Insecticide pyrethroids in liver of striped dolphin from the Mediterranean Sea

•First study of pyrethroids in marine mammal tissue from the northern hemisphere.•Pyrethroids found in 87% of samples: mean 300 ng/g lw ± 932 (2.68-5210 ng/g lw).•Stripped dolphins showed some isomeric and enantiomeric specific accumulation.•Pyrethroid concentrations were not correlated to maturity stage of the dolphins.

Pyrethroid pesticides were analysed in liver of striped dolphin (Stenella coeruleoalba) from the Alboran Sea (south of Spain, Mediterranean Sea). The occurrence and bioaccumulation of pyrethroid insecticides in marine mammal tissues from the northern hemisphere had never been determined before. Pyrethroids were detected in 87% of the specimens with a mean total concentration of 300 ng g-1 lw ± 932 (range 2.7-5200 ng g-1 lw). Permethrin and tetramethrin were the main contributors to the pyrethroid profiles, with enantiospecific accumulation for the first and isomer specific accumulation for the latter. Bioaccumulation of pyrethroids was unlike that of persistent organic pollutants (POPs), as pyrethroid concentrations were not correlated to the maturity stage of the specimens. Concentrations slightly increased from calves to juveniles, whereas juveniles presented similar concentrations to adults. Metabolization of pyrethroids after achieving sexual maturity might account for this pattern.

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