Characteristics of radioactive contamination of vegetables derived from the Fukushima nuclear accident

Abstract

We examined the characteristics of the radioactive contamination and the physical removal of radioactivity from contaminated cabbage and spinach. In a distribution imaging study, there were two types of contamination, spot type and spread type, of cabbage and spinach. The relative radioactivity (PSL) of the face of the leaf was much higher than that of the back of a leaf of cabbage. The ratio of relative radioactivity (PSL) between spot contami- nation and spread contamination in a leaf of spinach was 9.4% and 90.6%, respectively. More than 80% of radio- activity attaches to the surface of leaves of spinach. There was no significant difference of radioactivity removal between hand-washing and rinsing with running water. The degree of removal of radioactivity from contaminated spinach depended on the length of time between contamination and rinsing. When contaminated spinach was rinsed within 1 week after contamination, the removal ratio of 131I and 137Cs was high, with 50% and 70%, respec- tively. When rinsing contaminated spinaches more than 2 weeks after contamination, the removal ratio of 131I and 137Cs was low, approximately 34% and 69%, respectively.