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Physiologically based pharmacokinetic (PBPK) models for wild animal populations such as marine mammals typically have a high degree of model uncertainty and variability due to the scarcity of information and the embryonic nature of this field. Parameters values used in marine mammals models are usually taken from other mammalian species (e.g. rats or mice) and might not be entirely suitable to properly explain the kinetics of pollutants in marine mammals. Therefore, several parameters for a PBPK model for the bioaccumulation and pharmacokinetics of PCB 153 in long-finned pilot whales were estimated in the present study using the Bayesian approach executed with Markov chain Monte Carlo (MCMC) simulations. This method uses prior information of the parameters, either from the literature or from previous model runs. The advantage is that this method uses such prior parameters to calculate probability distributions to determine posterior values that best explain the field observations. Those field observations or datasets were PCB 153 concentrations in blubber of long-finned pilot whales from Sandy Cape and Stanley, Tasmania, Australia. The model predictions showed an overall decrease in PCB 153 levels in blubber over the lifetime of the pilot whales. All parameters from the Sandy Cape model were updated using the Stanley dataset, except for the concentration of PCB 153 in the milk. The model presented here is a promising and preliminary start to PBPK modeling in long-finned pilot whales that would provide a basis for non-invasive studies in these protected marine mammals.

Pollution is a threat to the health of marine mammals worldwide. Mass-strandings are poorly understood, but often involve pilot whales. However, there is limited information regarding pollution in long-finned pilot whales from Australia. Consequently, the profiles and levels of several pollutant classes were investigated in blubber of Tasmanian long-finned pilot whales. DDX levels were highest in all groups, followed by PCBs or MeO-PBDEs and lowest for PBDEs. The concentrations of all pollutants decreased with age in males. This is at least partly due to the growth dilution effect although it might also be caused by decreasing levels of PCBs, PBDEs, DDXs, HCB and CHLs in the environment. Fetus/mother ratios of higher chlorinated PCBs increased with the duration of pregnancy suggesting a preference for offloading via gestation rather than through lactation. Overall, the highest pollutant levels were found in the youngest animals.