Are There Any Fish I Can Eat?

A reader asks The Green Guide:

Now that mad cow disease has been found in America, I want to feed my family more fish and less beef, but I'm also worried about unhealthy levels of mercury in tuna and cancer-causing chemicals in farmed salmon! My daughter is in preschool, and I'm pregnant again. Plus, we'd like to avoid eating overfished species. Which fish can I in good health and conscience buy?

The Green Guide responds:

It's wonderful that you care about fish populations as well as your family's health. The good news is that there are still lots of fish, rich in protein and heart-healthy omega-3 fatty acids, that are low in toxins and not overfished. These include wild Alaskan salmon, which can be bought fresh from May through September and frozen or canned the rest of the year, and sardines (which are high in calcium if you eat the bones). Here's a breakdown of the toxins most commonly found in fish, and how to avoid them.

Mercury

Because you're pregnant and have a young child, you have good reason to be cautious about dietary exposure to mercury, which is found at highest levels in some species, such as tuna and swordfish. Fetuses, infants and young children, whose brains and nervous systems are rapidly developing, are at greatest risk of harm from neurotoxins such as mercury. "Mercury ingested during pregnancy can damage an unborn baby's central nervous system, leaving the baby with slower than normal brain development," Philip J. Landrigan, M.D., Herbert L. Needleman, M.D. , and Mary Landrigan, M.P.A. write in Raising Healthy Children in a Toxic World (Rodale, 2001).

Because mercury is stored in our bodies, just as it is in fish, women planning to have children should also avoid high-mercury fish well before they become pregnant. According to the Centers for Disease Control, 8 percent of American women of child-bearing age have levels of mercury in their blood high enough to indicate increased chance of harm to their fetuses. Adults can suffer harm, as well: In April, 2003, Environmental Health Perspectives reported that 89 percent of study subjects, chosen if they ate a significant amount of fish or showed symptoms consistent with mercury poisoning, such as fatigue, headache, decreased memory and joint pain, had blood mercury levels above the EPA's safety threshold of 5 micrograms per liter.

The Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) advise that, in general, young children, pregnant women, nursing mothers and women of childbearing age should eat no more than two or three meals, 12 ounces total, of fish and shellfish a week. High-mercury fish—defined by the government as shark, swordfish, king mackerel, and tilefish—should never be consumed by those individuals. But some environmental health organizations, including the Environmental Working Group (EWG), have also been recommending that people in these high-risk groups eat moderate-mercury fish no more than once a month, and high-mercury fish (including many not on the government''s list) not at all.

In December, after being pressed to do so for years by EWG and others, FDA finally mentioned tuna as a mercury-containing fish in its advisory to these high-risk groups, albeit only in draft form.

Persistent Organic Pollutants (POPs)

Polychlorinated biphenyls (PCBs), banned in the U.S. since 1977 and members of a class of chemicals known as persistent organic pollutants, or POPs, were found at far higher levels in farmed than in wild salmon, according to a study released in January 2004. POPs accumulate in animal fat and rise in the food chain, so that large predator fish will generally contain higher amounts. Because farmed salmon are raised on feed that can include ground-up animals and fish, their bodies accumulate these pollutants. Other POPs found in fish include the organochlorine pesticide dieldrin and dioxins— the result of chlorine paper bleaching and manufacturing and incineration of PVC plastic.

PCBs, which are neurotoxins, hormone disruptors and probable carcinogens, were found at levels seven times higher in farmed than in wild salmon. PCBs are also found at high levels in fish from polluted water bodies, varying from locale to locale; state health advisories list which fish should not be consumed by children, pregnant or nursing women, and women of childbearing age.

How to Avoid Fishborne Toxins

Avoiding Mercury

As a general rule, The Green Guide and our medical advisory board, including Drs. Landrigan and Needleman, agree with EWG's guidelines.

*Young children and pregnant or nursing women should not eat high-mercury fish, and should limit meals of moderate-mercury fish to once a month.

(This is a general rule, however, which means you shouldn't worry unduly if you or your child occasionally get your fish mixed up and eat the "wrong" kind. A once-in-a-while meal won't cause harm—it's regular ingestion that allows mercury to build up in the body.)

*Know your tuna: According to the FDA, tuna steak and canned albacore (white) tuna generally contain up to three times more mercury than canned light tuna. According to EWG guidelines, a pregnant woman or young child can eat 4-6 ounces of moderate-mercury, canned light tuna (one sandwich) per month—and, if they do so, should also avoid eating other mercury-containing fish for that time period.

*Fish lowest in mercury include: Wild salmon, sardines, squid, Arctic char, Atlantic Summer Flounder (Flukes), Pacific flounder, sanddabs, and scallops (these last three should be eaten once per month due to habitat damage or to allow their population to recover). For moderate and high mercury fish lists, and which fish are from healthy, recovering or overfished populations, see "Best Fish Picks for Your Health and the Sea's."

Avoiding POPs

Check with your state's department of health before eating fish from local fresh or ocean waters, as worrisome levels of PCBs as well as pesticides and other industrial chemicals may be present.

In General

*Limit fish consumption by category, not individual species. For example, both cod and mahimahi are moderate-mercury fish, and only one from this category should be eaten per month —not one meal of cod and one of mahimahi.

*If you're in a high-risk group, don't eat the skin and fatty parts of fish, where POPs collect. Eat grilled, baked and broiled rather than fried fish, to avoid fat.

*For lists of specific fish can be eaten regularly, once in a while, and not at all ("yes," "sometimes" and "no") fish, see our unique, downloadable pocket fish guide, "Smart Shopper's Fish Picks," which addresses both overfishing and pollutants in fish that threaten human health. It is regularly updated.

For more information, also see www.fda.gov, www.ewg.org, www.epa.gov/waterscience/fish and map1.epa.gov to learn which fish from which water bodies are currently safe or unsafe to eat.