via Safecast.org / January 11, 2014 / Let’s make it clear: the release of radioactive contamination from the Fukushima NPP to the environment — the air, the land, and the ocean — is a massive disaster. There’s no other way to describe it. Radiation in the air spread far and wide, and was even detectable, though barely, on other continents, while radiation in the ocean is spreading more slowly but inexorably. We know that some of the fish caught off Japan have been too contaminated to be sold for human consumption, and that wide expanses of farmland in Japan have been contaminated as well. But what effects can be expected overseas?
Lately there have been quite a few reports of die-offs, dangerously contaminated fish, and other horrors in the Pacific Northwest which have been ascribed to the effects of radioactive contamination in the Pacific ocean from Fukushima. Many people are worried and unsure, others are convinced that these reports are factual, and the stories have found a ready audience, mainly through online media. We’ve addressed and debunked a few of them already. Could it possibly be true that hazardous levels of Fukushima ocean radiation have reached North American Pacific shores? If this hasn’t happened yet, is it likely to happen in the future? The consensus among the many ocean scientists who have been monitoring the phenomenon is that Fukushima radiation is beginning to reach the Pacific coast, the levels will be so low they will only be measurable with extremely sensitive equipment, and that while the risks to people will not be zero, they will be “insignificant.”
Let’s try to understand why.
The ocean has been naturally radioactive since primordial times, and received quite a lot of fallout during the nuclear weapons testing era. Chernobyl added additional radioactive contamination to all of the world’s oceans, though considerably more to the North, Baltic, and Black Seas than to the Pacific. In addition, the Sellafield accident released quite a lot of contamination into the Irish Sea, and nuclear accidents in other locations have contributed as well. Ocean scientists have been measuring and tracking the radiation from all of these sources for decades, and have given us a very good idea of how the radiation found in different parts of the world’s oceans differs, where it came from, and how it moves through the environment.
This historical knowledge has been very useful for understanding the effects Fukushima has had and will continue to have on the Pacific. Many excellent researchers from Japan and abroad have been investigating this closely since March 2011, and anyone who is hoping to know more about what impact Fukushima radiation will have on the ocean far from Japan– in Hawaii, Alaska, or near California, for instance — should become familiar with what Fukushima ocean studies have shown. These researchers’ collaborations have been a model of cooperation among nations and institutions, and while the picture is not yet complete, the outlines — how much radiation is in the ocean, where it will go, and when it will get there — have been fairly well estimated.
These scientists conclude that the the Cs137 levels in the waterborne Fukushima radiation now reaching the North American Pacific coast will peak at between about 0.004 and 0.010 Bq/L, compared to about 0.001-0.002 Bq/L before the accident, will stay that way for a few years, and should start declining again around 2017. Percentage-wise this means 2 to 10 times existing Cs levels, which we could say is a lot, especially since the entire Pacific will be affected. But when one considers that the added radiation represents only about 1/1000 or less of the 7.4 Bq/L of Cs 137 the US EPA allows in drinking water (Japan and the WHO both allow 10 Bq/L), most people would probably conclude that it represents a minuscule health risk if any even if you drank it. The same appears to be true concerning the risks presented by the migratory Pacific bluefin tuna caught off California that had detectable levels of Cs137 as well: someone who ate 2 kg of it a week for a year would raise their risk of fatal cancer by only 0.00002%.
As always, the Devil is in the Details. As a recent press release from the Woods Hole Oceanographic Institute points out, “This is an evolving situation that demands careful, consistent monitoring to make sure predictions are true.” Detailed summaries of the research and the conclusions after the jump.
So who’s checking?
There have been quite a few very informative papers about the impact of Fukushima radiation on the ocean. Some of the most useful include:
Aoyama, et al: Fukushima derived radionuclides in the ocean
Buesseler, et al: Fukushima-derived radionuclides in the ocean and biota off Japan
Buesseler: Fishing for Answers off Fukushima