A new exposâ€š points out the threat of chemical pollutants that mimic the hormones in our bodies, undercutting the natural cycles of growing organisms. Dumanoski is a science reporter for the Boston Globe; Colborn and Myers are two of the environmental scientists who have pioneered the study of the biological effects of pollution. In the late 1980s, while studying the effects of pollution on the Great Lakes, Colborn began to recognize a pattern: the impairment of reproductive or growth cycles in various organisms. The evidence includes gull populations in which males are so scarce that females have taken to nesting together, eagles that have lost interest in mating, and alligators with deformed sexual organs. The culprits were PCBs, dioxin, DDE (a DDT breakdown product)--persistent chemicals that concentrate in the body fat of animals toward the top of the food chain and, ultimately, in human beings. Despite efforts to ban use of the chemicals, they are already ubiquitous in the environment--in everything from arctic ice to mother's milk--and some of them will not break down for centuries. Several studies indicate lowered sperm counts in human males over the last 50 years, quite possibly an effect of the increased use of the suspected chemicals. Dumanoski effectively dramatizes the story of Colborn's findings, explaining both the biochemical reactions and their environmental importance. On the difficult question of how to combat the pervasive threat, the authors have several suggestions: monitoring the quality of drinking water, not eating fish from waters known to be contaminated, avoiding animal fat in the diet, eating organic produce, avoiding contact between food and plastics. On a governmental level, increasing vigilance and regulation is a step in the right direction. The authors' warning may seem alarmist to many, but in view of the potential threat to humanity as a whole, it would be folly to ignore it.