Microbial exposure risk assessment of urban wastewater by irrigation of agricultural products

Background: This study was designed to investigate microbial exposure risk assessment and consequences of adverse health effects due to the use of irrigation of fields with wastewater in Qom province Methods: Environmental monitoring program for 3 pathogens including Escherichia coli, Vibrio cholerae and Ecoli O157 in raw sewage and treated wastewater and irrigated products with wastewater, was performed. Results: Results was shown that in the raw wastewater, concentrations of E.coli, Vibrio Cholerae and E.coli O157:H7, 3.4×103±500, 2.1×103±100 and 312 respectively were determined. Concentrations of E.coli, Vibrio Cholerae and E.coli O157:H7 in wastewater effluent 2.1×103±100, 0.8×103±100 and 176 respectively were determined. Based on these findings, it is determined that the conventional wastewater treatment system has been effective in removing E.coli, Vibrio Cholerae and E.coli O157: H7 by 50%, 59% and 43%, respectively. Irrigated crops with wastewater effluent containing 400±250, 0.1×103±0.019 and 52 for E.coli, Vibrio Cholerae and E.coli O157:H7 respectively were measured. In this study according to the exposure scenarios including accidental drinking, food crop consumption, dermal contact by wastewater effluent and dermal contact by raw wastewater, total annual Probability of infection in studied population for E.coli, Vibrio Cholerae and E.coli O157:H7, 8×10-2, 8×10-4 and 0.17 respectively was determined. Conclusions: Implementing of wastewater safety plans (WWSP) to safeguard wastewater quality, raising awareness in the population in contact with urban wastewater and upgrading wastewater treatment plants is inevitable.