Whiteside uses the pendulum as metaphor, but the toxic cloud was real. On July 10, 1976, at a chemical factory near the town of Seveso, Italy, there occurred an accident involving a herbicide commonly abbreviated 2,4,5-T. An explosion threw up a cloud containing an extremely poisonous chemical contaminant associated with 2,4,5-T and called dioxin. This toxic cloud settled over some 700 acres inhabited by about 5,000, turning a minor industrial accident into a major environmental disaster.

Nobody with responsibility comes off well in Thomas Whiteside's view of the way the disaster was handled. The chemical company (ICMESA) waited two weeks before acknowledging dioxin contamination sufficient to warrant evacuation of all inhabitants from the most seriously affected zones.

With almost clinical detachment, Whiteside recounts his two visits to Seveso and what he observed: The tragic uprooting of 739 people from their homes; the widespread cases of cloracne, burnlike skin lesions, "the sure mark of dioxin poisoning," which particularly affected children; the fear of fetal malformations which led many women to seek, and receive, the Catholic Church's permission for therapeutic abortions; the unpredented clean-up efforts; and the tragic economic consequences for the people.

Many readers will recall that 2,4,5-T was the herbicide called "Agent Orange" which was extensively sprayed by the American military over South Vietnam. Biological scientists were then, and are now, deeply concerned because residues of the highly toxic dioxin appear to have entered the human food chain. And there is evidence from industrial accidents in many countries suggesting the dioxin is a carcinogen, and that it can cause liver damage, birth defects and miscarriages.

Whiteside concludes that the issue of 2,4,5-T is "a sort of regulatory touchstone concerning the appropriate and permanent measures of control that clearly need to be undertaken to cut or eliminate the flow of such toxic substances into our environment." (Yale, paperback, $4.95, cloth $15)