Marine Pollution of PCBs and DDT in the Seas around Japan - May 1998

Marine Pollution of PCBs and DDT in the Seas around Japan - May 1998

According to a survey conducted in 1998 by a research team from Ehime University, toxic chemicals such as polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) were detected at high concentrations in the bodies of God whale and killer whales caught in the waters around Japan, particularly in the Seto Inland Sea and off the western coast of Kyushu. The fat of killer whales contained 400 micrograms of PCBs per gram, a concentration approximately 4,000 times higher than that found in land animals. In addition, 200 micrograms of DDT were also detected in the Gondola whale, highlighting the seriousness of environmental pollution.

Inadequate waste disposal in developing Asian countries, particularly China and Indonesia, has been pointed out as the cause of this contamination. In these countries, disposal of electrical equipment and pesticides is not properly managed, and PCBs and DDT are released into the air, rivers, and oceans. These chemicals reach the seas around Japan by the Kuroshio Current and other ocean currents, and accumulate in marine organisms in the Seto Inland Sea and off the coast of Kyushu.

In addition, PCBs used in the past in Japan have not been properly disposed of and may be affecting the water quality around Tokyo Bay. PCBs contained in electrical equipment and building materials discarded in the 1970s are particularly problematic, and inadequate waste management in Japan is also a contributing factor to the contamination.

In response to the findings of this study, the Ministry of the Environment is strengthening monitoring of the waters around Japan and taking measures to prevent the spread of contamination by PCBs and DDT.