Article pubs.acs.org/est First Report on the Occurrence and Bioaccumulation of Hexafluoropropylene Oxide Trimer Acid: An Emerging Concern † ‡ † † † § ∥ ∥ Yitao Pan, , Hongxia Zhang, Qianqian Cui, Nan Sheng, Leo W. Y. Yeung, Yong Guo, Yan Sun, † and Jiayin Dai*, † Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P. R. China ‡ University of Chinese Academy of Sciences, Beijing 100049, China § Man-Technology-Environment Research Centre (MTM), School of Science and Technology, Örebro University, SE-70182 Örebro, Sweden ∥ Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. China *S Supporting Information ABSTRACT: Here, we report on the occurrence of a novel perfluoroalkyl ether carboxylic acid, ammonium perfluoro-2- [(propoxy)propoxy]-1-propanoate (HFPO-TA), in surface water and common carp (Cyprinus carpio) collected from the Xiaoqing River and in residents residing near a fluoropolymer production plant in Huantai County, China. Compared with the levels upstream of the Xiaoqing River, HFPO-TA concentrations (5200−68500 ng/L) were approximately 120−1600-times higher downstream after receiving fluoropol- ymer plant effluent from a tributary. The riverine discharge of HFPO-TA was estimated to be 4.6 t/yr, accounting for 22% of total PFAS discharge. In the wild common carp collected downstream from the point source, HFPO-TA was detected in the blood (median: 1510 ng/mL), liver (587 ng/g ww), and muscle (118 ng/g ww). The log BCFblood of HFPO-TA (2.18) was significantly higher than that of PFOA (1.93). Detectable levels of HFPO-TA were also found in the sera of residents (median: 2.93 ng/mL). This is the first report on the environmental occurrence and bioaccumulation of this novel chemical. Our results indicate an emerging usage of HFPO-TA in the fluoropolymer manufacturing industry and raise concerns about the toxicity and potential health risks of HFPO-TA to aquatic organisms and humans. ■ INTRODUCTION fonate (PFOS), its salts, and related substances.6 In 2015, the Per- and polyfluoroalkyl substances (PFASs) are synthetic Risk Assessment Committee from the European Union fluorinated chemicals that have been used since the 1950s.1 The adopted the German and Norwegian proposal to restrict the manufacture, use, and marketing of PFOA, its salts, and related unique amphiphilic properties of PFASs have made them useful 7 in a wide variety of industrial applications, such as the substances. fl Since these restrictions, manufacturers have started to production of uoropolymers, surface repellent coatings, 8 fi fi 2 produce shorter-chain perfluorinated and other fluorinated metal plating, and re- ghting foam. Legacy PFASs, typically 9 long-chain (seven perfluorinated carbons or longer) perfluor- compounds as alternatives, which include functionalized fl perfluoropolyethers (PFPEs) such as perfluoroether carboxylic oalkyl carboxylic acids (PFCAs) and per uoroalkanesulfonic 4 acids (PFSAs)1 are of great concern due to their environmental and sulfonic acids (PFECAs and PFESAs). By inserting one or fl persistence, bioaccumulation potential, and possible toxicity.3,4 more ether oxygens into the per uorinated carbon backbone, it 10 As a result, global regulations have been issued to reduce the is hoped that PFECAs and PFESAs are more degradable and 11−13 production and use of these compounds.3 In 2006, eight major have replaced PFCAs and PFSAs in many applications. In fluorochemical companies participated in the 2010/2015 chrome plating, chlorinated polyfluorinated ether sulfonic acids Perfluorooctanoate (PFOA) Stewardship Program proposed by the US Environmental Protection Agency, which aimed to Received: May 2, 2017 eliminate the production and emission of PFOA by 2015.5 In Revised: July 31, 2017 2009, the Stockholm Convention on Persistent Organic Accepted: August 7, 2017 Pollutants initiated regulation of the use of perfluorooctanesul- Published: August 7, 2017 © 2017 American Chemical Society 9553 DOI: 10.1021/acs.est.7b02259 Environ. Sci. Technol. 2017, 51, 9553−9560 Environmental Science & Technology Article (6:2 and 8:2 Cl-PFESAs) have been used as mist suppressants to replace PFOS in China11 and have since been widely − detected in abiotic and biotic environments.11,14 18 In fluoropolymer manufacturing, certain PFECAs, such as perfluoro-2-propoxypropanoic acid (HFPO-DA), have been used as an alternative to PFOA. Since 2010, the ammonium salt of HFPO-DA (GenX produced by DuPont)12 has been produced at 10−100 tons per year in Europe,13 and has subsequently been observed in river waters downstream of fluorochemical industrial parks in Germany (107.6 ng/L),19 China (3825 ng/L),19 and the U.S. (631 ng/L).20 In addition, several other structurally similar chemicals have also been identified in the U.S., suggesting varied and widespread usage of PFECA homologues.10,20 Hexafluoropropylene oxide (HFPO) is a well-known key compound in organofluorine chemistry.21 Including HFPO- DA, which is the dimer acid of HFPO (structure shown in Figure S1), oligomeric HFPO can be applied as a monomer or intermediate in the synthesis of fluorinated chemicals.21 The trimer acid of HFPO, HFPO-TA (Figure S1), is used as a Figure 1. Sampling sites in Xiaoqing River. processing aid in the manufacture of fluorinated polymers, such as polytetrafluoroethylene and polyvinylidene fluoride,22 and is Common carp (Cyprinus carpio) were captured in the area an important building block in the synthesis of other between S12−S13 on December 1, 2015 (n = 15). Information fluorinated products, including surface-active agents,23 oil- on gender, body weight, and length can be found in Table S3. − repellent agents,24 ionic liquids,25 and industrial additives.26 28 Approximately 2−4 mL of whole blood was collected Available information on the physical and chemical properties immediately in EDTA-coated vacutainer tubes (BD Bioscien- of HFPO-TA are shown in Table S1. However, information is ces, USA). Liver and muscle samples were carefully dissected scarce with regard to its annual production, environmental from the fish, wrapped with aluminum foil, and maintained at occurrence, wildlife or human exposure, bioaccumulation −20 °C. potential, and toxic effects. Human subjects (22 male and 26 female) were recruited at In the present investigation, water and fish samples were Huantai County Hospital, located 8 km from the fluoropolymer collected from various sites in Xiaoqing River, China. Elevated plant. Participants were residents recruited at their first concentrations of PFCAs have been reported previously in presentation to the hospital in January 2016. All subjects had water19,29 and sediment samples of Xiaoqing River,30 which are lived in Huantai for at least two years and had never worked in likely due to discharge from one of the largest fluoropolymer the fluoropolymer plant. Blood samples were centrifuged production facilities in Asia,29 which has a reported annual immediately after collection with sera transferred and stored production of approximately 37000 t of polytetrafluoroethylene at −80 °C until analysis. The research protocol was approved (PTFE), 500 t of perfluorinated ethylene-propylene copoly- by the Ethics Committee of the Institute of Zoology, Chinese mers, 300 t of polyvinylidenefluoride (PVDF), and 40 t of Academy of Sciences, and the study hospital. ammonium perfluorooctanoate.31 Human blood samples from Sample Extraction. The water and biota samples were 32,33 local residents in Huantai County, where the fluoropolymer extracted based on previously published methods. Details production facility is located, were also collected. The of the extraction method on different matrices are provided in objectives of the present investigation were (1) to investigate the Supporting Information (SI). In brief, water samples were whether novel alternative HFPO-TA was present in freshwater extracted using a solid phase extraction (SPE) cartridge 32 and wild freshwater fish of Xiaoqing River, and (2) if so, to (Phenomenex strata X-AW, 200 mg/6 mL), whereas fish determine the tissue distribution and bioaccumulation potential blood, fish liver, and human serum were extracted using an ion- 33 in wild fish and (3) evaluate human exposure to HFPO-TA as pair extraction method. An alkaline digestion method was 32 well as other legacy PFASs in local residents. used for fish muscle samples. Additional cleanup using the SPE method was applied to fish liver and muscle samples. ■ MATERIALS AND METHODS Instrument Analysis. Target PFASs (structures shown in Figure S1), including PFCAs (C4−C14), PFSAs (C4, C6, C8), Sample Collection. Xiaoqing River is located in Shandong and Cl-PFESAs (4:2. 6:2, 8:2), were quantified using an Province, China, with a length of approximately 233 km and a Acquity UPLC coupled to a Xevo TQ-S triple quadrupole mass catchment area of 13000 km2. Parallel to the Yellow River, spectrometer (Waters, Milford, MA, USA). Because of the poor Xiaoqing River flows through four industrialized cities (Jinan, sensitivity (limit of quantification (LOQ): 5−20 ng/mL) of Binzhou, Zibo, and Dongying) before finally entering Laizhou HFPO-TA and HFPO-DA with the Xevo TQ-S, they were Bay of the Bohai Sea. From November 29 to December 1 of quantified using an API 5500 triple-quadrupole mass 2015, a total of 18 water samples were collected upstream (sites spectrometer (AB SCIEX, Framingham, MA, USA), which S1−S6), from the tributary receiving fluoropolymer plant showed much better quantification limits (0.05−0.1 ng/mL). effluent (sites S7−S10), and downstream (sites S11−18) of Multiple reaction monitoring (MRM) in ESI− mode was used Xiaoqing River (Figure 1 and Table S2). Approximately 1 L of in both mass spectrometers. Chromatographic separation was water from a depth of 1 m was collected in methanol-rinsed accomplished using an Acquity BEH C18 column (100 mm × polypropylene bottles and stored at −20 °C until analysis. 2.1 mm, 1.7 μm, Waters, MA, USA) with mobile phases of 2 9554 DOI: 10.1021/acs.est.7b02259 Environ.