Washington (CNN) -- The U.S. Environmental Protection Agency said Wednesday it is increasing its nationwide monitoring of radiation in milk, precipitation, drinking water, and other outlets in response to the ongoing nuclear crisis in Japan.
The EPA already monitors radiation in those potential exposure routes through an existing network of monitoring stations across the country.
Results from a screening sample of milk taken March 25 in Spokane, Washington, detected radioactive iodine at a level 5,000 times lower than the limit set by the U.S. Food and Drug Administration, the EPA said.
The I-131 isotope has a very short half-life of about eight days, the EPA said, so the level detected in milk and milk products is expected to drop relatively quickly.
The tests confirm that the milk is safe to drink, Washington Gov. Chris Gregoire said.
"This morning I spoke with the chief advisers for both the EPA and the FDA and they confirmed that these levels are miniscule and are far below levels of public health concern, including for infants and children," Gregoire said in a statement.
"According to them, a pint of milk at these levels would expose an individual to less radiation than would a five-hour airplane flight."
FDA senior scientist Patricia Hansen also said the findings are "miniscule" compared to what people experience every day.
At least 15 states have reported radioisotopes from Japan's crippled Fukushima Daiichi nuclear plant in air or water or both. No states have recommended that residents take potassium iodide, a salt that protects the thyroid gland from radioactive iodine.
Iodine-131 has been found in eastern states from Florida to Massachusetts as well as in western states like Oregon, Colorado, and California, according to sensors and officials in those states.
None of the levels poses a risk to public health, they said.
The Japanese plant has been leaking radiation since it was damaged in the earthquake and resulting tsunami earlier this month.