Persistent polyhalogenated environmental chemicals. 1. Polychlorinated biphenyls (PCB) [in milk and milk products]
1997
Bluethgen, A. | Heeschen, W.H. (Federal Dairy Research Centre, Kiel (Germany)) | Burt, R.
The estimates for the industrial production of PCBs and the release into the environment differ widely and range up to 2.4 million metric tons for production and up to 200,000 metric tons released into the environment from human activities. These large figures in combination with the chemical and physical properties of PCBs have led to an appreciable worldwide contamination of the environment, biota and food-producing ecosystems. The congener-specific combination of stability against biotic and non-biotic degradation and lipophilic properties have lead to an accumulation process in the food chain of several orders of magnitude from atmosphere, soil and water in the final depot: the human adipose tissue. Milk fat contaminated through uptake of PCBs by the dairy animal from the atmospheric contamination. In addition to these diffuse sources of contamination and the reservoir in the soil, a few point sources may be responsible for the local high contamination of milk fat with PCBs. Though their chronic toxicity to warmblooded animals is low, a few congeners exhibit pharmacodynamic properties such as immune suppression or act as epigenetic carcinogens in mammals. Some countries have legislation on PCBs in food, mainly fatty food of animal origin. As for every contaminant, source-directed measures should be given high priority to reduce consumer exposure. Since the worldwide ban of PCBs in open systems in 1972, the contamination levels in food have been decreasing appreciably, but PCBs are expected to continue to be found at low levels for many years.
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