USGS scientists collecting fish from the St. Marys River near MacClenny, Fla., for the National Fish Mercury Model data base. (Photo: USGS)

By Steve Beck

Eating fish and shellfish generally is very good for you. Fish and shellfish contain omega-3 fatty acids (good for the heart, among other benefits), high-quality protein and other important nutrients, and are low in saturated fat. Experts recommend that women and young children, in particular, should include fish and shellfish in their diets.

Eating mercury, on the other hand, can be very bad for you. It can harm the brain and nervous system — especially while they are still developing, as in a fetus or young child. In addition, ingested mercury tends to build up in the body and stay for prolonged periods. Children, and women who are pregnant or may become pregnant within a year or so, should particularly avoid foods containing mercury.

Unfortunately, mercury can be found throughout the Earth’s water supply and the food chain, and at least trace amounts are present in nearly all fish and shellfish. So how can we enjoy the nutritional benefits of seafood without poisoning ourselves?

Fortunately, small amounts of mercury are less likely to be harmful. And the amount in seafood varies. Many factors are involved, including where the fish is caught. But in general, fish that are larger, longer-lived and eat other fish are more likely to accumulate higher concentrations of mercury in their bodies. Smaller fish that are shorter-lived and lower on the food chain are less likely to do so.

Knowing this, we can make wise choices about what kinds of seafood to eat and how much. Mark Stibich, Ph.D., a health behavior expert writing for About.com, offers the following guidelines. (Note: A “serving” is about six ounces.)

Note that the recommended amounts per week or month are averages. Small short-term variations are unlikely to cause harm. So if you have a little more than the recommended amount one month, just have a little less the following month.

For fishing enthusiasts: Your local rivers, lakes or coast may have higher-than-usual levels of mercury, so check local advisories about the safety of fish that you or your friends may catch there. If no advice is available, the Environmental Protection Agency (EPA) recommends that you eat no more than one serving of such fish per week, and don’t consume any other fish during that week.

Follow these steps, and you can enjoy the substantial health benefits of seafood without undue risk from mercury.

Another fish to fry: reducing mercury pollution

So much for keeping mercury out of you — how can you keep it out of the environment in the first place?

Most mercury pollution comes from industrial processes. There are also natural sources such as volcanoes. However, you can take steps to avoid contributing to the problem:

• Use digital rather than mercury thermometers. Many cities, and some hospitals and clinics, have exchange programs that let you trade your mercury thermometer for a free digital replacement.

• If you break a mercury thermometer, don’t flush the mercury down the toilet, pour it down the drain or throw it in the regular trash. Instead, carefully sweep the little beads of mercury into a disposable plastic container you can seal shut, and take the container to a local household hazardous waste collection facility for disposal. If mercury spills on a carpet or rug, you should probably just get rid of those items — mercury is very difficult to remove and will release harmful vapors over time.

These steps may not clean up the whole world — but they will help reduce mercury contamination in your own little part of it.

Tags: fish, Mercury, shellfish

Monday, January 25th, 2010 | Food, Health, Social |