Fukushima Radiation to Reach Highest Levels By End of 2015

Radiation from the Fukushima-Daiichi power plant disaster in 2011 is still being released into the atmosphere, with potential impacts on both humans and wildlife, but a new study indicates that this fallout will reach its highest levels by the end of 2015. After that, they are expected to gradually decrease back to normal levels.

The study, published Monday in the journal Proceedings of the National Academy of Sciences (PNAS), focused mainly on radioactivity from cesium-137. This is the longest-lived of two forms of cesium released in the catastrophe, which ocean currents have carried east. Luckily, even at its peak levels of radioactivity from cesium-137 will still fall far below levels that the US and Canadian governments deem unsafe for drinking water.

In previous studies, Fukushima radiation has been shown to birds, monkeys, butterflies, and other insects in Japan. For example, Japanese macaques (Macaca fuscata) near the nuclear power plant were found to have abnormally low red and white blood cell counts, which could lead to a weaker immune system. Also pale grass glue butterflies in the area were shown to be smaller and grow slower than average, suggesting radiation is impacting their development.

After a magnitude-9 earthquake triggered a tsunami in Japan in March 2011, Fukushima lost emergency power and the plant struggled to keep reactors cool, resulting in three of the four reactors partially melting. Though containment efforts were largely a success, the range of radiocesium soil concentrations in Fukushima City were still 10,000-300,000 Bq/m² following the disaster - high enough to be deemed a temporary health threat. And this radiation leakage has continued for the last few years, with no signs of easing up until the end of 2015, according to the study.

The findings, based on data from 2011-2013 from 26 sampling sites stretching for 1,000 miles from the Juan de Fuca Strait, show that the radiation level from cesium-137 will likely reach about 3 to 5 Becquerels per cubic meter (Bq/m² ) of water at most. By contrast, Canada's drinking water standard for cesium-137 is 10,000 Bq/m².

"The conclusions haven't changed," researcher and chemical oceanographer John Smith told The Christian Science Monitor.

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