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 radio-
nuclides. 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 sim-
ilarly exposed people