The educational program for radiation workers is essential for the safety of radiation facility that stands on radiation protection practice by each worker. However, there appears no distinct criterion for quantitative evaluation of the education effect on radiation safety. The effectiveness of education was assessed by the number and the frequency (number of contamination/number of users) of contamination, a major incident involving radioactive materials, based on the long-term contamination surveillance data from 1996 to 2001 in Nagasaki University Radioisotope Center. Facility staffs monitored contamination in the facility every day. In 1996 and 1997, the yearly total number and the frequency of contamination found in a molecular biology room, a most frequently-used laboratory, were 150 and 1.21, respectively. The improvement of education program, including introduction of technical procedures to avoid contamination in molecular biological experiments, pre-entry instruction for fresh workers to demonstrate radiation safety practices on site, and spreading the new concept “contamination happens by all means” through the radiation workers, markedly reduced both the number and the frequency of contamination to 33 and 0.48, respectively. This reduction seemed to be attributable for two different reasons; improvement of skills to avoid contamination, and thorough execution of monitoring and decontamination. These results suggested that contamination was a possible criterion for evaluating effectiveness of education program for radiation workers.
