Countries across Asia and beyond are reporting small amounts of radiation from the disabled nuclear reactors in Japan. But officials say these levels are not a threat to public health.
On Tuesday, Chinese officials reported low levels of radioactive iodine-131 in areas of southeastern China. These include Guangxi, Guangdong and Shanghai. Earlier tests found the material in the northeastern province of Heilongjiang.
In South Korea, nuclear safety officials say they have found radioactive iodine in Seoul and several other areas.
Traces from the Fukushima power station have also been found as far away as Britain and the eastern United States.
Radioactive iodine loses half its strength in a week. But a more dangerous material, plutonium, has also been found in soil near the power plant.
Some medicines, like Prussian blue pills, can help expel radioactive elements from the body. But there are not a lot of treatments for radiation exposure.
The best known is potassium iodide. The pills flood the thyroid gland with non-radioactive iodine. The thyroid gland is a small organ in the neck that requires iodine for good health.
But people exposed to high levels of radioactive iodine can get thyroid cancer. The pills block the thyroid from absorbing radioactive iodine and reduce the cancer risk.
But the pills are not a cure for radiation sickness. And they work only if the radioactive iodine has been taken into the body through food or drink.
The World Health Organization is warning the public not to use potassium iodide unless health officials advise them to. WHO spokesman Gregory Hartl says the pills have their own risks.
GREGORY HARTL: "Indiscriminate use of the product can cause side effects such as inflammation of the salivary glands, nausea, rashes, intestinal upset and possible severe allergic reactions. It can also interact with other medications, especially certain types of cardiovascular medications such as ACE inhibitors, receptor blockers and potassium-sparing diuretics."
The crisis in Japan is the result of damage from the March eleventh earthquake and tsunami.
In the United States, the Armed Forces Radiobiology Research Institute is looking for more-effective treatments for radiation exposure. The institute is working with a company called Onconova on one possible treatment known as Ex-Rad. Onconova officials say Ex-Rad has shown promise in tests on animals, but several more years of research are needed.