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. TheBigSarge

    so how come the communist news network is calling these "mutant" butterflies instead of "evolved" butterflies? i know, they are going to blame it on global warming and therefore bush 43? 🙂


    August 14, 2012 at 5:23 pm | Report abuse |
    • harryhaller

      King George II is not evolved one single tiny bit, but he is a mutant fascist draft dodger!

      August 14, 2012 at 5:31 pm | Report abuse |
    • steve harnack

      So why are you here? Aren't you afraid that your brain might pick up some liberal bug? I guess that if CNN dirties your mind you can pop over to Fox for a quick brain wash, eh?

      August 14, 2012 at 5:58 pm | Report abuse |
    • really

      Why, oh why do the trolls need to make everything political?

      August 14, 2012 at 6:12 pm | Report abuse |
    • mendrys

      A bit challanged in the reading comprehension department eh? You do understand that CNN is reporting on a peer reviewed study on the mutant butterflies and is not the author of the study don't you?

      No worries though, this is typical banter on this particular blog so you are not alone in your willful ignorance.

      August 14, 2012 at 6:23 pm | Report abuse |
  2. The Pope

    How to screw up the world in one easy lesson. Sure am glad that nuclear power is "safe".

    August 14, 2012 at 5:25 pm | Report abuse |
  3. Mugoman

    Butterfly crime scene, Butterfly crime scene......

    August 14, 2012 at 5:37 pm | Report abuse |
  4. zoosphere

    This is something expected, but this also shows what science can do.

    August 14, 2012 at 5:40 pm | Report abuse |
  5. nomus

    What next, Godzilla rising from the sea?

    August 14, 2012 at 5:45 pm | Report abuse |
  6. Lepidopterist

    Please call them by their correct name. Teenaged Mutant Ninja Butterflies. Thank you.

    August 14, 2012 at 5:56 pm | Report abuse |
  7. the_dude

    This is all happening according to plan. This is just the beginiing.

    August 14, 2012 at 6:02 pm | Report abuse |
  8. Byrd

    Perfectly safe, folks. Nothing to fear. Just ask my two-headed, four-armed son.

    August 14, 2012 at 6:33 pm | Report abuse |
  9. richard svalesen

    Somehow they will make their way to the US like the Carp and Lion-fish

    August 14, 2012 at 6:49 pm | Report abuse |
  10. Cb4nu

    "Humans are totally different from butterflies and they should be far more resistant" to radiation, he told the newspaper.

    August 14, 2012 at 7:05 pm | Report abuse |
    • Pen NM

      I hope you all feel reassured ... I don't.
      Golly gee whiz, perhaps there should be studies on other animals!

      August 14, 2012 at 7:13 pm | Report abuse |
  11. Surfer George

    "If I had even one active brain cell, I'd have come up with something intelligent."

    August 14, 2012 at 7:12 pm | Report abuse |
  12. Oltan

    I don't believe it. Remember, this will be found out to bogus, just like the power line effects, ect. These so called scientist must have some connection to anti nuclear groups.

    August 14, 2012 at 7:22 pm | Report abuse |
    • Kix

      Yeah, that's it. Another conspiracy. Goggle the pictures.

      August 14, 2012 at 7:35 pm | Report abuse |
    • rincali

      What is "ect?"

      August 14, 2012 at 9:12 pm | Report abuse |
  13. joe


    August 14, 2012 at 7:22 pm | Report abuse |
  14. Dragon Brain

    Project Mothra is going well, let us just hope Gamera does not emerge the nearby watershed

    August 14, 2012 at 7:29 pm | Report abuse |
    • Seth

      HAHAHAHA Nice. I was just going to post a mothra joke ;).

      August 14, 2012 at 7:58 pm | Report abuse |
    • kosh

      I wouldn't worry so much about Gamera, he was an heroic daikaiju. I'd be more worried about Battra or Gojira showing up.

      August 14, 2012 at 9:42 pm | Report abuse |
  15. Lizzy10

    Mothra, is that you?

    August 14, 2012 at 7:51 pm | Report abuse |
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