1. PCB and dioxin
Polychlorinated biphenyl (PCB) is a mixture of synthetic organic chemicals extensively used in hundreds of industrial and commercial applications. The widespread utility is due to its characteristics, such as electrical insulating properties, incombustibility, high boiling point, and chemical stability to acid and alkali. However, since 1972, prohibition on the manufacture of PCB has long been implemented in Japan because of prevailing concerns over its toxic effects and persistence in the environment. Consequently, the treatment of PCB essentially maintained in various places and the measures against the contaminated soil are needed promptly.
On the other hand, dioxin is another highly persistent chemical, which is diffused into the environment by combustion. It is formed by burning chlorine-based chemical compounds with hydrocarbon and is an unintentional by-product of industrial processes, such as garbage incineration and from the electric furnace used in the manufacture of steel. Indeed, PCB and some agricultural chemicals containing dioxin as impurities are possibly accumulating continuously into the environment just like a mud on the bottom of a lake, etc.
This condition remains a threat to both our health and our environment. Hence, the “Law Concerning Special Measures against Dioxins" defines polychlorinated dibenzo-para-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF), including coplanar PCB* as "dioxins".
2. Government regulation in Japan
The environmental standards (refer to Table 1) concerning contamination of PCB on water, groundwater, and soil are identified. In addition, the elution standards and content standards are stipulated as third-class specification toxic substance in the “Soil Contamination Countermeasures Law” (May 2002 proclamation)1). We must keep it in mind when treating polluted soil.
The official declaration as regards the terms for disposal and storage conditions, as well as the duties of a PCB waste storage entrepreneur, PCB manufacturer, and the role of the national and local governments is identified in "Law Concerning Special Measures Against PCB Waste" (June 2001 proclamation). The types of PCB wastes, collection and conveyance, disposal methods, and acceptance standards for the last waste disposal place are stated in " Waste Disposal and Public Cleansing Law (Law No.137 of 1970) " (December 1970 proclamation). This law also places emphasis on the treatment of PCB-polluted soil.