Japan: Fukushima caused mutant butterflies say scientists

Source: AFP | Shingo Ito

Genetic mutations have been found in three generations of butterflies from near Japan's crippled Fukushima nuclear plant, scientists said Tuesday, raising fears radiation could affect other species.

Around 12 percent of pale grass blue butterflies that were exposed to nuclear fallout as larvae immediately after the tsunami-sparked disaster had abnormalities, including smaller wings and damaged eyes, researchers said.

The insects were mated in a laboratory well outside the fallout zone and 18 percent of their offspring displayed similar problems, said Joji Otaki, associate professor at Ryukyu University in Okinawa, southwestern Japan.

That figure rose to 34 percent in the third generation of butterflies, he said, even though one parent from each coupling was from an unaffected population.

The researchers also collected another 240 butterflies in Fukushima in September last year, six months after the disaster. Abnormalities were recorded in 52 percent, which was "a dominantly high ratio", Otaki told AFP.

Otaki said the high ratio could result from both external and internal exposure to radiation from the atmosphere and in contaminated foodstuffs.

The results of the study were published in Scientific Reports, an online research journal from the publishers of Nature.

Otaki later carried out a comparison test in Okinawa exposing unaffected butterflies to low levels of radiation, with the results showing similar rates of abnormality, he said.

"We have reached the firm conclusion that radiation released from the Fukushima Daiichi plant damaged the genes of the butterflies," Otaki said.

The quake-sparked tsunami of March 2011 knocked out cooling systems at the Fukushima Daiichi nuclear power plant, causing three reactors to go into meltdown in the world's worst atomic disaster for 25 years.

The findings will raise fears over the long-term effects of the leaks on people who were exposed in the days and weeks after the accident, as radiation spread over a large area and forced thousands to evacuate.

There are claims that the effects of nuclear exposure have been observed on successive generations of descendants of people living in Hiroshima and Nagasaki when the US dropped atomic bombs in the final days of World War II.

But Otaki warned it was too soon to jump to conclusions, saying his team's results on the Fukushima butterflies could not be directly applied to other species, including humans.

He added he and his colleagues would conduct follow-up studies including similar tests on other animals.

Kunikazu Noguchi, associate professor in radiological protection at Nihon University School of Dentistry, also said more data was needed to determine the impact of the Fukushima accident on animals in general.

"This is just one study," Noguchi said. "We need more studies to verify the entire picture of the impact on animals."

Researchers and medical doctors have so far denied that the accident at Fukushima would cause an elevated incidence of cancer or leukaemia, diseases that are often associated with radiation exposure.

But they also noted that long-term medical examination is needed especially due to concerns over thyroid cancer among young people -- a particular problem for people following the Chernobyl catastrophe.

"There are a number of unknown factors surrounding the genetic impact of radiation," said Makoto Yamada, a medical doctor who examines Fukushima residents. "We still cannot 100 percent deny that the impact may come out in the future."

No one is officially recorded as having died as a direct result of the Fukushima disaster, but many who fled the area and those who remain, including workers decommissioning the crippled plant, worry about the long-term effects.

Scientists have warned it could be decades before it is safe for some people to return to their homes.

"Even if there is no impact now, we have to live with fear," said Sachiko Sato, a mother of two, who temporarily fled from Fukushima. "And concerns will be handed down to my children and grandchildren."

Radiation and Pregnancy: A Fact Sheet for the Public

Source: Centers for Disease Control and Prevention (USA)

Note: If you are pregnant (or if you are thinking about getting pregnant) and you have questions about how radiation exposure could affect you or your pregnancy, you should talk with your doctor. Your doctor can help you better understand the risks of radiation exposure to you and to your developing baby.

The Centers for Disease Control and Prevention (CDC) has prepared this fact sheet to help you understand the possible health effects to your fetus from exposure to radiation.

Prenatal Radiation Exposure

The exposure of a fetus to radiation is referred to as prenatal radiation exposure. This can occur when the mother's abdomen is exposed to radiation from outside her body. Also, a pregnant woman who accidentally swallows or breathes in radioactive materials may absorb that substance into her bloodstream. From the mother's blood, radioactive materials may pass through the umbilical cord to the baby or concentrate in areas of the mother's body near the womb (such as the urinary bladder) and expose the fetus to radiation.

The possibility of severe health effects depends on the gestational age of the fetus at the time of exposure and the amount of radiation it is exposed to. Unborn babies are less sensitive during some stages of pregnancy than others. However, fetuses are particularly sensitive to radiation during their early development, between weeks 2 and 18 of pregnancy. The health consequences can be severe, even at radiation doses too low to make the mother sick. Such consequences can include stunted growth, deformities, abnormal brain function, or cancer that may develop sometime later in life. However, since the baby is shielded by the mother's abdomen, it is partially protected in the womb from radioactive sources outside the mother's body. Consequently, the radiation dose to the fetus is lower than the dose to the mother for most radiation exposure events.

Pregnant women should consult with their physicians if they have any concern about radiation exposure to their fetus.

Increased Cancer Risk

Radiation exposure before birth can increase a person's risk of getting cancer later in life.
Unborn babies are especially sensitive to the cancer-causing effects of radiation. However, the increased risks depend on the amount of radiation to which the baby was exposed and the amount of time that it was exposed. For example, if the radiation dose to the fetus was roughly equivalent to 500 chest x-rays at one time, the increase in lifetime cancer risk would be less than 2% (above the normal lifetime cancer risk of 40 to 50%).

Other Risks from Radiation Exposure

Health effects other than cancer from radiation exposure are not likely when the dose to the fetus is very low.
Most researchers agree that babies who receive a small dose of radiation (equal to 500 chest x-rays or less) at any time during pregnancy do not have an increased risk for birth defects. The only increased risk to these babies is a slightly higher chance of having cancer later in life (less than 2% higher than the normal expected cancer risk of 40 to 50%).

During the first 2 weeks of pregnancy, the radiation-related health effect of greatest concern is the death of the baby.
The fetus is made up of only a few cells during the first 2 weeks of pregnancy. Damage to one cell can cause the death of the embryo before the mother even knows that she is pregnant. Of the babies that survive, however, few will have birth defects related to the exposure, regardless of how much radiation they were exposed to.

Large radiation doses to the fetus during the more sensitive stages of development (between weeks 2 and 18 of pregnancy) can cause birth defects, especially to the brain.
When a fetus is exposed to large doses of radiation (above the dose received from 500 chest x-rays) during the more sensitive stages of development (especially between weeks 8 and 18 of pregnancy), the health consequences can be severe, especially to the brain. Fetuses in the  8- to 18-week stage of pregnancy exposed to the atomic bombs dropped on Hiroshima and Nagasaki were found to have a high rate of brain damage that resulted in lower IQs and even severe mental retardation. They also suffered stunted growth (up to 4% shorter than average people) and an increased risk of other birth defects.

Between the 18th week of pregnancy and birth, radiation-induced health effects (besides cancer) are unlikely unless the fetus receives an extremely large dose of radiation.
In the 18- to 25-week stage of pregnancy, health consequences similar to those seen in the 8- to 17-week stage could occur, but only when the doses are extremely large (more than about 5,000 chest x-rays received at one time). At this dose level, the mother could be showing signs of acute radiation syndrome, which is sometimes known as radiation sickness.

After the 26th week of pregnancy, the radiation sensitivity of the fetus is similar to that of a newborn.
At the 26th week of pregnancy, the fetus is fully developed though not fully grown. Unborn babies exposed to radiation in the womb during this stage of pregnancy are no more sensitive to the effects of radiation than are newborns. This means that birth defects are not likely to occur, and only a slight increase in the risk of having cancer later in life is expected.

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