How dangerous are PCBs?

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If any corporation were to dump 1 million pounds of PCBs in a river today, there would be an outcry unmatched by that of any other environmental disaster.

Scientific research leads to the inescapable conclusion that PCBs are harmful and should not be allowed to remain in the Housatonic River and its floodplain.  At the direction of Congress, EPA conducted a study of health risks of PCBs to wildlife and to humans.  Their study included a thorough and comprehensive review of the existing scientific literature.  According to the review:

“There is clear evidence that PCBs cause cancer in animals.  EPA reviewed all of the available literature on the carcinogenicity of PCBs in animals as an important first step in the cancer reassessment.  An industry scientist commented that ‘all significant studies have been reviewed and are fairly represented in the document.’  The literature presents overwhelming evidence that PCBs cause cancer in animals.  An industry-sponsored peer-reviewed rat study characterized as the ‘gold standard study’ by one peer reviewer, demonstrated that every commercial PCB mixture tested caused cancer.  The new studies reviewed in the PCB reassessment allowed EPA to develop more accurate potency estimates than previously available for PCBs.  The reassessment provided EPA with sufficient information to develop a range of potency estimates for different PCB mixtures, based on the incidence of liver cancer and in consideration of the mobility of PCBs in the environment…. In addition to the animal studies, a number of epidemiological studies of workers exposed to PCBs have been performed.  Results of human studies raise concerns for the potential carcinogenicity of PCBs.  Studies of PCB workers found increases in rare liver cancers and malignant melanoma.  The presence of cancer in the same target organ (liver) following exposure to PCBs both in animals and in humans and the finding of liver cancers and malignant melanomas across multiple human studies adds weight to the conclusion that PCBs are probable human carcinogens… EPA’s peer reviewed cancer reassessment concluded that PCBs are probable human carcinogens.  EPA is not alone in its conclusions regarding PCBs.  The International Agency for Research on Cancer has declared PCBs to be probably carcinogenic to humans.  The National Toxicology Program has stated that it is reasonable to conclude that PCBs are carcinogenic in humans.  The National Institute for Occupational Safety and Health has determined that PCBs are a potential occupational carcinogen.”

Other agencies agreeing with EPA are the American Cancer Society, the World Health Organization, and the National Institutes of Environmental Health Sciences.  EPA’s study went on to document the non-cancer effects of PCBs, including immune effects, reproductive effects, neurologic effects, and endocrine effects.  According to the Agency for Toxic Substances and Disease Registry (ATSDR) “Health effects that have been associated with exposure to PCBs include acne-like skin conditions in adults and neurobehavioral and immunological changes in children. PCBs are known to cause cancer in animals.”  It is impossible to reconcile this overwhelming evidence with GE’s claim that PCBs are harmless along the Housatonic River.

So why does GE insist that PCBs in the river pose no threat?  According to GE, …”the scientific evidence demonstrates that the toxicity values that EPA uses to assess cancer risks and non-cancer effects, which are based on studies of laboratory animals, do not reflect such effects in humans, and that, based on the human studies, there is no credible evidence that PCBs have caused cancer in humans (even in highly exposed PCB workers) or have caused adverse non-cancer effects in humans at environmental levels.”  So flying in the face of worldwide scientific opinion, GE says that PCBs are not harmful.  Sound like the tobacco industry?

Part of GE’s reasoning is that laboratory-based, controlled studies are done on animals, which they argue are  more sensitive to PCBs than are humans. So do they therefore believe that those overly sensitive animals are in danger in the wild along the banks of the Housatonic River?  Of course not. Let’s not follow arguments to their logical conclusions. We are to believe that animals are sensitive to PCBs in the laboratory and insensitive to PCBs in the wild.

We tell our children to look both ways before crossing a street – not because it’s impossible to make it safely to the other side without looking, but because we know that the odds of making it safely to the other side improve when we adopt good-pedestrian practices.  Cancer research and the research related to many other diseases and disorders are similarly statistic-based.  Although a link can seldom be made between a given person’s cancer and a given contact with an environmental toxin, we know that our odds of living long and healthy lives increase when we adopt PCB-safe practices.  It is this statistical uncertainty that GE points to when they say that EPA is ignoring science in claiming a link between PCBs and cancer and non-cancer diseases and disorders.  EPA isn’t ignoring science, and neither are the host of other national and international agencies and organizations that list PCB as a probable carcinogen and point to its connection to reproductive, neurological, endocrine, and other types of health problems.  To their credit, EPA is stating its position in a way that is consistent with the guidelines of science.  Although crossing the street without first looking both ways cannot be said to inevitably lead to an accident, we do see a statistical correlation between poor pedestrian practices and bodily injury.


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