2. Gulf War Syndrome

3. Chemical weapons in history

4. The nerve of this gas

5. Agent Orange revisited

6. Dioxin on trial

7. Most poisonous substance?

Update: Gulf War Syndrome

Parts per trillion couldn't hurt, could they?
Does dioxin cause "only" cancers and chloracne, as the Institute of Medicine reported? Not according to Arnold Schecter, professor of preventive medicine at the State University of New York Health Science Center in Binghamton.

A dose-response curve shows the response from a given dose. If the curve is "linear," any dose carries some risk, and increasing the dose raises the risk. If the curve is "non-linear," doses below the "threshold" are safe.

Schecter, who has studied this family of chemicals for 15 years and edited a 1994 book, "Dioxins and Health" (see bibliography), says, "The scientific literature [on dioxin] is changing very rapidly and demonstrating more human health effects."

A key dispute concerns the shape of dioxin's curve. If the curve is straight at low doses, no dose is safe. But if there's a threshold, then low doses may be safe.

One reason for underestimating dioxin's effects, Schecter says, is that early studies improperly classified exposures. Scientists used to assume that all members of some groups were exposed, and members of other groups -- typically civilians, in the case of agent-orange studies -- were not. Schecter says his research team found, in a 1983 study, that every American they tested carried traces of the chemical: "The entire population is contaminated with dioxin."

If so, that undermines comparisons between U.S. Vietnam veterans (who supposedly all had dioxin exposure) and civilians (a control group presumed to be unexposed). "It was a big surprise," Schecter says, and an unwelcome one.

So dioxin research is a black hole of ignorance...