HONOLULU -- Ocean-borne radiation from the Fukushima nuclear disaster in Japan has not reached the shore of California and is unlikely to pose any threat to human health, two leading North American scientists said Monday.
The experts on the fallout's path across the Pacific Ocean presented their latest findings in Hawaii at the Ocean Sciences Meeting, a conference that brings together many of the world's foremost oceanographic researchers. They delivered their message amid lingering anxiety -- and misinformation -- about the potential of the 2011 accident to poison people living on the West Coast.
Ocean samples at several locations in California from La Jolla to Point Reyes have not detected elevated levels of cesium-137 and cesium-134, the primary radioactive substances emanating from the leak, said Ken Buesseler, a marine chemist at Woods Hole Oceanographic Institution in Massachusetts.
The radioactive material is expected to arrive in small quantities on the coast this spring. But two models for predicting ocean circulation, said John Smith of the Bedford Institute for Oceanography in Nova Scotia, estimate that cesium-137 amounts will top out at roughly 25 becquerels per cubic meter. That's at least 300 times less than would justify worries about contamination here.
"It's clearly not a health threat," said Smith, noting that his primary interest is tracing the course of the radioactive material to learn more about water circulation and mixing in the northern Pacific Ocean.
Not everyone has absorbed that message, however. In December, for instance, someone posted a YouTube video of a man registering radioactivity with a Geiger counter at a beach near Half Moon Bay. The title of the clip suggests a link to Fukushima. Though such a link has been debunked, the clip has nonetheless attracted more than 760,000 views.
To better educate the public as well as further his own research into the spread of Fukushima radiation, Buesseler recently launched a crowd-funding initiative to study ocean samples along the West Coast. The project allows people to invest, mentally and financially, in the scientific process by collecting the water themselves and paying to have Buesseler's team analyze it.
"No agency has taken on monitoring the west coast of America," Buesseler said regarding the impetus for the project.
Samples taken off the California shore so far show no cesium-134 and background levels of cesium-137, between 1.5 and 2 becquerels per cubic meter. Those cesium-137 levels stem from nuclear weapons testing in the Pacific Ocean in the 1950s and 1960s, Buesseler said.
The U.S. Environmental Protection Agency's maximum allowable amount of cesium-137 in drinking water is 7,400 becquerels per cubic meter, Buesseler said. Swimming in the ocean, he added, exposes a person to about 12,000 becquerels per cubic meter of potassium-40, a naturally occurring radionuclide.
To learn about Ken Buesseler's research into radiation levels in the waters of the West Coast, or to participate in it, visit http://ourradioactiveocean.org.