Soil pollution risk mapped
Science Magazine highlighted an analysis estimating up to 1.4 billion people could be exposed to toxic soil pollution—heavy metals like arsenic and lead—with a newly identified high‑risk zone in low‑latitude Eurasia. (x.com) The Science post itself recorded about 508 likes and 43,000 views as the findings circulated online. (x.com)
A global analysis published in *Science* found toxic metals in 14% to 17% of cropland, with up to 1.4 billion people living in higher-risk areas. (science.org) Soil pollution in this case means metals such as arsenic, cadmium, chromium, nickel, and lead building up in farmland at levels above agricultural or health thresholds. The researchers compiled 796,084 soil measurements from 1,493 regional studies and used machine learning to map where those thresholds are exceeded. (science.org) The paper was published online on April 17, 2025, led by Deyi Hou of Tsinghua University with co-authors from China, the United Kingdom, the United States, and Norway. Their estimate puts about 242 million hectares of cropland above agricultural thresholds for at least one of seven toxic metals. (science.org) (tsinghua.edu.cn) The map also identified a high-risk belt in low-latitude Eurasia, spanning southern Europe, the Middle East, South Asia, and southern China. The authors linked that pattern to a mix of climate, terrain, mining, industry, and long-term human land use. (science.org) (rothamsted.ac.uk) The problem is not just dirt chemistry. Metals in soil can move into crops, livestock, water, and dust, and the *Science* paper says soil underpins nearly 95% of the food humans consume. (science.org) The study found cadmium had the highest global exceedance rate at 9.0% of surficial soils, with hotspots in northern and central India, southern China, and South Africa. Nickel and chromium exceedances were concentrated in parts of the Middle East, subarctic Russia, and eastern Africa. (tsinghua.edu.cn) Researchers said some contamination comes from bedrock weathering, which is natural, and some comes from mining, smelting, fertilizers, wastewater irrigation, and other industrial activity. That mix helps explain why heavily farmed and heavily industrialized regions can overlap with naturally metal-rich zones. (science.org) (soci.org) The authors also cautioned that mapped hazard is not the same as measured human dose. Actual harm depends on how mobile the metal is, whether crops absorb it, and how people are exposed through food, water, or inhaled dust. (soci.org) (science.org) That uncertainty cuts both ways: the paper says global coverage is still uneven, especially in low-income regions where soil sampling is sparse. The map is a first worldwide baseline, not a final count of every contaminated field. (science.org) (datadryad.org) What the new map changes is scale. Instead of isolated local studies, it gives governments a global screening tool for where to test soil, track food contamination, and target cleanup before toxic metals move further through the food chain. (science.org) (rothamsted.ac.uk)
