The Estrogen Complex
ALL LOUIS GUILLETTE WANTED TO do was to help figure out how many alligators could be hunted from Florida's Lake Apopka without making the population crash. But after years of wading (carefully) through the thigh-deep muck and sneaking up (warily) on alligator nests to snare the great reptiles with a noose, it dawned on him that the gators had bigger worries than winding up as pocketbooks. Male alligators' penises were only one quarter the normal size; their testosterone levels were so low they were probably sterile. Soon after, Guillette met a researcher who had seen similar effects on lab mice exposed to a cousin of the chemical DDE, formed when DDT decomposes. Not coincidentally, thousands of gallons of DDT-containing pesticide had spilled into Lake Apopka in 1980. Connecting the dots, Guillette said, "I think we have a problem here." By "we," he didn't mean alligators. Because people live in a sea of the same gender-bending chemicals, the University of Florida researcher recently told a congressional panel, "every man in this room is half the man his grandfather was."
It is a plot twist worthy of science fiction. Hundreds of the bedrock chemicals of the postwar age-PCBs used in the manufacture of electronics, pesticides such as endosulfan and atrazine, polycarbonate plastic found in many baby bottles and water jugs, chlorine compounds that bleach paper-resemble the human sex hormone estrogen. Although the compounds were concocted in the lab for purposes having nothing to do with human biology, their molecular structure turns out to be so similar to estrogen's that they fit into the same "receptors" in the body. (Contrary to popular belief, men as well as women produce estrogen, and so have receptors for the hormone.) The estrogen receptor can no more tell that it's being occupied by an impostor than a door lock can tell that a thief's skeleton key has been inserted. As a result, the estrogen mimics can trick the body into turning off, or ratcheting up, certain biochemical pathways especially those in the reproductive system. The result: sexual development, in both males and females, gone seriously askew. Since the impostors find their way into the soil, water and food supply, researching their effect on health "is a top priority for us," says Kenneth Olden, director of the National Institute of Environmental Health Sciences. "There's enough science out there to tell us we should be concerned."
For one thing, "half your grandfather" is no hyperbole. Since 1938, sperm counts of men in the United States and 20 other countries have plunged by an average of 50 percent, reported Danish endocrinologist Niels Skakkebaek in 1991. At the same time, testicular cancer has tripled. The trends could be a coincidence. But Skakkebaek suspects that the culprit in both the sparse sperm counts and the cancers may be men's exposure, as fetuses and newborns, to estrogenlike chemicals in their mothers' blood and milk.
While it's too soon to say that "background" levels of estrogenlike chemicals are responsible for the decline and fall of Western manhood, the case against high levels of the chemicals is clear-cut. In Michigan, estrogen mimics called PBBs accidentally got into cattle feed in 1973, and from there into beef Women who ate the meat, and whose breast milk harbored high levels of PBBS, had sons with testicular malformations and undersized penises. And in the closest thing to a controlled study in such a lucky field, Chinese scientists have been studying 118 boys in Taiwan who were born to women exposed to a PCB spill in 1979. Compared with boys whose mothers were not exposed, the 118 suffered reproductive defects like those of the boys in Michigan. These abnormalities "were probably related to hormonal changes caused by toxic exposure." the scientists conclude.
Now physicians are analyzing studies that link estrogenlike pollutants to breast cancer and endometriosis, the painful inflammation of the uterine lining that often causes infertility. Perhaps the oddest thing about endometriosis is that there were only 21 reported cases in the world 70 years ago; today there are 5 million in the United States alone. In a new German study, women with endometriosis were more likely than others to have high levels of PCBs in their blood. Some breast cancer may also have an environmental cause. Unusual amounts of DDE, the pesticide residue that seems to be leaving the alligators shortchanged, shows up in the tissue of women with breast cancer, according to a study last year by Mary Wolff of New York's Mount Sinai School of Medicine. Women with the greatest number of these DDE footprints were four times more likely to get breast cancer than women with the fewest such signs. The connection is plausible. This year the National Cancer Institute will begin a major study of the high rates of breast cancer on New Ye Is Long Island, assessing women's exposure to estrogenlike compounds in pesticides once used on the potato fields (and still in the aquifers) where suburbs now sprout.
Playing canary in the coal mine, wildlife "was the first to send signals that something was seriously wrong," says zoologist Theo Colborn of the World Wildlife Fund. Fish in places like the Great Lakes, where PCB and DDT concentrations are extremely high, and the terns and gulls that eat them, are becoming biochemical hermaphrodites: the males have reproductive parts of both sexes. Florida panthers, eating high on a food chain contaminated with estrogenlike pesticides, have their own reproductive problems: more infertile females, sterile males, lower sperm counts and high estrogen levels. One male, says toxicologist Charles Facemire of the U.S. Fish and Wildlife Service, "had estrogen levels higher than most females."
Despite such findings, "much of the evidence [about estrogen mimics] is circumstantial," says Thomas Goldsworthy of the Chemical Industry Institute of Toxicology. Although there is no question that the pollutants fit the body's estrogen receptors, there's still some wiggle room to argue that the chemicals do not switch on the same biological pathways that real estrogen does. Skeptics also ask w if the ubiquitous estrogen impostors really trigger cancers and other diseases, rates of the illnesses are not higher. Lawmakers may not wait for an answer. In February, the Clinton administration called for an 18-month study of chlorine (a component in many estrogenlike chemicals) to assess its effects on human health and the environment, with an eye toward restricting or banning it. A bill in Congress would phase out chlorine in the paper and pulp industries over five years. Hell has no fury like a congressman who discovers he's not the man he thought he was.
Alligators in a Florida lake have abnormally small penises and low testosterone levels.
Pollutants in body fat enter the blood and milk during pregnancy and lactation.
Hundreds of pollutants mimic estrogen's molecular shape. In males they may cause cancer and reproductive defects.
Men's sperm counts are down 50 percent since 1938, says one study.
Among the chemicals that mimic estrogen are widely used pesticides.