The Long-term Effects of Early Lead Exposure: Evidence from a case of Environmental Negligence
This paper estimates the effect of early lead exposure on academic achievement and adult earnings. We analyze longitudinal information from individuals attending primary and secondary schools in the city of Arica (in northern Chile). Between 1984 and 1989, Arica received more than 20,000 tons of toxic chemicals containing high concentrations of lead. Initially, the chemical waste was located several kilometers from the city. However, Arica's rapid expansion, which included the construction of housing projects just meters away from the waste deposit, put a large number of families at risk. Our data include information on residential proximity to the polluted area, levels of lead exposure, comprehensive demographic information, nationally representative academic test scores and administrative data on adult earnings.
We document a strong relationship between blood lead levels and student academic performance. We find that an increase of one microgram of lead per deciliter of blood reduces math and language scores by 0.15 and 0.21 standard deviations, respectively. For earnings, we estimate that for each extra microgram of lead, monthly earnings decrease by CLP 11,458 (or USD 22.92). This translates into a reduction of USD 6,000 in lifetime earnings per microgram of lead per deciliter of blood.
We have benefitted from the discussion with Orly Ashenfelter, Lori Beaman, David Card, Brian Jacob, Pat Kline, Fabian Lange, Giordano Palloni, Jeff Smith, Duncan Thomas, and comments from seminar participants at Duke University, Aarhus Universitet, NBER Summer Institute, University of California-Berkeley, Northwestern University, University of Michigan, University of Maryland, University of Chile, Pontificia Universidad Católica de Chile, Universidad Adolfo Ibáñez, Universidad Diego Portales, XV Annual Meeting of the Latin American and Caribbean Economic Association LACEA - 2010 (Medellín, Colombia), National Environmental Commission of Chile (Comisión Nacional de Medio Ambiente, CONAMA), the XVI Annual Meeting of the Network on Inequality and Poverty NIP - 2011 (Cuernavaca, México) and the Northeast Universities Development Consortium Conference 2011 (NEUDC). We thank the team of the TV show "Contacto'' for some of the data analyzed in this paper. We also thank Andrei N. Tchernitchin for his guidance on the medical literature documenting the effects of lead on humans. Tomas Rau and Sergio Urzúa thank the support of Centro de Microdatos at the University of Chile through the Millennium Science Initiative sponsored by the Chilean Ministry of Economics, Development and Tourism, Project NS100041. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research.