Blood and Hair Mercury Levels in Young Children and Women of Childbearing Age — United States, 1999

The Federal Government Report:

Blood and Hair Mercury Levels in Young Children and Women of Childbearing Age – United States, 1999. Reported by: Center for Food Safety and Applied Nutrition, Food and Drug Administration. U.S. Environmental Protection Agency. National Energy Technology Laboratory, Dept of Energy. National Marine Fisheries Laboratory, National Oceanic and Atmospheric Administration. National Center for Health Statistics; National Center for Environmental Health, CDC.
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5008a2.htm

Review This Federal Government Report Executive Summary:
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5008a2.htm

The Purpose of this Federal Government Report:
This federal government report presents preliminary estimates of blood and hair mercury levels from the 1999 National Health and Nutrition Examination Survey (NHANES 1999) and compares them with a recent scientific review by the National Research Council (NRC).

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

This is not a peer-reviewed, scientific paper.
This federal report was first publicly distributed in 1999.
The U.S. population primarily is exposed to methylmercury by eating certain types of fish.
Methylmercury exposures to women of childbearing age are of great concern because an unborn child is highly susceptible to the bad effects believed to be caused by methylmercury exposure on the developing human brain and/or nervous system.
The National Health and Nutrition Examination Survey (NHANES) 1999 blood and hair mercury data are the first nationally representative human tissue measures of the U.S. population's exposure to mercury. Previous estimates of methylmercury exposure in the general population were based on exposure models using fish tissue methylmercury levels and dietary recall survey data.
The findings in this federal government report are subject to at least three limitations.

First, the ratio of mercury in the umbilical cord and the mercury in the mother’s blood is uncertain. The National Research Council (NRC) scientific committee summarized some scientific studies that suggest that umbilical cord blood methylmercury values may be 20%-30% higher than corresponding methylmercury levels found in the mother’s blood. However, other scientific studies suggest that the ratio is closer to 1:1. Therefore, the NHANES values may not be directly comparable to the methylmercury level(s) believed to be safe by the National Research Council (NRC).
Second, National Health and Nutrition Examination Survey (NHANES) cannot provide estimates of mercury exposure in certain, highly exposed groups of people including subsistence fishermen and others who regularly eat large amounts of fish. Published data from scientific studies of certain, highly-exposed U.S. populations indicate that some people have methylmercury blood levels greater than what is believed to be safe by various federal methylmercury regulating agencies.
Third, the number of people studied in National Health and Nutrition Examination Survey (NHANES) 1999 was small. Plus, the National Health and Nutrition Examination Survey (NHANES) 1999 study was conducted in only 12 locations. More data are needed to confirm these findings.

The long-term strategy to reduce human methylmercury exposure to lower methylmercury levels in fish is by limiting mercury releases into the air from burning mercury-containing fuel and waste – and from other industrial sources.
The short-term strategy to reduce human methylmercury exposure is to eat certain types of fish with low methylmercury levels and to avoid (or to only moderately eat) certain types of fish with high methylmercury levels.
State-based fish advisories and bans identify certain types of fish contaminated by methylmercury and their locations - and provide safety advice. http://www.epa.gov/ost/fish
The Food and Drug Administration (FDA) advises pregnant women and those women who may become pregnant not to eat shark, swordfish, king mackerel, and tilefish. These types of fish are known to contain elevated levels of methylmercury. Additional useful information is available at http://www.fda.gov/bbs/topics/ANSWERS/2001/advisory.html

A Bottom Line:

The findings of this federal government report suggest that mercury levels in young children and women of childbearing age generally are below those considered hazardous.
These preliminary estimates show that approximately 10% of women have mercury levels within one tenth of potentially hazardous mercury levels indicating a narrow margin of safety for some women – and supporting efforts to reduce methylmercury exposure in general.
The National Research Council (NRC) review study provided guidance to the Environmental Protection Agency (EPA) for developing an exposure reference dose for methylmercury (i.e., an estimated daily exposure that probably is free of risk for bad effects over the course of a person's life). The National Research Council (NRC) report recommends statistical modeling of results from a certain type of scientific study conducted in the Faroe Islands near Iceland, where methylmercury exposures are high because of the large amount of seafood (including pilot whale meat and/or blubber) regularly eaten by the local people. Results of this study were used to calculate an estimate of a methylmercury exposure in the womb associated with an increase in detectable bad effects caused by mercury in children.
This federal government report recommends that efforts aimed at decreasing human methylmercury exposure must continue.

Find This Federal Government Report for Your Review:
Blood and Hair Mercury Levels in Young Children and Women of Childbearing Age – United States, 1999. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5008a2.htm

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