Comparing metal bioaccumulation in crop types and consumable parts, between two growth periods

A high proportion of populations in most developing countries live below the poverty line, and those near refuse grounds resort to dumpsite farming to grow food. Consequently, high levels of waste-derived contaminants are found in crops consumed by these people. This study investigates the extent to which crops cultivated on the Mbale dumpsite (Uganda) were contaminated by 11 metals and 2 non-metals: iron (Fe), aluminium (Al), zinc (Zn), manganese (Mn), copper (Cu), mercury (Hg), lead (Pb), nickel (Ni), cobalt (Co), cadmium (Cd), selenium (Se), chromium (Cr), and arsenic (As). We investigated how element bioaccumulation in crops was influenced by the growth period (short-term and long-term crop maturity). The short-term crops were Zea mays and Amaranthus cruentus whereas the long-term crops were Manihot esculenta, Colocasia esculenta, Musa acuminata, Carica papaya, Coffea arabica and Saccharum officinarum.

Results showed that nine metals were present at concentrations above WHO/FAO food safety recommendations and hence may pose health risks to consumers. In this study, leaves contained higher metal concentrations than other analysed consumable parts. Pb and Co were found at higher concentrations in leaves of short-term, than in long-term crops. Among short-term crops, only Zea mays grains/seeds contained permissible metal concentrations by WHO/FAO standards.

The growth period was also found to influence metal bioaccumulation in crop types. Pb, Co, Fe, Al, and Cu concentrations were significantly higher in the short-term than in long-term crops while Mn, Ni and Cr concentrations were higher in long-term than in short-term crops. Overall, public awareness about health risks associated with consuming short-term leafy crops grown on dumpsites should be escalated to reduce toxic metal exposure. While implementing such a campaign, the food supply of individuals whose survival depends on https://biodas.org/ such crops should not be jeopardized. Therefore, farmers need alternative farming areas outside dumpsites.