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Blood Mercury Levels in
US Children and Women of Childbearing Age, 1999-2000
Susan E. Schober, PhD;
Thomas H. Sinks, PhD; Robert L. Jones, PhD;
P. Michael Bolger, PhD, DABT;
Margaret McDowell, MPH, RD; John Osterloh,
MD, MS; E. Spencer Garrett, MS;
Richard A. Canady, PhD, DABT; Charles
F. Dillon, MD, PhD; Yu Sun, PhD;
Catherine B. Joseph, MSPH; Kathryn R.
Mahaffey, PhD
JAMA. 2003;289:1667-1674.
Context Humans are exposed to
methylmercury, a well-established neurotoxin,
through fish consumption. The fetus is most sensitive
to the adverse effects of exposure. The extent of
exposure to methylmercury in US women of
reproductive age is not known.
Objective To describe the distribution of
blood mercury levels in US children and women
of childbearing age and the association with
sociodemographic characteristics and fish consumption.
Design and Setting The 1999-2000 data from
the National Health and Nutrition Examination
Survey, a cross-sectional survey of the
noninstitutionalized US population.
Participants In 1999-2000, 1250 children aged
1 to 5 years and 2314 women aged 16 to 49
years were selected to participate in the
survey. Household interviews, physical examinations,
and blood mercury levels assessments were
performed on 705 children (56% response rate)
and 1709 women (74% response rate).
Main Outcome Measure Blood concentration of
total mercury.
Results Blood mercury levels were
approximately 3-fold higher in women compared
with children. The geometric mean concentration
of total blood mercury was 0.34 µg/L (95%
confidence interval [CI], 0.30-0.39 µg/L) in
children and 1.02 µg/L (95% CI, 0.85-1.20
µg/L) in women. Geometric mean mercury levels
were almost 4-fold higher among women who ate 3 or more
servings of fish in the past 30 days compared with
women who ate no fish in that period (1.94
µg/L vs 0.51 µg/L; P<.001).
Conclusions Measures of mercury exposure in
women of childbearing age and young children
generally fall below levels of concern.
However, approximately 8% of women had concentrations
higher than the US Environmental Protection
Agency's recommended reference dose (5.8
µg/L), below which exposures are considered
to be without adverse effects. Women who are pregnant or
who intend to become pregnant should follow
federal and state advisories on consumption
of fish.
Author Affiliations: National Center for
Health Statistics, Centers for Disease Control and
Prevention, Hyattsville, Md (Drs Schober and Dillon, and
Ms McDowell); National Center for Environmental Health,
Centers for Disease Control and Prevention, Atlanta, Ga
(Drs Sinks, Jones, and Osterloh); Center for Food Safety
and Applied Nutrition, Food and Drug Administration,
College Park, Md (Drs Bolger and Canady); National
Marine Fisheries Service, National Oceanic and
Atmospheric Administration, Pascagoula, Miss (Mr
Garrett); The Orkand Corporation, Falls Church, Va (Dr
Sun); and Office of Science Coordination and Policy,
Office of Prevention, Pesticides, and Toxic Substances,
Environmental Protection Agency, Washington, DC (Dr
Mahaffey and Ms Joseph). Dr Sun is now with
Chiacchierini & Associates, LLC, Rockville, Md.
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