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FE NEWS SERVICE
US environmental scientists, disputing the claims of an industry-funded study that synthetic substances known as ``PCBs'' were not a cause of cancer, declared recently that the chemicals posed a significant threat to human health and wildlife. The study, published in a recent edition of the Journal of Occupational and Environmental Medicine, found there was no significant link to cancer among workers exposed to polychlorinated biphenyls or PCBs.
The hotly-contested research was funded by the General Electric Corporation (GE), which curently faces multi-million dollar civil suits over the health effects caused by the US-based company's past dumping of mass amounts of PCBs into rivers in the state of New Yrok.
Scientific experts, including several from the US Environmental Protection Agency (EPA), said the GE study wrongly focussed on deaths caused by cancer instead of examining the children of the workers exposed to the chemicals.Researchers should have tested the children of these workers for possibleimpacts, they said.
Also, the study should have considered the mouting documentation that children whose mothers were exposed to PCBs during pregnancy had significant immune systenm problems, neurological amd motor delays, and learning and reproductive problems, the scientists added.
``The GE study did not ask the right questions,'' said Theo Colborn, a senior scientist with the World Wildlife Fund in Washington.
``GE is using cancer as a red herring to ignore the evidence that children exposed to PCBs in the womb have significant neurological problems and negative impacts on their intellignece and behaviour, and audio visual comprehension problems,'' she said. PCBs-used worldwide as insulators in transformers and other electrical equipment and in the production of plastics-are among a dozen substances targeted by an international treaty to eliminate Persistent Organic Polluants (POPs).
PCBs, like other POP chemicals including DDT and dioxins, also ``bio-accumulate''. When consumed, they are notexcreted but build up in fatty tissue. Therefore many animals, including those high up in the food chain, retain heavy doses of the chemicals. They are called ``persistent'' because of their longevity and because of their ability to travel long distance by wind and water. PCBs and other POPs have been found as far as the polar ice caps and in the body fat of the Inuit indigenous people living on Baffin Island in the Canadian Arctic.
In 1995, in order to address these health and environmental threats, about 100 countries agreed to negotiate a global treaty to eliminate POPs early in the next century. Formal negotiations are expected to be completed by the year 2000. The production of PCBs in the United States was banned in 1977. The EPA later classified the substances as ``probable human carcinogens'' and still ranks them in the ``top 10 per cent of the most toxic chemicals to human health.'' These chemicals, however, were still being used in older equipment and continued to enter the environment throughpoorly maintained toxic waste sites and the illegal dumping or disposal of PCB-containing products such as older refrigerators, according to environmental scientists.
The GE study focussed on more than 7,000 men and women who worked from 1946 to 1976 in two GE factories in in upstate New York. It followed their medical histories for an average of 31 years and compared the causes of death of the 1,195 who have died to national and regional averages. It found that 353 GE workers died of cancer, while 400 people would be expected to die of cancer in a statistically similar sample. ``The findings of this study are consistent with a belief that cancer risks from exposure to PCBs have been overstated,'' said John A More, president of the Institute for Evaluating Health Risks.
Such statements bolstered GE's crusade to convince the public that PCBs pose no risk to public health and safety. The company has spent more than $ 100,000 in advertising to convince residents living near sites where PCBs were dumped thatthey should not be concerned about the chemicals. ``There is no direct scientific evidence that PCBs cause cancer in humans,'' GE said in one advertisement, that did not deny the dumping.
Linda Birnbaum, director of the experimental toxicology division of the EPA, declared that the GE study was seriously flawed. ``They lumped workers together-who worked with different mixtures of PCBs-and we know that different PCB mixtrures have different effects,'' she said.
The workers studied in the research had only limited exposure to the most toxic or carcinogenic PCBs, said Birnbaum. ``I think this is a clear example of what you don't look for, you won't find.''
She pointed to many other studies that have shown an association between PCB exposure and cncer. ``One negative study does not negate all the positive ones,'' said Birnbaum. ``The US EPA, the National Toxicology Program and the International Agency for Research on Cancer all consider PCBs to be a probable human carcinogen.''
Even if PCBs could not belinked to cancer, the other health effoects caused by the chemcials were more significant, she said.
PCBs are known to be an endocrine disruptor -- which meant they blokced, mimicked or otherwise interfered with natural hormone system development and function. A recent study conducted by EPA research biologist Earl Gray found that a specific PCB caused diverse reproductive malformations in male rats, including deformed genitals, when they were exposed in the womb.
Other studies found that high levels of PCBs in umbilical cord blood were linked to low scores on neurological tests. And when the children were tested at age four those whose mothers had the highest levels of PCBs had lower scores on verbal and memory tests.
Similar impacts were found on the children in Japan and Taiwan who were exposed in the womb to PCBs and liquid from contaminated rice. They had developmental and reproductive problems, as well as immune system disorders. ``These kinds of characteristics which include learning difficultiesin children usually then lead to not being able to reach their full potential when they reach adulthood,'' said Colborn, who co-wrote the book Our Stolen Future, about endocrine disruptors. ``It would fascinating to find out where children who have been exposed to PCBs in the womb have ended up within their communities,'' she said. ``There are many different studies that could be done on this issue and GE is not doing them.
Copyright © 1999 Indian Express Newspapers (Bombay) Ltd.
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This story was printed from Net Express located at http://www.expressindia.com. Net Express provides a portal to India, with news from The Indian Express and The Financial Express along with sites on travel and tourism, the entertainment industry, the power sector, the environment and much more.
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