Ultrasonic Extraction-Based Analysis of Persistent Organic Pollutants in Blubber from False Killer Whales

In view of the toxic effects of persistent organic pollutants (POPs), fast and effective assessment of their concentrations in marine mammals is important for understanding individual and population-level health impacts. This study developed an ultrasonic-based method that is less time-consuming, uses minimal solvent, and thus is more sustainable than the gold standard Soxhlet method for accurate analysis of organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), and benzene hexachlorides (BHC) in false killer whale blubber. This method was developed by comparing concentrations of POPs obtained using the traditional Soxhlet and novel ultrasonic extraction methods using blubber from false killer whales (n = 4) that were stranded in the Hawaiian Islands. The average total POPs extracted from the four killer whales and adjusted for lipid weight (lw) were 11,379.57 ± 3,303.03 ng/g lw for Soxhlet extraction and 14,310.39 ± 4,469.00 ng/g lw for the ultrasonic method, indicating a greater extraction efficiency of the ultrasonic method. The results further revealed that false killer whale FKW2013018 (∑OCs 15,447.38 ± 812.17 ng/g lw and ∑PCBs 5,205.32 ± 253.46 ng/g lw) and false killer whale FKW2016016 (∑OCs 18,164.90 ± 1,433.15 ng/g lw and ∑PCBs 4,913.32 ± 447.29 ng/g lw) accumulated organochlorines and PCBs at very high and potentially toxic levels. The low ratio of 4,4'-DDT/4,4'-DDE (0.026 ± 0.004) using both extraction methods indicated that the stranded false killer whales experienced long-term exposure to 4,4'-DDT, leading to bioaccumulation of the stable 4,4'-DDE metabolite. The levels of OCs, PCBs, and BHCs in this study were below toxic threshold levels. However, in view of the susceptibility of cetaceans with reduced lipid content to the toxic effects of POPs, cetaceans with low lipid content (as a result of starvation, fasting, or extended migration events) may be at higher risk of the negative health impacts of organic pollutants.