pregnant womanBlood mercury levels in women of childbearing age have dropped 34 percent in the past 14 years, according to a survey by the EPA. Additionally, the percentage of women of childbearing age with blood mercury levels above the level of concern decreased 65 percent from the 1999-2000 survey and follow-up surveys from 2001-2010.

Eating better types of fish

During the survey period there was very little change in the amount of fish consumed. The decrease in the ratio of mercury intake to fish consumed suggests that women may have shifted to eating types of fish with lower mercury concentrations.

For the peer-reviewed study, Trends in Blood Mercury Concentrations and Fish Consumption among U.S. Women of Childbearing Age, NHANES (1999-2010), the EPA analyzed measurements of blood mercury levels from the Center for Disease Control and Prevention’s National Health and Nutrition Examination Survey. EPA found that blood methylmercury concentrations in women of childbearing age in the first survey cycle (1999-2000) were 1.5 times higher than the average concentration of the five subsequent cycles (2001-2010). The average of blood mercury concentrations changed only slightly from 2001 to 2010, and remained below levels of concern for health.

Locally caught fish could differ

EPA’s study provides a nationwide perspective on trends in mercury levels based mostly on consumption of ocean fish. It does not reflect trends in mercury levels in communities that depend on locally caught fish for subsistence. EPA and states recommend that people check local advisories before eating fish caught from local waterways.

Fish and shellfish are an important part of a healthy diet because they are a source of high-quality protein, many vitamins and minerals, omega-3 fatty acids, and are mostly low in saturated fat. A well-balanced diet that includes a variety of fish and shellfish can be beneficial for heart health and children's proper growth and development.

The reproductive risk

However, nearly all fish and shellfish contain traces of mercury. For most people, the risk from mercury by eating fish and shellfish is not a health concern. Yet, some fish and shellfish contain higher levels of mercury that may harm an unborn baby or young child's developing nervous system. The risks from mercury depend on the amount of fish and shellfish eaten and the levels of mercury in the fish.

EPA and the U.S. Food and Drug Administration (FDA) advise women who may become pregnant, pregnant women, nursing mothers, and young children to avoid some types of fish and to eat fish and shellfish that are low in mercury for the health benefits and to reduce exposure to mercury.

EPA and FDA advise:

  • Do not eat shark, swordfish, king mackerel or tilefish because they have high levels of mercury.
  • Eat up to 12 ounces (2 average meals) per week of a variety of fish and shellfish low in mercury.
  • Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, pollock, and catfish.
  • Another commonly eaten fish, albacore ("white") tuna has more mercury than canned light tuna. So, when choosing two meals of fish and shellfish, you may eat up to 6 ounces (one average meal) of albacore tuna per week.
  • Check local advisories about the safety of fish caught in local lakes, rivers, and coastal areas. If no advice is available, eat up to 6 ounces (one average meal) per week of fish caught from local waters, but don't consume any other fish during that week.
  • Follow these same recommendations for young children, but serve smaller portions.

The EPA and the FDA issued national mercury advisories on fish consumption in 2001 and 2004.

In 2013, the agency proposed new effluent guidelines for steam electric power plants, which currently account for more than half of all toxic pollutants discharged into streams, rivers and lakes from industrial facilities in the U.S. In April, EPA issued the new Mercury and Air Toxics rule, which sets emissions limitation standards for mercury emitted from power plants. Compliance with this rule may take up to four years.

More information: