Development and application of a blubber-based detection protocol for phthalate ester metabolites in bottlenose dolphins (Tursiops truncatus).

Phthalates (PAEs) are high production volume plasticizing chemicals linked to endocrine disruption in mammals. Phthalates are released from the products to which they are added, leading to environmental exposure for humans and wildlife. Recent studies of bottlenose dolphin (Tursiops truncatus) urine have demonstrated prevalent exposure to phthalates. This study developed a protocol for phthalate ester metabolite (mPAE) detection in bottlenose dolphin blubber (~ 200 mg), a matrix that can be sampled remotely, and has been used to assess contaminant exposure (e.g., persistent organic pollutants and trace metals) in cetaceans in the past. Sonication in ammonium acetate, solid-phase extraction, and high-performance liquid chromatography-tandem mass spectrometry were used to extract and quantify mPAEs in blubber, and the finalized method was applied to samples (n = 27) collected during dolphin health assessments conducted in Sarasota Bay, FL, USA in 2016, 2017, 2022, and 2023. Detectable concentrations of three mPAEs (mono-2-ethylhexyl phthalate (MEHP; n = 6; censored mean: 3.0 ng/g wet weight; 5.2-12.4 ng/g ww), monoethyl phthalate (MEP; n = 2; ng/g ww; 39.7-50.1 ng/g ww), monoisodecyl phthalate (MIDP; n = 3; 26.0-27.4 ng/g ww)) were observed across the dataset, with at least one mPAE detected in 37% of sampled dolphins. Blubber provides a remote sampling option to investigate PAE exposure, particularly high-molecular-weight compounds, in populations where health assessments are not feasible. Blubber samples of the size analyzed in this study can be obtained via remote biopsy dart sampling, a method used globally to monitor contaminants in marine mammals. This approach facilitates exposure assessments in at-risk or remote populations, increases the efficiency of field sampling efforts, and reduces stress for animals.