Cocktails of pesticide residues in Prochilodus lineatus fish of the Salado River (South America): First record of high concentrations of polar herbicides.

Muscle and viscera (gills-liver) of the fish Prochilodus lineatus were obtained from four sites of lower course of Salado river and one site at Santa Fe river near to its confluence with Salado river from Santa Fe (Argentina) between December 2021 and February 2022. Sediment samples were also obtained from the same sites. All samples were analyzed for pesticide residues following the QuEChERS method to quantify 136 compounds by UHPLC-ESI-MS/MS and GC-EI-MS/MS. Overall, muscle fish tissue showed very high concentrations (maximum concentrations detected) of the insecticide cypermethrin (204 μg/kg), polar herbicides (glyphosate; 187 μg/kg and its degradation product (aminomethylphosphonic acid) AMPA; 3116 μg/kg, and glufosinate-ammonium; 677 μg/kg), and the fungicide pyraclostrobin (50 μg/kg). In viscera samples, high values of cypermethrin (506 μg/kg), chlorpyrifos (78 μg/kg), and lambdacyhalothrin (73 μg/kg) were the main pesticides found. Mean residues concentrations detected among sites were not significantly different neither in muscle nor viscera of P. lineatus in most of the cases. Exceptionally, the southernmost studied site of the Lower Salado river showed significant differences in concentration of residues found in muscle, due to high concentrations of glyphosate and glufosinate-amonium (KW = 11.879 and KW = 13.013, respectively, P < 0.05). Other norther Lower Salado river site showed significant higher AMPA concentration in fish viscera than in the rest of the studied sites (KW = 12.86 P < 0.05). Some sediment samples showed low levels of herbicides such as glyphosate (24 μg/kg) and fungicides. However, the world highest levels of polar herbicides were recorded in fish muscle. The results of this study highlight the need for periodic monitoring due to the high concentration of pesticides and its potential risk in a very important commercial freshwater fish from Argentina, which is consumed locally and exported to other countries for human consumption.