1 of 1 Sakura cherry blossoms in Fukushima Prefecture, Japan — Photo: Fukushima Travel Sakura cherry blossoms in Fukushima Prefecture, Japan — Photo: Fukushima Travel
A group of researchers in Japan has developed a rapid and relatively inexpensive method for assessing the risk of mutations caused by low doses of radiation, such as those recorded as remnants around the Fukushima power plant. The Fukushima Daiichi plant leaked radiation after an earthquake in 2011 that required the evacuation of 154,000 people from an area of 726 km2. This accident and the 1986 Chernobyl power plant collapse in Ukraine were the only ones to date to achieve the top score (seven) on the INES (International Nuclear Episode Scale) disaster scale.
The affected region was divided into three zones according to the intensity of the contamination. Since 2014, the Japanese government has suspended evacuation orders for areas it deems safe again and allowed them to be reoccupied. The most critical area, the socalled Difficult Return Zone, has been shrinking since 2017. But citizens and tourists remain concerned. “People living in the affected areas are concerned and need to feel safe in their daily lives,” said Fukushima University environmental scientist Shingo Kaneko. “We wanted to cleanse the country of misinformation about the biological consequences of the nuclear power plant accident.”
Kaneko worked on research led by biologist Saneyoshi Ueno of the Forest Products and Forest Products Management Research Institute in Tsukuba. Before the study, there were records of various conifers in the disaster region showing abnormal branches, and rumors attributed the phenomenon to mutations. The team decided to study two tree species common in the disaster area: the Japanese cedar (Cryptomeria japonica) and the Japanese cherry (Prunus serrulata), known as sakura when in bloom.
The analyzes included measuring the presence of cesium 137, seed germination and plant crossing to account for different manifestations of the genetic material. Using genetic analysis and bioinformatics tools, the scientists searched for DNMs, the acronym for “de novo” mutations that would have only appeared after the nuclear accident. The search found very little manifestation of DNMs in cedars and only in the Difficult Return Zone. No mutation that could have been caused by the nuclear accident was found in the cherry trees.
The conclusion was published in the Environmental International Journal at the end of March. Days later, on April 1, the Japanese government lifted the evacuation order for another part of the city of Tomioka. Now 93% of the city area is open for reoccupation. The area, cleared in April, is famous for a 2.2kilometer avenue of 400 cherry trees that can now be enjoyed with peace of mind by local residents and tourists alike.