Estimation of the occupational exposure dose for medical diagnostic X-ray workers in Jiangsu, China, using a retrospective dosimetry method.

Medical diagnostic X-ray workers are one occupational group that has exposure to continuous low doses of external radiation over their working lifetimes. Current ICRP recommendations [ICRP. Recommendations of the International Commission on Radiological Protection. ICRP Publication 60. Ann ICRP 1991;21 (1-3)] state that there is no threshold of stochastic effects induced by radiation exposure such as carcinogenicity or genetic defects, and that the frequency of the effects is proportional to the amount of exposure to low levels of radiation, which is measured by radiation dose. In order to determine the dose information for this special occupational group over their working lifetimes (focusing particularly on workers exposed before 1985, when there was no personal dose monitoring), a sampling survey of the occupational history for these workers was conducted and an occupational history database was established. Using the database and retrospective dosimetry method of Zhang et al. (A retrospective dosimetry method for occupational dose for Chinese medical diagnostic X-ray workers. Radiat Prot Dosimetry 1998;77:69-72), the annual occupational exposure dose for medical diagnostic X-ray personnel working between 1950 and 2011 was computerized. Some annual dose results estimated using the proposed method were numerically in good agreement with the monitoring results. The average of the annual dose for these medical workers peaked during the mid-1950s and then declined, reaching very low levels by the 1990s and remaining at those levels thereafter. The trend in the annual dose is similar to that reported by earlier studies by Zielinski et al. (Health outcomes of low-dose ionizing radiation exposure among medical workers: a cohort study of the Canadian national dose registry of radiation workers. Int J Occup Med Environ Health 2009;22:149-56). The dose calculated by the retrospective dosimetry method can truly indicate the degree of the workers' exposure in their medical X-ray diagnostic work.

Nested Case-control Study of Occupational Radiation Exposure and Breast and Esophagus Cancer Risk among Medical Diagnostic X Ray Workers in Jiangsu of China.

Medical diagnostic X-ray workers are one occupational group that expose to the long-term low-dose external radiation over their working lifetime, and they may under risk of different cancers. This study aims to determine the relationship between the occupational X-ray radiation exposure and cancer risk among these workers in Jiangsu, China. We conducted Nested case-control study to investigate the occupational X-ray radiation exposure and cancer risk. Data were collected through self-administered questionnaire, which includes but not limits to demographic data, personal behaviors and family history of cancer. Retrospective dose reconstruction was conducted to estimate the cumulative doses of the x-ray workers. Inferential statistics, t-test and 2 tests were used to compare the differences between each group. We used the logistic regression model to calculate the odds ratio (OR) and 95% confidence interval (CI) of cancer by adjusting the age, gender. All 34 breast cancer cases and 45 esophageal cancer cases that detected in a cohort conducted among health workers between 1950~2011 were included in this presented study, and 158 cancer-free controls were selected by frequency-matched (1:2). Our study found that the occupational radiation exposure was associated with a significantly increased cancer risk compared with the control, especially in breast cancer and esophageal cancer (adjusted OR=2.90, 95% CI: 1.19-7.04 for breast cancer; OR=4.19, 95% CI: 1.87-9.38 for esophageal cancer, and OR=3.43, 95% CI: 1.92-6.12 for total cancer, respectively). The occupational X-ray radiation exposure was associated with increasing cancer risk, which indicates that proper intervention and prevention strategies may be needed in order to bring down the occupational cancer risk.