Perspective: Mercury and Health

The Scientific Paper:

P. M. Bolger, P. M. and B. A. Schwetz. New England Journal of Medicine (NEJM) Vol. 347, No. 22, 1735-1736. 2002.

Review This Scientific Paper’s Abstract:
http://content.nejm.org/cgi/content/short/347/22/1735

The Purpose of this Study:
These two Food and Drug Administration (FDA) scientists discuss what the safe levels of mercury exposure are for people in the United States who eat certain types of fish. These scientists review several of the more pressing mercury and fish eating issues as are also addressed by the Food and Drug Administration (FDA).

Some Background, Methods, Results, Caveats, and Other Select Points:

• This peer-reviewed, scientific paper was published in 2002.
• The 2002 Food and Drug Administration (FDA) national methylmercury advisory recommends that pregnant women - and women who may become pregnant - avoid eating types of fish with the highest average amounts of methylmercury: 1) king mackerel; 2) tilefish; 3) shark; and 4) swordfish. Particularly high methylmercury levels are found in these types of fish because methylmercury concentrates in certain types of fish that live a long time and are at the top of the seafood chain.
• The table (in this federal government report) lists methylmercury levels in these and other key commercial types of fish eaten in the United States. An even more comprehensive list is available from the FDA at http://www.cfsan.fda.gov/~frf/sea-mehg.html
• The advice to avoid the four types of fish with the highest methylmercury levels was extended to women who are breast-feeding and also to young children. There is no direct evidence of a link between the eating methylmercury contaminated fish and bad effects in these two groups of people. Breast-feeding women and young children were only included in the FDA methylmercury national advisory as a matter of caution because of they are very susceptible to bad effects caused by mercury exposure to their developing brains and/or nervous systems.
• The range of methylmercury levels in other commercial types of fish is fairly narrow, from trace levels to about 0.4 ppm. It is these low-methylmercury types of fish that are most commonly eaten in the United States. Accordingly, the FDA national methylmercury advisory recommends a balanced diet of eating seafood that keeps the methylmercury levels low.
• These fish-eating recommendations reflect not only the methylmercury levels in individual types of fish but also the amount of fish eaten over time and the frequency of eating these types of fish.
• Even among women who are pregnant or are likely to become pregnant, eating 12 oz (340 g) per week of a variety of certain cooked fish (excluding the four commercial types of fish listed above that have the highest methylmercury levels) is considered to be safe. If this advice is followed, then the resulting methylmercury exposures will be well below that reported to be associated with even subtle bad effects in the developing brain and/or nervous system of unborn children and of young children.
• This recommended level of fish eating is consistent with the recommendations of the American Heart Association and the Public Health Service. Both of these recommendations are based on the presumed cardiovascular benefit from eating certain fish.
• To begin to address some mercury exposure questions, the FDA sought the advice of its Food Advisory Committee. The Food Advisory Committee gave several recommendations including:
  1. Conducting a detailed assessment of just how much canned tuna is eaten and the associated level of methylmercury exposure;
  2. Defining what is meant by "a variety of fish”;
  3. Relating dietary recommendations to the age or size of a child;
  4. Working with other federal and state agencies to include commercial and recreational fish under the same umbrella methylmercury national advisory; and
  5. Expanding the monitoring of methylmercury levels to include measurement of levels in humans (in blood, hair, or both).

A Bottom Line:
These two scientists believe in the current estimate that 8 percent of U.S. women who become pregnant exceed the most conservative definition of a safe level of methylmercury exposure.

Find This Scientific Paper for Your Review:
Perspective: Mercury and Health. New England Journal of Medicine (NEJM) Vol. 347, No. 22, 1735-1736. 2002.