No abstract

No abstract

Radioactive isotopes originating from the damaged Fukushima nuclear reactor in Japan following the earthquake and tsunami in March 2011 were found in resident marine animals and in migratory Pacific bluefin tuna (PBFT). Publication of this information resulted in a worldwide response that caused public anxiety and concern, although PBFT captured off California in August 2011 contained activity concentrations below those from naturally occurring radionuclides. To link the radioactivity to possible health impairments, we calculated doses, attributable to the Fukushima-derived and the naturally occurring radionuclides, to both the marine biota and human fish consumers. We showed that doses in all cases were dominated by the naturally occurring alpha-emitter (210)Po and that Fukushima-derived doses were three to four orders of magnitude below (210)Po-derived doses. Doses to marine biota were about two orders of magnitude below the lowest benchmark protection level proposed for ecosystems (10 µGy⋅h(-1)). The additional dose from Fukushima radionuclides to humans consuming tainted PBFT in the United States was calculated to be 0.9 and 4.7 µSv for average consumers and subsistence fishermen, respectively. Such doses are comparable to, or less than, the dose all humans routinely obtain from naturally occurring radionuclides in many food items, medical treatments, air travel, or other background sources. Although uncertainties remain regarding the assessment of cancer risk at low doses of ionizing radiation to humans, the dose received from PBFT consumption by subsistence fishermen can be estimated to result in two additional fatal cancer cases per 10,000,000 similarly exposed people.

No abstract

Several United Nations organizations sought to dispel the uncertainties and controversy that still exist concerning the effects of the Chernobyl accident. A Chernobyl Forum of international expertise was established to reach consensus on the environmental consequences and health effects attributable to radiation exposure arising from the accident. This review is a synopsis of the subgroup that examined the radiological effects to nonhuman biota within the 30-km Exclusion Zone. The response of biota to Chernobyl irradiation was a complex interaction among radiation dose, dose rate, temporal and spatial variation, varying radiation sensitivities of the different taxons, and indirect effects from other events. The radiation-induced effects to plants and animals within the 30-km Exclusion Zone around Chernobyl can be framed in three broad time periods relative to the accident: an intense exposure period during the first 30 d following the accident of 26 April 1986; a second phase that extended through the first year of exposure during which time the short-lived radionuclides decayed and longer-lived radionuclides were transported to different components of the environment by physical, chemical and biological processes; and the third and continuing long-term phase of chronic exposure with dose rates<1% of the initial values. The doses accumulated, and the observed effects on plants, soil invertebrates, terrestrial vertebrates and fish are summarized for each time period. Physiological and genetic effects on biota, as well as the indirect effects on wildlife of removing humans from the Chernobyl area, are placed in context of what was known about radioecological effects prior to the accident.