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It is toxic to everything as far as I’m aware. The major danger of the bio accumulation idea is that the higher up in the food chain an organism is the more it will accumulate those toxins and die. So for example a plankton might have only a few molecules of mercury in it, but then zooplankton eats 20 of those so it has 20x the mercury in it. Then a fish eats 20 of those and so it has 400x the mercury in a plankton. And so if a human eats fish five times a week that human is potentially eating lots of mercury, and that mercury isn’t ever excreted by the body.

Mercury is excreted by the kidney, the half-life of methylmercury in the blood is ~70 days

Yep, this is the right idea. This is why eating predators like Tuna is worse than eating seafood lower on the food chain.

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Yup, and humans are large, live extremely long lives (more time to accumulate), and are exist at the top-iest of the top of the food chain.

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So it actually will filter out, it just takes a stupidly long time and does damage while in there?

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The idea of bioaccumulation is that you intake more than you excrete, so it builds up.

Mercury seems to affect the nervous system mainly. It is my understanding that most neurons are not regenerated, and recovery is usually slow and incomplete.

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But being larger creatures does that mean we can reasonably take in a larger dose of mercury and be relatively okay from it?

So (predatory) fish are also affected by mercury, and die when they have too much accumulated? If there is less mercury in the air and in the ocean, fish (and those of us who like to eat fish) could live longer?

yes, but that's countered by living long meaning you can take up way more, than an organism that e.g. is larger but lives shorter.

Ah so we can ingest more but because it sticks around so long and we live so long it doesn't really matter?

Not sure about tuna specifically, since that's a fairly large fish, but the nutritional benefits of regularly eating fish typically outweigh the harm IIRC.

I wouldn't say it doesn't matter. It is still a significant factor.

For example, a similar concept applies when prescribing medication. Overweight people have larger volumes and thus, depending on meds, need more to reach the same effect.

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Quite the opposite. Humans are high in mercury. Except for vegetarians. Feel free to eat vegetarians.

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But thanks for the tip, I already was for the low fat content.

Why not be sure before commenting? Bioaccumulation in large predators like tuna is a big problem, as the commenter stated. The benefits (general wellbeing) does not outweigh risks (paralysis and death) of a high-tuna diet. A mercury-consious fish diet can be healthy tho.

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The problem is not fish dying from mercury poisoning (I mean, that would be a problem, a really big one). Much before the levels required for that, the fish may have for example brain damage, which is not such a big deal for fish, but an equivalent in humans render you invalid to carry out a normal life.

Yes, but it also means we need to eat more.

Take two animals with identical metabolisms, one's 10kg and one's 100kg.

If both eat 0.1mg per day of a toxin, then yeah, the bigger creature will do better.

But if the food contains 0.1 mg/kg of food, and the big creature needs to eat 10x more food to survive, then it balances out.

Brain damage would be an issue for any animal. Predators not being able to hunt and track their prey, which would represent most of their brain power, or prey not being able to evade strikes.

You're correct, I should have been sure before commenting.

The intention of my comment was that, although seafood contains a non-insignificant amount of mercury (and other toxins), one should not be afraid of eating fish regularly.

The most recent study I could find found no evidence of developmental harm among children with high seafood diet mothers.

Sort of. Part of the reason that antibiotics work so well is that the amount to kill a bacterium is way smaller than the amount to kill a person.

The problem with mercury (and heavy metals in general) is that there's no way to flush them from the body.* We don't usually worry about salt buildup, because our bodies naturally dilute the salt and flush it out the kidneys. Things like that don't happen with the heavy metals.

* Yes, chelation therapy exists as a treatment for heavy metal poisoning. There are pretty strict guidelines, mostly because one of the side effects of chelation therapy can be death. "The therapy was a success but the patient died."

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While large animals eat more, they also eat foods that themselves have higher concentrations of mercury.

Krill eat mercury, have tiny amounts of mercury. Small fish eats many krill, bioaccumulate all the mercury from the krill. Small fish has relatively much more mercury in them than krill.

Medium fish eats many small fish. Medium fish bioaccumulates mercury from many small fish, it has even higher concentrations of mercury.

Large fish eats medium fish.

We eat the large fish, which has A LOT of mercury in it. Many times more mercury than the small animals do.

So it's not just the matter of we need more mercury and we eat more mercury but we tend to eat animals which themselves have relatively high levels of mercury. Then live long lives, giving said mercury a lot of time to build up.

I guess it's a bit redundant with the top of the food chain line.

Uh, as a sterile man, my concerns over mercury poisoning isn't toward my future babies, but my current brain.

The opposite. Because we live so long, we have more chances to absorb mercury than short-lived animals, which is worse for us. Obviously living longer is itself usually a preferred state, but it does cause situations like this where health issues arise over long periods of time.