My current research focuses on ways to reduce the impact of the environment on human health. For two decades, I coordinated earth-science and mitigation efforts under Columbia’s Superfund Research Program on the origin and health effects of elevated levels of arsenic in groundwater. A theme that runs through this and other ongoing projects, e.g., concerning fluoride in groundwater in India, bauxite dust in Guinea, or soil contaminated with lead from mine-tailings in Peru, is that patterns of contamination are spatially very heterogeneous. This complicates prediction but often also points the way to mitigation when the hazard can be mapped. For this reason, I am a firm believer in the more widespread use of field kits by non-specialists to reduce exposure to environmental toxicants, particularly in developing countries. I collaborate with public health and social scientists to evaluate how such kits can be deployed at scale and have published over 180 peer-reviewed papers on this and other environmental topics. I hold a research professor appointment at Lamont-Doherty Earth Observatory and am a member of the Earth Institute faculty at Columbia University.