The birthweight toll of mining pollution: evidence from the most contaminated mine site in the Andean region.

Abstract

To assess the effect of mining pollution on birthweight. A retrospective before-and-after study with an untreated comparison group. La Oroya, a mining town in the Peruvian Andes, considered the most contaminated town in the Andean region. All pregnant women who delivered in the social security healthcare system in years 2005, 2006, 2008 and 2009. A total of 214 983 births records were used, 957 from La Oroya and 214 026 from the rest of the country. A difference-in-difference estimation is used to assess the effect of mining pollution on birthweight before and after two business policy changes: a partial environmental improvement and a subsequent closure of smelter operations in La Oroya. Birthweight was compared with a group not affected by the environmental changes in La Oroya. Birthweight in grams. A steep reduction in mining pollution due to the closure of smelter operations in La Oroya showed an increased birthweight of 71.6 g after controlling for socio-economic and medical characteristics. None of the environmental improvements prior to the closure had a statistically significant effect on birthweight. Mining pollution in La Oroya had a negative impact on birthweight. Partial environmental improvements were not enough to improve birthweight. Only after the closure of all mining and smelter operations in La Oroya was a significant gain in birthweight shown. The closure of the most contaminated mine site in the Andean region increased birthweight by 72 g.