Blood Lead Levels and Risk of Asthma Among a High-Poverty, Clinical Cohort of Children

To explore the association between peak blood lead levels (BLL) and subsequent asthma diagnosis in an urban clinical cohort of children who received health care through the Temple University Health System (TUHS) in Philadelphia, PA, between 2010 and 2020. We conducted a retrospective cohort study using electronic health record (EHR) data from TUHS. Eligible participants included all children aged < 18 years with at least one laboratory measured BLL (N = 14,217). Peak BLL (µg/dl) were extracted from laboratory test results in the EHR. Log-binomial regression models were fit to estimate the prevalence ratio (PR) and 95% confidence interval (CI) between BLLs and asthma diagnosis (via billing codes), adjusting for race, ethnicity, insurance, age at blood sample collection, and Social Deprivation Index (SDI). In our sample, 3488 participants were diagnosed with asthma, mostly male (57.37%) and Black race (59.78%). Among all children, approximately 27% had a peak BLL of ≥ 3.5 µg/dl. Children with a BLL of 1.0–3.4 µg/dl compared to those with a BLL < 1.0 µg /dl had a 81% (95% CI 1.46–2.25) increased risk of asthma diagnosis. No differences were observed for males and females. In this study, children with higher BLLs had an increased risk of asthma diagnosis. Importantly, associations were observed for children with BLLs below the current CDC-set action level. These findings indicate that decreasing environmental lead exposure has the potential to mitigate asthma risk in children, even among children with low-level exposure.