Dr Daniel Madigan from Stanford University's Hopkins Marine Station suggested the contamination might have impacted Pacific bluefin tuna in the Western Pacific.
Caesium levels high
“We tested the possibility that juvenile [bluefin tuna] served as biological vectors of radionuclides between two distant ecoregions – the waters off Japan and the California Current Large Marine Ecosystem,” he said.
Madigan said they studied the tuna's white muscle tissue (where radioactive materials naturally accumulate) for the presence of radioactive caesium, as well as various naturally occurring radionuclides.
These results, when compared with samples taken from pre-Fukushima Californian fish, and from yellow fin tuna, found elevated levels of caesium forms Cs-134 and Cs-137.
“In contrast, the bluefin tuna caught in 2008 and yellowfin tuna caught in 2011 had no measurable Cs-134, and consistently much lower Cs-137 concentrations,” the study said.
Australia and New Zealand safe, says FSANZ
A spokesperson for Food Standards Australia and New Zealand (FSANZ) told FoodNavigator that it is working with other agencies to monitor foodstuffs from the affected prefectures in Japan.
He said the body collaborates with the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) to monitor food products for radioactive contamination.
“FSANZ remains of the view that the risk of Australian consumers being exposed to radionuclides in food imported from Japan is negligible,” he stated.
According to him, FSANZ standards for caesium levels dictate that if the combined levels of Cs-134, Cs-137 in a particular food are below becquerel (Bq) levels of 1000 Bq/kg, the food is considered safe.
Precautions in place
As a precautionary measure, the Department of Agriculture, Fisheries and Forestry Imported Food Program is monitoring foods including seafood for radionuclides from certain prefectures in Japan.
He said foods tested for Cs-134 and Cs-137 include fresh, dried and frozen fruit and vegetables, rice, cereals, seafood, seaweed and tea from specified prefectures which are in close proximity to the site of the accident.
“In addition, Japanese authorities have provisional regulatory limits, monitoring arrangements and restrictions in place on the distribution of potentially implicated foods,” he added.
A recent study in the Proceedings of the National Academy of Sciences in the US claimed radioactive material from the Fukushima nuclear accident is being transported across the Pacific Ocean by migratory fish.
