Early Childhood Lead Exposure and the Persistence of Educational Consequences into Adolescence

There is consensus that early childhood lead exposure causes adverse cognitive and behavioral effects, even at blood lead levels (BLL) below 5 µg/dL. What has not been established is to what extent the effects of childhood lead exposure persist across grades. In this paper, we examine data from 538,493 children living in North Carolina between 2000-2012 with a BLL ≤ 10 µg/dL to estimate the effects of early childhood lead exposure on educational performance from grades 3-8, to determine if effects in lower grades persist as a child progresses through adolescence. We estimate fixed-effects models and use socio-economic and demographic information along with coarsened exact matching techniques to control for confounding effects to identify the causal effect of BLL on test performance. We find that the effects of early childhood exposure to low lead levels caused persistent deficits in educational performance across grades. In each grade (3-8), children with higher blood lead levels had, on average, lower percentile scores in both math and reading than children with lower blood lead levels. In our primary model, we find that children with BLL = 5 µg/dL in early childhood ranked 1.50 – 2.07 (1.94 – 2.43) percentiles lower than children with BLL ≤ 1 µg/dL on math (reading) tests during grades 3-8. As children progressed through school, the average percentile deficit in their test scores remained stable.