Health Effects of Heavy Metals in Edible Tubers (Cassava, Sweet Potato, and Yam): A Review of Implications for Food Safety and Public Health

Abstract Cassava (Manihot esculenta), sweet potato (Ipomoea batatas), and yam (Dioscorea spp.) are critical staple foods for millions of people, particularly in sub-Saharan Africa, Asia, and Latin America. Their cultivation in marginal and often contaminated soils increases the risk of heavy metal accumulation in edible tissues. Heavy metals such as cadmium (Cd), lead (Pb), mercury (Hg), arsenic (As), chromium (Cr), nickel (Ni), copper (Cu), and zinc (Zn) are persistent environmental contaminants that can enter the human food chain through tuber crops and pose significant health risks upon chronic exposure. This review critically evaluates current evidence on the sources, uptake mechanisms, and concentration levels of heavy metals in cassava, sweet potato, and yam, as well as their associated health effects. Reported concentrations are compared with international food safety limits, and human health risk assessment outcomes are synthesized. The review highlights substantial exceedances of FAO/WHO guideline values in contaminated regions and underscores the need for strengthened monitoring, soil management, and policy interventions to safeguard public health.