Occurrence of Trace Metals in Food Crops Grown on the Mbale Dumpsite, Uganda, and Human Health Risks

Abstract Food crops can be used as biomonitors to assess potential public health food safety hazards from contaminated agricultural environments. Globally, more than 800 million people grow fruits, vegetables, and grains on urban garden soils with unknown health risks. This worldwide practice has exposed consumers to pathogenic and carcinogenic risks from locally grown and imported contaminated foodstuffs such as Amaranthus cruentus and Zea mays, traditional and widely consumed crops across the globe. This study used Z. mays and A. cruentus crops to investigate the occurrence and spatial variations of aluminum (Al), chromium (Cr), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), mercury (Hg), and lead (Pb) concentrations across the Mbale dumpsite, Uganda. Mean concentrations for Fe, Al, Zn, Mn, and Cu were high in both crops, whereas Pb, Cr, Co, Cd, As, Hg, Se, and Ni occurred in trace amounts. Using the 2 crops as biomonitors, significant variations for Al, Zn, Fe, Cr, and Co concentrations in individual crops were identified across the dump center, hill slope, and riverbank. The variations in Al, Zn, Fe, Cr, and Co concentrations were specific for crop types, crop parts, and location. The highest overall accumulation of metals was at the dump center and in crop leaves. Except Pb concentrations in Z. mays seeds, Cr, Pb, Zn, and Al concentrations in other crop parts were above World Health Organization/Food and Agricultural Organization consumer food safety limits. Therefore, Z. mays and A. cruentus consumption could pose health risks to consumers. Further health assessments and potential regulations are recommended to reduce potential health risks from metals in crops for human consumption. Integr Environ Assess Manag 2020;16:362–377. © 2019 SETAC KEY POINTS Spatial metal distribution across the Mbale dumpsite zones were assessed using Amaranthus cruentus and Zea mays crops. Al, Zn, Fe, Cr, and Co concentrations in individual crops significantly varied across the three zones. Pb, Cr, Al, and Zn in most crop parts were above the recommended WHO/FAO food safety limits. The highest metal accumulation was at the dump center and in crop leaves.