Assessment of Aflatoxin and Heavy Metal Contamination in Milled Melon Seeds from Selected Lagos State Markets: Implications for Food Safety

Abstract

Milled melon seeds (Citrullus colocynthis) are often consumed as part of soup ingredients in Nigeria; however, they are susceptible to aflatoxin and heavy metal contamination. In this study, milled melon samples from three Lagos State markets (Badagry, Epe, and Mile 12) and a laboratory-prepared control were evaluated for aflatoxins and heavy metals. Thereafter, the contaminants were compared to international safety standards. The results showed that the total aflatoxin concentrations ranged from 0.09 to 0.36 μg/kg, with mean concentrations of aflatoxin B1 (0.06 μg/kg), aflatoxin B2 (below detection), aflatoxin G1 (0.03 μg/kg), and aflatoxin G2 (0.12 μg/kg). The aflatoxin levels were well below the recommended maximum level of 4 μg/kg by the National Agency for Food and Drug Administration and Control, and 20 μg/kg set by the United States Food and Drug Administration (FDA). On the other hand, the heavy metals varied significantly (p<0.05) and were higher than global limits. The values obtained for lead (Pb) ranged from 0.46 mg/kg (control) to 1.91 mg/kg (Epe samples). Generally, the values obtained for Pb frequently exceeded EU and Codex guidelines (0.10–0.30 mg/kg); the Epe sample had 0.80 mg/kg chromium (Cr) and was above the WHO limit of 0.20 mg/kg. The most abundant element was copper (Cu), which was higher in the Epe sample at 4.54 mg/kg, while being within FDA and FAO/WHO standards. The arsenic (As) constituent was below detection; cadmium (Cd) was found at trace quantities (≤0.10 mg/kg). Aflatoxin pollution was generally minimal, but exposure to heavy metals, especially Pb and Cr, poses serious dangers to human health. The results highlight the necessity for a more stringent enforcement of food safety laws, better post-harvest handling, and regular monitoring to protect consumers.