"THERE may be worse fates than extinction." If Woody Allen said that you would expect a punchline. When a scientist delivers the opinion, you anticipate bad news. Our Stolen Future delivers that news in its subtitle - Are We Threatening Our Fertility, Intelligence and Survival? The culprits here are synthetic chemicals that, have been derailing sexual development and reproduction in some animal populations for over 50 years.
"With our shared biology and, shared contamination," the authors warn, "there is little reason to expect that humans will have a separate fate." The book has caused a scientific controversy in the US by demonstrating that hormone disrupting chemicals may be affecting our neurological as well as our reproductive development, ultimately "changing who we become".
Since the second World War, tens of thousands of chemicals have penetrated every region on earth. More than 50 of those chemicals have been shown to act as hormone disruptors, interfering with estrogen and testosterone production, and thyroid metabolism - the most basic functions for a species health and replication. We know the heavyweights - the pesticide DDT, large chemical families such as the 209 compounds classified as PCBs, the 75 dioxins, and 135 furans - but research constantly uncovers more substances that jeopardise animal health and fertility.
"All the evidence was there, we just never had anyone to put it together," says Dianne Dumanoski, co author with Theo Colborn and John Peterson Myers of Our Stolen Future. Ms Dumanoski is a science correspondent for the Boston Globe, Theo Colborn is a senior scientist in zoology with the World Wildlife Fund and John Peterson Myers, a zoologist, is director of the W. Alton Jones Foundation, supporting protection of the global environment.
Funded by the W. Alton Jones Foundation, Dr Colborn assembled evidence that forms a disturbing picture of chemicals capable of scrambling hormonal messages in both animals and humans. A former sheep rancher and pharmacist, Colborn's initial research in 1987 was on pollution effects in the Great Lakes. Fish were developing grotesque tumours, but that was a familiar horror. "Cancer causing chemical" was by then a household term.
But something else was wrong. In highly polluted areas, female herring gulls were nesting together in an emergency response to the shortage of males interested in mating or capable of reproduction. Scientific reports had indicated that DDT, PCBs and other synthetic chemicals, could act like the female hormone estrogen and disrupt the sexual development of birds. The males did not strut or breed, some developed female reproductive organs. At the top of the Great Lakes food chain, the gulls were storing PCBs in their fat tissue at far greater concentrations than those found in the water.
"The hand me down poisons had one thing in common," Dr Colborn emphasises, "they all acted on the endocrine system and disrupted hormones."
THE HUMAN endocrine system - the body's communication network based on hormones and receptors - may be exquisitely sensitive and precise, but it can be fooled. For 30 years from 1938, DES, a synthetic estrogen, was given to an estimated five million pregnant women in the US to prevent miscarriages. The daughters of those women had higher rates of reproductive tract abnormalities and deterioration of immune cell function. Neurological consequences are still being investigated. Most significantly the DES experiment proved that the human body could mistake a man made chemical for a hormone.
"DES made an end run around the body's defences," explains Dianne Dumanoski, "and the test effects on animals were exactly the same as they turned out to be on humans. History shows us that in this area we ignore animal studies at our peril."
Dr Colborn collated wildlife evidence - sterile bald eagles, male alligators with tiny penises, hermaphrodite Beluga whales - and laboratory evidence of chemical disruption in rodent endocrine systems. The possibility of similar derailment of human functions was inescapable.
"I became very concerned for humans from what I saw in animals," Colborn recalls, "after all, the endocrine system is a basic design, that arose early in the evolution of vertebrates." To those who dismiss animal test results as misleading in human cancer research, Colborn responds that scientists understand the working of the endocrine system far better than they do cancer cells.
"Our obsession with cancer blinds us to other dangers," Dr Colborn asserts. The other dangers quickly surfaced. A Danish study by Dr Niels Skakkebaek involving 15,000 men from 20 countries found that average male sperm counts had dropped 45 per cent between 1940 and 1990. Subsequent Scottish, Belgian and French studies validated those findings and evidence in 1992 suggested that the damage had occurred in the womb. The debate over these figures continues.
"The estrogen link is total bunk," Stephen Safe, a professor of toxicology at Texas A & M University commented in January, arguing that levels of synthetic estrogen in the environment are consequential compared to those naturally occurring in fruits and vegetables. "But we have a long evolutionary history with plant estrogens," Dianne Dunanoski responds. "The body can break them I down whereas half of the synthetic estrogens are stored in our body fat. And there are no natural equivalents to androgen blockers." Androgen blockers are synthetic chemicals such as DDE, a breakdown of DDT, that interfere with the male hormone.
"I'm tired of hearing about semen," says Bernard Weiss, a behavioural toxicologist at the University of Rochester. "We need to know more about the neurological effects of chemicals - what dioxin does, for example, when its' binds to a receptor connected with brain development." Our Stolen Future examines that question along with others concerning breast cancer, prostate cancer, endometriosis and ectopic pregnancies.
CRITICS dismiss such inquiries as contrived. "It's hypothesis masked as fact," toxicology Professor Michael Gallo told the New York Times. "It's a political movement and it's based on lousy science." Molecular biologist Bruce Ames agreed.
William Moomaw, Professor of International environmental Policy at Tufts University is not dismissive. "This is not a conviction on all counts, but it is a very strong indictment of chemical proliferation" he remarks, "With a provocative hypothesis, the authors - none of them crackpots - raise a vital issue.
Questions outnumber answers. That is the authors' point. "The risks come from the gap between our technical prowess and our understanding of the systems supporting life," they conclude. Certain facts are clear. Some 100,000 synthetic chemicals are currently available worldwide. Each year 1,000 new substances are introduced, most without full testing or review. In 1991, the US exported more than four million pounds of banned pesticides.
"But this is not an apocalyptic message," insists Dr Colborn. "The integrity of our DNA is intact and I'm convinced that industry is going to come through with changes." Responding to the book's hypothesis, the National Academy of Sciences has established an expert panel to assess a threat already recognised as profound for the human future.