Evaluation of the Chronic Toxicity and Carcinogenicity of Perfluorohexanoic Acid (PFHxA) in Sprague-Dawley Rats

Abstract

Perfluorohexanoic acid (PFHxA), a 6-carbon perfluoroalkyl (C6; CAS # 307-24-4), has been proposed as a replacement for the commonly used 8-carbon perfluoroalkyls: perfluorooctanoic acid and perfluorooctane sulfonate. PFHxA is not currently a commercial product but rather the ultimate degradation product of C6 fluorotelomer used to make C6 fluorotelomer acrylate polymers. It can be expected that, to a greater or lesser extent, the environmental loading of PFHxA will increase, as C6 fluorotelomer acrylate treatments are used and waste is generated. This article reports on a chronic study (duration 104 weeks) that was performed to evaluate the possible toxicologic and carcinogenic effects of PFHxA in gavage (daily gavage, 7 days per week) treated male and female Sprague-Dawley (SD) rats. In the current study, dosage levels of 0, 2.5, 15, and 100 mg/kg/day of PFHxA (males) and 5, 30, and 200 mg/kg/day of PFHxA (females) were selected based on a previous subchronic investigation. No effects on body weights, food consumption, a functional observational battery, or motor activity were observed after exposure to PFHxA. While no difference in survival rates in males was seen, a dose-dependent decrease in survival in PFHxA-treated female rats was observed. Hematology and serum chemistry were unaffected by PFHxA. PFHxA-related histologic changes were noted in the kidneys of the 200-mg/kg/day group females. Finally, there was no evidence that PFHxA was tumorigenic in male or female SD rats at any of the dosage levels examined.

The precautionary principle and chemicals management: The example of perfluoroalkyl acids in groundwater

“…Industry studies (e.g. Iwai and Hoberman, 2014;Klaunig et al, 2015) indicate that PFHxA is less toxic than PFOA and PFOS. Nevertheless, contamination of drinking water aquifers with short-chain PFAAs is likely because these substances are highly persistent, highly mobile in soils and aquifers (i.e.…”

Toxicological Effects of Perfluoroalkyl and Polyfluoroalkyl Substances

“…The physical and chemical properties of PFAAs, their industrial applications and production history, and their fate and transport have been well described by Kissa ( 2001 ), Prevedouros et al ( 2006 ), and Wang et al ( 2014a , b ). In brief, these chemicals are highly stable even at high temperature, nonfl ammable, not readily degraded by strong acids, alkalis or oxidizing agents, and not subject to photolysis.…”

“…By nature, perfl uoroalkyls are exceptionally stable and non-reactive under physiological conditions. In fact, this is a property of these compounds that has been exploited in commercial applications (Kissa 2001 ). Although perfl uoroalkyls, in particular, perfl uorocarboxylates, resemble free fatty acids, they are not known to be metabolized or enter into the biochemical reactions that use fatty acids Kuslikis et al 1992 ;Ophaug and Singer 1980 ).…”

“…Fluorinated surfactant products may provide unparalleled surface tension lowering in aqueous systems (Kissa 2001 ;Taylor 1999 ;Buck et al 2011aBuck et al , 2012. Polymeric products may provide oil and water repellency and stain release protection to textiles and carpet that cannot be achieved with current non-fl uorinated alternatives (Kissa 2001 ;Rao and Baker 1994 ).…”

“…Fluorinated surfactant products may provide unparalleled surface tension lowering in aqueous systems (Kissa 2001 ;Taylor 1999 ;Buck et al 2011aBuck et al , 2012. Polymeric products may provide oil and water repellency and stain release protection to textiles and carpet that cannot be achieved with current non-fl uorinated alternatives (Kissa 2001 ;Rao and Baker 1994 ). However, various perfl uoroalkyl acids (PFAAs) such as perfl uorooctane sulfonate (PFOS) and perfl uorooctanoic acid (PFOA), which have been manufactured and sold themselves and are impurities and breakdown products from numerous commercial per-and poly-fl uoroalkyl surfactant and polymeric products, have been found widely in the environment (Buck et al 2011a ).…”