Occupational exposures and dose reduction in Japan

Occupational exposure to ionizing radiation in Japan is governed by a series of regulations. Based on ICRP Publication 26, these regulations were revised in 1989. Assessment of occupational exposure is essential to assure the status of radiation protection or workers in various occupations, to identify the possible improvements of regulations and to revise regulations as necessary. This paper presents a brief review of the categories of Japanese radiation workers, a review of occupational exposure for the year 1990, a summary of trends for the period of 1976 to 1990 and a perspective of future Japanese occupational exposure as related to ICRP Publication 60. In general the dose distribution of monitored workers has been a hybrid-lognormal distribution rather than a lognormal distribution. This reflects the strengthened higher individual dose controls. In the 1990s the number of monitored workers in Japan will increase but there is the potential to attain both a reduction of collective dose and a reduction of the number of workers exposed to more than 20 mSv. (author)