A Mechanistic Investigation of Perfluoroalkyl Acid Kinetics in Rainbow Trout (Oncorhynchus mykiss)

Abstract

Rainbow trout (Oncorhynchus mykiss) confined to respirometer-metabolism chambers were dosed with perfluorooctane sulfonate (PFOS) or perfluorooctanoate (PFOA) by intra-arterial injection and sampled to obtain concentration time-course data for plasma, urine and/or expired water. The data were then analyzed using 2-compartment clearance-volume models. Renal and branchial clearance rates determined for all PFOS experiments averaged 19% and 81% of total clearance, respectively. In contrast, PFOA renal and branchial clearance averaged 92% and 8% respectively. The terminal half-life was 86.8 d for PFOS and 12.6 d for PFOA. Tissue distributions for both compounds were consistent with previous studies. Additional animals were exposed to PFOS and PFOA in water, resulting in average calculated branchial uptake efficiencies of 0.36% and 0.1% respectively. The renal clearance rate determined for PFOS was approximately 75 times lower than that determined for PFOA. This study suggests that glomerular filtration may be sufficient to explain the observed renal clearance rate for PFOS, although a role for membrane transporters cannot be ruled out. However, the results for PFOA suggest that PFOA is a substrate for membrane transporters in the trout kidney. These findings demonstrate that models developed to predict the bioaccumulation of perfluoroalkyl acids by fish must account for differences in renal clearance of individual compounds.