LI Xiao-juan,SUN Quan-fu.Low risk of pulmonary tuberculosis of residents in high background radiation area, Yangjiang, China[J].Chinese Journal of Radiological Medicine and Protection,2006,26(5):506-511 |
Low risk of pulmonary tuberculosis of residents in high background radiation area, Yangjiang, China |
Received:February 11, 2005 |
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KeyWords:Pulmonary tuberculosis Low dose High background radiation area |
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Abstract:: |
Objective To examine the pulmonary tuberculosis mortality risk of the residents in high background radiation area (HBRA), Yangjiang, China. Methods A cohort including 89 694 persons in HBRA and 35 385 persons in control area (CA) has been established since 1979. Person-year tables based on classified variables including sex, attained age, follow-up calendar year, and dose-rate group (high, intermediate, and low in HBRA, and control group) were tabulated using DATAB in EPICURE. Poisson regression analysis was used to estimate the relative risks (RR) of infectious and parasitic disease especially for pulmonary tuberculosis. Cumulative dose for each cohort member was obtained. Results Two million person-years were accumulated by follow-up and 612 cases of pulmonary tuberculosis ascertained. Compared with risk in the control area, statistically significant lower risk of pulmonary tuberculosis was observed in HBRA among those who aged 60 years and over; markedly decreased risk occurred among males; no significant difference was found among the 6 follow-up stages, two subregions in the HBRA, or different diagnostic facilities. A statistically significantly negative dose-response was observed (P<0.001), the higher accumulative dose, the lower dose the pulmonary tuberculosis mortality risk. Its excess relative risk (ERR/Sv) was estimated to be -1.09 (95% CI: -1.34, -0.85). No established risk factors could explain this lower risk. Conclusions The mortality of pulmonary tuberculosis among residents in HBRA who were chronically exposed to low-dose radiation was statistically significantly lower than that in the control area, and a significant dose-response relationship was observed, which probably resulted from the immunoenhancement of low dose radiation. |
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