The dioxin debate: the EPA maintains that dioxin is one of the most carcinogenic substances known to man. But the National Academy of Sciences casts doubt on that assessment.

In summer months, hikers, bikers, and families looking for a nice place for a picnic visit the park where Times Beach, Missouri, used to be. Yet, just two decades ago, the area was deemed unfit for human habitation and the residents of Times Beach were evacuated. What went wrong?

The answer is government went wrong. Based on rumors that horses in the area had died under strange circumstances, investigators from the Environmental Protection Agency arrived in the town to conduct tests. By 1982, they had concluded that the town suffered from elevated levels of dioxin, a compound the EPA still claims is one of the most carcinogenic (cancer-causing) substances known. In what the agency still calls "a dramatic move for safety," the EPA "blocked off roads to the town ... and placed security guards to patrol the site around the clock." The residents were "evacuated" and the town razed at a cost of more than $32 million. The Times Beach dioxin affair was unprecedented and unnecessary.

Common Chemicals

The word "dioxin" actually refers to a class or family of similar compounds that are common byproducts of combustion and several industrial processes, including paper making and the manufacture of some pesticides, herbicides, defoliating agents (like agent orange), and some cleaners. Because it stems from such commonplace activities, most people experience some level of dioxin exposure, usually with little effect.

Very high doses can cause problems. The most common symptom of exposure to high levels of dioxin is the condition known as chloroacne in which the victim experiences severe eruptions of ache, usually on the head and face. The most recent high-profile example is the strange poisoning of Ukrainian politician Viktor Yushchenko (shown above). In 2004, at the time a candidate for the Ukrainian presidency, Yushchenko was exposed to a dose of dioxin 6,000 times higher than normal. In his public appearances afterward, his face was pocked and swollen. One might have expected him to develop cancer and die if dioxin were as lethal as the EPA suggests. On the contrary, Yushchenko, now president of the Ukraine, survived.

Moreover, the supposed relationship between dioxin and cancer is wildly overstated. There have been no dioxin-related deaths among former residents of Times Beach. In fact, Vernon Houk, the Centers for Disease Control (CDC) official who in 1982 recommended that Times Beach be abandoned, later admitted that the move was an overreaction. "I would not be concerned about the levels of dioxin at Times Beach," he stated in 1991, noting that it "is becoming more and more accepted around the world" that low doses of dioxin are not as dangerous as previously believed.

Taking the EPA to Task

That conclusion seems to be supported by a recent review by the National Academy of Sciences (NAS) of the EPA's dioxin reassessment. The NAS's National Research Committee concluded that the EPA had overstated the case for dioxin's link to cancer. While the National Research Committee used caution and stated that there might be a possible link between dioxin and cancer, "The committee found that the argument provided by EPA ... to support its position that the epidemiological data met the criterion of 'strong evidence of an association' between dioxin exposure and cancer risk was unconvincing."

According to experts, the reason the EPA has misrepresented dioxin's link to cancer lies in the agency's dogmatic and unscientific manner of reasoning. According to Dr. Gilbert Ross of the American Council on Science and Health, "The long-standing policy at the EPA has been to evaluate chemical toxicity as if even the tiniest, barely measurable dose of a substance might still cause cancer (or other health effects) if it can be shown to do so when fed to rats at high doses."

Of course, it is not true that a low dose of a substance must be harmful if a high dose of the same substance causes harm. Consider water, for instance. Ingesting more than three quarts of water at one time can prove extremely harmful to some people, yet we'd die without it.

Water intoxication is rare, but it does occur. In the summer of 2003, for instance, British actor Anthony Andrews was hospitalized for just such an overdose. The point is that in high enough concentrations, nearly anything can be toxic. As medieval physician and polymath Paracelsus observed, "All substances are poisons; there is none which is not a poison. The right dose differentiates a poison." It's a lesson the residents of Times Beach probably wish the EPA had learned decades ago.