Background Excessive radon exposure is considered the second risk factor for lung cancer. Since the opening of the subway in a city of Zhejiang Province, the exposure level of radioactive gas radon in subway stations and its impact on occupational health have become one of the important issues of public concern. Objective To monitor the radon concentration of subways in a city in Zhejiang Province and explore the effect of radon exposure on chromosome aberration and micronuclei in the working population. Methods A total of 55 vehicle control rooms of 55 stations affiliated to two different subway lines in a city were measured for one year; the 110 ticket offices and 55 security checkpoints from the same 55 stations were measured from 16 March to 14 June. The radon concentrations were compared by job types, subway lines, and seasons referring to Measurement methods for determination of radon in environmental air (HJ 1212-2021). Peripheral blood lymphocyte chromosome aberration and micronucleus analyses were conducted in 165 subway workers from monitoring sites for three different job types, then the influencing factors were analyzed. The detection methods were adopted from the standards of Test and assessment of chromosomal aberrations on occupational health examinations for radiation workers (GBZ/T 248-2014) and Standard for the method of micronucleus detection in lymphocytes on occupational health examination for radiation workers and exposure dose estimation (GBZ/T 328-2023). Results The radon concentration range of the target subways in Zhejiang Province was 10-320 Bq·m⁻³, all lower than the national limit (≤400 Bq·m⁻³). The differences in radon radioactivity levels among different lines, job types, and time segments were statistically significant (P<0.05). The rates of chromosomal aberration and micronucleus formation among the 165 subjects were 0.224% and 0.024%, respectively. There were significant differences in the rates of chromosome aberration and micronuclei among different jobs (vehicle control room, ticket office, security checkpoint) (P<0.05), but the abnormal rates were lower than the limits of the corresponding national standard. No significant correlation was found between jobs and chromosomal aberrations or micronuclei (P>0.05). Chromosome aberration and micronuclei varied by age, subway station seniority, and smoking (P<0.05). No effect of the above factors on chromosome aberration and micronuclei was observed by logistic regression (P>0.05). Conclusion The radon concentration in the target subway system is at a normal level. The rates of chromosomal aberration and micronucleus formation vary by jobs, but both are lower than the corresponding national limits. Therefore, radon exposure has not yet caused outstanding health impact on the subway workers.

Objective To investigate the current situation of occupational health of radiation workers in Zhejiang Province, China, and to provide a theoretical basis for the improvement of standards and management systems for occupational health examinations of radiation workers. Methods Data of occupational health examination cases were collected from occupational health examination institutions, including basic information, type of physical examination (pre-job, on-job, off-job), and health examination results. The differences in occupational health examination results among different groups were analyzed, and the factors influencing occupational health of radiation workers were analyzed using a logistic regression model. Results A total of 5668 cases were collected, with 86% of the participants being male and 14% being female. Compared with the pre-job group, the on-job group showed an increased abnormal rate of triiodothyronine and the off-job group demonstrated an increased abnormal rate of leukocyte count (P < 0.05). Compared with the industrial group, the nuclear fuel group showed decreased abnormal rates of thyroid structure and thyroxine and an increased abnormal rate of triiodothyronine, and the medical group demonstrated an increased abnormal rate of thyroid structure (P < 0.05). The abnormal rates of thyroid structure and white blood cell count increased with the increase of working age (P < 0.05). The abnormal rates of white blood cell count, thyroid structure, triiodothyronine, and thyroid stimulating hormone were higher in female radiation workers than in male radiation workers (P < 0.05). Sex (female), radiation work history, and age were the risk factors affecting the occupational health of radiation workers (P < 0.05). Conclusion The occupational health status of radiological workers in Zhejiang Province needs to be further improved, and the occupational health management of radiological workers should be strengthened.

Objective To investigate the current situation of occupational health of radiation workers in Zhejiang Province, China, and to provide a theoretical basis for the improvement of standards and management systems for occupational health examinations of radiation workers. Methods Data of occupational health examination cases were collected from occupational health examination institutions, including basic information, type of physical examination (pre-job, on-job, off-job), and health examination results. The differences in occupational health examination results among different groups were analyzed, and the factors influencing occupational health of radiation workers were analyzed using a logistic regression model. Results A total of 5668 cases were collected, with 86% of the participants being male and 14% being female. Compared with the pre-job group, the on-job group showed an increased abnormal rate of triiodothyronine and the off-job group demonstrated an increased abnormal rate of leukocyte count (P < 0.05). Compared with the industrial group, the nuclear fuel group showed decreased abnormal rates of thyroid structure and thyroxine and an increased abnormal rate of triiodothyronine, and the medical group demonstrated an increased abnormal rate of thyroid structure (P < 0.05). The abnormal rates of thyroid structure and white blood cell count increased with the increase of working age (P < 0.05). The abnormal rates of white blood cell count, thyroid structure, triiodothyronine, and thyroid stimulating hormone were higher in female radiation workers than in male radiation workers (P < 0.05). Sex (female), radiation work history, and age were the risk factors affecting the occupational health of radiation workers (P < 0.05). Conclusion The occupational health status of radiological workers in Zhejiang Province needs to be further improved, and the occupational health management of radiological workers should be strengthened.

Objective:To improve the dosimetric accuracy of cell irradiation experiments by developing a method of accurately measuring the absorbed dose of ultra-thin solution in culture dishes under 200 kV medium-energy X-rays using EBT3 films.Methods:EBT3 film dose calibration was performed under Cyberknife 6 MV beam, and the beam quality (half-value layer) and effective energy of the 200 kV beam used in this study generated from Small Animal Radiation Research Platform through measurements and calculations were obtained to determine the EBT3 energy response correction factor. The 200 kV beam was utilized to irradiate three commonly used culture dishes filled with ultra-thin liquid placed on EBT3 films and the corrected EBT3 doses were taken as the liquid absorbed doses. The dose linearity of immersed films was also measured and analyzed. In addition, after modeling the irradiation environment, the independent Monte Carlo calculations of the liquid absorbed dose were performed by MCNP5 program. The calculation results were compared with the film measurement results to verify the accuracy of the measured doses.Results:The 200 kV beam had a half-value layer of 8.77 mm aluminum and effective energy of 57.4 keV, corresponding to an energy response correction factor of 0.889. The average liquid absorbed doses of large, medium and small culture dishes measured by EBT3 films under the specified parameters of 200 kV beam were (1.434±0.004) Gy, (1.467±0.011) Gy and (1.469±0.027) Gy after correction, respectively. The percentage errors from the corresponding Monte Carlo calculation doses were 0.07%, -0.70%, and 0.47%, respectively, where the relatively consistent results could be found. In addition, the dose linearity of immersed EBT3 films was also good, with coefficient of determination R2=0.9972. Conclusion:The method of measuring the dose of ultra-thin cell solution using EBT3 films proposed in this study is feasible, and the dose results obtained yield high accuracy under 200 kV beam.

Objective To investigate the operation status and service level of radiation occupational health inspection institutions in Zhejiang Province, China, and to provide a basis for administrative departments and quality management departments to develop policies. Methods The investigation data of radiation occupational health inspection institutions in Zhejiang Province were collected for descriptive analysis of the regional distribution, nature, and service qualification of the institutions. Results There were 27 radiation occupational health inspection institutions in Zhejiang Province. These institutions were located in 11 cities, of which 85.18% were public institutions and 14.72% were private institutions. For the physical examination workload of radiation workers in Zhejiang Province in 2021, general hospitals accounted for 75.90%, private institutions accounted for 4.51%, and occupational prevention and treatment hospitals accounted for 19.59%. In the radiation occupational health inspection institutions, the stand-alone and online software installation rates were 33.33% and 37.04%, respectively. A total of 26 986 individuals (82.97%) underwent chromosome aberration examination. The examination rates of thyroid color Doppler ultrasound examination and eye lens examination were 41.24% and 82.97%, respectively. Pre-job, on-job, and off-job physical examination accounted for 25.81%, 70.52%, and 3.67%, respectively. For radiation workers who underwent on-job physical examination, diagnostic radiology workers accounted for the highest proportion of 34.90%. The excellent, qualified, and unqualified rates of 27 radiation occupational health inspection institutions were 7.41%, 88.89%, and 3.70%, respectively. Conclusion The network of radiation occupational health inspection institutions in Zhejiang Province is well-established and located mainly in general hospitals, occupational prevention and control institutions, and private institutions. To enhance the quality and proficiency of occupational health examinations, it is imperative to prioritize self-improvement and management, reinforce law enforcement supervision, actively engage in blind sample assessments, and advance the application of information technology and standardized services.

Objective:To investigate the activity concentrations of 90Sr and 137Cs in water in Hangzhou urban area. Methods:From 2012 to 2020, Qiantang River water as an important drinking water source, tap water as direct drinking water for residents, and West Lake water in tourists crowded area were selected forwater quality monitoring with respect to conctnts of 90Sr and 137Cs. The activity concentrations of 90Sr and 137Cs in water samples, as collected in wet and dry seasons resepectively, were determined by radiochemical analysis, with the 137Cs to 90Sr activity ratios obtained. Results:From 2012 to 2020, the activity concentrations of 90Sr and 137Cs in tap water were (2.0±1.1) - (7.4±0.4) mBq/L and (0.45±0.06) - (7.1±0.6) mBq/L, respectively. The 137Cs to 90Sr activity ratios ranged from 0.07 to 2.40. The activity concentrations of 90Sr and 137Cs in Qiantang River were (3.7±1.1) - (17.0±4.4) mBq/L and (0.28±0.01) - (15.0±4.5) mBq/L, respectively. The 137Cs to 90Sr activity ratios ranged from 0.03 to 0.90. The activity concentrations of 90Sr and 137Cs in West Lake water were (2.2±0.5) - (11.0±2.0) mBq/L and (0.32±0.04) - (7.9±1.9) mBq/L, respectively. The 137Cs to 90Sr activity ratios ranged from 0.05 to 1.20. Conclusions:The activity concentrations of 90Sr and 137Cs in water in Hangzhou urban area were at the background levels, lower than the concentration limits, 10 Bq/L both for 90Sr and 137Cs recommended by WHO in the 4 th edition of Guidelines for Drinking Water Quality.

Objective:To investigate and analyze the level of the gross radioactivity, and its variation trend, in surrounding drinking water since the second phase expansion project at Qinshan Nuclear Power Plant was officially put into operation.Methods:From 2010 to 2022, the source water, factory water and tap water within 30 km of Qinshan Nuclear Power Plant were collected in the flood season (May) and dry period (October) every year. The total α and total β radioactivity concentrations in drinking water was measured and analyzed. The levels of total radioactivity in drinking water around different nuclear power plants in China and around non-nuclear power plant areas was compared.Results:The mean radioactivity concentrations of total α and total β were (0.021±0.019) and (0.204±0.058) Bq/L in source water, (0.010±0.005) and (0.185±0.056) Bq/L in factory water , and (0.012±0.007) and (0.170±0.058) Bq/L in tap water, respectively, all lower than the limits stipulated in the Sanitary Standards for Drinking Water. There were no significant differences in the monitoring result of betweem the three types of water samples both in the flood and dry periods ( P> 0.05). The total radioactivity level in drinking water around Qinshan Nuclear Power Plant site was close to that in drinking water around different nuclear power plants in China and around areas without nuclear power plants. Conclusions:Following the second phase of the expansion project officially being put into operation, the total α and β radioactivity level in drinking water around the Qinshan Nuclear Power Plant has been in a stable trend and lower than the guidance level given in national standard.

Objective:To investigate the levels of gross radioactivity in drinking water in Hangzhou city before and after Qiandao Lake as the water source to the main urban area of Hangzhou.Methods:Since 2012, water samples were collected from water source, factory water and peripheral water in rainy and dry seasons, respectively, to determine their gross α and β activity concentrations for comparison and analysis.Results:The gross radioactivity levels in drinking water in Hangzhou are lower than the limits specified in the national standard "Standards for drinking water quality" (GB 5749-2006), without statistically significant difference for these water sources between the rainy and dry season ( P>0.05). The gross α(0.008±0.000)and gross β(0.034±0.013)levels in Qiandao lake were both less than those in Qiantang river ( Z=-3.235, -4.058, P<0.05), with significant difference ( Z=-2.181, -4.577, P<0.05). There was no significant difference in gross α and gross β in factory water and peripheral water before and after the operation of Qiandao Lake water supply project ( P>0.05). Conclusions:The gross radioactivity in drinking water in downtown Hangzhou are low from 2012 to 2020. The gross radioactivity levels in Qiandao Lake are lower than in the lower reaches of Qiantang river and Dongtiao steam. No impact was generated on radioactivity levels in drinking water after Qiandao lake supplied water to Hangzhou.

Objective:To investigate and analyze the radioactivity level of 90Sr in offshore seawater and seafood therein around Sanmen nuclear power plant (NPP) and to estimate the annual committed effective dose to local population from ingestion of 90Sr in seafood from 2015 to 2019. Methods:From 2015 to 2019, the offshore seawater and 3 kinds of marine products grown locally in Sanmen and consumed by local residents were collected for measurement of the level of 90Sr radioactivity. The committed effective doses to the local population were estimated based on monitoring result and consumption data on seafood in Zhejiang offshore. Results:The radioactivity concentrations of 90Sr ranged from 2.4 to 4.1 mBq/L in the seawater, close to the natural radioacrive background level and from 6.7×10 -2 to 1.3 Bq/kg in seafood, lower than the standard values specified in the "Limited concentrations of radioactive materials in foods" (GB 14882-94). Annual committed effective dose to the local population from 90Sr attributable to consumption of seafood in Sanmen County from 2015 to 2019 were 2.2×10 -4-4.2×10 -4mSv, respectively, far lower than the worldwide committed effective dose result ing from internal exposure. Conclusions:From 2015 to 2019, the radioactivity concentration of 90Sr in seawater and seafood are stable, with neglectable dose burden to the local population.

Objective:To investigate and analyze the radioactivity levels of 90Sr and 137Cs in drinking water and 137Cs in food after the installation of the first AP1000 nuclear power unit in China. Methods:From 2012 to 2019, four drinking water monitoring points around AP1000 nuclear power unit located at Sanmen nuclear power plant site were collected during the wet season and dry season, 90Sr and 137Cs and radioactivity concentrations were determined in drinking water. Local rice, cabbage, crucian and mullet were collected to determine the radioactivity concentration of 137Cs. Results:From 2012 to 2019, the radioactivity concentrations of 90Sr and 137Cs in drinking water were 1.2-9.8 mBq/L and 0.2-8.1 mBq/L, respectively. The radioactivity concentration of 137Cs in food were 1.1×10 -2-2.8×10 -1 Bq/kg, lower than the limits specified in the Limited concentrations of radioactive materials in foods (GB 14882-94). Conclusions:After the installation of the first AP1000 nuclear power unit in China, the radioactivity levels of 90Sr and 137Cs in drinking water and 137Cs in foods are stable, without environmental impact identified.