Black Children in Racially Isolated Neighborhoods Have Higher Lead Exposure

Black children who live in racially isolated neighborhoods are more likely to be exposed to higher levels of lead, according to study findings published in the journal Pediatrics.

Childhood lead exposure is an established risk factor for learning deficits and lower standardized test scores. This exposure is a critical environmental marker of health disparities, as contaminants are often found in areas where individuals who are low-income and people of color live. Researchers conducted a population-based observational study to assess the association between childhood blood lead levels and racial residential segregation.

The researchers collected blood lead testing data from the North Carolina Department of Health and Human Services between the years 1992 to 1996 and 2013 to 2015. In North Carolina, all children in Medicaid or the Women, Infants, and Children (WIC) Program have a testing requirement at ages 1 and 2.

The researchers restricted the dataset to patients aged younger than 7 years at the time of testing and to individuals who were non-Hispanic Black or non-Hispanic White due to the small sizes of other racial and ethnic groups.  

A total of 320,916 lead blood testing results from 100 North Carolina counties were included in the analysis, with 154,366 records from 1992 to 1996 and 166,550 records from 2013 to 2015. 

The researchers developed a measure of racial isolation among the non-Hispanic Black (RI_NHB) population and compared it to other racial groups. The score measured how segregated neighborhoods within a census tract were based on race. The RI_NHB score ranges from 0 to 1, with higher values indicating higher levels of isolation and more non-Hispanic Black individuals living in that area.

There was a 50% increase in RI_NHB from 1990 to 2015, among 2195 North Carolina census tracts. From 1992 to 1996, the blood lead testing data revealed that a 1-standard deviation increase in RI_NHB was associated with a 2.86% (95% CI, 0.96%-4.81%) increase in blood lead levels in non-Hispanic Black children and a 2.44% (95% CI, 1.34%-3.56%) increase among non-Hispanic White children.

From 2013 to 2015, the researchers found that with a 1-standard deviation increase in RI_NHB, there was an associated increase of 1.59% (95% CI, 0.50%-2.70%) in blood lead levels among non-Hispanic Black children and a 0.76% (95% CI, 0.08%-1.45%) increase among non-Hispanic White children. 

“[R]acial residential segregation continues to drive higher levels of childhood lead exposure among Black children in the United States,” the researchers wrote.

They added, “The RI_NHB index and measures of its change over time and geography are meant to shift the debate around disparities from using race, a nonmodifiable factor, as an explanatory variable, to the experience of racial minorities, which is modifiable, as a key driver of disparities.” 

Study limitations include the exclusion of other ethnic minority populations, the inability to account for all factors contributing to segregation based on one score, and a lack of generalizability.