Date: 04 Mar 2004

Dietary cadmium intake in polluted and non-polluted areas in Japan in the past and in the present

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Abstract

Objective

The purpose of this data compilation is to overview past and current dietary exposure (primarily via rice) of general populations to cadmium (Cd) in environmentally polluted and non-polluted areas in Japan, and to compare the levels with counterpart levels in other areas in Asia.

Methods

A literature survey was conducted for publications on this subject, in either Japanese or international languages, since the early 1970s. Most of the studies identified employed the food-duplicate method in combination with atomic absorption spectrometry for Cd determination, although a few studies utilized other methods, such as the market basket method and dithizon-colorimetry.

Results

The highest estimate of dietary Cd intake (Cd-D), 600 μg Cd/day, was reported in the late 1960s for the local population in the Jinzu river basin, where Itai-itai disease had been endemic, and the Cd-D levels were 300 μg/day or higher in other polluted areas. Cd-D dropped to well below 100 μg/day when the polluted soil was replaced in the late 1970s and thereafter. In non-polluted areas, the Cd-D was reported to be approximately 100 μg/day in 1969, followed by a gradual decrease to approximately 40 μg/day in the late 1970s, to reach the current level of less than 30 μg/day. There is a trend of gradual reduction at the rate of 0.3 to 0.6 μg/day per year. Cd from rice accounted for 30 to 40% of the Cd-D in non-polluted areas, but a higher contribution was observed in some polluted areas. Nevertheless, the current Cd-D is still higher than the levels in other rice-dependent populations in east and south-east Asia.

Conclusion

The Cd-D levels reported for polluted areas were in excess of 300 μg Cd/day. Substantial reduction in Cd-D to the level below 100 μg/day was observed after remediation, such as replacement of polluted paddy soil. In non-polluted areas, there has been a gradual decrease in Cd-D in the past 25 years. Nevertheless, the levels in the current intake of the general population in Japan (25 to 30 μg/day, or <1/10 of the levels in polluted areas in the past) is still higher than the levels in other rice-dependent areas in Asia.