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Radiation From Fukushima Disaster Reaches Oregon Coast (nypost.com)
An anonymous reader quotes a report from New York Post: Radiation from Japan's 2011 Fukushima nuclear disaster has apparently traveled across the Pacific. Researchers reported that radioactive matter -- in the form of an isotope known as cesium-134 -- was collected in seawater samples from Tillamook Bay and Gold Beach in Oregon. The levels were extremely low, however, and don't pose a threat to humans or the environment. In 2011, a 9.0-magnitude earthquake triggered a wave of tsunamis that caused colossal damage to Japan's Fukushima Daiichi nuclear power plant. The disaster released several radioactive isotopes -- including the dangerous fission products of cesium-137 and iodine-131 -- that contaminated the air and water. The ocean was later contaminated by the radiation. But cesium-134 is the fingerprint of Fukushima due to its short half-life of two years, meaning the level is cut in half every two years. Cesium-137 has a 30-year half-life. Particles from Chernobyl, nuclear weapons tests, and discharge from other nuclear power plants are still detectable -- in small, harmless amounts. While this is the first time cesium-134 has been detected on US shores, Higley said "really tiny quantities" have previously been found in albacore tuna. The Oregon samples were collected by the Woods Hole Oceanographic Institution in January and February. Each sample measured 0.3 becquerels, a unit of radioactivity, per cubic meter of cesium-134 -- significantly lower than the 50 million becquerels per cubic meter measured in Japan after the disaster.
What he's saying (poorly but about typical for someone untrained in the effect of radiation on biology) is that there is no proof that long-term exposure to low levels of radiation is dangerous. That's a huge-ass assumption we've been living with for the last century. We know high doses of radiation are harmful. So we drew a straight line interpolating it down to zero, which leads to the unsubstantiated conclusion that low levels of radiation are also harmful. But we figured better safe than sorry, and set up radiation limits and protocols as if it were true.
Animal population studies from Chernobyl are a mixed bag so far and do not clearly support this conclusion. If it were true that long-term low level radiation were unquestionably harmful, you'd expect to find a clear negative trend. But the trend so far is mixed. So more than likely the effects of long-term low level radiation exposure are much more nuanced - sometimes bad, sometimes neutral, and as the man said, sometimes good. The mathematics of adaptation would seem to bear this out. The rate at which a species can adapt to changing conditions would depend on (1) its rate of reproduction, and (2) the rate of DNA transcription errors induced by radiation. So too much radiation and the organism dies due to biological malfunction. Too little radiation and the species dies due to inability to keep pace with changing environmental conditions.