Source is not to be taken too seriously. Didn't check the numbers. But anyhow apples are compared with oranges. . Water activity quoted is *not* released..Why compare it with releases from Chernobyl?. Fear-mongering? A most manipulatiive way of providing information.

Radioactivity is of course relatively easy to detect, unlike many other environmental pollutants. I've assayed rice from the Fukushima region by gamma spectrometry and the sample I measured was less radiotoxic than chocolate-coated brazil nuts. Factor in the massive dilution effect of the ocean and for myself I wouldn't be overly concerned about eating pacific pilchards.

We've being working with scientists in Fukushima regularly. We set up a lash-up whole body monitor system at a local hospital (in the low background room housing a non-operational monitor) and the first couple of times we went over we took measurements before leaving and on our return. The first trip, March 2012, produced a small 134/137Cs signal on return. By July, when I first went over, there was no measurable signal on our return. And, it wasn't as though we avoided local produce - some of our work has been with agricultural research centres who treated us to absolutely delicious fruit grown on their experimental plots on the outskirts of Fukushima City. Visiting scientists from Fukushima also sat on our lashed-up system, and showed much larger signals than those we got in a week or so over there. But, those signals were much reduced on subsequent visits.

So, on the basis of our experience, there is potential local effect through consumption of contaminated food. The levels the Japanese government have set are, however, very low (much lower than the EU set after Chernobyl) so there should be no food with significant levels of contamination on sale in Japan, or exported. Though, food grown and consumed at home without being sold is (to my knowledge) exempt, and Fukushima is a largely rural area with lots of small farms and cottage gardens. It is very unlikely any food reaching consumers outside Fukushima Prefecture would carry any significant (or, even measurable) levels of contamination.

No system is fool-proof, much less proof against people willing to bend the rules to make a profit, and so there probably still is some food above those levels entering the human food chain. There are checks on all food exports from the most affected prefectures in Japan, and random checks at ports of entry in the EU (and, probably elsewhere too). When we offered our services to provide additional verification to food suppliers we provide other services too in spring 2011 there was little interest - it seems to be generally felt that the Japanese monitoring of all exports and the random EU port of entry checks were sufficient. Without public concern, and pressure from the supermarkets, food suppliers didn't seem interested in spending money on more checks. And, more than two years later I suspect that any public concerns are even smaller.

Hey, guys. I found another claim being made that's floating around and wondered if you could comment on this as well. It didn't at all sound like anything mentioned here, so I figured it's probably just more nonsense, or perhaps a kernel of truth wrapped in nonsense. Any insight you can provide is appreciated. The fact that it starts with a universal claim (i.e. "All Bluefin...") doesn't, in my opinion, help its credibility.

ALL Bluefin Tuna Caught In California Are Radioactive: Every bluefin tuna tested in the waters off California has shown to be contaminated with radiation that originated in Fukushima. Every single one. Over a year ago, in May of 2012, the Wall Street Journal reported on a Stanford University study. Daniel Madigan, a marine ecologist who led the study, was quoted as saying, “The tuna packaged it up (the radiation) and brought it across the world’s largest ocean. We were definitely surprised to see it at all and even more surprised to see it in every one we measured.” Another member of the study group, Marine biologist Nicholas Fisher at Stony Brook University in New York State reported, “We found that absolutely every one of them had comparable concentrations of cesium 134 and cesium 137.” That was over a year ago. The fish that were tested had relatively little exposure to the radioactive waste being dumped into the ocean following the nuclear melt-through that occurred at the Fukushima Daiichi plant in March of 2011. Since that time, the flow of radioactive contaminants dumping into the ocean has continued unabated. Fish arriving at this juncture have been swimming in contaminants for all of their lives. When contact with radioactive cesium occurs, which is highly unlikely, a person can experience cell damage due to radiation of the cesium particles. Due to this, effects such as nausea, vomiting, diarrhea and bleeding may occur. When the exposure lasts a long time, people may even lose consciousness. Coma or even death may then follow. How serious the effects are depends upon the resistance of individual persons and the duration of exposure and the concentration a person is exposed to. If you will share this then probably few more people will be alert of this Danger.

The comment would appear to relate to Madigan etal, Radiocesium in Pacific Bluefin Tuna Thunnus orientalis in 2012 Validates New Tracer Technique, Environ. Sci. Technol., 2013, 47, 2287–2294 ( http://pubs.acs.org/doi/abs/10.1021/es4002423 ). I'm at home and don't have full access to the article, but the abstract says "All small PBFT (n = 28; recent migrants from Japan) had 134Cs (0.7 ± 0.2 Bq kg–1) and elevated 137Cs (2.0 ± 0.5 Bq kg–1) in their white muscle tissue. Most larger, older fish (n = 22) had no 134Cs and only background levels of 137Cs". Which is not quite the same spin as the reported Wall Street Journal statement: no suggestion of surprise that the tuna that have migrated from Japan carried very low activity concentrations of 134/137Cs. Plus, that EnvSciTech paper only observes 134Cs in the young fish recently arrived from waters near Japan, and not the older fish that have spend a year or more in the waters closer to California. In humans Cs is constantly exchanged between cells and has a biological half life of ~100days, there would (presumably, I'm not a marine biologist) be a similar mechanism in fish and the reported study suggests that the biological half life for that process is a) long enough for Cs to still be present after the journey across the Pacific and b) short enough that the activity has reduced to below detection limits in a year.

As for the part of the quoted material that starts "When contact with radioactive cesium occurs ... ". That's a not unreasonable description of the effects of acute radiation exposure. But, that would be from exposure to radioactive dose rates significantly larger than anyone received from the Fukushima accident - even those who remained on site fighting to bring the accident under control did not recieve doses that high (though, several may still suffer longer-term health effects). To even suggest that Cs in tuna could produce that sort of effect is scare mongering of the worst kind. If there was even a small fraction of the Cs in tuna to cause that sort of effect then it wouldn't enter the human food chain - the fish would be dead long before anyone could catch them.

Thanks for your insight, Alan.

Hey, guys. Would any of you be willing to comment on the reliability of this article?  Tracking such things is one of my passive interests, because they can easily ruin public perception, since they're not really run by groups of specialists.  Thanks in advance for any input!

http://www.iflscience.com/plants-and-animals/study-reveals-impact-fukushima-catastrophe-plants-and-animals

I'm not an expert in the field, and can't really comment on the specifics of the link and the articles linked to therein. But, something that has been a concern at the back of my mind is the definition of control groups for these sort of studies. Elevated levels of radionuclide activity is not the only variable. At both Chernobyl and Fukushima the areas where dose rates are significantly elevated are also areas where human influences have changed - the areas have often been evacuated, with land previously used for agriculture now fallow, collection of firewood from forests no longer happening etc. How do we know changes in average genetic patterns are due to radiation induced mutation rather than just selection due to changes in the ecosystem resulting from significant reductions in human activity?