Bioaccumulation of heavy metals in frequently consumed leafy vegetable grown along Nigeria-Benin Seme Border, West Africa.
Vegetable growing along major highways with heavy vehicular movement has been a serious concern to food safety specialist in large cities. The contributions of heavy metals in selected vegetables through atmospheric deposition were quantified using atomic absorption spectrophotometer. The level of some heavy metal (Pb, Cu, Fe, and Cr) were examined in the edible portion of Telfciria occidentals, Corchorus olitorius, Celocia argentea, and Thymus Vulgaries, grown along Nigeria-Republic of Benin border Seme. The results showed that the levels of heavy metal ranged from 21.69±7.36 µg/g Cu to 172.87±62.05 µg/g Fe in Telfaria occidentalis, 21.74±13.00 µg/g Pb to 304.50±72.77 µg/g Fe in Corchorus olitorius, 16.75±10.54 µg/g Pb to 260.74±215.37 µg/g Fe in Celocia argentea and 23.53±3.52 µg/g Cu to 406.33±225.06 µg/g Fe in Thymus Vulgaries were recorded in site A. The value heavy metal contamination obtained from site B ranged from 18.91±11.98 µg/g Pb to 166.49±86.22 µg/g Fe in Telfaria occidentalis, 16.57±9.22 µg/g Pb to 292.36±196.33 µg/g Fe in Corchorus olitorius, 19.99±8.54 µg/g Pb to 354.03±302.80 Fe in Celocia argentea and 21.73±8.44 µg/g Pb to 388.20±226.39 µg/g Fe in Thymus Vulgaries. The order of contamination in the vegetable sample was Fe > Cr > Cu > Pb. The data were analyzed with t-test and ANOVA. There were no significant different between the (p<.05) between the level of heavy metal in vegetable at each sampling site. The high levels of metal in the sampled vegetable may be attributed to excessive application of fertilizers and other agro chemical, as well the use of use of waste water for washing the vegetables. The obtained results were higher than the threshold value of WHO, FEPA and China stipulated standards for mature plant tissue except for copper in all the analyzed vegetable. Therefore, the consumption of these vegetables as food may pose possible health hazards to human.