Heavy Metals Concentration in Greens Sold in Umuahia-market Nigeria: Assessment of Risk to Human Health

Background: The consumption of foods with a high concentration of heavy metals has increased the chances of incurring cancer and health disorders. In this study, the risks associated with ingestion and consumption of heavy metals in vegetables was evaluated. Methods: Ten different vegetables were purchased from the Ubani market, in Umuahia – Nigeria. The vegetables - Gnetum africanum, Vernonia amygdalina, Talinum triangulare, Solanum macrocarpon, Ocimum gratissimum, Gongronema latifolium, Pterocarpus mildbraedi, Telfairia occidentalis, Amaranthus hybridus, and Piper guineense, respectively were randomly selected and used to screen for heavy metals. The vegetable samples were air dried, ground and digested with acid, separately using standard methods. The heavy metal contents of the acid digests were analyzed using Atomic absorption spectrophotometer. Results: The risk assessment of human health was interpolated with standard models. Results of the heavy metal showed that the vegetables have a high level of heavy metals. Some of the heavy metals detected in the vegetables exceeded their respective safety levels. The concentrations of zinc, nickel, and cobalt were not detected in most vegetables. Copper, chromium, and cadmium were above the permissible limits. Iron concentration was (12.092±0.100ppm) in a. hybridus which was the highest. The daily intake of heavy metals in vegetables was below tolerable prescription. The hazard index of the vegetable - G. latifolium was greater than 1, which implied adverse health effect. The hazard index - A. africanum and T. triangulare were equal to 1 suggesting that adverse health effect may occur. P. schum had a high concentration of chromium which makes it unsafe for consumption due to the risk of cancer. Lead showed no cancer risk, while nickel, chromium, and cadmium in vegetables were within the acceptable risk (<10-6). The total cancer risks of all vegetables were less than (<10-6) suggesting no/low chance of developing cancer. Conclusion: Therefore prolong consumption of these vegetables may put the consumers at risk. This study reason that some vegetables used for this investigation are unsafe for human consumption. And strongly suggest that consumers should be informed about the possible health effects of prolonged consumption/ingestion of heavy metals in order to prevent the possibility of metal toxicity