What Are the Effects of Early-Childhood Exposure to Environmental Lead on Personality

In the first statistical analysis examining links between pollution and personality, Schwaba et al. (2021) leveraged a natural experiment driven by the US Clean Air Act to estimate effects of reduced atmospheric lead on the "big five" personality traits-extraversion, agreeableness, conscientiousness, neuroticism, and openness to new experiences. Using data from an online personality test taken by more than 1.2 million US residents, Schwaba et al. found that people born after atmospheric lead levels in their county of birth had peaked had more mature, psychologically healthy personalities in adulthood (higher agreeableness and conscientiousness, and lower neuroticism) than cohorts born earlier and exposed to higher levels of atmospheric lead. One concern with their findings is that changes in personality across people born in different periods could come from factors unrelated to lead, such as access to abortion and birth control, or demographic, cultural, or technological changes. Schwaba et al. recognized this possibility but did not fully explore it. When we account for cohort-wide changes using birth-year fixed effects in Schwaba et al.'s models, the estimated effects of the lead phaseout on personality largely disappear. The estimated effects fall substantially in magnitude, becoming indistinguishable from zero while remaining precise. Meanwhile, estimated birth-year fixed effects are jointly significant, suggesting differences in personality traits across cohorts. Our results do not imply an overstatement in estimates of the quantifiable benefits of reducing childhood exposure to lead, which are based on the economic value of gains to IQ, but they do suggest that any personality effects of the lead phaseout are not consistently observable in the data used by Schwaba et al.

Arthur G. Fraas

Visiting Fellow

Arthur Fraas is a visiting fellow at Resources for the Future. At RFF, Fraas works on a variety of issues related to energy and the environment, including projects looking at issues and tradeoffs with energy efficiency regulations, and more.

Randall Lutter

Senior Fellow, Manhattan Institute

Joshua Murphy

Senior Economist, Natural Resources Canada

Qinrui Xiahou

PhD Candidate, University of Hong Kong

Jeff Porter

Chief Technology Officer, Enveritas

Samuel D. Gosling

Professor, University of Texas, Austin

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