Risk assessment of metals and α-toxin producing Gram-negative bacteria in leafy vegetables from Akinyele, Oyo State, Nigeria

Consumption of vegetables confers nutritional health benefits, but are susceptible to metal pollution and microbial contamination, posing significant public health risk. The study aimed to determine the extent of microbial load, metals and risk assessments of some commonly consumed leafy vegetables sold within Akinyele region of Oyo State, Nigeria. The levels of metals (lead Pb , Chromium Cr , Cadmium Cd and Copper Cu ) in the vegetables were determined using Buck Scientific Atomic Absorption Spectrophotometer. Microbial load was estimated using the pour plate method and screening for lecithinase (α-toxin), on egg yolk medium. Average concentrations of Pb, Cd and Cu were in the range of 0.00-17.36 mg.kg ^− 1 , 0.00-1.15 mg.kg ^− 1 and 12.53–77.11 mg.kg ^− 1 , respectively. Chromium was undetected in most of the vegetables. Levels of Cr and Cu were within the safety baseline levels while Pb and Cd levels exceeded the permissible limits for human consumption. Average hazard index (HI) in children was higher than in adults. Average HI of children and adults was > 1, so risk on human health cannot be ignored. Pumpkin and waterleaf contributed mostly to health risks, especially for children. Estimated microbial load from the vegetables did not exceed the threshold of > 7 log ₁₀ CFU/g, but was within the range of 4.67 to 5.34 log ₁₀ CFU/g. Lecithinase production was positive in 32% of the isolates. Toxigenic microbes and metals were present in the sampled vegetables at levels posing carcinogenic and non-carcinogenic risks. Therefore, regular monitoring of vended vegetables is recommended for public safety.