Contaminated spinach and milk has been detected at farms up to 90 miles from Japan's ravaged nuclear plants.

Fukushima prefecture has asked all dairy farms within 18 miles of the Fukushima Daiichi nuclear plant to halt milk shipments. Spinach shipments from the entire prefecture have been stopped as well. The milk with elevated radiation levels was found on farms about 19 miles away from the plants, and contaminated spinach was found one prefecture to the south, in Ibaraki prefecture.

Iodine-131 in the tested milk was up to five times the level deemed safe by the government, and the spinach contained levels more than seven times the safety threshold. The spinach also contained elevated levels of cesium-137.

Iodine-131 and cesium-137 are two of the more dangerous elements believed to have been released from the plants in Fukushima. Each element has the potential to cause cancer in humans.

Japanese officials have reassured the public about food safety.

Yukio Edano, the chief Cabinet secretary, said spinach and milk were the only foods found to have abnormally high radiation levels. If consumed for a year, the level of radioactivity in the spinach would equal the radiation received in one CT scan. The level detected in milk would amount to just a fraction of that.

"These levels do not pose an immediate threat to your health," Edano said. "Please stay calm."

Experts say these reassurances are probably accurate, but because people are so afraid of radiation, they are likely to altogether avoid foods that have been identified as contaminated.

It "seems unnecessary to eat these" foods, said David Brenner, director of the Center for Radiological Research at Columbia University. "I wouldn't."

Experts advised people consuming milk and produce, particularly children and pregnant women, to take potassium iodide to saturate the thyroid gland with nonradioactive iodine, preventing it from absorbing the radioactive form (Belson/Tabuchi, New York Times, March 19). -- PK