"Some parts of the Earth's surface have high natural radiation background, but no harmful health effects have ever been detected in these areas. This is consistent with other studies of the incidence of cancers in populations exposed to radiation from anthropogenic sources. In the United States and in China, for example, the incidence of cancers was found to be lower in regions with high natural radiation than in regions with low natural radiation (Frigerio et al. 1973; Frigerio and Stowe 1976; Wei et al 1990). Among British radiologists exposed mainly to x-rays, the mortality from all causes including cancer is lower by about 50% than that in the average male population of England and Wales (Berrington et al. 2001). Also, in other population groups exposed to low doses of ionizing radiation, a lower percentage of malignant tumours has been observed [e.g. patients dosed with I-131 and X-rays, dial painters, chemists, persons exposed to higher levels of indoor radon, and A-bomb survivors] (Cohen 2000; Luckey 2003; UNSCEAR 1994)."Online at http://www.world-nuclear.org/uploadedFiles/org/info/Safety_and_Security/Safety_of_Plants/jaworowski_chernobyl.pdf
Lydia P. Zablotska wrote an article entitled 30 Years After the Chernobyl Accident: Time for Reflection and Re-Evaluation of Current Disaster Prepardness Plans, which appeared in Journal of Urban Health: Bulletin of the New York Academy of Medicine 93, 3 (2016).
"Mental health effects were the most significant public health consequence of the accident in the three most contaminated countries.... Inhabitants of contaminated areas ... received low radiation doses equivalent to approximately one whole-body computed tomography (CT) scan.... Those living further away ... [received] radiation exposure doses comparable to one annual background radiation dose."