How Did Lead Exposure Affect the Children of the '70s?

March 28, 2017

How Did Lead Exposure Affect the Children of the '70s?

  1. John D. Cowden, MD, MPH

Greater childhood lead exposure was associated with lower adult IQ and socioeconomic status at age 38, though effects were small.

  1. John D. Cowden, MD, MPH

Lead exposure has been linked to lower IQ in children and adolescents, but effects later in life have not been studied on a large scale.

Researchers reported on 565 individuals from a 1972–73 New Zealand birth cohort whose blood lead level had been measured at age 11 years. At age 38 years, IQ was reassessed and socioeconomic status scored by job type using a standard national formula (range [low to high], 10 to 90). Adjustments were made for child and maternal IQ, as well as childhood socioeconomic status.

Blood lead levels ranged from 4 to 31 μg/dL, with a mean of 11 μg/dL. Forty-six percent of children had levels >10 μg/dL. After adjusting for potential covariates, every 5-μg/dL increase in blood lead level at age 11 was associated with a 1.61-point lower IQ score and a 1.79-unit lower socioeconomic status score at age 38. Blood lead level >10 μg/dL was associated with a 2.73-point lower mean adult IQ score and a 3.42-unit lower mean adult socioeconomic score compared with blood lead level ≤10 μg/dL. Forty percent of the association between childhood lead exposure and decline in socioeconomic status from childhood to adulthood was mediated by IQ decline.


Though these differences in IQ and socioeconomic status are small from the clinical perspective, the cumulative impact of childhood lead exposure could be significant, given the widespread exposure that occurred in the 1970s and '80s. We might question whether these results are relevant today, when broad lead exposure is less common, but the recent Flint water crisis and ongoing regional lead contamination (such as in Missouri, where I practice) show that we remain in a perilous situation regarding childhood lead toxicity. Vigilance, rather than complacency, must define our approach to public health policy and pediatric care through not only testing but also aggressive lead abatement strategies.

Editor Disclosures at Time of Publication

  • Disclosures for John D. Cowden, MD, MPH at time of publication Leadership positions in professional societies Co-Chair, Culture, Ethnicity, and Health Care Special Interest Group, Academic Pediatric Association


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