高天然放射性本底地区是研究小剂量电离辐射人群健康影响的重要场所

High background radiation area:an important source of exploring the health effects of low dose ionizing radiation.

在高天然放射性本底地区（ＨＢＲＡ）进行小剂量电离辐射对人群健康影响的研究需要分析这类研究的有利条件、薄弱环节和目前存在的问题，从而能获得有效的资料，并能有针对性地进行深入研究。方法作者选择中国的高本底辐射研究组在广东省阳江［阳东县、阳西县］内的ＨＢＲＡ和相邻的对照地区（恩平县内）所获得的流行病学资料作为一项实例进行分析。高本底辐射研究组从１９７２年起采用动态人口和定群人口观察染色体畸变率、突变性疾病发生率和癌症死亡率以及相关的剂量学和混淆因素的研究。从１９９１年开始，研究组与日本体质研究会进行合作研究。结果对环境的和宿主的诱突因素进行分类研究证明它们在高本底和对照地区是可比的；染色体畸变率在一定剂量以上时随剂量增加而增加；但ＨＢＲＡ遗传性疾病和先天性畸形总患病率不高于对照。ＨＢＲＡ的癌症死亡率与对照相比，相对危险（总的死亡率和按部位分的癌死亡率）小于１或接近１。作者引用了该研究组两种理论分析（修改的微剂量学理论和“有利与有害作用”竞争的假说）。结论在小剂量低剂量率长期作用下，照射剂量与群体的突变性疾病发生率或癌症死亡率不呈现“线性、无阈”的关系。在小剂量电离辐射作用下，人体出现有利的因素（如免疫能力增强）和?

Objective\ For obtaining more effective data from epidemiological investigation in high background radiation areas,it is necessary to analyze the advantages, disadvatages, weak points and problems of this kind of radiation research. Methods\ For epidemiological investigation of population health effects of high background radiation, the author selected high background radiation areas of Yangjiang (HBRA) and a nearby control area (CA) as an instance for analysis. The investigation included classification of dose groups, comparison of the confounding factors in the incidence of mutation related diseases, cancer mortalities and the frequencies of chromosomal aberrations between HBRA and CA. This research program has become a China Japan cooperative research since 1991. Results\ The confounding factors above mentioned were comparable between HBRA and CA, and within the dose groups in HBRA, based on a systematic study for many years. The frequencies of chromosomal aberrations increased with the increase of cumulative dose, but not for children around or below 10 years of age. The relative risks (RR) of total and site specific cancer mortalities for HBRA were lower or around 1.00, compared with CA. The incidence of hereditary diseases and congenital deformities in HBRA were in normal range. The results were interpreted preliminarily by the modified “dual radiation action” theory and the “benefit detriment competition” hypothesis. Conclusions\ The author emphasizes the necessity for continuing epidemiological research in HBRA, especially for international cooperation. He also emphasizes the importance of combination of epidemiology and radiobiology.