Breaking Down the Health Risks from Radiation

Most of what we know about radiation injury comes from the 1986 nuclear accident in Chernobyl, Ukraine. After a nuclear accident, people can be exposed to radioactive iodine and cesium. Some of the expected health risks from exposure:

Acute radiation sickness

Heavy radiation exposure can cause an illness that gets worse over several days. It causes these symptoms:

Vomiting
Bloody diarrhea
Fatigue and weakness
Rash
Poor wound healing
Crippling of the immune system

This illness can result in death from infection. The World Health Organization (WHO) and a group called the Chernobyl Forum studied the health effects of the Chernobyl accident. In the first year, about 350,000 people helped to clean up the radiation. These people accounted for most of those with heavy exposure. In all, 134 developed acute radiation sickness. In the first year after exposure, 28 died.

Thyroid cancer

The thyroid gland in the neck absorbs and stores radioactive iodine. We can inhale this chemical or absorb it through the skin. We also can swallow it in contaminated food or in milk from exposed dairy cows. Thyroid cancer was the major health result from the Chernobyl accident. Experts estimate that 5,000 cases occurred. Higher rates of this cancer began to appear 4 years later. It was especially common among exposed children. This increase occurred across a very large area -- up to 500 kilometers (310 miles) from Chernobyl. Thyroid cancer can be detected early and cured with surgery.

Taking iodine tablets at the time of a radiation exposure can help to prevent thyroid cancer. These tablets saturate the thyroid gland with iodine. This means it can't absorb the radioactive iodine. The body clears it out quickly through urine. After the Chernobyl accident, nearby Poland gave iodine pills to millions of its people. This action certainly helped to prevent some thyroid cancers.

Leukemia

Radiation also doubles the risk of leukemia for people with high exposure, such as clean-up crews. This was seen after Chernobyl and also after the atomic bombings in Japan.

Other cancers

The risk for other cancers also is increased. But this adds only a very small fraction to a person's total cancer risk, experts say.

Cataracts

Cataracts can result after fairly small exposures to radiation.

Social displacement and anxiety

The most widespread health impact of a nuclear accident is from the evacuation of people. Food and housing become scarce. People also are vulnerable to epidemics of infection.
The most important step that Japan will take if a reactor releases much radiation will be to evacuate nearby areas.

People in the area where a nuclear accident occurs also can take iodine tablets. This could greatly reduce the number of thyroid cancers. Iodine tablets can cause minor side effects. These include rash and stomach ache. Some people have severe allergic reactions to iodine.

Iodine tablets are not for everyone. They are only recommended for people younger than age 40 who are close enough to an accident to have a very large radiation exposure. This would be higher than 5 centi-Gray units, or cGy.

Iodine is not recommended for people exposed to less radiation.

Radioactive iodine breaks down quickly. The WHO report about Chernobyl says that having children stop drinking milk from local cows could have prevented most of the health problems from that accident.