90 Sr specific activity of teeth of abandoned cattle after the Fukushima accident - teeth as an indicator of environmental pollution.

90 Sr specific activity in the teeth of young cattle that were abandoned in Kawauchi village and Okuma town located in the former evacuation areas of the Fukushima-Daiichi Nuclear Power Plant (FNPP) accident were measured. Additionally, specific activity in contaminated surface soils sampled from the same area was measured. (1) All cattle teeth examined were contaminated with90 Sr. The specific activity, however, varied depending on the developmental stage of the teeth during the FNPP accident; teeth that had started development before the accident exhibited comparatively lower values, while teeth developed mainly after the accident showed higher values. (2) Values of90 Sr-specific activity in teeth formed after the FNPP accident were higher than those of the bulk soil but similar to those in the exchangeable fraction (water and CH3 COONH4 soluble fractions) of the soil. The findings suggest that90 Sr was incorporated into the teeth during the process of development, and that90 Sr in the soluble and/or leachable fractions of the soil might migrate into teeth and contribute to the amount of90 Sr in the teeth. Thus, the concentration of90 Sr in teeth formed after the FNPP accident might reflect the extent of90 Sr pollution in the environment.