September 5, 2017 — When the Fukushima power plant released large quantities of radioactive materials into nearby coastal waters following Japan’s massive 2011 earthquake and tsunami, it raised concerns as to whether eating contaminated seafood might impair human health—not just locally but across the Pacific.
A new study by an international research team shows that those concerns can now be laid to rest, at least for consumption of meat from migratory marine predators such as tuna, swordfish, and sharks.
The team focused on cesium, a silvery metal with a large number of radioactive isotopes. Two of these, 134Cs and 137Cs, form when uranium fuel breaks down in nuclear reactors. The cesium isotopes are of particular concern because they were discharged in large quantities following the disaster, exhibit relatively long half-lives (2.1 and 30 years respectively), and tend to accumulate in the muscle tissues that people like to eat.
However, the team’s sampling of tissues from predatory fishes and other large vertebrates collected across the northern Pacific between 2012 and 2015 revealed no detectable levels of 134Cs, and 137Cs concentrations that were generally consistent with background levels from aboveground nuclear testing during the 1940s and 50s. They collected the animals from waters near Japan, Hawaii, and California.