Fear of radioactive fallout from nuclear plant meltdowns in Japan has prompted a virtual buyout of a pill promoted as a "radiation protection tablet" by a manufacturer.

Major drug retailers in Hawaii have almost run out of the over-the-counter pill made of potassium iodide.

Meanwhile, the state will add two more radiation tracking devices — one on the North Shore and another on Kauai — to warn of any radiation plumes that come from Japan.

State Civil Defense spokeswoman Shelly Ichishita said that based on federal reports, Hawaii is not expected to experience harmful levels of radioactivity.

President Barack Obama said yesterday he has been assured that Hawaii and the West Coast will not be affected by radiation released from Japan.

Ichishita said her agency is not advocating that people buy potassium iodide pills.

State health officials said they have not detected abnormal levels of radiation, and "with the current size of the release and the distance from Hawaii, no public health risk to the state is expected."

Tom J. Miller, who owns parking lots here, said he found out about the shortage of potassium iodide after going to drugstores to try to buy the pills for his employees.

"It doesn’t hurt to be a little cautious," he said yesterday, noting he’s looking elsewhere for a supplier. "I think we’re planning to get some from Chicago."

The U.S. Food and Drug Administration has said potassium iodide in correct doses can block radioactive iodine in the thyroid and reduces the risk of thyroid cancer in radiation emergencies.

But the FDA said potassium iodide is not a general radioactive protective agent. The state Health Department advised against taking the substance because of the low risk of radiation here, and ingesting it "is not an effective precautionary measure."

The FDA said people with known iodine sensitivity, dermatitis herpetiformis and hypocomplementemic vasculitis should avoid consuming potassium iodide.

The FDA said people with multinodular goiter, Graves’ disease and autoimmune thyroiditis should use potassium iodide with caution.

Officials for Walgreens in Kailua and Longs Drug Stores said they did not know when the stores would have potassium iodide back in stock.

Vim N’ Vigor at Ala Moana Center said before the crisis in Japan, it was selling the tablets as a diet supplement for thyroid support and had about 10 to 20 bottles in stock.

But Vim N’ Vigor manager Tiffany Nakano said with the nuclear meltdown in Japan, "our store ran out of it on Saturday."

Drug manufacturer Anbex Inc., which promotes potassium iodide as radioactive protection, said it ran out of its stock supply Saturday and is expected to make more for delivery by April. Anbex said the orders have come from within the United States, especially from California.

Hawaii has two radiation tracking devices, one on Oahu on the roof of the state Department of Health building, and another on Hawaii island.

The state has used air monitoring devices for 20 years. In 1999 the state Health Department closely watched results after the Tokaimura nuclear accident in Japan, which killed two people. No radioactivity was detected in Hawaii at that time, health officials said yesterday.

Analysts in Hawaii examine the device’s filter twice a week, said Lynn Nakasone of the Health Department’s Environmental Health Services Division.

In addition, a satellite dish on the device transmits data in real time to U.S. Environmental Protection Agency analysts in Montgomery, Ala.

Should the crisis in Japan worsen, Hawaii would get three to four days’ warning before any radioactivity could reach here. The federal government would also send planes through the plume to analyze the radioactive material in the air.

If a worst-case scenario of a radiation plume hovering over the isles should occur, the state would ask residents to "shelter in place." Shelter in place means to take immediate shelter wherever you might be.

The state would also set up stations to distribute potassium iodine, which helps prevent thyroid glands from radioactivity.

"But we really don’t think it’ll come to that point," said Loretta Fuddy, interim state health director.