How safe is your sushi?

sushi_sm.jpg Even if you’re not pregnant, you have to be worried about toxic mercury levels in fish.

Mercury is a highly reactive heavy metal that’s present in raw fish, like sushi, and in canned fish, like tuna. Exposure to toxic levels of can cause damage to the nervous system and the renal system, but long term exposure at lower levels hardens arteries by inactivating antioxidant mechanisms.

In fact, high mercury content can diminish the cardiovascular benefits of fish consumption, so eating fish may not benefit your health after all (Guallar et al, 2002, N Engl J Med).

So how safe is your sushi? More and more, it’s safe to assume your fish is polluted. The data coming in from a smartly conceived project called “Got Mercury?” from the non-profit watchdog group Turtle Island Restoration Network indicates that high-end restaurants in major US markets are serving tainted fish. The group is running a brilliant campaign to collect and test samples from some of the finest sushi parlors in Los Angeles, San Diego, and Chicago. A friend of mine in LA who frequents one of these places was tested as a result. She was in “sushi detox” when we last had dinner together. Later we learned she was trying to get pregnant, and she tested for mercury as a precaution.


Sushi fans, beware. What these studies have found is disturbing. More than 10% of tuna samples contain levels of mercury that shouldn’t be eaten by any consumer–man, woman, or child–because they exceed the FDA’s “actionable level” of mercury (1.0 ppm). Nearly 70% of sushi tuna samples collected exceed Illinois EPA’s special advisory threshold.

If you figure sushi chefs charging $25.00 a piece are more discriminating about their choice of fish than those charging $2.50, then the average consumer should be very concerned about tuna. I used the “Mercury calculator” at GotMercury’s website to learn that 6 oz. a week of my favorite albacore tuna brings me to 100% exposure.

Some canned tuna is also contaminated. Albacore tuna contains 3 times the mercury of chunk light (0.353 ppm vs. 0.118 ppm). However, cans of chunk light tuna usually contain skipjack tuna, a smaller species with lower average mercury levels. A Chicago Tribune investigation found that chunk-light canned tuna sometimes contains yellowfin tuna (0.325 ppm), but the cans are not labeled correctly. Know your tuna! Read the label before you buy.

Peter Etnoyer (406 Posts)

PhD candidate at Texas A&M University- Corpus Christi and doctoral fellow Harte Research Institute for Gulf of Mexico Studies.





24 comments on “How safe is your sushi?
  1. Um … guys, you really need to understand a bit more about toxicology before you go overboard with this mercury scare. Most of what the Chicago Tribune printed has been refuted widely now, and the “Got Mercury” website fails to account for a ten-fold safety cushion in the government’s mercury limits. I’ve looked at these sushi surveys, and not a single one of them found any fish that’s actually dangerous. Considering the ten-fold safety margin, they basically found some fish whose mercury content was ten percent of what might be harmful. Ask yourself why the medical literature contains zero cases of fish-related mercury poisoning in North America. And why the Japanese live so long.

  2. Where’s the study attributing Japanese longevity to mercury? Japanese have a low fat diet with little milk or cheese, but atherosclerosis is still a leading cause of death.

    One in ten pieces of sushi in Chicago were “actionable” by EPA and FDA standards, so according to those organizations (and your doctor), there is a problem with the mercury content in metropolitan tuna sushi.

  3. Um … no. The FDA Action Level is set at one-tenth the actual danger level. When was the last time the federal government did anything right? If my doctor couldn’t distinguish between the federal government’s advice and good science, I’d get a new doctor.

    And the Japanese population’s longevity has in fact been scientifically linked to their massive intake of Omega-3 fats, which are very plentiful in fish. And Harvard studies show conclusively that hypothetical health risks from mercury are a non-issue compared to the proven health benefits of Omega-3 fats.

    Seriously … you’re doing some serious public-health malpractice here. Please reconsider what you’re saying before you start scaring people away from fish. It’s a health food, for crying out loud.

  4. Every pregnant woman I’ve known, and I know quite a few, have been advised against smoking, drinking alcohol and eating fish that are known to have a high level of mercury. Are you saying that these doctors don’t know good science?
    If it is a health food, how come pregnant women are told to restrict their consumption?

  5. Does this study apply to sushi in Japan too? I will be going to Japan next Wednesday and Im pretty sure I will be eating sushi a couple times while I’m there. However my friends always complain about the sushi here and say it doesn’t taste the same as back home so maybe there is a difference.

  6. Doctors advise pregnant women to steer clear of some fish because they overreact to the EPA’s advisories — which are themselves overreactions to a few cherry-picked studies. It’s funny … if you look at the scientific literature, you’ll find a massive study published in The Lancet this year. It’s the biggest study of its kind, ever. Government-funded. And it concluded that pregnant women who eat the most fish give birth to the kids with the highest IQ and developmental scores. The point isn’t that mercury is good for you. It’s that what’s good in fish is far more powerful than what’s not so good. And developing fetuses need Omega-3s.

  7. First off, concern for our sushi should be as much over the issue of resource scarcity as it is human health.

    Secondly, the comment that seafood “is a health food, for crying out loud” is generalizing to the point of sounding inane.In the U.S., it is estimated that seafood products cause 18 to 20 percent of the food borne illnesses contracted by 76 million Americans each year.

    In an upcoming publication on seafood mislabeling, I elucidate some instances of seafood (particularly mislabeled products) affecting human health. Here are a few:

    Two Chicago consumers of recently fell ill after ingesting the tetrodotoxin found in pufferfish, which was mislabeled as

  8. Ok so Tuna has Mercury, whether potentially deadly or not you should limit your intake. Now trying to say “stay away from fish” will kill more people than help. I say this because it is in fact good for you. In general, if you are buying your fish fresh you should be able to tell what you are buying by looking at it. Also, looking at the study parameters, they studied 700 fish and made generalizations across the entire world? 700 fish is NOTHING. What a small sample size! Plus everyone already knows that wild salmon are better than farm raised so good job in beating a dead horse.

    Pretty much I would say two things:
    1) 2/3 of this information was already known by the general public
    2) The “deadly fish” is about as hyped-up as you should never eat raw eggs. (This by the way is FALSE. Only 1 in every 30,000 eggs is tainted and they only come from sick chicken kept in pens)

  9. Only 1 in every 30,000 eggs is tainted and they only come from sick chicken kept in pens

    Which is another thing the Japanese eat. I was served a raw egg at the first dinner visiting my in-laws (Japanese). It was used as a sort of dipping sauce for the sukiyaki. My western-bred fear of raw eggs didn’t let me try it and that was embarassing.

  10. Does anyone who reads a newspaper believe that the EPA and FDA, under the Bush Administration, are leaning too far toward protecting human health rather than protecting corporate interests… fooling MDs into “overreacting” when advising their patients about seafood consumption?

    Big Tuna has a whole PR firm hired to confuse the public about the impacts of mercury from tainted seafood, so there is no surprise to see some of the comments here questioning the EPA standards, which are less starict than those found in Europe.

    Avoiding large, long-living predatroy fish (especially swordfish, tuna, shark and king mackerel), which bioaccumulate mercury, is good for your heatlh and good for the oceans.

  11. “Plus everyone already knows that wild salmon are better than farm raised so good job in beating a dead horse.”

    -which explains why most of the “wild” salmon in restaurants and in stores turns out to actually be farm raised. Mendacity wins again.

  12. Greg never said that the Japanese live so long because of exposure to mercury.

    nice silly strawman

  13. Greg also never said that 800+ people in Japan suffered disease of the central nervous system in the famous Minimata Disaster, wherein 27 tons of mercury were dumped into Minamata Bay by Chisso Corporation between 1932-1978.

    Human symptoms included numbness in the limbs, invountary movements, uncontollable shouting, blurred vision, and unconsciousness.

    The link between high levels of mercury and CNS damage is clear in the Japanese courts. Some of the Minimata cases were still in court in the early 90′s, but apparently the “disaster” subsided when mercury dumping ceased.

  14. Come on, guys — Minamata was caused by an industrial spill, not ambient mercury levels in ordinary fish. The levels measured in Minamata were dozens of times greater than what we see in garden-variety fish. Using Minamata to justify a fish scare in the rest of the world (or even in the rest of Japan) would be like arguing to ban organic spinach because of the recent E.Coli outbreak in California.

    Again, I’ll finish where I started. You need a more sophisticated understanding of toxicology. The dose makes the poison. Too much of anything — including water — will kill you. But oxygen toxicity, like Minamata disease, is so rare that we don’t stop breathing or drinking H2O.

    I’m done with this topic. I hope I was able to bring some sanity to this discussion — Lord knows it needed some — but I have other dragons to slay.

    Peace.

  15. Hi, I’m new to the blog. I saw the headline and clicked over because I live in Japan and eat sushi about four or five times a month (which is actually more than the average Japanese person). I must say that these studies do sound like simple fear-mongering, and Mr. Etoyner is either bad at reading or simply likes to offer up strawmen for fun. What Mr. Cartwright is saying is much more reasonable, and if you’ll take a minute to read what he has written he doesn’t claim that mercury is good for anyone, he simply points out the obvious fact that it’s not as bad as everyone is making it out to be…and the levels are so low it couldn’t possibly matter unless you were consuming pounds of raw fish every week. And I can assure you, no one in Japan ever eats that much sushi. It’s meant to be a snack, not a meal.

    Now as for decimation of fish populations…that’s a different story. Sushi…and fish consumption in general in Japan…are huge culprits in that ecological disaster.

  16. Obviously the safe limit of any substance for a fully grown, healthy adult is exactly the same as for a developing embryo, even if it is a known mutanogen.

    [/snark]

    Anyways, with the collapse of the fisheries this won’t be a problem much longer.

  17. Okay — One parting shot just to satisfy that last “snark” … Whether you’re talking about a fully grown adult or a fetus, you measure concentration of toxins, not amounts. It’s typically done as a ratio (nanograms of toxins per deciliter of blood). So, yes, the applicable ratio is constant, regardless of age.

  18. Surely this is taking a step too far? Sushi is considered as one of the most healthy meals on the planet, hence the longevity of the Japanese population. Maybe there are mercury levels in the fish, but it’s not as deadly as such studies make them out to be… surely? How can it explain the long lives lived by the Japanese people?

    As for other countries… statistics show that many many more people die from other dietary problems such as high saturated fats… who’s ever heard of a death from eating too much sushi? (Well… except perhaps the blowfish, but that’s due to another reason…)

  19. I think several people have gone off on tangents or have extrapolated the main argument too far. The original article by Peter said that the concentration of mercury in tuna being served at U.S. restaurants exceeded federal standards and the more stringent standards of the state of Illinois. Whether you agree with the standards is a separate question.

    ppm is a concentration defined as 1 particle of a given substance for every 999,999 other particles. Therefore, 0.325 particles of mercury per all particle analyzed standardized to a million.

    Yes, fish as a whole are very healthy for you. Not every fish is tainted with mercury. Long-lived, predatory fish tend to bioaccumulate more mercury over time. Therefore, you are better off consuming less. Yes, your body can deal with low doses of mercury, but the point of this blog article is to educate yourself to reduce your own risk of bioaccumulating mercury.

    I love seafood and sushi and will continue eating it, but I certainly limit mine and my family’s consumption to safe amounts. Tuna is also only one type of sushi. The majority of sushi is something else (oh delicious spider maki and eel… you tempt me so.)

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  21. Title is misleading. It should be ‘How Safe is Tuna’
    You can have other sushi without mercury risk.

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