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. nate

    mutant butterfies don't really worry me. what about mutant bacteria, or viruses? oh yeah, we won't know about those for a few years.

    August 14, 2012 at 8:02 pm | Report abuse |
  2. sharoom

    Thank you CNN for providing a link to the study.

    August 14, 2012 at 8:03 pm | Report abuse |
  3. Kix

    Lol , Surfer George

    August 14, 2012 at 8:05 pm | Report abuse |
  4. Ulug The Great

    First, human DNA is much more aboundant in non coding regions thus any mutations that will arise will only affect the junk portion of human DNA. Humans are more resistant b/c our ancestors have lived through nuclear exposure, talking about the early mammals during the K2 event that killed off all the Dino's. Finally Mutation is never good, if a virus was to be randomly mutated than it would only be rendered useless.. A mutation never have positive results such as in the XMAN movies

    August 14, 2012 at 8:36 pm | Report abuse |
    • Bazoing

      Some of this report concerning the actual crosses is a little crossed up. No one is certain that the 'junk part' of the human genome has a use or not. And since butterflies have been around longer than humans, or even mammals, I doubt that they have been exposed to less radiation. It is simply a case of this one group of butterflies being very susceptible. Go ahead and be frightened, we have reason.

      August 14, 2012 at 10:47 pm | Report abuse |
  5. mugzee

    I'll turn green if you make me angry!

    August 14, 2012 at 8:41 pm | Report abuse |
  6. TeddyG

    Wasn't this a movie ... back in the day?

    August 14, 2012 at 8:45 pm | Report abuse |

    Yep, let's just play possum and pretend nothing is wrong.

    Nuclear is honestly the safest and cleanest energy source available!!!

    Wanna buy this diamond ring I managed to steal for only 50 cents out of the gumball machine?

    August 14, 2012 at 9:20 pm | Report abuse |
  8. Rascal Rabble

    ...anyways I could use a glow in the dark butterfly to read under the covers....

    August 14, 2012 at 9:30 pm | Report abuse |
    • What, what?

      Lol. Glow Worms!

      August 14, 2012 at 9:33 pm | Report abuse |
  9. snowcarver75

    move along people, evolution doesn't exist..

    August 14, 2012 at 10:16 pm | Report abuse |
  10. Leonardo

    Maybe they'll find a mutant lizard,and then we'll get Godzilla vs Mothra,in real life!!!!!!!

    August 14, 2012 at 10:25 pm | Report abuse |
  11. TomTom

    And for those who are thinking where are the radioactive spiders? Don't even ask, there is no such thing as spiderman?

    August 14, 2012 at 10:26 pm | Report abuse |
  12. disgustedvet

    Evolution is filled with instances where mutations occurred. Some worked and "evolved " some did not. Not saying radiation couldn't enhance the chances ,just pointing out something "out of the agenda box " .

    August 14, 2012 at 10:44 pm | Report abuse |
  13. Ren

    Er, hello? Ever heard of the butterfly effect?

    August 14, 2012 at 11:50 pm | Report abuse |
    • crazycatman

      Yes I've heard of it, and it has nothing to do with this subject. Find out what you're talking about instead of just picking out a word you've heard somewhere.

      August 15, 2012 at 1:23 am | Report abuse |
    • Yo Mammy

      LOL @crazycatman!!

      August 15, 2012 at 4:02 pm | Report abuse |
  14. Allan

    They better be on the lookout for mutant ninja turtles now!

    August 15, 2012 at 12:11 am | Report abuse |
  15. Jack Wagon

    "No one ever suspects the butterfly..."

    August 15, 2012 at 12:30 am | Report abuse |
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