Maternal occupational exposure to organic solvents during early pregnancy and selected congenital anomalies Public Deposited

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  • March 21, 2019
Creator
  • Desrosiers, Tania A.
    • Affiliation: Gillings School of Global Public Health, Department of Epidemiology
Abstract
  • Background: As more women enter the labor force, there is increased epidemiologic interest in the possible effects of employment and occupational exposures on adverse pregnancy outcomes. Using data from the National Birth Defects Prevention Study, we examined the prevalence and patterns of maternal employment before and during pregnancy, and examined the relation between maternal occupational exposure to organic solvents during the periconceptional period (first trimester and month before conception) and neural tube defects (NTDs) and orofacial clefts (OFCs), which toxicological data suggest may be susceptible to oxidative stressors like solvents. Methods: Cases of NTDs (anencephaly; spina bifida; encephalocele) and OFCs (cleft lip [plus or minus] cleft palate; cleft palate) delivered between 1997 and 2002 were identified by birth defect surveillance registries in 8 states; non-malformed control infants were selected using birth certificates or hospital records. Exposure to aromatic, chlorinated and Stoddard solvents were estimated by industrial hygienist review of self-reported occupational histories in combination with a literature-derived exposure database. We used employment dates to examine variability in employment status and estimated exposure prevalence to any solvent across different time periods before and during pregnancy among controls. Odds ratios (OR) and 95% confidence intervals (CI) for the association between solvent class and each birth defect group and component phenotype were estimated using logistic regression, adjusting for maternal age, race/ethnicity, education, pre-pregnancy body mass index, folic acid supplement use and smoking. Results: Over 70% of mothers worked at some point 3 months before and during pregnancy; employment status was not constant throughout pregnancy for 25% of these women. The prevalence of estimated exposure to any solvent during the periconceptional period among mothers of NTD cases (n=511), OFC cases (n=1163) and controls (n=2997) was 13.1%, 9.6% and 8.2%, respectively. No solvent class was associated with OFCs in these data. Exposure to chlorinated solvents was associated with increased odds of NTDs (OR=1.96; CI=1.34, 2.87), particularly spina bifida (OR=2.26; CI=1.44, 3.53). Conclusions: Future studies of maternal employment should focus on the biologically relevant critical exposure window to reduce misclassification. Maternal occupational exposure to chlorinated solvents during early pregnancy may be associated with NTDs and merits further research.
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  • In Copyright
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  • " ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Epidemiology, Gillings School of Global Public Health."
Advisor
  • Olshan, Andrew
Degree granting institution
  • University of North Carolina at Chapel Hill
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Place of publication
  • Chapel Hill, NC
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  • Open access
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