By Gerald and Natalie Sirkin
A front-page story on PCBs in the March 9 News-Times is just wrong.
The first thing to know about PCBs is that they never killed a single person nor did they ever cause cancer. The second is that although they are invariably called “cancer-causing,” that designation comes chiefly from a single rat study.
The third thing is that the subject rats were exposed daily for 21 months to 100 parts per million (ppm) of PCBs containing 60% chlorine. (The 100 ppm was about 5,000 times the tolerable daily intake of PCBs set by FDA in 1973.) When rats were exposed to PCBs containing less chlorine, they developed no cancers.
The fourth, that when the exposed rats were allowed to live out their lives, they had fewer cancers and lived longer than the unexposed rats.
PCBs is a family of chemicals known as polychlorinated biphenyls. PCBs contain chlorine ranging from 12% to 70%. They were used in two General Electric plants that manufactured electrical equipment.
Under the DEP, sampling has been done of fish in the Housatonic River since the early l980s to ascertain the PCBs in the River. The sampling is done at four sites, Cornwall , Bulls Bridge , Lake Lillinonah , and Lake Zoar , by a firm in Philadelphia . Where possible, samples of eight fish have been taken every two years at each site. The chief interest is trout and smallmouth bass. Smallmouth bass is the only species monitored at all four sites, according to the voluminous PCB Concentrations in Fishes from the Housatonic River, 1984—2004, and in Benthic Insects, 1978-2005, prepared for GE by the sampling firm.
The Report finds that with one exception, “None of the smallmouth bass samples in 2004” had PCB concentrations exceeding FDA’s standard. “Proportions of brown trout exceeding the FDA standard were lower in 1994-2004 than in 1984-1992. “
Though the concentration of PCBs has been declining, sampling continues under DEP’s overseer Ernie Pozzuto, successor to retired Charles Fredette.
In our anti-science era, politics trumps science. “But public panic, engendered by scare reports issued by public officials who have only the most superficial knowledge of the toxicology of PCBs and chloro DFs, is totally unnecessary,” according to California toxicologist Alice Ottoboni in her book, "The Dose Makes the Poison."
PCBs were banned by FDA in 1976. In 1984, FDA tightened its standard from 5 ppm to 2 ppm. The concentration of PCBs in the Housatonic meets that tougher standard. By 2004, the most recent sampling, the PCBs in the smallmouth bass were below 1.0 ppm at Bulls Bridge ; and brown trout were below 2 ppm. The goal of DEP appears to be lower still. Mr. Pozzuto does not contemplate ending the sampling in the foreseeable future, as he told us in a telephone call last week, though PCBs in the Housatonic has been steadily decreasing since 1992.
PCBs have never killed a single person. On the contrary, they have been life-saving. Elizabeth Whelan, president of the American Council on Science and Health (ACSH), remarks in her book, Toxic Terror, that “it is likely that PCBs saved lives in their functions of minimizing the risks of fires by replacing combustible insulating fluids.” Insurance companies sometimes required that PCB equipment replace the fluids.
It’s common for EPA to declare that a chemical is a suspected carcinogen. The Data Quality Act requires regulatory agencies to use the best available science. Often EPA doesn’t have the science, but that doesn’t stop it from declaring the chemical to be a “suspected carcinogen” (on the precautionary principle). It is a political, not a scientific decision, and is based on animal studies. ACSH has petitioned EPA to abide by the Data Quality Act, thus far to no avail.
The largest human study finding no link between PCB exposure and cancer mortality was done in 1999 by Dr. Renata Kimbrough of the Institute for Evaluating Health Risks. There were four earlier consistent studies at the National Institute for Occupational Safety and Health, Harvard School of Public Health, N.Y. State Department of Health, and Mt. Sinai School of Medicine. The data were GE employees in the two GE plants using PCBs. Kimbrough covered a longer period of time and 850 more employees (including 783 who had died). She looked for 28 different cancers among a total of 92 causes of death.
Kimbrough’s observations were 7,075 individuals who worked at least 90 days from 1946 to 1977. All were exposed through skin or inhalation to PCBs. She classified them by age, gender, hourly and salaried jobs, cumulative length of employment, latency periods to cancer. She compared her findings to the population in the region and the nation. None of those distinctions made any difference. Nor did blood-levels of PCBs, which ran as high as 2,530 parts per billion. (Nationally, they averaged 5 to 7 ppb). Comparing observed with expected causes of death, Kimbrough found that the observed in “All cancers” numbered 128, expected 158.
Declares The News-Times of PCBs, “They also work their way through the food chain—from bugs to fish, to waterfowl to humans.” But what does it matter if they are harmless? PCBs in food are of the lowest toxicity in Bruce Ames’s Hazard Ranking of Daily Human Exposure over a Lifetime. Examples: one hundred grams of cooked bacon present 30 times the risk of PCBs; one peanut-butter sandwich, 150 times; 12 ounces of beer, 14,000 times; a phenobarbital sleeping pill, 80,000 times. Ames is a world-renown microbiologist and cancer expert.
Concludes toxicologist Ottobani,
There is absolutely no evidence that PCBs contaminated with trace quantities of DF cause cancer in casually exposed humans. The best of this evidence is from epidemiologic studies of people whose jobs involved daily contact with PCBs. The absence of increased cancer rates in these groups makes it very difficult to believe that infrequent accidental exposures carry any cancer risk for the general public.
Tuesday, March 27, 2007
By Gerald and Natalie Sirkin