Surf Like a Girl ::: In the Know News Report: Should You Worry About Mercury in Fish?

You've probably heard that pregnant women aren't supposed to eat sushi because of the high mercury levels in fish. Maybe you saw the headlines a couple of years ago when the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) issued their joint report on the dangers of mercury levels in seafood. But wait—seafood is good for you, right? It's actually a big balancing act: the protein and omega-3 fatty acids found in seafood (good) versus the methylmercury levels (bad). Just how bad? That depends.

Let's start with mercury. Mercury, that silvery substance in thermometers and in some dental fillings, is an organic substance found in rocks and soil. It also comes from industrial pollution; emissions are produced from power plants, car exhaust, and waste facilities. (So, yes, there are ways in which mercury production can be limited in the environment, with proper regulations.) The mercury makes its way into water sources, where particles mix with organisms to create methylmercury. Small fish ingest the methylmercury and bigger fish ingest the smaller fish, right up the chain. The simple rule is that the bigger the fish, the higher levels of methylmercury.

For humans, methylmercury is a neurotoxin. Women who are pregnant or nursing and ingest what most of us would consider small amounts can put their unborn children at risk for birth defects or other neurological damage. Even more surprising: women who are considering getting pregnant are in danger. Just as the big fish accumulate the methymercury in their systems, we hold onto it in ours—which is why women who are thinking about becoming pregnant should curb their fish consumption. "Detoxing" can take upwards of a year.

In the last couple of years, more than 40 states have issued warnings about the high levels of mercury in fish but there's been little action to ensure that consumers are informed and warned. (While tobacco companies were finally forced to put warning labels on cigarette packaging, you won't find a warning label on a can of tuna.) The FDA published its guidelines for safe levels of mercury in fish but the consumer need to actively seek the information.

How much is too much? Consider this: an albacore tuna sandwich surpasses the weekly FDA guidelines for women and children. Yes, that's one serving. It's generally recommended that women of childbearing age consume only 12 ounces per week. The average consumption is crucial, as methymercury absorption in the body is cumulative. Canned light tuna, salmon, shrimp, and catfish are among the fish with lower levels or methylmercury. High levels can be found in swordfish, shark, king mackerel, grouper, and tilefish. When selecting canned tuna, consider that albacore tuna has more methylmercury than chunk light.

For more specific information, consult the FDA website or the EPA website. Also check out how much mercury you're consuming with the online mercury calculator from gotmercury.org. —Stef McDonald