Environmental lead exposure and clinical infectious respiratory disease in a sample of urban and disadvantaged children

Abstract Background Early-life environmental lead exposure can adversely impact the development of the immune system and increase the susceptibility to infectious respiratory illnesses, but evidence regarding childhood respiratory outcomes remains inconclusive. Objective To examine the association between childhood blood lead concentrations and diagnosis of streptococcal pharyngitis or croup in an under-resourced, low-income sample of children residing in Philadelphia, PA. Methods This retrospective cohort study included medical record data on 13,221 children ≤14 years as part of the Temple University Health System from 2010 to 2020. Lead exposure was measured via blood lead concentration (BLC), and infections were identified using ICD codes. Covariates included age at blood lead collection, sex, race, ethnicity, and insurance type. Logistic and Poisson models estimated associations between BLC and strep or croup and the frequency of outcomes, respectively, with sex-stratified analyses to assess potential effect modification. Results Among participants, 28% had BLCs above the Centers for Disease Control and Prevention (CDC) action level of 3.5 µg/dL. There were higher odds of BLC ≥ 3.5 µg/dL (aOR: 2.74, 95% CI: 1.92, 3.90) and BLC 1–3.4 µg/dL (aOR: 2.45, 95% CI: 1.75, 3.44) among children with strep compared to those without a strep diagnosis. Higher risk of frequent strep diagnosis was observed for those with BLC ≥ 3.5 µg/dL (aRR: 2.65, 95% CI: 1.89, 3.70) and BLC 1–3.4 µg/dL (aRR: 2.39, 95% CI: 1.73, 3.30). No associations were observed between BLC and croup diagnosis. Significance Findings suggest evidence of an association between BLC and strep, even at levels below the current action level, supporting the conclusion that no level of lead exposure is safe. BLCs below current CDC reference levels may still have clinically relevant health implications among children. The results underscore the potential impact of environmental lead exposure on biological vulnerability during childhood among a population facing social and structural inequities. Impact statement This study responds to a critical gap in the literature on the relationship between environmental lead exposure in early childhood and common pediatric respiratory infections. The examination of lead exposure in association with streptococcal pharyngitis and croup in an under-resourced pediatric sample underscores the joint impact of biological vulnerability in childhood and social disadvantage on health outcomes. Our findings contribute to evidence for the need to revise policies regarding environmental lead toxicant exposure and confront structural barriers in the effort to protect the trajectory of children’s health.