Our Pollutants could be changing our sex


 Environmental Hormones in the News

News stories on environmental threats from hormone mimics abound these days. Many focus on the potential breast-cancer risks posed by a woman's exposure to pollutants that function like estrogen.

Then there are the reproductive scares. In certain wildlife populations, females appear to have lost the ability to successfully reproduce. In others, male animals have been born with feminized reproductive organs. There are even provocative, though spotty, human data suggesting that males may be suffering from unusual rates of genital malformations and testicular cancer, and from unusually low rates of sperm production.

Perhaps most troubling, the proportion of male births appears to be waning in many industrial countries. The source of the pollutants suspected of triggering at least some of these dire effects include common pesticides, plasticizers, fuel additives, and surfactants. Not only do trace quantities of them lace our air and drinking water, but some have been detected leaching into our foods--from plastic lined cans, from plastic coated papers, and from plastic bottles.

Many animals, including various types of prized game fish, including lake trout and salmon, build up significant stores of these compounds in their edible flesh. Some of these chemicals even appear to leach directly into saliva from teeth treated with popular dental sealants.

Though the story of hormone-mimicking pollutants has been brewing for decades, even as recently as 5 years ago, only a handful of reporters had begun looking into it. The vast majority of their brethren wouldn't follow suit for another 3 years--until the publication of "Our Stolen Future," a book by zoologist Theo Colborn, biologist John Peterson Myers, and then-Boston Globe reporter Dianne Dumanoski. Since 1994, Colborn has been on a soapbox arguing that a series of disturbing and related trends suggest an environmental pandemic may be in the making--some subtle and malign reproductive impairment throughout the length and breadth of Earth's animal kingdom.

Initially, she ascended that soapbox only in the supportive company of fellow biologists. Gradually, Colborn became more outspoken about her fears, catching the attention of Congress, U.S. regulatory agencies, and captains of industry. Then, with "Our Stolen Future"--and the news blitz it evoked throughout respected major media leaders--she and her co-authors carried her chilling concerns to the general public, much as Paul Brodeur's" Zapping of America" brought the formerly arcane subject of electromagnetic fields to public attention.

Our "Stolen Future" offered solid background on the secret life of our bodies' endocrine system--and made for surprisingly good drama. Anecdotes and personality profiles humanized the science of our environment's hormonal threats to wildlife and its stewards. But even when the book debuted in March 1996, most of the events it portrayed were quite dated. Moreover, much of the research that it described may ultimately prove misleading. Indeed, that's the nature of science.

Even today, research on endocrine disrupter's remains in its infancy. As a result, the trends portrayed by news articles must necessarily be sketched from a remarkably small number of data points. Such a paucity of data leaves reporters or book authors free to extrapolate broadly on what the few, early findings suggest. As a field develops, however, it traditionally constrains the boundaries of what is real--or realistic.

So where today we are questioning to what extent estrogen-mimicking pollutants may reduce sperm counts in men, we might one day learn that only three of the dozens of "man-made" estrogens to which we are exposed employ a mechanism that can affect human sperm production. Or we might find out that any of these agents can affect sperm, but only if a man's mother had been exposed to them on day 17 of her pregnancy. Or only if the fatally exposed man smoked during his teen years. Or faced exposure to these "hormones" through the skin. Or... You get the point; the probability of any serious risks may be highly circumscribed. Which is why it's exciting to write about these issues today--while they're still so deliciously appalling, and nobody has proven that even the most outlandish prospects are categorically impossible.

A few individuals have begun suggesting that they might be, however. Gina Kolata in a March 1996 New York Times piece, for instance, quoted scientists who argued that concerns about hormone mimics must be considered premature until follow-up data demonstrate not only how pervasive and potent such agents are, but sciJanalso whether the initial studies were conducted appropriately. About the same time, a related story in the Washington Post by Rick Weiss and Gary Lee picked up the skepticism, noting that science "is better at scaring people than reassuring them."

Indeed, they charged that the mix of science, politics and public relations associated with Colburn's public campaign to put the issue of "endocrine disrupter's" firmly in the public eye "smells undeniably of spin but is nevertheless difficult to ignore." Anxious to contribute to that spin have been several chemical industry groups that have begun funding a few scientists to challenge the concerns that Colborn champions. To date these critics have largely pointed to those gaps in the data supporting the frightening trends and to a host of potentially countervailing effects of chemicals in the environment--ones that might ultimately block hormone action.

The Competitive Enterprise Institute, based in Washington D.C., took up the latter crusade in a report it issued at a press conference two days before the release of Colborn's book. It noted that Mother Nature has imbued some 173 plants (at last count) with hormone mimicking constituents--many of which we have been eating without harm for millennial. As such, it argued, because the hormonal alter ego of many pesticides and other synthetic chemicals is nothing new or unusual, Colborn's campaign to even infer otherwise represents "scare tactics" that "hit below the belt." Data gaps, and the hazards of offering speculations to bridge them, plague every fledgling field of science. But the initial trends that sparse data suggest can be bolstered or responsibly discredited only by additional research.