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Children's Health Advance Publication

Environ Health Perspect; DOI:10.1289/ehp.1307804

Prenatal Organochlorine and Methylmercury Exposure and Memory and Learning in School-Age Children in Communities Near the New Bedford Harbor Superfund Site, Massachusetts

Sara T.C. Orenstein,1,2 Sally W. Thurston,3 David C. Bellinger,4,5 Joel D. Schwartz,1,2,5 Chitra J. Amarasiriwardena,2 Larisa M. Altshul,5,6 and Susan A. Korrick2,5
Author Affiliations close
1Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA; 2Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA; 3Department of Biostatistics and Computational Biology, School of Medicine and Dentistry, University of Rochester, Rochester, New York, USA; 4Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA; 5Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA; 6Environmental Health and Engineering, Inc., Needham, Massachusetts, USA
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This EHP Advance Publication article has been peer-reviewed, revised, and accepted for publication. EHP Advance Publication articles are completely citable using the DOI number assigned to the article. This document will be replaced with the copyedited and formatted version as soon as it is available. Through the DOI number used in the citation, you will be able to access this document at each stage of the publication process.

Citation: Orenstein ST, Thurston SW, Bellinger DC, Schwartz JD, Amarasiriwardena CJ, Altshul LM, Korrick SA. Prenatal Organochlorine and Methylmercury Exposure and Memory and Learning in School-Age Children in Communities Near the New Bedford Harbor Superfund Site, Massachusetts. Environ Health Perspect; http://dx.doi.org/10.1289/ehp.1307804.

Received: 25 October 2013
Accepted: 24 July 2014
Advance Publication: 25 July 2014

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Abstract

Background: Polychlorinated biphenyls (PCBs), organochlorine pesticides, and methylmercury (MeHg) are environmentally persistent with adverse effects on neurodevelopment. However, especially among populations with commonly experienced low levels of exposure, research on neurodevelopmental effects of these toxicants has produced conflicting results.

Objectives: We assessed the association of low-level prenatal exposure to these contaminants with memory and learning.

Methods: 393 children, born between 1993-1998 to mothers residing near a PCB-contaminated harbor in New Bedford, Massachusetts were studied. Cord serum PCB, DDE, and maternal peripartum hair Hg levels were measured to estimate prenatal exposure. Memory and learning were assessed at age 8 (range: 7-11) years using the Wide Range Assessment of Memory and Learning (WRAML), age-standardized to a mean of 100 and standard deviation of 15. Associations with each WRAML index – Visual Memory, Verbal Memory, and Learning – were examined with multivariable linear regression, controlling for potential confounders.

Results: While cord serum PCB levels were low (sum of 4 PCBs, mean: 0.3 ng/g serum; range: 0.01, 4.4), hair Hg levels were typical of the U.S. fish eating population (mean: 0.6 µg/g; range: 0.3, 5.1). In multivariable models, each µg/g increase in hair Hg was associated with, on average, decrements of -2.8 on Visual Memory (95% CI: -5.0, -0.6, p=0.01), -2.2 on Learning (95% CI: -4.6, 0.2, p=0.08), and -1.7 on Verbal Memory (95% CI: -3.9, 0.6, p=0.14). There were no significant adverse associations of PCBs or DDE with WRAML indices.

Conclusions: These results support an adverse relationship between low-level prenatal MeHg exposure and childhood memory and learning, particularly visual memory.


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