The Food and Agriculture Organization, the International Atomic Energy Agency and the World Health Organization jointly pledged support to Japan on Wednesday in addressing possible nuclear radiation contamination in food in the areas surrounding the stricken Fukushima nuclear power plant.

A joint statement said the UN organizations "are committed to mobilizing their knowledge and expertise" to support the Japanese government in ongoing efforts to address food safety issues.

Radioactivity has been detected in some vegetables and milk, with radioactive iodine present in concentrations above Japanese regulatory limits. Radioactive iodine can accumulate in the body if ingested, increasing the risk of thyroid cancer, but decays naturally within weeks.

Of more concern are potentially dangerous levels of radioactive cesium, which can linger in the environment for many years and present longer-term problems for food production and threaten human health. Radioactive cesium has so far shown up in concentrations under regulatory limits, but experts are still monitoring its levels.

The agencies said there is no evidence that food has been contaminated in any other country.

The agencies advise that people avoid the following in areas confirmed to be seriously contaminated: consuming locally produced milk or vegetables; killing animals; consuming and harvesting aquatic animals and plants, including fish, shellfish, and algae; hunting; and gathering mushrooms or other wild or collected foods.