Clean Watershed Campaign

Dioxin – A Serious Public Heath Risk

“Dioxin – A Serious Public Health Risk”

Stephen Lester, Science Director
Center for Health, Environment & Justice

Many industry advocates have argued that dioxin is not a threat to public health and that the federal EPA’s proposed cleanup goals – interim preliminary remediation goals (PRGs) – for dioxin in soil are trying to solve a problem that doesn’t exist. I could not disagree more. These industry advocates conveniently ignore the scientific facts about the toxicity of dioxin.

The truth about dioxin is that it is one of the most potent carcinogens ever tested by the U.S. National Toxicology Program who has determined that the most toxic form of dioxin known as TCDD is a human carcinogen. In addition, the World Health Organization’s International Agency for Research on Cancer (IARC), the most prestigious cancer research group in the world, has evaluated the cancer risks posed by exposure to dioxin and concluded that TCDD is carcinogenic to humans. These are facts that industry advocates refuse to accept.

In its recent draft report on dioxin, EPA calculated the cancer risk to be between 0.5×10-4 and 2.7×10-4, more than 200 times greater than the one-in-a-million cancer risk considered acceptable for the general population. These risk numbers are not some shoot-from-the-hip guess, but a careful calculation that follows the most accepted and advanced methods for estimating cancer risks.
This is another fact that industry advocates refuse to accept.

Dioxin causes neurodevelopmental, immune, and reproductive effects at extraordinarily low levels, not the typically high levels found in laboratory and occupational studies. The studies documenting these effects have been conducted in world class research centers including in the Netherlands, Italy, and here in the United States. More facts that industry advocates refuse to accept.

The U.S. Veterans Administration, following the recommendations of a committee of the National Academy of Sciences Institute of Medicine, has concluded that there is sufficient evidence to pay claims made by veterans who served in Vietnam who were exposed to dioxin in Agent Orange for a host of diseases including soft tissue sarcoma, Non-Hodgkin’s lymphoma, Hodgkin’s disease, chronic lymphocytic leukemia, chloracne, diabetes, prostate cancer, multiple myeloma, Parkinson’s disease, hypertension and spina bifida in offspring. Still more facts that industry advocates refuse to accept.

EPA recently calculated a reference dose for dioxin for the first time. A reference dose is considered a “safe” dose, one that would not expect to cause any adverse health effects. Previously, the agency had refused to calculate a reference dose because it felt it was meaningless since the average person in the U.S. was already being exposure to more than this “safe” dose. They have now confirmed what they suspected. Industry advocates may choose not to believe these risk estimates, but that does not mean that the risk estimates are inaccurate or that the level of dioxin that the average American is exposed to is a safe level.

Levels of dioxin may be going down in the environment and in human blood, but these levels are still too high. According to a recent analysis by the Environmental Working Group, the average dioxin level found in nursing infant blood is 77 times greater than the EPA’s newly calculated “safe” reference dose. If we believe the scientific methods we use to assess risks in this country, then we have to accept the risk numbers for both cancer and non-cancer effects derived by EPA in their most recent reassessment report.

This is especially true in light of the increasing rates of learning disabilities, developmental, immune, and reproductive problems that are occurring in children. Dioxin may not be the sole cause of these increases, but it would be wrong to ignore its contribution. It’s time we acknowledged the facts about dioxin and take it for what it is – a serious public heath threat that we cannot afford to ignore.

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Stephen Lester,
Science Director
Stephen has a Master’s of Science, in Toxicology, from Harvard University, and a second Master’s of Science, in Environmental Health, from New York University. He received his Bachelor’s of Science in Biology from American University. Stephen has served on numerous scientific advisory and peer review committees including at the Natural Resource Council of the National Academy of Sciences, the National institutes of Environmental Health Sciences, and the Congressional Office of Technology Assessment.