Mercury

Mercury contamination of our seafood is another environmental concern, especially for pregnant and lactating women and also for children.

Mercury is found naturally in our environment as part of our earth’s crust, but it is also accumulating because of human activity. The EPA estimates that approximately 160 tons of mercury are emitted annually in the US. Much of this enters into our environment from industrial emissions and waste products that contain mercury (mercury thermometers, blood pressure manometers, feeding tubes, certain batteries, fluorescent lights, thermostats). Hospitals contribute 4-5% of the total wastewater mercury load.

As mercury contaminates our waterways, it is converted by bacteria into methylmercury, which bioaccumulates as it passes up the food chain. Large predatory fish tend to have significant levels of mercury. In addition, freshwater fish are sufficiently contaminated with mercury so that the US state fish advisories in 40 states have issued warning for pregnant women to limit or avoid fish from their areas. According to EPA estimates, 1.16 million women of childbearing years eat sufficient amounts of mercury-contaminated fish to pose a health risk.

The current FDA consumer advisory states:

  • Pregnant women and women of childbearing age who might become pregnant should not eat shark, king mackerel, swordfish or tilefish because of their tendency to have high mercury content. It is prudent for children and nursing mothers not to eat these fish as well.
  • Pregnant women may eat 12 ounces a week of other varieties of fish.

Of concern to many environmental groups is that the EPA limits for mercury are stricter than the current FDA guidelines. The FDA guidelines considers 1 part per million (ppm) the acceptable limit for the level of methymercury in fish. The EPA guidelines considers 1/4 the level the FDA set as safe. Estimates presented from the March 2001 Consumer Reports issue, found that a 44-pound child should not eat more than one tuna fish sandwich a week and that a 132-pound woman would meet the EPA?s safe level by eating two tuna fish sandwiches a week.

What are the effects and the price we may pay when exposing infants and children to mercury? Unfortunate historical accidental poisonings have shown that infants born to mothers exposed to high doses of mercury had mental retardation, gait and speech disturbances and seizures. Smaller fetal exposures to mercury may impair language, attention and memory.

As we have learned historically with lead, a declining threshold of harm was identified over time. In 1960, the level of lead considered “safe” was set at 60 microgm/dl and in 1990 this was revised to 10 microgm/dl. Look for similar attention and reevaluation of the mercury issue as we learn more. However, by being proactive now, we can protect our environment, our children and our future generations.

Learn more about mercury and figure out how much mercury in your diet is safe at Got Mercury. If you work at a hospital, learn more at the Healthcare without Harm website and learn how to Green your hospital from mercury.