Regulations for Cadmium in Rice and Soil in Japan and Countermeasures to Reduce the Concentrations

Abstract

Rapid industrialization in the 1960s caused serious heavy metal pollution of arable soils, particularly paddy soils in some regions of Japan. The Agricultural Land Soil Pollution Prevention Law in Japan was enacted in 1970 to address heavy metal pollution. Cadmium (Cd), arsenic (As), and copper (Cu) were designated as hazardous substances targeted for regulation. Cd has been recognized as one of the most detrimental elements in Japan, due to the so-called itai-itai disease caused by Cd ingestion. Recently, the Codex Alimentarius Commission proposed the maximum permissible concentration of Cd in polished rice and other relevant crops. This chapter provides an overview of the regulation pertaining to Cd for soil and rice in Japan and some foreign countries. The physicochemical processes and behavior of metals in soils are described. The following conventional and advanced technologies to mitigate soil Cd contamination are also presented and evaluated: (1) water management for reducing bioavailability of soil Cd to rice plants, (2) covering and/or replacement of contaminated soil with nonpolluted soil, (3) phytoextraction of the polluted soil by rice and other potentially promising crops, and (4) chemical remediation of Cd-contaminated soil by soil washing with chemicals.