Associations Between Gestational Environmental Phenols and Preterm Birth; a Nested Case-Control Study

Abstract

BACKGROUND AND AIM: Studies report associations between environmental phenols exposure and preterm birth (PTB). There is significant racial disparity in PTB rates yet little data to characterize the effects of phenol exposure by race. To begin to address this data gap we conducted a case-control pilot study, nested within a larger U.S. investigation. METHODS: We enrolled 26 women with a PTB (37 weeks completed gestation) and 26 women with a term delivery, matched by race (non-Hispanic Blacks and non-Hispanic whites). Participants provided urine specimens at 18-22 weeks gestation, completed a questionnaire, and allowed access to hospital records. We measured ten environmental phenols in urine, including methyl- (MP), ethyl- (EP), propyl- (PP), and butylparabens (BP), benzophenones 1 (BZP-1) and 2 (BZP-2), pentachlorophenol, triclosan, and bisphenols A (BPA) and S (BPS), using liquid chromatography-tandem mass spectrometry. After specific gravity correction, we estimated associations between environmental phenols and PTB using logistic regression, adjusted for race, age, body mass index, and education. We tested interactions by race. RESULTS:Urinary BZP-1 (difference=12.01 ng/mL; P=0.001) and BZP-2 (difference=162.24 ng/mL; P=0.01) concentrations were greater among whites, and pentachlorophenol (difference=0.40 ng/mL; P=0.01) and BPS (difference=0.40 ng/mL; P=0.01) were greater among Blacks. Higher urinary BP was associated with greater odds of PTB (odd ratio (OR)=1.32; 95%CI:0.95-2.43), while higher urinary BZP-1 (OR=0.96; 95%CI:0.91-0.99), pentachlorophenol (OR=0.62; 95%CI:0.18-2.01), triclosan (OR=0.98; 95%CI:0.97-0.99), and BPS (OR=0.75; 95%CI:0.35-1.47) were associated with lower odds of PTB, although some confidence intervals were imprecise. We detected an interaction for race (P=0.08), such that Blacks had lower PTB odds (OR=0.70; 95%CI:0.29-1.02) than whites (OR=0.97; 95%CI:0.92-1.00) in association with higher BZP-1. CONCLUSIONS:In this pilot study, exposure to environmental phenols differed by race and individual phenols demonstrated variable associations with PTB risk. It does not appear that exposure to environmental phenols was associated with a greater risk of PTB in either Black or white mothers. KEYWORDS: Phenols, Environmental disparities, birth outcomes