Evaluation of heavy metals in selected fruits in umuahia market, Nigeria: Associating toxicity to effect for improved metal risk assessment

Abstract

The cases of metabolic disorder and diseases have been linked to the toxicity of heavy metals in foods crops. This study evaluates the degree of heavy metals in selected fruits sold at Umuahia market in Nigeria. Ten different fruits were randomly selected. The fresh fruits comprised Solanum lycopersicum (Tomatoes), Cucumis sativus (Cucumber), Solanum melongena (Nigerian Egggarden), Citrullus lanatus (Watermelon), Dacryodes edulis (African bush pear), Juglans regia (Walnut), Syzgium malaccense (Mountain apple), Annona muricata (Soursop), Pachycarpa kschum (Monkey kola), and Dennettia tripetala (Pepper fruit), respectively. These fruits were slices to pieces and air dried; they were ground and digested. The heavy metals were screened with atomic absorption spectrophotometer. Their health risk assessment was analyzed based on established models. Results showed that zinc and lead were undetected in fruits such as C. sativus, S. melongena, C. lanatus, D. edulis, S. malaccense, S. melongena, J. regia, A. muricata, P. kschum, and D. tripetala. Nickel was undetected in S. melongena, J. regia, A. muricata, P. kschum, and D. tripetala and the absence of cobalt in C. lanatus and J. regia. The concentration of copper, chromium (Cr), and cadmium (Cd) was higher compared to their respective permissible limits in fruits. Iron concentration was 2.914 ± 0.002 ppm in P. kschum, with the fruits hazard index less than one (0.3434). Cr and Cd concentration falls within tolerance level in all the fruits with acceptable cancer risk-(<10−6). Total cancer risks of the fruits were >10−6, suggesting zero chance of developing cancer. This study suggests that most fruits are unsafe for human consumption and consumers should proffer a method of reducing the level of heavy metals in fruits.