Abstract
A method of managing the risk of cadmium (Cd) intake through rice consumption was discussed. Risk was characterized by comparing the risk-based Cd reference concentration and the lifetime average oral exposure concentration of Cd (AME). AME was the arithmetic mean of a certain area (six hectares) of a paddy field for several decades. The annual variation of Cd concentration in rice is supposed to be log-normally distributed. Farmer's wives were suspected to be a high-risk subpopulation, and AME for that subpopulation was calculated. Rice that had a Cd concentration exceeding the maximum limit was eliminated because the subpopulation did not eat this rice. Thus, in case that several limits are used, AMEs can be re-calculated for rice whose Cd concentration is under the limit. Each paddy field was classified as “ <AME by no elimination of rice exceeding the maximum limit (no countermeasures needed; region 1)”, and “ <AME by elimination of exceeding the maximum limit (region 2)”. This method enables us to choose cost-effective countermeasures for each paddy field.
