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Japan Radiation Risks: FAQ

Answers to questions about health risks posed by Japan's damaged Fukushimi Daiichi nuclear power plant.

What is the best way to prevent radiation exposure?

 In the event of a nuclear accident, people living near nuclear power plants generally are provided with potassium iodide pills. That's because radiation leaks tend to carry radioactive iodine. The pills load the thyroid gland with iodine and prevent uptake of radioactive molecules.

But the best way to prevent radiation exposure is to stay indoors, close the windows, and turn off external sources of air, such as air-conditioning, until the all-clear is given or until you can safely be evacuated from a contaminated area.

"Contamination from fallout comes from touching a contaminated surface, from it falling, from inhaling it, or ingesting it," Williams says. "So in case of an event, be sure to drink bottled water and eat only sealed food that has not been outside."

Should I take potassium iodide pills?

 These pills can prevent radioactive iodine from collecting in the thyroid gland and causing thyroid cancer, but they don't undo all of the health effects of radiation.

Royal says there's no U.S. risk of radioactive iodine from the Japan nuclear emergency, so there is no reason to take the pills. Fortunately, if people panic and take the pills, they won't do any harm as long as they are taken as directed.

Royal notes that even if a person received enough radiation to cause radiation sickness -- 1,000 milisieverts -- the dose would increase their risk of cancer by 40%. To put this in perspective, smoking cigarettes increases cancer risk by 1,000% to 2,000%.

What are the health effects of radiation?

 Radiation risks are different for people at different stages of life:

  • Radiation has harmful effects on child development.
  • Radiation can induce cancers that appear years after an adult is exposed.
  • Elderly people's cells may have reduced ability to repair damage from radiation.

According to Lisandro Irizarry, MD, chair of emergency medicine at The Brooklyn Hospital Center in New York, symptoms of sudden (acute) radiation poisoning are nausea and vomiting. Other symptoms include fever, dizziness, disorientation, and bloody diarrhea. Symptom onset is quickest with the greatest radiation exposure.

The long-term effects of radiation exposure, Williams says, are the various cancers that can occur. The cancers most commonly associated with radiation are leukemia and cancers of the thyroid, lung, and breast.

In a year, the typical U.S. resident is exposed to 3 millisieverts of radiation, just as part of day-to-day life. By comparison, a chest X-ray is 0.02 to 0.67 millisieverts.

A person who receives a short-term dose of 1,000 millisieverts will experience radiation sickness but probably will survive. Short-term doses of 2,000 to 10,000 millisieverts have an increasing probability of causing a fatal cancer.

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