Human health risk estimation of antibiotics transferred from wastewater and soil to crops

Antibiotics enter into agricultural land, via manure application or wastewater irrigation. The practices of using untreated wastewater in the agricultural system help in the bioaccumulation of antibiotics in vegetables and other crops. Exposure to the bioaccumulated antibiotics poses serious health risks to ecosystem and human. In this study, the prevalence of two fluoroquinolones (levofloxacin and ciprofloxacin), their bioaccumulation in five crops (Daucus carota L., Pisum sativum L., Raphanus raphanistrum L., Lactuca sativa L., Spinacia oleracea L.), and associated human health risks were investigated. Lettuce showed highest bioaccumulation of levofloxacin (LEV) (12.66 μg kg^-1) and carrot showed high bioaccumulation of ciprofloxacin (CIP) (13.01 μg kg^-1). In roots, bioconcentration factor (BCF_root) was observed to be relatively high in radish (LEV 0.24-0.43, CIP 0.32-0.49) and observed to be lower in spinach (LEV 0.05-0.13, CIP 0.12-0.19). The translocation factor (TF) for LEV and CIP was generally >1 for all five crops under all treatment. The final transfer and distribution of LEV and CIP in the edible parts of the crops were as follows: leaves > shoots > roots for both antibiotics. Risk quotient of both LEV and CIP in current study is found to be in between 0.018 and 0.557 and shows a medium risk (0.1 to 1) to human health due the discharge of untreated wastewater into the fields. However, our study reports that both antibiotics do accumulate in the edible plant parts; therefore, it poses potential risks to human health.