Objective To investigate the effects of low dose radiation on the level of oxidative damage and antioxidant in population of high background radiation area of Guangdong.Methods A total of 48 male residents who lived in high background radiation area(HBRA) of Guangdong province and 48 male residents who lived in neighboring Enping control area were chosen as the objectives and control respectively.The peripheral venous blood of two groups was collected,and then the levels of 8-OHdG and TrxR were determined by enzyme linked immunosorbent assay (ELISA).Results Compared with the CA group [(315.39 ± 100.59) ng/ml],the level of 8-OHdG [(272.64 ± 96.85) ng/ml] decreased significantly in HBRA (t =2.121,P ＜0.05).Compared with the CA group [(0.467 ±0.056) ng/ml],the level of TrxR [(0.496 ± 0.044) ng/ml] increased significantly in HBRA (t =-2.823,P ＜ 0.05).The results of multiple linear regression analysis demonstrated that the chronic exposure to low dose of radiation had significant effects on the expression level of 8-OHdG and TrxR (t =-2.327,2.367,P ＜ 0.05) after adjustment for confounding factors such as age,drinking,tea drinking,smoking,medical exposure and stressful events.Conclusions Chronic exposure to low dose radiation may decrease the level of oxidative and enhance the level of antioxidant.

The incidence of occupational injury accidents in the metallurgy and mechanical manufacturing industries remains high, posing risks not only to the safety and health of workers but also causing heavy economic burdens to enterprises and families. The occupational injury accidents in metallurgy and mechanical manufacturing industries were caused by the following six items： human factors, machine factors, building factors, raw material factors, environmental factors, and management factors. The types and body parts of occupational injury accidents varied among different industries due to the nature of the occupation and working environment. Occupational injury accidents were both sudden and preventable. Currently, comprehensive intervention measures for occupational injury accidents at China and abroad included safety education, improving work environments, optimizing building layout and facilities, and enhancing safety management capabilities. Effective and feasible intervention measures for occupational injury accidents should be based on the characteristics and causes of occupational injury accidents in each industry, and should include corresponding interventions for workers, machines, buildings, raw materials, environment, and management.

Respiratory protective equipment (RPE) is an effective measure to protect the health of workers. The domestic and foreign facial classfication of fit testing of RPE is mainly categorized into Los Alamos National Laboratory (LANL) classification, National Institute for Occupational Safety and Health (NIOSH) classification, principal component analysis (PCA) classification, Chinese Han adult facial classification, and Chinese young male facial classification. The LANL classification has low applicability. The NIOSH classification included different ethnicity and region of the study subjects, which is more representative for the American population. The PCA facial classification is complex to use and has low matching with RPE sizes. The Chinese Han adult facial classification and Chinese young male facial classification included more facial data of Chinese Han population and young population. There are qualitative and quantitative fit testing. Qualitative methods include the isoamyl acetate method, saccharin solution aerosol method, aerosol bitter testing solution method, and irritant smoke method which are cost-effective and easy to use, but are highly subjective to the study subjects. Quantitative methods include the aerosol generated method, environmental aerosol condensation nucleus counting method, and the controlled negative pressure method, which accurately quantify the facial fit of RPE but require specific testing equipment and high costs. It is necessary to include occupational populations from multiple industries, combine facial fit testing and fit testing methods of RPE, and establish a follow-up database based on digital information platforms, to achieve dynamic monitoring of respiratory protection levels among different occupational populations in the future.

OBJECTIVE: To investigate the current status and influencing factors of occupational stress in female workers of labor-intensive enterprises. METHODS: Totally 910 female workers from 5 labor-intensive enterprises in Guangdong Province was selected as the research subjects by random cluster sampling method. A questionnaire survey on occupational stress was conducted using the Occupational Stress Inventory-Revised Edition. RESULTS: Among the 910 female workers,14. 9%( 136/910) showed medium or higher scale on occupational role level,20. 1%( 183/910) showed medium or higher scale on occupational stress level,and 21. 4%( 195/910) showed medium or higher scale on personal resources lack. Multivariate logistic regression analysis indicated that the risk of occupational stress was high in single female workers and/or those exposed to occupational hazards( P < 0. 01). The higher the occupational role level,the higher risk of occupational stress( P < 0. 01). The less personal resources,the higher risk of occupational stress( P < 0. 01).CONCLUSION: Some female workers in labor-intensive enterprises showed medium or higher occupational stress level. The main influencing factors of occupational stress are marital status,exposure to occupational hazards,occupational role and personal resources.

Objective To analyze and set up the effective dose of different ionizing radiation for tunnel construction workers. Methods A total of five tunnels constructed using drilling and blasting methods were selected as the research subjects using the convenient sampling method. The workplace γ radiation effective dose, radon concentrations, and radioactive activity concentrations were detected, and on-site surveys were conducted to estimate the internal and external irradiation doses and total effective doses for workers in different work sites. Results Radiological hazards in tunnels constructed using drilling and blasting methods included radon and its progeny, γ radiation, radioactive dust (uranium-238, radium-226, thorium-232, and potassium-40) and others. The average total effective dose of ionizing radiation exposure for tunnel construction workers was (6.730 1±1.541 1) mSv. The average dose of radon and its progeny was (6.163 0±1.512 8) mSv, radioactive dust was (0.014 6±0.009 1) mSv, γ radiation was (0.552 6±0.138 7) mSv. The dose of radioactive dust of radon and its progeny was 0.24%. Radon and its progeny contributed more to the radioactive dose than radioactive dust and γ radiation (all P<0.05). Among all the radioactive dusts, the dose contribution ranked from highest to lowest was thorium-232, uranium-238, and radium-226. Conclusion For tunnel construction workers, the largest contribution to the effective dose of ionizing radiation exposure is from radon and its progeny for internal irradiation, followed by γ radiation for external irradiation. The contribution of radioactive dust to internal irradiation dose can be considered negligible.

Noise is a common occupational hazard in workplaces. Long-term exposure to high-intensity noise mainly causes occupational noise-induced hearing loss (ONIHL). The development of ONIHL is irreversible, and there is currently no cure. At present, risk assessment methods based on noise exposure intensities mainly include risk index assessment method, Engineering Professional Council assessment method in United Kingdom (EDC assessment method in UK), National Institute of Occupational Safety and Health assessment method in United State (NIOSH assessment method in US), and International Standardization Organization assessment method (ISO assessment method). However, the risk index assessment method is subjective and does not consider the effectiveness of workers wearing protective equipment. The EDC assessment method in UK defines ONIHL differently from China. The NIOSH assessment method in US and ISO assessment methods have population data sources that deviate from China, which can lead to bias in risk assessment. In the future, it is necessary to further carry out application research on the risk assessment of ONIHL in Chinese noise-exposed workers, compare the applicabilities of various assessment methods, conduct large-sample population epidemiological studies for verification, and fully utilize the risk-prediction function to prevent and control ONIHL.

ObjectiveTo explore the protective effect of hearing protectors worn by noise-exposed workers and its influencing factors. Methods A total of 329 occupational noise-exposed workers were selected as the research subjects by judgment sampling method. A questionnaire survey on the use of ear protectors and individual suitability tests was conducted. Intervention was carried out for those whose personal attenuation rating (PAR) did not pass the baseline standard. Results The median (M) and the 25th and 75th percentiles of baseline PAR were 17.0 (5.0, 22.5) dB. The baseline PAR of the workers who were male, aged 25-<35 years, with a working experience of 5-<15 years, with a college degree or above, wearing ear protectors for 5-<15 years, knowing the right way to wear ear protectors, and workers who wore ear protectors correctly during work was relatively high (all P<0.01). The unqualified rate of baseline PAR of the study subjects was 32.8%. The unqualified rate of baseline PAR of workers in automobile manufacturing enterprises was lower than that of workers in plastic enterprises and textile enterprises (9.2% vs 43.6%, and 9.2% vs 50.0%, both P<0.01). The M of the 108 unqualified worker on baseline PAR was improved after intervention (22.0 vs 1.0 dB, P<0.01). The rates of knowing the right way to wear ear protectors, wearing ear protectors correctly during work, and receiving training on wearing ear protectors correctly for the research subjects were 88.1%, 84.8%, and 86.6%, respectively. Workers in automobile manufacturing enterprises and plastic enterprises had higher rates of knowing the right way to wear ear protectors, wearing ear protectors correctly during work, and receiving training on wearing ear protectors correctly than those in textile enterprises (all P<0.01). Conclusion Gender, age, working experience, education level, duration of wearing ear protectors, knowledge and use of ear protectors correctly are influencing factors of the protective effect of ear protectors for noise-exposed workers.

Objective To simulate and analyze the dose distribution from external exposure and its influencing factors of induced radioactivity in proton therapy site. Methods Referencing a domestically under-construction proton therapy facility, a geometric model of the proton therapy site was constructed, and the FLUKA program was used to simulate the distribution of the induced radioactive dose of the proton therapy site under the conditions of different energies, beam angles, irradiation time, cooling time and medium of the treatment site. Results For a 230 MeV proton beam with a current of 3.0 nA, directed along the negative Z-axis and irradiating a phantom for two minutes, at the shutdown moment, the ambient dose equivalent rates in air and vacuum 5, 30, and 50 cm away from the phantom surface were (1 039.02±5.82)-(127.86±1.20) and (1 037.96±4.38)~(127.35±0.93) μSv/h, respectively. The mean difference was 0.51~1.06 μSv/h, and the air-immersed external irradiation accounted for <1% of the total irradiation, which rapidly decreased to 1/15 of the shutdown moment value after cooling for 10 minutes. Under the condition of 130~250 MeV, the ambient dose equivalent rates at the shutdown moments 5, 30 and 50 cm away from the surface of the phantom were (427.49±3.12)-(1 058.41±4.66), (100.36±0.92)-(259.70±1.69) and (50.15±0.68)-(131.93±1.11) μSv/h, respectively. Irradiation for one-five minutes, and at the moment of shutdown at 5, 30, and 50 cm from the surface of the phantom were (688.19±3.33)-(1 594.04±8.08), (167.60±1.35)-(388.24±2.96) and (84.73±0.69)-(195.94±1.56) μSv/h. The peripheral dose-equivalent rate of the sensed radioactivity decreases with the irradiation time, the energy of the beam, and the distance from the model. The peak dose equivalent rate around the induced radioactivity exists in the beam direction, which is significantly larger than that in the non-beam direction. Conclusion Proton therapy sites are characterized by relatively large levels of induced peripheral radioactive dose equivalent rates, mainly originating from patients. In actual practice, a suitable working position can be chosen according to the direction of the beam current, especially the direction of the final irradiation field beam current, in the non-beam current direction and as far away from the patient as possible. Within 10 minutes after the end of treatment, staff should try to avoid close contact with the patients.

Objective:To explore the applicability of different exposure assessment methods in occupational health risk assessment of trichloroethylene (TCE) occupation posts in electroplating enterprise.Methods:In November 2018, the occupational health risk assessments are conducted in trichloroethylene (TCE) occupation posts of 6 metal plating enterprises in a street in Shenzhen by using the qualitative risk assessment, semi-quantitative risk assessment (including contact ratio method, contact index method and synthesis index method) and quantitative risk assessment method (including non-carcinogenic and carcinogenic risk assessment methods) , and the results of different methods are compared.Results:The results of qualitative assessment method are all level 4 (high risk) ; the results of contact ratio method show that the risk level is level 5 (very high risk) ; the results of contact index method and Synthesis index method show that the risk level is level 3 and level 4, 66.7% and 33.3% respectively; Non-carcinogenic risk assessment results show that TCE jobs are "unacceptable"; carcinogenic risk assessment results in carcinogenic inhalation excess risk of 50% each being "unacceptable" and "acceptable". The results of the six risk assessment methods showed that there were 3 "substantially consistent", 1 "partially consistent", and 2 "inconsistent" among the 6 companies.Conclusion:Synthesis index method and the carcinogenic risk assessment method are more suitable for occupational health risks of TCE occupation posts.

Objective:To explore the applicability of different exposure assessment methods in occupational health risk assessment of trichloroethylene (TCE) occupation posts in electroplating enterprise.Methods:In November 2018, the occupational health risk assessments are conducted in trichloroethylene (TCE) occupation posts of 6 metal plating enterprises in a street in Shenzhen by using the qualitative risk assessment, semi-quantitative risk assessment (including contact ratio method, contact index method and synthesis index method) and quantitative risk assessment method (including non-carcinogenic and carcinogenic risk assessment methods) , and the results of different methods are compared.Results:The results of qualitative assessment method are all level 4 (high risk) ; the results of contact ratio method show that the risk level is level 5 (very high risk) ; the results of contact index method and Synthesis index method show that the risk level is level 3 and level 4, 66.7% and 33.3% respectively; Non-carcinogenic risk assessment results show that TCE jobs are "unacceptable"; carcinogenic risk assessment results in carcinogenic inhalation excess risk of 50% each being "unacceptable" and "acceptable". The results of the six risk assessment methods showed that there were 3 "substantially consistent", 1 "partially consistent", and 2 "inconsistent" among the 6 companies.Conclusion:Synthesis index method and the carcinogenic risk assessment method are more suitable for occupational health risks of TCE occupation posts.