Environment

Traces of Fukushima Radiation Detected Off California Coast

Extremely low levels of radioactive cesium from Japan's 2011 Fukushima nuclear meltdown are present in ocean water offshore Northern California, researchers announced Monday.

In seawater collected about 100 miles (161 kilometers) offshore of Eureka, the amount of cesium-134 was 2 Becquerels per cubic meter of water (a unit of measure based on the number of radioactive decay events per second per 260 gallons of water). That's about 1,000 times lower than the drinking water limit set by the U.S. Environmental Protection Agency.

This level of radioactivity does not represent a health hazard for people who want to fish or swim in the area, said Ken Buesseler, a marine chemist at the Woods Hole Oceanographic Institution in Massachusetts, who helped analyze the seawater. Buesseler is leading a crowdfunded citizen science program to track cesium levels from the meltdown by collecting water samples along the U.S. and Canadian West Coast.

A swimmer who spent 6 hours every day for a year in water with 10 Becquerels per cubic meter of cesium-134 would still receive 1,000 times less radiation than the dose from a single dental X-ray, Buesseler said. "Now, we have measurements that confirm that for human health, when a mother from Santa Cruz calls me and asks if it's safe for my son to go surfing, we have far fewer concerns," he said.

To date, no cesium-134 has been found at Canadian or U.S. beaches, including those in Hawaii, Alaska, Washington, Oregon and California. The short-lived isotope has only been detected offshore.