摘要
目的 为了估算出天然辐射源致阳江高本底辐射地区居民的平均年有效剂量和某些人体组织或器官的吸收剂量。为更有效地分析剂量与效应的关系提供剂量依据 ,将调查地区居民进行了剂量分组。方法 对阳江天然高本底辐射地区 (HBRA)和相邻的正常本底对照地区 (CA)的环境γ外照射辐射水平以及部分人员的个人累积剂量进行了测量。测量了空气中氡、及其衰变子体浓度 ,计算出调查地区的氡平衡因子F和平衡当量浓度。与此同时 ,分析了调查地区饮水和食物中某些天然放射性核素的含量 ,健康人呼出气中氡、浓度的测量 ,人牙中镭和尸体及某些脏器中的2 2 6 Ra、2 2 8Ra的含量分析。结果 根据环境γ外照射辐射水平估算的人员以村为平均有效剂量HBRA和CA分别是 (2 12± 0 2 9)mSva- 1 和 (0 69± 0 0 9)mSva- 1 。HBRA的外照射本底增高主要是地球γ射线所做的贡献。HBRA和CA居民由于吸入氡、及其衰变子体所致的平均有效剂量分别是 3 2 8mSva- 1 和 1 0 3mSva- 1 ,它们致HBRA的居民支气管上皮组织和肺的吸收剂量分别为 5 40mGya- 1 和 1 0 8mGya- 1 ,约是CA的 4倍。2 2 6 Ra和2 2 8Ra致HBRA和CA居民的有效剂量分别是 2 81 88μSva- 1 和 84 5 4μSva- 1 。2 2 6 Ra和2 2 8Ra所致HBRA居民红骨髓、骨表面细?
Objective The purposes is to estimate the average annual effective dose of the inhabitants and absorbed dose in some human tissues and organs arising from natural radiation sources in the High Background Radiation Area(HBRA) of Yangjiang and in the neighboring Control Area(CA). In order to provide more effective evidence for analyzing the dose effect relationships among the cohort members in the investigated areas, we divided the local inhabitant into different dose groups. Methods We measured the environmental gamma external radiation levels and individual accumulated doses of 5?293 people in the investigated areas. The concentrations for 222 Rn, 220 Rn and their decay products in air were also surveyed. We estimated the internal doses of natural radionuclides based on the results obtained from measurements in food, in drinking water, in human teeth, in several human tissues, in human placenta, and in activity concentration of exhaled 222 Rn and 220 Rn of the residents living in the investigated areas. Results The estimation of average annual effective doses in HBRA and CA based on the data of environmental measurements of radiation level respectively are 2.12±0.29 mSv a -1 and 0.69±0.09 mSv a -1 . The sources of higher background radiation in HBRA are mainly contributed from terrestrial gamma radiation. The estimation of average annual effective doses to the residents arising from inhalation of 222 Rn, 220 Rn and their decay products was 3.28 mSv a -1 in HBRA, while that in CA was 1.03 mSv a -1 . The values of the absorbed dose of the residents in their trachea bronchial tree and lung in HBRA arising from inhalation of 222 Rn, 220 Rn and their decay products are 5.40 mGy a -1 and 1.08 mGy a -1 respectively, which are about four times of the values of the absorbed dose in CA. The estimation of average annual effective doses to the inhabitants caused by 226 Ra and 228 Ra in HBRA and CA were 281.88 μ Sv a -1 and 84.54 μ Sv a -1 respectively. The annual absorbed doses to red bone marrow and bone lining cells of the inhabitants in HBRA were estimated to be 25.54 μ Gy a -1 and 140.46 μ Gy a -1 respectively for 226 Ra and 228 Ra respectively, while in CA were estimated 7.68 μ Gy a -1 and 42.25 μ Gy a -1 respectively. Conclusion The values of the effective dose of the inhabitants arising from natural radiation sources in HBRA and CA are 5.9 mSv a -1 and 2.0 mSv a -1 respectively. The value of the effective dose of the inhabitants arising from natural radiation sources in HBRA is about three times of the value in CA. There are 23718 individuals whose effective dose is 7 mSv a -1 . The values of the effective dose caused by internal radiation and external radiation in HBRA are 3.76 mSv a -1 and 2.12 mSv a -1 respectively. The amount of the effective dose of the residents arising from inhalation of 222 Rn, 220 Rn and their decay products consists of about 88 percent of the total amount of the internal radiation dose of the residents in HBRA. The estimate of average annual effective dose the residents arising from inhalation of 222 Rn and its decay products in HBRA was 1.53 mSv a -1 . The average annual effective dose of the residents arising from 220 Rn and its decay products in HBRA is 17.5 mSv a -1 ,which is 17.5 times of the worldwide average value 0.10 mSv a -1 . Thus, the 220 Rn and its decay products are one of the main sources to cause the internal radiation dose of the inhabitants living in HBRA.
出处
《中国辐射卫生》
2004年第1期1-7,共7页
Chinese Journal of Radiological Health
基金
中国高本底辐射研究组与日本体质研究会协作项目
