A new study documents racial disparities in childhood exposure to neurotoxic air

The researchers found Black and Hispanic children consistently exposed at the highest levels, exacerbating health and developmental inequalities.

By Sarah Steimer

Despite research on the developmental impacts of air pollution among young children, which have found that neurotoxic exposure is inversely related to their cognitive abilities, few studies have captured individual-level exposures to toxics circulating in the air, nor have they tracked how these hazards accumulate over time, particularly during the sensitive period of early childhood. But a new study published in the Journal of Health and Social Behavior revealed large racial disparities in exposure to neurotoxic pollutants from birth through kindergarten entry, with Black and Hispanic children consistently exposed at the highest levels.

University of Chicago researchers Geoffrey Wodtke, a Professor in the Department of Sociology and Associate Director of the Stone Center for Research on Wealth Inequality and Mobility, and Betsy Priem, a PhD Candidate of Sociology, along with Kerry Ard, Associate Professor of Environmental and Natural Resource Sociology at the Ohio State University, previously explored how environmental factors contributed to disparities in reading and math abilities. This prior research aimed to determine whether local environmental hazards created place-based gaps in school readiness.

Seeing major limitations in the literature around neurotoxic air pollution and race, the researchers seized an opportunity to use the same dataset to examine racial disparities in toxic exposure levels. They focused on estimating racial disparities in cumulative air pollution exposure throughout early childhood.

“Most studies on air pollution inequality are focused on adulthood or children aged 5 through 18,” Priem says. “So there's this really big gap in early childhood, where it's pretty well established in the health literature and health research that these are very formative years when pollution can interrupt the development and physical processes in your body, leading to negative impacts on the early emergence of cognitive abilities.”

The team used data from the U.S. Early Childhood Longitudinal Study, Birth Cohort (ECLS-B), which tracks a nationally representative sample of children from infancy through kindergarten entry. The researchers measured sample members’ exposure to a comprehensive set of neurotoxic pollutants in the air surrounding their homes at each wave of the study. They matched participants with concentration estimates for 52 air pollutants monitored by the EPA that are known or suspected to harm the central nervous system.

Priem notes that research has shown air pollution levels have come down for all racial groups; however, this decline did not mitigate racial disparities: some groups are still exposed at much higher levels than other groups. So while overall pollution fell, racial gaps persist.

The JHSB study compared average exposure levels for different racial groups over the first few years of life, rather than comparing specific locations across the U.S. The team then investigated how these disparities in exposure levels are related to socioeconomic differences among racial groups by estimating another set of exposure disparities using inverse probability weights and measures that account for intersectional inequalities. 

For example, the team looked at whether socioeconomic status explained disparities in exposure instead of race, but found that race was still the main driver. When they took race and socioeconomic status into account, they found that those who belong to a minority population and have lower socioeconomic status are exposed to the highest levels of pollution.

“It highlights this double-whammy effect, where, if you're disadvantaged in one social category and another, your exposure to pollution levels is also higher,” Priem says. “It speaks a lot to how the social infrastructure is creating environmental hazards in a way that compounds some of these disadvantages in society.”

The research team’s use of longitudinal data from a nationally representative sample of infants, their analysis of a broad spectrum of neurotoxics, and their efforts to parse out the relationship between race, class, and exposure to health hazards made their study a crucial development in understanding early-life disparities in pollution exposure.

Priem says that there is not yet data to speak to the consequences of what this exposure means, but indications of other research suggests that higher exposures to different toxics during critical developmental stages of life increases the potential for disruptions. She called the JHSB study a first step in establishing racial disparities in exposure levels during one such period—early childhood. 

“One of the key messages that we tried to explain toward the end of our paper was that it's not enough to just reduce the air pollution levels,” Priem explains. “That doesn't seem to actually address this racial disparity in terms of exposure to air pollution. Addressing some of the racialized structures that create the indifference in exposure levels in the first place would be where we think policymakers need to focus their attention.”