A briefing for the California Coastal Commission ahead of its May 14 meeting concludes\u2014yes, radiation from nuclear power plant meltdowns at Fukushima, Daiichi March 11, 2011, reached, and still arrives on the California coast, but no, don\u2019t worry about it. \tThe Japanese meltdowns that polluted air and water with radioactivity \u201creached the California coast within four-seven days of the accident, resulting in detectable levels of airborne radioactivity in California,\u201d according to the staff report. It adds that an ocean plume carrying more isotopes \u201ccould possibly reach California within the next year.\u201d \tThe advisory tempers that information by noting that what\u2019s reaching the coast is \u201cexpected to be only slightly above the pre-accident background\u201d radiation levels. \tBackground levels are not static. They constantly change based on what levels are in recent history. In some parts of the world, what\u2019s considered background is much higher or lower than in other parts. \tWhile the Coastal Commission\u2019s report notes that radioactivity from the nuclear meltdowns has been \u201cmassively diluted,\u201d it adds that an ocean plume carrying more radioactivity is set to arrive at an unknown future date. And, even though the briefing minimizes exposure, it goes on to note that the U.S. Environmental Protection Agency\u2019s RadNet program tests food products with \u201climited frequency\u201d to establish any contamination.