Compound degraded:Perfluorooctane Sulfonate (PFOS)

General Description (About POP compound)

Perfluorooctanesulfonic acid (PFOS) (conjugate base perfluorooctanesulfonate) is an anthropogenic (human-made) fluorosurfactant, now regarded as a global pollutant. Perfluorooctanesulfonyl fluoride (POSF) was synthesized as a polymerization starting material. POSF-based polymers have been used in a wide variety of products such as waterproofing, textiles, and fire protection. Other PFCs (including small amounts of PFOA) can also form as side-reaction by-products in the synthesis of POSF (e.g., perfluorooctane sulfonamide, PFOSA), or form as degradation products during its reaction to create the intermediate reacting monomers, n-methylperfluorooctanesulfonamidoethanol (MeFOSE) and n-ethylperfluorooctanesulfonamidoethanol (EtFOSE), or form in the final product (e.g., perfluorooctane sulfonate, PFOS)

Biodegradation pathway

Publications

Abstract Title Authors Article Link
The production, use, environmental fate, occurrence, and toxicity of perfluoroalkylated substances have been reviewed. Although only a limited number of essential physicochemical data are available, thus hampering a complete assessment of the environmental fate of PFAS, it has become clear that PFAS behave differently from other nonpolar organic micropollutants. PFAS are present in environmental media in urbanized areas both with and without fluorochemicals production sites. The presence of PFOS at levels above the limit of detection has been demonstrated in almost all organisms sampled in a global survey as well as in both nonexposed and exposed human populations. The acute and chronic ecotoxicity of PFOS, PFOA, and 8:2 FTOH to aquatic organisms is moderate to low. Acute toxicity to rodents is also low. PFOS concentrations in effluents have been reported that approach indicative target values derived from available aquatic toxicity data. PFOA has been found to be weakly carcinogenic. This review shows the importance of the perfluoroalkylated substances for the environment and the necessity to fill the current gaps in knowledge of their environmental fate and effects. Environmental and Toxicity Effects of Perfluoroalkylated Substances Hesker et al., 2003 Link
The continuous production and use in certain parts of the world of perfluoroalkyl sulfonamide derivatives that can degrade to perfluorooctane sulfonic acid (PFOS) has called for better understanding of the environmental fate of these PFOS precursors. Aerobic soil biotransformation of N-ethyl perfluorooctane sulfonamide (EtFOSA, also known as Sulfluramid) was quantitatively investigated in semi-closed soil microcosms over 182 d for the first time. The apparent soil half-life of EtFOSA was 13.9 ± 2.1 d and the yield to PFOS by the end of incubation was 4.0 mol%. A positive identification of a previously suspected degradation product, EtFOSA alcohol, provided strong evidence to determine degradation pathways. The lower mass balance in sterile soil than live soil suggested likely strong irreversible sorption of EtFOSA to the test soil. The aerobic soil biotransformation of a technical grade N-ethyl perfluorooctane sulfonamidoethanol (EtFOSE) was semi-quantitatively examined, and the degradation pathways largely followed those in activated sludge and marine sediments. Aside from PFOS, major degradation products included N-Ethyl perfluorooctane sulfonamidoacetic acid (EtFOSAA), perfluorooctane sulfonamide (FOSA) and perfluorooctane sulfonamide acetic acid (FOSAA). This study confirms that aerobic soil biotransformation of EtFOSE and EtFOSA contributes significantly to the PFOS observed in soil environment, as well as to several highly persistent sulfonamide derivatives frequently detected in biosolid-amended soils and landfill leachates. Production of PFOS from aerobic soil biotransformation of two perfluoroalkyl sulfonamide derivatives Avendaño and Liu. 2014 Link
We investigated the capability of microorganisms isolated from environments polluted with perfluoroalkyl acids (PFAAs) to conduct biotransformation of these emerging pollutants. Two different microbial consortia (chemoorganoheterotrophic bacteria and total yeast and molds) were isolated from two river sediments in Saitama and Osaka, Japan, known for long term pollution with perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). The microbial consortia were incubated in the presence of added PFOS and PFOA, and decreases in concentrations of these compounds were between 46–69% and 16–36%, respectively. Decreases in concentrations were, in part, due to sorption on biomass, but defluorinated PFOS and PFOA products were not detected. However, untargeted analysis suggested the presence of several metabolites found only in samples from consortia with PFOS and PFOA but not in the control samples. Molecular formula candidates were narrowed down to two options, C18H28O5F and C21H27O4. It was assumed that these formulas were associated with unsaturated monofluorinated fatty acids and hydrocarbons with multiple unsaturated bonds or ring structures. Defluorination of perfluoroalkyl acids is followed by production of monofluorinated fatty acids Beškoski et al., 2018 Link
The anaerobic biodegradability and metabolic pathways of 8:2 fluorotelomer alcohol (8:2 FTOH) were investigated in anaerobic activated sludge. The biodegradation was well described by a double exponential decay model. 8:2 FTOH was biodegraded to poly- and perfluorinated metabolites with the release of fluoride ion. All polyfluorinated metabolites were intermediate metabolic products and could be further transformed to other metabolites, while perfluorinated metabolites were terminal products. 2H-perfluoro-2-decenoic acid (8:2 FTUA) and perfluorooctanoic acid (PFOA) were verified as the most abundant poly- and perfluorinated metabolites, respectively. Two shorter-chain perfluorinated metabolites, perfluoropentanoic acid (PFPeA) and perfluorobutyric acid (PFBA), were first reported in the biodegradation of 8:2 FTOH. However, the total molar recovery of 8:2 FTOH decreased with increasing incubation time, indicating that there might be some unknown metabolites. Thus, the anaerobic biodegradation pathways were proposed as follows: 8:2 FTOH was oxidized to 8:2 FTUA and 2-perfluorooctyl ethanoic acid (8:2 FTCA) via 2-perfluorooctyl acetaldehyde (8:2 FTAL), and then 8:2 FTUA and 8:2 FTCA were further transformed to 1-perfluoroheptyl ethanol (7:2 sFTOH) via 3-perfluoroheptyl propionic acid (7:3 acid) or/and 3-perfluoroheptyl acrylic acid (7:3 Uacid), and eventually 7:2 sFTOH was further biodegraded to PFOA and other perfluorocarboxylates containing less than eight carbons. Anaerobic biodegradation of 8:2 fluorotelomer alcohol in anaerobic activated sludge: Metabolic products and pathways Li et al., 2018 Link
This review describes the sources, fate, and transport of perfluorocarboxylates (PFCAs) in the environment, with a specific focus on perfluorooctanoate (PFO). The global historical industry-wide emissions of total PFCAs from direct (manufacture, use, consumer products) and indirect (PFCA impurities and/or precursors) sources were estimated to be 3200?7300 tonnes. It was estimated that the majority (?80%) of PFCAs have been released to the environment from fluoropolymer manufacture and use. Although indirect sources were estimated to be much less important than direct sources, there were larger uncertainties associated with the calculations for indirect sources. The physical?chemical properties of PFO (negligible vapor pressure, high solubility in water, and moderate sorption to solids) suggested that PFO would accumulate in surface waters. Estimated mass inventories of PFO in various environmental compartments confirmed that surface waters, especially oceans, contain the majority of PFO. The only environmental sinks for PFO were identified to be sediment burial and transport to the deep oceans, implying a long environmental residence time. Transport pathways for PFCAs in the environment were reviewed, and it was concluded that, in addition to atmospheric transport/degradation of precursors, atmospheric and ocean water transport of the PFCAs themselves could significantly contribute to their long-range transport. It was estimated that 2?12 tonnes/year of PFO are transported to the Artic by oceanic transport, which is greater than the amount estimated to result from atmospheric transport/degradation of precursors. Sources, Fate and Transport of Perfluorocarboxylates Prevedouros et al., 2006 Link
Human exposure to perfluorinated compounds is a worldwide phenomenon; however, routes of human exposure to these compounds have not been well-characterized. Fifty-four solid food composite samples collected as part of the Canadian Total Diet Study (TDS) were analyzed for perfluorocarboxylates and perfluorooctanesulfonate (PFOS) using a methanol extraction liquid chromatography tandem mass spectrometry method. Foods analyzed included fish and seafood, meat, poultry, frozen entrées, fast food, and microwave popcorn collected from 1992 to 2004 and prepared as for consumption. Nine composites contained detectable levels of perfluorinated compoundsfour meat-containing, three fish and shellfish, one fast food, and one microwave popcorn. PFOS and perfluorooctanoate (PFOA) were detected the most frequently; concentrations ranged from 0.5 to 4.5 ng/g. The average dietary intake of total perfluorocarboxylates and PFOS for Canadians was estimated to be 250 ng/day, using results from the 2004 TDS composites. A comparison with intakes of perfluorocarboxylates and PFOS via other routes (air, water, dust, treated carpeting, and apparel) suggested that diet is an important source of these compounds. There was a substantial margin of exposure between the toxicological points of reference and the magnitude of dietary intake of perfluorinated compounds for Canadians ? 12 years old. Dietary Exposure of Canadians to Perfluorinated Carboxylates and Perfluorooctane Sulfonate via Consumption of Meat, Fish, Fast Foods, and Food Items Prepared in Their Packaging Tittlemier et al., 2007 Link
The widespread detection of environmentally persistent perfluorinated acids (PFCAs) such as perfluorooctanoic acid (PFOA) and its longer chained homologues (C9>C15) in biota has instigated a need to identify potential sources. It has recently been suggested that fluorinated telomer alcohols (FTOHs) are probable precursor compounds that may undergo transformation reactions in the environment leading to the formation of these potentially toxic and bioaccumulative PFCAs. This study examined the aerobic biodegradation of the 8:2 telomer alcohol (8:2 FTOH, CF3(CF2)7CH2CH2OH) using a mixed microbial system. The initial measured half-life of the 8:2 FTOH was ?0.2 days mg-1 of initial biomass protein. The degradation of the telomer alcohol was monitored using a gas chromatograph equipped with an electron capture detector (GC/ECD). Volatile metabolites were identified using gas chromatography/mass spectrometry (GC/MS), and nonvolatile metabolites were identified and quantified using liquid chromatography/tandem mass spectrometry (LC/MS/MS). Telomer acids (CF3(CF2)7CH2COOH; CF3(CF2)6CFCHCOOH) and PFOA were identified as metabolites during the degradation, the unsaturated telomer acid being the predominant metabolite measured. The overall mechanism involves the oxidation of the 8:2 FTOH to the telomer acid via the transient telomer aldehyde. The telomer acid via a ?-oxidation mechanism was further transformed, leading to the unsaturated acid and ultimately producing the highly stable PFOA. Telomer alcohols were demonstrated to be potential sources of PFCAs as a consequence of biotic degradation. Biological transformation may be a major degradation pathway for fluorinated telomer alcohols in aquatic systems. Fluorotelomer Alcohol Biodegradation Yields Poly- and Perfluorinated Acids Dinglasan et al., 2004 Link
PFAS (per- and polyfluoroalkyl substances) are known to be among the most challenging organic pollutants to remediate in aquatic and terrestrial environments. (1) PFAS are found in a wide range of consumer products, they are ubiquitous in the environment, and are extremely recalcitrant. Among them, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), which have been manufactured widely and can also be formed via degradation of precursors, are the most common PFAS present in many environmental settings and are of increasing concern. (2,3) Studies indicate that PFOA and PFOS pose considerable threats to the natural environment and human health because of their wide distribution, extraordinary persistence, bioaccumulation tendencies, and potential toxicological effects. (4?7) Therefore, identifying methods to mineralize these PFAS is a topic of growing urgency. Defluorination of Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonate (PFOS) by Acidimicrobium sp. Strain A6 Huang and Jaffé. 2019 Link
Perfluorooctanesulfonate (PFOS) is a compound of global concern because of its persistence and bioaccumulation in the environment. Nevertheless, little is known of the potential for PFOS biodegradation, even though the importance of characterizing the function and activity of microbial populations detected in the environment has been discussed. This study focused on the biodegradation of PFOS by a specific microorganism. Through this study, we have identified the aerobic microorganism for the specific decomposition of PFOS from wastewater treatment sludge, as a well-known sink for environmental PFOS. This species was Pseudomonas aeruginosa strain HJ4 with a 99% similarity, a mesophilic rod type bacteria (30–37 °C). A pH range of 7–9 was determined to be optimal for the growth of strain HJ4. In this study approximately 67% over a range of concentrations (1400–1800 ?g L?1) for PFOS was biologically decomposed by P. aeruginosa after 48 h incubation. This result is reported here for the first time, which strongly pertains to the efficient biodegradation of PFOS. Therefore, our study is considered a major advancement in sustainable PFOS treatment. Biodegradation of perfluorooctanesulfonate (PFOS) as an emerging contaminant Kwon et al., 2014 Link
Polyfluoroalkyl chemicals containing perfluoroalkyl moieties have been widely used in numerous industrial and commercial applications. Many polyfluoroalkyl chemicals are potential perfluoroalkyl acid (PFAA) precursors. When they are released to the environment, abiotic and microbial degradation of non-fluorinated functionalities, polyfluoroalkyl and perfluoroalkyl moieties can result in perfluoroalkyl carboxylic (PFCAs) and sulfonic acids (PFSAs), such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). These highly persistent and ubiquitously detected PFAAs are the subjects of many regulations and actions due to their toxic profiles. In order to confidently evaluate the environmental fate and effects of these precursors and their links to PFSAs and PFCAs, we present the review into the environmental biodegradability studies carried out with microbial culture, activated sludge, soil and sediment in the past decade. First, we propose that the knowledge gap caused by the lack of direct detection of precursor chemicals in environmental samples can be bridged by laboratory investigations of important precursors such as fluorotelomer-based compounds and perfluoroalkane sulfonamido derivatives. Then we evaluate the experimental setups and methodologies, sampling and sample preparation methods, and analytical techniques that have been successfully applied. Third, we provide the most updated knowledge on quantitative and qualitative relationships between precursors and PFSAs or PFCAs, microbial degradation pathways, half-lives of precursors, defluorination potential, and novel degradation intermediates and products. In the end, we identify knowledge gaps and suggest research directions with regard to future biodegradation studies, environmental monitoring and ecotoxicological assessment of perfluoroalkyl and polyfluoroalkyl chemicals. Microbial degradation of polyfluoroalkyl chemicals in the environment: A review Liu and Avendaño. 2013 Link
Per- and polyfluoroalkyl substances (PFAS) are Synthetic Organic Compounds (SOCs) which are of current concern as they are linked to a myriad of adverse health effects in mammals. They can be found in drinking water, rivers, groundwater, wastewater, household dust, and soils. In this review, the current challenge and status of bioremediation of PFAs in soils was examined. While several technologies to remove PFAS from soil have been developed, including adsorption, filtration, thermal treatment, chemical oxidation/reduction and soil washing, these methods are expensive, impractical for in situ treatment, use high pressures and temperatures, with most resulting in toxic waste. Biodegradation has the potential to form the basis of a cost-effective, large scale in situ remediation strategy for PFAS removal from soils. Both fungal and bacterial strains have been isolated that are capable of degrading PFAS; however, to date, information regarding the mechanisms of degradation of PFAS is limited. Through the application of new technologies in microbial ecology, such as stable isotope probing, metagenomics, transcriptomics, and metabolomics there is the potential to examine and identify the biodegradation of PFAS, a process which will underpin the development of any robust PFAS bioremediation technology. Challenges and Current Status of the Biological Treatment of PFAS-Contaminated Soils Shahsavari Link
Thousands of heavily fluorinated chemicals are found in the environment, impact human and ecosystem health, and are relatively resistant to biological and chemical degradation. Their persistence in the environment is due to the inability of most microorganisms to biodegrade them. Only a very few examples of polyfluorinated compound biodegradation are known, and the reported rates are very low. This has been mostly attributed to the low chemical reactivity of the C-F bond. This Perspective goes beyond that explanation to highlight microbiological reasons why polyfluorinated compounds resist metabolism. The evolutionary and physiological impediments must be appreciated to better find, study, and harness microbes that degrade polyfluorinated compounds. Why Is the Biodegradation of Polyfluorinated Compounds So Rare? Wackett. 2021 Link
Poly- and perfluorinated chemicals, including perfluorinated alkyl substances (PFAS), are pervasive in today’s society, with a negative impact on human and ecosystem health continually emerging. These chemicals are now subject to strict government regulations, leading to costly environmental remediation efforts. Commercial polyfluorinated compounds have been called ‘forever chemicals’ due to their strong resistance to biological and chemical degradation. Environmental cleanup by bioremediation is not considered practical currently. Implementation of bioremediation will require uncovering and understanding the rare microbial successes in degrading these compounds. This review discusses the underlying reasons why microbial degradation of heavily fluorinated compounds is rare. Fluorinated and chlorinated compounds are very different with respect to chemistry and microbial physiology. Moreover, the end product of biodegradation, fluoride, is much more toxic than chloride. It is imperative to understand these limitations, and elucidate physiological mechanisms of defluorination, in order to better discover, study, and engineer bacteria that can efficiently degrade polyfluorinated compounds. Nothing lasts forever: understanding microbial biodegradation of polyfluorinated compounds and perfluorinated alkyl substances Wackett. 2021 Link
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. Microbial toxicity and biodegradability of perfluorooctane sulfonate (PFOS) and shorter chain perfluoroalkyl and polyfluoroalkyl substances (PFASs) Ochoa-Herrera et al., 2016 Link