Comprehensive analysis of heavy metals content in organic and conventional vegetables and their health risk assessment

In this study, we assessed the heavy metal content lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) in five different types of vegetables from the Kenitra region of Morocco using atomic absorption spectrometry (AAS). Both conventional and organic vegetables, including tomatoes, carrots, green peppers, corianders, and mints were examined. In order to assess the reliability of the analytical method, standard reference materials (SRM 1547 Peach Leaves and SRM 1573a Tomato Leaves) from the National Institute of Standards and Technology (NIST) have been analyzed. The results obtained showed good agreement with the certified values. Analysis of vegetable samples revealed that the average concentrations of the four heavy metals were generally higher in products from conventional agriculture compared to those from organic agriculture. The mean concentrations of Pb, Cd, As, and Hg in the five vegetables were 0.0116, 0.1215, 0.5760 and 0.0099 mg kg-1 for organic vegetables, slightly lower than those found in conventional vegetables which had concentrations of 0.0167, 0.1599, 0.7301 and 0.0198 mg kg-1. These results clearly demonstrate that the cultivation method significantly influences the bioaccumulation of heavy metals in vegetables. Health risk indexes associated with vegetable consumption have been calculated based on the estimated dietary intake (EDI), the target hazard quotient (THQ), the hazard index (HI) and the target cancer risk (TCR). The (EDI) values for both organic and conventional vegetables were below the reference dose. The (THQ) values for all heavy metals were less than 1 in both types of vegetables. The (TCR) values for each heavy metal in each vegetable sample were lower than 1 x 10-6, and the cumulative exposure to all heavy metals was lower than 1 x 10-5 for each vegetable. According to these results, there is no significant health risk associated with the consumption of these crops.