Are fin whales (Balaenoptera physalus) exposed to microplastics toxicological threat?

The emerging issue of microplastics (plastic fragments smaller than 5 mm) in marine environment is recently raising increasing attention. The impacts of microplastics on baleen whales, which potentially undergo to the ingestion of micro-litter by filtrating feeding activity, are largely unknown. Here we present the case study of the Mediterranean fin whale (Balaenoptera physalus), exploring the toxicological effects of microplastics on mysticetes comparing two populations living in areas characterized by different human pressure: the Pelagos Sanctuary (Mediterranean Sea) and the Sea of Cortez (Mexico). The work is implemented through three steps: 1) collection/count of microplastics in Pelagos Sanctuary (Mediterranean Sea); 2) detection of phthalates in superficial neustonic/planktonic samples; 3) detection of phthalates and biomarkers responses (CYP1A1, CYP2B, lipid peroxidation) in skin biopsies of fin whales collected in the Pelagos Sanctuary (n=18) and Sea of Cortez (n=7). High presence of plastic particles have been detected in superficial neustonic/planktonic samples collected in the Pelagos Sanctuary areas investigated (mean value 0.62 items/m3 ) with high concentration of phthalates (DEHP and MEHP), used as tracers of plastic derivates. Relevant concentrations of MEHP and higher biomarker responses (CYP1A1, CYP2B, lipid peroxidation) were detected in the skin biopsies of fin whales collected in the Mediterranean areas in comparison to the specimens of Sea of Cortez. These results suggest the use of phthalates as a tracer of microplastics assumption in fin whales and represent a warning signal on this emerging threat in baleen whales.