WEDNESDAY, Sept. 21, 2011 (HealthDay News) -- Traces of radioactive fallout from the Japanese nuclear reactor damaged in the March earthquake were detected around San Francisco Bay, scientists report, but at such low levels they posed no health risk to residents.
A magnitude 9.0 quake severely compromised the Fukushima Dai-ichi power plant on March 11, but just how far the radioactive fallout from the event traveled has been unclear, noted researchers reporting online Sept. 21 in the journal PLoS ONE.
They sampled rainwater in Berkeley, Oakland and Albany, Calif., from March 16 to 26, looking for abnormally high levels of radioactive isotopes of cesium, iodine and tellurium. The team, led by Eric B. Norman of the department of nuclear engineering at the University of California, Berkeley, also sampled vegetables and milk sold in the San Francisco Bay area, and weeds from the Oakland area.
The samples of rainwater, weeds and foods did contain higher-than-normal levels of radioactive materials, and testing showed "clear evidence of [nuclear] fission products," the researchers reported. Levels of radioactivity appeared to peak on March 24 before settling back to normal, they added.
However, because of the extremely short half-life (rate of decay) of the radioactive materials, "the levels of fallout that we have observed in San Francisco Bay area rainwater pose no risk to the public," the team wrote.
As for the levels found in vegetables and milk in March, they added that "the levels of activity observed in these samples also pose no hazard to the public."
Find out more about nuclear plant accidents and potential health risks to humans at the U.S. National Cancer Institute.