title: Microbial toxicity and biodegradability of perfluorooctane sulfonate (PFOS) and shorter chain perfluoroalkyl and polyfluoroalkyl substances (PFASs).
abstract: Perfluorooctane sulfonate (PFOS) and related perfluoroalkyl and polyfluoroalkyl substances (PFASs) are emerging contaminants that have been widely applied in consumer and industrial applications for decades. However, PFOS has raised public concern due to its high bioaccumulative character, environmental persistence, and toxicity. Shorter PFASs such as perfluorobutane sulfonate (PFBS) and polyfluoroalkyl compounds have been proposed as alternatives to PFOS but it is unclear whether these fluorinated substances pose a risk for public health and the environment. The objective of this research was to investigate the microbial toxicity and the susceptibility to microbial degradation of PFOS and several related fluorinated compounds, i.e., short-chain perfluoroalkyl and polyfluoroalkyl sulfonic and carboxylic acids. None of the compounds tested were toxic to the methanogenic activity of anaerobic wastewater sludge even at very high concentrations (up to 500 mg L-1). All PFASs evaluated were highly resistant to microbial degradation. PFOS was not reductively dehalogenated by the anaerobic microbial consortium even after very long periods of incubation (3.4 years). Similarly, the tested short chain perfluoroalkyl substances (i.e., PFBS and trifluoroacetic acid) and a polyfluoroalkyl PFOS analogue, 6 : 2 fluorotelomer sulfonic acid (FTSA) were also resistant to anaerobic biodegradation. Likewise, no conclusive evidence of microbial degradation was observed under aerobic conditions for any of the short-chain perfluoroalkyl and polyfluoroalkyl carboxylic acids tested after 32 weeks of incubation. Collectively, these results indicate that PFOS and its alternatives such as short chain perfluoroalkyl sulfonates and carboxylates and their polyfluorinated homologues are highly resistant to microbial degradation.
authors.affiliation: Department of Chemical and Environmental Engineering, The University of Arizona, P.O. Box 210011, Tucson, AZ 85721-0011, USA. vochoa@usfq.edu.ec and Universidad San Francisco de Quito, Colegio de Ciencias e Ingeniería, El Politécnico, Diego de Robles y Vía Interoceánica, 17-1200-841, Quito, Ecuador.
authors.forename: Valeria
authors.initials: V
authors.lastname: Ochoa-Herrera
authors.affiliation: Department of Chemical and Environmental Engineering, The University of Arizona, P.O. Box 210011, Tucson, AZ 85721-0011, USA. vochoa@usfq.edu.ec.
authors.forename: Jim A
authors.initials: JA
authors.lastname: Field
authors.affiliation: Department of Chemical and Environmental Engineering, The University of Arizona, P.O. Box 210011, Tucson, AZ 85721-0011, USA. vochoa@usfq.edu.ec and Centro de Investigación en Materiales Avanzados (CIMAV), Ave. Miguel de Cervantes 120, Industrial Chihuahua, 31109 Chihuahua, Mexico.
authors.forename: Antonia
authors.initials: A
authors.lastname: Luna-Velasco
authors.affiliation: Department of Chemical and Environmental Engineering, The University of Arizona, P.O. Box 210011, Tucson, AZ 85721-0011, USA. vochoa@usfq.edu.ec.
authors.forename: Reyes
authors.initials: R
authors.lastname: Sierra-Alvarez
mesh_terms: D017738:Alkanesulfonic Acids / Q000737:chemistry / Q000378:metabolism*; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D003470:Culture Media; D005466:Fluorocarbons / Q000737:chemistry / Q000378:metabolism*; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology; D008697:Methane / Q000096:biosynthesis; D012722:Sewage / Q000737:chemistry / Q000382:microbiology; D062065:Wastewater / Q000737:chemistry / Q000382:microbiology
chemical_list: D017738:Alkanesulfonic Acids; D003470:Culture Media; D005466:Fluorocarbons; D008697:Methane; D012722:Sewage; D062065:Wastewater; C076994:perfluorooctane sulfonic acid