Monitoring efforts taken along the West Coast of the United States and Canada have revealed that radiation from the 2011 Fukushima Daiiachi nuclear power plant disaster is still washing in. However, don't let the media hype fool you. Experts are quick to add that the trace amounts of radiation discovered is completely harmless to humans.

In fact, according to Ken Buesseler, a chemist from the Woods Hole Oceanographic Institution (WHOI), the telltale radioactive compound that was detected, called censium, was at concentrations more than 1,000 times lower than acceptable drinking water limits set by the US Environmental Protection Agency (EPA).

"Most people don't realize that there was already cesium in Pacific waters prior to Fukushima, but only the cesium-137 isotope," Buesseler said in a statement. "Cesium-137 undergoes radioactive decay with a 30-year half-life and was introduced to the environment during atmospheric weapons testing in the 1950s and '60s. Along with cesium-137, we detected cesium-134 - which also does not occur naturally in the environment and has a half-life of just two years. Therefore the only source of this cesium-134 in the Pacific today is from Fukushima."

According to the WHOI, thanks to their incredibly low concentrations (less than 2 Becquerels per cubic meter of water) it was actually very difficult to detect these compounds at all, which explains why the general public didn't hear about this sooner.

"We don't know exactly when the Fukushima isotopes will be detectable closer to shore because the mixing of offshore surface waters and coastal waters is hard to predict," Buesseler added. "Mixing is hindered by coastal currents and near-shore upwelling of colder deep water."

According to the chemist, the offshore radioactivity reported this week came from water samples collected and sent to Buesseler's lab for analysis in August by a group of "Our Radioactive Ocean" volunteers on the research vessel Point Sur sailing between Dutch Harbor, Alaska, and Eureka, California.

This kind of crowd-sourced data has proven incredibly helpful for researchers, where federal agency monitoring alone has proven not enough for tracing this hard-to-find radiation.

"The models predict [West Coast] cesium levels to increase over the next two to three years, but do a poor job describing how much more dilution will take place and where those waters will reach the shore line first," explained Buesseler. "So we need both citizen scientists to keep up the coastal monitoring network."