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The health effects associated with dioxins depend on a variety of factors including: the level of exposure, the age at which one was exposed, and how long and how often. People exposed to very large amounts of dioxins develop chloracne, a severe skin disease. However, even in minute amounts dioxins act as human carcinogens. And numerous animal studies indicate that exposure to low levels of dioxins over long periods (or high level exposures at sensitive times) may result in reproductive, developmental, and behavioral effects as well as a weakened immune system. Fetuses, infants, and children may be more sensitive to dioxin exposure because of their rapid growth and development. For cancer, EPA has calculated a range of estimates of the risk to Americans and the results raise concerns. EPA has estimated that the risk to general public of contracting cancer due to dioxin exposure may be as high as 1 in 100. And, for other health impacts, the EPA estimates that the amount of dioxin found in the tissues of the general human population closely approaches (within a factor of 10) the levels at which adverse effects are known to occur in monkeys and other animals, both wild and laboratory-bred. Many people have more elevated exposures to dioxin as a result of food contamination incidents, through workplace exposure, or through industrial accidents. Entire communities, especially those in the far north, suffer elevated exposures as a result of the extraordinary levels of dioxin in the fish, meat, or dairy products upon which they depend. Over the last decade there have been demands, especially by certain industries, that full scientific certainty of adverse effects should be attained before the US EPA takes any decisive action to curtail dioxin sources. Unfortunately, there is no way for scientists to perform the "definitive" experiment, to compare exposed and unexposed populations in the field, because all creatures, great and small, and all people have already been exposed to dioxins. Nevertheless, the weight of scientific evidence that dioxins are damaging life of earth is overwhelming. The environmental community nationally and internationally has urged a precautionary approach, one fully supported by the Sierra Club's Eliminating Planetary Pollutants Campaign. The Precautionary Principle states that where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing measures to prevent environmental degradation (more on Precautionary Principle). For additional information, please see The People's Dioxin Report from the Center for Health, Environment and Justice; order a copy by calling 703-237-2249. Also see the U.S. Interagency Working Group, Dioxin Frequently Asked Questions. For the Science Advisorie Board's (SAB) Draft Report, Review of Revised Sections of Office of Research and Develpoment's (ORD) Reassessment of Dioxin, March 13, 2001, please visit the USEPA's website. References used in preparing this fact sheet are noted in the above text with links provided for your convenience.The report could lead to further limits on the amount of fish people can safely consume. Photo of caribou courtesy Douglas Canfield 2001 Up to Top HOME | Email Signup | About Us | Contact Us | Terms of Use | © 2008 Sierra Club |
"Dioxins" are a group of chemical compounds with similar chemical structures and a similar mode of action in organisms. The several hundred different dioxins are members of three closely relatedchemical families: dioxins, furans, and certain PCBs (polychlorinated biphenyls). Dioxins and furans are not produced intentionally, but are inadvertent byproducts of manufacturing and incineration. PCBs are a man-made chemical product and, although they remain in use in the U.S., they are no longer manufactured here.
Because dioxins have spread throughout the environment, because they concentrate in polar regions, and because they build up in the food chain, almost every creature on the planet, including humans, carries some level of dioxin in their bodies. For humans, EPA estimates that most dioxin exposure occurs through the diet, with over 95% eating animal fats found in meat and fish, lard and fish oils, dairy products, and eggs. People and other mammals are also exposed prenatally to dioxin released from the mother's body and via breast-milk. Although breast milk appears to be a significant source of dioxin exposure for nursing infants, the overwhelming body of scientific evidence supports the health benefits of breast-feeding for humans despite the risks posed by dioxins (
The risk to other young mammals whose mothers may carry more dioxin in their bodies and who may be more sensitive to its ill effects are not well known, but existing information is deeply troubling. A recent survey of hunters and elders in far north Canada on the health of wildlife populations exposed to high levels of pollutants revealed that every hunting community surveyed had observed abnormalities in at least one of the species they harvest regularly, including the caribou, seal, walrus, beluga whale, narwhale and polar bear (