In one camp are supporters of the arguments outlined in Our Stolen Future , a popular 1996 book that linked these hormone-like contaminants to sexual mutations and declining sperm counts in animals. Sperm count and breast cancer studies continue to come up with seemingly conflicting results. Yet in December, a study was published in the Lancet that found high breast cancer rates among women with high blood levels of dieldrin, another banned pesticide. There is no quarrel about dioxin being a carcinogen, and Hauser says dioxin does, indeed, also have demonstrated anti-estrogenic properties. But what scientists don't agree on are the biological mechanisms that might underlie its harmful effects on reproductive systems.
Animal studies give some clues.
Rat study findings have also picked up on an association between dioxin exposure and undescended testicles. Exposure in utero and through breast milk has altered spermatogenesis and delayed the descent of the testes, according to Hauser. Finally, a small human study also found lowered testosterone in workers exposed to dioxin, Hauser says. Sadly, Chapaevsk offers a clear-cut case of human exposure to dioxin. Revich and others have found dioxin levels in the soil as high as those in parts of Vietnam doused with the dioxin-laden defoliant, Agent Orange.