A team of scientists from the Woods Hole Oceanographic Institution on Thursday reported that they have detected higher levels of radiation linked to the 2011 Fukushima nuclear accident.

Researchers said they have so far sampled a number of sites and those sites are showing signs of contamination.

Ken Buesseler, the Woods Hole scientist who was the first to begin monitoring radiation in the Pacific after the accident, said in a statement that their recent findings have a crucial importance.

Firstly he said although the levels of radiations detected are far below government-established safety limits for human health or to marine life, their presence suggests that there is high need for closely monitoring the levels of contamination.

“Secondly, these long-lived radioisotopes will serve as markers for years to come for scientists studying ocean currents and mixing in coastal and offshore waters”, said Buesseler.

Earlier in October 2014, Buesseler reported that the samples from about 745 miles west of Vancouver, British Columbia, tested positive for cesium-134, called the fingerprint of Fukushima.

Later in November 2014, he reported that Fukushima radiation had been identified in 10 offshore samples. One of the sample was from 100 miles off the coast in Eureka, California.

Buesseler’s team in April 2015 once again reported that they found Fukushima radiation in a sample of seawater taken from a dock on Vancouver Island, British Columbia. This was for the first time when they recorded radiation on West Coast shores.

Latest sample results by Buesseler’s team include 110 new samples, and the samples collected about 1,600 miles west of San Francisco included highest level of radiation detected till date.