Experts say that in terms of public health, the Japanese have already taken precautions that should prevent the accident from becoming another Chernobyl, even if additional radiation is released.
The Japanese government has evacuated people closest to the plant, told others to stay indoors and distributed the drug potassium iodide to protect the thyroid gland from radioactive iodine.
The tragedy of Chernobyl was an epidemic of thyroid cancer among people exposed to the radiation as children — more than 6,000 cases so far, with more expected for many years to come. There is no reason for it to be repeated in Japan.The epidemic in Chernobyl was preventable and would probably not have happened if people had been told to stop drinking locally produced milk, which was by far the most important source of radiation. Cows ate grass contaminated by fallout from the reactors and secreted radioactive iodine in their milk.
Apart from the increase in thyroid cancer, "there is no evidence of a major public health impact attributable to radiation exposure two decades after the accident" at Chernobyl, in part because of the evacuation efforts, said a recent United Nations report.
The thyroid gland needs iodine and readily takes in the radioactive form, which can cause cancer. Children are especially vulnerable.
Radioactive iodine has a half-life of only eight days — the time it takes for half of it to decay or disappear — so most of it is gone within about two months.
But radioactive forms of the particulate cesium persist much longer, and in the regions affected by Chernobyl, they are still the main threats to human health and will be for decades.