Inequalities in Exposure to Ambient Air Neurotoxicants and Disparities in Markers of Neurodevelopment in Children by Maternal Nativity Status

Abstract

Exposure levels to environmental pollutants vary significantly among different populations. These inequities in exposure to hazardous air pollutants (HAP) among different populations can contribute to disparities in neurodevelopmental outcomes. The aim of this study was to determine if exposure to HAP varies by maternal nativity status, a demographic marker often overlooked in the study of health disparities. We also assessed if those inequalities in exposure levels are associated with neurodevelopmental measures in young children. To do this, we obtained data from the Early Childhood Longitudinal Study-Birth cohort (ECLS-B), a nationally representative sample of children born in the U.S. in the year 2001 (N = 4750). Bayley’s Short Form-Research Edition (BSF-R) was used to measure cognitive development at 2 years of age. Using residential location at nine months of age, participants were assigned exposures to ten HAPs identified as potentially neurotoxic. Linear regression models were used to assess the joint effect of maternal nativity status and HAP exposure on neurodevelopment. Results showed inequities in exposure levels to ten different HAPs among the populations, as approximately 32% of children of foreign-born mothers were exposed to high levels of HAPs, compared to 21% of children born to U.S.-born mothers. Adjusting for socioeconomic factors, both isophorone exposure (a marker of industrial pollution) (−0.04, 95% CI, -0.12, 0.04) and maternal nativity status (−0.17, 95% CI, −0.27, −0.06) were independently associated with lower standardized BSF-R mental scores in children. Interaction between nativity status and isophorone was not statistically significant, but the change in mental scores associated with isophorone exposure was greater in children of foreign-born mothers compared to children of U.S.-born mothers (−0.12, vs. −0.03, p = 0.2). In conclusion, exposure to HAPs within the highest quartile was more commonly found among children of foreign-born mothers as compared to children of US-born mothers, indicating inequities in pollutant exposure by nativity status within urban populations. Exposures associated with nativity status may negatively contribute to children’s neurodevelopment.

The Intersection of Immigrant and Environmental Health: A Scoping Review of Observational Population Exposure and Epidemiologic Studies

“…We identified 17 total studies that analyzed immigrant disparities in exposure to or health effects from air pollution. 57 – 73 Of the 17 studies, 12 were based in the United States and 5 in Canada. These studies often found that immigrants or areas with higher immigrant proportions had higher exposures to air pollution compared with nonimmigrants or areas with lower immigrant proportions.…”

“…In the United States, there was a range of small area-level studies and large regional studies with individual data that found disparities in exposures to monitored black carbon (BC) 72 and ozone ( ), 68 as well as model-predicted fine particulate matter ( ) 61 , 63 , 65 , 73 and hazardous air pollutants (HAPs). 57 , 66 , 67 , 69 HAPs are 187 toxic air chemicals, including benzene, perchloroethylene, and methylene chloride, on a list maintained through the U.S. Environmental Protection Agency’s (EPA) 2011 National Air Toxics Assessment. 74 In California, an area-level study found that communities with high immigrant Vietnamese populations had higher BC levels compared with the statewide mean BC concentrations.…”

“…Four studies in the United States investigated immigrant exposure disparities to HAPs. 57 , 66 , 67 , 69 In Miami, Florida, Hispanic immigrants were exposed to a larger number of HAPs than nonimmigrant Hispanics and nonimmigrant populations of other ethnicities. 67 A separate national analysis with aggregated U.S. Census demographic estimates for each of 12,516 school districts concluded that the proportion of immigrant children in a school district was positively associated with higher levels of HAPs.…”

“… 69 In the national Early Childhood Longitudinal Study, 32% of the children of immigrant mothers were exposed to the highest quartile of HAPs compared with 21% of children of nonimmigrant mothers. 57 A recent study investigated multigenerational immigrant trajectories in exposure to among third-grade schoolchildren. 65 Immigrant schoolchildren and nonimmigrant schoolchildren with two immigrant parents had significantly higher exposures than nonimmigrant schoolchildren with at least one nonimmigrant parent.…”

“…Six studies investigated the disparities between immigrants and nonimmigrants in health effects resulting from air pollution exposure. 57 , 59 , 62 , 64 , 70 , 73 A study based in the San Joaquin Valley in California investigated the relationship between air pollution exposure to expectant Hispanic mothers and neural tube defects (NTDs) in their newborns. 70 Although NTDs were more prevalent among those born to Hispanic immigrant mothers than U.S.-born Hispanic mothers, carbon monoxide, nitrogen oxide, and exposures were more strongly associated with NTDs among nonimmigrant mothers than among immigrant mothers.…”