Historical Redlining and Racial Disparities in Child Blood Lead Levels in Southeastern Wisconsin.

Historical redlining originated in the 1930s from the Home Owners’ Loan Corporation (HOLC), with discriminatory loans and insurance based on neighborhoods’ racial/ethnic composition and socioeconomic status. We investigated associations between historically redlined neighborhood grades and child blood lead levels (BLL), and whether these associations differed by race/ethnicity. Child BLL, demographic, and geocoded home address data were collected from the Wisconsin Systematic Tracking of Elevated Lead Levels and Remediation system in Milwaukee and Racine Counties (1996–2001, 2011–2020). We analyzed 26,381 unique BLL in adjusted linear regression models, explored interactions of HOLC grade and race/ethnicity on BLL, and assessed spatial autocorrelation. Most children were Black (70%) or Latino/a (11%). Median (Q1, Q3) values for age were 2.9 years (1.8, 4.4), and BLL were 11.0 μg/dL (9.0, 15.0). There was a gradient of increasing BLL as HOLC grades worsened from “no grade” to C/D grades. In models adjusted for race/ethnicity and age, BLL had associated increases by 2.39 μg/dL (95% CI 2.11, 2.66) and 2.37 μg/dL (95% CI 2.08, 2.66) among children in HOLC C and D, respectively, compared to “no grade.” Interaction models showed Black children had substantially higher mean BLL independent of HOLC grade compared to non-Black children (p-interaction: < 0.0001). BLL increased with worsening HOLC grades. There was also clear evidence of stronger associations between HOLC grade and BLL among Black children, exemplifying the importance of race on BLL. This study examined present-day BLL disparities relative to historical redlining and highlighted the persistence of disproportionate racial/ethnic environmental exposures.