Radiation from Japan's 2011 Fukushima nuclear disaster has for the first time been detected along a North American shoreline, though at levels too low to pose a significant threat to human or marine life, scientists said on Monday.

Radiation from Japan's 2011 Fukushima nuclear disaster has for the first time been detected along a North American shoreline, though at levels too low to pose a significant threat to human or marine life, scientists said on Monday.

Trace amounts of Cesium-134 and Cesium-137 were detected in samples collected on February 19 off the coast of Ucluelet, a small town on Vancouver Island in Canada's British Columbia, said Woods Hole Oceanographic Institution scientist Ken Buesseler.

"Radioactivity can be dangerous, and we should be carefully monitoring the oceans after what is certainly the largest accidental release of radioactive contaminants to the oceans in history," Buesseler said in a statement.

The levels the group detected are extremely low. For example, swimming in the Vancouver Island water every day for a year would provide a dose of radiation less than a thousand times smaller than a single dental X-ray, Woods Hole said.

In March 2011, an earthquake and tsunami struck the Fukushima nuclear plant, 130 miles (209 km) northeast of Tokyo, sparking triple nuclear meltdowns, forcing more than 160,000 residents to flee from nearby towns, and contaminating water, food and air. It was the world's worst nuclear disaster since Chernobyl in 1986.

Buesseler said he expects similar low cesium levels to gradually reach other North American shores, possibly extending along the U.S. West Coast from Washington state to California.

"Predicting the spread of radiation becomes more complex the closer it gets to the coast," Buesseler said.

The Woods Hole Oceanographic Institution said its conclusions were drawn from research it collected from community groups and a network of local academics and aquariums to collect water samples and fund radiation testing.

Last November, Woods Hole reported detectable radiation from Fukushima about 100 miles (161 km) off the coast of northern California, but no radiation has yet been detected any closer to U.S. shores.

Tests off the coast of Japan shortly after the 2011 disaster measured radiation at 50 million Becquerels per cubic meter, Buesseler told Reuters. A "Becquerel" is a unit of radioactivity.

The Canadian water sample contained 1.4 Becquerels per cubic meter of Cesium-134 and 5.8 Becquerels per cubic meter of Cesium-137.

Reuters