Which is not very radioactive at all, by the way, but is in circulation according to the New York Times:

The alarm was sounded on Wednesday, when federal officials announced that tests had detected a trace amount of iodine 131 — a radioactive byproduct released by leaks at the Fukushima Daiichi nuclear plant in Japan — in a sample taken on March 25 in Spokane, Wash. The level of radiation was tiny and would have to be more than 5,000 times higher to reach the “intervention level” set by federal officials.

Jason Kelly, a spokesman for the Washington State Department of Agriculture, said the positive sample came from a gallon of pasteurized whole milk produced at the Darigold plant in Spokane, which processes milk from a number of farms in Washington and Idaho.

Jim H. Klein, a spokesman for Darigold, said milk from the Spokane plant was distributed in the Northwest, but said there was no reason for concern.