Glyphosate Use, Water Contamination, and Neonatal Health in the United States (Revise & Resubmit, Journal of the Association of Environmental and Resource Economists) [PDF]

Abstract. This study investigates the impact of glyphosate, the most widely used herbicide, on birth outcomes in the US Corn Belt. Using water flow mechanisms to identify causal effects, the study shows that glyphosate affects populations far from application sites through waterborne transmission. The results suggest that a 10 kg/km2 increase in upstream glyphosate use led to a 4.6 percent rise in neonatal deaths in lower-income areas, with no observed effects in higher-income regions. The research design also incorporates variations in spatial distances, seasonal exposure patterns, and rainfall data to ensure that the observed health impacts are attributable to glyphosate. Evidence suggests avoidance behaviors and water treatment are potential mechanisms of the heterogeneous effects.

Using Vegetable Oils for Biofuel Accelerates Forest-to-Palm Land Conversion (with Aaron Smith, Richard Sexton. In preparation for submission)

Abstract.    Biofuels are promoted worldwide as a strategy to cut greenhouse gas emissions, yet their climate benefits are uncertain because of induced deforestation. We show that global demand for biomass-based diesel fuel between 2002 and 2018 drove the conversion of approximately 1.7 million hectares of forest to oil palm in Indonesia and Malaysia, which is about one-fifth of the total forest-to-palm expansion during this period. Using econometric models and high-resolution remote sensing data, we demonstrate that biomass-based diesel demand raised palm oil prices, which in turn accelerated deforestation, primarily in natural forests. The associated land-use change released more than one gigaton of CO2, giving palm-based biodiesel higher carbon emissions per megajoule than that of fossil diesel. These findings indicate that biofuels derived from vegetable oils have likely increased, rather than reduced, global emissions, and highlight the urgent need to shift renewable fuel policies away from crop-based feedstocks.