Lifetime pharmacokinetic model for hydrophobic contaminants in marine mammals

A physiologically based pharmacokinetic model is developed that describes t he uptake and release of a hydrophobic organic chemical by a marine mammal over its entire lifetime, i.e., from birth to death. This model is applied to polychlorinated biphenyls (PCBs) in the beluga whale (Delphinapterus leu cas). The processes treated are growth; uptake from food. milk, and air; di sposition of the chemical among arterial and venous blood, liver, muscle, b lubber, and rapidly perfused tissues; and losses by metabolism, release in exhaled air, and by egestion. A separate model is developed for females, wh ich includes pregnancy, birth, and lactation. Food consumption is deduced f rom size, growth, and from activity-dependent bioenergetic data. The result s obtained by simulating continuous PCB exposure over a 30-year period are in accordance with reported concentrations and show the importance of milk transfer to both mother and progeny and the tendency for continued accumula tion over the animal's lifetime. Implications of the results are discussed. especially the need for improved data on diets, gut absorption characteris tics, and various physiological parameters used in the model.