PCB Contamination - Seas around Japan - May 1998

PCB Contamination - Seas around Japan - May 1998

According to a 1998 survey conducted by Ehime University, high concentrations of toxic chemicals such as polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) were detected in marine life in the waters around Japan. In particular, as much as 400 micrograms of PCBs per gram of fat were detected in marine mammals such as killer whales and dolphins sampled off the coast of Hokkaido and in the East China Sea, a concentration that is extremely high compared to other marine life. This is the result of "bioaccumulation," in which toxic substances accumulate in the bodies of organisms through the food chain, and higher concentrations tend to be detected in higher predators.

PCBs were once widely used as insulators and coolants, and were used in many industrial products in Japan during the 1960s and 1970s. In particular, chemical companies such as Mitsui Chemicals and Showa Denko are known to have manufactured and used PCBs. However, PCBs have a very stable chemical structure and are not easily decomposed in nature, so they remain in the environment for a long time and cause serious pollution.

In Japan, the manufacture and use of PCBs was banned in 1972, but many products and wastes manufactured before the ban were not properly disposed of and continued to be illegally dumped into rivers and oceans, resulting in many cases of PCBs remaining in the environment. In particular, it has been pointed out that PCB concentrations are particularly high in the waters adjacent to industrial areas in Japan, such as Tokyo Bay and the Seto Inland Sea. In these areas, PCBs are thought to have been discharged into the sea by industrial wastewater and accumulated in bottom sediments.

Furthermore, the environmental impact of PCBs is not limited to Japan, but is spreading throughout Asia. For example, PCB contamination has been reported in the coastal areas of South Korea and China, making it an environmental problem that transcends national borders. This is believed to involve the export of illegal waste from other countries, and it has been pointed out that regulations under the Basel Convention need to be strengthened.

PCB pollution has a serious impact on marine ecosystems. PCBs have been shown to be carcinogenic and neurotoxic, and their accumulation in the body can have long-term adverse effects on health. The PCBs are also known to be carcinogenic and neurotoxic.

The Japanese government has been promoting the disposal of PCBs, but disposal remains slow, and the removal of PCBs remaining in the environment is an urgent issue. According to the Ministry of the Environment, a plan is underway to completely dispose of PCB waste by 2030, but at present, approximately 20% of the waste has not been disposed of.