Four decades of global cereal lead contamination patterns

Lead contamination in cereal grains poses significant risks to global health, yet comprehensive assessments of pollution patterns and policy effectiveness remain limited. We analyzed 2843 lead data records from 59 countries spanning 1979-2023, employing the Benchmark Dose approach to evaluate spatiotemporal pollution trends and health risks. Our analysis indicates that while global lead concentrations have generally declined following the phase-out of leaded gasoline, regional pollution hotspots remain striking. Specifically, extremely high median lead burdens were identified in rice from Pakistan (0.40 mg/kg), wheat from Slovenia (1.33 mg/kg), and corn from India (1.02 mg/kg). Furthermore, median lead concentrations in specific regions of China (e.g., Chongqing and Fujian), Bangladesh, and Iran persisted between 0.20 and 0.83 mg/kg, sharply contrasting with the low levels (<0.01 mg/kg) maintained in many developed nations. Industrial activities, particularly battery manufacturing and metal smelting, have superseded gasoline as primary contemporary pollution sources, with per capita income showing a significant negative correlation with pollution levels (r = -0.32 to -0.41). Health risk assessments reveal concerning exposure levels for children; Margins of Exposure fell below 1 in multiple countries, indicating potential neurodevelopmental risks from cereal consumption alone. This study underscores that while the elimination of leaded gasoline represents a success in environmental policy, addressing persistent industrial pollution necessitates targeted interventions in emission controls, agricultural practices, and socioeconomic determinants to protect vulnerable populations within the global food system.