Mercury in fish--what do we need to know?

Yesterday I wrote a story for the paper about how conservation group Oceana released a study that revealed much higher levels of mercury in tuna than the FDA had previously estimated. A study conducted by the New York Times revealed similar findings. For fish-eaters seeking guidance, here’s the skinny:

Q: How does mercury get in fish?
A: Mercury pollution comes from numerous sources like coal-fired power plants and incinerators. In addition to the combustion of fossil fuels, which creates mercury vapor, mercury pollution may come from unlikely sources like the dental industry. Dental amalgams are 49 percent mercury by weight, some of which leaks into our water system.

According to the Monterey Bay Aquarium’s Seafood Watch, bacteria in water transform mercury into methylmercury. Smaller bottom feeders absorb the methylmercury, which they then pass up the food chain in higher concentrations. Top-level carnivores like tuna and swordfish have the highest likelihood of containing harmful amounts of manmade chemicals, stored in their muscles and fatty tissue. These larger, longer-lived species have more time to accumulate dangerous levels of methylmercury.

While mercury is the second most toxic substance known to man (the first being uranium), methylmercury is more damaging than inorganic mercury because it is more easily assimilated into the body.

Q:  What does methylmercury do?
A: According to the FDA, exposure to high levels of methylmercury can harm an unborn baby’s developing nervous system (brain and spinal cord). Young children exposed to high doses of mercury while in the womb or after birth are at risk for limited attention span; poor language, visual-spatial, memory and coordination skills; as well as lower IQ. But adults are at risk as well. Mercury poisoning victims have experienced nervous system effects such as loss of coordination, blurred vision or blindness, and hearing and speech impairment.

Q: Who should be concerned about mercury?
A: In 2004, the Environmental Protection Agency and the FDA formally advised women of childbearing age and young children that they could safely eat up to 12 ounces of low-mercury seafood per week. But according to Dr. Rashid Buttar, head of the Charlotte, NC-based Center for Advanced Medicine and Clinical Research and Chairman of the American Board of Clinical Metal Toxicology, there are other groups that are at risk.

“Anyone who is immunocompromised--diabetics, patients who have gone through a transplant, cancer patients, HIV patients, and anyone over the age of 70 and under the age of 7—should avoid high-mercury fish. Mercury is a very significant immunosuppressive agent. We also find that there are certain genetic predispositions that people have that make them unable to excrete mercury or other metals efficiently. We find that children with developmental delays or people with Alzheimer’s can’t get rid of it.”

Q: Which kinds of fish are OK?
A: Dr Buttar suggests avoiding all big game fish (tuna, swordfish, marlin, etc.). He suggests eating deep ocean fish (cod, for instance) and smaller to midsize fish like tilapia. “Fish from the Gulf of Mexico is more worrisome than fish from the open ocean. In the Gulf there’s more drainage from land masses.” For people eager to maximize the benefits of omega-3 fatty acids but minimize their mercury risk, he suggests wild salmon from Alaska (“not domesticated farm-raised which, because of its feed, has a low omega-3 fatty acid profile”).

Q: But what if I only eat a little—is it safe to eat ahi once a week?
A: “How much high-mercury fish is safe? None, as far as I’m concerned,” says Dr. Buttar. “There’s no safe level of mercury. Mercury levels should be aggressively monitored and documented by the FDA.”

Comments

[concerned citizen]

I want to know why Publix is not setting out FDA warnings so consumers can make better decisions at point of purchase.

They are putting people's health at stake just to make a sale.

Shameful!

[Steve]

Please check the info on the amalgams. My dentist told me the mercury content is very low these days compared to 30 years ago.

[Chris]

There are many sources of natural mercury- there's no proof that any of the mercury in fish is due to human activity.

Chris,
We are talking about the way mercury converts to a form that is taken up by the food wed and poses a health threat to pregnant women, children, and others with compromised immune systems. That is certainly triggered by the human activities of burning coal- which releases mercury into the atmosphere and eventually onto our dinner plates when we eat tuna and swordfish.

Save your repugnant talking points for your uninformed global warming arguments. You that proud to be ignorant?

I agree with the first post. Publix needs to do the right thing, and that is to be responsible and post FDA warnings. Expecting consumers to do their own research on toxic fish is like selling toxic toys to the public, and expecting parents to find out on their own which ones will poison or choke their children.

[The Mouth]

I wonder how much your average grocery store would lose in total revenues if it had a single chart affixed to its seafood counter with a nutritional and health-risk breakdowns for common species of fish. If someone wants a nice piece of fish for dinner, but are told that maybe the ahi isn't a wise choice, are they going to go grab a pound of hamburger instead? I doubt it--they'll refocus on wild salmon, or snapper, etc.

[hg]

To: “Save your repugnant talking points…”
You need to back off the name calling/emotion and do a little research yourself. Mercury content of large fish has been consistently high for over 200 years (and likely much longer but samples are sparse) and the obvious and primary factor is undersea volcanic activity. The recent finding in tuna is not news. This study does not look at older samples. Prior studies have taken samples from mounted fish and lobster from museums. I’m not saying Mercury is benign, just saying there is more to the story.

[The Urban Eater]

Hmmm. I'm a little torn on this one. I am a Personal Chef and one of my weekly clients requests tuna every week. The rest of the menu is other seafood. I've been cooking for them for over 8 months and they recently had the annual family check up, blood work included. Their doctor was shocked at how great their tests came back. I have to wonder if this is a false fear.
I'm not disagreeing with science, but I'm not agreeing either.

[Allan]

Actually not all pelagic gamefish are as bad. Fast growing but short lived species such as Mahi Mahi or Wahoo do not live long enough to accumulate the same quantities of mercury in their tissues as do tuna, swordfish, or sharks. The FWC continually monitors mercury content in fish caught locally in Tampa Bay.

Another "scientist" trying to make a name for himself using scare tactics.