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Association between Maternal Occupational Exposure to Polycyclic Aromatic Hydrocarbons and Risk of Selected Birth Defects in the National Birth Defects Prevention Study

Year: 2018
Type: article
Study design: Observational Study
Abstract: Background: Polycyclic aromatic hydrocarbons (PAHs) are a group of persistent chemicals created by the incomplete combustion of organic substances.Analyses from the first five years of the National Birth Defects Prevention Study (NBDPS), the largest population-based case-control studies of birth defects in the United States, found that exposure to occupational PAHs may be associated with increased risk of adverse reproductive outcomes, including birth defects.The purpose of this study was to use the full data (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011) from NBDPS to evaluate the relationship between maternal occupational exposures to PAHs and selected birth defects (neural tube defects and rare facial and central nervous system defects), and to develop semi-automated approaches to the exposure assessment of PAHs.Methods: Data from over 35,000 employed women in the NBDPS were analyzed.Expert raters assigned each job PAH exposure ratings; this included intensity, percent of time exposed, and rating confidence for likely exposed jobs.Crude and adjusted odds ratios (ORs) were calculated using multivariate logistic regression.Effect modification was evaluated with stratification.Exposure-response analyses used PAH cumulative exposure estimates categorized into none versus quartiles or into none, low, and high.To increase efficiency of future exposure assessments, the entire dataset of job descriptions and ratings was divided into training and validation data sets.Regularized logistic regression was used to derive a PAH exposure prediction model from the job descriptions and expert rating assignments from the training set, and the performance of the resulting algorithm plus manual keyword screen were compared to expert raters in the validation data set.Results: Approximately 10% of employed mothers were exposed to occupational PAH.Exposureresponse results showed that PAH exposure at the highest estimated exposure quartile was associated with any NTD (aOR: 1.45, 95% CI: 1.05-1.99)and with anencephaly (cOR: 1.72, 95% CI: 1.04-2.86)and spina bifida (cOR: 1.52, 95% CI: 1.02-2.27),with evidence of an exposure-response relationship.Holoprosencephaly and hydrocephaly showed statistically significant ORs (aOR: 2.09, 95% CI: 1.24-3.51and aOR: 1.66, 95% CI: 1.22-2.27,respectively) among exposed mothers.Findings from the main exposure-response analysis showed that at the high exposure level, PAH was significantly associated with cataracts (aOR = 1.61, 95% CI: 1.00-2.58),microtia (aOR = 1.74, 95% CI: 1.19-2.54),microphthalmia (aOR = 1.94, 95% CI: 1.13-3.33),and holoprosencephaly (aOR = 2.44, 95% CI: 1.27iii 4.69).At the low exposure level, PAH was significantly associated with hydrocephaly (aOR = 2.38, 95% CI: 1.66-3.43).The hybrid prediction model, which used an algorithm and keyword screen, demonstrated that by reviewing approximately 20% of the total jobs, it could identify 87% of all exposed jobs.Conclusions: Maternal occupational exposure to PAHs at greater estimated levels may be associated with increased risk of anencephaly, spina bifida, cataracts, microtia, microphthalmia, and holoprosencephaly.Using a combination of known retrospective exposure assessment approaches, we developed and tested an automated PAH exposure screening approach for use in a general population of employed mothers.
Language: English
Open Access status: green
OpenAlex ID: W7017500335
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