Consideration on the Necessity of Tritium Limit in Foods in Japan — Perspective on the Current Food Regulation

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The current radioactive cesium limit in food in Japan was established on the basis of a permissible dose relating to the food regulation in Japan (1 mSvy⁻¹) on April 2012. The current limit only accounts for the influence of ¹³⁴Cs, ¹³⁷Cs, ⁹⁰Sr, ²³⁸Pu, ²³⁹Pu, ²⁴⁰Pu, ²⁴¹Pu, and ¹⁰⁶Ru; however, the contribution due to other radionuclides such as ³H is not included. In this study, the principle focus was the influence of ³H and the necessity for establishing permissible ³H food contamination limits in the light of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. It was found that no adjustment to ³H limits in food was required due the FDNPP accident. This is because effective doses that include the contributions of ³H would not exceed the permissible dose for food regulation in Japan as long as regulatory controls are performed using the current limits. The results and concepts in this study will prove helpful for food regulation when fusion reactors with ³H are operational.