In the wake of the Fukushima Daiichi nuclear disaster of March 2011, scientists have discovered genetic mutations affecting three generations of butterflies near the nuclear plant, a finding that raises concerns that other species may also be affected by the ensuing radioactive fallout.
Researchers found that 12% of butterflies of the pale grass blue species who were exposed to the radiation while in the larval stage exhibited abnormalities such as damaged eyes, stunted wings and misshapen legs. The malformed butterflies were bred in labs far from the fallout zone, but despite the distance, 18% of offspring, that is, the second generation, exhibited similar mutations. In the third generation, the proportion was even higher—34% of offspring were likewise affected, even though in this instance of breeding the mated pair was made up of one mutated parent and one parent that was unaffected by radiation. It appears that mutations brought on by exposure to radiation, in this case, pass on and proliferate across generations.
A separate study published recently in the Journal of the American Medical Association examined cesium levels in 9498 individuals who lived close to Fukushima, and found them to have very low levels of radioactivity, averaging 1 millisievert each. Doses at that level are considered safe and do not pose a health risk.
But while medical experts and researchers deny that the Fukushima accident may lead to an elevated occurrence of leukemia or cancer in humans, as often occurs due to exposure to radiation, they emphasize the need for long-term medical examination. As the Chernobyl catastrophe showed, young people impacted by fallout may be at increased risk of developing thyroid cancer.
“There are a number of unknown factors surrounding the genetic impact of radiation. We still cannot 100 percent deny that the impact may come out in the future,” said Makoto Yamada, a medical doctor who examines Fukushima residents.
Japan continues its efforts to clean out the radiation from the affected area, which is the size of Connecticut, in the hopes that evacuated residents can safely return to their home. The task is immense, and it is still unknown whether the region affected by the nuclear disaster will ever truly be safe.
Six months after the nuclear meltdown, scientists collected 240 butterflies for a follow-up study. Physical and genetic abnormalities were noted in 52% of their offspring, which was considered a “dominantly high ratio.” Such a high incidence of malformation could be the result of consuming contaminated foodstuffs, internal and external exposure to radiation and from the atmosphere.
Researchers say that the pale grass blue butterflies are widespread in the Fukushima area as in the rest of Japan, and that their wing colour patterns are reliable markers of environmental change; this makes them well-suited to test radiation’s effects on living things.
The sickly butterflies are the first indication of genetic mutation in living organisms caused by the Fukushima Daiichi radiation, though there is as yet no evidence that similar abnormalities occur in humans—but further study may just bear this out. Joji Otaki, associate professor at the University of the Ryukyus in Okinawa, was quoted as saying, “Our findings suggest that the contaminants are causing ecological damage. We do not know its implication to humans.”
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