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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.
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Objective:To investigate the effect of long-term low dose ionizing radiation on the levels of interleukin (IL) and TGF-β1 in the population in high background radiation area(HBRA).Methods:Appropriate amount of peripheral blood was drawn from 41 and 44 healthy men aged 45-65 years who were randomly selected from Tangkou town of Yangjiang city (HBRA) and Hengpo town of Enping city (control area, CA), respectively. After centrifugation and stratification, the upper plasma of blood was separated to determine IL-2, sIL-2R, IL-4, IL-5 and TGF-β1 by using ELISA. The difference of plasma IL of the residents in those two regions was analyzed. The influence of region, age, smoking, drinking and income on the indexes of ILs and TGF-β1 was evaluated by Covariance analysis.Results:The concentration of IL-2 at HBRA area was slightly higher than those in the control area, but the other indexes were lower than those in CA residents. The differences of IL-5 ( t=7.124, P<0.001) and TGF-β1 ( t=4.900, P<0.001) between two areas were significant statistically. Covariance analysis showed that smoking had a significant effect on IL-2 level ( F=5.283, P<0.05). Conclusions:Under the influence of long-term low-dose ionizing radiation, all kinds of plasma interleukin levels of residents in HBRA were different with that in CA. The immune balance was biased towards Th1 type cytokines, and the immune function in HBRA was slightly stronger than that in CA, suggesting that long-term chronic low-dose ionizing radiation may induce adaptive changes in the immune function, which needs further study.