Isn't it just as possible that PCBs have a role in promoting carcinogenesis,
rather than being complete carcinogens themselves? We know that PCBs (and
certain congeners in particular) are very good at inducing the MFO system in
fish and laboratory mammals. Since chemicals such as benzo(a)pyrene require
enzymatic transformation to achieve their carcinogenic potential, it may
well be that the presence of PCBs in the environment potentiates these sorts
Ann Schnitz, Ph.D.
Gary Greenberg wrote in message <3A3716AF.E93EDA5B at Duke.edu>...
>American Council on Science and Health
>>http://www.acsh.org/press/editorials/pcb121200.html>>(Moderator Note: ACSH is an organization routinely dubious about new
>claims of environmental health dangers. Their editorials & press
>releases are presented to the OEM-L forum in an effort to provoke
>intellectual discussion, not as an endorsed point of view. For contrast,
>see the newsletters posted from RACHEL. -G)
>>Published in Wall Street JournalDecember 12, 2000
>>Who Says PCBs Cause Cancer?
>>by Elizabeth M. Whelan
>>Last week the Environmental Protection Agency proposed that General
>Electric spend $490 million dredging the Hudson River to remove what are
>known as polychlorinated biphenyls, or PCBs.
>>Until 1977, PCBs were used in the manufacture of transformers, adhesives
>and capacitators, among other things. GE legally dumped them into the
>river north of Albany for decades. The PCBs are now embedded in the mud
>beneath the Hudson, and are not generally dispersed in the water.
>>Media coverage has been murky as to exactly what the EPA hopes to
>accomplish with half a billion dollars of dredging. To clarify the
>agency's intent, I contacted EPA official Kevin Matthews. He explained
>that the EPA was worried about both the "health of the river" and about
>human health problems, particularly an increased risk of cancer from
>eating Hudson River fish.
>>But contrary to EPA assertions, there is no credible evidence that PCB
>exposure in the general environment, in fish, or even at very high
>levels in the workplace, has ever led to an increase in cancer risk.
>While reasonable people have suggested that dredging would displace
>buried PCBs and make matters worse, at this point we have no evidence
>that even high-level human exposure to PCBs causes any problem other
>than eye and skin irritation.
>>The EPA's assertion that PCBs in fish pose a human cancer risk is based
>solely on observations that high-dose, prolonged PCB exposure causes
>tumors in laboratory animals. But this is very different from the
>question at hand: Is there any evidence that the traces of PCBs in
>Hudson River fish increase the risk of cancer in humans? The EPA, an
>environmental regulatory agency, isn't known for its competency in the
>scientific discipline of cancer causation. We therefore need to turn
>elsewhere for expert opinions on any causal relationship between PCBs
>>An examination of the bible of cancer causation, "Cancer Epidemiology
>and Prevention" by David Schottenfeld and Joseph F. Fraumeni Jr.,
>reveals no reference whatsoever to PCB-containing fish (or any other
>source of PCBs) causing malignancy. This 1,500-page volume focuses on
>real human cancer risks, like tobacco use and overexposure to sunlight.
>But perhaps the ultimate authority on cancer risk is the National Cancer
>Institute. I put the question to the institute's director, Richard
>Klausner: Does NCI have any evidence that eating fish from the Hudson
>River contributes to the toll of human cancer?
>>This wasn't the first time I'd queried Dr. Klausner on cancer causation.
>Over two years ago the organization I head up, the American Council on
>Science and Health, composed (and had peer-reviewed) a similar, but
>broader, question for which we unanimously agreed the answer was no.
>(ACSH is an independent consortium of 350 physicians and scientists,
>funded by private foundations and corporations, including the GE fund,
>which accounts for about 1% of the group's total budget.)
>>Specifically, we asked Dr. Klausner: "At this time, does the NCI know of
>any credible scientific evidence that exposure to trace levels (parts
>per million or less) of synthetic chemicals in the general
>environmenteven if these chemicals have been shown in high dose to
>cause cancer in laboratory animals contributes to the toll of human
>cancer in the U.S.?"
>>As should now be obvious to GE and every other U.S. manufacturer, this
>is much more than a theoretical question. It has immediate, practical
>and costly implications. Congress, for example, has passed laws based on
>the premise that a "mouse is a little man." One, the "Delaney Clause,"
>states unequivocally that any synthetic food chemical that causes cancer
>in lab animals must be assumed to pose a human cancer riskno matter how
>minimal the human exposureand must be banned. Similarly, California's
>Proposition 65 requires that all consumer products containing even trace
>levels of animal carcinogens be banned or labeled. In short, decisions
>are being made, and limited resources are being committed, based on the
>assumption that trace exposures to animal carcinogens like PCBs pose a
>human cancer risk and must not be tolerated, no matter what the cost.
>>For over two years, NCI has refused to answer our original question.
>Presumably NCI has been resisting stating the obviousthat there is no
>evidence that trace levels of animal carcinogens pose a human cancer
>riskto avoid a head-on collision with the EPA, which for decades has
>been on a regulatory carcinogen witch hunt.
>>This week, however, the National Cancer Institute found its voice. Susan
>Sieber, a scientist and director of communications, told me that the
>institute knew of "no evidence" that eating fish from the Hudson River
>posed a human cancer risk. Why should we tolerate government policies
>that purport to prevent cancer by targeting environmental risks our
>nation's top cancer experts say don't exist?
>>Elizabeth M. Whelan is president of the American Council on Science and
>>If you wish to respond to this editorial please email your comments to
>forum at acsh.org, or visit the ACSH FORUMS at
>www.acsh.org/forum/chemicals/index.html to post them directly.
>>The American Council on Science and Health is a consortium of more than
>350 scientists and physicians dedicated to consumer education on public
>health issues, such as the environment, nutrition, and pharmaceuticals.
>ACSH attempts to illuminate the difference between real health risks and
>hypothetical or trivial health scares.
>Gary N. Greenberg, MD MPH Sysop / Moderator Occ-Env-Med-L MailList
>gary.greenberg at duke.edu Duke Occupat, Environ, Int & Fam Medicine
>OEM-L Maillist Website: http://occhealthnews.com>>>---