Mercury in Fish

Mercury in Fish

The news and media recently have generated much controversy and confusion about mercury in seafood. Though mainly targeted at pregnant and nursing women, many people are left to wonder:

“How much fish should I eat?”
“Is fish safe?”
“Should I choose farmed or wild fish?”
“Which fish are the best to eat?”

While the research is still young, the following is the best information that we have to date:
Oceans are becoming increasingly contaminated with metals, industrial chemicals, and pesticides; the most researched offenders include:
Mercury
Lead
PCBs
DDT
Dieldrin
The strongest concern lies in consumption of tainted fish by pregnant women, as unknown levels of ingestion may cause birth defects or cancer; small children also are a high-risk group
Methylmercury binds to protein and is found throughout the fish muscle; so, both fish steaks and filets may contain mercury
PCBs accumulate in fatty tissues of fish—high concentrations pose health risks to those who consume large amounts

It can take 12-18 months to reduce levels of mercury in the body and up to 5 years to rid the body of mercury entirely; for this reason, it is important that women who expect to become pregnant decrease their intake to avoid consumption of tainted fish

Always weigh the risk-to-benefit ratio of consuming fish for their omega-3 benefits against the potential harm from consuming fish that is possibly contaminated

Fish that are high in omega-3s, low in environmental contaminants, and eco-friendly include:
Wild salmon from Alaska (fresh, frozen, and canned)

Arctic char
Atlantic mackerel
Sardines
Sablefish
Anchovies
Farmed oysters
Farmed rainbow trout
Albacore tuna from the United States and Canada

Fish oil is an alternative to consuming fish, but chemicals and metals can build up in the oil, as well; choose purified fish oil capsules as the best alternative

Fish with low levels of mercury
Enjoy these fish:

Anchovies
Butterfish
Catfish
Clams
Crab (domestic)
Crawfish/crayfish
Croaker (Atlantic)
Flounder*
Haddock (Atlantic)*
Hake
Herring
Mackerel (North Atlantic, chub)
Mullet
Oysters
Perch (ocean)
Plaice
Pollock
Salmon (canned)†
Salmon (fresh) †
Sardines
Scallops*
Shad (American)
Shrimp*
Sole (Pacific)
Squid (calamari)
Tilapia
Trout (freshwater)
Whitefish
Whiting

Fish with moderate levels of mercury
Eat six servings or less/month of the following fish:

Bass (striped, black)
Carp
Cod (Alaskan)*
Croaker (white Pacific)
Halibut (Atlantic)*
Halibut (Pacific)
Jacksmelt (silverside)
Lobster
Mahimahi
Monkfish*
Perch (freshwater)
Sablefish
Skate*
Snapper*
Tuna (canned chunk light)
Tuna (skipjack)*
Weakfish (sea trout)

Fish with high levels of mercury
Eat three servings or less/month of the following fish:

Bluefish
Grouper*
Mackerel (Spanish, gulf)
Sea bass (Chilean)*
Tuna (canned albacore)
Tuna (yellowfin)*

Fish with the highest levels of mercury
Avoid eating the following fish:

Mackerel (king)
Marlin*
Orange roughy*
Shark*
Swordfish*
Tilefish*
Tuna (bigeye, ahi)*

*Fish in trouble: These fish are perilously low in numbers or are caught using environmentally destructive methods

†Farmed salmon: May contain PCBs, chemicals with serious long-term health effects
References

Natural Resources Defense Council. Consumer guide to mercury in fish. Available at: www.nrdc.org/health/effects/mercury/guide.asp. Accessed July 14, 2008.

Environmental Defense Fund. Contaminants in fish and shellfish. Available at: www.edf.org/page.cfm?tagID=16283. Accessed July 14, 2008.