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Background levels of Persistent Organic Pollutants in humans from Taiwan: Perfluorooctane sulfonate and perfluorooctanoic acid
Chemosphere 93 (2013) 532–537
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Background levels of Persistent Organic Pollutants in humans from Taiwan: Perfluorooctane sulfonate and perfluorooctanoic acid Jen-Yi Hsu a, Jing-Fang Hsu b, Hsin-Hui Ho a, Chow-Feng Chiang c, Pao-Chi Liao a,⇑ a
Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, 138 Sheng-Li Road, Tainan 704, Taiwan L5 Research Center, China Medical University Hospital Taichung, 138 Sheng-Li Road, Tainan 704, Taiwan c Department of Public Health, China Medical University, 138 Sheng-Li Road, Tainan 704, Taiwan Taiwan b
h i g h l i g h t s To determine the background levels of PFOS and PFOA in the Taiwanese population. Investigate the age-, gender-factors that are potentially related. To compare with various countries. We report the PFOS and PFOA levels of serum samples in the general population of Taiwan. The concentrations of PFOS and PFOA in Taiwanese serum samples were no higher than those from other countries.
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Article history: Received 18 November 2012 Received in revised form 8 June 2013 Accepted 16 June 2013 Available online 22 July 2013 Keywords: Perfluorinated compounds Perfluorooctane sulfonate (PFOS) Perfluorooctanoic acid (PFOA) Human serum Taiwan Background
a b s t r a c t Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have recently received attention due to their widespread contamination of the environment. PFOS and PFOA are stable in the environment and resistant to metabolism, hydrolysis, photolysis and biodegradation. PFOS and PFOA have been found in human blood and tissue samples from both occupationally exposed workers and the general worldwide population. This study aimed to determine the background levels of PFOS and PFOA in the Taiwanese population, investigate related factors, and compare exposure in Taiwan to that in other countries. The concentration of PFOS in the 59 serum samples collected from the general population in Taiwan ranged from 3.45 to 25.65 ng mL1 (median: 8.52), and the concentration of PFOA ranged from 1.55 to 7.69 ng mL1 (median: 3.22). There was a significant positive correlation (r = 0.51; p < 0.0001) between PFOS and PFOA concentrations. Males had higher concentrations of PFOA and PFOS than females. PFOS levels in serum increased with age. This study is the first investigation to reveal the PFOS and PFOA levels of serum samples in the general population of Taiwan. The levels of PFOS and PFOA in Taiwanese serum samples were comparable with those from other countries (PFOS: 5.0–35 ng mL1, PFOA: 1.5– 10 ng mL1). Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction Perfluorinated compounds (PFCs) are persistent environment pollutants. Due to their widespread use in manufacturing Polyvinyl chloride (PVCs) and consumer products, PFCs are common in the environment and in biota (Giesy and Kannan, 2001; Prevedouros et al., 2005; Houde et al., 2006). They have been used to manufacture popular consumer products such as nonstick and stain-resistant coatings of cookware, food containers, breathable waterproof textiles, furniture, food packing materials, and carpets
⇑ Corresponding author. Address: Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, 138 Sheng-Li Road, Tainan 704, Taiwan. Tel.: +886 6 2353535x5566; fax: +886 6 2752484. E-mail address: [email protected] (P.-C. Liao). 0045-6535/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.chemosphere.2013.06.047
(Butenhoff et al., 2006; Lau et al., 2007; US EPA, 2010). Previous research on PFCs has focused on perfluorocarboxylates (PFCAs) and perfluorosulfonates (PFSAs) (Rhoads et al., 2008; Plumlee et al., 2009; Butt et al., 2010; Lee et al., 2010; Wang et al., 2011). PFCAs and PFSAs are of particular concern because of their toxic effects, persistence in the environment, and potential for bioaccumulation (Fromme et al., 2009). The two most common PFCs found in the environment, PFOS and PFOA, contain an eight-carbon backbone. In humans, the average half-life for elimination of PFOS has been estimated at 5.4 years; PFOA’s half-life is estimated at 3.8 years (Olsen et al., 2007a). Toxicity studies in animals have demonstrated adverse health effects from PFC exposure, such as reduced body weight, hepatotoxicity, developmental toxicity, immunotoxicity and hormonal effects (Lau et al., 2007). In 2006, the US Environmental Protection
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Agency (EPA) launched the PFOA Stewardship Program. The participating companies pledged to reduce emissions and product content of PFOA, PFOA precursors and related higher homolog chemicals by 95% by 2010 and to work toward eliminating emissions and the product content of these PFCs by 2015 (US EPA, 2001). While certain PFCs, including PFOS and PFOA, are being voluntarily phased out by industry, they may still be present in older products. The primary sources of human exposure to PFOS and PFOA include drinking water, food packaging, breast milk, household dust, and chemicals in the workplace (Lau et al., 2007; D’Hollander et al., 2010; Goosey and Harrad, 2011; Kim et al., 2011). Due to its persistence and bio-accumulative properties, PFOS was added to the Stockholm Convention on Persistent Organic Pollutants in 2009 (Geneva:Stockholm Convention Secretariat, 2009). Levels of PFOS and PFOA in samples of human blood vary widely among countries. A comprehensive overview of exposure to PFCs in the general populations of different countries has been published (Fromme et al., 2009). Most data that are relevant to human exposure to PFCs are reported for relatively industrialized countries. The levels of PFOS are higher in North Americans than those in European, Asian, and Australian populations (Hemat et al., 2010). For Taiwan, levels of perfluorinated chemicals in umbilical cord blood and in a cohort of young people in a hypertension study have been reported (Lien et al., 2011; Lin et al., 2011). However, the background levels of PFOS and PFOA in the Taiwanese general population have not been investigated. The present study was designed to determine the background levels of PFOS and PFOA in the Taiwanese population and to investigate related factors.
2. Materials and methods 2.1. Study population and sample collection All of the study subjects were volunteers living in the Taichung, Taiwan. Recruitment information posted by: (1) distribute the flyers, (2) using the internet to disseminate information and (3) newspaper advertisement. Subjects were selected for this investigation according to the following criteria: (1) they had resided in the sampling area for at least the previous five years; (2) they had not been exposed to readily identifiable point sources of PFOS and PFOA, such as in the workplace; (3) they were over 18 years and under 60 years of age; and (4) they were not known to be pregnant or have illnesses or heart conditions that could increase the risks associated with having blood taken. One hundred twenty subjects from the general population were recruited in Taichung, Taiwan; subjects came from eight urban areas (Central Dist, East Dist, South Dist, West Dist, North Dist, Beitun Dist, Xitun Dist and Nantun Dist). Taichung (literally mean in Chinese is ‘‘Central Taiwan’’) is a city located in western Taiwan, with a population of just over 2.6 million people (11.5% of Taiwan), making it the third largest city on the island. Taichung’s location and population structure indicates that it provides a fair representation of the wider Taiwanese population. Matched by number, men and women were randomly sampled from each area. But, one female subject abstained from participating in this study. Finally, 59 subjects from the general population were recruited in Taichung, Taiwan, in May 2011. Among 59 subjects, 30 were males (51%) and 29 were females (49%). The average age of the 59 subjects was 41.3 ± 13.1 years (mean ± standard deviation) and ranged from 19.8 to 65.0 years. Blood samples were drawn by professional nurses and taken using chemically clean VACUETTEÒ Blood Tubes (Greiner Bio-One Inc., Austria) containing no anti-coagulants. The coagulated blood was then centrifuged to obtain serum samples, which were kept frozen at 80 °C until analysis. All samples were anonymous but
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were accompanied by data concerning the gender, age and location of residence of the donors. Informed consent was obtained from the subjects, and the study protocol was approved by the medical ethics committee of the National Cheng Kung University Hospital, Tainan, Taiwan. 2.2. Chemicals and reagents Perfluorooctanoic acid (PFOA; purity > 96%), perfluorooctyl sulfonate (PFOS; purity > 98%), and ammonium acetate were purchased from Sigma–Aldrich (St. Louis, MO, USA). The internal standard 13C4-perfluorooctanoic acid (13C4-PFOA) was purchased from Wellington Laboratories (Guelph, Ontario, Canada). Milli-Q water was obtained from a Millipore water purification system (Billeria, MA, USA). Ammonium acetate (purity: N 99% by HPLC) was purchased from Aldrich (Steinheim, Germany). Acetonitrile was LC/MS grade from Sigma–Aldrich (St. Louis, MO, USA). Methanol was LC/MS grade from J.T. Baker (Phillipsburg, NJ, USA). Disodium hydrogen phosphate was purchased from Wako Pure Chemicals (Osaka, Japan). Solid-phase extraction was performed with Octadecyl (C18) cartridges (500 mg/6 mL) from J.T. Baker. Fetal bovine serum was purchased from Thermo Scientific HyClone (South Logan, UT, USA). 2.3. Preparation of serum samples Serum samples were subjected to a clean-up procedure using the dispersive carbon method described by (Vassiliadou et al., 2010). One half milliliter of blood serum was promptly pipetted into a 15-mL polypropylene centrifuge tube, and then 100 lL of the internal standard working solution (containing 10 ng mL 1 13 C4-labeled PFOA in methanol) was added. Five milliliters of acetonitrile was added, and the sample was vortex-mixed for 1 min. Finally, the sample was centrifuged at approximately 8500g for 15 min to clarify the supernatant. The organic phase was evaporated until dry in a flash evaporator, and the residue obtained was dissolved in 5 mL of phosphate buffer solution (PB) 0.05 M, pH = 7.8. Solid-phase extraction was performed as follows. After conditioning a C18 cartridge with 2 mL of methanol and 5 mL of water, the residue dissolved in phosphate buffer was passed through the cartridge. The cartridge was then washed with 5 mL of water, and PFOS and PFOA were eluted from the cartridge with 5 mL of methanol. The flow rate of the cartridge was approximately 1–2 drops per second. The organic phase was evaporated until dry in a flash evaporator. The dry residue was then dissolved in 200 lL of the HPLC mobile phase (MeOH – 5 mM ammonium acetate (20:80, v/v). 2.4. PFOS and PFOA analysis All sample extracts were analyzed by liquid chromatography– tandem mass spectrometry (LC–MS/MS) with electrospray ionization (ESI) operating in negative mode. The extracts (20 lL injection volume) were chromatographed on a ZORBAX Eclipse XDB-C18 column (3.5 lm, 50 mm 2.1 mm i.d., Angilent) using Angilent 1200 HPLC. The mobile phase was A: 2.0 mM ammonium acetate in water and B: methanol. The solvent gradient started at 60% A and 40% B (flow rate of 0.25 mL min1) and then increased to 75% B by 0.5 min, and then increased to 100% B by 5 min, held for 2.5 min, and then down to 30% B by 0.1 min, held for 1.9 min. The HPLC was interfaced to a triple quadrupole API 5000 (Applied Biosystems) equipped with a TURBO VTM ion source operating in negative ion mode. The source temperature was maintained at 300 °C and the spray voltage at 4500 V. The analyses were performed with a multiple reaction monitoring (MRM) method that monitored two mass transitions (parent ion/product ion) for each analyte.
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PFOS : 499 ! 99; PFOA : 413 ! 369; 13
499 ! 130 413 ! 169
C4 PFOA : 417 ! 372
The values of the voltages applied to the tube lense offset and the collision cell were optimized by direct infusion of a solution containing the analytes. Confirmation of analyte identity was based on retention time and on the relative response of the secondary mass transition to the primary mass transition. 2.5. Quantification and quality assurance Quantification was performed using the isotope-labeled internal standard method. To achieve lower detection limits and minimize background signal due to contamination, all accessible polytetraflurethylene (PTFE) materials were removed from the instruments and apparatus. The containers were extracted with methanol and analyzed for PFOS and PFOA. No contamination of PFOS and PFOA was found above the limit of quantification (LOQ) in containers, solution or chemical regents used in the analysis. One blank sample (Milli-Q water) was extracted with each batch of 15 samples to check for possible laboratory contamination and interference. The syringes and filters used in sample preparation were all washed by methanol before analyzing the sample. The LOQ were determined as signal/noise (S/N) ratio of 10. More specifically, LOQ was calculated at 0.25 ng mL1 for both PFOS and PFOA. The cattle serum samples were spiked with 4 ng mL1 of target standards to evaluate the recovery. The extraction recovery ranges of PFOS and PFOA were 73.9–106% and 100–121%, respectively.
Fig. 1. Correlation between the PFOS and PFOA concentrations, r = 0.51, p < 0.001, N = 59.
2.6. Statistics The Shapiro–Wilk normality test was used to determine whether a random sample of the levels of PFOS and PFOA examined in this study followed a normal distribution. Nonparametric Mann–Whitney U test was used to compare the serum levels of PFOS and PFOA according to gender. Differences for which p < 0.05 were considered to be statistically significant. The associations between age, gender, and concentration were evaluated by the Spearman correlation, a linear regression model. The statistical analysis was performed using the Statistica (version 6.0, StatSoft Inc., Tulsa, OK) software system.
Fig. 2. Difference between PFOS and PFOA concentrations.
3. Results PFOS and PFOA were quantified in 59 samples, all samples contained PFOS and PFOA at concentrations above the LOQ. The descriptive statistics for PFOS and PFOA are presented in Table 1. There was a strong correlation between PFOS and PFOA concentrations (Spearman r = 0.51, p < 0.0001) (Fig. 1). In general, PFOS concentrations of most samples were higher than PFOA concentrations; in only one sample was the PFOA concentration
Table 1 Serum concentrations (ng mL1) of PFOS and PFOA in Taiwanese. Male (n = 30)
Female (n = 29)
Total (n = 59) Fig. 3. Concentrations (ng mL1) of PFOS and PFOA by gender.
PFOS Range Median GM(SD)
4.67–22.61 10.23 10.64(5.10)
3.45–25.65 6.01 7.12(5.61)
3.45–25.65 8.52 8.96(5.67)
PFOA Range Median GM(SD)
2.07–7.69 3.77 3.83(1.24)
1.55–5.98 2.48 2.77(1.21)
1.55–7.69 3.22 3.27(1.32)
GM: geometric mean (ng ml1) and SD: standard deviation.
slightly higher than that of PFOS. The difference between PFOS and PFOA concentrations is shown in Fig. 2. The median of PFOS and PFOA concentrations were significantly higher (p < 0.05) in males than in females (Fig. 3). PFOS levels in serum increased with age (r = 0.39; p < 0.01), but the same phenomenon was not found for PFOA (r = 0.18; p = 0.184) (Fig. 4).
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(7.39 ng mL1 and 1.35 ng mL1) (Chan et al., 2011). The PFOS and PFOA serum concentrations in other countries are shown in Fig. 5. The levels of PFOS and PFOA in Taiwanese serum samples were comparable with those from other countries (PFOS: 5.0– 35 ng mL1, PFOA: 1.5–10 ng mL1). The uses of PFOS and PFOA are different. In the semiconductor industry, PFOS is used in multiple photolithographic chemicals including: photoacid generators (PAGs) and anti-reflective coatings (ARCs). The dominant use of PFOA is as an emulsifier for the emulsion polymerization of fluoropolymers such as polytetrafluoroethylene (PTFE or Teflon) (Lau et al., 2007). Because of their different uses, their exposure pathways are also different. In this report there was a strong correlation between PFOS and PFOA concentrations (Spearman r = 0.51, p < 0.0001) (Fig. 1). It is possibly exposure from food, drinking water or dust (Haug et al., 2011). Because PFOS and PFOA can remain in the animal and environment. The half-life of PFOS is longer than PFOA, the concentration levels of PFOS was higher than PFOA in the subjects. In Fig. 2, it was shown that the concentration levels of PFOS was higher than PFOA in the 58 people of the subjects.
4.2. Gender
Fig. 4. (A) Relationships between subject age and PFOS concentrations (N = 59, r = 0.39, p < 0.01). (B) Relationships between subject age and PFOA concentrations (N = 59, r = 0.18, p = 0.1841).
4. Discussion 4.1. Background levels of PFOS and PFOA in the Taiwanese population This study evaluated the background levels of PFOS and PFOA in 59 samples from individual volunteers in Taiwan and provides important documentation of the distribution of PFOS and PFOA levels in the general population. The data can be used to (1) evaluate the degree of PFOS and PFOA exposure in individual subjects or (2) identify subjects with an elevated exposure to PFOS and PFOA relative to background levels. The median value of PFOS (8.52 ng mL1) was higher than that of PFOA (3.22 ng mL1). This result is similar to previous biological monitoring investigations of PFOS and PFOA levels in general population groups from other countries. In the United States, there have been several reports on PFOS and PFOA concentrations in unpooled and pooled human serum samples, including those from Red Cross blood donors (Olsen et al., 2003a,b, 2005; Calafat et al., 2007; Olsen et al., 2007b, 2008). The means were generally around 5–25 ng mL1 for PFOS and 2–10 ng mL1 for PFOA. The mean concentrations of PFOS and PFOA in human serum have also been examined in Japan (6.19 ng mL1 and 4.10 ng mL1) (Harada et al., 2010), China (6.67 ng mL1 and 2.32 ng mL1) (Guo et al., 2011), Spain (7.6 ng mL1 and 1.65 ng mL1) (Ericson et al., 2007), Greece (10 ng mL1 and 2 ng mL1) (Vassiliadou et al., 2010), Australia (15.2 ng mL1 and 6.4 ng mL1) (Toms et al., 2009), Greenland (24.6 ng mL1 and 5.2 ng mL1) (Bonefeld-Jorgensen et al., 2011), German females (15 ng mL1 and 10 ng mL1), German males (25 ng mL1 and 10 ng mL1) (Wilhelm et al., 2009) and Canada
Males and females had significantly different serum concentrations of PFOA and PFOS. The levels of PFOS and PFOA in males were higher than those in females. In earlier studies, gender differences of PFOS and PFOA concentration were also found in the general population from Japan (Harada et al., 2004) and Australia (Toms et al., 2009). However, a study in Spain reported no statistically significant difference in PFOS levels between the males and females of the serum pools (Ericson et al., 2007). Females eliminate PFOA in the urine more rapidly than males; this is largely due to active renal excretion. Several studies have investigated the cause of this sex difference in elimination of PFOA in rats. Administration of probenecid (an inhibitor of the renal active secretion system for organic acids) reduced the elimination of PFOA in female rats. The elimination of PFOA in male rat is virtually unaffected by probenecid administration. Therefore, the female rat possesses an active secretory mechanism which rapidly eliminates PFOA from the body (Hanhijärvi et al., 1982). In male rats, testosterone has been shown to exert an inhibitory effect on renal excretion of PFOA (Vanden Heuvel et al., 1992). Castration of male rats increased the elimination of PFOA in the urine. This is a male specific response, as ovariectomised female rats with or without testosterone treatment had the same urinary PFOA excretion as intact females (Committee on Toxicity of Chemicals in Food Consumer Products and the Environment, 2005). Similar gender differences were reported in rats exposed to PFOA: the half-lives were longer in males than females (Kudo and Kawashima, 2003).
4.3. Age In this study, we found that concentrations of PFOS increased significantly with age, but not those of PFOA. Previous studies have reported the similar finding that PFOS concentrations in older adults were significantly higher than younger adults (Kärrman et al., 2006; Nilsson et al., 2010), but the results are not uniform throughout the literature. Researchers found an age effect for PFOA and PFOS in German females, but the same phenomenon was not found in German males (Fromme et al., 2007). There were no age differences in the concentrations of PFOA and PFOS in a Chinese population (Yeung et al., 2006). Elucidation of the effects of age on PFOS accumulation, metabolism and excretion in humans is complicated by individual variations in lifestyle.
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Fig. 5. Concentrations of PFOS and PFOA in blood samples of people from various countries (Olsen et al., 2003a; Olsen et al., 2003b; Olsen et al., 2005; Calafat et al., 2007; Ericson et al., 2007; Olsen et al., 2007; Olsen et al., 2008; Toms et al., 2009; Wilhelm et al., 2009; Harada et al., 2010; Vassiliadou et al., 2010; Bonefeld-Jorgensen et al., 2011; Chan et al., 2011; Guo et al., 2011).
5. Conclusion This study is the first investigation to document the PFOS and PFOA levels of serum samples in the general population of Taiwan. The background exposure data of the Taiwanese population can provide a scientific basis for setting up PFOS and PFOA monitoring and regulatory programs. Since all samples analyzed in the present study were acquired during 2011, it was not possible to investigate the temporal trend of PFOS and PFOA in Taiwan. This issue could be the subject of a future study and scheduled epidemiologic research in the area of perfluoroalkyls and human developmental outcomes. A significant positive correlation between PFOS and PFOA serum concentrations was observed in the present study (r = 0.49; p < 0.0001). The serum concentrations of PFOS and PFOA were significantly higher in males than in females. Higher levels of PFOS in serum samples were associated with age. Although the sampling years and the mean age of the other countries were different. The concentrations of PFOS (median: 8.52 ng mL1) and PFOA (median: 3.22 ng mL1) in Taiwanese serum samples were no higher than those from other countries (PFOS: 5.0–35 ng mL1, PFOA: 1.5–10 ng mL1). Acknowledgment This work was supported by Grants (NSC100-2113-M-006-002MY3) from the National Science Council of Taiwan. References Bonefeld-Jorgensen, E.C., Long, M., Bossi, R., Ayotte, P., Asmund, G., Kruger, T., Ghisari, M., Mulvad, G., Kern, P., Nzulumiki, P., Dewailly, E., 2011. Perfluorinated compounds are related to breast cancer risk in Greenlandic Inuit: a case control study. Environ. Health 10. Butenhoff, J.L., Olsen, G.W., Pfahles-Hutchens, A., 2006. The applicability of biomonitoring data for perfluorooctanesulfonate to the environmental public health continuum. Environ. Health Perspect. 114, 1776–1782. Butt, C.M., Muir, D.C.G., Mabury, S.A., 2010. Elucidating the pathways of poly- and perfluorinated acid formation in rainbow trout. Environ. Sci. Technol. 44, 4973– 4980. Calafat, A.M., Wong, L.-Y., Kuklenyik, Z., Reidy, J.A., Needham, L.L., 2007. Polyfluoroalkyl chemicals in the US population: data from the National Health and Nutrition Examination Survey (NHANES) 2003–2004 and comparisons with NHANES 1999–2000. Environ. Health Perspect. 115. Chan, E., Burstyn, I., Cherry, N., Bamforth, F., Martin, J.W., 2011. Perfluorinated acids and hypothyroxinemia in pregnant women. Environ. Res. 111, 559–564.
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J.-Y. Hsu et al. / Chemosphere 93 (2013) 532–537 2002–2003, in relation to age, gender, and region. Environ. Sci. Technol. 40, 3742–3748. Kim, S.-K., Lee, K.T., Kang, C.S., Tao, L., Kannan, K., Kim, K.-R., Kim, C.-K., Lee, J.S., Park, P.S., Yoo, Y.W., Ha, J.Y., Shin, Y.-S., Lee, J.-H., 2011. Distribution of perfluorochemicals between sera and milk from the same mothers and implications for prenatal and postnatal exposures. Environ. Pollut. 159, 169– 174. Kudo, N., Kawashima, Y., 2003. Toxicity and toxicokinetics of perfluorooctanoic acid in humans and animals. J. Toxicol. Sci. 28, 49–57. Lau, C., Anitole, K., Hodes, C., Lai, D., Pfahles-Hutchens, A., Seed, J., 2007. Perfluoroalkyl acids: a review of monitoring and toxicological findings. Toxicol. Sci.: Off. J. Soc. Toxicol. 99, 366–394. Lee, H., D’eon, J., Mabury, S.A., 2010. Biodegradation of polyfluoroalkyl phosphates as a source of perfluorinated acids to the environment. Environ. Sci. Technol. 44, 3305–3310. Lien, G.W., Wen, T.W., Hsieh, W.S., Wu, K.Y., Chen, C.Y., Chen, P.C., 2011. Analysis of perfluorinated chemicals in umbilical cord blood by ultra-high performance liquid chromatography/tandem mass spectrometry. J. Chromatogr. B, Anal. Technol. Biomed. Life Sci. 879, 641–646. Lin, C.-Y., Wen, L.L., Lin, L.-Y., Wen, T.-W., Lien, G.-W., Chen, C.-Y., Hsu, S.H.J., Chien, K.-L., Sung, F.-C., Chen, P.-C., Su, T.-C., 2011. Associations between levels of serum perfluorinated chemicals and adiponectin in a young hypertension cohort in Taiwan. Environ. Sci. Technol. 45, 10691–10698. Nilsson, H., Kärrman, A., Westberg, H., Rotander, A., van Bavel, B., Lindström, G., 2010. A time trend study of significantly elevated perfluorocarboxylate levels in humans after using fluorinated ski wax. Environ. Sci. Technol. 44, 2150–2155. Olsen, G.W., Church, T.R., Miller, J.P., Burris, J.M., Hansen, K.J., Lundberg, J.K., Armitage, J.B., Herron, R.M., Medhdizadehkashi, Z., Nobiletti, J.B., O’Neill, E.M., Mandel, J.H., Zobel, L.R., 2003a. Perfluorooctanesulfonate and other fluorochemicals in the serum of American Red Cross adult blood donors. Environ. Health Perspect. 111. Olsen, G.W., Hansen, K.J., Stevenson, L.A., Burris, J.M., Mandel, J.H., 2003b. Human donor liver and serum concentrations of perfluorooctanesulfonate and other perfluorochemicals. Environ. Sci. Technol. 37, 888–891. Olsen, G.W., Huang, H.-Y., Helzlsouer, K.J., Hansen, K.J., Butenhoff, J.L., Mandel, J.H., 2005. Historical comparison of perfluorooctanesulfonate, perfluorooctanoate, and other fluorochemicals in human blood. Environ. Health Perspect. 113. Olsen, G.W., Burris, J.M., Ehresman, D.J., Froehlich, J.W., Seacat, A.M., Butenhoff, J.L., Zobel, L.R., 2007a. Half-life of serum elimination of perfluorooctanesulfonate, perfluorohexanesulfonate, and perfluorooctanoate in retired fluorochemical production workers. Environ. Health Perspect. 115.
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Olsen, G.W., Burris, J.M., Ehresman, D.J., Froelich, J.W., Seacat, A.M., Butenhoff, J.L., Zobel, L.R., 2007b. Half-life of serum elimination of perfluorooctanesulfonate, perfluorohexanesulfonate, and perfluorooctanoate in retired fluorochemical production workers. Environ. Health Perspect. 115, 1298–1305. Olsen, G.W., Mair, D.C., Church, T.R., Ellefson, M.E., Reagen, W.K., Boyd, T.M., Herron, R.M., Medhdizadehkashi, Z., Nobiletti, J.B., Rios, J.A., Butenhoff, J.L., Zobel, L.R., 2008. Decline in perfluorooctanesulfonate and other polyfluoroalkyl chemicals in American Red Cross adult blood donors, 2000–2006. Environ. Sci. Technol. 42, 4989–4995. Plumlee, M.H., McNeill, K., Reinhard, M., 2009. Indirect photolysis of perfluorochemicals: hydroxyl radical-initiated oxidation of N-ethyl perfluorooctane sulfonamido acetate (N-EtFOSAA) and other perfluoroalkanesulfonamides. Environ. Sci. Technol. 43, 3662–3668. Prevedouros, K., Cousins, I.T., Buck, R.C., Korzeniowski, S.H., 2005. Sources, fate and transport of perfluorocarboxylates. Environ. Sci. Technol. 40, 32–44. Rhoads, K.R., Janssen, E.M.L., Luthy, R.G., Criddle, C.S., 2008. Aerobic biotransformation and fate of N-ethyl perfluorooctane sulfonamidoethanol (N-EtFOSE) in activated sludge. Environ. Sci. Technol. 42, 2873–2878. Toms, L.M.L., Calafat, A.M., Kato, K., Thompson, J., Harden, F., Hobson, P., Sjödin, A., Mueller, J.F., 2009. Polyfluoroalkyl chemicals in pooled blood serum from infants, children, and adults in Australia. Environ. Sci. Technol. 43, 4194–4199. US EPA, 2001. 2010/15 PFOA Stewardship Program.. US EPA, 2010. Basic Information on Perfluorooctanoic Acid (PFOA) and Fluorinated Telomers. . Vanden Heuvel, J.P., Davis, J.W., Sommers, R., Peterson, R.E., 1992. Renal excretion of perfluorooctanoic acid in male rats: inhibitory effect of testosterone. J. Biochem. Toxicol. 7, 31–36. Vassiliadou, I., Costopoulou, D., Ferderigou, A., Leondiadis, L., 2010. Levels of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) in blood samples from different groups of adults living in Greece. Chemosphere 80, 1199–1206. Wang, N., Liu, J., Buck, R.C., Korzeniowski, S.H., Wolstenholme, B.W., Folsom, P.W., Sulecki, L.M., 2011. 6:2 Fluorotelomer sulfonate aerobic biotransformation in activated sludge of waste water treatment plants. Chemosphere 82, 853–858. Wilhelm, M., Angerer, J., Fromme, H., Hölzer, J., 2009. Contribution to the evaluation of reference values for PFOA and PFOS in plasma of children and adults from Germany. Int. J. Hyg. Environ. Health 212, 56–60. Yeung, L.W.Y., So, M.K., Jiang, G., Taniyasu, S., Yamashita, N., Song, M., Wu, Y., Li, J., Giesy, J.P., Guruge, K.S., Lam, P.K.S., 2006. Perfluorooctanesulfonate and related fluorochemicals in human blood samples from China. Environ. Sci. Technol. 40, 715–720.
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Background levels of Persistent Organic Pollutants in humans from Taiwan: Perfluorooctane sulfonate and perfluorooctanoic acid Jen-Yi Hsu a, Jing-Fang Hsu b, Hsin-Hui Ho a, Chow-Feng Chiang c, Pao-Chi Liao a,⇑ a
Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, 138 Sheng-Li Road, Tainan 704, Taiwan L5 Research Center, China Medical University Hospital Taichung, 138 Sheng-Li Road, Tainan 704, Taiwan c Department of Public Health, China Medical University, 138 Sheng-Li Road, Tainan 704, Taiwan Taiwan b
h i g h l i g h t s To determine the background levels of PFOS and PFOA in the Taiwanese population. Investigate the age-, gender-factors that are potentially related. To compare with various countries. We report the PFOS and PFOA levels of serum samples in the general population of Taiwan. The concentrations of PFOS and PFOA in Taiwanese serum samples were no higher than those from other countries.
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Article history: Received 18 November 2012 Received in revised form 8 June 2013 Accepted 16 June 2013 Available online 22 July 2013 Keywords: Perfluorinated compounds Perfluorooctane sulfonate (PFOS) Perfluorooctanoic acid (PFOA) Human serum Taiwan Background
a b s t r a c t Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have recently received attention due to their widespread contamination of the environment. PFOS and PFOA are stable in the environment and resistant to metabolism, hydrolysis, photolysis and biodegradation. PFOS and PFOA have been found in human blood and tissue samples from both occupationally exposed workers and the general worldwide population. This study aimed to determine the background levels of PFOS and PFOA in the Taiwanese population, investigate related factors, and compare exposure in Taiwan to that in other countries. The concentration of PFOS in the 59 serum samples collected from the general population in Taiwan ranged from 3.45 to 25.65 ng mL1 (median: 8.52), and the concentration of PFOA ranged from 1.55 to 7.69 ng mL1 (median: 3.22). There was a significant positive correlation (r = 0.51; p < 0.0001) between PFOS and PFOA concentrations. Males had higher concentrations of PFOA and PFOS than females. PFOS levels in serum increased with age. This study is the first investigation to reveal the PFOS and PFOA levels of serum samples in the general population of Taiwan. The levels of PFOS and PFOA in Taiwanese serum samples were comparable with those from other countries (PFOS: 5.0–35 ng mL1, PFOA: 1.5– 10 ng mL1). Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction Perfluorinated compounds (PFCs) are persistent environment pollutants. Due to their widespread use in manufacturing Polyvinyl chloride (PVCs) and consumer products, PFCs are common in the environment and in biota (Giesy and Kannan, 2001; Prevedouros et al., 2005; Houde et al., 2006). They have been used to manufacture popular consumer products such as nonstick and stain-resistant coatings of cookware, food containers, breathable waterproof textiles, furniture, food packing materials, and carpets
⇑ Corresponding author. Address: Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, 138 Sheng-Li Road, Tainan 704, Taiwan. Tel.: +886 6 2353535x5566; fax: +886 6 2752484. E-mail address: [email protected] (P.-C. Liao). 0045-6535/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.chemosphere.2013.06.047
(Butenhoff et al., 2006; Lau et al., 2007; US EPA, 2010). Previous research on PFCs has focused on perfluorocarboxylates (PFCAs) and perfluorosulfonates (PFSAs) (Rhoads et al., 2008; Plumlee et al., 2009; Butt et al., 2010; Lee et al., 2010; Wang et al., 2011). PFCAs and PFSAs are of particular concern because of their toxic effects, persistence in the environment, and potential for bioaccumulation (Fromme et al., 2009). The two most common PFCs found in the environment, PFOS and PFOA, contain an eight-carbon backbone. In humans, the average half-life for elimination of PFOS has been estimated at 5.4 years; PFOA’s half-life is estimated at 3.8 years (Olsen et al., 2007a). Toxicity studies in animals have demonstrated adverse health effects from PFC exposure, such as reduced body weight, hepatotoxicity, developmental toxicity, immunotoxicity and hormonal effects (Lau et al., 2007). In 2006, the US Environmental Protection
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Agency (EPA) launched the PFOA Stewardship Program. The participating companies pledged to reduce emissions and product content of PFOA, PFOA precursors and related higher homolog chemicals by 95% by 2010 and to work toward eliminating emissions and the product content of these PFCs by 2015 (US EPA, 2001). While certain PFCs, including PFOS and PFOA, are being voluntarily phased out by industry, they may still be present in older products. The primary sources of human exposure to PFOS and PFOA include drinking water, food packaging, breast milk, household dust, and chemicals in the workplace (Lau et al., 2007; D’Hollander et al., 2010; Goosey and Harrad, 2011; Kim et al., 2011). Due to its persistence and bio-accumulative properties, PFOS was added to the Stockholm Convention on Persistent Organic Pollutants in 2009 (Geneva:Stockholm Convention Secretariat, 2009). Levels of PFOS and PFOA in samples of human blood vary widely among countries. A comprehensive overview of exposure to PFCs in the general populations of different countries has been published (Fromme et al., 2009). Most data that are relevant to human exposure to PFCs are reported for relatively industrialized countries. The levels of PFOS are higher in North Americans than those in European, Asian, and Australian populations (Hemat et al., 2010). For Taiwan, levels of perfluorinated chemicals in umbilical cord blood and in a cohort of young people in a hypertension study have been reported (Lien et al., 2011; Lin et al., 2011). However, the background levels of PFOS and PFOA in the Taiwanese general population have not been investigated. The present study was designed to determine the background levels of PFOS and PFOA in the Taiwanese population and to investigate related factors.
2. Materials and methods 2.1. Study population and sample collection All of the study subjects were volunteers living in the Taichung, Taiwan. Recruitment information posted by: (1) distribute the flyers, (2) using the internet to disseminate information and (3) newspaper advertisement. Subjects were selected for this investigation according to the following criteria: (1) they had resided in the sampling area for at least the previous five years; (2) they had not been exposed to readily identifiable point sources of PFOS and PFOA, such as in the workplace; (3) they were over 18 years and under 60 years of age; and (4) they were not known to be pregnant or have illnesses or heart conditions that could increase the risks associated with having blood taken. One hundred twenty subjects from the general population were recruited in Taichung, Taiwan; subjects came from eight urban areas (Central Dist, East Dist, South Dist, West Dist, North Dist, Beitun Dist, Xitun Dist and Nantun Dist). Taichung (literally mean in Chinese is ‘‘Central Taiwan’’) is a city located in western Taiwan, with a population of just over 2.6 million people (11.5% of Taiwan), making it the third largest city on the island. Taichung’s location and population structure indicates that it provides a fair representation of the wider Taiwanese population. Matched by number, men and women were randomly sampled from each area. But, one female subject abstained from participating in this study. Finally, 59 subjects from the general population were recruited in Taichung, Taiwan, in May 2011. Among 59 subjects, 30 were males (51%) and 29 were females (49%). The average age of the 59 subjects was 41.3 ± 13.1 years (mean ± standard deviation) and ranged from 19.8 to 65.0 years. Blood samples were drawn by professional nurses and taken using chemically clean VACUETTEÒ Blood Tubes (Greiner Bio-One Inc., Austria) containing no anti-coagulants. The coagulated blood was then centrifuged to obtain serum samples, which were kept frozen at 80 °C until analysis. All samples were anonymous but
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were accompanied by data concerning the gender, age and location of residence of the donors. Informed consent was obtained from the subjects, and the study protocol was approved by the medical ethics committee of the National Cheng Kung University Hospital, Tainan, Taiwan. 2.2. Chemicals and reagents Perfluorooctanoic acid (PFOA; purity > 96%), perfluorooctyl sulfonate (PFOS; purity > 98%), and ammonium acetate were purchased from Sigma–Aldrich (St. Louis, MO, USA). The internal standard 13C4-perfluorooctanoic acid (13C4-PFOA) was purchased from Wellington Laboratories (Guelph, Ontario, Canada). Milli-Q water was obtained from a Millipore water purification system (Billeria, MA, USA). Ammonium acetate (purity: N 99% by HPLC) was purchased from Aldrich (Steinheim, Germany). Acetonitrile was LC/MS grade from Sigma–Aldrich (St. Louis, MO, USA). Methanol was LC/MS grade from J.T. Baker (Phillipsburg, NJ, USA). Disodium hydrogen phosphate was purchased from Wako Pure Chemicals (Osaka, Japan). Solid-phase extraction was performed with Octadecyl (C18) cartridges (500 mg/6 mL) from J.T. Baker. Fetal bovine serum was purchased from Thermo Scientific HyClone (South Logan, UT, USA). 2.3. Preparation of serum samples Serum samples were subjected to a clean-up procedure using the dispersive carbon method described by (Vassiliadou et al., 2010). One half milliliter of blood serum was promptly pipetted into a 15-mL polypropylene centrifuge tube, and then 100 lL of the internal standard working solution (containing 10 ng mL 1 13 C4-labeled PFOA in methanol) was added. Five milliliters of acetonitrile was added, and the sample was vortex-mixed for 1 min. Finally, the sample was centrifuged at approximately 8500g for 15 min to clarify the supernatant. The organic phase was evaporated until dry in a flash evaporator, and the residue obtained was dissolved in 5 mL of phosphate buffer solution (PB) 0.05 M, pH = 7.8. Solid-phase extraction was performed as follows. After conditioning a C18 cartridge with 2 mL of methanol and 5 mL of water, the residue dissolved in phosphate buffer was passed through the cartridge. The cartridge was then washed with 5 mL of water, and PFOS and PFOA were eluted from the cartridge with 5 mL of methanol. The flow rate of the cartridge was approximately 1–2 drops per second. The organic phase was evaporated until dry in a flash evaporator. The dry residue was then dissolved in 200 lL of the HPLC mobile phase (MeOH – 5 mM ammonium acetate (20:80, v/v). 2.4. PFOS and PFOA analysis All sample extracts were analyzed by liquid chromatography– tandem mass spectrometry (LC–MS/MS) with electrospray ionization (ESI) operating in negative mode. The extracts (20 lL injection volume) were chromatographed on a ZORBAX Eclipse XDB-C18 column (3.5 lm, 50 mm 2.1 mm i.d., Angilent) using Angilent 1200 HPLC. The mobile phase was A: 2.0 mM ammonium acetate in water and B: methanol. The solvent gradient started at 60% A and 40% B (flow rate of 0.25 mL min1) and then increased to 75% B by 0.5 min, and then increased to 100% B by 5 min, held for 2.5 min, and then down to 30% B by 0.1 min, held for 1.9 min. The HPLC was interfaced to a triple quadrupole API 5000 (Applied Biosystems) equipped with a TURBO VTM ion source operating in negative ion mode. The source temperature was maintained at 300 °C and the spray voltage at 4500 V. The analyses were performed with a multiple reaction monitoring (MRM) method that monitored two mass transitions (parent ion/product ion) for each analyte.
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PFOS : 499 ! 99; PFOA : 413 ! 369; 13
499 ! 130 413 ! 169
C4 PFOA : 417 ! 372
The values of the voltages applied to the tube lense offset and the collision cell were optimized by direct infusion of a solution containing the analytes. Confirmation of analyte identity was based on retention time and on the relative response of the secondary mass transition to the primary mass transition. 2.5. Quantification and quality assurance Quantification was performed using the isotope-labeled internal standard method. To achieve lower detection limits and minimize background signal due to contamination, all accessible polytetraflurethylene (PTFE) materials were removed from the instruments and apparatus. The containers were extracted with methanol and analyzed for PFOS and PFOA. No contamination of PFOS and PFOA was found above the limit of quantification (LOQ) in containers, solution or chemical regents used in the analysis. One blank sample (Milli-Q water) was extracted with each batch of 15 samples to check for possible laboratory contamination and interference. The syringes and filters used in sample preparation were all washed by methanol before analyzing the sample. The LOQ were determined as signal/noise (S/N) ratio of 10. More specifically, LOQ was calculated at 0.25 ng mL1 for both PFOS and PFOA. The cattle serum samples were spiked with 4 ng mL1 of target standards to evaluate the recovery. The extraction recovery ranges of PFOS and PFOA were 73.9–106% and 100–121%, respectively.
Fig. 1. Correlation between the PFOS and PFOA concentrations, r = 0.51, p < 0.001, N = 59.
2.6. Statistics The Shapiro–Wilk normality test was used to determine whether a random sample of the levels of PFOS and PFOA examined in this study followed a normal distribution. Nonparametric Mann–Whitney U test was used to compare the serum levels of PFOS and PFOA according to gender. Differences for which p < 0.05 were considered to be statistically significant. The associations between age, gender, and concentration were evaluated by the Spearman correlation, a linear regression model. The statistical analysis was performed using the Statistica (version 6.0, StatSoft Inc., Tulsa, OK) software system.
Fig. 2. Difference between PFOS and PFOA concentrations.
3. Results PFOS and PFOA were quantified in 59 samples, all samples contained PFOS and PFOA at concentrations above the LOQ. The descriptive statistics for PFOS and PFOA are presented in Table 1. There was a strong correlation between PFOS and PFOA concentrations (Spearman r = 0.51, p < 0.0001) (Fig. 1). In general, PFOS concentrations of most samples were higher than PFOA concentrations; in only one sample was the PFOA concentration
Table 1 Serum concentrations (ng mL1) of PFOS and PFOA in Taiwanese. Male (n = 30)
Female (n = 29)
Total (n = 59) Fig. 3. Concentrations (ng mL1) of PFOS and PFOA by gender.
PFOS Range Median GM(SD)
4.67–22.61 10.23 10.64(5.10)
3.45–25.65 6.01 7.12(5.61)
3.45–25.65 8.52 8.96(5.67)
PFOA Range Median GM(SD)
2.07–7.69 3.77 3.83(1.24)
1.55–5.98 2.48 2.77(1.21)
1.55–7.69 3.22 3.27(1.32)
GM: geometric mean (ng ml1) and SD: standard deviation.
slightly higher than that of PFOS. The difference between PFOS and PFOA concentrations is shown in Fig. 2. The median of PFOS and PFOA concentrations were significantly higher (p < 0.05) in males than in females (Fig. 3). PFOS levels in serum increased with age (r = 0.39; p < 0.01), but the same phenomenon was not found for PFOA (r = 0.18; p = 0.184) (Fig. 4).
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(7.39 ng mL1 and 1.35 ng mL1) (Chan et al., 2011). The PFOS and PFOA serum concentrations in other countries are shown in Fig. 5. The levels of PFOS and PFOA in Taiwanese serum samples were comparable with those from other countries (PFOS: 5.0– 35 ng mL1, PFOA: 1.5–10 ng mL1). The uses of PFOS and PFOA are different. In the semiconductor industry, PFOS is used in multiple photolithographic chemicals including: photoacid generators (PAGs) and anti-reflective coatings (ARCs). The dominant use of PFOA is as an emulsifier for the emulsion polymerization of fluoropolymers such as polytetrafluoroethylene (PTFE or Teflon) (Lau et al., 2007). Because of their different uses, their exposure pathways are also different. In this report there was a strong correlation between PFOS and PFOA concentrations (Spearman r = 0.51, p < 0.0001) (Fig. 1). It is possibly exposure from food, drinking water or dust (Haug et al., 2011). Because PFOS and PFOA can remain in the animal and environment. The half-life of PFOS is longer than PFOA, the concentration levels of PFOS was higher than PFOA in the subjects. In Fig. 2, it was shown that the concentration levels of PFOS was higher than PFOA in the 58 people of the subjects.
4.2. Gender
Fig. 4. (A) Relationships between subject age and PFOS concentrations (N = 59, r = 0.39, p < 0.01). (B) Relationships between subject age and PFOA concentrations (N = 59, r = 0.18, p = 0.1841).
4. Discussion 4.1. Background levels of PFOS and PFOA in the Taiwanese population This study evaluated the background levels of PFOS and PFOA in 59 samples from individual volunteers in Taiwan and provides important documentation of the distribution of PFOS and PFOA levels in the general population. The data can be used to (1) evaluate the degree of PFOS and PFOA exposure in individual subjects or (2) identify subjects with an elevated exposure to PFOS and PFOA relative to background levels. The median value of PFOS (8.52 ng mL1) was higher than that of PFOA (3.22 ng mL1). This result is similar to previous biological monitoring investigations of PFOS and PFOA levels in general population groups from other countries. In the United States, there have been several reports on PFOS and PFOA concentrations in unpooled and pooled human serum samples, including those from Red Cross blood donors (Olsen et al., 2003a,b, 2005; Calafat et al., 2007; Olsen et al., 2007b, 2008). The means were generally around 5–25 ng mL1 for PFOS and 2–10 ng mL1 for PFOA. The mean concentrations of PFOS and PFOA in human serum have also been examined in Japan (6.19 ng mL1 and 4.10 ng mL1) (Harada et al., 2010), China (6.67 ng mL1 and 2.32 ng mL1) (Guo et al., 2011), Spain (7.6 ng mL1 and 1.65 ng mL1) (Ericson et al., 2007), Greece (10 ng mL1 and 2 ng mL1) (Vassiliadou et al., 2010), Australia (15.2 ng mL1 and 6.4 ng mL1) (Toms et al., 2009), Greenland (24.6 ng mL1 and 5.2 ng mL1) (Bonefeld-Jorgensen et al., 2011), German females (15 ng mL1 and 10 ng mL1), German males (25 ng mL1 and 10 ng mL1) (Wilhelm et al., 2009) and Canada
Males and females had significantly different serum concentrations of PFOA and PFOS. The levels of PFOS and PFOA in males were higher than those in females. In earlier studies, gender differences of PFOS and PFOA concentration were also found in the general population from Japan (Harada et al., 2004) and Australia (Toms et al., 2009). However, a study in Spain reported no statistically significant difference in PFOS levels between the males and females of the serum pools (Ericson et al., 2007). Females eliminate PFOA in the urine more rapidly than males; this is largely due to active renal excretion. Several studies have investigated the cause of this sex difference in elimination of PFOA in rats. Administration of probenecid (an inhibitor of the renal active secretion system for organic acids) reduced the elimination of PFOA in female rats. The elimination of PFOA in male rat is virtually unaffected by probenecid administration. Therefore, the female rat possesses an active secretory mechanism which rapidly eliminates PFOA from the body (Hanhijärvi et al., 1982). In male rats, testosterone has been shown to exert an inhibitory effect on renal excretion of PFOA (Vanden Heuvel et al., 1992). Castration of male rats increased the elimination of PFOA in the urine. This is a male specific response, as ovariectomised female rats with or without testosterone treatment had the same urinary PFOA excretion as intact females (Committee on Toxicity of Chemicals in Food Consumer Products and the Environment, 2005). Similar gender differences were reported in rats exposed to PFOA: the half-lives were longer in males than females (Kudo and Kawashima, 2003).
4.3. Age In this study, we found that concentrations of PFOS increased significantly with age, but not those of PFOA. Previous studies have reported the similar finding that PFOS concentrations in older adults were significantly higher than younger adults (Kärrman et al., 2006; Nilsson et al., 2010), but the results are not uniform throughout the literature. Researchers found an age effect for PFOA and PFOS in German females, but the same phenomenon was not found in German males (Fromme et al., 2007). There were no age differences in the concentrations of PFOA and PFOS in a Chinese population (Yeung et al., 2006). Elucidation of the effects of age on PFOS accumulation, metabolism and excretion in humans is complicated by individual variations in lifestyle.
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Fig. 5. Concentrations of PFOS and PFOA in blood samples of people from various countries (Olsen et al., 2003a; Olsen et al., 2003b; Olsen et al., 2005; Calafat et al., 2007; Ericson et al., 2007; Olsen et al., 2007; Olsen et al., 2008; Toms et al., 2009; Wilhelm et al., 2009; Harada et al., 2010; Vassiliadou et al., 2010; Bonefeld-Jorgensen et al., 2011; Chan et al., 2011; Guo et al., 2011).
5. Conclusion This study is the first investigation to document the PFOS and PFOA levels of serum samples in the general population of Taiwan. The background exposure data of the Taiwanese population can provide a scientific basis for setting up PFOS and PFOA monitoring and regulatory programs. Since all samples analyzed in the present study were acquired during 2011, it was not possible to investigate the temporal trend of PFOS and PFOA in Taiwan. This issue could be the subject of a future study and scheduled epidemiologic research in the area of perfluoroalkyls and human developmental outcomes. A significant positive correlation between PFOS and PFOA serum concentrations was observed in the present study (r = 0.49; p < 0.0001). The serum concentrations of PFOS and PFOA were significantly higher in males than in females. Higher levels of PFOS in serum samples were associated with age. Although the sampling years and the mean age of the other countries were different. The concentrations of PFOS (median: 8.52 ng mL1) and PFOA (median: 3.22 ng mL1) in Taiwanese serum samples were no higher than those from other countries (PFOS: 5.0–35 ng mL1, PFOA: 1.5–10 ng mL1). Acknowledgment This work was supported by Grants (NSC100-2113-M-006-002MY3) from the National Science Council of Taiwan. References Bonefeld-Jorgensen, E.C., Long, M., Bossi, R., Ayotte, P., Asmund, G., Kruger, T., Ghisari, M., Mulvad, G., Kern, P., Nzulumiki, P., Dewailly, E., 2011. Perfluorinated compounds are related to breast cancer risk in Greenlandic Inuit: a case control study. Environ. Health 10. Butenhoff, J.L., Olsen, G.W., Pfahles-Hutchens, A., 2006. The applicability of biomonitoring data for perfluorooctanesulfonate to the environmental public health continuum. Environ. Health Perspect. 114, 1776–1782. Butt, C.M., Muir, D.C.G., Mabury, S.A., 2010. Elucidating the pathways of poly- and perfluorinated acid formation in rainbow trout. Environ. Sci. Technol. 44, 4973– 4980. Calafat, A.M., Wong, L.-Y., Kuklenyik, Z., Reidy, J.A., Needham, L.L., 2007. Polyfluoroalkyl chemicals in the US population: data from the National Health and Nutrition Examination Survey (NHANES) 2003–2004 and comparisons with NHANES 1999–2000. Environ. Health Perspect. 115. Chan, E., Burstyn, I., Cherry, N., Bamforth, F., Martin, J.W., 2011. Perfluorinated acids and hypothyroxinemia in pregnant women. Environ. Res. 111, 559–564.
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