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n continuing its mission of protecting human health
and the environment, the US Environmental Protection Agency (EPA)
launched the Persistent, Bioaccumulative, and Toxic (PBT) Pollutants
Initiative in November 1998. The PBT Initiative is an integrated
approach for addressing widespread problems associated with toxic
chemicals that persist and bioaccumulate in the environment.
Pollutants
such as mercury, polychlorinated biphenyls (PCBs), and some pesticides
have persistent, bioaccumulative, and toxic characteristics and
pose significant health and environmental concerns. Challenges
in controlling pollutants with these characteristics result from
their ability to transfer rather easily to air, water, and land,
and to travel long distances. Once ingested by fish, birds, or
mammals, many of these substances bioaccumulate, leading to body
burdens far in excess of levels found in the environment.
With frequent
exposure over time, the amount present in organisms' tissues
can build up and cause toxic effects. In humans, effects include
nervous system abnormalities, reproductive and developmental
problems, cancer and genetic impacts. Young children and developing
fetuses are especially at high risk.
Over the years,
a substantial amount of work has been done by federal and state
regulatory agencies, industry, environmental and public health
groups, and the scientific community to reduce the risk associated
with these pollutants. However, the following examples illustrate
the current imperative to continue to take action. Studies have
been conducted worldwide to understand more fully the impacts
of PBTs on human health and the environment. We have chosen to
summarize some of these major findings in two large geographic
areas.
Most PBT pollutant
releases occur between the Arctic Circle and the Tropic of Cancer,
where the majority of industrialized nations are located. In
this area, known as the North Temperate Zone, the general population
has detectable levels of dioxin in their bodies as a result of
eating contaminated meat, fish, eggs, and dairy products. EPA's
draft dioxin reassessment (1994) estimated cancer risk to the
US population from this exposure to be in the 1:10,000 to 1:1,000
range. Dioxin exposure is approaching levels associated with
adverse non-cancer effects (NHANES). Also, about 25 percent of
children and nine percent of the general US population are exposed
to a level of methylmercury that exceeds the current EPA Reference
Dose. Those who rely on fish as a main source of food have even
higher PBT body burden levels. US tribes tell the EPA that contamination
of subsistence foods is their main concern.
In the Arctic
Zone, located north of the Arctic Circle and centered on the
North Pole, PBTs are present due to long-range transport from
industrialized nations and exposure of migrating species. PBT
levels are substantial in the Arctic Zone and PBTs persist longer
there because of the low temperatures. Levels of PBTs are expected
to rise in the Arctic due to increased local and southeast Asian
industrialization. Global distillation alone means decades more
of PBT pollutants entering this area (Bard 1999).
For many Arctic
tribes, PBT contamination of subsistence foods is linked to their
long term survival. PBT exposures are aggravated by the fact
that high-food-chain meats are their major source of protein.
Extensive recent Canadian research suggests Alaskan wildlife
has high PBT levels. If confirmed, most animal protein sources
are in question. Often, for many of these populations, there
is no alternative but to eat contaminated food. (Alaskan and
Arctic Fish and Wildlife database, 1998 AMAP)
Some marine
mammal and bird populations are experiencing disease, reproductive
problems, and population declines, probably in whole or in part
due to contamination from PBT pollutants. A review on harbor
porpoises indicates that levels of organochlorines, especially
PCBs, are high enough to cause concern about maintaining the
population (Aguilar and Bornell 1995). Free-ranging orca whales
along the Pacific Northwest coast have PCB levels four to five
times higher than highly-PCB-polluted St. Lawrence beluga whales,
who themselves have serious health problems. Canadian Arctic
whales are providing the first statistical inference that PBT
(specifically, PCB) levels in Arctic species relate to subtle
health effects. (Lockhart 1995, AMAP 1998). A 1998 study by the
International Whaling Commission determined levels of contamination
among some marine mammals are so high that the animals would
be classified as hazardous waste sites if they were on land.
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Like
other environmental departments around the world, the US Environmental
Protection Agency (EPA) has learned, little by little over time,
that the impacts of PBT contamination have not been, and could
not have been, entirely addressed by single-medium approaches
or by a singularly domestic approach. Addressing PBT contamination
requires a perspective that cuts across environmental media and
geographic boundaries. Therefore, EPA continues to stay the course
announced in its November 1998 draft PBT Strategy: that of taking
an increasingly holistic and integrated approach to addressing
PBT contamination.
EPA's PBT
effort will be accomplished by using all of the tools available
to the Agency - regulatory, compliance, enforcement, research,
voluntary actions, and international negotiations. The effort
also stresses an approach, but recognizes that, in some situations,
treatment and remediation will also be required.
EPA's commitment
to addressing PBT contamination implies a dual obligation: (1)
to account for the many significant areas of Agency activity
that are being integrated or need to be integrated, and (2) to
clarify how this process of increasing integration produces better
results. In numerous instances, EPA began integrating certain
PBT activities several years ago. The increasingly larger scale
on which this is being attempted presents a constant challenge
to the Agency.
Being the
first year of the Initiative, many of the activities in this
Report are new and/or ongoing and so have not produced formal,
quantifiable results. However, these planning, integration, and
development efforts have been included in order to recognize
their value to the Initiative in 1999 and beyond. Future editions
of the Report will undoubtedly have a greater emphasis on outcomes.
It is also important to note that this Report does not attempt
to capture each and every accomplishment made by the Agency and
its Regions with regard to PBT pollutants. Rather, it is our
hope that the following accomplishments demonstrate that the
PBT Initiative is making great strides in further integrating
the Agency's efforts a new way of doing business.
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