Accumulation and elimination kinetics of dietary endosulfan in Atlantic salmon (Salmo salar)

Abstract The carry-over of dietary endosulfan to the fillet of farmed Atlantic salmon was studied. The uptake and elimination rate constants of the α and β isoform of endosulfan were determined in seawater adapted Atlantic salmon (initial weigh 173 ± 25 g) fed on endosulfan enriched diets (724 and 315 μg kg −1 for α- and β-endosulfan, respectively) for 92 days, followed by a 56 days depuration period with feeding on control diets ( −1 endosulfan). The accumulation of the toxic metabolite endosulfan sulphate, which was not detected ( −1 ) in the experimental feeds, was also determined. Dietary β-endosulfan was more persistent than α-endosulfan as demonstrated by a higher uptake (41 ± 8% vs. 21 ± 2%) and lower elimination (26 ± 2 × 10 −3  day −1 vs. 40 ± 1 × 10 −3  day −1 ) rate constants, and a higher biomagnification factor (0.10 ± 0.026 vs. 0.05 ± 0.003, p −1 would cause the estimated maximum residue level (MRL) in fillet of 0.47 mg kg −1 to be exceeded. Model estimations also predict that current EU maximum permitted levels in fish feeds (0.005 mg kg −1 ) would give fillet concentrations that are under the detection limit (0.3 μg kg −1 ), which is in agreement with the general absence of endosulfan in monitored farmed Atlantic salmon.