Tittabawassee River Watch Editorial
Dioxin exposure in perspective Friday, January 27, 2006 Editor, The News: Letter writer Richard A. Maltby ("Dioxin dangers," Jan. 19) quotes extensively from a draft EPA dioxin reassessment document. The EPA document has remained in draft form for more than a decade because of disagreements in the scientific community regarding both cancer and non-cancer health effects. The National Academy of Sciences is completing a critical review of the draft EPA document and is expected to release a report this year. Maltby doesn't address the important issue of relative levels of dioxin exposure. While studies of humans have provided inconsistent evidence on nearly all health effects of potential concern, the one thing these studies all have in common is that they focus on people who have had substantial exposures to dioxins through direct contact with chemical products in a manufacturing or occupational environment, or after catastrophic accidents in which large quantities of dioxins were released. No consistent health effects, other than chloracne in some groups, are observed in studies of these persons with relatively high exposures. Since 1967, Dow has published 20 studies on potential human health effects of high levels of dioxin exposure among 2,192 of its employees. The studies individually and together demonstrate that even highly exposed employees generally do not have a greater risk of disease, with the exception of chloracne that occurred in workers who experienced very high exposure levels. These chloracne cases resolved themselves within a few years. Dose-response is a fundamental principle of medicine: One-tenth of an aspirin will cause little or no response if ingested; an aspirin taken per day may help prevent a heart attack; 10 aspirin tablets taken at once may cause stomach bleeding. But 100 aspirin tablets sitting in a bottle on the shelf will cause no effect, and neither will dioxins or furans in soil. All persons in the United States and other industrialized countries are exposed to trace levels of dioxins and furans in food. But these exposures, and possible exposure in local soils, are low. International public health authorities, including the U.S. Centers for Disease Control and Prevention, have concluded that low environmental exposure to dioxins or furans are not likely to exceed a threshold needed to cause cancer or other health effects. Dow acknowledges the concerns of the residents in Midland and the Tittabawassee River valley regarding the dioxin and furan contaminants in soils in the area. However, it is essential that everyone have a firm grasp of the scientific information, in proper context, to ensure informed decisions about personal health and safety. James J. Collins director of epidemiology, Dow Chemical Co. Midland
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