The detection of trace amounts of radioactive isotope iodine-131 this week in milk being sold in Spokane has raised anew questions about the extent of radiation exposure from the Japanese nuclear crisis.
But officials say people are exposed to more radiation from being in their homes each day than from drinking milk.
The Spokane area has higher naturally occurring radiation levels than other parts of the state, but that is mostly due to elevated radon levels in the soil, said Dr. Joel McCullough, Spokane County health officer.
Indeed, homeowners here have been urged for decades to have their homes tested for radon, which can be abated.
There is no danger from milk in this region, officials said, nor is there a radiation danger posed by drinking water or precipitation.
The Environmental Protection Agency tests milk at 30 locations across the country every three months, said spokesman Mark Macintyre. The federal agency has bolstered testing in Western states in response to the Japan nuclear accidents, and McCullough said that he anticipates more frequent testing in Spokane.
The tests were taken from milk samples collected by the Washington state Department of Agriculture, which pulled one gallon from a Darigold distribution center in Spokane County.
Darigold is the dominant dairy cooperative in the region, collecting milk from throughout Eastern Washington and North Idaho.
McCullough said the milk sample was run through several hours of testing to obtain the most accurate radiation readings. Such sampling usually takes just minutes.
The sample revealed that the milk had 0.8 picocuries of iodine-131 per liter, an infinitesimal amount that poses no public health risk and no public health concerns for regulators, McCullough said.
Picocuries are units of radioactivity. It would take 4,600 picocuries per liter for milk to be considered unsafe.
Iodine-131 has a half-life of about eight days, thus the levels detected are expected to drop quickly.
Health officials have not yet said whether they can link the radiation to the Fukushima Dai-ichi nuclear plant in Japan that was damaged by the magnitude-9.0 earthquake and then swamped by the resulting tsunami.
The EPA has been conducting quarterly tests on milk since 1978, Macintyre said.
Spokane also is home to a RadNet air monitoring station.
EPA officials have attempted to quell concerns of radiation poisoning, reminding Americans that low levels of radiation exposure are present in daily life.