda-
tors that feed on fish or other marine mammals.
Ringed seals eat crustaceans and fish. Likewise,
filter-feeding whales, such as bowhead whales, feed
low on the food chain, eating krill, and have a very
different POPs profile and lower levels overall than
the upper trophic level feeders.
POPs Levels in Alaska
Insights into levels and potential risks from POPs in
Alaska are best gained through comparing expo-
sure data to either effect levels in species of con-
cern or to levels found in the lower 48 States.
••
PACIFIC OCEAN
USA
CHINA
CANADA
/t R C 7 11
OCEAN
SEA
ICE
RUSSIA
ATLANTIC OCEAN
J J
Figure 5-7. Migration routes of salmon (Crane and
Galasso, 1999, Map #13).
5-6
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Alaska—At Risk
Although zero levels would be the preferred value
for all of the POPs, it must be recognized that with
the global distribution of these pollutants, their
persistence, and modern laboratory equipment,
scientists will invariably be able to detect some level
of pollutant, especially in species higher on the
food chain. This complexity is compounded by the
multiple environmental media and species in which
measurements are taken, and the multiple POPs
and their metabolites under consideration. Care
must also be taken in comparisons between differ-
ent studies because units of measurement, analytic
protocols, and methods of reports may vary.
For this report, we compare levels found in Alaska
to those in the lower 48 States and, where pos-
sible, to the effect levels found in these or similar
species from other areas of the United States.
Reflecting the integrated nature of the Alaskan
situation, the species discussion commences with
wildlife, proceeds through wildlife that are used as
food, and concludes with human consumers. For
those seeking additional details on species levels
across the Arctic, excellent references are available
in AMAP (1998), Canadian Northern Contami-
nants Program (Jensen et al., 1997), Landers and
Cristie (1995), and Ritter et al. (1995).
Bald eagle.
Photo: U.S. Fish and Wildlife Sen/ice
The decline of bald eagle populations to the verge
of extinction in the lower 48 States is emblematic
of the effect of POPs, DDT/DDE in particular.
Although residual DDE contamination continues to
affect reproductive rates in some areas, the recov-
ery of bald eagle populations in the lower 48 States
following the cessation of DDT use and protection
as an endangered species has been a remarkable
4
3.5"
2.5
1.5
p.p' - DDE in Aleutian Bald Eagle Eggs
Estimated DDE effect level
Kiska Amchitka Tanaga Adak
i'CU Aroclor 1260 in Aleutian Bald Eagle Eggs
1.5
0.5
Kiska
Amchitka
Tanaga
Adak
Figure 5-8a,b. Bald eagle levels of DDT and PCBs in the Aleutians (Anthony et al., 1999), geometric mean
values.
5-7
-------
Alaska—At Risk
success. In Alaska, bald eagle populations have
remained robust, with DDT/DDE levels generally
well below the potential effect level of —3.6 ug/g
DDE (Anthony et al., 1999; Wiemeyer et al.,
1993). Eagles nesting along the Tanana River in
the interior of Alaska in 1990-91 had DDE levels
below concentrations known to result in sublethal
or lethal effects, and most organochlorine concen-
trations were an order of magnitude lower than
concentrations in bald eagle eggs from elsewhere in
the United States (Richie and Ambrose, 1996).
However, even in the presence of this apparent
success there are warning signs. Eagles in the
western Aleutian Islands have been found to have
ratios of DDT/DDE that indicate new DDT
sources, and DDE levels in some eggs on one
island (Kiska) may be depressing reproductive suc-
cess (Anthony et al., 1999; Estes et al., 1997)
(Figure 5-8). Although the sources are not yet
known, the prey species, especially migratory birds
from Asia where DDT is still used, need to be
assessed further. It also should be noted that al-
though DDE is suspected as the causative agent in
the above-mentioned studies, DDE concentrations
in eagle eggs were positively correlated with other
organochlorines, including oxychlordane, beta-
HCH, dieldrin, and hexachlorobenzene.
Peregrine falcon.
Photo: U.S. Fish and Wildlife Service
Historic declines in peregrine falcon populations at
several locations, including Alaska, have been
correlated with DDE concentrations in their eggs
causing eggshell thinning and hatching failure
(Ambrose et al., 1988a,b; 2000). Threshold con-
centrations of —15-20 ppm p,p'-DDE have been
associated with a 20% eggshell thinning in per-
egrine falcons (Peakall et al., 1990). Populations
are expected to decrease if eggshells are at least
17% thinner than pre-DDT measurements (Kiff,
1988). Peregrine falcons in interior and northern
Alaska declined during the 1960s, stabilized in the
mid-1970s, began to increase in the late 1970s,
and have since stabilized or continued to increase.
Eggs from two subspecies of peregrine falcons
were collected from interior and northern Alaska
between 1979 and 1995 and analyzed for orga-
|p,p'-DDE in Peregrine Falcon Eggs from Alaska
I Time Series
50
1979-84 1988-90 1991-95 1979-84 1988-90 1991-95
American peregrine Arctic peregrine
Sum-PCB in Peregrine Falcon Eggs from Alaska
Time Series
30
25
20
I
c.
10
1
I
I
( 1979-84 1988-90 1991-95 1979-84 1988-90 1991-95
( American peregrine Arctic peregrine
Figure 5-9a,b. Time trends for DDE and PCBs in Alaskan
peregrine falcon eggs (Ambrose et al., 2000). Geometric
mean and range, (n = 19—32)
5-1
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Alaska—At Risk
nochlorine compounds and metals (Ambrose et al.,
2000) (Figure 5-9). This study represents one of
the few relatively long-term data sets from Alaskan
biota and can offer some insight into POPs residue
trends with time. In general, organochlorines
declined over time, although the trend was not as
strong for PCBs, which declined more slowly.
These results agree with trends observed in other
peregrine falcon populations, which show that
PCB concentrations have not decreased as clearly
as other organochlorine compounds (Peakall et al.,
1990; Newton et al., 1989; Johnstone et al.,
1996). Although organochlorine levels have de-
creased over time, evidence for cumulative and
single-contaminant reproductive effects was found
in remote locations (Ambrose et al., 2000). Con-
taminant monitoring remains a necessary manage-
ment tool for this species, which is recovering from
near extinction caused largely by environmental
contaminants, and continues to remain vulnerable
to persistent and bioaccumulative compounds.
Killer whales spy-hopping.
Photo: Craig Matkin
Certain populations of killer whales (Orcinus orca)
have been extensively studied over the past 30
years, including populations in Puget Sound, Wash-
ington, the inside waters of British Columbia,
Southeastern Alaska, and Kenai Fjords/Prince
William Sound, Alaska. The POPs concentrations
found in some populations of Alaskan killer whales
are similar to those recently reported in pinnipeds
and cetaceans that occur in more contaminated
waters (Ylitalo et al., 2001). Levels of total PCBs
in blubber ranged up to 500 ppm, and total DDTs
ranged up to 860 ppm, while median levels and
some group levels were significantly lower (Figure
5-10). Concentrations of POPs in transient killer
whale populations (marine mammal-eating) were
much higher than those found in resident animals
(fish-eating), apparently because of differences in
diets (amounts and types of fat consumed) and
feeding locations (localized or broad-ranging)
(Ylitalo et al., 2001). Both resident and transient
whale groups described in the report reside in
Alaskan waters, although the transient pods may
move hundreds of miles up and down the coast
beyond Alaska and through international waters.
2500
Resident
Transient
t/5
Resident
Transient
Figure 5-10. Dioxin TEQ and sum-DDT in Alaskan
resident v. transient killer whales (Ylitalo et al., 2001).
Mean denoted by horizontal line, range as vertical bar.
5-9
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Alaska—At Risk
Life-history parameters such as sex, age, and re-
productive status also influence the concentrations
of POPs in Alaskan killer whales. Reproductive
female whales contain much lower levels of POPs
than sexually immature whales or mature male
animals in the same age class. This is likely due to
transfer of POPs from the female to her offspring
during gestation and lactation. Birth order also
influences the concentrations of POPs. Adult
male, resident, first-born whales contain much
higher POPs concentrations than are measured in
subsequent offspring to resident animals in the
same age group (Ylitalo et al., 2001). There is also
some evidence of decreased survival of the firstborn
transients that have the highest POPs levels
(Matkinetal., 1998, 1999).
Reports of POPs levels in killer whales have been
associated with decreases in reproductive success
(Matkin et al., 1998, 1999). The causal factors for
low reproduction and population decline of certain
transient groups of killer whales from Prince Will-
iam Sound/Kenai Fjords are not known. The low
reproduction and population decline may be a
natural cycle, related to human factors (e.g., oil
spill), exposure to natural toxins (e.g., biotoxins),
decline in the primary prey species (harbor seal), or
a combination of environmental and anthropogenic
factors. Exposure to toxic POPs may also be a
contributing factor (Ylitalo et al., 2001).
Sea otters.
Photo: Craig Matkin
Sea otters have declined precipitously throughout
the Aleutian Islands over the past decade (Estes et
al., 1998). Although investigations to date suggest
predation may be the primary cause of the decline,
contributing factors such as contaminants have not
been completely ruled out. Sea otters at several
Sum-DDT Levels in Sea Otters
0.9
0.8
0.7
I °-6
5 0.5
I 0.4-
a 0.3
^ 0.2
0.1
0
Aleutian
SE Alaska
= 0.001
California
PCB and Chlordane Levels in Sea Otters
0.35
Aleutian SE Alaska California
D Sum-PCB • Sum-chlordane
Figure 5-lla,b. Comparison of POPs levels in Aleutian
(n=7), Southeastern Alaskan (n=7), and California (n=9)
sea otters (Bacon et al., 1999). Mean values.
5-10
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Alaska—At Risk
isolated sites in the Aleutians (Adak, Shemya) have
been recorded with elevated levels of certain POPs,
particularly PCBs (Giger and Trust, 1997). PCB
levels in sea otters from the Western Aleutian Is-
lands (Adak and Amchitka Islands) were somewhat
higher than levels found in California sea otters,
and were significantly elevated relative to PCB
concentrations in sea otters from southeast Alaska
(Bacon et al., 1999) (Figure 5-11). The relative
contribution to PCB levels in Aleutian sea otters
from long-range sources compared to local con-
tamination from old defense sites cannot be ascer-
tained using currently available data (Bacon et al.,
1999; Estes et al., 1997). Sum-DDT levels in
Aleutian otters, although much higher than the
very low values found in Southeast Alaska, remain
substantially lower than in California otters. These
sum-DDT concentrations were not in the range
that causes reproductive impairment in captive
mink, a commonly used comparison and related
species. However, there is little information that
can help evaluate whether there may be interactive
effects among POPs and other stressors affecting
Aleutian sea otters.
Species Consumed by Humans
Beluga
Beluga whales (Delphinapterus lucas) are a pre-
ferred food for many Alaska Natives. The muktuk
(the skin and outer layer of fat) is considered a
choice item for consumption. This outer layer of
fat contains the highest levels of POPs in the ani-
mal (Wade et al., 1997). The blubber of beluga
whales from Alaska contains POPs in concentra-
tion ranges similar to those found in beluga whales
from the Canadian Arctic (Muir and Norstrom,
2000) but much lower than levels in whales from
the highly contaminated St. Lawrence River in
eastern Canada (Krahn et al., 1999) (Figure 5-12).
Within Alaska, the low levels in the Cook Inlet
stock are noteworthy, as these animals reside in
150
130
110
so
70
50
30
10
01
'
r
£a
c
sum-DDT
Hr^
t
i
i 1?
I
CO
£
p.
£ in
CO
i
*-f
1
I 1
a
in
|
§
s
CO
I
o
lU
a a,
TO o
S 7i
i
5*
Figure 5-12. Sum-DDT levels in beluga blubber. Mean (») +/— one standard deviation (vertical bar) (Becker
et al., 2001).
5-77
-------
Alaska—At Risk
Beluga whales.
Photo: NOAA
one of the most "urban" areas of Alaska, where
anthropogenic contamination could be expected to
result from the relatively higher density of human
residents and commercial activities (Krahn et al.,
1999).
Gender is an important factor to consider when
interpreting differences in POPs concentrations
among beluga whale stocks (Krahn et al., 1999).
For example, the adult males of each stock had
higher mean concentrations of all contaminant
groups than did the adult females of the same
stock. This is considered to be an effect of POPs
transfer from the mother to the calf during gesta-
tion and lactation. This theory is supported by the
finding that upon reaching sexual maturity, the
levels of toxaphene, PCBs, DDTs, and chlordane
steadily go down in females as they produce calves
and lactate (Wade et al., 1997).
The bowhead whale stock (Balaena mysticetus)
migrates through the Bering, Beaufort, and
Chukchi Seas and is listed as an endangered spe-
cies. Alaska Natives are the only U.S. citizens
permitted to harvest the bowhead whale for food.
Studies have shown relatively low levels of PCBs in
bowhead whale (Figure 5-13) blubber, but these
levels tend to increase with age (McFall et al.,
1986; O'Hara et al., 1999). Previous reports
support the view that these large filter-feeding
whales, consuming at a lower level on the food
chain, have lower concentrations of POPs in their
Bowhead whales.
Photo: NOAA
blubber. Toothed whales, eating higher on the
food chain, may have one or two orders of magni-
tude more POPs than the filter-feeding whales
(O'Hara and Rice, 1996; O'Shea and Brownell,
1994; Borell, 1993).
0.5
0.45
0.4
3 °-3
f* °'25
S 0.2
83
£ 0.15
3 o.i
0.05
0
I.-.I-.-I
^ ^
Figure 5-13. POPs levels in bowhead whale blubber
(O'Hara et al., 1999). Mean values. n=26.
The various seal species in Alaska constitute a
substantial portion of the marine mammal diet of
numerous predator species, including humans.
Blubber samples from four Alaskan seal species
(bearded seal, Erignathus barbatus; harbor seal,
Phoca vitulina; northern fur seal, Callorhinus
ursinus; ringed seal, P. hispida) have been col-
5-12
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Alaska—At Risk
Northern fur seals.
Photos: Suzanne Marcy
lected and analyzed for POPs contaminants (i.e.,
total PCBs, total DDTs, total chlordanes, HCB, and
dieldrin) (Krahn et al., 1997). Harbor seals, fre-
quently consumed by Alaska Natives, were found to
have low but measurable levels of several of these
POPs (Figure 5-14). The concentrations of POPs
in harbor seals from Prince William Sound were
generally much lower (e.g., total PCBs up to 100-
fold and total DDTs up to 30-fold lower) than those
recently reported for harbor seals from the north-
western U.S. mainland, including animals involved
in mass mortality events (Krahn et al., 1997) (see
Chapter 6, Marine Ecosystems). For Alaska, how-
ever, in contrast to other parts of the United
States, the potential for POPs biomagnification
continues through the consumption of harbor seals
by humans, an additional one or more trophic
levels higher.
Notable among the multiple studies of seal species
is the finding that POPs concentrations in male
subadult northern fur seals sampled in 1990 at St.
Paul Island in the Bering Sea were higher than
1
1
h 5
1
•§ 9 -
w 1
1 1
]
! 1
j I
1 1
B 1=1
1 1
B H
s-PCB Prince s-PCB s-DDT Prince s-DDT s-Chlordane s-Chlordane
William S. WA/OR coast William S. WA/OR coast Prince WA/OR coast
WilliamS.
concentrations in the ringed and bearded seals
from the Bering Sea or in the harbor seals from
Prince William Sound. Fur seals feed mainly on
oceanic species such as squid and pollock. Female
and juvenile fur seals migrate long distances into
the open ocean of the northern Pacific far south of
Alaska and even to the shores of Japan, as well as
California. The higher POPs concentrations in fur
seals are consistent with exposures occurring dur-
ing these long oceanic migrations. Harbor seals
feed on different species of fish that tend to be very
coastal, like perch. Harbor seals do not migrate,
but stay close to their coastal feeding and haul-out
areas.
Steller Sea Lion
Figure 5-14. POPs levels in Alaskan v. West Coast U.S.
harbor seals (Papa and Becker, 1998). The "s" prefix
indicates summation of related chemical substances.
Steller sea lions.
Photo: NOAA
Studies show that PCBs are the predominant POPs
in sea lion blubber, followed by levels of DDT/
DDE. Levels of chlordane compounds were an
order of magnitude lower. Higher concentrations
of PCBs and DDTs were found in Steller sea lions
from Alaska compared to those from the Bering
Sea, indicating that the populations have different
sources of exposure (Lee et al., 1996). Like beluga
whales, as Steller sea lion females become sexually
mature they show a dramatic decline in POPs
levels. It has been calculated that they may lose
80% of their PCBs and 79% of DDT/DDE through
lactation while nursing the first pup (Lee et al.,
1996). Two studies of PCBs in Steller sea lion
blubber found an average of 23 ppm (Varanasi et
al., 1993) and 12 ppm in males (Lee et al., 1996).
5-13
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Alaska—At Risk
These PCB levels in Steller sea lions generated
concern among local subsistence populations, who
requested an evaluation of potential human health
impacts (Middaugh et al., 2000a,b; see following).
Salmon
Alaskan fisher and sockeye salmon.
Source: NOAA
Salmon species are key to Alaska's commercial
fisheries and to the well-being of many subsistence
communities. For the Alaskan fishing industry,
salmon is a billion-dollar business. For subsistence
communities who catch and consume their own,
fish by weight make up about 59% of the total
subsistence harvest for Alaska Natives, with salmon
being the most important species (AMAP, 1998).
In western Alaska, the fish harvest can approach
220 kg (485 Ib) per person per year and make up
more than 73% of all locally harvested food (Wolfe,
1996). The U.S. Fish and Wildlife Service and
Alaska state government are currently assessing
contaminant levels and evaluating fish health in
salmon from selected Alaskan rivers.
The migratory and reproductive patterns of sock-
eye salmon (Oncorhynchus nerka) are known to
provide a means of transport for very low levels of
chemicals such as PCBs and DDT to waters used
by other species of Alaskan freshwater fish, such as
grayling (Thyma//us arcticus) (Ewald et al., 1998).
Migrating salmon carry these low but measurable
levels of POPs to spawning areas where, after
spawning, they die and decay. The POPs then
become bioavailable to other local species. The
levels of POPs delivered by salmon to Alaskan
interior lakes and rivers have been estimated to be
slightly above the levels deposited through atmo-
spheric means, although these levels are far below
those found in fish from the Great Lakes region
(Figure 5-15).
Arctic Monitoring and Assessment Programme
AMAP Assessment Report: Arctic Pollution Issues
•'<," *
-------
Alaska—At Risk
this area is dominated by eastward airflow from
Asia and the North Pacific Ocean. Sources of
POPs in the Bering, Chukchi, and western Beau-
fort Seas are, therefore, more likely to have origi-
nated in eastern Asia. PCBs were generally used
less often in Asia, except Japan, than in North
America and Europe (Norstrom et al., 1998). The
U.S. Fish and Wildlife Service, Office of Marine
Mammal Management, continues to work with
Alaska Native hunters to collect samples for analy-
sis of environmental contaminants.
Polar bear.
Photo: U.S. Fish and Wildlife Service
Polar bears are at the top of the Arctic marine food
web. Norstrom et al. (1998) investigated chlori-
nated hydrocarbon compounds in polar bears from
much of the circumpolar Arctic. They found
strong relationships among contaminant concentra-
tions and sex. Individual dietary preferences, re-
gional differences in species availability, and food-
chain structure also contributed to variability within
the data. For example, baleen whale and walrus
carcasses may be seasonally important food
sources for polar bears in the Bering Sea and
Chukchi Sea region, supplementing their primary
diet of ringed and bearded seals. Walrus (except
when eating seals) and baleen whales feed at lower
trophic levels than other Arctic marine mammal
species. Conversely, polar bears feeding on beluga
carcasses in eastern Canada exhibit higher POPs
levels. Thus, prey selection can affect the pattern
of chlorinated hydrocarbon uptake in these differ-
ent polar bear populations. Total chlordanes (sum
of 11 chlordane-related compounds) were the most
uniformly distributed POPs in this study, reflecting
a similar pattern found in air and seawater sam-
pling (Norstrom et al., 1998).
Although sample sizes were small, concentrations
of total PCBs, total chlordanes, DDE, and dieldrin
in polar bears from the Bering, Chukchi, and west-
ern Beaufort Seas tended to be among the lowest
in the study area. The atmospheric circulation of
Alaska Native child with eggs—a subsistence food.
Family photo: Jesse Paul Nagaruk
Food is central to culture. Alaska Natives, although
sharing different cultural heritages, are linked to
their environment through the foods that they
gather locally and consume. The social structures
that define behavior in the sharing of subsistence
harvests and through feasts are the traditions of
Alaska Natives—the cultural values of the people.
Children and youth are taught about their environ-
ment and about their relationship to the commu-
nity through hunting, fishing, gathering, and shar-
ing. The survival knowledge of the group is passed
5-75
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Alaska—At Risk
down from generation to generation, ensuring the
transmission of language and values. The work of
obtaining one's own food is rigorous and promotes
self-reliance and self-esteem. For all of these fac-
tors, continued confidence in the quality of locally
obtained foods is essential (Egeland et al., 1998).
Alaska Natives eat 6.5 times more fish than other
Americans (Nobmann et al., 1992). Under the
Marine Mammal Protection Act, Alaska Natives are
the only people in the United States allowed to
hunt marine mammals, which they then eat. By
doing so, Alaska Natives consume predator species
(seals, sea lions, bears, and toothed whales) at the
very top of the food chain. Many Alaskans have
wide seasonal variation in their dependence on
locally available foods. Their diet shifts in response
to short intense summers and the migration of wild
birds, fish, and mammals. Alaska Natives eat more
fat, albeit different types, than most U.S. citizens.
Marine mammal fats and fish oils differ significantly
from pork and beef fats in their ability to provide
health benefits (Jensen and Nobmann, 1994;
Nobmann et al., 1992; Scott and Heller, 1968).
Estimates of the amount and type of subsistence
foods consumed by Alaska Natives are summarized
in Figure 5-16, documenting levels of dependence
and species preferences by area.
In regions where employment opportunities are
scarce or seasonal, locally obtained foods remain
an economic necessity. Shifting food consumption
in remote Alaskan communities is not beneficial for
several reasons. Food that is purchased is expen-
sive and rarely fresh owing to the long distances it
must be shipped and the number of times it must
be handled as it goes into smaller and smaller
stores. Many people in these remote communities
have very limited food budgets because of the
scarcity of jobs and high costs of heating and other
costs associated with life in a remote and challeng-
ing environment (Egeland et al., 1998).
Store-bought foods in remote Alaskan communities
need to have a long shelf life. Therefore, the foods
have been frozen, canned, or chemically preserved.
Many of these foods do not have the nutritional
value of fresh foods from the local area. Store-
Arctic Monitoring and Assessment Programme
AMAP Assessment Report: Arctic Pollution Issues
Southwest/ ,
Aleutians °/°
oO
60
40
20
0-
Kodiak Island
iV
I I fish
Kg/person/year | | Terrestrialmammals
-300
| | Marine mamma 1.5
I I Other (birds, shellfish, plants)
1511
50
Figure 5-16. Total and composition of subsistence
production in Alaska. AMAP.
bought foods are much higher in processed sugars,
saturated fats, sodium, and simple carbohydrates,
contributors to such conditions as obesity, diabetes,
heart disease, and dental caries. These conditions
are growing at alarming rates in Alaska (APHA,
1984; Ebbesson et al., 1996; Lanier et al., 2000;
Nobmann et al., 1992; Nobmann et al., 1998;
Nutting, 1993; Schraer et al., 1996). Health sur-
veys have also indicated that, in some communi-
ties, the individuals who are most concerned about
environmental pollution are the same people who
most frequently consume less traditional foods and
are shifting to buying food from the store (Dewailly
et al., 1996; Egeland et al., 1998; Hild, 1998).
Adding to concerns about contaminants in local
foods, Alaska Natives have reported changes in the
subsistence species they hunt. These changes
include seals with diseases they have not seen
before, no hair, yellow fat, fat and meat that does
not taste as it should, and seals with abnormal
5-76
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Alaska—At Risk
growths and abnormal sex organs. Similar con-
cerns have been raised about other subsistence
species. These observations, collected now by the
Alaska Native Science Commission, may contribute
to an understanding of what is occurring in the
changing Arctic (www.nativeknowledge.org). In
the absence of key information to answer specific
questions, and in response to media reports about
contamination of the Arctic, the conclusion being
reached by many Alaska Natives is that the animals
may not be healthy, and the health of their children
may be at risk.
POPs Levels in Alaska Natives
Most of the POPs under the Stockholm Conven-
tion were never used in or near Alaska. For the
other POPs (e.g., PCBs, DDT, polychlorinated
dioxins/furans), local use in Alaska and emissions
to the environment are much less than has oc-
curred in the lower 48 states. Yet there is consider-
able concern among residents—particularly Alaska
Natives—that they may have become contaminated
through consuming traditional foods. The most
expeditious way to assess the extent to which Alas-
kans have been exposed to these persistent toxic
substances is to measure levels in human tissue
(Hild, 1995). Unfortunately, there is no statistically
based survey of POPs levels in Alaskans. Indeed,
there is no national statistically based survey of
POPs levels in the U.S. population, although serum
has been collected under the NHANES IV study
and is being analyzed at the Centers for Disease
Control and Prevention (CDC).
POPs levels have been measured in small studies of
selected Alaska Natives, lower-48 background
comparison groups, and Great Lakes fishers, pro-
viding valuable indicative and comparative informa-
tion on POPs levels (Figures 5-17 and 5-18).
These data can help inform hypotheses and con-
clusions regarding sources of human exposure to
POPs and the resulting concentrations and trends.
For example, as with marine mammal exposures,
high trophic level feeding is generally more prob-
lematic than lower on the food chain. Thus, it can
be hypothesized that Alaska Native diets based on
plants and plant-eating animals are of less concern
Crt
1 60
3 «m
IT °°
3 40
I
"8. ^n
ft
2
w
1 m
a
H n
DCoplanarPCB"
• Furan Total TEI
DDioxin Total Tt
FEC
SC
Aleutian Comparison Great Lakes
volunteers population - fishers
Arkansas
Figure 5-1 7. Serum dioxin toxicity equivalence
concentrations (TEC) in Aleutian volunteers (n=48)
compared with Arkansas (n=70) and Great Lakes fisher
(n=31) comparison groups (Middaugh et al., 2000a).
than those relying on the consumption of marine
mammal predator species. The importance of
location and proximity to emission sources and
transport pathways can also be evaluated, as the
western Aleutians represent a quite different locale
from the Beaufort Sea off northeastern Alaska.
Likewise, the subject's age may be a major deter-
minant of many POPs levels. As has been evident
in lower-48 studies, POPs levels tend to increase
with age because of the fundamental persistent and
bioaccumulative nature of the contaminants, espe-
•7 _
t
3 c
8 4
§ 4
'•S i -
-------
Alaska—At Risk
daily in males where there is no excretion through
lactation. Age is also an important consideration
in evaluating Alaska Native levels, as dietary prac-
tices and the proportion of traditional foods in
many diets have changed over recent years.
In response to citizen concerns, the State of
Alaska, Department of Health and Social Services,
conducted a targeted study of POPs in five Aleutian
communities (Middaugh et al., 2000a,b, 2001).
These communities had become concerned be-
cause some Alaskan Steller sea lion blubber had
been reported to contain relatively high levels of
PCBs (23 ppm, Varanasi et al., 1993; 12 ppm in
males, Lee et al., 1996) potentially impacting their
use of sea lions as a source of meat and oil. As
graphed in Figure 5-17, total PCB, dioxin, and
furan toxicity equivalence concentrations (TEC)
levels in the Aleutian volunteers (Middaugh et al.,
2001) were similar to those in the background U.S.
population (Arkansas) and considerably below
fisher exposures on the Great Lakes (Anderson et
al., 1998). Middaugh et al. (2000a) also analyzed
the age relationship to concentration levels (Figure
5-19), demonstrating increased POPs levels with
age. Similar age-related findings are evident in
other studies from lower-48 populations and can-
not necessarily be ascribed to dietary pattern
changes. Because the Aleutian sample sizes were
very low and from volunteer populations in iso-
lated, select communities, few conclusions can be
drawn, and a broader surveillance is needed to
J.I
I
Figure 5-19. Distribution of serum PCB concentrations in
Aleutian volunteers as a function of participant's age
(Middaugh et al, 2000a).
answer key questions and address community
concerns.
A small group of Aleut women of childbearing
age—not pregnant at the time—was identified in
the Middaugh et al. (2001) study. If their levels
were to be compared with the maternal plasma
study data of the Arctic Monitoring and Assess-
ment Programme (AMAP, 1998), the Aleut women
would have the highest levels of p,p'-DDE (geo-
metric mean 0.503 ppm lipid) so far found in the
circumpolar region. They were second highest
among the other Arctic nations for trans-nonachlor
(g. mean 0.0498 ppm lipid) and oxychlordane (g.
mean 0.0285 ppm lipid) (Middaugh et al., 2001).
Note, again, that the Aleutian studies are only
preliminary and cannot be considered statistically
representative of this population. The relative
elevations of DDT and chlordane derivatives are,
however, consistent with the location of the Aleu-
tians near continuing use regions for these POPs in
Asia.
From the other side of Alaska, Arctic Slope moth-
ers have POPs levels (DDT, DDE, mirex, trans-
nonachlor, oxychlordane, and PCBs) that are lower
than those in the Aleutian/Pribilof Islands women
of childbearing age (Simonetti et al., 2001). These
levels are comparable with levels in the lower 48
states for background populations (Anderson et al.,
1998).
At this time, POPs movement and deposition
trends to the north are unknown. An ongoing
national surveillance program has not been in place
to clearly indicate whether the 12 POPs under the
Stockholm Convention are increasing, stable, or
decreasing. There is an indication that in other
Arctic nations some forms of PCBs are declining,
whereas no trends are apparent for the more chlo-
rinated forms (Hung et al., 2001).
Human health and ecological research on POPs
levels and effects in Alaska is increasing, linking the
domestic and transpolar efforts of the Arctic Moni-
toring and Assessment Program (AMAP), Arctic
Council, U.S. federal agencies, Alaska state gov-
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Alaska—At Risk
ernment, and tribal groups. These research efforts
cover a spectrum from expanding work on environ-
mental levels through measurements of body bur-
dens and effects along the food chain to wildlife
and humans. Emphasis is placed on community
involvement in the planning, decision making, and
communication of this work. Among these re-
search efforts, measurements are underway of
POPs levels transported in the air to Alaska and of
levels in water and sediments of the Yukon River.
Studies have been conducted on POPs levels in a
wide range of species including chinook and chum
salmon, Stellers eiders, black-capped chickadees,
red-throated loons, and wood frogs. This research
is accompanied by expansion of data collection on
marine mammals and other high-trophic predators,
notably bald eagles and polar bears. With Alaska
Natives, traditional food practices are being docu-
mented and analyzed to assess not only the con-
taminant loads but also the nutritional benefits of
the diet. POPs levels in mothers and the umbilical
cord blood of their offspring are being measured to
assess the body burden of contaminants. These
data serve as an essential link in studies of potential
effects (e.g., developmental, immunological) on the
children. Research data have also been published
as part of ongoing studies assessing the link be-
tween POPs levels and breast cancer (Rubin et al.,
1997) and on the effect of HCB and DDE in hu-
man cell cultures (Simonetti et al., 2001).
These research efforts in Alaska parallel the POPs
reduction and elimination activities under the
Stockholm Convention. While the current Alaskan
data outlined in this chapter serve to inform U.S.
consideration of the Stockholm Convention, the
ongoing work will further help to:
•ft! Monitor increases or declines in POPs levels in
Alaska
•ft! Detect any wildlife or human hotspots of POPs
contamination
•ft- Identify potential domestic and international
sources of ongoing POPs contamination
•ft' Guide communities on the risks and benefits of
traditional practices
Increase the general scientific knowledge of the
effects of these toxic substances and the levels at
which these effects occur.
POPs can now be measured in all environmental
media and species in Alaska. POPs levels in Alaska
are generally low, however, when compared to the
lower 48 United States. Accompanying these
comparatively low levels are isolated examples of
elevations that portend a cautionary warning in the
absence of international action. DDT/DDE and
PCB levels in transient Alaskan killer whales are as
high as those found in highly contaminated east
coast dolphins, reaching to the hundreds of parts
per million in lipid. On Kiska Island in the Aleu-
tians, DDE concentrations in bald eagle eggs ap-
proach effect levels seen in the Great Lakes. And
Aleuts have some of the highest average DDE and
chlordane levels measured in Arctic human popula-
tions, highlighting their proximity to continuing
emission sources in Asia. Indeed, Alaska's loca-
tion—geopolitically and climatically—suggests that
POPs pollution could be exacerbated in future
years in the absence of international controls.
The hunting and dietary practices essential to sur-
vival in the Arctic make indigenous humans and
wildlife especially vulnerable to POPs. Where
animal fat is the currency of life, this intensifies the
unique combination of POPs properties to migrate
north, associate with fat, persist, bioaccumulate,
and biomagnify. For Alaska Natives, current POPs
levels vary with location and diet. In the human
populations measured (Aleutian, Pribilof, North
Slope), POPs levels are similar to those experi-
enced by the background U.S. population, and
generally below those of fisher communities around
the Great Lakes. It is, therefore, important to
emphasize that there are no known POPs levels at
this time in Alaska that should cause anyone to
stop consuming locally obtained, traditional foods
or to stop breastfeeding their children. Current
information indicates that the risks associated with
a subsistence diet in Alaska are low, whereas in
contrast the benefits of this diet and breastfeeding
children are well documented (Ebbesson et al.,
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Alaska—At Risk
1996; Jensen and Nobmann, 1994; Nobmann et
al., 1992; Scott and Heller, 1968; Bulkow et al.,
2002). Further investigation and assessment are
needed for specific species and foods in traditional
diets, and to broaden the database across Alaskan
communities. The international AMAP (1998)
report came to the same conclusion for the entire
Arctic, and Alaskan levels of most of the POPs are
generally lower than for other polar nations. The
international community has also moved to further
reduce POPs contamination through negotiation of
the Stockholm Convention on POPs, implementa-
tion of which should help minimize future increases
in levels of the listed POPs.
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I he accumulation and effects of persistent organic
pollutants (POPs) in marine ecosystems testify to
the magnitude and global scale of these pollutants.
On the coasts of the continental United States,
POPs concentrations in some marine mammals
reach very high levels, such as in the bottlenose
dolphins familiar off the Atlantic coast. In remote
regions in the middle of the North Pacific Ocean,
thousands of miles from industrial centers, albatross
have been found to have high PCB and dioxin
levels that may be interfering with their reproduc-
tive success. And POPs are now measured, albeit
at much lower levels, in remote reaches of the
Southern Hemisphere and Antarctic. Although
these oceanic ecosystems often fall under no na-
tional jurisdiction, they are valuable economic and
esthetic resources for all. The species that inhabit
these areas recognize no national boundaries, nor
do the contaminants to which they are exposed.
As with the Great Lakes, past assumptions of the
limitless potential of these vast water bodies to
absorb chemicals are thwarted by the persistent and
bioaccumulative nature of these contaminants,
focusing and maintaining their presence in biologi-
cal food chains amidst the vast oceanic distances.
The very high levels of POPs found in some marine
mammals, e.g., dolphins, killer whales, and beluga
whales, inevitably lead to questions about their links
to mass strandings and mortality events. The popu-
lar scientific literature contains many stories, ar-
ticles, and opinions suggesting that the concentra-
tions of POPs accumulated by various marine
mammal species are sufficient to be causing adverse
effects. However, these exposure data are not
backed by the rigorous toxicological information
necessary to allow a sound estimate of the actual
impacts of these contaminants. Resolution of these
questions, necessary because POPs levels are in-
deed troubling, is difficult because modern society
treats these highly intelligent and social creatures
with great deference, formalized through the Ma-
rine Mammal Protection Act. As with humans, it is
very difficult to obtain permission to experimentally
dose marine mammals with contaminants. As with
human epidemiology, it is difficult to isolate causal
agents in the presence of viral and bacterial infec-
tive illness, natural toxins (e.g., red tides), food
shortages, predation, and the soup of chemical
contaminants and exposures.
This chapter examines POPs in the marine environ-
ment: their transport and the resulting levels,
trends, and distributions. Examples are provided of
adverse effects on the species most at risk from
POPs—those at the top of the food chain accumu-
lating the greatest concentrations of contaminants.
Field observations of ocean birds, inshore and
offshore, are summarized, demonstrating adverse
reproductive effects both historically and recently.
Research data are then provided summarizing the
evidence for adverse effects on marine mammals.
POPs have spread over the entire surface of the
Earth, as evidenced by their occurrence in the air,
water, and wildlife of the open oceans. The charac-
teristics of POPs that favor their long-range trans-
port are semivolatility, persistence in the atmo-
sphere, and high chemical and biological stability
(see Chapters 7,9). POPs are transported by
runoff and rivers. They are deposited and accumu-
late in marine sediments, particularly in estuaries
and other near-shore areas. The POPs present in
these sediments represent an ongoing source of
contaminants that can be recirculated into the food
chain and accumulated by top predators. Atmos-
pheric transport is also of considerable importance
6-7
-------
Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
to near-shore marine environments where, despite
the influence of terrestrial runoff, short-range trans-
port of contaminated particles may represent a
significant contribution to the total input.
Available information demonstrates that the
oceans, including deep ocean waters, also function
as a major and ultimate sink for POPs (Ballschmiter,
1992; Preston, 1992; Loganathan and Kannan,
1991; 1994; Tanabe et al., 1994; Wania and
Mackay, 1999; Macdonald et al., 2000; Froescheis
et al., 2000). In the late 1970s, the U.S. Environ-
mental Studies Board (1979) estimated that about
50% to 80% of the total PCB residues in the U.S.
environment were present in North Atlantic waters.
It has also been estimated that over 60% of the
world's environmental PCB load is present in open-
ocean waters (Tanabe, 1988).
Analysis of time trends in environmental concentra-
tions is necessary for understanding and managing
the causes and effects of POPs contamination in
marine ecosystems. On the simplest level, time
trend studies indicate the persistence of a substance
by simply watching its rate of decrease with time.
On a more complex level, historical trend studies
can be used to predict future toxic impacts or indi-
cate times when such impacts are no longer signifi-
cant.
Time-trend monitoring programs for POPs exist in
several countries. The International Mussel Watch
Program and the National Status and Trends Pro-
gram of the United States National Oceanic and
Atmospheric Administration (NOAA) are examples
(O'Connor, 1996). Temporal trend studies of
POPs in biota (fish and oysters) from inshore/
coastal aquatic ecosystems have shown clear de-
clines in tissue concentrations following bans on the
use of POPs. Although the concentrations of POPs
in marine biota are generally declining, the rates of
decline are slow (Loganathan and Kannan, 1991,
1994). This slowness results from the long resi-
dence time of POPs in the marine environment and
cycling from sediments and other sources of con-
tamination.
To assess the current status and long-term trends of
POPs in U.S. coastal marine environments,
NOAA's Status and Trend Mussel Watch Program
has been monitoring the coastal waters since
1986 (http://ccma.nos.noaa.gov/NSandT/
New_NSandT.html). Concentrations of POPs have
generally declined in mussels from 154 sites along
the U.S. coast, although some local trends remain
uncertain (O'Connor, 1996, 1998) (Figures 6-1, 6-
2). For fish, the National Benthic Surveillance
Project, a component of NOAA's Status and
Trends Program, has monitored levels from the
West Coast of the United States since 1984 and
found no consistent trend in POPs concentrations
(Brown et al., 1998). These studies have also
documented that fish, mussels, and sediment col-
lected near urbanized coastal areas continue to
contain relatively high concentrations of POPs
(Daskalakis and O'Connor, 1995; O'Connor,
1996; Brown etal., 1998).
Although the concentrations of POPs in sediment
and oysters from coastal areas have declined follow-
ing use restrictions, concentrations in marine mam-
mals have declined only slightly over the past few
decades. Very few studies have examined temporal
trends of POPs using marine mammal tissues. No
significant differences in concentrations of PCBs
and DDT were observed in striped dolphins col-
POPs in US Coastal Mussels '
B
.2
1
c
o>
'~i
&
o
U
OS
"•5
S
^
I
s
&
™
f
0
1
45
40
35
30
25
20
15
10
5
0
-•..„-
| 1985 1990 1995 2000
I Year
Figure 6-1. Decreasing national median concentrations of
contaminants in mussels. Sum values; PCB value divided
by 10.
Source: NOAA
6-2
-------
Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
25
20
15 H
•~ 10 -
5 -•
86
ZPCBs in mussels
90
92
94
t
96
O UISB Siwash
• PVMC Mineral Creek Flats
."- JFCF Cape Flattery (contiguous US)
Figure 6-2. Time trends of PCBs in Alaskan mussels.
Source: NOAA, http://ccma.nos.noaa.gov/NSandT/AKtPCB.html
lected from the western North Pacific Ocean be-
tween 1978-79 and 1986 (Loganathan et al.,
1990) (Figure 6-3). Similarly, fur seals collected
from the northern North Pacific Ocean showed no
decline in concentrations of PCBs during the 1980s
(Tanabe et al., 1994). Six- to ten-year trends in the
concentrations of POPs in the Canadian Arctic
have been examined in female ringed seals and
male narwhal and beluga whales. Concentrations
of DDTs, PCBs, chlordanes, and toxaphene
showed no significant decline in these marine mam-
mals (Muir et al., 1999). In fact, concentrations of
PCBs have increased in minke whales from the
Antarctic since 1984, and the other POPs have
remained at a steady state (Aono et al., 1997).
^,
£
'-J
f.
<"
3
C
1
s
C
40 ,
35
30
25
20
15
10
5
0
1978-79
1986
PCBs
DDTs
Similarly, concentrations of PCBs and chlordanes
in minke whales collected from the North Pacific
Ocean in 1994 were higher than those collected in
1987 (Aono et al., 1997). The current absence of
a reduction in the residue levels of POPs in marine
mammals is consistent with an ongoing redistribu-
tion of POPs up the food chain into long-lived
animals, and emphasizes the long-term potential
toxic impacts of POPs.
POPs reach marine environments by atmospheric
deposition or in terrestrial runoff from rivers. Be-
cause of their relatively low water solubilities, POPs
tend to be strongly bound to particulate matter in
sediments in aquatic ecosystems. Invertebrate
animals living in sediments, such as worms and
shellfish, eat the POPs bound to food particles and
also receive some uptake of POPs directly from
water. Fish and other predators consume these
invertebrates and accumulate a variety of organic
contaminants. POPs biomagnify at each subse-
quent step up the food chain (i.e., reach higher
concentrations in the predator than in its food). In
marine ecosystems, many of these top predators
are birds or marine mammals. A study from the
western North Pacific Ocean has shown the con-
centrations of PCBs and DDTs in striped dolphins
to be 10 million times greater than in surface wa-
ters (Tanabe et al., 1984) (Table 6-1). Although the
concentrations in water or prey items were low,
marine mammals have large pools of fatty tissues,
long lifespan and reduced capacity to metabolize
POPs. As a result, they accumulate high concen-
trations of POPs in their tissues (Tanabe et al.,
1994).
Table 6-1. PCBs and DDTs biomagnify in the North
Pacific Ocean from surface waters through
plankton to marine mammals (Tanabe et al., 1984)
Figure 6-3. POPs concentrations in North Pacific dolphins
(Loganathan et al., 1990).
Concentration (pg/g)
Surface water
Zooplankton
Myctophids
Squid
Striped dolphin
PCBs
0.28
1800
48000
68000
3700000
DDTs
0.14
1700
43000
22000
5200000
6-3
-------
Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
Concentrations in squid in the North Pacific pro-
vide further evidence of the link between environ-
mental pollution and subsequent contamination
high on the food chain in marine mammals and
birds. Hashimoto et al. (1998) measured polychlo-
rinated dioxin and furan levels in predatory squid in
a transect of the North Pacific from Japan to near
the coasts of Canada and the United States, with
additional samples from New Zealand waters (Fig-
ure 6-4). Squid taken from waters near industrial
centers, such as Japan, showed considerably higher
levels of dioxins and furans. The lowest levels were
found in the far South Pacific. The levels of dioxins
and furans in these abundant and relatively short-
lived (1-2 years) predator/prey animals in the
remote North Pacific Ocean provide a clear marker
of the level, extent, and contemporary nature of
POPs contamination. This contamination of the
North Pacific offers potential insights when consid-
ering the sources of elevated POPs levels in alba-
tross on Midway Atoll (see below).
Further POPs transfers can still occur once con-
taminants have reached adult predators at the top
of food chains. POPs are passed on to the next
generation by transfer into the eggs of birds, and
they are passed either directly or via milk into the
progeny of marine mammals. Such transfers of
relatively high concentrations of POPs to the devel-
oping young raise serious questions about the po-
tential effects of these compounds on wildlife popu-
lations.
The global distribution of POPs has been well docu-
mented (Tanabe et al., 1983; Iwata et al., 1993;
Zell and Ballschmiter, 1980). The adverse effects
of POPs on test animals have also been demon-
strated in many studies in laboratories and in the
field. It is the challenge of ecotoxicology to identify
and/or predict the possibility of adverse effects in
wildlife populations based on the known chemical
distributions and known toxic effects. In many
Figure 6-4. Polychlorinated dioxin and furan levels in North Pacific squid (pg/g squid liver)
(Hashimoto et al, 1998).
6-4
-------
Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
cases where discrete chemical applications occur
and adverse effects are clearly evident, such as
acute lethality (e.g., fish kills), it is easy to link the
chemical exposure to the adverse effect. However,
in the case of POPs, many of the adverse effects
are chronic and subtle, and evaluating their rel-
evance to population level effects is difficult. Wild-
life are also more commonly exposed to relatively
low environmental concentrations of POPs, and
these exposures accumulate over long time peri-
ods—whole lifetimes for most animals. Finally,
although most POPs are generally metabolized
slowly, if at all, there are differences in uptake and
elimination that lead to differences in the patterns
of compounds accumulated in different species.
These dissimilarities can result in different contami-
nant exposures to different animals living in the
same environment. In the following sections of this
report, we provide information on the exposures
and effects of POPs on different classes of marine
species.
Figure 6-5. DDT use led to severe impacts on brown
pelicans in the Gulf of Mexico.
Photo: NOAA
The effects of POPs on a number of bird species
have been demonstrated in laboratory and field
studies (Beyer et al., 1996; Blus, 1996; Wiemeyer,
1996). At high concentrations, many POPs can be
acutely toxic. This toxicity is particularly pro-
nounced in pesticides, such as dieldrin, which are
neurotoxins. However, of more concern at current,
relatively low environmental concentrations are the
chronic effects of a number of POPs on the repro-
ductive success of birds. PCBs and dioxins have
been shown to adversely affect the reproductive
success of fish-eating water birds in the Great Lakes
(see Chapter 3). A more historically significant
effect was the near extinction of some bird species
resulting from the adverse effects of DDT residues.
Pelicans (Pelicanus occidentals) in the Gulf of
Mexico were particularly affected by DDT and its
residues (Figure 6-5). These compounds accumu-
lated in the adult birds and caused the production of
abnormally thin eggshells (Figure 6-6). During
incubation in the nest, these thin shells were easily
broken by the relatively clumsy adults. The result
was severe depopulation in this and other species
around the Gulf of Mexico and in other parts of the
United States. On the Pacific coast, daily dis-
charges into the Los Angeles sewer system con-
tained hundreds of pounds of DDT in the 1960s.
This DDT was eventually discharged to the Pacific
Ocean. Coastal waters became contaminated, and
brown pelicans nesting on Anacapa Island more
than 60 miles away suffered near-complete nesting
failure. The colony was littered with broken eggs,
with eggshells averaging 31% (for intact eggs) to
CO
thicknes
1 10 1OO
DDE concentration (ppm)
Figure 6-6. Effect of DDE on eggshell thickness in
pelicans from North America (data from Blus, 1996).
6-5
-------
Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
50% (broken eggs) thinner than normal. In 1969,
1,125 pairs of pelicans were able to fledge only 4
young birds, and in 1970, 727 pairs produced 5
chicks (Anderson et al., 1975).
By the end of 1970, the DDT discharge had been
stopped, leading to a remarkable recovery in repro-
ductive success (Anderson et al., 1975). By 1974,
DDT residues in anchovies, the primary food of the
pelicans, had declined by 97%—from 4.3 ppm to
0.15 ppm. Contamination of pelican eggs by DDT
residues had declined 89%. Eggshell thickness also
improved to 16% (intact eggs) and 34% (broken
eggs) thinner than normal, indicating that by 1974
the abnormal shell thinning caused by DDT and
DDE had been reduced by nearly half. Eggshell
thinning up to about 10% can be tolerated without
affecting reproduction at the population or colony
level. The improvement in reproductive success
was spectacular. In 1974, 1,286 pairs of pelicans
fledged 1,185 young birds. In terms of the number
of young birds raised per nest, the figure rose from
a low of 0.004 in 1969 to 0.922 in 1974—an
improvement in reproductive success of more than
200-fold. These figures confirm the severity of
DDT's effect on the reproduction of carnivorous
birds, and exemplify the remarkable improvement
possible when the release of DDT into the local
environment is stopped.
Although the principal
chemical of concern to
aquatic birds has been
DDT, other organochlo-
rines are usually mea-
sured at the same time.
In North America, much
of the data collected
have been compiled by
the U.S. Geological
Survey and are available
electronically (http-.//
www.pwrc.usgs.gov/
bioeco/). The distribu-
tion of POPs in marine
ecosystems is such that
bird samples analyzed
contain most, if not all,
12.00
1980 1985
Year
Figure 6-7. PCB (red) and DDE (yellow) concentrations in
Canadian coastal birds (double-crested cormorant eggs)
have declined since their peaks in the 1960s and 1970s.
Monitoring sites in the Straits of Georgia (diamonds)
[British Columbia], Bay of Fundy (triangles), and St.
Lawrence estuary (squares). Data from Environment
Canada: www.ee.gc.ca/ind/English/Toxic/default.cfm.
of the "dirty dozen" POPs (Table 6-2). In most
cases, the absence of a particular POP in one of
these species is because it has not been looked for,
not because the POP is not present.
The degree of concern regarding POPs contami-
nants in birds has led to the use of DDE, PCBs, and
dioxin concentrations in double-crested cormorant
eggs as a "National Environmental Indicator" in
Canada. Although many of these initial monitoring
programs focused on the Great Lakes, their use as
indicators has been extended to coastal and mari-
time regions. Concentrations of POPs have de-
clined in maritime regions since their peaks in the
1970s and 1980s, but the rate of decline has
slowed in recent years (Figure 6-7). As concentra-
tions in the environment have decreased, so have
the adverse effects attributable to these compounds.
The decreases in adverse effects are demonstrated
by the recovery of many inshore bird populations
since their historic lows.
Much of the contaminant decline in inshore-living
bird species can be attributed to the large decrease
in inputs to near-shore environments resulting from
the banning, deregistration, and emission reduc-
tions for all of the POPs in North America. How-
ever, now that these chemicals are no longer inten-
tionally produced and
released in the United
States, we cannot expect
to see a continuation of
the dramatic decreases
of the past. Future
declines in near-shore
environments will be
slower and will result
from the global redistri-
bution of the contami-
nants currently present.
Whether ultimately se-
questered to the deep
ocean and sediments, or
transferred to open
waters and accumulated
in animals, this process
can be expected to
continue for a long time
6-6
-------
Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
Table 6-2. POPs detected in North American coastal birds
POPs Pelican <
Aldrina
Chlordane •
DDTb •
Dieldrin •
Dioxins
Endrin •
Heptachlor •
HCB
Mirex •
PCBs • <
Toxaphene •
Cormorant Gull 1
•
•
•
•
•
> •
:agle f
Ubatross
Note: Data from USGS (http://www.pwrc.usgs.
'"In birds, aldrin is rapidly converted to dieldrin.
b"DDT" includes DDT and residues (e.g., DDE).
'ioecq/J; Great Lakes data NOT included.
(Loganathan and Kannan, 1994). Furthermore,
although production and use of POPs such as DDT
has ceased in North America, it continues in other
regions through limited exemptions available under
the Stockholm Convention and in nonsignatory
countries.
Offshore Birds
Recent studies of offshore-living birds have high-
lighted the presence of relatively high concentra-
tions of POPs in remote ocean environments
(Jones et al., 1996; Auman et al., 1997). Several
studies have focused on albatross colonies on Mid-
way Atoll in the North
Pacific Ocean (Figure 6-
8). The atoll, a former
U.S. air base, is located
2,800 miles west of San
Francisco and 2,200
miles east of Japan (see
Figure 6-9). It is situated
close to the northwest-
ern end of the Hawaiian
archipelago. These
studies demonstrate that,
despite living in remote
parts of the North Pacific
Ocean, albatross accu-
mulate concentrations of
POPs similar to those
observed in the North
Figure 6-8. Birds on remote Midway atoll in the north
Pacific are exposed to POPs.
Photo: NASA
American Great Lakes (Figure 6-10). POPs con-
centrations in one albatross species were sufficient
to suggest a significant risk to the reproductive
success of the population.
Populations of albatross species in the North Pacific
are presently on the increase following the cessa-
tion of hunting, which in the early 1900s almost
drove the birds to extinction (McDermond and
Morgan, 1993). Nonbreeding Laysan albatross
(Diomedea immutabilis) mainly frequent the west-
ern Pacific and Asian coasts, while black-footed
albatross (D. nigripes) are more common along the
northeastern Pacific and
North American coasts.
Thus, albatross are useful
indicators of different
sources of marine pollu-
tion in the North Pacific
Ocean. Studies on
similar species in the
South Pacific also pro-
vide useful information
on the global distribution
of POPs in these species
(Jones, 1999). Rela-
tively high concentra-
tions of chlorinated
aromatic compounds,
including PCBs and their
hydroxylated and methyl
6-7
-------
Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
O'OO
Pearl & Herau
• v X Reef
Midway
*
Marc
Reef
,.
North
Pacific
Ocean
s
•«
French
Frigate <
Shoals
*
O'OO 1(
0 SCO km
Oahu
o Maul
%TS/
f-
o
Hawaii
o-oo
Figure 6-9. Midway Atoll is located in the very center of
the North Pacific Ocean at the end of the Hawaiian chain.
Source: UNEP World Conservation Monitoring Centre
sulfone metabolites (Klasson-Wehler et al., 1998),
polychlorinated dibenzo-p-dioxins and
dibenzofurans (PCDD/Fs), and non-ortho-substi-
tuted PCBs were found in fat samples from the
North Pacific populations (Jones et al., 1996).
Lower concentrations were measured in the South
Pacific species (Jones, 1999). Ortho-substituted
PCBs and DDT-related compounds were also re-
ported in plasma samples from these populations,
as were a range of other POPs (Auman et al.,
1997). The concentrations in the black-footed
Figure 6-10. Levels of POPs may be sufficient to decrease
reproduction in albatross from remote Pacific islands.
Photo: John Giesy
albatross are reported as sufficient to cause subtle
adverse effects on reproduction (Auman et al.,
1997; Jones et al., 1996). Although historical data
are scarce, they indicate that the egg-crushing rates
and hatching rates for black-footed albatross be-
tween 1962 and 1964 were comparable to those
of Laysan albatross from 1993 to 1994. However,
the recent rate of cracked eggs in black-footed
albatross, which accumulate greater concentrations
of POPs, is greater than 5%, twice the rate ob-
served in the less contaminated Laysan albatross.
A statistically significant difference was also found
in the hatching rate for the black-footed albatross
compared with the Laysan albatross (Auman et al.,
1997).
The concentrations of some POPs measured in
North Pacific albatross do not differ greatly from
concentrations measured in fish-eating birds in the
North American Great Lakes. For example, pooled
egg samples of black-footed albatross contained 3.8
ppm of total PCBs and 1.8 ppm of DDE, whereas
similar samples from Laysan albatross contained
1.0 ppm PCBs and 0.3 ppm DDE (Auman et al.,
1997). These concentrations can be compared
with concentrations of 9.4 ppm and 6.1 ppm of
total PCBs found in 1988 in the eggs of Great
Lakes Caspian terns and doubled-crested cormo-
rants, respectively (Yamashita et al., 1993). The
finding of elevated POPs concentrations in such a
remote location underscores the global transport of
these chemicals and the limitations of the global
environment to assimilate or "dilute" them to safer
concentrations (Jones et al., 1996).
Marine Mammals
No situation indicates more the global nature of the
POPs problem than the concentrations detected in
marine mammals from around the world. Even
though many marine mammals are not directly
exposed to POPs sources, particularly in the oceans
of the Southern Hemisphere, every marine mam-
mal tissue analyzed contains at least some of the
"dirty dozen" POPs (Colborn and Smolen, 1996).
The life history parameters of many marine mam-
mals result in their accumulating high concentra-
tions of POPs. Marine mammals inhabit aquatic
-------
Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
environments that are the ultimate sinks for many
of these compounds. They have a unique lifestyle
that requires thick layers of blubber to provide
thermal insulation and energy reserves for fasting
periods in their life cycles. These fatty tissues act as
a reservoir for the accumulation of POPs, and also
act as a continual source "resupplying" the rest of
the body with these contaminants when fats are
metabolized. The long lifespan and generally
predatory feeding habits of marine mammals lead
to high levels of POPs in blubber. In addition,
marine mammals appear to be limited in the bio-
chemical processes required to metabolize and
eliminate these chemicals (Tanabe et al., 1988).
Finally, because of the high lipid content of marine
mammal milk, POPs are passed via lactation to the
developing young.
Of the compounds studied in marine mammals,
PCBs appear to accumulate to the greatest concen-
trations in the widest range of species (Table 6-3)
(Tanabe et al., 1983; 1994). Very high POPs
levels have been measured on the U.S. East Coast
in bottlenosed dolphins, reaching 620 and 200
ppm lipid weight for PCB and DDE, respectively, in
mature males (Geraci, 1989). To put these concen-
trations in perspective, U.S. hazardous waste regu-
lations for PCB liquids commence at 50 ppm.
It has been contended that, since 1968, 16 species
of aquatic mammals have experienced population
instability, major stranding episodes, reproductive
impairment, endocrine and immune system distur-
bances, or serious infectious diseases (Colborn and
Smolen, 1996). The authors also suggest that
organochlorine contaminants, particularly PCBs
and DDTs, have caused reproductive and immuno-
logical disorders in aquatic mammals (Colborn and
Smolen, 1996). The presence of high concentra-
tions of PCBs in tissues has also been associated
with
•£- High prevalence of diseases and reduced repro-
ductive capability of the Baltic grey seal
(Halichoerus grypus) and ringed seal (Phoca
hispida) (Olsson et al., 1994)
•;*c Reproductive failure in the Wadden Sea harbor
seal (Phoca vitulina) (Reijnders, 1986) and St.
Lawrence estuary beluga whales (Delphinapterus
leucas) (Martineau et al., 1987)
•;*c Viral infection and mass mortalities of the U.S.
bottlenose dolphin (Tursiops truncatus) (Kuehl et
al., 1991; Lipscomb et al., 1994), Baikal seal
(Phoca sibirica) (Grachev et al., 1989), and
Mediterranean striped dolphin (Stenella
coeruleoalba) (Aguilar and Raga, 1993; Kannan
etal., 1993)
However, unequivocal evidence of a "cause-effect"
linkage between disease development and mass
mortalities in marine mammals is lacking, because
of confounding factors that limit the ability to ex-
trapolate results from field studies.
Compelling evidence that marine mammals can
experience toxic effects comes from data on the
feeding of wild-collected fish from different regions
to confined seals (Reijnders, 1986, 1994; Ross et
al., 1995, 1996, 1997). In the Reijnders study,
two matched groups of captive harbor seals were
maintained in the same location. One group was
fed Baltic Sea herring, the other North Atlantic
herring. The group fed Baltic Sea fish suffered
near-complete reproductive failure, while the group
fed less contaminated Atlantic fish reproduced
normally. Similar impacts were evident on immune
function. However, although the effects of consum-
ing contaminated fish were clear, the specific causal
agent(s) was not. As with field studies, several
confounding factors prevent a conclusive connec-
tion between specific substances and effects in
these studies. These factors include limited sample
sizes, the presence of chemicals other than POPs in
the food fish, the presence of chemical contami-
nants in the "control" diet, as well as general con-
cerns about the nutritional quality and similarity of
the "control" and "exposed" diets. Additional toxic
effects attributed to PCBs and DDT in seals resident
in the Baltic Sea include uterine stenosis and occlu-
sions in ringed seals, skull-bone lesions (osteoporo-
sis) in Baltic gray seals and harbor seals, adrenocor-
tical hyperplasia in Baltic ringed and gray seals,
lowered levels of vitamin A and thyroid hormones
in harbor seals, and lowered immunocompetence in
harbor seals (Reijnders, 1994; Hutchinson and
Simmonds, 1994).
6-9
-------
Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
Table 6-3.
Global PCB distribution in marine mammal populations
PCBs, ug g-1
wet weight,
Species
Bottlenose dolphin
White-sided dolphin
Common dolphin
Pilot whale
Minke whales
Harbour porpoise
Pilot whale
White-sided dolphin
Dall's porpoise
Baird's beaked whales
Bottlenose dolphin
Dusky dolphin
Common dolphin
Pilot whale
Location
East USA
East USA
East USA
East USA
West USA
United Kingdom
United Kingdom
Japan
North Pacific
Japan
South Africa
South of New Zealand
New Zealand
New Zealand
blubber
81.4
50.1
36.5
17
3.3
55.5
36.9
37.6
8.6
3
13.8
1.4
0.75 ->1.0
0.31
Reference
Kuehletal., 1991
Kuehletal., 1991
Kuehletal., 1991
Varanasietal., 1993
Varanasietal., 1993
Morris etal., 1989
Law, 1994
Tanabeetal., 1983
Tanabeetal., 1983
Subramanian et al., 1988
Cockroftetal., 1989
Tanabeetal., 1983
Jones etal., 1999
Schroder, 1998
Much of the controversy over marine mammal
levels of POPs centers on the widely publicized
mortality episodes among bottlenose dolphins
along the Atlantic Coast of North America. Nu-
merous causal agents, or combinations of agents,
have been proposed, but none proven. Apart from
chemical contaminants, exposure to natural marine
toxins has been hypothesized as a possible cause
for the bottlenose dolphin mortality episodes
(Anderson and White, 1989). However, later stud-
ies have indicated that this evidence is circumstan-
tial (Lahvis et al., 1995). Morbillivirus infection
appears to have been at least a contributing factor
in the dolphin mortality (Belfroid et al., 1996).
Lahvis et al. (1995) hypothesized that synthetic
chemicals, specifically AhR-active POPs, render
marine mammals more susceptible to opportunistic
bacterial, viral, and parasitic infection. Debilitating
viruses such as morbillivirus may result in further
immunosuppression, starvation, and death (Lahvis
etal., 1995). Conclusions about causality are
further complicated by the fact that marine mam-
mals are exposed simultaneously to a number of
synthetic halogenated hydrocarbons, many of
which are not quantified or identified. Despite the
high accumulation and possible adverse effects of
PCBs in marine mammals, tissue concentrations of
PCBs that would affect the immune system in ma-
rine mammals have not been established. Similarly,
factors such as population density, migratory move-
ment, habitat disturbance, and climatological factors
have been proposed as playing roles in mass mor-
talities of marine mammals.
Probably the most convincing case for observable
adverse effects of chemical contaminants on
marine mammals is in beluga whales
(Delphinapterus leucas) resident in the Gulf of
St. Lawrence on the U.S.-Canada border (http://
www.meduet.umontreal.ca/seruices/beluga/
beluga_homepage.html). Whales from this popu-
lation have been shown to have a high incidence of
cancers not common in other animals (Figure
6-11), as well as a variety of other lesions (DeGuise
et al., 1994). It is known that these animals accu-
mulate large concentrations of POPs, and it has
been suggested that such accumulation may be a
contributing factor to the observed effects. How-
ever, these animals also accumulate, or are exposed
to, high concentrations of other environmental
pollutants, including polycyclic aromatic hydrocar-
bons (PAHs). Because Ah-receptor active POPs are
tumor promoters, POPs may be a significant con-
tributing factor to the observed cancer occurrence
in these animals. However, because of the limited
amount of quantitative toxicological information
6-70
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Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
Figure 6-11. Intestinal cancer in a beluga whale.
Source: Daniel Martineau, University of Montreal
available about marine mammals (as discussed
above), the relative contribution of POPs to these
effects may never be known.
The above-mentioned field studies indicate an asso-
ciation between POPs and adverse health effects in
marine mammals, although the association is not
conclusive to specific chemicals. Other studies
have focused on the in vivo and in vitro effects of
POPs on marine mammal immune function (De
Guise et al., 1998). These studies have shown
some effects, but it is difficult to relate the effects
observed to a functional deficit in the immune
systems of free-living marine mammals. It has been
suggested that immune suppression as the result of
POPs exposure may be a contributing factor to
marine mammal mass die-offs, such as occurred in
the Mediterranean in 1992 (Aguilar and Raga,
1993).
Toxicological data for the effects of PCBs and
dioxins on marine mammals were recently com-
piled, analyzed, and used to derive toxicity refer-
ence values (TRVs) (Table 6-4) (Kannan et al.,
2000). The TRVs express the best available esti-
mate of the concentrations of chemicals that will
result in adverse effects. Adverse effects can be
increasingly anticipated if the concentration of the
chemical in an animal's tissue rises above the TRV.
The TRVs were derived on the basis of the concen-
tration of chemicals in the food that marine mam-
Table 6-4. Toxicity reference values for marine
mammals (lipid weight basis)
Total PCBs
Food based 10-150 ng/g
Tissue based (blubber) 17,000 ng/g
Source: Kannan etal., 2000.
mals were consuming, or on the concentrations of
these chemicals in the blubber (fat) of the animals.
They were based on studies examining physiologi-
cal effects such as vitamin A depletion, suppression
of natural killer cell activity, and the proliferative
response of lymphocytes to mitogens. Details
regarding derivation of the TRVs are discussed in
Kannan et al. (2000). Because PCBs, dioxins, and
furans are considered to act through the same
mechanism of action, the authors used a weighted
sum of all the exposures to these chemicals, called
"toxicity equivalence" or TEQ.
Using these TRVs, it is possible to conduct a risk
screening for the possibility of adverse effects from
these chemicals in marine mammals. For example,
the blubber concentrations of PCBs in pilot whales
and bottlenose dolphins from the United States
exceed the TRV values (Table 6-5). This suggests
that these animals may be subject to adverse effects
from these chemicals. In contrast to the North
American samples, PCB concentrations in marine
mammals in the Southern Hemisphere are far
lower.
A wide range of POPs have been measured in the
tissues of seals, sea lions, and walruses (collectively
called pinnipeds) (Figure 6-12). These include
chlordanes, heptachlor epoxide, HCB, dieldrin,
toxaphene, PCBs, PCDDs, and PCDFs
(Hutchinson and Simmonds, 1994; Ames and Van
Vleet, 1996). POPs concentrations vary widely
depending on species, location, and feeding pat-
terns. Concentrations in species feeding at low
trophic levels in remote locations, such as walrus in
the Bering Straits (Figure 6-12), remain in the sub-
ppm range (Seagars and Garlich-Miller, 2001).
6-77
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Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
Species
Bottlenose (USA)
Pilot whale (USA)
Dall's porpoise (Pacific)
Pilot whale (NZ)
Baleen whales (NZ)
NZ fur seal (NZ)
Table 6-5. Risk screening of PCBs in marine mammals
Blubber PCB Blubber PCB Exceedance
TRV (ng g-1) PCB (ng g-1)
13,600 81,400
13,600 17,000
13,600 8,600
13,600 310
13,600 12.9
13 600 1,069
Note: TRVs are given on a wet weight basis.
Source: Kannan etal., 2000.
(Ratio PCB/TRV)
6.0
1.25
0.63
0.023
0.0001
0.08
Closer to sources, the relatively high concentrations
of PCBs (85 to 700 ppm) found in harbor seal
blubber, such as in the Wadden Sea, have been
implicated in their mass mortalities and reproduc-
tive impairment (Reijnders, 1986). Similarly, el-
evated exposure of California sea lions to DDT in
the 1970s has been linked to reproductive prob-
lems (Figure 6-13) (DeLong et al., 1973). Califor-
nia sea lions collected in the early 1970s from
coastal California contained a mean DDT concen-
tration of 980 ppm lipid weight in the blubber
(DeLong et al., 1973). A recent study has reported
DDT concentrations of up to 2,900 ppm lipid
weight in the blubber of California sea lions from
the California coast (Kajiwara et al., 2001). DDT
concentrations as high as 169 ppm lipid weight
were also found in the livers of sea otters from
coastal California (Nakata et al., 1998). The occur-
rence of several tens of ppm of PCBs and DDTs
has been reported in harbor seals collected in
1990-1992 (approximately 20 years after the ban
on the use of DDT) from the northeastern United
States (Lake et al., 1995). And the Florida mana-
tee, Trichechus manatus, an endangered species,
has been reported to contain several ppm levels of
PCBs and DDT in blubber (Ames and Van Vleet,
1996).
Adverse effects from POPs on marine mammals
and birds demonstrate the potential for these sub-
stances to affect species in regions far from the
sources of the POPs emissions. At the peak of
DDT use in the United States, many marine bird
species suffered eggshell thinning from DDT, most
particularly the brown pelican which became threat-
Figure 6-12. Pinniped marine mammals, like these walrus,
accumulate POPs to varying degrees depending on
species, location, and feeding patterns.
Photo: NOAA
Figure 6-13. DDT is believed to have caused reproductive
problems in California sea lions in the 1970-80s.
Photo: NOAA
6-72
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Accumulation and Effects of POPs in Marine Ecosystems and Wildlife
ened with extinction. Impacts on birds continue in
some locations, including elevated exposures in
remote reaches of the Pacific Ocean. For marine
mammals, controlled studies of high environmental
pollutant exposures in their food have demon-
strated reproductive impairment and immune
changes. But although many marine species are
exposed to POPs, there are few studies that
"prove" a causal link between specific POPs at
more general environmental levels and adverse
effects in populations or individuals. Nevertheless,
risk evaluations indicate cause for concern. Con-
centrations of POPs in some species and locations
are currently at levels close to those with the poten-
tial to cause adverse effects. Therefore, it can no
longer be assumed that the world's oceans can
dilute these chemicals to "safe" concentrations.
As with the Great Lakes, however, there have been
remarkable recoveries in wildlife populations with
the cessation or reduction of POPs release. POPs
levels in U.S. coastal regions are declining in sedi-
ments and invertebrates. Less evident are reduc-
tions in POPs levels in fish and mammal species,
testifying to the peculiar hazard posed by these
persistent, bioaccumulative, toxic substances and
their ability to remain in the food chain and pass
from generation to generation. Decreases in ma-
rine POPs levels following production and use
controls indicate that regulatory actions can be
successful. However, because of the problems of
global transportation and deposition of these con-
taminants, the desired decreases in global POPs will
not be achieved without global cooperation.
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6-76
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ersistent organic pollutants (POPs) are now
nearly ubiquitous in their distribution over the
Earth. They can be found in remote locations
distant from industrial and agricultural regions, as
well as close to their point of introduction into the
environment. Their propensity for long-range
environmental transport, and the extent of their
distribution, are evident from the levels reported for
the Great Lakes, Alaskan Arctic, and marine eco-
systems. This chapter provides information on
how POPs are transported such long distances by
winds, river and ocean currents, and migratory
animals. The focus is on transport of POPs into
the United States, recognizing that POPs also leave
the United States and have impacts on other coun-
tries through similar processes. Particular attention
is directed to transport in the atmosphere, because
this is the principal medium through which POPs
are distributed globally, either as vapor or on par-
ticles. Examples are provided of the transport of
pollutants between continents, accompanied by an
overview of the atmospheric chemistry of POPs
relating to entrainment, degradation, and deposi-
tion. Methods for tracking the transport of POPs
through the atmosphere are discussed, with ex-
amples provided of the pathways they may take.
This discussion is followed by a summary of infor-
mation on hydrologic movement and transport of
POPs via migratory species.
The behavior of POPs in the environment is com-
plex because they are multimedia chemicals, exist-
ing and exchanging among different compartments
of the environment such as the atmosphere, natu-
ral waterbodies, soil, and sediments, where they
degrade at different rates over time. POPs are also
referred to as semivolatile, meaning they can be
present in more than one phase in the atmos-
phere, either as gases or attached to airborne
particles. The fate and preferential transport of a
POP are strongly determined by its specific physical
chemistry properties, even its particular isomer (i.e.,
same molecular formula but different spatial struc-
ture). The different affinities of POPs for soil par-
ticles, water, and/or lipid molecules, and their rate
of volatilization will determine the pathway each
species or isomer is likely to take in its journey
through the environment. These properties also
influence how far and fast a POP can move from
where it was released into the environment.
Comprehensive monitoring studies support the
conclusion that POPs concentrations are generally
highest in areas where they were once released, or
are still being released. Concentrations generally
decrease with increasing distance from such source
areas. Thus, concentrations are most strongly
dependent on past and present release rates in the
immediate vicinity under investigation, and are also
strongly influenced by regional releases (Kalantzi et
al., 2001). In addition, however, the finding of
surprisingly high concentrations of POPs in polar
areas, particularly the Arctic (Bidleman et al.,
1989; Barrie et al., 1992; Iwata et al., 1993), has
led to an emphasis on the natural processes that
are responsible for this wide-ranging transport
through the global environment. These processes
include:
••'?'• Volatilization of POPs from terrestrial and/or
aquatic surfaces into the atmosphere
•A- Adsorption of POPs vapor onto particles already
entrained in the atmosphere
$ Entrainment from a surface of particles with an
adsorbed POPs layer into the atmosphere
•''''• Transport of air masses throughout a hemi-
sphere by means of persistent, large-scale circu-
lation patterns or by means of episodic rapid
transport processes
7-7
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Long-Range Environmental Transport of POPs
% Photochemistry and interaction of POPs with
free radicals, which can modify and degrade
their chemical form while they are undergoing
atmospheric transport
-$• Deposition by means of wet (e.g., snow, rain,
mist) or dry (e.g., turbulent transport and particle
settling) atmospheric processes onto terrestrial
and aquatic surfaces of POPs that are either in
vapor form or adsorbed onto particles
-#- Transport of POPs in aquatic systems by means
of flowing water (primary surface flows such as
rivers and ocean currents)
-& Transport of POPs in terrestrial and aquatic
ecosystems in the lipids of migrating mammals,
fish, and birds
-$• Deposition of POPs into aquatic sediments
-$• Eventual physical accumulation in receptor loca-
tions, uptake, and bioaccumulation that increases
concentrations in ecosystems and humans
Atmospheric Transport of Pollutants
to the United States
When describing winds in the atmosphere and their
ability to transport trace substances over long dis-
tances (e.g., the equator to the pole or around the
globe) a convenient first approximation is to focus
on their long-term average behavior. This focus is
useful because winds fluctuate in strength and
direction in passing cyclonic and anticyclonic
weather systems, resulting in net displacements
that are relatively small compared with the global
scale. Average, or prevailing, winds blow much
more in east-west directions than in north-south
directions. In midlatitudes, the prevailing winds are
westerly (i.e., from the west), whereas easterly
winds prevail at very high latitudes and in the sub-
tropics (e.g., southern Florida), the latter especially
in spring and summer. In principle, pollutants
released at the surface can travel eastward com-
pletely around the globe at midlatitudes in about 10
days if they are lifted by convective activity (strong
upward air motions that produce clouds) to the
altitude of the jet stream. The average wind speeds
at this level are much stronger than they are near
the surface and can exceed 100 mph in the core of
the jet stream (e.g., Stull, 2000), and the wind
speeds and directions are more constant than they
are near the surface. In contrast to this rapid west-
east transport in the jet stream, it takes several
months for pollutants to spread from equator to
pole. It can take even longer, about a year to a
year and a half, for pollutants to cross the equator
and be evenly distributed over the globe (Warneck,
1988). Mixing caused by small-scale turbulence
normally causes pollutants to disperse so they no
longer form a coherent plume that can be tracked
over long distances. However, on occasion,
plumes of airborne substances remain coherent
and can be tracked for long distances.
Much of the evidence for long-range transport of
airborne gaseous and particulate substances to the
Figure 7-1. Atmospheric transport of Saharcm dust to the
United States.
Source: National Aeronautics and Space Administration, 2001.
7-2
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Long-Range Environmental Transport of POPs
United States focuses on dust or smoke because
these are visible in satellite images or when depos-
ited. Examples include transport of dust from the
Sahel and Sahara Desert in northern Africa, dust
from the Taklamakan and Gobi Deserts in Asia, and
emissions from uncontrolled wildfires in Central
America and southern Mexico. Windblown dust
from individual dust storms in the Sahara Desert has
been observed in satellite images as plumes crossing
the Atlantic Ocean and reaching the southeast coast
of the United States. These storms can last for
several days at a time. A false color satellite image
obtained by NASA's Earth Probe TOMS satellite
showing successive pulses of Saharan dust propagat-
ing eastward across the Atlantic Ocean and reaching
Miami is presented in the top portion of Figure 7-1.
The bottom portion of Figure 7-1 shows a true color
image of the dust cloud over Florida obtained by
NASA's Sea Star satellite on the same day. Analysis
of data obtained by the IMPROVE (Interagency
Monitoring of Protected Visual Environments) net-
work indicates that incursions of Saharan dust into
the continental United States have occurred, on
average, about three times per year. These events
have persisted for about 10 days, principally during
the summer. As might be expected, the frequency
of Saharan dust events is highest in the southeastern
United States. About half are observed only within
the State of Florida, and these are associated with
dense hazes in Miami (see Figure 7-2) such that
African dust is the dominant aerosol constituent in
southern Florida during the summer (Prospero,
1999a). Puerto Rico and the Virgin Islands are
even more strongly affected, as might be expected.
Figure 7-3 shows a false color satellite image of the
passage of a cloud of dust across the Pacific Ocean
to North America. This dust cloud was raised by a
storm in the Gobi and Taklamakan Deserts in April
2001. The highest concentrations of Asian dust
can be seen over the Aleutian Islands. Also shown
in Figure 7-3 is a dust cloud from northern Africa
traveling eastward over the Atlantic Ocean.
Biomass burning for agricultural purposes occurs
normally during the spring of each year in Central
America and southern Mexico. During the spring
of 1998, fires burned uncontrollably because of
abnormally hot and dry conditions associated with
Year
Figure 7-2. Saharan dust episode chronology impacting
Miami, FL.
Source: Prospero, 1999a.
the intense El Nino conditions in 1997-1998.
Figure 7-4 shows the extent of the spread of the
particles emitted by the fires. Concentrations of
particles throughout the central and southeastern
United States were elevated substantially, such that
National Ambient Air Quality Standards for particu-
late matter were exceeded briefly in St. Louis, MO,
and in a number of other cities in the central
United States. The reader should bear in mind that
the atmospheric processes that transport dust or
smoke, as given in the examples above, are also
transporting pollutants, including POPs, either as
vapor or attached to particles. Indeed, micro-
organisms including various fungi and bacteria have
been found attached to North African dust particles
Earth Probe TOMS Aetewol
Figure 7-3. Asian dust storm episode crossing the Pacific
Ocean. NASA.
7-3
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Long-Range Environmental Transport of POPs
Figure 7-4. Smoke from Central American fires. NASA.
in Caribbean air samples (Griffin et al., 2001).
Pollutants, including trace metals that may have
been emitted in North Africa or Europe, have been
found along with North African dust particles in
Miami, FL (Prospero, 1999b).
Rapid transport of pollutants from south to north
can also occur, bringing pollutants from mid-
latitudes to the Arctic in a few days. Many of these
pollutants are relatively short-lived with respect to
degradation in the atmosphere, and are unlikely to
reach the Arctic by the average winds described
above. These transport events occur during winter
and are caused by transient weather events that
result in strong winds directed toward the north in
a narrow current lying typically between a strong
high-pressure region to the east and a low-pressure
system to the west. These weather situations occur
mainly in the former Soviet Union, although they
can also occur in North America. These events
result in the formation of Arctic haze, which regu-
larly affects air quality in Alaska (Shaw and Khalil,
1989).
Although these episodes are infrequent, the
amount of POPs deposited can be substantial,
given the otherwise pristine nature of some of the
receptor locations. For example, Welch et al.
(1991) documented a long-range transport event
that deposited thousands of tonnes of Asian dust
onto a region of the central Canadian Arctic over a
brief (<3-day) period. Analysis of the resulting
brown snow revealed elevated levels of the follow-
ing POPs: PCBs (6.9 ng/g particles), DDT
(4.2 ng/g), toxaphene (3.0 ng/g), HCB (0.7 ng/g),
chlordane (0.6 ng/g), heptachlor, and dieldrin,
along with other organic pollutants such as polycy-
clic aromatic hydrocarbons (PAHs) and hexa-
chlorocyclohexanes (e.g., lindane). The authors
estimated that this single episode may have contrib-
uted up to 10% of the annual loading of DDT to
lakes in this region, and up to l%-3% for the other
measured POPs (depending on loading scenario
assumptions).
Atmospheric Chemistry of POPs
Many POPs, including pesticides and PCBs, are
classified as semivolatile, meaning that they can
exist either as gases or attached to particles. The
relative amounts in the gaseous and particle-associ-
ated forms depend on air temperature. Less vola-
tile POPs tend to partition into surface reservoirs
such as soil, vegetation, rivers, and oceans, where
they associate with organic matter. Warmer tem-
peratures favor their evaporation and residence in
the atmosphere as gases; colder temperatures favor
their deposition to the Earth's surface and their
incorporation into airborne particles. Generally,
warmer temperatures are found close to the Earth's
surface with decreasing latitude (tropics), whereas
colder temperatures are found with increasing
latitude (polar) or altitude. Characteristic tempera-
tures at which half of a particular compound (Ty )
would be present as a gas can be calculated to
indicate the tendency of a POP to remain as a gas
or to attach to a particle (Wania et al., 1998). The
more volatile POPs, such as hexachlorobenzene
(HCB), reach this temperature at -36°C; dieldrin at
-11°C; DDE -2°C; ODD +7°C; DDT +13°C; and
PCBs with at least 6 Cl atoms at about +10°C. As
the number of Cl atoms increases in PCBs, poly-
chlorinated dibenzo-p-dioxins (PCDDs) and furans
(PCDFs), this characteristic temperature also in-
creases, such that molecules with more than 5 Cl
atoms tend to be partitioned mainly onto particles
(Brubaker and Hites, 1998). Compounds such as
mirex and toxaphene (higher molecular weight
fraction of the mixture) are expected to be found
mainly attached to particles, because they have very
7-4
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Long-Range Environmental Transport of POPs
high values of T1/2. Observations show that com-
pounds with the lowest T1/2 tend to have the highest
potential for global scale transport and to remain in
the gas phase even at high latitudes, whereas com-
pounds with the highest values of T1/2 tend to re-
main concentrated close to their sources.
Although the meteorological processes transporting
gases and particles are the same, particles and
gases are subject to different removal processes
that affect the time they remain airborne. Soluble
gases can be removed from the lower atmosphere
by being incorporated into cloud droplets that then
fall out as rain, or by being washed out by falling
raindrops. This limits their lifetime in the atmo-
sphere typically to several days, and also limits the
distances they can travel from their sources. How-
ever, gas-phase POPs are not very soluble and so
their removal by precipitation is not effective. For
example, the removal time for chlordane, dieldrin,
and PCBs can be up to several years by this
mechanism (Atlas and Giam, 1981).
POPs present as atmospheric gases can be de-
stroyed by atmospheric photochemical reactions
involving hydroxyl (OH) radicals in the atmosphere.
Reactions involving other species or photo-
degradation by solar ultraviolet radiation are consid-
ered to be minor loss processes, although data are
sparse. Calculated atmospheric half lives, t1/2 (de-
fined as the time it takes to reduce their concentra-
tions by one-half due to reaction with OH radicals),
for several compounds are shown in Table 7-1,
along with their concentrations in both the gas and
particle phases observed on the shores of the Great
Lakes. As can be seen, t1/2 in the atmosphere
ranges from a couple of days for DDT to a couple
of years for HCB. Notably, the presence of hy-
droxyl radicals is integrally linked to the presence
and level of sunlight. The absence of sunlight in
polar regions for many months of the year effec-
tively eliminates the generation of hydroxyl radicals,
thereby greatly increasing the persistence of atmo-
spheric pollutants that would otherwise be degraded
through this mechanism during daylight.
If POPs become attached to particles, their lifetimes
in the atmosphere are determined by particle re-
moval mechanisms, in addition to reactions involv-
ing hydroxyl radicals or other free radical species in
the particles and photodegradation by solar ultra-
violet radiation. However, the effectiveness of
these processes in particles has not been studied as
well as for the gas phase. The lifetime of particles
in the lower atmosphere is about 1 week with
respect to removal by precipitation. However,
particles above cloud layers can remain airborne
much longer and hence can be transported over
much longer distances. Particles also can be depos-
ited on the Earth's surface when they are trans-
ported downward by turbulent air motions (dry
deposition). Atmospheric lifetimes with respect to
dry deposition depend on particle size, meteorologi-
cal variables near the surface, and microphysical
conditions at the air-surface interface. Lifetimes in
the atmosphere for fine particles (i.e., smaller than
a few micrometers in diameter) with respect to dry
deposition are about a couple of weeks (U.S. EPA,
1996).
Deposition on to the surface does not, however,
mean that a POP has been permanently removed
from the atmosphere. Through a variety of mecha-
nisms, such as microbial activity and photochemical
reactions occurring near the surface of the soil or a
waterbody, POPs that were attached to particles
Table 7-1. Atmospheric concentrations of selected
POPs at IADN" sites and their estimated globally
averaged atmospheric half-lives (t1/2)
Compound
Concentration
Range (pg/m3)b
E Particle
| Gas |
Hexachlorobenzene j 80-130 | 0.1-0.2
Dieldrin j 14-34 j 1.5-3.2
PCB44 | 3.4-14 | 0.09-0.2
DDT ! 3.9-91 i 0.3-3.6
728 d
6.2 d
16 d
2.3d
3 Integrated Atmospheric Deposition Network. IADN consists of five
sites situated on each of the Great Lakes.
b 1 pg = 1 trillionth (1012) of a gram.
'Defined here as the time needed in days to reduce the concentra-
tion of the compound by one-half, using a globally averaged OH
concentration of 1.0 x 106 OH/cm3 (e.g., Krol et al, 1998) and a
mass weighted mean atmospheric temperature of 273°K (0°C).
Source: Hoff et al. (1996) for concentration data.
7-5
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Long-Range Environmental Transport of POPs
may be released and evaporate into the atmo-
sphere. Only through processes such as reaction
with OH radicals in the atmosphere, or biologically
mediated reactions in either soil or natural
waterbodies, is a POP finally gone from the envi-
ronment. These processes are all strongly tem-
perature dependent and proceed faster at higher
temperatures, so that POPs tend to persist longer
at higher latitudes. Lifetimes of most POPs due to
degradation in the marine or terrestrial environ-
ment are estimated to be several years, with degra-
dation occurring more rapidly in tropical than in
polar regions. A degradation product of the origi-
nal POP may also be a POP, or may be toxic in the
environment. For example, dieldrin is formed
during the degradation of aldrin.
Global Distillation of POPs
An intriguing consequence of the combined
semivolatile and persistent nature of POPs is their
potential to volatilize in warm regions, be deposited
in colder ones, and repeat this process until a
location is reached where it is too cold for the POP
to again revolatilize. This process is similar to
industrial distillation processes, such as separating
petroleum products from crude oil. On a planetary
scale, global distillation has been hypothesized to
result in a net transport of POPs from lower lati-
tudes to high latitudes (polar regions) in a series of
jumps (Wania and Mackay, 1996) (Figure 7-5).
Because of the normal decrease of temperature
with increasing latitude, compounds will tend to
condense on surfaces as they are transported
northward by winds associated with passing
weather systems. Various thermodynamic con-
stants can be used to estimate the "stickiness" of
POPs to a surface. One of the most useful is the
octanol-air partition coefficient (KOA ), which is
measurable in the laboratory and relates to the
tendency of a POP to adhere to organic matter in
the soil or natural waterbodies. Values of KOA
range over many orders of magnitude, and the
higher its value the greater the tendency for a POP
to associate with organic matter.
The environmental levels of POPs predicted in
remote locations following global distillation depend
heavily on the physicochemical properties of the
particular POP and the meteorological factors
generating poleward transport. The balance be-
tween POPs concentrations in temperate regions
versus their preferential accumulation toward the
poles is influenced by the following factors:
-& Source proximity: The strength and proximity
of emission sources act as the primary forces
generating pollutant levels. All things being
equal, pollutant concentrations should be greater
at the source and taper off with distance, with
this tapering effect proportional for all pollutants.
But a variety of factors can differentially influence
the transport potential of POPs and their iso-
mers, leading to differential accumulation.
-& Physicochemical properties of different POPs:
As already noted, differences among POPs re-
garding their propensity to exist in the vapor
phase (e.g., KOA, Henry's law constant, vapor
pressure) have an impact on each POP's suscep-
tibility to global distillation and the rate at which
such movement can occur. Differences occur
even within families of POPs, such as among the
209 PCB congeners. Lower chlorinated PCBs,
with two or three chlorines, are more volatile and
amenable to global transport. They tend, how-
ever, to be less persistent than the higher chlori-
nated PCB congeners, somewhat countering
their propensity to preferentially move toward
the poles.
Figure 7-5. Grasshopper effect moving POPs poleward.
Source: Adapted from Wania and Mackay, 1996.
7-6
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Long-Range Environmental Transport of POPs
•£ Temperature dependence o/physicochemica/
properties: Decreased temperatures and re-
duced microbial activity toward the poles in-
crease POPs persistence, thereby inherently
increasing the potential for physical accumula-
tion (see Chapter 9). Decreased temperatures
also alter environmental media partitioning prop-
erties, such as the water-air partition coefficient
(Henry's law constant), increasing the proportion
of a chemical in water compared with the
amount in the adjacent air column. Hexachloro-
cyclohexane (HCH; listed as a POP under the
UNECE-LRTAP POPs Protocol) isomers change
from an aquatic persistence of only a few days in
the tropics to many months or years in Arctic
waters. The Henry's law constant also changes
for the HCHs, increasing the proportion in water
compared with air as the environment cools.
Both of these changes contribute to the higher
absolute levels of HCH in Arctic waters com-
pared with those that had been found close to
the presumed sources in Asia (Iwata et al.,
1993).
Temperature-dependent gradients have been dem-
onstrated on a global or regional scale for several
of the more volatile POPs, although direct evidence
for transfer of POPs from the tropics to the Arctic
remains to be demonstrated (Klecka et al., 2000).
Calamari et al. (1991) reported that HCB concen-
trations in vegetation increased with latitude by
almost a factor of 10 between the tropics and polar
regions, whereas concentrations of the less volatile
DDT were found to be higher in tropical compared
with polar areas by almost a factor of 100.
Simonich and Hites (1995) reported similar results
on the global distribution of 22 organochlorine
compounds in tree bark samples. Here, the distri-
bution of relatively volatile organochlorines, such as
HCB, was dependent on latitude, whereas less
volatile and persistent organochlorines (e.g., en-
dosulfan) remained close to the region of release.
Iwata et al. (1993) measured geographic gradients
for HCH in sea water on a global scale, finding
higher concentrations toward the poles even
though emission sources were in temperate and
tropical regions, predominantly Asia. Sea water
and air concentrations of DDT were substantially
higher near the sources measured in Asia.
Increased altitude and the related decrease in tem-
perature also are associated with increasing levels
of POPs, as demonstrated over a 770 to 3,100 m
altitude gradient in the western Canadian Rocky
Mountains (Blais et al., 1998). Increasing snowfall
at higher altitudes led to a 10-fold increase in depo-
sition with height of less volatile compounds, such
as DDT. For the more volatile organochlorines
(e.g., lower chlorinated PCBs, HCH, and hep-
tachlor epoxide) this increase with altitude was up
to 100-fold, demonstrating enhancement through
cold-condensation effects. The concentration
gradient with altitude is particularly informative
because it was performed in a single geographic
location, making the study less likely to be con-
founded by proximity to sources, which can occur
when there are several geographically dispersed
measurement sites.
Global-scale distillation effects were observed origi-
nally for the heavy isotopes (deuterium, oxygen-18)
compared with the light isotopes (hydrogen and
oxygen-16) of water vapor (Dansgaard, 1953).
Light isotopes are more volatile than their heavier
counterparts. The ratio of light to heavy isotopes
increases with latitude, because of selective conden-
sation of the heavier isotopes in accord with the
Rayleigh distillation formula. For POPs, current
field data relate to a small subset of the most vola-
tile persistent organic substances, consistent with
theoretical predictions (Wania and Mackay, 1996),
i.e., hexachlorobenzene (HCB), polychlorinated
biphenyls (PCBs), hexachlorocyclohexanes (HCH),
and, to a lesser extent, chlordane.
The basis of empirical support for global distillation
comes from the differential increase in accumula-
tion of more volatile PCB congeners (lower chlori-
nated) and HCH isomers (a > y) in higher latitudes.
Many of the factors noted above as influencing
POPs levels in remote locations can be seen affect-
ing, and are consistent with, these measured con-
gener and isomer ratios. Total PCB levels were
found to decline with increasing latitude (consistent
with increasing distance from the source), but the
levels of di- and trichlorobiphenyl stayed relatively
constant with latitude (they are more volatile),
thereby increasing as a proportion of the total PCB
mix (Muir et al., 1996; Ockenden et al., 1998a).
7-7
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Long-Range Environmental Transport of POPs
Notable, too, is the delayed onset of PCB deposi-
tion to sediments in high Arctic lakes compared
with midlatitude and subArctic lakes, providing
further evidence of ongoing global distillation
(Muir et al., 1996). Similar latitude-related ratio
changes favoring more volatile compounds in
northern, colder sites were reported for a-HCH
versus y-HCH (lindane), the former having a higher
Henry's law constant and vapor pressure
(Ockendenetal., 1998b).
Calculating and Modeling Atmospheric
Transport of POPs
The distribution and movement of POPs in the
atmosphere can be calculated by computer model-
ing. The outputs from these models may be used
for making predictions of future trends, for evaluat-
ing the effects of control strategies, and for improv-
ing understanding of the processes controlling the
distribution of POPs. A complete model of the
distribution, ultimate fate, and trends for POPs in
the environment would include modules calculating
the changes of emissions with time; transport by
the atmosphere and oceans; deposition to the
surface and volatilization from the surface; transfers
to rain and snow; and degradation in the atmo-
sphere, oceans, terrestrial waters, and soils. Al-
though information and models are available for
each of these modules for some POPs, a complete
and validated global model has not been published,
principally because of the complexity of the calcula-
tions and the uncertainties in input parameters.
More pragmatically, because of their persistence,
POPs concentrations can be directly measured in
the animal species of interest, reducing the need
for modeling to determine dose and risk. To date,
POPs models have focused on either (1) bulk trans-
fers among different media (i.e., multimedia mod-
els) or (2) simulations of atmospheric movement.
The multimedia models currently include simplified
treatments of transport, whereas the atmospheric
models include highly simplified treatments of the
transfers among the different reservoirs. These two
modeling fields are now merging. Multimedia
models are addressed in Chapter 9 of this report
(see also Klecka et al., 2000). The remainder of
this section focuses on air transport modeling.
There are two basic approaches for calculating the
transport of pollutants in the atmosphere. The first
approach is to calculate trajectories, which are the
three-dimensional paths followed by the center of
mass of an imaginary air parcel, either forward
from a source or backward from a receptor loca-
tion. These are known as Lagrangian models.
The second approach is based on numerical grid
models, which include a number of physical pro-
cesses such as the mixing of air parcels, chemical
transformations, emissions, and deposition to the
surface. These calculations are performed on
individual boxes in a three-dimensional grid matrix,
thereby tracking the dispersion of a pollutant
across this grid (Eulerian models). Both ap-
proaches rely on the use of meteorological data
obtained from ground-based measurements,
weather balloons, and satellites. In some cases,
global climatological model simulations are used
rather than real observations.
Both approaches have advantages and limitations.
The first, or trajectory, approach has the advantage
of simplicity, although it minimizes the physical
processes mentioned above. For example, after a
short time, typically a few days, the air parcels lose
their identity because of mixing. On the other
Figure 7-6. Air movement back trajectories from Tagish,
Yukon, to Asia.
Source: Bailey etal., 2000.
7-t
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Long-Range Environmental Transport of POPs
hand, although the second, or dispersion modeling,
approach includes these important processes, they
are subject to considerable uncertainties. NOAA's
Air Resources Laboratory maintains a Web site
(http://www.arl.noaa.gov/readi;.html) for research-
ers on which it is possible to calculate trajectories
extending either backward or forward for anywhere
in either the Northern or Southern Hemispheres.
Back trajectory models are particularly useful to
ascertain the source of pollutants. For instance,
high levels of a number of POPs, such as a-HCH,
y-HCH, DDT, and chlordane, were found in atmo-
spheric samples at a monitoring site in Tagish,
Yukon, Canada (Bailey et al., 2000). As shown by
the trajectories in Figure 7-6, the pollutants were
associated with long-range transport from Asia,
occurring generally within the previous 5 days.
Coupling emissions data with the trajectory meth-
ods can further inform inferences that POPs ob-
served at monitoring sites came from particular
source regions.
The results of the calculation of a large number of
backward trajectories can be assembled to trace
"transport pathways" leading to a particular moni-
toring site. Several thousand trajectories from
Alaska were calculated backward for 10 days during
the entire year of 1999. Results for 4 months of
the year (January, April, July, and October) are
shown in Figure 7-7 to give an idea of the seasonal
variation in the transport pathways through the
atmosphere (Husar and Schichtel, 2001). The
different-colored shading in Figure 7-7 reflects the
probability that trajectories passed over a given
area before arriving at the Alaska Peninsula Na-
tional Wildlife Refuge in the Aleutian Islands. The
boundaries of each shaded region represent lines of
constant probability. The areas shaded in red have
the highest probability of being traversed by trajec-
tories, whereas those shaded in light blue have a
lower probability. Similar calculations for a number
of receptor sites throughout the United States are
shown in Appendix A. By comparing the locations
of the dust and smoke plumes shown in Figures
7-1, 7-3, and 7-4 to the transport pathways shown
in the figures in Appendix A, it can be seen that the
plumes visible in the satellite images occur within
defined transport pathways. Even though smoke or
dust may not be visible in satellite images, the trans-
port of other airborne compounds, including POPs,
still occurs within these pathways.
Aleutian Islands, AK
January
Figure 7-7. Aleutian 10-day back trajectories for the year 1999. Color shading refers to the likelihood that
trajectories passed over a given area before arriving at the receptor site.
Source: Husar and Schichtel, 2001.
7-9
-------
Long-Range Environmental Transport of POPs
During the springtime, after the winter snows have
melted and before a vegetation cover has appeared,
extensive clouds of yellow dust can be raised from
the Gobi and Taklamakan Deserts (Duce, 1995).
Strong cold fronts originating in Siberia are associ-
ated with strong upward air motions in front of
them as they travel southward. The vertical mo-
tions carry whatever pollutants are found near the
surface upward to the altitude of the jet stream,
where they can be rapidly transported eastward to
North America (Figure 7-3). Siberian cold fronts
can travel all the way to southern China, so a broad
range of pollutants from different regions can be
transported to North America during a single fron-
tal passage. Sinking air over northwestern North
America allows suspended material in the air to be
brought to the surface. It is only during the spring
that the effects of these events are visible in satellite
images. The frontal passages occur at other times,
and may transport pollutants to North America
without raising dust clouds.
Figure 7-8 shows the results of a three-dimen-
sional, chemistry-transport model simulation of the
transport of dust from the Gobi Desert to North
America during the dust storm of April 1998
(Hanna et al., 2000). The "dust" plume shown in
Figure 7-8 was produced by both horizontal and
vertical motions. In general, long-range transport
of pollutants involves movement vertically as well as
horizontally. Events such as those shown in Figure
7-8 result in rapid transport, on the order of a few
days, over transcontinental distances. This simula-
tion included emissions from different points within
Asia and the effects of atmospheric mixing during
the transport of the emissions. Emissions from
different regions of Asia follow their own pathways
to North America, where they affect different ar-
eas. Figure 7-8 also shows that transport does not
terminate abruptly at the coast of North America;
rather, there can be deposition on mountains near
the coast and even further inland. The frequency
of these events and their importance as a transport
mechanism to North America remain to be deter-
mined. The next step will be to include in the
model the chemical losses and multimedia transfers
described above so that the transmission of POPs
and other chemicals during intercontinental trans-
port can be determined.
The results of a three-dimensional, chemistry-
transport model simulation of the global distribu-
tion of hexachlorobenzene (HCB), a long-lived
POP, are shown in Figure 7-9 (Olaguer and Pinto,
2001). The distribution of HCB was calculated
using data for the emissions of HCB and loss by
OH radicals calculated with the model. The areas
of high concentration in Figure 7-9 basically result
from a combination of high emissions and meteo-
rological conditions that favor trapping emissions
close to the surface. The model was able to simu-
late successfully a number of observed features of
the global distribution of HCB, including its ratio
between the Northern and Southern Hemispheres,
lending credence to this approach. Simulations
such as these will permit quantitative testing, by
comparison with observations, of many of the
concepts presented in this chapter.
Figure 7-8. Forward trajectory simulation of dust from the Gobi Desert to North America, April 1998.
Source: Hanna et al., 2000.
7-70
-------
Long-Range Environmental Transport of POPs
POPs Transport In Water
Long-range transport can also occur through hy-
drologic pathways, with POPs entrained on sedi-
ment, in microscopic species, or in solution (for the
more water-soluble compounds). POPs released or
deposited onto terrestrial areas are transported
down rivers to oceans, and then potentially to
remote locations through oceanic currents. POPs
deposited and accumulated on ice in the Arctic can
also be transported into the North Atlantic by ice
floes. The contribution of hydrologic transport to
global POPs pollution has not been quantified,
although it is generally considered to be substan-
tially less than occurs through atmospheric trans-
port of these semivolatile, hydrophobic substances.
Oceanic currents can be wind generated at the
ocean surface or result from water temperature and
density (thermohaline) differences. Wind generated
currents are generally limited to the first 1,000
meters of depth, whereas thermohaline currents
can extend down to the deep sea. Oceanic current
speeds are highly dependent on location. Move-
ment in the Gulf Stream or Kuroshio currents can
be rapid (7-11 km/hr, 4-6 knots) over thousands
of kilometers, whereas within localized gyres (cir-
cling currents) or deep oceanic regions little to no
net water transport may be occurring. The major
surface currents in the North Atlantic Ocean form a
large gyre, or closed clockwise circulation, in which
the Gulf Stream current flows northward along the
east coast of North America to Cape Hatteras, NC,
then travels to the northeast, then southward along
the coast of Europe, and finally westward across
the tropical Atlantic Ocean in the North Equatorial
Current to close the circulation (Figure 7-10).
A similar circulation pattern is found in the North
Pacific Ocean, in which the Kuroshio current flows
northward along the coast of Asia to the southeast
coast of Japan through the East China Sea. Its
width is about 100 km, its speed 6-7 km/hr (3-4
knots), and it transports 30-60 million tons of
water per second (Pickard, 1975). Pacific currents
can transport POPs from Asia to continental Alaska
and its island chains. The transit time around the
HCB Concentration (pg/m3) for July
SON
SON
SON
EQ
30S •
60S
SOS
46
180
120W
60W
60E
120E
180
Figure 7-9. Calculated global distribution of hexachlorobenzene at the earth's surface.
Source: Olaguer and Pinto, 2001.
7-77
-------
Long-Range Environmental Transport of POPs
Bering Sea was estimated in the order of 1 year, as
measured by satellite tracking of drift markers
(Royer and Emery, 1984). Measurements of the
latitudinal distribution of POPs in seawater are
sparse. Concentrations of at least one organochlo-
rine, a-HCH, in seawater were found to increase
with latitude by roughly a factor of 20 on a transect
from the Java Sea to the Beaufort Sea (Wania and
MacKay, 1996; and references therein). This
increase is probably the result of atmospheric depo-
sition. Although computer models of the ocean's
circulation exist and have been coupled with atmo-
spheric models to study problems related to climate
change, they have not yet been applied to prob-
lems of POPs transport.
The ocean can also act as an ultimate sink for
POPs, either through the deposition of dead bio-
logical organisms or via deep-current circulation.
POPs can be concentrated up the marine food
chain, starting with phytoplankton. Some POPs
are transported to deeper layers of the ocean by
settling phytoplankton, or "marine snow." Evi-
dence for this pathway is provided by elevated
concentrations of POPs in marine fish, with higher
concentrations found in deeper living varieties
(Froescheis et al., 2000; Looser et al., 2000).
Sinking water, such as part of the Gulf Stream near
Iceland, also carries with it pollutants such as
POPs. POPs transported to the deep sea by either
of these pathways will probably remain there and
be degraded, because it takes several hundred years
for water in the deep sea to return to the surface
again in a region of upwelling.
POPs transport through migratory species is also
considered a potential source of contaminant move-
ment under the Stockholm Convention. Evaluation
of this mechanism differs from the previous assess-
ments of atmospheric and hydrologic transport,
because POPs transported through migratory spe-
cies are often focused on a localized region (lakes,
nesting sites) or injected directly into the food sup-
ply. Through this means, the POPs concentration
in lipid is maintained, dilution is prevented or mini-
mized, and the POPs are potentially targeted at a
135 VYV 9C'W
: \y,
4* - r ^ ' H'
-------
Long-Range Environmental Transport of POPs
receptor animal species. This can be viewed as
more of a stiletto approach, compared with the
blunderbuss of atmospheric transport.
The bulk amount of POPs transported long dis-
tances by migratory birds, fish, and/or marine
mammals is highly uncertain, and estimates are not
available (van de Meent et al., 2001). However, it
has been calculated that the POPs loading from
spawning and dying salmon swimming to localized
lakes in Alaska is greater than air deposition levels
(Ewald et al., 1998). POPs may also be trans-
ported by migratory birds to remote rookeries, and
from there be transferred to resident species. Most
importantly for high trophic predators and human
risks, the oceanic movement of some fish and
marine mammals can transfer the POPs loads
obtained throughout this migratory journey directly
to the end predator.
Monitoring and Modeling POPs Trends
Atmospheric monitoring and modeling provide re-
assurance that efforts on POPs can be, and are,
effective in regions such as the Great Lakes. On
the basis of data collected by the Integrated Atmo-
spheric Deposition Network (IADN; www.epa.gov/
glnpo/iadn/), trends in concentrations of a number
of key POPs can be calculated and extrapolated to
give approximate dates when atmospheric concen-
trations will be beneath minimum detection limits of
the measurement techniques used (i.e., "virtual
elimination"; Cortes et al., 1998). Results of these
extrapolations are shown in Figure 7-11. Atmo-
spheric levels of DDT and DDD are predicted to be
the first below detection limits, disappearing at all
sites by about 2010. HCB will remain in the atmo-
sphere the longest of all the compounds consid-
ered, mainly because of its continued production as
a byproduct. Overall, though, these data suggest
that most of the compounds will disappear from the
atmosphere of the Great Lakes by the middle of
this century.
Acknowledgments
The help of Dave Leonhard and Dianne Caudill in
producing the figures is gratefully acknowledged.
Dr. Rudolf Husar kindly supplied the calculations of
2010
2040
2070
2100
Virtual Elimination Date
Figure 7-11. IADN virtual elimination dates for
atmospheric concentrations in the Great Lakes region.
Virtual elimination date estimates assume no significant
new sources.
Source: Cortes et al., 1998.
transport pathways used here. Helpful comments
by colleagues including Drs. Eduardo Olaguer,
Elliott Atlas, and Leonard Barrie are also gratefully
acknowledged.
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7-75
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reaties are guided by past experiences, negoti-
ated in the present, and look to a better future.
For the Stockholm Convention, a fundamental
consideration is what the future might hold in
decades to come in the absence of action. As with
the accumulation of POPs in the environment, the
passage of time necessitates thinking beyond the
present day. What will be future sources and levels
of POPs emissions, and could the Stockholm Con-
vention affect these emissions? This chapter in-
forms these considerations by summarizing the
results of existing demographic and economic
futures forecasts. The models demonstrate that
future POPs source regions will likely be different
from current ones, and that very large regional
growth rates in human populations and economic
and industrial activity could drive POPs emissions in
the absence of controls.
The futures modeling scenarios to be presented
were developed and reviewed as part of the Inter-
governmental Panel on Climate Change (IPCC)
research program. Rather than estimate specific
POPs emissions, the models focus on the growth in
current economic activities in which POPs are used
or emitted under current production and use pat-
terns. The intent is to indicate the general pattern
of economic growth and important sectoral com-
ponents of these activities. Results are presented
for the Special Report on Emission Scenarios
(SRES) B2 scenario, one of the four basic classes
of scenarios developed for the recent IPCC report
(IPCC, 2000). The SRES B2 scenario was selected
because it falls roughly in the center of future pro-
jections of population and economic activity, yet is
relatively optimistic about the future of presently
developing countries and does not contain major
new policy initiatives. Most of the data presented
come from the MiniCAM (Edmonds, 1985, 1996)
version of the B2 scenario developed and submit-
ted to the Special Report by the Global Change
Group (GCG) at Battelle Pacific Northwestern
National Laboratories (PNNL) (IPCC, 2000; pp.
566-570), or, in some noted instances, from recent
revisions based on model improvements. Results
from the Second Generation Model (SGM), the
GCG's larger and more detailed emissions model
(Edmonds et al., 1995), were used for some of the
detailed sectoral results. The SGM model run used
for these results largely reproduces the aggregate
population and economic activity patterns of the
PNNL MiniCAM B2 model, acting as an internal
validity check of the results expected in a "B2
future world."
The SRES B2 projection is commonly considered
the "business as usual" scenario. Such a scenario
assumes a continuation of past trends in popula-
tion, technologies, and industrial output, with no
major shifts in government policy. This forecast is
the basis for all U.S. Administration energy and
climate change analyses. For the forecasts in-
cluded in this chapter, U.S. population and gross
domestic product (GDP) trajectories have been
modified from the SRES (IPCC, 2000) report to
track the most recent Annual Energy Outlook
forecast (U.S. DOE, 2000). Results are modeled
to the year 2050. It is important to recognize
that population, GDP, and the nature and struc-
ture of economic activity can be quite different
from the values given here. Using B2 as a rep-
resentative case should not be interpreted to
mean that this is the most likely situation. It is
used because it provides a good qualitative sense
of how activities leading to POPs emissions
might grow in the absence of additional control
strategies.
The results of the B2 model runs are presented
under two basic categories: general growth and
sector-specific results. The general growth cate-
gories are factors such as population, economic,
3-1
-------
Contemplating POPs and the Future
and industrial growth that act as potential pollu-
tion drivers. These general growth drivers are
not necessarily linearly associated with environ-
mental pollution, as economic growth and pros-
perity have also led to enhanced pollution aware-
ness and the means to combat it. The
sector-specific forecasts have been selected for
their potential relevance to one or more of the
listed POPs in developing countries. For in-
stance, if the use of chlordane and other POPs
termiticides is continued, the emission levels
would likely relate to such factors as housing
starts. Byproduct POPs emissions have come
from municipal and hospital waste incineration,
open burning of wastes, chlorine bleaching of
pulp and paper, and iron and steel sintering,
among others. In the absence of control tech-
nologies as economies develop, future byproduct
emissions from these sources could reasonably be
expected to increase, with the sectoral projec-
tions acting as a proxy for these emission in-
creases.
General Worldwide Growth Projections
Population Growth
Human population growth is central to all pollu-
tion scenarios. All of the POPs were either de-
veloped and produced to satisfy contemporary
human needs, or are the byproducts of human
activities. Figures 8-1 and 8-2 provide forecasts
of human population growth rates and projected
levels by region. The population forecast used
here closely mirrors the most recent United Na-
1.60%-
1.40%
1.20%-
1.00%-
0.80%-
0.60%-
0.40%-
0.20%
0.00%-
/
/
/
/
/
/
/
/
World Population Growth Rate
e
-
c
1995
-
-
t—.
2005
-
Pop Growth 1
-
2015
-
=?
-
C
2025
-
c
ffl f=n
2035 2045
Regional Populations
9000
_. 700°
I 6000
1 5000
I 1000
I- 3000
DROW
DAsia
1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050
Figure 8-1. Projected declining annual rates of world
population growth.
Figure 8-2. Projected world population levels, by region.
ROW, rest of world; EEFSU, Eastern Europe Former
Soviet Union; OECD, Organization for Economic
Cooperation and Development.
tions median forecast (Population Division;
United Nations, 2000) that the total world popu-
lation will reach 9.3 billion by 2050. As evident
in Figure 8-1, the projected global population
growth rate is decelerating, although it remains
uncertain how long this trend will continue. The
global average rate conceals large variations
across regions, with the Rest of the World (ROW)
region continuing to grow rapidly, whereas the
population is declining in all Organization for
Economic Cooperation and Development
(OECD) countries, except the United States.
The projection of total world population (Figure
8-2) demonstrates that population increases will
likely be concentrated in three areas, the largest
being the rest of the world category, comprised
principally of Latin America and Africa in this
graph. China and India are the other two large
contributors, with the Chinese population esti-
mated to have peaked by 2030 and in a slow
decline by 2050. The Indian population, in
contrast, continues to grow, although not as
rapidly as Africa and Latin America. The cur-
rent group of developed countries will constitute
only about 10% of the world population by 2050.
The global population will be much older on
average than it is today, with the average age
increasing from 26 to 36 years (United Nations,
2000).
3-2
-------
Contemplating POPs and the Future
Economic Activity
In contrast to the —50% growth in population,
global economic activity is projected to increase
fourfold, from US$22 trillion in 1990 to $88
trillion in 2050 (in 1990 U.S. dollar equivalents).
Average per capita income will more than
double. The overall pattern of economic activity
shows a large shift from its current focus in North
America and Europe to Asia, Africa, and Latin
America (Figure 8-3). Half the growth in eco-
nomic output will occur in these areas, with their
share of economic activity projected to rise from
16% to 41% over the half-century. The growth
in ROW GDP is especially large, reflecting a
combination of rapid population growth and
increase in per capita income from just over
$1,000 per capita to about $4,500 per capita.
Because these areas currently have quite low per
capita income levels, it is anticipated that much
of this growth will go to the provision of essential
physical commodities, such as infrastructure and
appliances. In contrast, the economic growth in
the currently developed economies will likely be
focused in areas such as services, which are less
intensive users of such inputs as energy and
chemicals. The likelihood exists, therefore, that
much of the growth in potential POPs-producing
activities could occur in developing countries.
Regional and Global GDP
Figure 8-3. Projected growth in worldwide gross domestic
product (GDP). ROW, rest of world; EEFSU, Eastern
Europe Former Soviet Union; OECD, Organization for
Economic Cooperation and Development.
Regional Agricultural Output
1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050
Figure 8-4. Projected increases in worldwide agricultural
output. ROW, rest of world; EEFSU, Eastern Europe
Former Soviet Union; OECD, Organization for Economic
Cooperation and Development.
Agricultural Output
The pattern of agricultural production shows a
similar, although less pronounced, shift from
developed to developing countries (Figure 8-4).
The models predict a nearly 21/2-fold increase in
agricultural output worldwide, with the OECD
share falling from about two-thirds to just over
one-half. Data from similar scenarios in the
SRES database (CIESIN, 2001) suggest that this
growth in output will occur with only minimal
growth in land area allocated to agricultural pro-
duction, implying a significant increase in inten-
sity of production and a corresponding increase
in agricultural chemical use.
Total Electricity Consumption
250
1990
2005
2020
2035
2050
Figure 8-5. Projected growth in worldwide electricity
consumption. ROW, rest of world; EEFSU, Eastern
Europe Former Soviet Union; OECD, Organization for
Economic Cooperation and Development.
3-3
-------
Contemplating POPs and the Future
Energy Consumption
Total energy consumption and associated gas-
eous and particulate emissions serve as an addi-
tional proxy for economic development. Total
electricity consumption is predicted to grow by
more than a factor of six, rising from 35 Ej
(exa-, 1018 joules) in 1990 to 233 Ej in 2050
(Figure 8-5). The proportion of electricity con-
sumed outside OECD countries also rises rapidly,
from 38% in 1990 to 79% in 2050. Although
the fraction of electricity generated by fossil fuel
inputs declines slightly during the 1990-2050
period (60% to 52%), the strong growth in elec-
Regional Emissions of CQ, framEnergy Sector
1990
2005
2020
2035
2050
Figure 8-6. Projected worldwide emissions of carbon
dioxide from the energy sector. ROW, rest of world;
EEFSU, Eastern Europe Former Soviet Union; OECD,
Organization for Economic Cooperation and
Development.
Projected Sulfur Emissions
80
>. 70
I 60
(0
c
•55 50
CO
Q)
I 30
1 20
10 •-
1990
2005
2020
2035
2050
Figure 8-7. Projected worldwide declines in sulfur
emissions as a result of improved technologies. ROW,
rest of world; EEFSU, Eastern Europe Former Soviet
Union; OECD, Organization for Economic Cooperation
and Development.
tricity demand is predicted to increase global
CO2 emissions from 5.6 billion tonnes to 12.1
billion tonnes (Figure 8-6), with the developing-
country proportion rising from 59% to 77%.
Sulfur emissions provide an important
counterexample to the general upward trend in
emissions and economic activity. Despite the
rapid growth in electricity use and coal-fired
plants, sulfur emissions are expected to decline
sharply over the next half-century (Figure 8-7).
This decline results from the development and
application of control technologies, a situation
somewhat analogous to the potential for POPs
byproduct controls under the Stockholm
Convention.
Sector-Specific Growth Projections
The preceding demographic and economic factors
act as general—but nonspecific—drivers of pollu-
tion and POPs levels. In some instances, specific
sector models are available that more closely link
economic activity with one or more POPs. Two
such examples are summarized below: housing
starts and termiticide use; and municipal waste
generation and selected industrial production cat-
egories and potential byproduct emissions. Al-
though the links between these sectoral projections
and potential POPs releases are indicated, no
attempt is made to perform further modeling be-
yond the existing projections.
Housing Starts and Termite Control
Of the POPs pesticides, chlordane (along with
heptachlor and mirex) continues to be used for
household termite control in both wood and brick
construction in a number of developing countries.
Chlordane is relatively cheap and provides long-
lasting termite control in the soil beneath and
around houses, but ultimately may be released
into the environment and transported far from its
site of application. Alternative non-POPs pesti-
cides, physical barriers, and construction tech-
niques are available for termite control, but the
sheer persistence and toxicity of chlordane is still
considered by some to be a substantial asset in
the struggle against termites, especially in the
8-4
-------
Contemplating POPs and the Future
tropics. With cessation of production in the
United States, China commenced chlordane
manufacture and has requested an exemption for
production and use as a termiticide in buildings
and dams. Several other countries have re-
quested use exemptions for chlordane as a
termiticide (UNEP, 2001).
Sector-specific projections indicate that growth in
households worldwide will be substantial, because
of the overall growth in population and as that
population ages and becomes more urban. The
estimates provided here reflect only the aging and
population growth components, but not the im-
pacts of urbanization. They are based on age-
specific head of household rates from MacKellar
et al. (1995) (Figure 8-8). Total annual new
household formation is projected to reach nearly
35 million by 2015 and then slowly decline to
below 25 million annually by 2050. Almost all of
this new household formation and related con-
struction will occur in the developing world.
Municipal Waste Generation
and POPs Byproducts
Polychlorinated dioxins and furans are principally
formed and released from the poor or uncon-
trolled combustion of municipal and hospital
wastes, particularly open burning, resulting from
a combination of poor burn parameters, organic
matter, chlorine, and metal catalysts. Although
data quality issues exist for projections of solid
waste generation, enough is known to indicate
that the solid waste stream will grow rapidly over
the next half-century. A recent World Bank
report suggests two drivers for this growth: an
increase in urban populations and an increase in
Annual Household Formation by Region
Figure 8-8. Projected worldwide new household
formation. ROW, rest of world; EEFSU, Eastern Europe
Former Soviet Union; OECD, Organization for Economic
Cooperation and Development.
the income of urban dwellers. Urban dwellers
generate several times more waste than do
rural dwellers (World Bank, 1999) (Table 8-1).
Wealthy urban dwellers generate about 2.5 times
more waste per capita than do poor urban dwell-
ers. Over just 25 years, Asia is predicted to
move from about 30% to more than 50% urban
dwellers. Forecasts suggest that the rest of the
developing world will follow a similar pattern.
The World Bank study estimates an overall
growth in municipal solid waste of 2.4-fold by
2025, to a total of two-thirds of a billion tons
annually in Asia alone. The waste stream is
forecast to become more combustible and or-
ganic in composition, making incineration an
increasingly attractive option, while landfills be-
come more scarce.
Table 8-1. Recent and projected municipal solid waste (MSW) generation per capita in Asia
1990
Region
Low-income Asia
Middle-income Asia
High-income Asia
GNP/
Capita
490
1,410
30,990
% Urban
27.8
37.6
79.5
MSW/
Capita
0.64 kg
0.73kg
1.64kg
2025
GNP/
Capita
1,050
3,390
41,140
% Urban
48.8
61.1
88.2
MSW/
Capita
0.77 kg
1.17kg
2.17kg
3-5
-------
Contemplating POPs and the Future
Industrial Processes and POPs Byproducts
Other sources of polychlorinated dioxin and furan
byproducts listed in the Stockholm Convention
include elemental chlorine bleaching of pulp and
paper, iron ore sintering, and secondary metals
production, such as poorly performed recycling
through incineration of copper and other metal-
containing items. Projected production increases
under these sectors are shown for a subsection of
regions where data are available. The extent to
which production increases translate to POPs
emission increases is highly dependent on the
development and use of pollution prevention and
control practices.
The model results for wood production, relevant
to the extent they can be considered a proxy for
pulp and paper manufacture, demonstrate an
approximate fourfold increase over 50 years,
reasonably uniform across all regions (Figure 8-9).
Total steel production, a proxy for iron ore sinter-
ing, is projected to increase threefold by 2050 in
the same five regions (Figure 8-10). China is
projected to be the largest steel producer by the
end of this period, with Japan and the United
States remaining significant producers. Nonfer-
rous metals are a much smaller part of produc-
tion, and model results are available for only four
regions. Absent data for China, the production
picture for the four other regions remains domi-
nated by the United States and Japan, with
somewhat slower growth than for steel (graph not
shown).
Wood Products Production
1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050
Iron and Steel production
1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050
Figure 8-10. Projected iron and steel production from
selected countries.
Figure 8-9. Projected wood products production from
selected countries.
It bears noting that other POPs also have con-
tinuing connections to demographic and eco-
nomic drivers in the absence of additional con-
trols. DDT use continues for malaria vector
control in the tropics, where projected increases
in human populations are accompanied by a
possible expansion of the range of the vector.
Country-specific exemptions exist under the
Stockholm Convention for limited continued use
of the pesticides mirex, heptachlor, aldrin, and
dieldrin, principally for termite, ant, and locust
control. Hexachlorobenzene production contin-
ues as an industrial intermediate and byproduct
of chemical manufacture and incineration, and
PCBs remain worldwide awaiting equipment
retirement and destruction or environmentally
sound disposal. Agricultural use of a number of
POPs also continues in some countries contrary
to national laws, and the potential exists for
future POPs development for agricultural or in-
dustrial purposes in the absence of an imple-
mented Stockholm Convention.
Summary
There will be large increases in the scale of world-
wide economic activity over the next half-century,
with overall economic activity predicted to increase
about fourfold. Individual economic and end-use
activities that either use or emit POPs can increase
by more or less than this overall growth rate, de-
pending on the specifics of the activity and its
8-6
-------
Contemplating POPs and the Future
growth. Except for activities directly linked to
population increases, such as new households or
populations in mosquito-prone areas, none of the
sectors is expected to grow by less than a factor
of two, some growing by as much as sixfold.
The Special Report on Emission Scenarios
(IPCC, 2000) considers many scenarios other
than those presented here, some with much
higher levels of per capita incomes and lower
populations, others with lower levels of economic
well-being and higher populations. Yet all of
these projections share a future of much higher
total economic activity, and hence of potential
uses and emissions of POPs in the absence of
active control policies.
Center for International Earth Science Information Net-
work (CIESIN). 2001. http://sres.ciesin.org/.
Edmonds J, Pitcher HM, Barns D, Baron R, Wise MA.
1995. Modeling future greenhouse gas emissions: the
second generation model description. In: Modelling
Global Change. Tokyo: United Nations University Press,
October 1995.
Edmonds J, Reilly J. 1985. Global Energy: Assessing
the Future. New York: Oxford University Press, p. 317.
Edmonds J, Wise M. 1996. Stabilizing atmospheric
CO2: rethinking the emissions problem. In: An Eco-
nomic Perspective on Global Climate Change. Washing-
ton, DC: American Council for Capital Formation.
Intergovernmental Panel on Climate Change. 2000.
Special Report on Emissions Scenarios. Cambridge
University Press.
MacKellar FL, Lutz W, Prinz C, Goujon A. 1995. Popu-
lation, households, and CO2 emissions. Pop Dev Rev
21(4):849-865.
U.S. Department of Energy (U.S. DOE). 2000. Annual
Energy Outlook 2001. DOE/EIA-0383(2001), Decem-
ber 2000. http://www.eia.doe.gov/oiaf/aeo/mdex.html.
United Nations. 2000. Population Division, Department
of Economic and Social Affairs. World Population Pros-
pects, The 2000 Revision, Highlights. February 2000.
http://www.un.org/esa/population/wpp2000h.pdf.
United Nations Environment Programme. 2001. Re-
vised list of requests for specific exemptions in Annex A
and Annex B and acceptable purposes in Annex B
received by the secretariat prior to commencement of
the Conference of Plenipotentiaries on 22 May 2001.
UNEP/POPs/CONF/INF/1/Rev 3. 14 June 2001.
World Bank. 1999. What A Waste: Solid Waste Man-
agement in Asia, http://www.worldbank.org/html/fpd/
u rba n/publica t/was te. pdf.
3-7
-------
. eflecting the dynamic societal, scientific, and
industrial time in which we live, the Stockholm
Convention anticipates change through the ability
to list additional persistent organic pollutants
(POPs) as new science becomes available. The
United Nations Environment Programme (UNEP)
mandate for the POPs negotiation had limited
initial consideration to the twelve substances or
substance groups. By doing so, negotiators were
able to focus on developing generic procedures for
addressing POPs, based on the "dirty dozen,"
rather than digressing into potentially controversial
discussions over additional chemicals that might be
added. The mandate emphasized, however, "the
need to develop science-based criteria and a proce-
dure for identifying additional persistent organic
pollutants as candidates for future international
action." This task was undertaken by technical
experts at criteria expert group (CEG) meetings in
Bangkok (1998) and Vienna (1999), and during
subsequent negotiations. The resulting process and
criteria for the addition of chemicals are codified in
Article 8 and Annexes D, E, and F of the
Stockholm Convention, respectively
(www.unep.ch). This chapter summarizes the
technical foundation and science-policy basis con-
sidered in developing these criteria and procedures,
accompanied by contemporary advances in science
from the published literature.
Noteworthy in technical discussions on the addition
of chemicals was the speed with which consensus
was reached among scientists at the CEG meet-
ings. Numerous factors contributed to this consen-
sus, among them: criteria precedents, e.g.,
UNECE-LRTAP; the "scientific method" based on
the provision of data to support opinions; and
external academic, industry, and nongovernmental
organization (NGO) involvement. Of paramount
importance, though, was the inexorable weight of
evidence gathered and widespread action already
taken against POPs. Only rarely now do U.S.
industry and pesticide manufacturers seek to
commercialize a substance with POPs character-
istics, particularly if there is the possibility of a
dispersive use. This reticence to develop POP/
PBT (persistent, bioaccumulative, toxic) chemi-
cals predates the domestic PBT guidelines and
actions, and can be seen as responsive to techni-
cal, economic, and environmental concerns about
the impacts of POPs.
Over the decades, the academic community has
also provided scientific input from research on
the ecological and human health problems stem-
ming from POPs. Input from research scientists
to deliberations in the United States and Canada
on the UNEP POPs negotiation was consolidated
through the 1998 SETAC Pellston Workshop on
the "Evaluation of Persistence and Long-Range
Transport of Organic Chemicals in the Environ-
ment." The report of this workshop (Klecka et
al., 2000) provides an excellent technical sum-
mary on persistence and long-range transport.
The weight of evidence against POPs is also sup-
ported by the number of previous domestic, bilat-
eral, and international technical reviews and policy
interventions to identify and address this group of
chemicals. The screening criteria used in many of
the domestic actions and international POPs/
PBT agreements are listed in Table 9-1. The
differences in screening criteria values should be
interpreted in light of the geopolitical scope of
each initiative. The broader the geographic
range, the higher the screening criteria values
because the more problematic a substance must
be to cause transboundary effects at this dis-
tance. Integral to interpreting the international
POPs screening values is the recognition that
they complement domestic initiatives. Most
POPs contamination occurs close to the site of
9-7
-------
Addition of Chemicals
Table 9-1. National and international screening criteria for POPs
Stockholm
Convention
2QQ\*
UNECE-LRTAP
1998*
NAAEC-CEC
1997
Canada TSMP
1995
US KPA 1998
TSCA new
chemicals
PBT policy - han
pending lestiog
US EPA 1998
TSCA oew
chemicals
PBT policy -
release conimU
UC 1993
immediate action
IIC 1993 inilial
screen
CMA PTB
policy 1996
Long-Rmige Transport*
Renwle
Meiswsmeiits
•
•
•
•
Vapor Pressure
Pascals
or
-------
Addition of Chemicals
3. Risk management/socioeconomic
considerations (process Article 8-7; Annex
F): Subsequent to an affirmative finding from
the risk profile, management options are
evaluated for the proposed substance, taking
into consideration technical and socio-
economic considerations.
4. Recommendation to, and decision by, the
Conference of the Parties (COP; process
Article 8-9): Based on the risk profile and
management options, a technical
recommendation is made to the COP whether
a chemical should be considered for listing in
Annexes A, B, and/or C and what control
measures should be invoked. Ultimate
decisionmaking rests with the COP. Set-aside
and review procedures are detailed in Articles
8-5 and 8-8.
5. Ratification of amendments (Article 22-4):
Each Party to the Stockholm Convention may
opt to review its concurrence with the
addition of each new chemical to the
Annexes. For the United States, entry into
force for additional chemicals is likely to
require an affirmative statement agreeing to
be bound by this addition, although domestic
implementation details have not been
finalized.
The basic process for adding POPs chemicals is
consistent across a range of international agree-
ments (UNECE-LRTAP, 1998; NAAEC, 1998) and
with the conclusions of scientific bodies charged
with developing such procedures (CEG, 1998;
Klecka et al., 2000). The process and criteria
recognize the complexity of real world environ-
ments, and the necessary balance between codi-
fying indicative guidance criteria versus flexibility
and the need for expert judgment. Earth's envi-
ronments vary from steamy, microbe-rich jungles
to frozen waters and anerobic sediments, all of
which may play a part in the environmental fate
of a POP. Reversing this scenario, the many and
varied physico-chemical properties of the indi-
vidual POPs influence how they pass through,
accumulate, and sequester in and over the Earth.
This section summarizes the technical consider-
ations in evaluating a substance for inclusion as a
POP. Additional details on screening criteria
development can be obtained from Rodan et al.
(1999); on persistence, transport, and modeling
from Klecka et al. (2000); and on bioaccu-
mulation from the Great Lakes Water Quality
Criteria support documents (U.S. EPA, 1995).
Annex D of the Stockholm Convention provides
a hierarchical structure for the initial screening of
POPs candidates. This screening requires satisfying
all four criteria categories of (1) persistence, (2)
bioaccumulation, (3) long-range environmental
transport, and (4) adverse effects (toxicity). Flexibil-
ity and expert judgment are stipulated, however,
wherein a low value for one criterion should be
weighed against values for other criteria and envi-
ronmental fate and monitoring considerations.
Persistence is the ability of a substance to remain
in the environment. It is measured as either a
half-life (time for half the amount of substance to
degrade) or a residence time (average time for a
molecule to remain in that environment = half-
life - 0.693). These measurement units as-
sume first-order decay kinetics, which is con-
sidered a reasonable assumption at the
screening stage (Klecka et al., 2000). As de-
tailed in Table 9-1, persistence screening val-
ues for the Stockholm Convention and UN-
ECE-LRTAP POPs Protocol are set at a
half-life of 2 months in water or 6 months in
soil or sediment, or evidence that the chemical
is otherwise sufficiently persistent to justify its
consideration. The numerical values are tacitly
based on temperate climates, where much of
the research has taken place. Persistence
times can increase dramatically in dark (bur-
ied), cold (polar), sterile, or dry (desert) envi-
ronments. It is recognized that such data
should not be misused to inappropriately
torque a chemical into meeting the screening
guidance values. Application of the screening
9-3
-------
Addition of Chemicals
criteria also anticipates consideration of the
environmental medium into which the POP is
released, preferentially distributed (air, water,
soil, and/or sediment), and passes through in
its transboundary movement (i.e., before it can
reach cold environments such as the Arctic;
Klecka et al., 2000).
Persistence in water, soil, or sediment is neces-
sary for the chemical to be available for uptake
by organisms, as a means of physical accumula-
tion, and as a reservoir for, or receptor of, long-
range environmental transport. The mechanism
by which persistence leads to the buildup of
chemicals in the environment is demonstrated in
Figure 9-1. For this theoretical scenario, Figure
9-la plots the accumulation over time of two
hypothetical chemicals with half-lives of 1 and 12
months, in either soil, water or sediment. Two
modes of release to the environment are shown
for each chemical. The first models a single
release of one hypothetical unit of chemical at
the start of each year, and the second assumes a
continuous release totaling one unit per year.
The release of chemicals at the start of each
year, such as would occur with once-annual pesti-
cide application, leads to an immediate increase
of 1 unit, followed by decline over the remainder
of the year. Annual repetition leads to the saw-
tooth appearance. Continuous release over the
entire year, such as from an ongoing byproduct
emission, results in a roughly linear increase in
the environmental concentration until steady
state is reached. At steady state for both release
scenarios (after —5+ half-lives), the amount emit-
ted to the environment equals the amount de-
graded, the latter being a function of the total
accumulation in the environment.
Taken a step further, Figure 9-lb graphs the rela-
tionship between chemical half-life and the concen-
tration at steady state. In other words, based on
steady state having been reached for all chemi-
cals, the graph displays the resulting steady-state
level for each and every chemical half-life. This
figure demonstrates that there is no theoretical
cut-off value for persistence that separates a
problematic chemical from a nonproblematic
one. Indeed, the accumulated concentration (C)
in the environment at steady state is linearly
proportional to the half-life (T1/2), following the
equation C = RT1/2 / In 2, where R is the ap-
plication rate (Rodan et al., 1999). The
longer the half-life, the greater the amount of
physical accumulation that occurs. As can be
demonstrated by extending Figure 9-lb, a
chemical with a half-life of 10 years will build up
1 Unit/Year Release
0 12 24 36 48 60 72 84 96 108 120
Time - Months
Figure 9-la. Accumulation curves. Upper graph half-life
12 months, lower graph half-life 1 month. Repeated
annual application of one unit leads to the saw-tooth
appearance. Continuous application of one unit over the
year leads to the smooth curve.
Source: Rodan etal., 1999.
1 Unit/Year Release
Half-life-Months
Figure 9-lb. Accumulation curves. Central line represents
continuous release totaling one unit per year. Upper and
lower lines bound the oscillation from a single release of
one unit repeated annually.
Source: Rodan etal., 1999.
9-4
-------
Addition of Chemicals
in the environment over a half century of use to
a concentration 14 times the concentration that
would have resulted from a single, annual appli-
cation. This represents physical accumulation in
the environment and is distinct from bioaccumu-
lation (to be discussed shortly). Any physical
accumulation in the environment increases the
potential for exposure to, and bioaccumulation
in, living creatures.
Another approach to setting screening criteria for
POPs is to examine measured laboratory and
field data for substances already widely acknowl-
edged to be of concern, e.g., the "dirty dozen,"
compared with data on other substances that are
not considered POPs (Figure 9-2). These data
can then be compared with proposed criteria
guidance values, marked here in gray at a persis-
tence of 6 months and a bioaccumulation factor
of 5,000. All 12 priority POPs (marked in red)
or their POPs transformation products (aldrin
converts to dieldrin, heptachlor to heptachlor
epoxide) exceed degradation and
bioaccumulation screening criteria adopted under
the Stockholm Convention, usually by large mar-
gins. The extent to which these POPs exceed
the screening criteria is obscured by the trunca-
tion of soil half-lives (necessary for ease of pre-
sentation) and the logarithmic scaling of the
bioaccumulation axis. Similar findings are evi-
dent from graphs of overall environmental persis-
tence generated by multimedia fate models
(Rodan et al., 1999).
Bioaccumulation
Bioaccumulation is the buildup of a chemical in
organisms compared with their surrounding
physical environment. For POPs, bioaccumu-
7
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2,3,7,8-Tetrachlorodibenito-p-diosin
Benzofajpyrcnc (snail)
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PHexabromobiphenyl
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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
Soil Half-life in Months
Figure 9-2. Bioaccumulation v. half-life in soil. Gray shaded bars represent POPs screening criteria. The
bioaccumulation factor is normalized to 5% lipid; the persistence times are truncated at three years.
UNEP POPs are listed in red; additional LRTAP POPs in blue.
Source: Rodan etal., 1999.
9-5
-------
Addition of Chemicals
lation generally relates to water insolubility and
the propensity of these substances to accumulate
in lipid media—animal fat. An indirect measure
of this propensity to accumulate is the octanol-
water partition coefficient (Kow), which mea-
sures the ratio of the equilibrium concentration in
an organic medium (n-octanol) compared with an
adjoining water medium. The Stockholm Con-
vention screening criterion for bioaccumulation is
centered on a bioaccumulation/bioconcentration
value of greater than 5,000 in fish (Table 9-1),
supplemented by additional evidence of
bioaccumulation potential sufficient to justify its
consideration.
Figure 9-3 graphs the logarithm (base 10) of the
bioaccumulation values in fish for a number of
organic chemicals (the 12 POPs in red) com-
pared with their corresponding Iog10
octanol-water partition coefficients (log Kow;
data reported in Rodan et al., 1999). A log
scale is necessary for this graph because of the
extreme Kow and bioaccumulation values for the
POPs. A base 10 logarithm value of 5 equals
105, or 100,000; 106 = 1,000,000; and 1037 =
5,000 (which is the BAF/BCF screening value in
the Stockholm Convention). If Figure 9-3 had
been graphed on a linear scale with the BCF val-
ue of 1 set at 1 millimeter height, then the page
7
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» I nbutyltin hydroxide • Tetracmoropenzenc *.fail_oar!mn?
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*renmion *Nonyl phenol
* Pentachloronitrobenzene
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Log Octanol Water Partition Coefficient
Figure 9-3. Bioaccumulation in fish v. logu octanol-water partition coefficient (Kow). Bioaccumulation
factor is normalized to 5% lipid. UNEP POPs are graphed in red (square marker), additional LRTAP
POPs in blue (circle marker).
Source: Rodan etal., 1999.
9-6
-------
Addition of Chemicals
would need to be more than 3 kilometers (2
miles) long to fit the PCB bioaccumulation value
of >3,000,000.
In addition to confirming the extreme BAF/BCF
values for the POPs, Figure 9-3 also demon-
strates a number of technical issues pertinent to
bioaccumulation and which factor into the ap-
praisal of screening values:
:$ There is an approximately linear relation-
ship between the octanol-water partition
coefficient and bioaccumulation for the
majority of the organic chemicals (see Isnard
and Lambert, 1988), albeit not for the
organometals. This relationship provides a
mathematical link between the screening
values of logKow >5 and BCF/BAF >5,000.
;?; The slope of this graph increases after
logKow values of ~5, demonstrating
biomagnification in the food chain.
;?; The metabolism of some organic chemicals
in more phylogenetically developed species
can limit bioaccumulation, in this case dem-
onstrated by differences in benzo[a]pyrene
bioaccumulation between snails and fish.
:$ The majority of organic chemicals (bottom left
of graph) do not possess the extremes of
bioaccumulation exhibited by POPs.
Recall that the combination of data on two of the
four POPs screening values in Figure 9-2
(bioaccumulation and soil persistence) commences
a process of separating chemicals that may pose
transboundary or global problems from the major-
ity of organic chemicals. The inclusion of data on
the remaining two screening factors of toxicity and
long-range environmental transport further informs
this separation.
Fundamental to the need for a global POPs con-
vention is the transboundary nature of the prob-
lem, on a scale greater than can be resolved
through bilateral or even regional agreements.
With this understanding, the long-range environ-
mental transport criterion can be informed by
either (1) measured or monitored levels distant
from sources of release to the environment or (2)
modeling of a substance's environmental fate
properties, compared with known POPs sub-
stances.
Measured levels of potential concern in remote
locations distant from sources of release can
unambiguously satisfy the long-range transport
criterion. Indeed, the long-range transport prop-
erties of many of the "dirty dozen" were origi-
nally highlighted by their being found at signifi-
cant levels in remote locations, such as the Arctic
and mid-Pacific. It would be inappropriate,
however, to await elevated levels in remote loca-
tions before anticipatory action is taken: thus,
the additional criterion options of monitoring
levels in transport media and modeling based on
chemical properties.
For transport monitoring and modeling, it has
been demonstrated that the substance's persis-
tence in the transport medium (air or water)
strongly governs the distance traveled (Rodan et
al., 1999; Klecka et al., 2000). This analysis of
persistence in a transport medium differs from
the theoretical soil persistence analysis presented
above, because it incorporates a finite time
limitation, namely the time necessary for a sub-
stance to move from source to site of deposition.
The key question is how long a substance needs
to remain airborne or waterborne to constitute a
problem warranting international action. This
time period is directly related to the geographic
scale of interest. For a global negotiation, that
scale can be considered the transoceanic or
transcontinental distance. Assuming a scale of
ca. 4,000 kilometers (2,500 miles), it can be
shown that approximately 7 to 10 days would be
required for atmospheric transport from source
to site of deposition. This assumption is based
on average air movement rates across the
United States of 7 m/sec (Draxler et al., 1991)
and computer modeling of air movement on a
global scale (Mason and Bohlin, 1995). As dem-
onstrated in Figure 9-4, for a chemical with a 2-
day degradation half-life in air, the amount re-
maining after this approximate 8-day period is
9-7
-------
Addition of Chemicals
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0123456789 10 11 12
Days Since Release
Figure 9-4. Proportion of a POPs release remaining for
various atmospheric half-lives.
1/16 (2~4) of the original release. Lower atmo-
spheric half-lives lead to considerably smaller
residual amounts after 8 days, due to the shape
of the mathematical relationship between the
proportion of chemical remaining at time t
(m/m0) and the half-life (TI/Z) [m/m0 =
exp(-ln(2)t/T1/2)]. This is consistent with the use
of a 2-day half-life screening guidance for degra-
dation in air.
A similar analysis can be performed for water
transport, although it will be more complex be-
cause water movement rates are considerably
slower and much more variable. Figure 9-5 pro-
vides oceanic surface current estimates in the Pa-
cific and Atlantic Oceans based on drifter analysis
(www.aoml.noaa.gov/phod/dac/dacdata.html).
The scale for the arrows of 25 cm/sec is equivalent
to 0.9 km/hr or 0.56 mph. As discussed in Chap-
ter 7, rapid oceanic currents are evident for the
Gulf Stream (U.S. East Coast) and Kuroshio current
(east Asia). Average oceanic surface water speeds
are estimated at around 10 cm/sec (0.36 km/hr)
(Klecka et al, 2000). Certain oceanic currents can
rapidly move large masses of water long distances.
For instance, the Gulf Stream off the U.S. East
Coast has a speed of around 1 knot (1.7 km/hr)
off Cape Hatteras, up to 6 knots (10 km/hr) maxi-
mum, and transports as much as 100 million cubic
meters of water. Rivers generally move at
1-3 km/hr in nonflood situations.
To account for this variability in oceanic current
speeds, Figure 9-6 presents a modified version
of the theoretical analysis presented for air in
Figure 9-4. Figure 9-6 again sets the necessary
transport distance at 4,000 kilometers (2,500
miles), but this time plots oceanic current speed
on the x-axis versus the percentage remaining at
4,000 kilometers on the y-axis. Different half-
lives in water are represented by the different
lines (color-coded) on the graph. Examples of
representative oceanic current speeds are
marked on the table (from Klecka et al., 2000;
Leonard et al., 1997; Brown, 1991; Ross, 1978,
1982). Point X provides an example of how to
use Figure 9-6, representing a substance with a
AnouiJ MCM 1J-ID Velocity l->u V.-JCL
11[) IPO 13O 1 '5O TBO 170 Ktt) -"70 -lltfj '50 Vfl -13O 1?O *10 1QO -HO «) -70
Loncfctlfc UJtlFTEIi A*SniB!.T CEXTBft
Ir.dxbi Bin Malign tm*K >[»,-„ PlsM
Annual Mean 15-m Velocity Estimates
SO
70 -60 -50
s tteoisgS S/2000
DRErTBIt A£5EM£LT CENTER
Mlrn ?„„
Figure 9-5. Oceanic surface current speeds (NOAA).
9-t
-------
Addition of Chemicals
Release Remaining After 4,000 km Aquatic Transport
Aquatic lialflivcs of 1 - 6 months
100
o
o
o
01
=
U
a-
0.1
0.5 1
Water speed (km/hr)
10
Figure 9-6. Water transport model.
half-life in water of 2 months, caught in the Gulf
Stream. After 2,500 miles transport at ~1 knot,
30% of the original release would remain. Fur-
ther informing the evaluation of a pertinent half-
life criterion in water is the approximate 1/40
ratio for wind speed to oceanic surface current
(UK Ministry of Defense, 1973). These analyses
are consistent with the Stockholm Convention
half-life criterion in water of 2 months (under
Annex D, l(a)), but are clearly highly dependent
on which waterbody and current are under con-
sideration.
Beyond these first-order transport comparisons, a
number of multimedia environmental fate and
transport models have undergone recent develop-
ment (Klecka et al., 2000). It is anticipated that
these or similar models may be used to satisfy
the Stockholm Convention long-range environ-
mental transport modeling requirements. Multi-
media models are necessary because POPs dis-
tribute to, and move between, air, soil, water,
and sediment media. To adequately understand
the fate and transport of POPs in the environ-
ment, it is necessary to know how they will dis-
perse among these media, all of which exhibit
different degradation rates and abilities to act as
storage reservoirs or transport media.
An example of such a multimedia model related
to the 12 priority POPs is provided by Scheringer
et al. (2000), and replicated here in Figure 9-7.
In this graph, the x-axis represents total persis-
tence in the environment; the y-axis shows spa-
tial range normalized to the Earth's circumfer-
ence. Total persistence is the weighted average
of residence times in all the media, a method of
merging persistence values in different media
into a single figure. The spatial range is the
distance a chemical could theoretically travel in
the model before reaching a predetermined cut-
off level. From this graph, it is evident that
distance traveled is not linearly related to total
environmental persistence. This lack of linearity
is due to differences in the strengths of binding
to immobile particles in soil or sediment. This is
combined with the fundamental link between
transport distance and the half-life in the trans-
port medium, which sets a maximum possible
distance function irrespective of degradation
rates in soil or sediment. A similar modeling
analysis by Rodan et al. (1999) confirmed the
potential for the 12 priority POPs to travel long
distances. It is important to note that these
models only compare the relative distance trav-
eled by chemicals. This is because the termina-
tion decision used for model concentration and
9-9
-------
Addition of Chemicals
R
100 - •
95 - -
90 • -
70
60
50 -
40 •
3d -
20 -
tetn F-I42b F-ll
«*** •
F-12
dl-cU»
12f
clkisaiie t
10
1000
10000
T(days)
Figure 9-7. Spatial range R (normalized to the earth's
circumference) and persistence rof various chemicals
based on results of the global model proposed by
Scheringer (1996). 1: hexachlorobenzene,
2: hexachlorobiphenyl, 3: mirex, 4: endrin, 5: DDT,
6: toxaphene, 7: chlordane, 8: dieldrin, 9: TCDD,
10: aldrin, 11: heptachlor, 12: lindane. See Scheringer et
al. (2000) for a more detailed interpretation of this plot.
Source: With permission, Wiley-VCH, ACS.
distance is arbitrary yet consistent; i.e., when is
the environmental concentration low enough to
conclude that the chemical is gone and the dis-
tance calculation should cease?
Toxicity is perhaps the most difficult criterion to
quantify in the screening process because it
inherently encompasses considerations of dose,
the complexity of which is best dealt with at the
risk profile stage. Merely finding a chemical at
extremely small levels with modern laboratory
equipment cannot be considered a prim a facie
case for toxic risks. This caution must be bal-
anced against the technical limitations of toxicol-
ogy and ecotoxicology to detect and quantitate
subtle adverse effects and the need to not await
the demonstration of overt toxicity in remote
locations before action is taken—a precautionary
approach. Guidance on how to resolve this di-
lemma, and achieve a balance between provid-
ing information at the screening stage versus the
more detailed risk profile, is best found by ana-
lyzing the text of the Stockholm Convention
(Annex D.l.(e) & D.2):
Adverse effects:
D. 1.
(e)
(i) Evidence of adverse effects to human health
or to the environment that justifies
consideration of the chemical within the scope
of this Convention; or
(ii) Toxicity or ecotoxicity data that indicate
the potential for damage to human health or
to the environment.
2. The proposing Party shall provide a
statement of the reasons for concern including,
where possible, a comparison of toxicity or
ecotoxicity data with detected or predicted
levels of a chemical resulting or anticipated
from its long-range environmental transport....
Here, negotiators anticipated a hierarchy of
toxicity evidence, with priority to be given at the
screening stage to actual "evidence of adverse
effects," justifying consideration in this global
Convention. The adverse effects screening crite-
rion can also be fulfilled with "data that indicate
the potential for damage," again emphasizing
the need for data—not speculation—but not at
the expense of awaiting irreversible harm. The
criterion category is then followed by a statement
of concern (Annex D.2) at the screening stage, in
which the proponent Party is to include, where
possible, a comparison of data with detected or
predicted levels. These efforts to provide quanti-
tative information on adverse effects—measured
or predicted—are to be further elaborated upon
and evaluated by the POPRC in the risk profile
stage (below).
A wide variety of human health and ecotoxicity
data are anticipated under this criterion. For
human health, numerous national and interna-
tional expert scientific bodies assess data to
determine if a hazard exists to humans. Many of
these bodies develop standards considered pro-
tective of health. The EPA reference dose, for
example, is an estimate of a daily exposure to
9-70
-------
Addition of Chemicals
the human population (including sensitive sub-
groups) that is likely to be without an appreciable
risk of deleterious effects during a lifetime
(www.epa.gov/iris). The U.S. Agency for Toxic
Substances and Disease Registry (ATSDR) devel-
ops Minimal Risk Levels (MRLs) for many envi-
ronmental contaminants (www.atsdr.cdc.gov).
Internationally, the WHO and International
Agency for Research on Cancer (IARC) are cen-
tral to developing health standards. Reliance on
all of these standards should, however, be tem-
pered by an understanding of how they are de-
rived, the use of uncertainty factors and public
health protective assumptions that reduce nu-
merical values below the actual research data
findings, and details and differences in the spe-
cific wording of the standards (e.g., tolerable
versus minimal risk versus safe). Ultimately, an
expert appraisal, including analysis of the pri-
mary published literature, should be undertaken
to fully inform deliberations.
For ecotoxicity, a similar process of problem for-
mulation is undertaken to identify stressors and the
animals and plants at risk. Quantitative data for
chemical stressors can come in the form of dose
estimates related to toxic endpoints or as tissue
levels associated with adverse effects. Ideally,
laboratory studies of toxic doses will include the
tissue levels associated with these effects, but this is
not always the case. The complexity of ecotoxicity
data is accentuated by species differences, interac-
tion with the species' ambient environment, mul-
tiple simultaneous stressors, and difficulties in deter-
mining low levels of toxicity, especially in field
situations (Beyer et al., 1996). Expert judgment
is again essential in exercising appropriate cau-
tion in determining the potential for adverse
effects.
The risk profile is central to the ultimate deter-
mination of whether a substance is a POP war-
ranting action under the Stockholm Convention.
The emphasis on a detailed scientific review and
expert judgment is paramount in recommenda-
tions by scientific bodies (Klecka et al., 2000;
CEG, 1998). The complexity of the detailed risk
profile can appear, however, somewhat contrary
to a more straightforward application of numeri-
cal screening criteria, with its expeditious, yet
possibly inaccurate, clarity. With this in mind, it
merits emphasis that passing the screening
phase of the addition of chemicals process does
not necessarily imply that a chemical will be
listed as a POP. This determination can only be
made after a critical review and analysis of all
the pertinent data. As stated in Annex E of the
Stockholm Convention:
The purpose of the review is to evaluate
whether the chemical is likely, as a result of its
long-range environmental transport, to lead to
significant adverse human health and/or
environmental effects, such that global action
is warranted.
The information requirements for the risk profile
include elaboration and review of the Annex D
(screening criteria) information, supplemented by
Annex E information on sources, hazards, environ-
mental fate and models, measured levels, and na-
tional and international assessments and status.
The profile will be prepared by the POPRC, with
data input from Parties and observers (e.g., indus-
try, nongovernmental, and intergovernmental
organizations). It is recognized that more detailed
initial submission packages by proponent Parties
covering these points will expedite the process.
After a determination is made by the POPRC that
a substance is likely to be a chemical warranting
global action, information is then obtained on
Annex F management options and socioeco-
nomic considerations. A clear separation is
considered important between the risk profile
and management stages so that potential imple-
mentation considerations do not affect the scien-
tific evaluation of whether a substance warrants
consideration under the Stockholm Convention.
After such a determination is made, however,
Annex F explicitly requires consideration of tech-
nical and socioeconomic factors in determining
the best course(s) of action in dealing with a
chemical. To facilitate such decisions by the
9-77
-------
Addition of Chemicals
COP, the report on management options by the
POPRC will review the efficacy and efficiency of
possible control measures, alternative products
and processes, impacts on society of implement-
ing possible control measures, waste and disposal
implications, and additional factors influencing
the ability of Parties to implement obligations.
The ultimate decision to list a chemical in the
annexes and on appropriate control strategies
rests with the Conference of the Parties. This
decision must give due consideration to, but is
not bound by, the recommendations of the
POPRC in the risk profile and management
report. In doing so, the Stockholm Covention
seeks to maximize the input of scientific infor-
mation from multiple sources (intergovernmental,
government, industry, nongovernment organiza-
tions) into a transparent decision making pro-
cess. Consistent with standards maintained
during the negotiation of the Stockholm Conven-
tion, decisions by the COP are to be reached by
consensus. Absent such consensus, a 3/4 major-
ity vote is necessary to add a chemical. Changes
to the information requirements and criteria in
Annexes D (screening), E (risk profile), and F
(risk management/socioeconomics) can be made
only by consensus, to maintain a consistent stan-
dard for evaluating proposals to add chemicals.
During the May 2001 signing ceremony for the
POPs Convention in Stockholm, Sweden, agree-
ment was reached to commence work on defin-
ing the structure and process for the POPRC.
Proposal dossiers for the addition of chemicals
may be pursued on a national basis in anticipa-
tion of entry into force of the Convention and
commencement of POPRC review functions, but
chemicals cannot be added in the interim. The
particular approach used by the POPRC and
COP to review and consider the first chemicals
for addition following entry into force will yield
valuable information on how the process will be
implemented in the future.
Beyer WN, Heinz GH, Redmon-Norwood AW, eds.
1996. Environmental contaminants in wildlife: Interpret-
ing tissue concentrations. SETAC Special Publications
Series. Boca Raton, FL: CRC Press, Lewis Publishers.
Brown J. 1991. The final voyage of Rapaiti: A measure
of sea-surface drift velocity in relation to the surface
wind. Marine Pollut Bull 22(1):37-40.
CEG. 1998. Report of the first session of the Criteria
Expert Group for Persistent Organic Pollutants.
Bangkok, Thailand, 30 October 1998. UNEP/POPS/
INC/CEG/1/3. http://irptc.unep.ch/pops/CEG-l/
CEGl-3.htm.
Chemical Manufacturers Association (CMA). 1996. PTB
[persistent, toxic, bioaccumulative] Policy Implementation
Guidance. Product Risk Management Guidance for
PTBs. Arlington, VA: CMA. February 1996.
Draxler RR, Dietz R, Lagomarsino RK, Start G. 1991.
Atmos Environ 25A(12):2815-2836.
Canada TSMP. 1995. Toxic Substances Management
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499/2-1995E. June 1995.
Klecka G, Boethling B, Franklin J, Grady L, Graham D,
Howard PH, Kannan K, Larson RJ, Mackay D, Muir D,
van de Meent D, eds. 2000. Evaluation of Persistence
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Environment. Pensacola, FL: SETAC Press.
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Isnard P, Lambert S. 1988. Estimating bioconcentration
factors from octanol-water partition coefficient and
aqueous solubility. Chemosphere 17(l):21-34.
Leonard KS, McCubbin D, Brown J, Bonfield R, Brooks
T 1997. Distribution of Technetium-99 in UK coastal
waters. Marine Pollut Bull 34(8):628-636.
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Addition of Chemicals
Mason LR, BohlinJB. 1995. Optimization of an atmo-
spheric radionuclide monitoring network for verification
of the Comprehensive Test Ban Treaty: U.S. Advanced
Research Projects Agency/Pacific-Sierra Research Cor-
poration Arlington, VA: PSR Report 2585.
NAAEC. 1998. Process for Identifying Candidate Sub-
stances for Regional Action under the Sound Manage-
ment of Chemicals Initiative: Report to the North Ameri-
can Working Group on the Sound Management of
Chemicals by the Task Force on Criteria. Montreal,
Canada: Commission for Environmental Cooperation
under the North American Agreement on Environmental
Cooperation.
Rodan BD, Pennington DW, Eckley N, Boethling RS.
1999. Screening for persistent organic pollutants:
techniques to provide a scientific basis for POPs criteria
in international negotiations. Environ Sci Technol
33:3482-3488.
Ross DA. 1978. Opportunities and Uses of the Ocean.
New York: Springer-Verlag.
Ross DA. 1982. Introduction to Oceanography.
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Scheringer M. 1996. Persistence and spatial range
endpoints of an exposure-based assessment of organic
chemicals. Environ Sci Technol 30:1652-1659.
Scheringer M, Bennett DH, McKone TE, Hungerbuhler
K. 2000. Relationship between persistence and spatial
range of environmental chemicals. In: Lipnick RL,
Mackay D, Jansson B, Petreas M, eds. Persistent
Bioaccumulative Toxic Chemicals: Fate and Exposure.
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UNECE-LRTAP. 1998. United Nations Economic
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Persistent Organic Pollutants. 24 June, 1998; Aarhus,
Denmark. http://www.unece.orQ/env/lrtap/.
U.S. Environmental Protection Agency (U.S. EPA).
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9-13
-------
i igures showing transport pathways traversed by
air masses en route to 11 sites within the United
States are provided in this Appendix. The figures
and the calculations on which these figures are
based were produced by the Center for Air Pollu-
tion Impact and Trends Analysis (CAPITA) at Wash-
ington University in St. Louis, MO, and can be
found at http://capita.wustl.edu.
The figures are based on the calculation of several
thousand trajectories calculated backwards for 10
days at 2-hour intervals from each of the receptor
sites for the year 1999. The different color shad-
ing in the figures refers to the probability that
trajectories passed over a given area before arriving
at the receptor site. The boundaries of each
shaded region represent lines of constant prob-
ability. The areas shaded in red have the highest
probability of being traversed by trajectories,
whereas those shaded in light blue have lower
probability. To obtain a truly representative
picture of the average transport pathways, in the
same way that climatological statistics are ob-
tained, these calculations would need to be re-
peated for several years. Further details regard-
ing the calculations can be found in Husar and
Schichtel (2001).
A-1
-------
Appendix
l. Aleutian Islands, AK
l. Aleutian Islands, AK
#/km2
100
January
July
October
A-2
-------
Appendix
2. Point Barrow, AK
2. Point Barrow, AK
-
October
/
A-3
-------
Appendix
5. Seattle, WA
6. San Francisco, CA
A-4
-------
Appendix
9. San Diego, CA
10. Big Bend, TX
Jan-u
Aprdl
October
A-5
-------
Appendix
ll.N. Minnesota, MN
January
April
t •
July.
October
12. St. Louis, MO
January
April
October
A-6
-------
Appendix
13. Everglades, Fl
i25 -,. January
April
Jul*
October
14. Rochester, NY
April
July.
October
A-7
-------
Appendix
15. Burlington, VT
July,
October
Reference
Husar RBH, Schichtel B. 2001. Ozone and PM air
quality analyses in support of public needs: Visualization
of transboundary air pollutant transport to the US.
Final report of Cooperative research agreement
CX825834. Accessible through http://
capita, wustl. edu/capita/capitareports/POPs/
TransportclimatologyJP.ppt.
A-t
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