PROTECT Researchers Find that Chemicals Detected at Higher Levels in Non-Hispanic Black Women Impact Preterm Birth Genes

The disproportionate rate of preterm birth in non-Hispanic Black women is well-documented. The exposure to certain environmental chemicals that non-Hispanic Black women face compared to non-Hispanic White women is also well-documented. A recent publication lead by Project 2 leader Sean Harris reports on researchers’ efforts to use statistical analysis to determine which chemicals may contribute to the racial disparities observed in preterm birth.

The process to understand the mechanisms of preterm birth in relation to certain environmental contaminants included the use of publicly available databases. Investigators used these databases to identify chemicals detected at higher levels in non-Hispanic Black women than non-Hispanic White women. Researchers then accessed a list of interactions of different chemicals and contaminants in the Comparative Toxicogenomics Database (CTD). They then ran statistical tests for each of the identified chemicals to see if they interacted with genes involved with preterm birth more than would be expected by random chance.

The statistical analysis showed that a diverse set of chemicals detected at higher levels in non-Hispanic Black women had significantly high numbers of interactions with genes that are involved in preterm birth. These chemicals included metals, phthalates, polychlorinated biphenyls (PCBs), pesticides, personal care products, and perfluorinated alkyl substances. That a diverse set of chemicals targets preterm birth genes suggests that exposure to multiple environmental toxicants may drive the racial disparities in preterm birth rather than one isolated chemical or chemical group. This highlights the complexity of understanding the mechanistic pathways through which toxicant exposures influence adverse pregnancy outcomes.

Chemical-gene interactions for 90 genes in three key Gene Ontology terms for chemicals detected at higher levels in non-Hispanic Black women.
Pathway enrichment analysis for chemicals detected at higher levels in non-Hispanic Black women compared to non-Hispanic White women.

Race and ethnicity as constructs connect to multiple societal, cultural, and environmental factors that likely play a role in differing patterns of exposure. One of these factors is environmental racism, such as historical residential segregation. Studies have found that Black mothers live near soil with high distribution of lead and arsenic more often than White mothers. Both contaminants were found to be enriched with preterm birth genes in Harris et al.’s analysis. Racialized beauty standards can also play a role in exposure differences. Some products advertised only to Black women contain chemicals that were found to target preterm birth genes in this study. Oftentimes, these chemicals are not listed on product labels, leading to an information gap for consumers who seek to limit their chemical exposures. Since several forces potentially contribute to racial disparities in chemical exposure, it’s important that researchers use multidisciplinary approaches, like the one used here that combines exposure data and molecular evaluation, when investigating preterm birth.

The research methods used in this study show how different data sources can be utilized together to study the mechanisms of adverse pregnancy outcomes. The kind of exposure data collected by PROTECT can be used with public toxicology and disease databases to identify environmental toxicants that may impact adverse pregnancy outcomes. The design of this study can also be used to inform future toxicology studies. PROTECT scientists can apply the methods developed here to investigate the chemical mixtures specific to the environment of Puerto Rico and the Superfund sites on the island.

For detailed results and further discussion, you can read the full paper here.