Metals and metalloids are ubiquitous in soils, originating from bedrock and from human activities and infrastructure. These compounds can be toxic to humans and other organisms, and their soil distribution and concentrations at global scale are not well known.

Hou et al. analyzed data from more than 1000 regional studies to identify areas of metal toxicity and explore drivers of these trends. They estimate that 14 to 17% of cropland exceeds agricultural thresholds for at least one toxic metal.

Climate and topography, along with mining activity and irrigation, predicted which soils would exceed metal thresholds. Soil metal pollution is a global issue that will likely increase with the growing demand for toxic metals in new technologies.