SOME CHEMICALS ARE MORE HARMFUL THAN ANYONE EVER SUSPECTED
By Peter Montague
New evidence is flooding in to suggest that many industrial chemicals are more dangerous than previously understood. During the 1990s, it came as a surprise that many industrial chemicals can interfere with the hormone systems of many species, including humans. Hormones are chemicals that circulate in the blood stream at very low levels (parts per billion, and in some cases parts per trillion), acting like switches, turning on and off bodily processes. From the moment of conception throughout the remainder of life, our growth, development and even many kinds of behavior are controlled by hormones.
Now new evidence is piling up to show that some of these hormone-related changes can be passed from one generation to the next by a mechanism that remains poorly understood, called epigenetics.
Until very recently scientists had thought that inherited traits always involved genetic mutations -- physical changes in the sequence of nucleotides that make up the DNA molecule itself. Now they know that there is a "second genetic code" that somehow influences the way genes operate, and that by some poorly-understood mechanism can be passed along to successive generations.
Just last month professor Michael Skinner at Washington State University in Spokane announced results of laboratory experiments showing that environmental pollution could permanently reprogram the genetic traits of a family line of rodents, creating a legacy of sickness. This research "highlights the long-term dangers from environmental pollution," professor Skinner said. Dr. Skinner showed that a single exposure to a toxic chemical in the womb could produce a sick litter of offspring, which in turn could produce its own sick offspring. "It's a new way to think about disease," Dr. Skinner said.
"A human analogy would be if your grandmother was exposed to an environmental toxicant during mid-gestation, you may develop a disease state even though you never had direct exposure, and you may pass it on to your great-grandchildren," Skinner said.
"It introduces the concept of responsibility into genetics," says Dr. Szyf. As a recent story in the Toronto Globe & Mail summarized, "Epigenetics may revolutionize medicine, said Dr. Szyf, and it also could change the way we think about daily decisions like whether or not to order fries with a meal, or to go for a walk or to stay in front of the television. You aren't eating and exercising for yourself, but for your lineage."
Brominated flame retardants, phthalates, bisphenol-A, PFOA (related to the manufacture of Teflon) are the toxins that have gained our attention at the moment. By working overtime for 10 or 15 years in the traditional environmentalist way, we may be able to ban a half-dozen of them. But during that 10 or 15 years, the chemical industry (and the federal EPA) will have introduced somewhere between 7,000 and 10,000 new chemicals into commerce, almost entirely untested. This destructive merry-go-round is accelerating.
Faced with evidence of harm, governments tend to respond initially by conducting "risk assessments" to show there is no problem. The main function of risk assessment is to make chemical problems disappear, almost like magic. As EPA's first administrator, William Ruckelshaus, reminded us, "We should remember that risk assessment data can be like the captured spy: If you torture it long enough, it will tell you anything you want to know."