Radiation leak linked to butterfly mutations

TOKYO — Radiation that leaked from the Fukushima nuclear plant following last year’s tsunami caused mutations in some butterflies, including dented eyes and stunted wings, although humans seem relatively unaffected, researchers say.

The mutations are the first evidence that the radiation has caused genetic changes in living organisms. They will probably add to concerns about potential health risks among humans, but scientists say more study is needed to link human health with the Fukushima disaster.

The catastrophic meltdowns in three reactors of Fukushima Daiichi powerplant after it was damaged by the 9.0-magnitude earthquake and tsunami on March 11, 2011, prompted a public backlash against nuclear power, and forced the government to reassess resource-scarce Japan’s entire energy strategy.

But the most visible example of the radiation’s effect was claimed by a group of Japanese researchers who found radical physical changes in successive generations of a type of butterfly they said were caused by radiation exposure. They also said that the threat to humans remains unclear.

“Our findings suggest that the contaminants are causing ecological damage. I do not know its implication to humans,” Joji Otaki of the University of the Ryukyus in Okinawa, a member of the research team, said in an email.

A separate study, made public this week, found very low levels of radioactivity in people who were living near the Fukushima plant when it suffered the meltdowns.

The research on the butterflies, published in Scientific Reports, says pale grass blue butterflies, a common species in Japan, collected near the Fukushima plant showed signs of genetic mutations, such as dented eyes, malformed legs and antennae, and stunted wings.

Experts said they viewed the research as significant.