Accumulation of potentially harmful elements (PHEs) in lettuce (Lactuca sativa L.) and coriander (Coriandrum sativum L.) irrigated with wastewater: a systematic review and meta-analysis and probabilistic health risk assessment

Water shortage and stress around the world lead to increasing wastewater reuse for the agricultural sector. In addition to its benefits, it can be a way to transfer pollutants such as potentially harmful elements (PHEs) to the human food chain. Many studies have been conducted for this purpose on various vegetables; however, no comprehensive study has been performed on lettuce (Lactuca sativa L.) and coriander (Coriandrum sativum L.). In this respect, the study was aimed to meta-analyze the PHEs concentration in the edible part of lettuce and coriander vegetables irrigated by wastewater. Carcinogenic risk (CR) and noncarcinogenic risk (non-CR) assessments were also done for consumers. After reviewing 32 included articles (41 studies), the rank order of the PHEs in lettuce was obtained as Fe (194.76 mg/kg) > Zn (133.47 mg/kg) > Cu (55.70 mg/kg) > Ni (26.96 mg/kg) > Pb (12.80 mg/kg) > Cr (9.68 mg/kg) Cd (8.24 mg/kg) > As (1.13 mg/kg) and for coriander Fe (1056 mg/kg) > Zn (79.80 mg/kg) > Cr (28.34 mg/kg) > Ni (24.71 mg/kg) > Cu (17.46 mg/kg) > Pb (13.23 mg/kg) > Cd (2.23 mg/kg). Total target hazard quotient (TTHQ) for adults in all countries except UAE, France, and Kenya and for children all countries except Kenya was more than 1 value. The carcinogenic risk for adult groups in Nigeria, France, China, and Iran countries was not acceptable (CR > 1E-4). As a consequence, it can be noted that wastewater reuse in the agriculture sector can endanger the health of consumers.