Methylmercury in Fish: The Facts

[Guest guest]

Fish in news. We know healthy fish healthy for us. But which to choose?

Help make right choice:

Do you eat tuna or any other fish? If you do, read this:

Methylmercury in Fish: The Facts

by Anne Gallo, M.S. and Madeleine Levin, MPH

What is methylmercury?

Mercury is a mineral that exists naturally in the environment. In

addition, thousands of tons are released into the air each year

through pollution and waste. Bacteria and natural processes can

transform mercury into the organic mercury compound methylmercury

(MeHg), which is a poisonous substance.

Unfortunately, this toxin is in the fish we eat. Methylmercury can

enter the water or soil, accumulating in streams and oceans. It also

accumulates in the food chain, as each fish absorbs all the mercury of

the smaller fish or organisms it has eaten. That is why the oldest and

largest fish, such as shark and swordfish, tend to have the highest

levels. Methylmercury levels are higher in people who regularly eat fish.

Who is at risk?

The developing fetus is at greatest risk, when a pregnant mother eats

a lot of fish. Methylmercury easily crosses the placenta, and

accumulates in an unborn baby's blood. A baby's developing brain and

nervous system are very sensitive to this toxin, and remain vulnerable

after birth. Newborns can also consume methylmercury through breast

milk. Young children who eat fish may also be at risk because,

compared to adults, they eat more food relative to their body size.

The Center For Disease Control and Prevention (CDC) defines

populations sensitive to mercury exposure as pregnant and nursing

women, children under the age of six (especially up to the age of

three), people with impaired kidney function, and those with very

sensitive immune responses to metals.

Which fish are harmful?

There is limited information about methylmercury in fish because there

is no national or statewide system in place to monitor amounts. Most

states, Native American tribes, and U.S. Territories issue advisories

that warn people when they are aware of methylmercury contamination.

The advisories indicate what types, size, and amounts of fish are of

concern. Pollution can result in high mercury levels in fish.

Otherwise, methylmercury levels for most fish are relatively low,

ranging from less than .01 part per million (ppm) to .5 ppm.

A few fish are so high in methylmercury that they should be totally

avoided by pregnant or nursing women, young children, and other

at-risk populations. (Please see chart below.) In March 2004, the Food

and Drug Administration (FDA) and the Environmental Protection Agency

(EPA) issued a joint Consumer Advisory warning about methylmercury in

fish. The advisory continues a previous warning against 4 particular

species of fish and for the first time includes a specific warning

about the consumption of tuna.

The advisory recommends that women who might become pregnant, who are

pregnant or nursing and young children do the following:

* Avoid eating these four species of fish: shark, swordfish, king

mackerel, and tilefish (also known as golden bass or golden snapper);

* Limit their consumption of all other types of fish to 12 oz per

week;

* Limit their consumption of canned albacore ( " white " ) tuna or

fresh tuna to no more than 6 ounces per week;

* Limit the fish eaten by young children to even smaller portions

per week (no specific advice is given);

* Check local advisories about the safety of fish caught in local

lakes, rivers, and coastal areas. If no advice is available, eat no

more than 6 ounces per week of locally caught fish, and do not consume

any other fish during that week;

* If more than the recommended amount of fish is eaten in one

week, eat less in the following weeks.

The previous advice given by the EPA was more cautious, but they

compromised with the FDA's less cautious approach. The EPA calculated

safe levels of methylmercury based on individual bodyweight. Based on

that previous standard, 6 ounces of canned albacore white tuna or

fresh tuna per week could expose a pregnant or nursing woman to too

much mercury, especially if she ate other fish as well. Many experts

and consumer groups recommend caution by using the earlier EPA

standards instead of the current joint advisory.

Concerns about Tuna

Levels of methylmercury in tuna are lower than in the four fish on the

" do not eat " list but higher than many other fish. Since Americans eat

so much tuna the risk could be greater. There are two types of canned

tuna generally found in the U.S. market - albacore white and " light. "

Fresh tuna and canned albacore white tuna are three times as high in

methylmercury as canned light tuna, which comes from smaller fish. The

amount of mercury in canned tuna varies from can to can, with canned

albacore white tuna sometimes exceeding the danger zone of 1 part per

million.

While tuna is high in omega 3 acids, low in saturated fat, and high in

protein and vitamin E, and can therefore be a part of a healthy diet,

we recommend that women who may become pregnant, pregnant women and

nursing mothers avoid fresh tuna and canned albacore white tuna and

eat no more than one 6 ounce can of light tuna per week. (For most

women, that would be two or three tuna salad sandwiches, depending on

what the tuna salad contains). If a woman in these high-risk

categories does have tuna steak, tuna sushi, or canned albacore white

tuna, we recommend that she reduce her intake of fish over the next

weeks to reduce her mercury intake. We recommend that young children

consume no fresh tuna or canned albacore tuna, and less than 6 ounces

per week of canned light tuna or other fish with moderate mercury

levels. It is possible that more could result in neurological damage

to babies and young children.

The risks

The health risks of methylmercury include paraesthesia (a pricking,

tingling or creeping sensation on the skin), depression, and blurred

vision. Research also suggests neurobehavioral effects on fetuses and

developing infants, including attention span, language, visual-spatial

skills, memory, and coordination. Several years ago, the National

Academy of Sciences estimated that nearly 60,000 children each year

are born at risk for neurological problems due to methylmercury

exposure in the womb. Recent data suggest the numbers could be much

higher because of the fish consumption of pregnant women.

What if I'm a man or older woman?

Unless there is an advisory about fish in your area, the FDA and EPA

have not expressed concern about methylmercury exposure for men or

women who are beyond reproductive age. However, people with impaired

kidney function, and those with very sensitive immune responses to

metals should be very careful to avoid mercury. Even if you are not

especially vulnerable, it makes sense to consider moderation if you

like to eat the fish that are higher in mercury. See the chart below

for a summary of mercury risk posed by specific types of fish.

Fish to avoid if you are/may be pregnant, nursing, or a young child

Fish to consume in limited

quantities if you are/may be pregnant,

nursing, or a young child

Fish lowest in

methylmercury

Shark

Swordfish

King Mackerel

Tilefish (a.k.a. golden bass, golden snapper)

Lower in mercury but still to be avoided:

Tuna steak (also used in sushi and sashimi)

Canned Albacore White Tuna Canned Light Tuna

Sea Bass

Gulf Coast Oysters

Marlin

Halibut

Pike

Walleye

White Croaker

Largemouth Bass Mahi Mahi

Blue Mussel

Cod

Eastern Oyster

Channel Catfish (wild)

Great Lakes Salmon

Gulf Coast Blue Crab

Lake Whitefish

Pollack Catfish (farmed)

King Crab

Scallops

Fish Sticks

Flounder (summer)

Trout (farmed)

Salmon (wild Pacific)

Shrimp

Tilapia

Sardines

http://www.center4research.org/methylmercury2.html

Good long life to all us! Stay Happy!

[Guest guest]

Maybe we need to eval the EPA/DHA content of the fish versus the methyHg?

Don't forget tetraethyl lead.

Regards.

----- Original Message -----

From: chuinyun

Sent: Wednesday, January 26, 2005 1:51 PM

Subject: [ ] Methylmercury in Fish: The Facts

Fish in news. We know healthy fish healthy for us. But which to choose?Help make right choice:Do you eat tuna or any other fish? If you do, read this:Methylmercury in Fish: The Factsby Anne Gallo, M.S. and Madeleine Levin, MPHWhat is methylmercury?Mercury is a mineral that exists naturally in the environment. Inaddition, thousands of tons are released into the air each yearthrough pollution and waste. Bacteria and natural processes cantransform mercury into the organic mercury compound methylmercury(MeHg), which is a poisonous substance.Unfortunately, this toxin is in the fish we eat. Methylmercury canenter the water or soil, accumulating in streams and oceans. It alsoaccumulates in the food chain, as each fish absorbs all the mercury ofthe smaller fish or organisms it has eaten. That is why the oldest andlargest fish, such as shark and swordfish, tend to have the highestlevels. Methylmercury levels are higher in people who regularly eat fish.

[Guest guest]

>>Maybe we need to eval the EPA/DHA content of the fish versus the methyHg?

Don't forget tetraethyl lead.

I did it and update it every year. Here is the latest.

Its on page 6-8

http://www.pritikin.com/pdf/2004/septoct04.pdf

Regards

jeff

[Guest guest]

Thanks Jeff,

Great article.

Pollock is .06 and it's cheap too.

But salmon (ugh) has 3 times as much EPA (USDA), for 6 oz, .71 versus .26 for: Pollock, walleye .26.

I guess that's the Alaska Pollock, I'm getting. Fresh salmon,wild is .01 ppm Hg.

Curious that the higher EPA/DHA also are the lower Hg.

Also, we get tilapia from Chile and china. Both are .01?

BTW, "whitefish" is ambiguous. ALL the types that go into "whitefish" are .03 ppm?

Regards.

----- Original Message -----

From: Jeff Novick

Sent: Thursday, January 27, 2005 5:58 AM

Subject: RE: [ ] Methylmercury in Fish: The Facts

>>Maybe we need to eval the EPA/DHA content of the fish versus the methyHg?Don't forget tetraethyl lead.I did it and update it every year. Here is the latest. Its on page 6-8http://www.pritikin.com/pdf/2004/septoct04.pdfRegardsjeff

[Guest guest]

Remember, these numbers are based on averages of various amounts of samples.

You can see where I got the numbers from here.,...

http://www.cfsan.fda.gov/~frf/sea-mehg.html

Jeff