In retrospect, it's clear that previous ecological problems have also hinged upon endocrine disrupters. In the 1960s, as Rachel Carson warned of the ecological effects of pesticides (see "Silent Spring" in the bibliography), scientists began wondering why eagles, peregrine falcons and similar birds were not reproducing.

Eventually, the focus narrowed to the large number of broken eggs being found in eagle nests, an effect that was blamed on the pesticide DDT. Carson herself singled out DDT as the likely culprit in eagle eradication, and noted that "the insecticidal poison affects a generation once removed from initial contact with it." Right she was. According to Judith Weis, a biologist at Rutgers University, it's likely that the pesticide disrupted the eagle's endocrine system, interfering with calcium metabolism and producing weak egg shells did not protect the developing offspring.

So the case is closed?
Not exactly. The effects of some endocrine disrupters on some animals are pretty clear, but complicating factors remain. For example, some plants produce large amounts of estrogens, to which animals are exposed in large quantities. To skeptics, this undercuts the argument against synthetic chemicals, since we're exposed to much larger amounts of the natural estrogen mimics. But, as Weis notes, these "phytoestrogens" are not necessarily endocrine disrupters.

There's no question that some plant-produced hormones do affect people: Women have used certain plants to regulate fertility for centuries. But it's also possible that since we have evolved in a plant-dominated world, our bodies have "learned" to either ignore or break down these "natural" endocrine disrupters.

The scientist as advocate
Just as modern environmentalism owes a debt to a woman scientist (Rachel Carson) and a single book (Silent Spring), the growing furor over endocrine disrupters is in large measure the work of Theo Colborn, an ecologist, and "Our Stolen Future," a book she wrote with Dianne Dumanoski and John Peterson Myers (see the bibliography).

Colborn became concerned about endocrine disrupters when she looked at deformities in animals in the Great Lakes region, and then expanded her search to the larger effects of these chemicals.

The group's consensus statement maintained that "Some of the developmental impairments reported in humans today are seen in adult offspring of parents exposed to synthetic hormone disrupters ... released in the environment." The authors also noted that the concentrations of several hormone disrupters in Americans are about the same as the levels found in wildlife where hormone disrupter damage was evident.

So how is EPA going to protect us from this danger -- if it is a danger?