A Scary Warning Or Scare Story?John Carey
OUR STOLEN FUTURE
Are We Threatening Our Fertility, Intelligence, and
Survival?----A Scientific Detective Story
By Theo Colborn, Dianne Dumanoski, and John Peterson Myers Dutton
-- 306pp -- $24.95
What do the breakdown of the family, dead whales, shrunken alligator penises, hyperactive children, disappearing frogs, and breast cancer have in common? According to Our Stolen Future, a disturbing new book by Boston Globe writer Dianne Dumanoski and scientists Theo Colborn and John Peterson Myers, they all may be linked to the modern era's witches' brew of pesticides, plastics, and other man-made substances.
Many of these chemicals are capable of mimicking estrogen and other natural hormones. As a result, the authors argue, the substances may be wreaking havoc on the biological world. "We have become unwitting guinea pigs in our own vast experiment," they write. In addition to threatening people's ability to reproduce, the book warns, "chemicals that disrupt hormone messages have the power to rob us of...the essence of our humanity."
Unfortunately, such sweeping claims and overwrought prose go a long way toward robbing the book of its credibility. Nor does it help that the authors offer decidedly slanted interpretations of the data on such crucial issues as human sperm counts. The net effect is to push the book down the slippery slope from journalism to polemic--making it easier for the chemical industry to attack the entire argument.
That's a shame, because there is reason to be concerned about the hormone-like effects of chemicals, particularly on wildlife. "No scientist who has read this evidence can shrug it off," says Pierre Beland, senior scientist at the St. Lawrence National Institute of Ecotoxicology in Montreal, in reaction to the book. Consider the failure of ranched mink to bear young after being fed PCB-laden fish from the Great Lakes in the 1960s. Or look at the alligators of Florida's Lake Apopka. In the years following a 1980 pesticide spill, most eggs failed to hatch--and males that did survive had abnormally small penises.
The list of species in which researchers have found behavioral or reproductive changes consistent with exposure to estrogen-mimicking chemicals includes eagles, beluga whales, otters, and gulls. Moreover, lab studies show that small amounts of these chemicals given at crucial times during embryo development can have a wide range of effects, such as making rats less able to handle stress. The new evidence adds weight to the already overwhelming arguments for continuing the battle against pollution.
But is this "hormone havoc" plaguing people, too? For the authors, the answer is "inescapable: the hormone disrupters threatening the survival of animal populations are also jeopardizing the human future." And "the most dramatic and troubling sign" of this is a plunge in human sperm counts over the past 50 years. The main evidence: a 1992 Danish report that combined dozens of previous studies to claim a 50% drop.
Trouble is, the report is seriously flawed. Indeed, a more sophisticated 1995 reanalysis of the same data and several soon-to-be-published studies by researchers at the University of Washington and Columbia Presbyterian Medical Center show no sperm-count change at all over the past 25 years. "There's no convincing evidence of a global problem," concludes urologist Larry I. Lipshultz of the Baylor College of Medicine in Houston. Without such evidence, much of the argument for a human threat collapses.
Our Stolen Future also stumbles on the crucial question of whether synthetic hormone-mimics are intrinsically different--and more dangerous--from myriad similar substances found in nature. The book does note that a wide variety of plants--from garlic to wheat--harbor chemicals that also act like mammalian hormones. And some researchers estimate that people are exposed to thousands or even millions of times more of these natural chemicals than the man-made substances.
The book argues, however, that the synthetic chemicals have a far greater effect than natural ones because they linger longer in the body and there hasn't been time for evolution to allow the body to adjust to them. Many environmentalists have used these same arguments to claim that, as causes of cancer, pesticides and other synthetic chemicals are much more worrisome than the far larger amounts of natural carcinogens people eat every day. Indeed, many activists have issued dire warnings about soaring cancer rates caused by man-made chemicals.
But the claim hasn't held up. In fact, after Colborn spent months poring over cancer data, the book tells us, she came to the conclusion that "the high cancer rates she had heard so much about appeared to be more myth than reality."
This startling admission from the environmentalist camp doesn't prove, of course, that synthetic chemicals aren't more potent as hormone disrupters than natural substances. But it does show that on this key question of proving that man-made factors are more significant than natural ones, the environmentalist track record is not good. Moreover, the fact that people are living longer seems to challenge the notion that we're doing awful things to ourselves with chemicals.
This doesn't mean that countries and companies shouldn't try hard to reduce the amounts of chemicals they spew into the world, as the authors recommend. But with its selective use of data, dubious logic, and relentless hype, Our Stolen Future ends up doing a serious disservice to its own cause.