The amount of radioactive iodine measured in milk on the West Coast was so small that it did not rise above the normal background level of radiation. Still, it's the first evidence that radiation from Japan's damaged nuclear plant is making it directly into food produced in America, reports CBS News correspondent John Blackstone.
"Radiation can be a scary word, but I think it's important to remember that actually, we live surrounded by radiation every single day," said Blair Thompson of the Washington Dairy Products Commission.
In fact some of our most common food -- potatoes, carrots, bananas, Brazil nuts all contain radioactive potassium. The radioactive iodine measured in milk can be more dangerous because it concentrates in the thyroid.
Still, the amounts measured are 5,000 times lower than those that can cause health damage, even in growing children. But for many fear remains -- and that can cause its own problems.
"We actually see health damage -- not from the radiation but from the fear of the radiation," said Tom McKone of the Department of Environmental Health Sciences at UC Berkeley. "And it's very real!"
That level of concern is why a Los Angeles fish market that imports fish from Japan is now sending samples of everything it brings in to an Arizona lab for radiation testing.
"Bottom line, we want to make sure our customers are well-informed on what's going on and that the radiation has not affected the fish incoming to the United States," said Ray Watanabe of International Marine Products.
Everything imported from Japan is already tested for radiation at ports and airports. And on hundreds of rooftops across the country, radiation detectors take constant measurements.
"It's very sensitive and should be very reassuring to the public," said Eric Stevenson of the California Air Resources Board.
Although only tiny amounts of radiation from Japan have been detected in air and in milk, the fear of radiation is so great that even figures meant to reassure -- can instead cause alarm.