From environment to food: the case of PCB.

Polychlorinated biphenyls (PCB) are ubiquitous microcontaminants. Because of both lipid solubility and the absence of adequate metabolic pathway in the organisms, PCB tend to bioaccumulate along the trophic chains. PCB may affect the endocrine, nervous and immune systems; the biological activities are related to chemical structure, particular concern has arisen about a group of 'dioxin-like' congeners. Feed is the major way of PCB exposure of farm animals. PCB bioaccumulation is related to the lipid content of tissues, particularly in fat tissues, in meat, liver and are transferred into milk and eggs. More than 90% of human exposure derives from foods of animal origin. A recent episode of PCB contaminating pastures occurring in the industrial municipality of Brescia (Northern Italy) is presented as an example of feed-food-human transfer chain. Farm animals and human exposure to dioxin-like and non dioxin-like PCB congeners is discussed in relationship to their toxicological effects, with special attention to vulnerable groups, such as children. Finally, considerations on risk assessment and management are reported.