S. M. Whitaker and L. B. Willett1
The Ohio State University Department of Animal Sciences
Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) are two related families of organochlorine compounds that are often referred to collectively as dioxins or furans. These families of persistent and lipophilic chemicals recently have become very important in environmental and health evaluations. These compounds are easily formed as unwanted by-products of many commercial reactions, and they have become widespread throughout our environment. Polychlorinated dibenzo-p-dioxins and PCDF are extremely lipophilic, resistant to degradation, and accumulate within the fat of animals and humans alike. Once these chemicals are released into the environment or taken up by biological tissues, they are extremely difficult to eliminate. Lactation is the most efficient route of excretion. The toxicity of these compounds are species and chemical-structure (congener) specific. The 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD) congener is considered to be the most toxic of all of the PCDD and PCDF congeners. Even small amounts of exposure to this congener can have serious health repercussions. Other PCDD and PCDF congeners are not as toxic as TCDD, but they also are toxic in small doses. The relative toxicity of these congeners is rated by International Toxic Equivalent Factors (I-TEF). Exposure to these chemicals should be kept as low as possible due to their potential health risks. Some of the health effects seen with exposure to these compounds have been liver enlargement, liver lesions, immunotoxicity, a wasting syndrome, thymic and spleen atrophy, tissue specific hypo- and hyperplastic responses, carcinogenesis, endocrine disruption, and, in extreme cases, death. Much more research is needed to understand the movement of these environmental chemicals through food-producing livestock and into human foods.
1 For more information, contact at: The Ohio State University, Ohio Agricultural Research and Development Center, 128 Gerlaugh Hall, 1680 Madison Avenue, Wooster OH 44691, 303-263-3792, Fax 330-263-3949, e-mail: willett.2@osu.edu