A case of repeated accidental inhalation contamination of a male subject with 137Cs

Two consecutive incidents of internal contamination occurred within a 13-mo period when a male worker (56 y, 70 kg) briefly entered and stayed (during a breakdown of control apparatus for air contamination) in a radioisotope storeroom with air contaminated by an explosion of old ampules containing Cs-137 solution. Monitoring of the first contamination began on day 34 and that of the second one within 1 h after inhalation. According to the two-exponential models long-term biological half-times of 92 and 93 d were obtained for the first and second contaminations, respectively. The short-term biological half-time for the second contamination was calculated as 3.0 d. The mean value of the fraction of Cs-137 excreted in daily urine to that in total excreta was 0.88 for the first contamination and 0.89 for the second one.