By applying multiple causal inference approaches, this study provides robust evidence that lead exposure impairs selective attention in school-age children, with detrimental associations amplified among those sleeping ≤8 hours.
A doubling of blood lead levels was associated with lower Stroop Color Test scores in models adjusted for both generalized propensity scores and potential confounders.
A doubling of blood lead levels was associated with lower Stroop Color-Word Test scores, reflecting impaired selective attention.
The association between blood lead levels and impaired selective attention was stronger among children sleeping ≤8 hours compared to those sleeping longer.
Generalized propensity scores (GPSs) were generated using linear regression models predicting lead levels to support causal inference.
Blood lead concentrations in early childhood were associated with impaired selective attention as measured by both the color and color-word components of the Stroop test.
This research suggests that higher blood lead levels in early childhood are linked to poorer selective attention in school-age children. Selective attention — the ability to focus on relevant information while ignoring distractions — is critical for learning and self-regulation. The study followed 377 Korean children from ages 6 to 10, measuring their blood lead levels and testing their attention using the Stroop Color and Word Test, which requires children to name the color of ink while ignoring the written word. Using advanced statistical methods designed to approximate the strength of evidence from a controlled experiment, the researchers found that each doubling of blood lead concentration was associated with meaningfully lower test scores on both the color naming and color-word components of the Stroop test. The study also found that sleep duration appears to modify how harmful lead exposure is for attention. Children who slept 8 hours or fewer showed a stronger negative association between lead levels and attention scores compared to children who slept more than 8 hours. This suggests that getting adequate sleep may help buffer some of the harmful effects of lead on brain development, though the study cannot prove that sleep itself directly causes this protection. This research matters because it adds to growing evidence that even low-level lead exposure — at concentrations commonly found in children today — can harm cognitive development. The use of multiple causal inference methods makes these findings more robust than typical observational studies. The interaction with sleep duration is a novel finding that points to sleep as a potentially important factor in children's neurological resilience, and highlights the importance of both reducing environmental lead exposure and ensuring children get sufficient sleep.
Jang H, Shin C, Lee Y, Lee Y, Lim Y, Hong Y, et al.. (2026). Early childhood blood lead concentrations and selective attention among school-age children: Evidence consistent with a causal association and effect modification by sleep duration.. Ecotoxicology and environmental safety. https://doi.org/10.1016/j.ecoenv.2026.119845