Educate Yourself

Should I be worried?

The ocean contains many small sources of naturally occurring radiation that in most places exceeds the dose provided by radioisotopes released from Fukushima. In addition, the remnants of nuclear weapons testing in the 1960s and 70s are also still detectable around the world. Except for locations on land in Japan and sites near the Fukushima Dai-ichi nuclear power plant, all of these sources combined pose little risk to human health. [ MORE ]

To describe the level of radiation in seawater samples, we use Bequerels (Bq), which equal the number of radioactive decay events per second, and report this number per cubic meter (1,000 liters or 264 gallons) of water. A typical sample will likely contain less than 10 Bequerels per cubic meter (Bq/m3) from cesium-137, thousands of times less than the radioactivity produced by naturally occurring isotopes such as potassium-40. By comparing the amount of cesium-137, which has a relatively long 30-year half life, and cesium-134, which has a much shorter, 2-year half life, we can “fingerprint” the contamination from Fukushima and estimate how much was released into the Pacific. To understand exposure, we need to consider this number as well as the type of radiation produced (alpha particles, beta particles, or gamma rays) and the method of exposure (external or internal). Exposure is reported in Sieverts (Sv) or, more commonly, milli-Sieverts (mSv, or 0.001 Sv). Background radiation—the amount we receive from cosmic rays—amounts to 2 mSv at sea level. A single dental x-ray provides an exposure of as low as 0.005 mSv. [ LESS ]

Frequently Asked Questions Find more Frequently Asked Questions about radiation from Fukushima HERE