Radiation samples collected by the state air monitors at Sequoyah and Watts Bar nuclear plants last week detected radioactive isotopes from the Fukushima Dai-ichi nuclear crisis in Japan, but officials say there has been no threat to public health.

Tisha Calabrese-Benton, spokeswoman for the Tennessee Department of Environment and Conservation, said routine and ongoing air monitoring has shown the presence of very low levels of iodine 131, an isotope linked to the Japanese power plant.

"These detections are 1,000 to 10,000 times below any levels of concern," Calabrese-Benton said. "They are within the range expected and are far below levels of public health concern," she said.

Within hours after the announcement, Tennessee Department of Health Commissioner Susan R. Cooper in a news release said residents have no need to purchase or take potassium iodide, a chemical compound that can be used for short term protection of the thyroid gland from exposure to radioactive iodine, only one of many radioactive materials that may be released from a nuclear power plant.