title: Global emission inventories for C4-C14 perfluoroalkyl carboxylic acid (PFCA) homologues from 1951 to 2030, part II: the remaining pieces of the puzzle.
abstract: We identify eleven emission sources of perfluoroalkyl carboxylic acids (PFCAs) that have not been discussed in the past. These sources can be divided into three groups: [i] PFCAs released as ingredients or impurities, e.g., historical and current use of perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA) and their derivatives; [ii] PFCAs formed as degradation products, e.g., atmospheric degradation of some hydrofluorocarbons (HFCs) and hydrofluoroethers (HFEs); and [iii] sources from which PFCAs are released as both impurities and degradation products, e.g., historical and current use of perfluorobutane sulfonyl fluoride (PBSF)- and perfluorohexane sulfonyl fluoride (PHxSF)-based products. Available information confirms that these sources were active in the past or are still active today, but due to a lack of information, it is not yet possible to quantify emissions from these sources. However, our review of the available information on these sources shows that some of the sources may have been significant in the past (e.g., the historical use of PFBA-, PFHxA-, PBSF- and PHxSF-based products), whereas others can be significant in the long-term (e.g., (bio)degradation of various side-chain fluorinated polymers where PFCA precursors are chemically bound to the backbone). In addition, we summarize critical knowledge and data gaps regarding these sources as a basis for future research.
authors.affiliation: Institute for Chemical and Bioengineering, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland.
authors.forename: Zhanyun
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Applied Environmental Science (ITM), Stockholm University, SE-10691 Stockholm, Sweden.
authors.forename: Ian T
authors.initials: IT
authors.lastname: Cousins
authors.affiliation: Institute for Chemical and Bioengineering, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland. Electronic address: martin.scheringer@chem.ethz.ch.
authors.forename: Martin
authors.initials: M
authors.lastname: Scheringer
authors.affiliation: E.I. du Pont de Nemours & Co. Inc., DuPont Chemicals and Fluoroproducts, 974 Centre Road, CRP 702-2211B, Wilmington, DE 19880-0702, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Buck
authors.affiliation: Institute for Chemical and Bioengineering, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland.
authors.forename: Konrad
authors.initials: K
authors.lastname: Hungerbühler
mesh_terms: D002264:Carboxylic Acids / Q000032:analysis* / Q000737:chemistry; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000032:analysis* / Q000266:history*; D005466:Fluorocarbons / Q000032:analysis* / Q000737:chemistry; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans
chemical_list: D002264:Carboxylic Acids; D004785:Environmental Pollutants; D005466:Fluorocarbons
keywords: Global emission inventory; Hydrofluorocarbons; Hydrofluoroethers; Perfluoroalkyl carboxylic acids (PFCAs); Side-chain fluorinated polymers; Substances based on perfluoroalkane sulfonyl fluorides (PASFs)