Heavy metals contaminate up to 17 percent of world‍‍`s arable land

Up to 17 percent of the world’s arable land is contaminated with toxic heavy metals, potentially endangering the health of up to 1.4 billion people — according to a new global study published in the journal Science. This research, led by Deyi Hou of China’s Tsinghua University, represents the first comprehensive global overview of soil contamination by heavy metals, using a meta-analysis of nearly 800,000 soil samples collected worldwide.

The team carefully verified the data’s reliability by excluding samples known to be taken from already contaminated sites and applied machine learning algorithms to pinpoint the areas facing the greatest risk. The analysis focused on seven hazardous metals — arsenic, cadmium, cobalt, chromium, copper, nickel, and lead — assessing where their concentrations exceeded internationally recommended safe limits for agriculture and human health.

The findings reveal that between 14 and 17 percent of cropland globally contains levels of these metals beyond safety thresholds. Heavy metals can spread through food chains and water systems, posing threats to people, animals, and plants alike. The study estimates that between 900 million and 1.4 billion people live in areas considered to be at high risk from such contamination.

Heavy metal pollution can originate both from natural geological processes and from human activities like mining, industrial waste disposal, and intensive agricultural practices. However, researchers noted gaps in available data — particularly across Africa — which limit the ability to create targeted risk-reduction strategies for certain regions.

The authors emphasized that their work is meant as a scientific warning for governments, policymakers, and farmers to take swift and necessary action. Soil chemist Wakene Negassa of the James Hutton Institute, commenting on the study, cautioned that the actual extent of global soil contamination might be even higher than reported, due to limited data and likely underestimation in many parts of the world.