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Per- and Polyfluoroalkyl Substances
Published in Caitlin H. Bell, Margaret Gentile, Erica Kalve, Ian Ross, John Horst, Suthan Suthersan, Emerging Contaminants Handbook, 2019
Ian Ross, Erica Kalve, Jeff McDonough, Jake Hurst, Jonathan A L Miles, Tessa Pancras
Fluorotelomers are created using PFAIs as feedstock chemicals that are converted into fluorotelomer iodides, which adds an alkyl group (usually ethyl) to the perfluoroalkyl chain to create a fluorotelomer iodide (OECD 2018a), which is the feedstock to further modify and create hundreds (Wang et al. 2017), if not potentially thousands, of fluorotelomer molecules which are PFCA or PFPA/PFPiA precursors (Wang et al. 2014a; Wang et al. 2014b; OECD 2018a). There is a huge diversity of fluorotelomers in many products with many recently characterized in firefighting foams (Barzen-Hanson, Roberts et al., 2017).
Occurrence of Select Perfluoroalkyl Substances at US Air Force Aqueous Film-Forming Foam Release Sites Other than Fire Training Areas
Published in David M. Kempisty, Yun Xing, LeeAnn Racz, Perfluoroalkyl Substances in the Environment, 2018
R. Hunter Anderson, G. Cornell Long, Ronald C. Porter, Janet K. Anderson
Since the initial military specification requirements for AFFF, there have been numerous companies that have manufactured and supplied AFFF to the USDOD (Place and Field 2012). The exact composition of each AFFF formulation is proprietary, but they are all known to be a complex mixture of fluorinated surfactants. The PFAS within AFFF can be synthesized by either electrochemical fluorination or telomerization processes (Kissa 1994; Buck et al. 2011). The AFFF originally sold by 3M contained PFAS synthesized by electrochemical fluorination and therefore contained fully fluorinated perfluoroalkyl sulfonic acids (PFSA), such as perfluorooctane sulfonate (PFOS) and other CF2 homologues, as well as various perfluoroalkyl sulfonamides and their derivatives (Buck et al. 2011; Backe et al. 2013). AFFF formulations synthesized via telomerization (all other manufacturers), however, contain structurally distinct PFAS; the carbon chains are not fully fluorinated, and instead have homologues of varying C2F4 units and are known to contain a highly diverse suite of fluorotelomers (Buck et al. 2011; Backe et al. 2013). The fluorotelomers have been shown to exclusively degrade to perfluorooctoanoic acid (PFOA) and other perfluoroalkyl carboxylic acids (PFCAs) in microcosm and computational studies (Wallington et al. 2006; Wang et al. 2011; Weiner et al. 2013; Jackson et al. 2013). Conversely, perfluoroalkyl sulfonamides and their derivatives can degrade to PFOS and other PFSAs (Houtz et al. 2013; Avendaño and Liu 2015). Importantly, these “precursor” compounds ultimately result in the formation of specific PFAAs (either PFCAs or PFSAs) in situ depending on the applicable source of PFAS released to the environment; note that traditionally precursors have been defined as any PFAS that results in the production of a PFCA or PFSA with ≥7 or ≥6 perfluoroalkyl carbons, respectively (OECD 2013). Efforts to reverse engineer the chemical composition of AFFF stocks and elucidate all degradation pathways, as well as to account for the entire mass balance of PFAS in environmental samples, are ongoing (e.g., Houtz et al. 2013; Barzen-Hanson and Field 2015).
A critical review on the bioaccumulation, transportation, and elimination of per- and polyfluoroalkyl substances in human beings
Published in Critical Reviews in Environmental Science and Technology, 2023
Yao Lu, Ruining Guan, Nali Zhu, Jinghua Hao, Hanyong Peng, Anen He, Chunyan Zhao, Yawei Wang, Guibin Jiang
Compared to the legacy PFAS, reports on the concentrations of emerging PFAS in humans are relatively scarce. 6:2 Chlorinated fluoroalkyl ether sulfonic acid (6:2 Cl-PFESA), which is the predominant compound of product F-53B, has been widely used in China as mist suppressant. It is the most studied emerging PFAS congeners thus far, with studies showing that it can be widely detected in the human population, including pregnant women, fetus, occupational workers, general population, and high fish consumers. The levels of 6:2 Cl-PFESA in the human body vary depending on the sample conditions (Munoz et al., 2019; Shi et al., 2016; Wang et al., 2019). Another emerging PFAS congener that has been widely studied is ADONA, which is used as processing aids in the manufacture of fluoropolymers. Its detection frequency and exposure levels are lower than those of 6:2 Cl-PFESA in human body. Fromme et al investigated the concentration of ADONA in a total of 396 plasma samples collected from residents near a plant that used ADONA in South Germany. The results showed that ADONA was detected in only a few samples at a low concentration (0.2 ng/mL) (Fromme et al., 2017). The human exposure of other emerging PFAS, such as 6:2 fluorotelomer sulfonic acid (6:2 FTSA), 8:2 Cl-PFESA, Gen-X, perfluoro-2-methoxyacetic acid, and PFO4DA, has also been reported (Lu et al., 2021; Yao et al., 2020).
Heterogeneous photocatalytic decomposition of per- and poly-fluoroalkyl substances: A review
Published in Critical Reviews in Environmental Science and Technology, 2020
Qingbo Sun, Chunyan Zhao, Terry J. Frankcombe, Hong Liu, Yun Liu
Per- and poly-fluoroalkyl substances (PFASs) are the collective name for several thousands of different types of fluorinated compounds including perfluoroalkyl sulfonic acid, perfluoroalkyl carboxylic acid, perfluoroalkyl sulfonamide, (n:2) fluorotelomer sulfonic acid and others. They were firstly developed by the American navy and the Minnesota Mining and Manufacturing (3M) corporation in 1947. Since then, PFASs have been manufactured and broadly used in aqueous fire-fighting foams, nonstick cookware, stain protection, food packaging, surfactants, and emulsifiers etc. Despite their widespread use in the past seventy years, the health and environmental effects of PFASs are gradually emerging. It is found that the concentration of PFASs has reached up to ∼ μg/L in oceanic water (Yamashita et al., 2005). PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate) are found to be associated with sexual maturation, thyroid disease and even cancer incidence (Melzer, Rice, Depledge, Henley, & Galloway, 2010; Lopez-Espinosa et al., 2011; Barry, Winquist, & Steenland, 2013). PFASs have already become a global issue as environmental contaminants. Many countries and international organizations are thus now aiming to reduce, replace or even completely ban the use of PFASs (Ministry of the Environment of Japan, 2013; Ritscher et al., 2018; https://www.epa.gov/pfas). For instance, Australia has recently initiated a special remediation research program to minimize PFASs in the environment, remove them from contaminated soil, groundwater and solid waste, and replace them by developing alternatives (https://www.grants.gov.au/?event=public.FO.show&FOUUID=7F361450-BE46-18B4-7A113D38FA2EA993; https://www.arc.gov.au/news-publications/media/media-releases/new-research-program-tackle-pfas). Among these strategies, the removal of PFASs from our environment is a priority task in order to relieve the pressure brought thereof.