Kinetics of Excretion of the Perfluoroalkyl Surfactant cC6O4 in Humans

cC6O4 is a new-generation perfluoroalkyl surfactant used in the chemical industry for the synthesis of perfluoroalkyl polymers. It was introduced as a less biopersistent substitute of traditional perfluoroalkyl surfactants such as PFOA, but its kinetics in humans was never investigated. This work is aimed to investigate the kinetics of elimination of cC6O4 in exposed workers. Eighteen male individuals occupationally exposed to cC6O4 in the production of fluoropolymers volunteered for the study. Blood and urine samples were collected from the end of a work-shift for the following 5 days off work. Serum and urinary cC6O4 were measured by LC-MS/MS. Seventy-two samples with serum cC6O4 ranging from 0.38 to 11.29 μg/L were obtained; mean levels were 3.07, 2.82, 2.67 and 2.01 μg/L at times 0, 18, 42 and 114 h. Two hundred and fifty-four urine samples with cC6O4 ranging from 0.19 to 5.92 μg/L were obtained. A random-intercept multiple regression model was applied to serum data and a half-life of 184 (95% CI 162–213) h for a first-order kinetics elimination was calculated; a mean distribution volume of 80 mL/kg was also estimated. Pearson’s correlation between ln-transformed serum and daily urine concentrations was good, with r ranging from 0.802 to 0.838. The amount of cC6O4 excreted daily in urine was about 20% of the amount present in serum. The study allowed calculating a half-life for cC6O4 in blood of about 8 days in humans, supporting its much shorter biopersistence in comparison with legacy PFAS. The good correlation between urine and serum cC6O4 suggests urine as a possible non-invasive matrix for biomonitoring. The amount of cC6O4 excreted daily in urine suggests urine as the sole elimination route.