Environ. Sci. Technol. 2010, 44, 7717–7722
Inhalation Exposure to Fluorotelomer Alcohols Yield Perfluorocarboxylates in Human Blood? H E L E N A N I L S S O N , * ,† A N N A K Ä R R M A N , † ANNA ROTANDER,† BERT VAN BAVEL,† ¨ M,† AND GUNILLA LINDSTRO H Å K A N W E S T B E R G †,‡ Man-Technology-Environment (MTM) Research Centre, ¨ rebro University, SE-701 82 O ¨ rebro, Sweden, and O Department of Occupational and Environmental Medicine, ¨ rebro University Hospital, SE-701 85 O ¨ rebro, Sweden O
Received June 9, 2010. Revised manuscript received August 26, 2010. Accepted August 30, 2010.
Levels of perfluorinated carboxylates (PFCAs) in different environmental and biological compartments have been known for some time, but the routes of exposure still remain unclear. The opinions are divergent whether the exposure to general populations occurs mainly indirect through precursor compounds or direct via PFCAs. Previous results showed elevated blood levels of PFCAs in ski wax technicians compared to a general population. The objective of this follow-up study was to determine concentrations of PFCAs, perfluorosulfonates (PFSAs), and fluorotelomer alcohols (FTOHs), precursor compounds that are known to degrade to PFCAs, in air collected in the breathing zone of ski wax technicians during work. We collected air samples by using ISOLUTE ENV+ cartridges connected to portable air pumps with an air flow of 2.0 L min-1. PFCAs C5-C11 and PFSAs C4, C6, C8, and C10 were analyzed using LCMS/MS and FTOHs 6:2, 8:2, and 10:2 with GC-MS/MS. The results show daily inhalation exposure of 8:2 FTOH in µg/m3 air which is up to 800 times higher than levels of PFOA with individual levels ranging between 830-255000 ng/m3 air. This suggests internal exposure of PFOA through biotransformation of 8:2 FTOH to PFOA and PFNA in humans.
Introduction Taves et al. discovered in 1968 (1) that blood of the general population contained organic fluorinated compounds, and in 2001 one of those chemicals was confirmed as perfluorooctanoic acid (PFOA) (2). Since then perfluorinated carboxylic acids (PFCAs) have been found in humans, biota, and diverse environmental compartments all over the globe (3, 4) and it is of great concern to reveal the sources of human exposure to PFCAs. However, which route of transport is the dominating for the global transport of perfluorinated chemicals (PFCs) is still not elucidated with some studies pointing to oceanic transport (5-7) and others stating the significance of atmospheric transport of the more volatile precursors (8, 9). Although the environmental levels of PFOA have been known * Corresponding author phone: +46 19 30 12 09; fax: +46 19 30 35 66; e-mail:
[email protected]. † ¨ Orebro University. ‡ ¨ Orebro University Hospital. 10.1021/es101951t
2010 American Chemical Society
Published on Web 09/09/2010
for some years it still remains unclear what sources contribute most to the exposure of the general population. In recent years the debate is increasingly focusing on precursor compounds known to degrade to PFOA (10-12). One class of compounds who has shown to biotransform to PFCAs are fluorotelomer alcohols (FTOHs) (13, 14). Two different types of ski waxes are used; kick and glide wax. Kick wax allows the skier to kick in a forward motion in the classical style, whereas the glide wax increases the speed of the skis by lowering the friction toward the surface and preventing adhesion of snow, ice crystals, dirt, and moisture. There is a number of different wax producers and a wide range of waxes suitable for all types of conditions. Generally, the wax is chosen based on weather conditions such as temperature and snow type (artificial/natural or old/new). Cross-country skis, downhill skis, and snowboards are all optimized for maximum speed using glide waxes. The exact contents of the waxes are seldom disclosed by the manufacturers, but wax analyses show that most of the gliders available on the market contain semifluorinated n-alkanes (SFAs) and PFCAs (15). The estimated annual production of kick and glide wax is 275 tonnes globally, calculation based on information from Swix stating that their production of 110 tonnes represents 40% share of the ski wax market worldwide (16). SFAs are a group of highly fluorinated chemicals with the general formula F(CF2)n(CH2)mH. They are unbranched and even-numbered carbon chains, of which one part is fully fluorinated and the other is totally hydrogenated (17). The properties of SFAs are similar to the more well-known PFOA who act as surfactant and repel both dirt and water. The typical wax cabin for professional service technicians is a small room with poor ventilation where several persons are working simultaneously generating a great amount of airborne dust particles and fluoroorganic vapors. Application of glide waxes to snowboards, downhill skis, and cross country skis is performed using an iron of 300-375 F/150-190 °C to melt the wax onto the base of the ski (18-21). This procedure generates a lot of smoke and fumes containing a blend of gaseous organofluorine compounds (22, 23). Inhalation of organofluorine breakdown products are known to induce pulmonary edema and polymer fume fever (24, 25). Several reports describe severe respiratory symptoms after using fluorinated ski waxes (26-28). Reduced fecundity have been observed at levels of PFOA found in the general population (29) as well as developmental toxicity (30, 31) and hormonal disruption (32). In addition, FTOHs demonstrate estrogen-like properties (33). The objective of this follow-up study was to determine concentrations of PFCAs, PFSAs, and FTOHs in air collected in the respiratory zone of ski wax technicians during work. We intend to correlate those results to our previous findings of elevated blood levels of PFCAs in the same technicians (34).
Materials and Methods Study Participants. The ski wax technicians (n ) 8) are employed by the Swedish and U.S. national cross-country ski teams. The technicians’ years in the profession, team affiliations, nationalities, and ages are presented in Table S1 in Supporting Information. During the skiing season from December through to March the technicians apply fluorinated ski wax for approximately 30 h a week. None of the participants are blood donors or smokers. VOL. 44, NO. 19, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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Written informed consent was obtained from all participants at recruitment. The ethical vetting board of Uppsala, Sweden (Reference No. Dnr 2010/056) approved of the study protocol. Sampling Design. Personal sampling of particulate and gas phase in the respiratory zone was performed for all the technicians in the study (n ) 8), and a total of 24 samples were analyzed. ISOLUTE ENV+ cartridges (Biotage, Uppsala, Sweden) were connected to air pumps (SKC AirCheck 2000, Eighty Four, Pa.; MSA Escort, Pittsburgh, Pa.; or GSA SG4000, Gut Vellbruggen, Neuss, Germany) operated at an airflow rate of 2.0 L min-1. The sampling time ranged from 2.8 to 6.0 h, and samples were collected during World Cup events in Kuusamo, Finland (December 2007) followed by Val di Fiemme, Italy (January 2008), Otepaa, Estonia (February 2008), and finally in Oslo, Norway (March 2008). Chemicals and Extraction. Details of chemicals and standard compounds used in the extraction are available in the Supporting Information. Mass labeled internal standards were spiked to the SPE ENV+ cartridges. The analytes were extracted with 20 mL of 100% methanol followed by evaporation to 0.5 mL under a gentle stream of nitrogen. Performance standards for perfluorinated compounds and FTOHs were added. The extract was split to a GC-fraction in 100% methanol and an LC-fraction to which 300 µL of 2 mM ammonium acetate in water was added prior to analysis. Analysis. Levels of PFCAs perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), PFOA, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA) and PFSAs perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS) and perfluorodecane sulfonate (PFDS) were analyzed using an UPLC-MS/MS and 6:2 FTOH, 8:2 FTOH, and 10:2 FTOH were analyzed using GC-MS/MS. The Acquity UPLC system was coupled to a Quattro Premier XE (Waters Corporation, Midford) with an atmospheric electrospray interface operating in negative ion mode (ES-MS/MS). Separation was performed on an Acquity BEH C18 2.1 × 50 mm, 1.7 µm kept at 50 °C. A PFCs isolator column (Waters Corporation, Midford) was inserted between the pump and injector to retain any fluorochemicals originating from the UPLC system. Injection volume was 10 µL, and the flow rate was set to 400 µL min-1. We used multiple reaction monitoring of molecular anion [M-H]- for PFCAs and [M]- for PFSAs and measuring the product ions [M-COOH]- and [FSO3]- for carboxylates and sulfonates, respectively. Analysis of FTOHs was performed using a GC coupled to a Quattro Micro MS/MS with chemical ionization (CI) operating in positive mode. A single ion recording (SIR) was used for measuring telomer alcohols, and the results were further confirmed using multiple reaction monitoring (MRM). Injections (1 µL) were performed with pulse pressure 40 psi and in splitless mode with an injector temperature of 250 °C. Helium was used as carrier gas at a flow rate of 1.0 mL min-1, and methane was used as reagent gas. The analytes were separated on a Supelcowax10 column (Supelco, St. Louis, MO, U.S.) (30 m × 0.25 mm i.d. × 0.25 µm film thickness). The molecular ion [M+H]+ was used for quantification of FTOHs. MRM-transitions used as qualifiers and instrumental details of UPLC gradient program and GC oven program are provided in Table S2 in the Supporting Information. Quality Assurance. Quantification was performed using the internal standard method and mass labeled standards, the compounds lacking a mass labeled match were quantified using the compound closest in retention time. Analytes were quantified using a seven point calibration curve with a relative standard deviation (RSD) of the relative response factors
