Pyrethroid bioaccumulation in Mediterranen dolphins

Pyrethroids are organic pollutants with high hydrophobicity used as insecticides. Concern exists about aquatic organisms¿ exposure to their toxicity. They were believed to be converted to non-toxic metabolites in mammals, but our group has detected them in human breast milk and has proved their bioaccumulation in marine mammals and river fish. The present study investigates the occurrence of pyrethroid compounds in liver samples from striped dolphins (Stenella coeruleoalba)and common dolphins (Delphinus delphis) from southern Spain, as the first attempt to determine the occurrence and bioaccumulation and distribution of pyrethroids in marine mammal tissues from the Mediterranean Sea. Samples of dolphin tissue were collected from the Abloran Sea (south of Spain) between 2003 and 2010, including 37 liver samples from striped dolphin and different tissues¿blubber, muscle, liver, brain and kidneys¿from 11 common dolphins. The analytical method monitored 10 pyrethroids, including cypermethrin and detamethrin. For the sample preparation?lyophilized sample was spiked with internal standards, extracted by sonication and underwent a clean-up with alumina and C18 SPE cartridges. Extracts were analysed by GC-NCI-MS/MS. Method recoveries for the pyrethroids ranged 53-116?% and method LODs and LOQs were 0.02-0.46?ng/g and 0.08-1.54?ng/g, respectively. Pyrethroids were detected in 87?% of the striped dolphins and 100?% of the common dolphins, with total concentrations of nd-5,210?ng/g?lw and 69-2,036?ng/g?lw, respectively. These levels were higher than those reported found in dolphins from Brazil (7.0-68?ng/g?lw). Permethrin and tetramethrin were the main contributors to the pyrethroid profiles for all tissues. The samples of striped dolphins where used to observe that bioaccumulation of pyrethroids was unlike that of persistent organic pollutants (POPs), as pyrethroid levels were not correlated to the age of the specimens. Levels slightly increase from calves to juveniles, whereas juveniles present similar levels to adults. Metabolization of pyrethroids after achieving sexual maturity might account for this pattern. Because of the pyrethroids lipophilic behaviour, blubber was the most contaminated tissue and brain showed the lowest levels. Normalizing the data to the lipid content, the highest value was for muscle by far, suggesting a preference for that tissue. SETA