Estimation of relative radiation exposure and risk to U. S. populations following the aftermaths of the Chernobyl and the Fukushima nuclear incidents: Putting in perspective the individual and combined exposures

The recent Fukushima nuclear incident has sparked concerns about radiation exposure levels associated with nuclear fallout. These heightened concerns had not been seen since the 1986 Chernobyl nuclear incident. Following the 9.0 earthquake and subsequent tsunami that swept across the Asian-Pacific Rim bringing devastating human and economic tolls to the Island of Japan, the Japanese people also had to endure exposures to radiation from the accidental and somewhat controlled necessary releases of radioactive material from the crippled Fukushima Daiichi Nuclear Power Plant. Multiple releases produced plumes of radioactive material that carried into the upper atmosphere, crossing the Pacific Ocean distributing nuclear fallout across Hawaii, Alaska and the continental U. S. This study addresses the relative radiation exposure to the U. S. populations following the Fukushima events. Additionally, this study presents findings for the individual and combined exposures ensuing from both the 1986 Chernobyl and the 2011 Fukushima nuclear incidents. Methods include the extraction of gross beta radioactivity data from the U. S. EPA RadNet database. Estimates of the mean background radiation levels were compared to mean radiation levels from RadNet data following the two nuclear incidents. Translated into biological exposures, these levels are contrasted with known quantified exposures in medical and other settings. Estimated relative risks, age-adjusted and gender-adjusted risks are presented individually and combined for the post-Fukushima and post-Chernobyl exposures to the general U. S. population. Possible confounders including proximity to operating nuclear facilities, dosimetric uncertainties, uncertainties of risk assessment, and extrapolation of low-dose risk estimates from high-dose risk estimates are accounted for. This study shows levels of radiation from the two nuclear incidents, both separately and combined, constitute a statistically significant increase in exposure to the U. S. population relative to the natural background levels pre-Fukushima and pre-Chernobyl. Public health concerns and implications are presented.