Research
Obstetrics
Blood mercury concentrations in pregnant and nonpregnant women in the United States: National Health and Nutrition Examination Survey 1999-2006

Presented as a poster at the 46th annual meeting of the Society for Epidemiologic Research, Boston, MA, June 18-21, 2013, and the annual meeting of the Society for Pediatric and Perinatal Epidemiologic Research, Boston, MA, June 17-18, 2013.
https://doi.org/10.1016/j.ajog.2013.10.884Get rights and content

Background

Prenatal exposure to methylmercury is associated with adverse neurologic development in children. We examined total blood mercury concentrations and predictors of higher blood mercury concentrations in pregnant and nonpregnant women.

Methods

We analyzed data from 1183 pregnant and 5587 nonpregnant women aged 16-49 years from the 1999-2006 National Health and Nutrition Examination Survey (NHANES). We estimated geometric mean blood mercury concentrations and characteristics associated with higher mercury concentrations (≥3.5 μg/L) in crude and adjusted linear and logistic regression models.

Results

After adjusting for age and race/ethnicity, geometric mean blood mercury concentrations were clinically similar but significantly lower for pregnant (0.81 μg/L; 95% confidence interval [CI], 0.71–0.91) and nonpregnant women of childbearing age (0.93 μg/L; 95% CI, 0.87–0.99); 94% of pregnant and 89% of nonpregnant women had blood mercury concentrations below 3.5 μg/L. The most significant predictor of higher blood mercury concentrations for both pregnant and nonpregnant women was any seafood consumption vs no consumption in the last 30 days (odds ratio, 18.7; 95% CI, 4.9–71.1; odds ratio, 15.5; 95% CI, 7.5–32.1, respectively). Other characteristics associated with ≥3.5 μg/L blood mercury concentrations were older age (≥35 years), higher education (greater than high school), and higher family income to poverty ratio (3.501+) for both pregnant and nonpregnant women.

Conclusion

Pregnancy status was not strongly associated with blood mercury concentrations in women of childbearing age and blood mercury concentrations above the 3.5 μg/L cut were uncommon.

Section snippets

Data source

We used the National Health and Nutrition Examination Survey (NHANES) data obtained from 1999 through 2006. NHANES is a stratified, multistage probability sample of the civilian, noninstitutionalized population of the US conducted by the National Center for Health Statistics (NCHS) of the US Centers for Disease Control and Prevention (CDC). The NCHS Research Ethics Review Board approved the NHANES protocol. The consent form to participate in the survey as well to store specimens of their blood

Results

We analyzed data on 6770 women: 1183 pregnant and 5587 nonpregnant women from 1999 to 2006 who had completed interviews, examinations, and valid pregnancy data. Geometric mean BHg concentrations were significantly lower in pregnant women compared with nonpregnant women (0.71 and 0.92 μg/L, respectively; P < .0001). After adjustment for age and race/ethnicity, the difference in geometric mean BHg concentration between the groups was smaller, 0.81 and 0.93 μg/L, respectively, although still

Comment

We observed that geometric mean BHg concentrations were slightly, but statistically significantly, lower in pregnant women compared with nonpregnant women after adjusting for age and race/ethnicity. Given that the most significant driver of high BHg concentrations was seafood consumption for both pregnant and nonpregnant women, the lower concentrations of BHg in pregnant women may be due to fewer pregnant women consuming any seafood at all (a finding supported by this analysis), consuming fewer

Acknowledgments

The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the CDC. H.R. was supported by an appointment to the Research Participation program for the CDC administered by the Oak Ridge Institute for Science and Education through an agreement between the Department of Energy and CDC. H.R. and S.C.T. conducted the analysis. H.R., S.C.T., and K.C. developed the manuscript.

References (41)

  • B. Dye et al.

    Urinary mercury concentrations associated with dental restorations in adult women aged 16-49 years: United States, 1999-2000

    Occup Environ Med

    (2005)
  • Y. Zhang et al.

    An exposure assessment of methyl mercury via fish consumption for the Japanese population. risk analysis

    Risk Anal

    (2009)
  • M.D. Esteban-Vasallo et al.

    Mercury, cadmium and lead levels in human placenta: a systematic review

    Environ Health Perspect

    (2012)
  • S.E. Schober et al.

    Blood mercury levels in US children and women of childbearing age, 1999-2000

    JAMA

    (2003)
  • K.R. Mahaffey et al.

    Adult women's blood mercury concentrations vary regionally in the United States: association with patterns of fish consumption (NHANES 1999-2004)

    Environ Health Perspect

    (2009)
  • Toxicologic effects of methylmercury

    (2000)
  • P.W. Davidson et al.

    Longitudinal neurodevelopmental study of Seychellois children following in utero exposure to methylmercury from maternal fish ingestion: outcomes at 19 and 29 months

    Neurotoxicol

    (1995)
  • P.W. Davidson et al.

    Effects of prenatal and postnatal methylmercury exposure from fish consumption on neurodevelopment: outcomes at 66 months of age in the Seychelles Child Development Study

    JAMA

    (1998)
  • P. Grandjean et al.

    Methylmercury exposure biomarkers as indicators of neurotoxicity in children aged 7 years

    Am J Epidemiol

    (1999)
  • Kjellstrom T, Kennedy P, Wallis S, Mantell C. Physical and mental development of children with prenatal exposure to...
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    The authors report no conflict of interest.

    Cite this article as: Razzaghi H, Tinker SC, Crider K. Blood mercury concentrations in pregnant and nonpregnant women in the United States: National Health and Nutrition Examination Survey 1999-2006. Am J Obstet Gynecol 2014;210:357.e1-9.

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