Mutant butterflies a result of Fukushima nuclear disaster, researchers say
This image from a study on Fukushima's impact on butterflies shows wings mutated by the radiation.
August 14th, 2012
10:35 AM ET

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.

Read more:

Inside Fukushima's meltdown zone

What Fukushima did to the ocean

Gallery: Then and now

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Filed under: 2011 tsunami • Animals • Insects • Japan
soundoff (316 Responses)
  1. TMNB

    Teenage Mutant Ninja Butterflies

    August 14, 2012 at 3:39 pm | Report abuse |
  2. sbp

    JohnQ: Mutations due to human contamination can absolutely give rise to natural selection. It doesn't mean they will. The mutation may not have arisen from the same cause as a more "typical" mutation, but what happens from there follows the same path. If the mutation confers a reproductive advantage, the population will start reflecting that.

    August 14, 2012 at 3:40 pm | Report abuse |
  3. Typical Stay-at-Home Mom

    i r fat and ugly and like food stamps. me make babies to get maor money for free. I hate the 1%. OBAMA2012 or else I'll have to get a job. DON'T MAKE ME GET A JOB VOTE FOR OBAMA

    August 14, 2012 at 3:46 pm | Report abuse |
    • Charlotte your name is Ann Romney?

      August 14, 2012 at 4:00 pm | Report abuse |
    • Hope

      I'll bet you're dat and so much more...

      ... 42 years old, never been kissed, savin'
      your pay for a rainy day and still livin' with
      Mom and Dad. Knows everything there is
      to know about raising someone else's kids!


      August 14, 2012 at 5:35 pm | Report abuse |
  4. Jeff Cox

    I wonder if "Mothra" is available for instant download at Amazon .... hmmmmm ...

    August 14, 2012 at 3:48 pm | Report abuse |
  5. Hope

    HAMMER time is right!

    Beat the drums...


    Eyes, Open...

    August 14, 2012 at 3:49 pm | Report abuse |
  6. Ted

    This post is useless with out pictures of Mothra.

    August 14, 2012 at 3:53 pm | Report abuse |
  7. Lori


    August 14, 2012 at 3:55 pm | Report abuse |
  8. Lori

    But in all seriousness, those are some scary number.

    August 14, 2012 at 3:57 pm | Report abuse |
  9. PushingBack's Mothra?! You know what happens next, right??

    August 14, 2012 at 4:01 pm | Report abuse |
  10. sybaris

    Hora, hora, hora Godzirra!!

    August 14, 2012 at 4:06 pm | Report abuse |
    • Gary

      You mean Mothra.

      August 14, 2012 at 4:21 pm | Report abuse |
  11. Ron

    We have a story about Mutant Butterflys but ignore a story about 54 Million being hid by Calif Democrats in a bankrupt state? I dont get it CNN but again all I have to do is watch your slant commentators and I know the answer. BIAS

    August 14, 2012 at 4:10 pm | Report abuse |
    • Ron Izza Moron

      Ron. You are an idiot. What on earth does the California budget have to do with this story? On top of that, you blame the democrats? You are an narrow minded tunnel visioned moron!

      August 14, 2012 at 4:26 pm | Report abuse |
    • Ruby

      Must you people whine so much?

      August 14, 2012 at 4:29 pm | Report abuse |
    • KWDragon

      Hey Ron, If all you want to read is political news, please do so. Some of us care about other things as well, hence, this story.

      August 14, 2012 at 4:32 pm | Report abuse |
    • Snoozie

      You sound like a one-note trumpet.

      August 14, 2012 at 4:41 pm | Report abuse |
    • Tadpole

      Maybe if your comment made more sense, they would be able to pick up on the story.

      August 14, 2012 at 4:48 pm | Report abuse |
    • Hope



      (wavin' at Ron)

      August 14, 2012 at 5:39 pm | Report abuse |
  12. coop

    Not Godzilla, silly.


    August 14, 2012 at 4:15 pm | Report abuse |
  13. Muhammad

    I say we ban nuclear power and go back to ONLY coal and oil. Cheap and eco friendly!!! Oh, wait a second...

    August 14, 2012 at 4:23 pm | Report abuse |
  14. Ahmadullah

    It is Allah's punishment to the infidels – Join me in Islam, brothers and sisters.

    August 14, 2012 at 4:25 pm | Report abuse |
    • Hope

      I hear Iran is accepting charity
      to clean up their mountain...

      Sorry, HE already gave!


      UnBreakable Axis of What?


      August 14, 2012 at 4:56 pm | Report abuse |
  15. Ahmadullah

    In the name of Allah – I command you infidels to convert to Islam the most peaceful religion in the universe.

    August 14, 2012 at 4:26 pm | Report abuse |
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