Occurrence and human health risks of pesticides and antibiotics in Nile tilapia along the Rosetta Nile branch, Egypt

Abstract

Nile tilapia (Oreochromis niloticus) samples were collected at monthly intervals between July 2018 and June 2019 from 3 sampling sites (El-Rahawy, Sabal and Tala) situated along the Rosetta branch of the Nile, Egypt, to monitor the presence of 100 pesticides and 5 antibiotics using different extraction procedures followed by GC-MS/MS and LC-MS/MS. Potential human health risks via the consumption of contaminated fish was also assessed. Of the 72 analyzed fish muscle samples; 86% and 21% were contaminated with pesticides and antibiotics, respectively. Chlorpyrifos (ranging from < LOQ to 0.08 mg/kg) was the most frequently detected pesticide followed by p,p'-DDE (ranging from < LOQ to 0.04 mg/kg) in 83 and 45% of the fish muscle samples, respectively. Nitrofurazone (ranging from 8.6 to 52 μg/kg) was the most frequently detected antibiotic, followed by nitrofurantoin (ranging from 1.1 to 2 μg/kg) and chloramphenicol (ranging from < LOQ to 0.17 μg/kg). These antibiotics were found in 12, 6 and 5% of the fish muscle samples, respectively. The spatial distribution of the detected pesticides and antibiotics in fish samples along the Rosetta branch showed that the highest mean concentrations were found in the Sabal area, followed by samples from Tala and El-Rahawy. An investigation into seasonal variations revealed that the highest mean concentrations of pesticides and antibiotics in fish samples were detected in winter and spring, respectively. According to target hazard quotient (THQ) calculations for the detected pollutants in Nile tilapia muscle, all pollutants gave THQ values lower than 1, indicating that the consumption of this fish from the study sites is unlikely to cause any detrimental effects to consumers.

Keywords: Contaminants; Nile tilapia; Risk assessment; Spatiotemporal variations.

Fig. 1

The sampling sites of Nile tilapia along the Rosetta branch, river Nile, Egypt.