An Unscientific Fairy Tale
Our Stolen Future by Theo Colborn, Dianne Dumanoski, and John Peterson Myers (New York: Penguin Group, 1996).
Our Stolen Future is a book whose arrival was long awaited by activists in the environmental movement.
The book's coauthor and heroine, Theo Colborn, has been prominent in the campaign against chlorine led by Greenpeace and the Sierra Club. The book's most alarming claim -- that synthetic chemicals might be responsible for a steep decline in human fertility levels -- has been hyped by weekly new magazines and television's investigative news shows. Our Stolen Future promised to be, as Vice President Al Gore says in the book's foreword, the long-awaited sequel to Rachel Carson's Silent Spring.
Regrettably, this book falls well short of its advance billing. It will surely disappoint readers hungry for objective research and responsible advocacy on the complicated matter of synthetic chemicals in the environment. And it will go down in history's book catalog as just one more in a long line of books that frightened rather than informed the general public.
The authors of Our Stolen Future paint a dark and frightening landscape where animals are born with hideous deformities and die of mysterious wasting diseases; potentially dangerous chemicals are ubiquitous; and the sexual development of the human fetus is under constant assault by a toxic soup of hormone-mimicking synthetic chemicals that can deform sexual organs, reduce intelligence, and lead to aggressive and antisocial behavior.
Books such as Our Stolen Future necessarily raise the question of why the great majority of scientists and doctors have not reported this public health crisis, and when asked are generally skeptical of its existence. When Rachel Carson made similarly alarming claims some 34 years ago (her claims focused on a possible link between synthetic chemicals and cancer), she offered two explanations for the silence of her peers. Some, she wrote in Silent Spring, had "fallen into a mesmerized state that makes us accept as inevitable that which is inferior or detrimental." Others had been captured by "a fanatic zeal" to "create a chemically sterile, insect-free world."
The authors of Our Stolen Future use essentially the same reasoning, updated for the politically correct 1990s. They say doctors are blinded by an "anthropocentric tradition [that] reinforces the notion that humans are a unique branch on the tree of life." Scientists, they say, have focused too tightly on cancer and are now in the grip of "the inertia of institutions and ideas." These explanations seem, to this reviewer, to be as lame as Carson's three decades ago. They are unproven and unprovable assertions that, even if true, would be inferior to the task of casting doubt on an extensive scientific literature opposing the authors' theory and claims. More importantly, excuses such as these would not be necessary if the authors were genuinely working within the bounds of scientific proof.
Which leads us to the real problem with Our Stolen Future that it surely is not "within the bounds of scientific proof." The authors claim that the complexity of the relationship between synthetic chemicals and human health means "those who demand such definitive 'proof' before reaching a judgment are certain to be waiting an eternity" and "neat cause-and-effect links will remain elusive." Like other environmentalists, they say complexity legitimizes "judgment based on 'the weight of the evidence' rather than on scientific ideals of proof."
While there is nothing wrong in principle with the weight-of-evidence approach, it is not an excuse for selectively reporting research or for relying on outdated or methodologically compromised research. Yet, this is precisely how the authors of Our Stolen Future go about building their case against synthetic chemicals.
For example, the authors rely heavily on an epidemiologic study by Sandra and Joseph Jacobson et al. (page 24, 190-193, 214) This study alleged to have found an association between toxic chemicals in the Great Lakes and low birth weights and developmental deficits among infants born in 1980 and 1981. The small sample size (fewer than 200 mothers of newborns) and the manner in which subjects were selected, however, severely compromise the study. Other methodological problems include:
Recall bias: Subjects were asked to recall how many fish meals and what kinds of fish they consumed during the six years preceding their pregnancies. These recollections formed the most important data in the study, yet they are likely to have been very inaccurate. For example, a meal of lake trout was assumed to contain five times the does of toxic chemicals as did a meal of brook trout. Can you accurately recall how many meals of fish you've had during the past six years, and how many of them were lake trout as opposed to brook trout?
Confounding factors: Mothers who recalled eating the most fish also tended to weigh less before pregnancy, were three times as likely to use alcohol during pregnancy, and were more likely to use cold medicines and consume caffeine during pregnancy. The number of twins born to women selected for the study was three times the number that would be expected to appear in a random sample. All of these factors are known to be associated with low birth weights and development deficits among newborns.
A weak association: Even if the study's results were reliable, they show only a very weak relationship between an infant's health and a mother's recollection of having eaten fish during the preceding six years. The results show no statistically significant relationship at all between an infant's health and the umbilical cord blood levels of PCBs. This measurement is considered to be the most accurate indicator of a fetus' in utero exposure to PCBs and, presumably, to other toxic chemicals.
Results not replicated: Subsequent epidemiologic surveys done in Wisconsin and North Carolina failed to confirm the associations thought to have been found by the Jacobson researchers.
The authors of Our Stolen Future must have been familiar with these criticisms of the Jacobson study when they wrote their book, yet no mention is made of the study's shortcomings.
The Jacobson study is typical of the caliber of research that appears in Our Stolen Future. The book's most highly publicized claim is that "human male sperm counts have plummeted over the past half century." (page 172) They later refer to this as a "truly alarming" trend (page 232). But closer examination of the data by scientists and doctors at the University of Washington, Columbia Presbyterian Hospital in New York, the Genetics and IVF Institute in Fairfax, Virginia, and Baylor College of Medicine disputes this claim and even reveals a small increase in sperm counts since 1970.
Louis Sullivan, former secretary of health and human services, observes that the most explosive growth in world population is occurring in those underdeveloped countries where exposure to suspect chemicals is the greatest. He correctly calls this "real world verification" of studies showing that global human fertility rates have not been compromised.
Their quest for a "weight of evidence" case even leads the authors to rely on admitted hearsay at odds with current scientific knowledge: on human carcinogens in Great Lakes water (pages 12, 15); on dioxin as "the most toxic chemical on earth" (page 113); on the effects of Agent Orange (page 114); on the supposed rising rate of prostate cancer (page 180); and on "a breast cancer epidemic" (page 182).
In most cases, these references to hearsay are followed by vague references to scientific research that reaches different conclusions. But this only begs the question of why the hearsay is cited in the first place. It seems fair to conclude that the authors believe even hearsay is allowable when building a weight-of-evidence case.
A final example of discredited research is the discussion of alligators with small penises in Florida's Lake Apopka (pages 150 - 153). The authors try to pin the blame on high levels of DDE (a DDT metabolite) and a 1980 spill of the pesticide dicofol. But this explanation ignores the heavy loads of other pollutants that were so toxic they were causing fish kills and the death of alligators, turtles, and other wildlife dating back to the 1950s. Wildlife in the lake was exposed to extraordinary levels of myriad toxic substances for a period of several decades.
What lessons could such an experience possibly hold for humans not exposed to, or exposed to only minute levels of, these compounds?
J. Gordon Edwards, a biologist and professor emeritus at San Jose State University in California, has documented the history of Lake Apopka. He points out that current levels of DDE in the lake are no higher than in lakes where no reproductive disorders among alligators and other forms of wildlife are reported. Why stretch for an explanation when more obvious ones are readily at hand?
The reason, of course, is that DDT was Rachel Carson's favorite target. Three decades after "Silent Spring," the environmental movement is still trying to make the case against this long-since banned pesticide. Amazingly, it still is coming up short.
Our Stolen Future calls DDT "a classic estrogen mimic" (page 86) and claims it plays a major role in breast cancer (pages 184-185, 200-202). But the authors ignore the latest and largest studies, published by the National Cancer Institute in 1994, showing no relationship between DDT (or for that matter PCB serum levels) and breast cancer risk and attributing rising breast cancer rates to better detection and diagnosis.
Readers of Our Stolen Future should take offense at the abuse of sound science performed under the guise of assembling a "weight of evidence" case against synthetic chemicals. The authors repeatedly insult the reader's intelligence by withholding evidence, claiming evidence exists when it does not, and making sweeping (and alarming) generalizations when none is justified.
For all of this, Our Stolen Future is still an important book, but not because it focuses attention on a public health emergency. Rather, its importance derives from the fact that its authors are still unable to meet the standards of scientific proof that eluded Rachel Carson three decades earlier. This book stands as testimony to the nearly complete lack of progress that has been made by environmentalists during the past three decades to make their case against synthetic chemicals.
The intellectual impotence of Our Stolen Future may be good for the environmental movement. By signaling the end of the journey into chemophobia begun 34 years ago by Rachel Carson, the book may free environmentalists to finally pursue other routes to environmental protection. The new environmentalism that emerges may be unrecognizable to Carson, or even to the authors of Our Stolen Future. But we can be sure the environment and human health would benefit by its conception.
Joseph Bast is president of The Heartland Institute, a nonprofit research institute based in Palatine, Illinois. He is also coauthor of Eco-Sanity: A Common-Sense Guide to Environmentalism, which was recently released in paperback by Madison Books.