Extracting/Disposing of Methyl Mercury (methylmercury) from Canned Tuna

December 22, 2012 2:14 AM

How can I extract/rid of methylmercury out of canned Tuna? I bought a ton, and just realized I should have went with canned salmon. There HAS to be an easy way to at least cut down on the Hg content... right?

There's got to a be a natural way to reduce (if not abolish) the methylmercury (ions of mercury with some other thing?) found in tuna...

Things I found online:

It boils off just under 200 degrees F. That would destroy the nutrient
This is methylmercury... not mercury... is the mercury carried away at 200 degrees? Or is only part of it evaporated? It's not water soluble... Could I just turn the pan up near 300deg and slap the tuna on for 9 seconds and swish her round?

Also.... would the following information suggest that the sulfur-thiols that onions release: http://tinyurl.com/btky2pb

Would react quite well with methylmercury: http://en.wikipedia.org/wiki/Methylmercury#Structure

I don't know where to go with this knowledge. I'm sure there are lots other variables I have not taken into account.
ANY criticism and any advice is greatly appreciatted. I truly do feel there is a simple way to deal with the mercury. I'd much rather extract it out somehow, though, rather than treat it while it's in my system with cholerra or selenium. Maybe I'll combine both methods.

Regardless, any help out there? I'm sure if a simple solution is put together, it will help millions!

I just don't wanna waste that tuna, and I don't mind learning anything!

So far, I'm thinking I could just mix it with lots of various thiol-containing veggies, cut it up, and sautee the whole thing and eat whatever comes out.

Any other ideas?!?!

posted by JamesBlakeAV to health & fitness (26 answers total)

Could I turn the oven to 300 and let it sit in there for a few minutes?
posted by JamesBlakeAV at 2:15 AM on December 22, 2012

You have zero chance of removing any specific chemical from your tuna without destroying it, or at the very least rendering it down to unpalatable mush.

Eat it, give it away, throw it away: those are your three options.
posted by pipeski at 2:22 AM on December 22, 2012 [10 favorites]

I work in seafood, and I do not understand your question.

I think your worst fear is radiation from Fukishima - not heavy metals.

Tuna is a large and long lived fish - it picks up a lot of toxins. That is a fact.
posted by jbenben at 2:27 AM on December 22, 2012 [4 favorites]

My question, more simply put, is what are some methods on how to rid of toxins found in tuna!

And I see! Looks like I'll be buying salmon. Guess I'll use the tuna as bait meat for zombies :P
posted by JamesBlakeAV at 2:37 AM on December 22, 2012

You could feed it to a cat. Preferably one not to enamored of its higher-thinking skills.
posted by kaibutsu at 2:39 AM on December 22, 2012 [4 favorites]

The best answer, IMO, is to enjoy the tuna. Then eat something else for a while.

Here is what the Whole Foods website has to say:

"Since canned light tuna is processed from smaller varieties of tuna, it will have less mercury than either canned albacore (white) tuna or tuna steaks/fillets. Accordingly, the FDA and EPA advise limiting intake of both albacore tuna and tuna steaks/fillets to up to 6 ounces (one average meal) of tuna steak eaten per week."
posted by megatherium at 2:39 AM on December 22, 2012 [3 favorites]

Quoting pipeski:

"You have zero chance of removing any specific chemical from your tuna without destroying it, or at the very least rendering it down to unpalatable mush.

Eat it, give it away, throw it away: those are your three options."

End quote.

Well... I'm okay with an unpaletable mush. I can put it in soup or something creative. I already knew my most basic options. There are many other options I could choose... like gathering it all up on one big bag then feed the ravens, until I form a large following of birds. Not sure what that's useful for, youtube video maybe?
posted by JamesBlakeAV at 2:40 AM on December 22, 2012

Eh... Looks like I'm on my own on this one. For anyone that is serious about the matter, shoot me an email at [e-mail]. Other than that, I'll probably check back in a day or so.
posted by JamesBlakeAV at 2:43 AM on December 22, 2012

I do not believe there is a practical way to do what you want.
posted by ryanrs at 3:09 AM on December 22, 2012 [1 favorite]

[JamesBlakeAV, moderator here. You need to relax a bit with the commenting and just ignore the answers that don't interest you. Maybe you'll get some interesting and/or helpful info, or maybe not, but not every question is answered in less than a half-hour, nor is every question even answerable in exactly the way the original poster hopes. Patience.]
posted by taz at 3:09 AM on December 22, 2012 [2 favorites]

The only thing worse than organomecury compounds in your food is organomercury compounds in your breathing air. You actually absorb mercury far more efficiently through your lungs than you do through your GI tract. So even if it's true that methylmecury boils off a certain point... well, let's just say that you might not want to be in the room when that happens.

The simplest answer is, of course, to not eat any fish that concerns you. There are plenty of fish in the sea (har) that have lower levels of mecury. But if you are set on doing this, thio-containing veggies aren't gonna cut it. One issue is the degree of reactivity, the other is surface area and the availability of reactive bind sites. Also, were you planning on eating these veggies afterwards? Cause that seems like a bad idea.

To really get the job done, you'll need to fully homogenize the tuna to a liquid and mix it thoroughly with a chelating agent, such as dimercaprol, dimercaptosuccinic acid, or dimercapto-propane sulfonate. Ideally, afterwards, you would need chemically separate the chelated metals from the rest of the tuna slurry. You do have a basic HPLC set-up at home, right?
posted by dephlogisticated at 3:27 AM on December 22, 2012 [27 favorites]

Assuming you could somehow evaporate the mercury in your tuna... you would now be inhaling it as it cooks rather than digesting it. I don't think either of those is a good option.

As far as chelation... I'd note that the FDA has not approved a safe method for chelating methylmercury. Just because a vegtable contains some compound that contains a thiol group doesn't mean that that thiol group is free, willing, or ready to bond to the methylmercury.

There is no easy way to remove the mercury from fish. Your intuition has lead you astray. If it were easy, people would be doing it rather than just accept the risk or limiting their intake.
posted by sbutler at 3:27 AM on December 22, 2012 [3 favorites]

Thanks everyone :) Learned a lot tonight!
And maybe my intuition subconsciously was just trying to get me to eat more veggies, lol.

<3
posted by JamesBlakeAV at 5:13 AM on December 22, 2012

I don't understand why you don't just eat your canned tuna occasionally, once a week or less, until it is gone. The danger of mercury in tuna, as I understand it, is only considerable when tuna is consumed too frequently or in too great an amount.
posted by General Tonic at 7:31 AM on December 22, 2012 [6 favorites]

You could feed it to a cat. Preferably one not to enamored of its higher-thinking skills.

A side note: don't feed it to a cat, at least not for more than an occasional treat. Tuna, particularly canned tuna, lacks several important vitamins and minerals, and eating a lot of it can cause problems for cats.
posted by jedicus at 8:27 AM on December 22, 2012 [2 favorites]

You could donate it to your local food bank and then take a write-off on your taxes?
posted by amanda at 8:51 AM on December 22, 2012 [2 favorites]

My supermarket takes returns of unopened food in its original condition. Call the place where you bought it and see if you can return it or exchange it for food you feel comfortable eating.
posted by decathecting at 8:58 AM on December 22, 2012 [2 favorites]

Dephlogisticated's answer, while facetious (I chuckled, anyway) is correct. The procedure you are asking about is one that could be done in a suitably-equipped laboratory (albeit the tuna would be a gross slime afterwards) but not in a kitchen.

Also, to emphasize what others in this thread have said, it's all a matter of dosage. Methylmercury is quite toxic indeed and if canned tuna was a major staple of your diet or if you were pregnant or a young child, then you might have cause for concern. However, you are vanishingly unlikely to build up a toxic dose of mercury in your system just by eating a whole bunch of tuna over a short period of time. The kind of dosages required in order to make you sick need to build up over time through continual consumption -- there is not enough methylmercury in tuna to harm you from any one exposure event.

For your research (since this is obviously a matter of some concern to you, which is reasonable enough) here are some of the USDA's pages on methylmercury in fish:

What You Need to Know About Mercury in Fish and Shellfish (key quotes: "For most people, the risk from mercury by eating fish and shellfish is not a health concern" and especially "Eat up to 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury. Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, pollock, and catfish. Another commonly eaten fish, albacore ("white") tuna has more mercury than canned light tuna. So, when choosing your two meals of fish and shellfish, you may eat up to 6 ounces (one average meal) of albacore tuna per week.")

Mercury Levels in Commercial Fish and Shellfish (You want to look at the mean mercury concentration for a given species here, i.e. the first two columns of the table. Note that canned tuna, depending on whether it's "light" or "albacore" tuna, has either low or moderate concentrations of mercury as far as the USDA is concerned. Higher than salmon, but not nearly so high as the high-mercury fishes like swordfish. The USDA recommends 12 oz per week of canned light tuna or 6 oz per week of albacore, per the previous document.)

Public Health Statement for Mercury (This is not fish-specific, but rather is a summary of the extensive body of peer-reviewed research involving mercury toxicity in general -- dosages, modes of exposure, effects, etc. You can find a fair bit of information on mercury in fish in section 1.3, "How Might I Be Exposed to Mercury?")

Your concerns are reasonable but the best thing to do is just to limit your consumption. The USDA recommends 12 oz of light tuna or 6 oz of albacore tuna per week, and if you want to be cautious (because hey, who trusts the USDA these days anyway?) perhaps you could reasonably cut that down a bit and go with 6 oz of light tuna per week and 3 oz of albacore per week (or 6 oz every other week, which works out the same as mercury poisoning is about dosage over time).

For a more cautious perspective than the USDA you might try Consumer Reports (an independent, non-profit consumer-advocate organization which conducts its own extensive testing on a great many things including food) with their article Mercury in Canned Tuna Still a Concern, which notes that in their testing they found occasional cans of tuna with higher mercury content which the USDA does not explicitly include in their official reports. They do note however that the USDA informed them that those outliers were accounted for when the consumption guidelines were created. Their bottom line: "Canned tuna, especially white, tends to be high in mercury, and younger women and children should limit how much they eat. As a precaution, pregnant women should avoid tuna entirely." They mention nothing about healthy non-pregnant adults, so one might assume that it remains safe to consume moderate amounts of canned tuna if one is a healthy non-pregnant adult.

I hope that helps. It's always good to be as informed as possible about these things, and I think that the information in the links above is the closest thing to the Capital-T Truth as any member of the public can get (and hence the best thing to base one's actions on). If you are still concerned then you should not feel crazy by being a bit cautious and eating less than the recommended allowance, but I think you can feel perfectly safe in slowly eating your way through the tuna you have bought. It's not like it's going to go bad on you, as it's canned.

I hope this helped you!
posted by Scientist at 9:10 AM on December 22, 2012 [13 favorites]

Ok, I think the real problem here isn't the mercury, it's that you are under the impression that pureed boiled tuna could be used in a soup.

Feed it to a cat.
posted by oceanjesse at 9:14 AM on December 22, 2012 [4 favorites]

Feed it to a cat

As a treat, in small portions. Tuna lacks nutrients vital to a healthy cat, and the animal will likely develop steatis, a painful inflammation of the subcutaneous fat caused by Vitamin E deficiency, if fed only tuna for an extended period of time. No more than 5-10% of your cat's food should be table food.
posted by kindall at 9:50 AM on December 22, 2012 [1 favorite]

Seconding amanda, please please, if you are not going to eat or return this tuna to the supermarket, donate it to your local food bank. As Scientist outlined above, occasional tuna consumption is not harmful, so don't feel like you're poisoning anyone - food banks are generally very happy to get donations of protein-rich foods.

As to your question, I think the flaw in your reasoning is that if there *did* exist a cheap, easy, safe way to remove mercury from tuna, don't you think the tuna processors would already be doing so? Even if they weren't required to by regulations, I'm sure you could charge a significant markup and make a mint by marketing your tuna as 'mercury-free'. The fact that this is not already on offer tells you that doing so is not economically or chemically feasible.
posted by aiglet at 10:28 AM on December 22, 2012 [1 favorite]

:D SO MANY RESPONSES Thank you everyone loved reading through them :)

As to the last response:

"As to your question, I think the flaw in your reasoning is that if there *did* exist a cheap, easy, safe way to remove mercury from tuna, don't you think the tuna processors would already be doing so?"

Well... I don't think everyone quite knows the answer to everything yet, so no, I don't think the best/easiest way to do anything specific has been discovered yet. No matter which directions humans look (outward towards space or inwards with microscopes), more questions arise. What is economically or chemically feasible is only limited if one limits themselves.

Someone close to me always told me my reasonings were flawed, because if there was a better way, it'd be done already. To me, that's the first step one would need to talk to never achieving anything of great worth to mankind. Apart from accidental discoveries, I suppose.

Everything is a remix. Who will remix it the best, though? Regardless, I live life constantly poking and prodding for answers. Failure or being wrong is part of the game. And provides a good experience on how or on what to improve the next time around.

Everyone can be a game-changer. Better than being the regular player, imho.
posted by JamesBlakeAV at 7:41 PM on December 22, 2012

And I won't feed my cat mercury! I love him! I'll get him Salmon haha
posted by JamesBlakeAV at 7:43 PM on December 22, 2012

One other thing to keep in mind is that the hatters (to which the phrase "mad as a hatter" pertain) worked with mercury closely for years before getting to the really overt poisoning stage. This isn't to minimize the danger of mercury (or lead, or other heavy metals) but is to point out that your body (unless compromised in some way) can handle a bit of whatever you throw at it. You should be able to slowly eat the tuna, following the recommendations posted above. Else, donate it to a food bank, they'll be glad to have it.
posted by RogueTech at 4:33 AM on December 23, 2012 [1 favorite]

Your canned tuna was already heated for hours before and after it was put in the can.

Also this is just speculation, but if there was a simple solution to remove toxins from tuna I imagine the companies producing canned tuna would be doing it. It would be a way to convince consumers to buy more tuna.
posted by inertia at 6:36 AM on December 24, 2012 [1 favorite]

Thanks every one, you are all so great :)!
posted by JamesBlakeAV at 12:35 AM on January 30