Health Risk Assessment of Trace Metal Elements in Treated Wastewater Reused in Agriculture in Tunisia

Our study first aimed to establish preliminary outcomes on the indirect interrelation between the safe use of treated wastewater, agricultural production and consumer health as well as provide real and better view of the risk in relation with wastewater reuse. To do so, a specific survey for analytical purposes was carried out in 2015 including three critical stages. The first aimed the determination of trace metals in irrigation water, agricultural products and soil, both in irrigated areas with freshwater (control plots) and those with treated wastewater. The second stage concerned the interpretation of the survey conducted among farmers and inhabitants working or living in/near the irrigated districts selected under this study (Borj Touil, Ouardanine, Oued Souhil, El-Aguila and Hamma, located in the governorates of Ariana, Monastir, Nabeul, Gafsa and Gabes, respectively), at rate of 50 questionnaires per governorate. The third component was the evaluation of health risks related to the consumption of agricultural products from two study perimeters, a control perimeter and a perimeter irrigated with treated wastewater. Preliminary results focused on the occurrence of trace metals in treated wastewater indicate that water quality was in compliance with the Tunisian standards for reuse (NT.106.03). However, we have noticed that the lead content in some agricultural products intended for human consumption (milk from the Borj Touil area or citrus from Oued Souhil) had exceeded the limit values (0.02 mg/kg) admitted by the Codex standard or the Tunisian joint decree of May 13, 2013.