Fukushima Nuclear Accident Produces Mutant Butterflies

A new study finds dented eyes, undeveloped legs and malformed antennae in pale grass blue butterflies.

Pale grass blue butterflies

Pale grass blue (Zizeeria maha) butterflies are widespread in Japan, and often studied as indicators of environmental change. (Photo: Toshiaki Ono/a.collectionRF via Getty Images)

Kelly Zhou has written on a variety of topics for TakePart, predominantly politics, education, and wildlife.

Radiation from the Fukushima Daiichi nuclear accident likely caused mutations in pale grass blue butterflies in Japan, a recent Scientific Reports study announced.

After the March 2011 nuclear power plant disaster in Fukushima, Japan, the release of radiation became a cause for concern. In this study, scientists collected adult pale grass blue butterflies two months after the nuclear power plant disaster in Japan, and found that 12 percent had deformations in their eyes, wings and palpi, including color pattern changes and dented eyes.

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“The accident caused physiological and genetic damage to the pale grass blue Zizeeria maha, a common lycaenid butterfly in Japan,” the paper states.

The researchers gathered 144 butterflies from Fukushima and nine surrounding areas in May 2011. At the time of the March accident, these adult butterflies would have been overwintering, or waiting out the season, as larvae. The larvae would have been exposed to not only external artificial radiation but also internal radiation from ingested food, according to the study.

The pale grass blue butterfly is a useful indicator to evaluate environmental conditions in Japan, particularly because it is widespread and its wing color patterns are sensitive to environmental changes, the paper explained.

When scientists studied the offspring of these adult butterflies, they found that the abnormality rate increased to 18 percent, including undeveloped legs, dented eyes and rumpled wings. Even more concerning, when the offspring mated with healthy butterflies not affected by Fukushima, the mutation rate rose to 34 percent. 

The scientists also collected 238 more butterflies in September 2011 from the same locations, and found that the rate of abnormalities was double that in the first collection of butterflies in May. Antennae, legs and wing color patterns were all noticeably affected in this round of subjects.

The scientists also tested unaffected butterflies with artificial radiation in the lab, producing similar negative effects.

“All of these results suggest that radiation caused adverse effects at the physiological and genetic levels,” according to the study.

The paper mentions that Fukushima radiation raises “serious concerns about biological influences on living organisms”, which could potentially destroy ecosystems or cause chronic disease.

But the possible threat to humans is said to be low, reported the Wall Street Journal earlier this year. A panel of U.S. radiation experts who studied the Fukushima case expected the impact to be minor, and that it would not measurably raise the risk of getting cancer.

Do you think humans should be concerned? Let us know in the comments.

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