An evaluation of in utero polycyclic aromatic hydrocarbon exposure on the neonatal meconium microbiome

Area of Science:

• Environmental Health
• Microbiology
• Developmental Toxicology

Background:

• In utero exposure to environmental polycyclic aromatic hydrocarbons (PAHs) is linked to adverse neurodevelopmental outcomes, prematurity, and low birthweight.
• The gut microbiome acts as a crucial interface between the host and its environment, making it a potential mediator of PAH-induced health effects.
• Understanding the impact of prenatal PAH exposure on the infant gut microbiome is essential for elucidating disease pathways.

Purpose of the Study:

• To investigate the effects of in utero polycyclic aromatic hydrocarbon (PAH) exposure on the meconium microbiome composition and diversity in newborns.
• To explore associations between different levels of prenatal PAH exposure and measures of gut microbial alpha and beta diversity.
• To identify specific bacterial taxa that are differentially abundant in relation to prenatal PAH exposure.

Main Methods:

• Analysis of 49 mother-child dyads with full-term deliveries and adequate meconium samples from the Fair Start Birth Cohort.
• Measurement of prenatal PAH exposure using personal active samplers during the third trimester of pregnancy.
• Evaluation of microbiome diversity (alpha and beta) and differential abundance of taxa in 35 meconium samples based on PAH exposure tertiles (high vs. low/medium).

Main Results:

• While total PAH exposure did not significantly alter alpha diversity, specific PAHs showed varied associations. High exposure to benzo[a]anthracene (BaA) and chrysene (Chry) negatively correlated with alpha diversity, whereas low/medium exposure to benzo[a]pyrene (BaP) showed a positive correlation.
• After adjusting for birthweight and sex, high exposure to BaA, BaP, Chry, indeno[1,2,3-cd]pyrene (IcdP), and total PAHs was negatively associated with alpha diversity metrics.
• No significant differences in beta diversity were detected, but differential abundance analysis revealed specific bacterial taxa that varied between exposure groups.

Conclusions:

• In utero PAH exposure appears to alter gut microbiome alpha diversity and bacterial taxa abundance, suggesting a potential impediment to early microbial colonization.
• The findings, despite a limited sample size, provide preliminary evidence supporting the need for larger-scale research into the long-term health impacts of prenatal PAH exposure.
• Further investigation is warranted to elucidate the differential effects of specific PAHs on the developing infant gut microbiome and subsequent health outcomes.