Early Exposure to Hazardous Waste and Academic Achievement: Evidence from a Case of Environmental Negligence
Numerous studies have indicated that exposure to heavy metals can cause irreversible harm in the early development of cognition, but less is known about the longer-run effects of such exposure. Professor Sergio Urzúa and his colleagues investigate these effects using data on residents of a community in northern Chile who were exposed to heavy metals that had been stockpiled for use in the mining industry. The waste was stockpiled between 1984 and 1989. Over the next several years, perhaps reflecting a lack of awareness of the nature of the materials being stockpiled, the government completed construction of two large housing projects near the site. Lead levels in the surrounding community were documented on numerous occasions from 1996 to 2009.
Using the results of tests done on residents in the vicinity of the waste site, Rau, Urzúa, and Reyes show that living closer to the toxic waste site was associated with significantly higher blood lead levels. To assess the effects of this lead exposure on school performance, the authors look first at scores on the standardized tests taken by fourth-grade Chilean students. They find that students in schools located closer to the site had scores on these tests that were significantly lower than those of students with similar backgrounds attending schools located further away. Prior to the stockpiling, this had not been true, suggesting that the result is not attributable to other differences between the schools. Further, the authors find, among students taking college entrance exams two decades later, those living more than 1 kilometer away from the site did significantly better than those living closer. Data from unemployment insurance records show that lower test scores are associated with lower salaries later in life. Based on this association, those growing up near the waste site may have lost, on average, $60,000 (USD) in lifetime wages due to the exposure.
Recent revelations of high lead levels in the drinking water of Flint Michigan have drawn renewed attention to the negative effects of heavy metal toxicity. The results provide a baseline to show how exposure to heavy metals can have large long lasting effects.
Rau, Tomás, et al. “Early Exposure to Hazardous Waste and Academic Achievement: Evidence from a Case of Environmental Negligence.” Journal of the Association of Environmental and Resource Economists, vol. 2, no. 4, 2015, pp. 527–563.