A health official thinks isotopes found here will match those found on the U.S. mainland
POSTED: 1:30 a.m. HST, Mar 25, 2011
Although the U.S. Environmental Protection Agency had yet to identify the radiation that arrived here Monday from Japan, a state health official said yesterday he expects the isotopes that have been detected on the West Coast to be seen in Hawaii, and in similarly low levels.
Radioactive iodine, cesium and tellurium have been confirmed in California and Washington. California also registered xenon, and health officials in Colorado and Oregon say traces of iodine have been picked up.
Jeff Eckerd, acting program manager of the Hawaii Health Department's indoor and radiological health branch, said he expects to see the same isotopes here.
"After the first sample (confirmation) comes out, I think we'll start to see (radiation) numbers coming out of the EPA pretty much on a daily basis," Eckerd said.
The EPA emphasized that the radiation levels in California and Washington were "hundreds of thousands to millions of times below levels of concern."
"I think the numbers are going to be low (in Hawaii), and it will even get significantly lower because iodine-131, tellurium-132 and xenon are relatively short-lived — I mean hours to days," Eckerd said. "It will decay out rather quickly."
Cesium has a longer life, and Eckerd said the Health Department probably will be tracking trace amounts of radioactivity in Hawaii "for months if not longer."
The average person is exposed to about 620 millirems of radiation a year from a variety of sources. According to the American Nuclear Society, a chest X-ray is 10 millirems, flying in a jetliner results in 0.5 millirems per hour and radon in the air can reach 228 millirems a year.
Television and computer screens can mean exposure to 1 millirem, and food and water contribute 40 millirems per year.
Health experts said 35,000 millirems is the lowest exposure of ionizing radiation that could lead to mild changes in the blood. It would be necessary to receive 3,500 chest X-rays for that dose. The EPA reported that normal "background" gamma ray exposure rates for Oahu typically range between 0.005 and 0.020 millirems per hour.
The EPA said the iodine-131 level detected in San Francisco was .0682 picocuries per meter cubed. It did not convert to millirems.
According to the agency, the threshold for shelter and evacuation to be "considered" for iodine-131 starts when people are subjected to 37 million picocuries per meter cubed in one hour, or 385,000 picocuries per meter cubed for 96 hours.
Eckerd said radiation that hit California on the jet stream might have swirled around in winds that hit Hawaii on Monday. He added that the delay in the EPA identifying the isotope that reached here might be due to a backlog of samples from the mainland that need to be identified.
"We really want to let people know we're tracking (the situation)," Eckerd said. "We don't expect this to happen, but if the situation escalates we will be notifying the public and they should listen to public health officials for any precautionary measures. But again, at this time we don't expect any harmful levels to reach Hawaii."