Historical Lessons on Cadmium Environmental Pollution Problems in Japan and Current Cadmium Exposure Situation

Abstract

In 1968, the Ministry of Health and Welfare acknowledged that itai-itai disease, which occurred frequently in the Jinzu River basin of Toyama Prefecture, was a pollution disease. This chapter explores three topics related to itai-itai disease that have not been examined before with the aim of extracting historical lessons for the cadmium (Cd) environmental pollution problem in Japan. The first topic deals with the progress made by Dr. Kinichi Yoshioka, who first reported Cd environmental contamination, and suggested that itai-itai disease could be caused by chronic Cd poisoning. This topic focuses on the significance of ecological and epidemiological studies concerned with the actual circumstances surrounding heavy metal pollution (mainly Cd), in particular, the exposure route to the local residents. The second topic introduces the decision made by the administrative official that summarizes the opinion of the Ministry of Health and Welfare that “itai-itai disease is a pollution disorder caused by chronic Cd poisoning.” This opinion became the starting point for government pollution countermeasures as well as its policy decision-making process and illustrates that Cd environmental pollution presented a critical problem to regulatory science. The third topic analyzes “Cadmium Studies in Japan: A Review” published in 1978 and “Interim Report Summary” published in 1989. The progress made and the challenges encountered by the “Itai-itai Disease and Chronic Cd Poisoning Study Group” are then summarized. Since 1969, this group has been commissioned by the Ministry of Health and Welfare or the Ministry of the Environment to conduct studies to determine the relation between itai-itai disease and Cd poisoning. In the present circumstances surrounding Cd exposure in Japan, the daily Cd intake from the diet of general residents has decreased from 31.1 μg in 1981 to 17.8 μg in 2015 (a reduction of over 30% in over 30 years). The reason for this was considered to be a decrease in the intake of rice, a staple Japanese food, and a reduction in the Cd concentration in rice due to improvements in rice cultivation methods.