Polychlorinated biphenyl elimination rates and changes in chemical activity in hibernating amphibians

The present study examined polychlorinated biphenyl (PCB) elimination rates in overwintering green frogs (Rana clamitans) to determine if changes in chemical activity occurred during hibernation. Adult green frogs were dosed with a 1:1:1 ratio of Aroclors 1248:1254:1260 in sunflower oil and allowed to enter into hibernation. Frogs were collected at four time points over the course of 85 days. Significant PCB elimination rates ranged from 0.0027 to 0.0376 d(-1). A negative correlation was found between K(OW) and elimination rate. Over the course of the present study, a decrease in total body percent lipid was measured. There was an overall increase in fugacity of higher K(OW) compounds corresponding to the relatively rapid decrease in lipid content. Congeners in metabolic group 2 (meta-para vicinal hydrogen atoms) were preferentially eliminated over those in metabolic group 3 (ortho-meta vicinal hydrogen atoms), suggesting that biotransformation was occurring during hibernation. It was concluded that metabolic activity during hibernation, associated with water temperature, was sufficiently high to reduce lipid concentrations and increase chemical activity in emerging adults.