Pass the Fish, Hold the Toxins
by Mindy Pennybacker
At the end of a summer day, it's a fine thing to amble along a wharf as fishermen reel in their catch, whetting our appetites for dinner. Until quite recently, we could assume that any fish or shellfish would make a healthy meal and that there'd always be more. Today, overfishing, destructive fish farming, and toxic contaminants have complicated the menu. But we can still find lots of fish that have been harvested sustainably, and are healthful as well. We simply have to look a little closer before ordering that captain's platter or seafood grill. Here's why and how.
Mercury, released into the air by power plants and waste incinerators, turns to neurotoxic methylmercury in water, where it collects in the bodies of fish and shellfish. In adults, signs of mercury poisoning include headache, fatigue, decreased memory, and joint pain. But because adults aren't growing, we can generally recover after we stop eating contaminated fish, as our bodies gradually excrete the toxin. When fetuses and children are exposed, however, mercury can harm nervous system and brain development, according to Philip J. Landrigan, M.D., director of the Center for Children's Health and the Environment at the Mount Sinai School of Medicine. The U.S. Centers for Disease Control report that 16 percent of American women of child-bearing age have levels of mercury in their blood high enough to put their offspring at increased risk. In 1999-2000, more than 300,000 newborns in the U.S. may have been exposed to "unacceptable levels" of mercury through their mothers' fish consumption, according to a study published in the April 2004 Environmental Health Perspectives. Mercury exposure through diet is a worldwide problem: USA Today reports that in Hong Kong, where the harbor is heavily polluted, 10 percent of high school students have been found to have unsafe blood mercury levels of more than 5 micrograms per kilo of body weight.
Studies show that other neurotoxins, especially polychlorinated biphenyls (PCBs), have caused developmental damage in children whose mothers regularly ate fish from polluted rivers and lakes. A study published in Science in January 2004 discovered PCBs and other persistent organic pollutants (POPs), such as dioxins and pesticides, at levels that were several times higher in farmed salmon than in wild. Because POPs accumulate in animal fat, animal protein in farmed fish feed was the likely cause, the researchers said.
By being selective, we consumers can protect our own health and at the same time encourage the recovery of threatened fish populations, as the recent campaigns Save the Swordfish and Boycott Chilean Sea Bass (actually Patagonian toothfish) have shown. The Monterey Bay Aquarium and other environmental groups regularly publish lists of fish that are harvested from farms and fisheries that are being well-managed, without by-catch.
So, how to keep it all straight? Here are some simple steps:
- Find out about a fish: What does it eat? Because pollutants accumulate in animal bodies and rise in the food chain, big predator species such as tuna, swordfish and sharks tend to have highest mercury levels, although canned light salmon contains only moderate mercury. Wild salmon, flounder and sole (which feed on small fish), and herring and sardines are low in mercury.
- Ask your retailer or restaurateur, where did it come from? Both pollutant levels and health of fisheries vary according to locale. For instance, Pacific cod, flounder, and sole are from recovering populations, while their Atlantic kin are still endangered. Look for the label of the international Marine Stewardship Council, which certifies fish from sustainably managed fisheries.
- Consider who's going to be eating it. The FDA and EPA advise that young children, pregnant women, nursing mothers, and women of childbearing age eat not more than two or three meals, or 12 ounces total, of fish and shellfish a week, and limit high-mercury fish to once a week. To be safest, however, the Environmental Working Group and other environmental health advocates advise that young children, pregnant or nursing women, and those planning to become pregnant avoid high-mercury fish completely and limiting moderate-mercury fish to once a month.
- Cook with care. Avoid the skin and fatty parts of fish, where POPs collect. Grill or broil rather than fry.
- When you shop or eat out, take along a list of fish rated by human health and environmental standards. It's free at www.thegreenguide.com/doc.mhthm?i=100&s=fish.
Remember, as consumers, we're not off the hook. If we are going to continue to be able to enjoy fish, we can't eat them all up.
Mindy Pennybacker is editor of Green Guide, published by The Green Guide Institute, which provides the research for this department.