Know Your Fish

How Safe Is Seafood?

For over two decades, researchers proclaiming the health benefits of fish — it's low in fat, high in protein, and rich in cardioprotective omega-3 fatty acids — have encouraged Americans to up their intake. The result: Each of us now eats a record 16.6 pounds every year, including double the amount of shrimp and salmon we consumed in 1994. But lately, headline-grabbing studies have warned that dangerous contaminants in lakes, rivers, and oceans may make seafood too risky.

The biggest health hazard is mercury, a toxic heavy metal linked to neurological problems in developing fetuses and children. Long-living fish have the highest concentrations of mercury. Last fall, reports from both the Institute of Medicine and the Harvard Medical School agreed with a 2004 governmental advisory that four mercury-tainted fish — shark, swordfish, tilefish (also called golden snapper or golden bass), and king mackerel — should never be eaten by pregnant women, women who may become pregnant, nursing mothers, and kids under 12. The advisory also recommended limiting the intake of canned albacore tuna and tuna steaks to 6 ounces per week for this group.

For almost everyone else, however, the studies determined that the benefits of moderate seafood consumption greatly outweigh the risks. In fact, the Harvard research found that people who have one to two servings of seafood each week might reduce their heart attack risk by a whopping 36 percent. If you're adding more seafood to your family's diet, vary the menu to reduce the risk of mercury contamination from a single source; choose low-mercury varieties like catfish, shrimp, and scallops; and switch to chunk light tuna, which usually averages one-third the mercury levels of albacore.

PCBs (polychlorinated biphenyls), chemical compounds banned in the 1970s as probable carcinogens, are also found in some seafood. In 2004, a study found that farmed salmon, which accounts for 90 percent of the salmon in supermarkets, contained markedly higher levels of PCBs than wild salmon. The reason: Farmed salmon are typically fed a diet of ground fish meal and fish oils, which are high in PCBs. According to a 2004 study in the journal Science, there's a more than sevenfold difference in the PCB levels of wild and farmed salmon. Some consumer groups advise that you limit your intake of farm-raised salmon to a single, 8-ounce (or less) meal a month. The FDA, however, counters that salmon is a powerhouse source of cardiovascular-friendly omega-3 and that the likelihood of developing cancer from PCBs is much lower than the risk of heart disease from avoiding salmon — wild or farmed.

The Safest Choices

These fish and shellfish are low in mercury, PCBs, dioxins, and other contaminants.

Catfish (U.S. farm-raised)
Clams
Cod (Pacific)
Crab
Haddock
Halibut (Pacific)
Herring
Lobster
Mahimahi
Mussels
Oysters
Pollack
Salmon (wild, canned)
Sardines
Scallops
Sea bass
Shrimp
Squid
Tilapia
Trout (farm-raised)
Tuna (canned light)


Eat in Moderation

Limit your consumption of these fish and shellfish to no more than four 6-ounce servings per month. For women who are or may become pregnant, nursing mothers, and children under 12, the Institute of Medicine recommends no more than 6 ounces of albacore each week.

Albacore tuna (canned white)
Blue crab
Bluefish
Flounder
Halibut (Atlantic)
Marlin (blue)
Salmon (farm-raised)
Tuna (ahi or bigeye, yellowfin, and bluefin)


Be Very Cautious with These

According to both the EPA and the FDA, women who are or may become pregnant, nursing mothers, and children under 12 should avoid these fish because of the levels of mercury contamination in them.

King mackerel
Shark
Swordfish
Tilefish (also called golden snapper and golden bass)