Dioxin: death for objectivity

Compensation schemes for vets exposed to Agent Orange fly in the face of the evidence.

Shortly before hurricane Katrina struck Mississippi, a devastating jury decision there struck the company DuPont, awarding a man $15million because of his scientifically groundless claim to have been injured by the chemical dioxin.

This was only the latest in a long line of bogus assaults on dioxin. Greenpeace and other environmental organisations damn the US Environmental Protection Agency (EPA) for moving too slowly to eliminate dioxin from meat and dairy products, air and water, and, most poignantly, from mothers' milk. Greenpeace says that dioxin causes cancer, miscarriages and birth defects, developmental disorders and lasting mental impairment. Despite moving too slowly for Greenpeace, however, EPA agrees that dioxin must be carefully regulated. And the Department of Veterans Affairs (VA) pays millions of dollars to thousands of veterans each year as compensation for the diseases ostensibly caused by the dioxin that contaminated Agent Orange.

Greenpeace, EPA and VA cite the results of hundreds of animal tests to bolster their claims about dioxin's deadliness. But they ignore or downplay the absence of human evidence for harmful effects.

That absence is not from lack of trying to find human effects. EPA, VA, the US Department of Health and Human Services, the International Agency for Research on Cancer, the Occupational Safety and Health Administration, the National Institute of Occupational Safety and Health, the United States Air Force, state agencies, and industry, have all spent millions studying populations of people who have been or might have been exposed to dioxin.

Sifting through the results of studies of workers exposed to high levels of dioxin reveals scattered reports of a particular cancer or disease being found at above-expected levels in one study or another. It also reveals that some cancers or diseases are found at below-expected levels in some studies. There's little consistency - cancers elevated in some studies are decreased in others.

The results support the conclusion that dioxin exposures to human populations are without effect, and that the sporadically found higher and lower disease rates are the result of random fluctuations in disease occurrence. Even the International Agency for Research on Cancer's (IARC) widely proclaimed assessment that dioxin causes cancer in humans relies on animal test results; IARC concedes the evidence from studies of humans is less than convincing.

What the dioxin studies really tell us

There are fewer studies of 'environmentally exposed' people, primarily because there are few populations that have been exposed to higher than 'background' levels. The two most studied populations are those that lived around a chemical plant in Seveso, Italy, which blew up in 1976; and the residents of Times Beach, Missouri, which was exposed to dioxin-contaminated oil. These studies find that there are no increases in overall disease rates or cancers. It is possible to associate dioxin exposures with elevated occurrence of a specific cancer or disease in some studies, but the occurrence of other cancers and diseases is lower than expected, and there is little consistency among studies' results. This suggests that the varying disease rates result from fluctuations of occurrence observed whenever small populations are studied.

The most publicised dioxin-exposed group is Vietnam veterans. Agent Orange, a mixture of two herbicides, was used to defoliate trees in the jungles of Vietnam. It was always contaminated with traces of dioxin, present at levels from less than one part per million to perhaps 50 parts per million, so anyone exposed to Agent Orange was exposed to dioxin. Dioxin persists for years in the fatty tissues of animals, and measuring current levels of dioxin in those tissues provides information about past exposures to dioxin and dioxin-containing substances, such as Agent Orange.

The two active ingredients of Agent Orange are far less toxic than dioxin in animal tests, but one was removed from the market because it was always contaminated with dioxin. The other is still available in any hardware store.

The ranch hands

Two groups of Vietnam veterans have been intensely studied. The 'Ranch Hands' are the 1,200 Air Force personnel who serviced and flew the airplanes that sprayed 90 percent of the Agent Orange used in Vietnam. Along with 1,200 other Air Force personnel - a control group referred to as 'Comparisons', who were not exposed to Agent Orange - they were subjected to a week-long physical and psychological examination every five years between 1982 and 2002. This finds no difference in overall disease or mortality rates between the Ranch Hands and Comparisons

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