Polychlorinated terphenyls as an environmental pollutant in Japan.

This paper summarizes the results of the studies made by our group and other investigators in Japan on the residue levels of polychlorinated terphenyls (PCTs) in a variety of items in the environment including the human body. In contrast to widespread distribution of PCBs in the environment, PCT residues were seldom found in samples from aquatic environments such as water and sludge and waterfowl and fish, and, if found, the levels of PCTs were so low as to be practically negligible. Similarly, no significant levels of PCTs were detectable in foodstuffs such as edible oils, vegetables, dairy products and meat and in prepared diets. These findings may be explained by the fact that PCTs are much less volatile and soluble than PCBs and the total industrial output of PCTs was as small as 2700 tonnes which is 1/20 of PCBs produced in Japan. However, the levels of PCTs in human fat and blood were shown to be almost equivalent to PCBs, despite a negligible amount of PCTs being found in food. No clear explanation of human contamination by PCTs has been proposed so far.