Mutant butterflies in Fukushima: What's next?

It is reported that genetic mutations were found in three generations of butterflies near the Fukushima nuclear plant that was crippled by an 8.9 scale earthquake followed by a 10-15 m high tsunami. Nuclear radiation released from the nuclear reactors spread all over the area and reached up to Tokyo, 200 km to the south. Tens of thousands of residents from the affected area within a radius of 20 km from Fukushima were evacuated to safer zones. Vast areas around the plant site were contaminated with radioactive materials. Plants and animals within the vicinity of the accident were exposed to radiations.
Nuclear radiations can damage the DNA and cause mutations. Genetic mutations are of two types: somatic and germ-line. Somatic mutations take place in non-reproductive body cells and hence cannot be inherited. Only the exposed person is affected by somatic mutations. Germ-line mutations occur in the eggs or sperms and can pass from one generation to another. It may be mentioned here that all DNA damages may not create health problems. The body has a built-in immune system to repair the damage. The immune system, however, is not always effective.
Normally, several mutations are needed to damage or kill a body cell. Germ-line mutations can affect fertility and cause abnormalities in future off-springs like what happened among butterflies around Fukushima. The mutant butterflies in Fukushima had shorter wings and damaged eyes.
Such abnormalities naturally raise questions whether similar mutations are possible among humans exposed to radiation. The news of the existence of mutant butterflies must be worrying the residents exposed to radiations in and around Fukushima. The likelihood of human mutation has been under investigation for a long time, particularly since the detonations of two atom bombs in Nagasaki and Hiroshima in 1945.
A 40-year study was conducted among 100,000 survivors of the two atom bombs and their 70,000 offspring. It revealed that "radiation exposure did not cause genetic damage that could lead to human mutations." According to researcher John Boice of the National Cancer Institute: ''Ionising radiation is known to cause heritable mutations in many species of plants and animals, but intense study of 70,000 offspring of atomic bomb survivors has failed to identify an increase in congenital abnormalities, cancer, chromosome aberrations or mutational blood protein changes.''
The survivors' major health problem was cancer. It may be recalled that an estimated total of 90,000 to 166,000 victims died in Nagasaki and Hiroshima by direct blasts, burns, radiation, cancer and other long term effects. Children exposed to radiation had impaired growth. Referring to a report from Britain that "men who worked at a large nuclear fuel reprocessing complex near Sellafield fathered children who developed leukemia" Boice suggests that "other factors might be the cause of the leukemia cases near Sellafield."
After the nuclear accident at Chernobyl in Ukraine 1986, the area around the nuclear reactor was evacuated. Four square kilometres of pine forest close to the reactor became "ginger brown and died, earning the name of The Red Forest. Some animals in the worst-hit areas also died or stopped reproducing." After evacuation of humans, the exclusion zone turned into a safe haven for birds and animals. Many species, not previously seen around the area, also moved in and their populations have been thriving. No genetic abnormality among their offspring was detected.
High background radiation is found in the coastal belt of Karunagappally, Kerala, India because of the presence of thorium rich monazite sand. A study conducted in 1990s among the residents of the coastal belt showed no abnormal occurrences of cancer or leukemia.
Genetic mutation among the residents around Fukushima is most unlikely in view of the findings of the studies conducted in Nagasaki, Hiroshima and Chernobyl.
If there is an accidental release of radiation from any nuclear facility, immediate steps are taken to seal all paths of radiation leakages. Simultaneously, the affected area is evacuated as early as possible and the population is moved to a safe zone in order to minimise the exposure to radiation. The probability of cancer and leukemia cases among the civilian population thus remains very low.
Only a few cases of immediate radiation sicknesses were reported among the plant operators after the Fukushima accident though there was no fatality due to exposure to radiation. It is too early to say how many plant workers will suffer from leukemia or cancer. Even though the doses of radiation received by the workers were monitored carefully, the probability of such diseases among them cannot be ruled out.

The writer is a former chief engineer of Bangladesh Atomic Energy Commission and author of Rooppur & the Power Crisis, published recently.