ASSESSMENT OF HEALTH RISKS AND HUMAN EXPOSURE ASSOCIATED WITH PERFLUORINATED COMPOUNDS (PFCs) IN TAP WATER FROM CHINA AND OTHER COUNTRIES MAK YIM LING MASTER OF PHILOSOPHY CITY UNIVERSITY OF HONG KONG AUGUST 2009
CITY UNIVERSITY OF HONG KONG 香港城市大學 Assessment of health risks and human exposure associated with perfluorinated compounds (PFCs) in tap water from China and other countries 全氟化合物在中國及其他國家自來水所引致的健康風險及其對人體暴露量的評估 Submitted to Department of Biology and Chemistry 生物及化學系 in Partial Fulfillment of the Requirements for the Degree of Master of Philosophy 哲學碩士學位 by Mak Yim Ling 麥艷玲 August 2009 二零零九年八月
Abstract Perfluorinated compounds (PFCs) are a group of emerging pollutants that have received considerable attention recently. Besides the two well-known PFCs, perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), other perfluorinated acids, including short-chain (< eight carbons) or long-chain ( eight carbons) sulfonates or carboxylates, have been found in aqueous environment over the world. PFOS and PFOA have been detected not only in raw waters, but also in treated drinking water from Germany, Italy, Spain, Poland, Japan, Malaysia, Thailand, Vietnam and Canada. Because of the low removal efficiency of PFCs by conventional drinking water purification processes like coagulation, sedimentation and chlorination, other PFCs may also be present in purified water, resulting in human exposure. Even though these PFCs usually occur at ppt levels, contamination of PFCs in drinking water has nevertheless prompted concern in both developed and developing countries, as water consumption occurs daily over the course of a lifetime and PFCs are bioaccumulative and have half-lives up to several years, resulting in chronic exposure to these compounds. Recent development of a sensitive and accurate analytical method for trace analysis of 20 PFCs, including several short- and long-chain compounds and their precursors, enabled their quantification in tap water samples collected from 2006 2008 in China, Japan, India, USA and Canada. The target analytes of the present study included eight perfluoroalkyl sulfonates (PFASs) and twelve perfluoroalkyl carboxylates (PFCAs), which were separated, identified and quantified by employing solid phase extraction (SPE) together i
with high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). Of the measured PFCs, sixteen were present at detectable concentrations in tap water samples: PFOS, perfluorohexane sulfonate (PFHxS), perfluorobutane sulfonate (PFBS), perfluoropropane sulfonate (PFPrS), perfluoroethane sulfonate (PFEtS), perfluorooctane sulfonamide (PFOSA), N-ethyl perfluorooctane sulfonamidoacetate (N-EtFOSAA), perfluorododecanoic acid (PFDoDA), perfluoroundecanoic acid (PFUnDA), perfluorodecanoic acid (PFDA), perfluorononanoate (PFNA), PFOA, perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), and perfluorobutanoic acid (PFBA). Tap water from Japan contained the highest number of detectable PFCs (sixteen PFCs), whereas only seven PFCs samples were detected in samples collected from India. PFOS and PFOA were the two most frequently detected PFCs, and were quantified in more than 80% of the tap water samples from China, Japan, USA and Canada. However, these two compounds occurred in less than 40% of the Indian tap water samples. Tap water from Shanghai (China) contained the highest concentration of total PFCs (mean = 130 ng/l), whereas samples from Toyama (Japan) contained only 0.612 ng/l of total PFCs. Although waters from India usually contained relatively low concentrations of PFCs, high level of PFHxS was measured in tap water from Chennai (n = 1), indicating the presence of specific source(s) of PFCs influencing the quality of Indian tap water. Distinct PFC composition profiles in the tap water samples from the various countries were observed, likely because of variation in the production and usage of PFCs ii
in these countries. Other than PFOS and PFOA, short chain PFCs like PFHxS, PFBS, PFPeA and PFBA were prevalent in tap water samples, reflecting the importance of identifying short-chain PFCs in tap water. Comparison of PFC concentrations with provisional health advisory, health-based values (HBVs) and advisory guidelines derived for PFOS, PFOA, PFBA, PFHxS, PFBS, PFHxA and PFPeA by the U.S. EPA and Minnesota Department of Health (USA) showed that the corresponding maximum measured concentrations of these compounds in tap water from China, Japan, India, USA and Canada were all below these guideline values. Risk quotients (RQs) of PFOS, PFOA, PFBA, PFHxS, PFBS, PFHxA and PFPeA due to consumption of these tap water samples were less than unity, showing that there may be no immediate risk posed to consumers by PFCs. Based on a simplified one-compartment toxicokinetic model in which it was assumed that PFCs were totally absorbed from the intestine, the estimated serum PFOS and PFOA levels in were calculated for consumption of Chinese tap water and compared with measured serum concentrations of PFCs in Chinese human blood samples reported by previous studies. The results indicated that drinking PFC-contaminated tap water contributed less than 1% of the serum PFOS concentrations in human blood from several Chinese cities, with the exception of those from Nanjing, where 8.2% of serum PFOS concentrations was found to be due to drinking water. However, tap water may be a relatively significant exposure pathway of Chinese citizens to PFOA, as at least 13% of PFOA in serum could be attributed to drinking tap water. iii
Boiling tap water before consumption is a common practice in China which may alter PFC concentrations and composition profiles in tap water. Boiling water with a mixture of 17 native PFC standards and 4 mass-labeled PFC standards for 15 minutes was shown to cause a significant reduction in the concentrations of volatile PFCs such as PFOSA and N-EtFOSAA, but the levels of perfluorinated acids were not significantly different after boiling. Drinking boiled water, in turn, leaded to a change in PFC as this treatment may help to minimize the exposure to volatile PFCs, although the exposure of the non-volatile perfluorinated acid still occurred via the water consumption. To conclude, PFCs have been identified and quantified in tap water from China, Japan, India, USA and Canada, reflecting that PFC contamination in tap water is a global issue. Risks associated to PFOS, PFOA, PFBA, PFHxS, PFBS, PFHxA and PFPeA in tap water from these countries were low, but further studies should be carried out so as to characterize the risks posed by PFC mixtures. Drinking PFC-contaminated tap water may be a relatively important PFOA exposure pathway to Chinese and researches related to the toxicokinetic of other PFCs should be performed in order to provide more information for the estimation of contribution of drinking water to human PFC exposure. iv
List of figures Title Page Figure 1.1 The chemical structures of some well-known PFCs 2 Figure 1.2 Estimated total global POSF production volume (1970-2002). 6 Estimates of total global (green line) and 3M s production (purple line) are compared to estimates from Smithwick et al. (2006) (red line) and Prevedouros et al. (2006) (blue line). (Note: Smithwick et al. (2006) and Prevedouros et al. (2006) assume that POSF production stops with 3M) (Source: Paul et al., 2009). Figure 1.3 A schematic diagram of PFC treated carpets providing oil and 15 water resistance Figure 1.4 A schematic diagram of the transports of PFCs from the sources to 19 the environment Figure 2.1 Sampling locations of tap water from China, Japan, India, USA and 43 Canada Figure 2.2 LC-MS/MS chromatographs of individual PFC standards (1 ppb 50-53 each); PFPrS, PFEtS, PFPeA and PFBA were identified using a RSpak JJ-50 2D column, and the other PFCs were identified using Keystone Betasil C18 column Figure 3.1 Frequency of detection (%) of individual PFCs in Chinese tap 62 water Figure 3.2 Mean concentrations (ng/l) of total PFASs and PFCAs in Chinese 63 tap water Figure 3.3 Means of concentrations (ng/l) and standard deviations of total 67 PFCs, PFASs and PFCAs in tap water from different Chinese cities Figure 3.4 Concentrations (ng/l) of PFCs in tap water samples from China 68 (No bar: < corresponding LOQs, i.e. 0.0040 1.6 ng/l) Figure 3.5 Composition profiles of PFCs in (a) tap water samples from 71 different Chinese cities and (b) river water from Dongjiang and Yangtze Rivers (So et al., 2007) (Note: PFPrS, PFEtS, PFPeA and PFBA were not analyzed in Chinese river water) Figure 3.6 Frequency of detection (%) of individual PFC in tap water from (a) 74-75 Japan, (b) India, (c) USA and (d) Canada Figure 3.7 Means of concentrations (ng/l) and standard deviations of total 80 PFCs, PFASs and PFCAs in tap water from Japan, India, USA and Canada Figure 3.8 Concentrations (ng/l) of PFCs in tap water samples from Japan, 81 India, USA and Canada (No bar: < corresponding LOQs, i.e. 0.0040 1.6 ng/l) Figure 3.5 Composition profiles of PFCs in tap water samples from Japan, 84 India, USA and Canada Figure 3.10 Global comparisons of PFOS and PFOA levels (ng/l) in tap/drinking water 88 ix
List of figures Figure 4.1 Figure 4.2 Figure 4.3 Figure 4.4 Figure 4.5 Figure 4.6 Figure 4.7 Figure 4.8 Figure 5.1 Figure 5.2 Figure 5.3 Summary of risk quotients (RQs) of individual PFCs, including PFOS, PFHxS, PFBS, PFOA, PFHxA, PFPeA and PFBA in tap water (sample size >1; Provisional Health Advisory: PFOS = 200 ng/l,and PFOA = 400 ng/l; HBV: PFBA = 600 ng/l; advisory guideline for PFHxS = 600 ng/l, PFBS = 600 ng/l, PFHxA = 1000 ng/l and PFPeA = 1000 ng/l [the U.S. EPA (2009); the Minnesota Department of Health (U.S.) (2007)] Cumulative plot of PFOS concentrations in Chinese tap water, together with the provisional health advisory of PFOS issued by the U.S. EPA (2009) Cumulative plot of PFOA concentrations in Chinese tap water, together with the provisional health advisory of PFOA issued by the U.S. EPA (2009) Cumulative plot of PFBA concentrations in Chinese tap water, together with the health-based value of PFOS issued by the Minnesota Department of Health (US) (2007) Cumulative plot of PFHxA concentrations in Chinese tap water, together with the advisory guideline of PFHxA issued by the Minnesota Department of Health (US) (2007) Cumulative plot of PFPeA concentrations in Chinese tap water, together with the advisory guideline of PFPeA issued by the Minnesota Department of Health (US) (2007) Cumulative plot of PFHxS concentrations in Chinese tap water, together with the health-based value of PFHxS issued by the Minnesota Department of Health (US) (2007) Cumulative plot of PFBS concentrations in Chinese tap water, together with the health-based value of PFBS issued by the Minnesota Department of Health (US) (2007) The experimental design for examining the effects of boiling on PFC concentrations in waters Relative concentrations of PFCs in boiled and non-boiled MilliQ water Relative concentrations of PFCs in Japanese boiled and non-boiled tap water 96 97 98 99 100 100 101 101 111 117 118 x
List of tables Title Page Table 1.1 Molecular formulas and molecular weights of PFCs 10 Table 1.2 Physical properties of PFOS and PFOA 11 Table 2.1 Detailed information on the sample locations 44 Table 2.2 Detailed information for Chinese tap water samples 45 Table 2.3 Detailed information for tap water from Japan, India, USA and 46 Canada Table 2.2 Detailed information for Chinese tap water samples 44 Table 2.4 Procedural blanks (ng/l), procedural recoveries (%) and matrix 56 spike recoveries (%) of PFCs Table 4.1 The guideline values of PFCs in drinking water, proposed by the 92 Minnesota Department of Health (US) and the U.S.EPA (2007, 2009) Table 4.2 The estimated daily intake (ng/day) of individual PFCs resulting 107 from drinking of Chinese tap water, assuming a person drink 2 L per day Table 4.3. Estimated serum PFOS and PFOA levels (ng/ml) in Chinese 108 people and contributions (%) to PFOS and PFOA human exposure due to drinking of tap water Table 5.1 Statistical analysis of PFCs in Milli-Q and Japanese tap waters with or without boiling 119 xi
Table of contents Abstract List of publication Paper published in conference proceedings Acknowledgements List of figures List of tables Table of contents Page no. i v vi vii ix xi Chapter 1 Chapter 2 Introduction 1.1 Perfluorinated compounds 1 1.1.1 Production of PFCs 3 1.1.2 Physiochemical properties of PFCs 7 1.1.3 Usage of PFCs 14 1.1.4 Sources of PFCs 17 1.1.5 Transport pathways 21 1.1.6 Detection of PFCs in environment 23 1.1.6.1 Air 23 1.1.6.2 Water 24 1.1.6.3 Sediment 24 1.1.6.4 Biota 25 1.1.7 Toxicity 27 1.2 Environmental conditions in China 30 1.2.1 Background 30 1.2.2 PFC levels in Chinese environment 31 1.2.3 PFC levels in biota from China 31 1.2.4 PFC levels in Chinese population 32 1.3 Exposure pathways of PFCs to the general population in 34 China 1.3.1 Consumption of contaminated food 34 1.3.2 Inhalation of PFC-contaminated air and dust 35 1.3.3 Drinking of PFC-contaminated water 36 1.4 Project objectives 39 Materials and methods 2.1 Standards and reagents 41 2.2 Sample collection 42 2.3 PFC extraction and clean up 47 2.4 Instrumental analysis and quantification 48 2.5 Quality control and quality assurance 54 2.6 Risk assessment 58 2.7 Estimation of serum PFC levels via drinking of tap 59 water and their contribution to PFC exposure to Chinese xii
Chapter 3 Chapter 4 Chapter 5 Perfluorinated compounds in tap water 3.1 PFC contamination in tap water from China 61 3.1.1 PFC concentration in tap water from different 64 Chinese cities 3.1.2 Composition profiles of PFCs in tap water from different Chinese cities 69 3.2 PFC contamination in tap water from Japan, India, USA 72 and Canada 3.2.1 PFC concentration in tap water from Japan, 76 India, USA and Canada 3.2.2 Composition profiles of PFCs in tap water from Japan, India, USA and Canada 82 3.3 Comparison of PFOS and PFOA levels in worldwide 85 drinking water Human health risk and contribution of contaminated tap water to human exposure 4.1 Background 89 4.2 Human health risk assessment of PFCs in tap water 89 4.2.1 Tap water from China 93 4.2.2 Tap water from other countries 94 4.2.3 PFC mixture in tap water 94 4.3 Estimation of average daily intake of PFCs, serum PFC 102 levels and contribution to PFC exposure via drinking of tap water to Chinese 4.3.1 Estimated daily intake of PFOS and PFOA via 103 drinking Chinese tap water 4.3.2 Estimated serum PFOS and PFOA levels in Chinese via drinking tap water and their contribution to human exposure 103 Effects of boiling on PFCs in tap water 5.1 Background 109 5.2 Methodology 110 5.2.1 Sample preparation 110 5.2.2 Chemical analysis 110 5.2.3 Data analysis 112 5.3 Changes in PFC levels in water upon boiling 112 5.3.1 Concentrations of PFCs in control groups (A1 112 and A-2) 5.3.2 Concentrations of PFCs in treatment groups (B- 1 and B-1) 113 Chapter 6 Concluding remarks 120 xiii
Chapter 7 References 124 Appendix 1 Appendix 2 Means of concentrations (ng/l) and standard deviations of PFCs in Chinese tap water Means of concentrations (ng/l) and standard deviations of PFCs in tap water from Japan, India, USA and Canada 146 148 xiv