Mutant butterflies a result of Fukushima nuclear disaster, researchers say
In the first sign that the Fukushima nuclear disaster may
be changing life around it, scientists say they've found mutant butterflies.
Some of the butterflies had abnormalities in their legs,
antennae, and abdomens, and dents in their eyes, according to the study
published in Scientific Reports, an online journal from the team behind Nature.
Researchers also found that some affected butterflies had broken or wrinkled
wings, changes in wing size, color pattern changes, and spots disappearing or
increasing on the butterflies.
The study began two months after an earthquake and
tsunami devastated swaths of northeastern Japan in March 2011, triggering a
nuclear disaster. The Fukushima Daiichi plant spewed radiation and displaced
tens of thousands of residents from the surrounding area in the worst nuclear
accident since the 1986 Chernobyl disaster in Ukraine.
In May 2011, researchers collected more than 100 pale
grass blue butterflies in and around the Fukushima prefecture and found that
12% of them had abnormalities or mutations. When those butterflies mated, the
rate of mutations in the offspring rose to 18%, according to the study, which
added that some died before reaching adulthood. When the offspring mated with
healthy butterflies that weren't affected by the nuclear crisis, the
abnormality rate rose to 34%, indicating that the mutations were being passed
on through genes to offspring at high rates even when one of the parent
butterflies was healthy.
The scientists wanted to find out how things stood after
a longer amount of time and again collected more than 200 butterflies last
September. Twenty-eight percent of the butterflies showed abnormalities, but
the rate of mutated offspring jumped to 52%, according to researchers. The
study indicated that second-generation butterflies, the ones collected in
September, likely saw higher numbers of mutations because they were exposed to
the radiation either as larvae or earlier than adult butterflies first collected.
To make sure that the nuclear disaster was in fact the
cause of the mutations, researchers collected butterflies that had not been
affected by radiation and gave them low-dose exposures of radiation and found
similar results.
"We conclude that artificial radionuclides from the
Fukushima Nuclear Power Plant caused physiological and genetic damage to this
species," the study said.
The results of the study bring up concerns about the
larger impact of the Fukushima disaster and the impact it will have on the
ecosystem in Japan and nearby areas, as well as what we can learn for future
nuclear disasters.
"Our results are consistent with the previous field
studies that showed that butterfly populations are highly sensitive to artificial
radionuclide contamination in Chernobyl and Fukushima," the study said.
"Together, the present study indicates that the pale grass blue butterfly
is probably one of the best indicator species for radionuclide contamination in
Japan."
One of the researchers, Joji Otaki, an associate
professor at the University of the Ryukyus in Okinawa, told reporters that
while butterflies may be the best indicator, the study should also lead to more
research on what else may be affected by the radiation.
"Sensitivity (to irradiation) varies between
species, so research should be conducted on other animals," Otaki told the
Japan Times.
Otaki said while there is still plenty of research to be
done on radiation, there shouldn't be large-scale concern about this kind of
mutation in humans.
"Humans are totally different from butterflies and
they should be far more resistant" to radiation, he told the newspaper.
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