Environmental Exposure Disparities and Neurodevelopmental Risk: a Review

Abstract

Purpose of review: Neurotoxicant exposures are of particular concern in historically marginalized communities. Often a consequence of structural racism, low-income minoritized populations experience a disproportionate burden of hazardous exposures through proximity to industrial facilities, high traffic roads, and suboptimal housing. Here, we summarize reports on exposures and neurodevelopment focused on differences by education, income, race/ethnicity, or immigration status from 2015 to 2022, discuss the importance of such investigations in overburdened communities, and recommend areas for future research.

Recent findings: We found 20 studies that investigated exposure disparities and neurodevelopment in children. Most were conducted in the USA, and many focused on air pollution, followed by metal exposures and water contamination. Although several studies showed differences in exposure-outcome associations by income and education, many examining differences by race/ethnicity did not report notable disparities between groups. However, measures of individual race and ethnicity are not reliable measures of discrimination experienced as a consequence of structural racism. Our review supports scientific evidence that the reduction of individual and widespread municipal exposures will improve child development and overall public health. Identified research gaps include the use of better indicators of economic status and structural racism, evaluations of effect modification and attributable fraction of outcomes by these factors, and considerations of multidimensional neighborhood factors that could be protective against environmental insults. Considering that vulnerable populations have disparities in access to and quality of care, greater burden of exposure, and fewer resources to incur associated expenses, such populations should be prioritized.

Keywords: Behavioral problems; Cognitive function; Environmental justice; Environmental pollutants; Exposure disparities; Neurodevelopment.

Fig. 1

Article search and selection method utilized in reviewing studies on the associations between environmental exposures and neurodevelopmental outcomes by race and socioeconomic status or in low- and middle-income countries. Solid lines represent articles included and dashed lines denote excluded articles. The fnal search included articles published between January 1, 2015 and July 1, 2022

Fig. 2

Number of articles included in the review by year (20 total articles)

Fig. 3

Heat map of included studies by neurodevelopmental outcome, environmental exposure category, and demographic characteristic. Exposure categories by demographic characteristics are in rows and neurodevelopmental outcomes are in columns. Numbers within cells are the number of studies meeting each exposure-outcome-demographic combinations. An interactive version of this figure is available at https://public.tableau.com/authoring/EnvExpDisparties_Neurodevelopment/Dashboard#1. Each exposure category is broken down into specific exposure in the box below the figure. Tabulations for types of study design are described for each combination block. Information on each study included is provided at the bottom right corner of the interactive figure, including firth author and year, title of the manuscript, study design, population, study sample, exposure measurement, outcome measurement, covariates, results, URL link to find the manuscript, and citation information