National dose registry and trends of occupational exposure to ionising radiation in china (2009-2018)

The registry and analysis of occupational exposure is significant for radiation protection against ionising radiation. This paper presents the current status of the 'Chinese Registry of Radiation Workers (CRRW)' and trends as well as the distribution of occupational exposure to ionising radiation in China from 2009 to 2018. A database with total 6.6 million monitoring records from 820 000 workers in 85 000 radiation units for medical uses, industrial uses and miscellaneous uses is established by the CRRW. The Mann-Kendall test shows statistically significant decreasing trends of average annual effective dose for the total, medical uses and industrial uses (p < 0.01), by 0.035, 0.042 and 0.020 mSv/y, respectively. The average annual effective dose for the monitored workers is 0.403 mSv for the 10-y period. More than 96.1% of the monitored workers receive annual doses less than the limit for public exposure (1 mSv) in 2018. The annual average effective dose in medical uses is significantly higher than industrial uses and miscellaneous uses (p < 0.05/3 = 0.017). In 2018, the annual collective dose of 107.41 man.Sv is received by 378 428 monitored workers, with medical uses as the dominant contributor. These observations could be a result of improvements in radiation protection practices in China. However, it is still necessary to take rigorous and continuous surveillance and radiation protection measures, to keep individual dose as low as reasonably achievable, especially for those found to receive relatively higher doses in medical uses. (authors)