Is EPA ready for the truth about dioxin?

Published July 1, 2002

In late May, the Environmental Protection Agency issued its annual Toxic Release Inventory (TRI) report on the amount of toxic chemicals released into the environment. This year’s report contained some genuinely good news, which probably explains why it got little attention in the press. It notes, for example, that chemical releases fell nearly 10 percent from 1999 to 2000 and are down some 48 percent since 1988.

Most surprising about the report is what it did not say: It did not bash American industry for releasing dioxins, long described by environmentalists as the “deadliest chemical known to man.” This was the first TRI to include dioxins, and many people in industry had feared it would be used as an opportunity to pummel businesses.

How deadly?

Dioxins are a group of chemical compounds that can be released by such human activities as trash burning, metal smelting, fuel burning, and the bleaching of paper pulp. Natural sources of dioxins, such as volcanic eruptions and forest fires, probably dwarf emissions caused by human activities.

Dioxins’ reputation as deadly chemicals arose from tests on laboratory animals, where it was discovered that even tiny amounts (just six micrograms per kilogram of body weight) could kill guinea pigs. Other kinds of rodents proved to be much more resistant. (Hamsters, for example, require between 2,000 and 5,000 times the dose to achieve the same mortality rate.) Ten thousand studies later, it is now generally believed that exposure to low levels of dioxins does not present an appreciable human health risk.

The Environmental Protection Agency in 1994 attempted to label dioxins a “known human carcinogen,” but its own scientific advisors rejected such a conclusion. In June 2000, EPA tried again, claiming the cancer risk from dioxins exposure is 10 times higher than the agency reported in 1994. But EPA also said the risk could be zero, and the agency’s “draft assessment” still hasn’t been formally released.

EPA’s past dioxin-phobia

EPA’s 2000 risk assessment was completely out of line with assessments conducted by government and scientific agencies in the rest of the world. EPA modeling resulted in an estimated “safe” daily intake of dioxins between 100 and 1,000 times lower than safe intake levels as determined by the U.S. Agency for Toxic Substances and Disease Registry, Canada, Japan, the European Commission Scientific Committee on Food, and the Joint United Nations Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives.

EPA’s proposed standard for dioxins is so extreme that practically no foods could pass the test. Scientific analysis of Ben & Jerry’s “World’s Best Vanilla” ice cream, for example, showed it had 200 times the level of dioxins considered by EPA to be safe. Indeed, the EPA risk assessment holds that human exposure to dioxins in the natural environment is 100 times higher than “safe” human exposure levels!

In the past, EPA fueled unreasonable public fear of dioxins by failing to report that exposure is far more likely to come from natural or non-industrial sources than from industry. For example, backyard trash burning is currently the largest identifiable source of human dioxin emissions. Emissions from industry sources fell some 80 percent between 1987 and 1995 and are expected to fall another 66 percent by 2004.

No more scare tactics?

An EPA report that doesn’t cry “wolf” over chemical emissions is noteworthy indeed. Is it a sign that EPA is moving away from scare tactics and extremism? We can only hope.

In both the news release and executive summary of the report, EPA cautions that “TRI reports reflect releases and other waste management activities of chemicals, not exposures of the public to those chemicals. Release estimates alone are not sufficient to determine exposure or to calculate potential adverse effects on human health and the environment.”

This is an important message that belongs at the beginning of the two documents mentioned, rather than at their very ends where, in fact, it appears. Many experts believe the TRI is a nearly useless exercise because it reports on chemicals that are never released to the environment. TRI also fails to distinguish emissions that may threaten human health from those that do not, or to weigh emissions by their toxicity.

Compared to past rhetoric from EPA, however, it is a sign of progress that this common-sense message appears at all.

For more information …

on EPA’s Toxic Release Inventory, go to