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Ammonium perfluorooctanoate (APFO) is a processing aid in the production of fluoropolymers that has been shown to have a long half-life in human blood. To understand the potential toxicological response of primates, groups of male cynomolgus monkeys were given daily po (capsule) doses of either 0, 3, 10, or 30 (reduced to 20) mg/kg/day for 26 weeks. Two monkeys from each of the control and 10 mg/kg/day dose groups were observed for 90 days after the last dose. Clinical observations, clinical chemistry, determination of key hormones, gross and microscopic pathology, cell proliferation, peroxisomal proliferation, bile-acid determination, and serum and liver perfluorooctanoate (PFOA) concentrations were monitored. Toxicity, including weight loss and reduced food consumption, was noted early in the study at the 30 mg/kg/day dose; therefore, the dose was reduced to 20 mg/kg/day. The same signs of toxicity developed in 3 monkeys at 20 mg/kg/day, after which treatment of these monkeys was discontinued. One 30/20 mg/kg/day monkey developed the signs of toxicity noted above and a possible dosing injury, and this monkey was sacrificed in extremis on Day 29. A 3 mg/kg/day dose-group monkey was sacrificed in extremis on Day 137 for reasons not clearly related to APFO treatment. Dose-dependent increases in liver weight as a result of mitochondrial proliferation occurred in all APFO-treated groups. Histopathologic evidence of liver injury was not observed at either 3 or 10 mg/kg/day. Evidence of liver damage was seen in the monkey sacrificed in moribund condition at the highest dose. Body weights were decreased at 30/20 mg/kg. PFOA concentrations in serum and liver were highly variable, were not linearly proportional to dose, and cleared to background levels within 90 days after the last dose. A no observable effect level was not established in this study, and the low dose of 3 mg/kg/day was considered the lowest observable effect level based on increased liver weight and uncertainty as to the etiology leading to the moribund sacrifice of one low-dose monkey on Day 137. Other than those noted above, there were no APFO-related macroscopic or microscopic changes, changes in clinical chemistry, hormones, or urinalysis, or hematological effects. In particular, effects that have been associated with the development of pancreatic and testicular toxicity in rats were not observed in this study.

Perfluorobutyrate (PFBA) has been detected in precipitation, surface waters, water treatment effluent, and in public and private wells in Minnesota at up to low microg/l concentrations. We evaluated the pharmacokinetics of PFBA in rats, mice, monkeys, and humans to provide a rational basis for dose selection in toxicological studies and to aid in human-health-risk assessment. Studies included (1) rats--iv and oral; (2) mice--oral; (3) monkeys--iv; and (4) humans--occupationally exposed volunteers. PFBA was determined in serum (all species), liver (rats and mice), urine (rats, mice, and monkeys), and feces (rats and mice). In addition, we characterized serum PFBA concentrations in 177 individuals with potential exposure to PFBA through drinking water. Mean terminal serum PFBA elimination half-lives for males (M) and females (F), respectively, in h were (1) for rats given 30 mg/kg, 9.22 and 1.76 (oral), and 6.38 and 1.03 (iv); (2) for mice given oral doses of 10, 30, or 100 mg/kg ammonium PFBA, 13.34 and 2.87 at 10 mg/kg, 16.25 and 3.08 at 30 mg/kg; and 5.22 and 2.79 at 100 mg/kg; (3) for monkeys given 10 mg/kg iv, 40.32 and 41.04; and (4) for humans, 72.16 and 87.00 (74.63 combined). Volume of distribution estimates indicated primarily extracellular distribution. Among individuals with plausible exposure via drinking water, 96% of serum PFBA concentrations were < 2 ng/ml (maximum 6 ng/ml). These findings demonstrate that PFBA is eliminated efficiently from serum with a low potential for accumulation from repeated exposure.

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