Um, why is my sushi glowing?
September 12, 2013 4:10 PM   Subscribe

How do we know whether the fish we eat is essentially free of Fukushima radiation?

With the news of more actual and potential leaking of radioactive water at Fukushima, how do we know (no matter where we are in the world) whether it's safe (radiation-wise) to eat any kind of fish or other seafood, be it sushi in a restaurant, a frozen fish stick, grilled salmon at the local fish grill, or whatever?

I've seen this question from 2011 about seaweed, but with fish it seems like a very different situation because it comes from oceans all around the world and often doesn't have a place of origin label or record, at least not once it reaches the final consumer.

Do fish wholesalers and importers test all fish for radiation? Does the FDA have testing requirements? Are only very small random samples tested? Should we all be concerned about the possibility of radioactive seafood in our food supply?
posted by Dansaman to Food & Drink (12 answers total) 6 users marked this as a favorite
Unlike chemical elements, radio-active elements decay. The faster they decay multiplied by how much of it you have give an idea of how much damage they may cause. If they decay really fast, chances are they will have effectively disappeared by the time they reach your plate. If they don't decay very fast, chances are they will not have much chance to cause much trouble in the time they take to go through your digestive system. If they decay fast AND you have lots in a given fish ... chances are the fish will die before it is caught.

Things are different for non-radioactive elements. Take mercury: it is stable. It also accumulates in bodies and can cause major health problems. It is much more of a health risk than the slight increase in radiation that could be found in fish that swam near the damaged reactors in Japan.

btw, as you are reading this, you are exposed to byproducts of radio-active decays. If you live in Colorado, it is quite possible that the radiation exposure you get is much worse than those that live in nearby villages from the damaged Japanese reactor.
posted by aroberge at 4:19 PM on September 12, 2013 [3 favorites]

So, someone linked to this scare piece on facebook that talks about radioactivity in tuna, and I felt it necessary to tell the Internet it was wrong.

The article in question says the tuna are bioaccumulating 5 Bq/kg of Cesium 137 (source paper). While this sounds like a lot, it converts to an exposure of about 10^-7 sieverts per kilogram of contaminated tuna consumed. Thats .1 microsievert, or about the radiation exposure you get in eating a banana for every kg of tuna you eat.

At the moment? Empirical evidence says you shouldn't be too worried. Even though Fukushima is leaking a lot of radioactive water, the ocean is huge. Fukushima is just a really big piss in the ocean. It's bad, but it shouldn't be catastrophic, and heavy metal bioaccumulation is still a bigger deal from a health perspective.
posted by bfranklin at 4:20 PM on September 12, 2013 [10 favorites]

Radiation is at least something you can test for yourself; you don't have to take anyone's word for it, at least for fish you buy to prepare at home. If you don't end up getting clear answers to most of your questions (I would also love to know more about FDA testing requirements for seafood, given the Gulf of Mexico contamination as well), you can at least get an answer to "How do we know whether it's safe?" Buy your own Geiger counter and test your fish.

There's actually a small, affordable Geiger-counter kit you can order now that might be useful; some assembly is required, though, unfortunately. It seems we haven't come so far from the days when my father ordered and assembled his own Geiger-counter kit, presumably because it was the most affordable way to learn exactly what was around him, since for whatever reason, Geiger counters haven't become minified, cheap, and ubiquitous the way some other types of sensors have.
posted by limeonaire at 5:02 PM on September 12, 2013

This pocket Geiger counter on Amazon also looks potentially promising, if you're up for spending a little more.
posted by limeonaire at 5:13 PM on September 12, 2013

I don't think a geiger counter offers a useful way to test for bioaccumulated cesium, strontium, etc. Stuff that (even with computerized lengthy testing periods) is difficult to hear amidst background when shielded by the animal can still be an undesirable amount if it's the kind of thing that ends up deposited in your bones like calcium. It's not the case that just waving the wand over a fish will tell you anything useful.

A scintillator with adjustable energy window might start to get you there, but you're probably talking four figures, used and uncalibrated, for even that much.
posted by anonymisc at 5:17 PM on September 12, 2013 [2 favorites]

Do fish wholesalers and importers test all fish for radiation? Does the FDA have testing requirements? Are only very small random samples tested? Should we all be concerned about the possibility of radioactive seafood in our food supply?

I'm going to hazard the following guesses: "No", "no", "none*", and "not quite yet but ask again in a year... and check again in another year... and so on."
The good news is that I think we have the drop on this - as the problem slowly worsens (and it will worsen) it will attract more study, and there is time for that to happen. If it does become a health issue over here, I think we'll have a pretty good idea that it's becoming a health issue before it has become one.

*With the exception of scientific studies
posted by anonymisc at 5:31 PM on September 12, 2013

I answered "buy local," and it was deleted, but this is a serious answer intended to be helpful. In all honesty, you can know that your fish are not affected by radiation from this incident if you confine your seafood eating to locally landed fish. I don't think you can assume that any processed fish, of the kind you'd find in fish sticks and the like, was not from affected areas.
posted by Miko at 6:40 PM on September 12, 2013

Here's what Heal the Bay says
What the FDA says
Woods Whole Institute study
posted by biscuits at 6:43 PM on September 12, 2013 [2 favorites]

As a people, the Taiwanese have been fairly concerned with the consequences of the Fukushima plant disaster and how this may affect their country and the food they eat. Their island sits along tectonic fault lines and nuclear supplies about 8% of the country's power demand. While the US, Japanese and Chinese governments have not issued warnings about contaminated seafood (and probably would not) it is perhaps somewhat likely that Taiwan would. Due to geographic proximity to Japan, I'd suggest keeping an eye on Taiwanese media for coverage about its food supplies and any reports of radioactive contamination — you may hear reports from this country before you hear of any problems reported in the United States.
posted by Blazecock Pileon at 8:52 PM on September 12, 2013 [1 favorite]

There's actually a small, affordable Geiger-counter kit you can order now that might be useful

That seems not to be a geiger counter but only a gamma/xray detector.

Even if you had a proper geiger counter to also pick up alpha and beta particles, I expect that the only thing you would really learn is that lots of stuff is mildly radioactive. Like bananas, or granite.

Unless you're eating fish caught very near the reactor, you're going to be dealing with very minor increases of radiation over the existing baseline from nuclear tests in the 60s. Or, if you want to think about it that way, even if the event doubled the radiation in fish, that would still be about the amount of radiation you'd have seen in sushi in 1980.
posted by ROU_Xenophobe at 9:17 PM on September 12, 2013 [1 favorite]

Buy your own Geiger counter and test your fish.

This is hard to do right, and a good way to drive yourself crazy: for example, it is practically impossible to maintain a consistent counting geometry, determine appropriate background levels or get good statistics.

First you have to find a source for known clean fish (assuming there's dangerously radioactive fish out there, that is) of each variety you want to count and get some background measurements, to compare against the unknown samples. Counting a background with the same variety of fish is important - you don't want to be throwing out perfectly good fish because there's more pottasium in it than your reference samples. Then you would have to buy some extra fish every time, stuff it in a standard-size container and let it be counted for a few hours - you probably won't be eating it afterwards. Oh and also try to keep good ventilation in your counting room, to protect against false positives from accumulating radon daughters, and maybe buy a check source to make sure your detector is operating reliably.

The detection threshold you will get by just getting a Geiger counter and holding it against a piece of fish for a couple of minutes will probably be much higher than the level at which authorities would step in to pull stuff off the market: If there was enough Cs-137 in it to be detectable this way, a truckload of the same fish would have been setting off radiation detectors right and left. Not that every piece of seafood on the market gets tested, but if things were that bad, it would be obvious to authorities from e.g. containers of fish crossing radiation portals at ports and borders.
posted by Dr Dracator at 10:29 PM on September 12, 2013

"There's actually a small, affordable Geiger-counter kit you can order now that might be useful; some assembly is required, though, unfortunately."

No, that would be like trying to detect a fly by blindly waving around a long 2x4 in a china shop, there is no conceivable way you could possibly get useful information.

If you are near Leuven, Belgium or Olympia, WA and have a piece of fish you have particular concerns about, or are just curious about, memail me. I'd be happy to smush it up with you, suspend it in a special liquid that scintillates when exposed to the kind of radiation you are concerned about, and place it in a very expensive machine that is heavily shielded enough from cosmic radiation to detect radiation at levels that could be plausibly found in fish.
posted by Blasdelb at 6:22 AM on September 13, 2013 [3 favorites]

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