The Environmental Protection Agency and the Food and Drug Administration in the U.S. say that very low levels of radiation have turned up in a sample of milk from Washington. But federal officials say consumers should not worry.

The FDA said such findings are to be expected in the coming days because of the nuclear crisis in Japan, and that the levels are expected to drop relatively quickly.

Results from a March 25 milk sample taken from Spokane, Wash., show levels of radioactive Iodine-131 that are still 5,000 times below levels of concern set by the FDA, including levels set for infants and children.

The EPA said it is increasing the level of nationwide monitoring of milk, precipitation and drinking water following the crisis at the Japanese nuclear power plant.

Tests on rainwater and seaweed earlier this month showed radiation from the Fukushima plant made its way to B.C.'s shores about seven days after radioactive steam blew off from the reactors there.

Slightly increased levels of radiation have also been detected in air samples taken from nine monitoring stations along the B.C. coast, but officials said the increases are minuscule and not a health concern.

There has been no sign of plutonium contamination in North America after some plutonium traces were detected outside the damaged reactors in Fukushima, Japan.

B.C. nuclear chemist Kris Starosta told CBC News Tuesday that scientists also would be monitoring for the radioactive chemical cesium 137, which can persist in the environment for up to 30 years.

Iodine 131 tends to break down in a matter of weeks.

With files from The Associated Press and the CBC's Priya Ramu