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River water contaminated with perfluorinated compounds potentially posing the greatest risk to young children
Chemosphere 90 (2013) 1617–1624
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River water contaminated with perfluorinated compounds potentially posing the greatest risk to young children Dalaijamts Chimeddulam, Kuen-Yuh Wu ⇑ Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, No. 17, ShuJou Rd., Taipei 10055, Taiwan
h i g h l i g h t s " Young children are at the highest risk of exposure to PFCs via water consumption. " Residents reside near to Keya River are at highest risk of exposure to PFCs. " River water were used to surrogate as tapwater. " Deterministic and probabilistic risk assessment methods were used. " Probability density functions for exposure factors were plotted.
a r t i c l e
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Article history: Received 26 March 2012 Received in revised form 13 August 2012 Accepted 20 August 2012 Available online 27 September 2012 Keywords: Perflourinated compounds Exposure Risk assessment Water consumption Probabilistic analysis Hazard index
a b s t r a c t Although, humans are exposed to perflourinated compounds (PFCs) from various media, water consumption could be an important source for the residents living near to contaminated areas. Since comprehensive multimedia exposure model has not been developed for PFCs, assessment of the potential risk due to exposure to PFCs through direct water consumption could be a conservative estimate. The human health risks derived from the exposure to PFCs through water consumption were assessed for different age groups of general population in Taiwan using probabilistic approach. Based on available data on concentrations of PFCs in river water, exposure to PFOS, PFOA and PFDA via water consumption for different age groups were calculated using deterministic and probabilistic risk assessment methods. The oral non-cancer risks from PFOS, PFOA and their combination, expressed as a Hazard Index (HI), was determined by comparing oral exposure dose (through water intake) with the oral Reference Dose (RfD). The average exposure to PFOS, PFOA and PFDA via water consumption for adults ranged from 0.16 to 220.15, 0.43 to 12.5 and 0.43 to 2.36 ng kg-bw1 d1 and for children 0.13–354.3, 0.35–20.17 and 0.35–3.79 ng kg-bw1 d1, respectively. Probabilistic values of total HIs for all age groups reside near to Keya River exceed the RfD 2.4–4.8 times, corresponding mainly to PFOS with a percentage of 97%. In conclusions, children aged 1–3 years old and the residents reside near to Keya River are at the highest risk of exposure to PFCs via water consumption. Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction Perflourinated chemicals (PFCs) are all anthropogenic organic chemicals, which are used in a wide range of industrial and commerAbbreviations: CATT, C8 Assessment of Toxicity Team; CONTAM, The Scientific Panel on Contaminants in the Food Chain; EFSA, European Food Safety Authority; ELE/OPTO-A, electro/optoelectro A plants; EXPDs, exposure doses; HI, Hazard Index; HSP, Hsinchu Science Park; MDH, Minnesota Department of Health; PDFs, probability density functions; PFCs, perflourinated compounds (chemicals); PFDA, perflourodecanoic acid; PFOA, perflourooctanoic acid; PFOS, perflourooctane sulfonate; RfD, Reference Dose; SEM, semiconductor; TDI, Tolerable Daily Intake; USEPA, US Environmental Protection Agency; WHO, World Health Organization; WVDEP, West Virginia Department of Environmental Protection; WWTPs, waste water treatment plants. ⇑ Corresponding author. Tel.: +886 2 3366 8091; fax: +886 2 3366 8267. E-mail address: [email protected] (K.-Y. Wu). 0045-6535/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.chemosphere.2012.08.039
cial applications due to their persistence to biotic and abiotic degradation (OECD, 2002, 2005; Washburn et al., 2005; Fromme et al., 2009) and of significant health concern due to their adverse effects in animal toxicity and in human epidemiological studies such as, hepatotoxicity, developmental and reproductive toxicity, immunotoxicity, hormonal effects and carcinogenic potency (Thomford, 2001; OECD, 2002; 3M-Company, 2002; Seacat et al., 2002, 2003; Kennedy et al., 2004; Harada et al., 2005; USEPA, 2006; Lau et al., 2007; Andersen et al., 2008; Fei et al., 2008, 2009; Lin et al., 2009a, 2009b; Melzer et al., 2010; Lin et al., 2011; Wang et al., 2011; Bloom et al., 2010). PFCs spread globally in various environmental matrices, including air, surface water, sediments, aquatic invertebrates, fish, and other wildlife, predominanty in the aqueous environment (Martin et al., 2003). Several investigations suggested the discharge from industrial WWTPs as one of the significant point sources for
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PFCs pollution of the aquatic environment (Bossi et al., 2008; Lin et al., 2009c, 2010; Kim et al., 2012). As their environmental fate trend, PFCs have been revealed in drinking water in many countries in US, Europe and Asia Loos et al. (2007) exhibited PFOA and PFOS in tap water drawn from Lake Maggiore in Italy, which had similar concentrations to those in the lake. In some regions of China, concentrations PFOA and PFOS exceeded 10 ng L1, whereas the median concentrations were 4.2–5.4 ng L1 in rivers, which were comparable to those in the US, Europe and Japan (Saito et al., 2004; Jin et al., 2009). These investigations suggested that water treatment steps (sand filtration and chlorination) may not be efficient to remove the contamination of PFCs. (Skutlarek et al., 2006; Loos et al., 2007). Several extensive studies observed relatively high concentrations of PFCs in human serum (e.g. median 374 ng L1 of PFOA) among those, who used water from drinking water supply, which was highly contaminated by those compounds (e.g. 1900–18 600 ng L1 of PFOA) (U.S.EPA, 2001; LHWA, 2005; Skutlarek et al., 2006; Emmett et al., 2006; Loos et al., 2007). These data indicate that drinking water is the dominant source for the population resides near to contaminated areas. In recent years, some efforts utilizing activated carbon filtration, and more advanced water treatment processes succeeded for removals. Nevertheless, these successes are questionable in consistency over time (Bartell et al., 2009; Hölzer et al., 2009; Thompson et al., 2011). As their ubiquitous distribution, humans can be exposed to PFCs through not only drinking water, but also other pathways, including the ingestion with food, such as fish, seafood, livestock, crops and vegetables and house dust; inhalation with air; and water consumption, such as showering, and cleaning. As our current knowledge, few studies have been conducted in risk assessment for PFCs, mainly estimated potential exposure to PFOA and PFOS from various pathways predicting daily intakes deriving the Reference Doses and health based values from drinking water for general adult population in US and Europe (Paustenbach et al., 2007; Fromme et al., 2009). Given that the comprehensive multimedia exposure model has not been developed for human exposure to PFCs due to limited available data on different media, we aimed to maximize the estimates of the potential risk of exposure to PFCs through water consumption using probabilistic assessment. Semiconductor, electrochemical and optoelectronic industries have been grown rapidly in Taiwan. Recent studies reported higher level of PFCs in water area, including industrial and municipal WWTP effluents, rivers and coastal water in Taiwan with the predominant and prevalent exhibition of PFOA, PFOS, PFHxA and PFDA (upto 310, 5440, 406 and 58.2 ng L1, respectively) compared to those reported in other countries (Tseng et al., 2006; Lin et al., 2009c, 2010). The objective of the present study was to assess the human exposure to perflourinated compounds through water consumption for different age groups of general population in Taiwan using probabilistic approach. To the best of our knowledge, this is the first exposure assessment for PFDA through water consumption assessing the risk of all age groups, including children.
Fig. 1. Map of rivers of interest.
rivers located in northern Taiwan, which receive untreated municipal wastewater and agricultural wastewater directly from the cities and suburban area (Fig. 1) (Tseng et al., 2006). Second paper reported in 2009 by Lin et al. identified many different PFCs in river water from Keya, Touchien, and Xiaoli rivers located near to three major sources of potential PFC contamination (Lin et al., 2009c). The Keya River, serves as waste water drainage of semiconductor (SEM) fabrication plant, is greatly impacted by upstream industrial sources from Hsinchu Science Park (HSP). Correspondingly, The Touchien River, serves a population of 790 000, and the Xiaoli River, serves a population of 38 000, are impacted a half of its PFC load by upstream electronics/optoelectronics fabrication (ELE/OPTO) wastewaters and small optoelectronics factory, respectively (Fig. 1). PFOA, PFOS and PFDA were predominant and prevalent in all samples in both papers. Exposure point concentrations and probability density functions (PDFs) of PFOS, PFOA and PFDA in surface water, as an environmental compartment in the risk assessment are summarized in Table 1.
2. Materials and methods
2.2. Exposure assessment
2.1. Concentrations of PFCs in river water
Daily intakes of PFCs were calculated using both deterministic and probabilistic risk assessment methods for different age groups (<0.5; 0.5–0.9; 1–3; 4–12; 13–18; 19–64; >65). To evaluate the exposure doses for humans, PFC concentration values were converted into doses using U.S.EPA (1997) exposure equation, considering the concentration of contaminants in tapwater, the intake rate of tapwater, exposure frequency, exposure duration and body weight of an average individual (U.S.EPA, 1997). The equation is expressed as follows:
For the purposes of exposure assessment, PFC concentrations in the river water were used as surrogates for tapwater concentration. Results of two papers reported the concentrations of PFCs in water area in Taiwan, including industrial and WWTP effluents, rivers and coastal water, were adopted for exposure concentrations for water consumption. First investigation covered the surface water collected from the downstream of Tour-Chyan and Nan-Kan
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Exposure point concentration
SD
Probability density function
References
Distribution
95th Percentile
1.7 1.1 31 11.3 18.1
Lognormal Lognormal Lognormal Lognormal Lognormal
20.28 12.78 363.5 132.5 212.4
Lin (2009) Lin (2009) Lin (2009) Tseng et al. (2006) Tseng et al. (2006)
82 48.9 5440 4 79
8.2 4.9 544 0.4 7.9
Lognormal Lognormal Lognormal Lognormal Lognormal
96.14 57.33 6378 4.69 92.62
Lin (2009) Lin (2009) Lin (2009) Tseng et al. (2006) Tseng et al. (2006)
11 58.2 14.6 14 21
1.1 5.8 1.5 1.4 2.1
Lognormal Lognormal Lognormal Lognormal Lognormal
12.9 68.24 17.12 16.4 24.62
Lin (2009) Lin (2009) Lin (2009) Tseng et al. (2006) Tseng et al. (2006)
PFOA Xiaoli Touchien Keya Tour-Chyan Nan-Kan
17.3 10.9 310 113 181
PFOS Xiaoli Touchien Keya Tour-Chyan Nan-Kan PFDA Xiaoli Touchien Keya Tour-Chyan Nan-Kan
EXPD ¼ ðCW IRÞ=BW
ð1Þ 1
1
where EXPD is the exposure dose (ng kg-bw d ), CW is the concentration in water (ng L1), IR is the ingestion rate (L d1), and BW is the body weight (kg). 2.3. Exposure pathway and factor assumptions Exposure point estimates and probability density functions (PDFs) for exposure factors used to perform deterministic and probability risk assessments of theoretical human exposure to PFCs from consumption water are described in Table 2. Cwater – The concentrations of PFCs in water is supplied from the Tour-Chyan, Nan-Kan, Touchien, and Xiaoli rivers reported by Tseng et al. (2006) and Lin et al. (2009c). It is assumed that residents near to these rivers consume the river water as a sole source of potable water. The mean values and 95% upper confidence limit of the mean concentration were used as a conservative estimate of the mean concentration. IRtapwater – Water consumption was assumed 2.5 L d1 for Taiwanese adults based on data provided by Chen et al. (2003). Using logistic regression analysis on the U.S.EPA recommended tapwater intake for different age groups (in Tables 3–6 of Exposure factor
handbook, (U.S.EPA, 1997)), the average daily intake was adjusted for different age groups in Taiwan (Fig. 2). BW – Average body weight (kg). Average body weights for children aged under 5 years old were adopted from WHO growth standards (WHO, 2006) and others were adopted from the Nutrition and Health Survey in Taiwan (NAHSIT, 1993–1996; Tzeng et al., 1999). Data on body weight from both sources were available as a mean and standard deviation and sample size for every single age. In order to adjust data from above sources to the study, the initial data on body weight for single ages were combined into the different age groups of interest using the following equations:
Magegroup ¼
X
Ni Mi =
X
Ni
ð2Þ
where Magegroup is the mean body weight of an age group, Ni is sample size of i age, and Mi is the mean body weight of i age.
SD2agegroup ¼
X . X X ðNi 1ÞS2i þ ðMi DMÞ Ni 1
ð3Þ
where SDage group is standard deviation of body weight of an age group, Si is standard deviation of body weight of i age, and DM is the mean body weight of an age group.
Table 2 Point estimates and PDFs for exposure factors used to perform deterministic and probability risk assessments of theoretical human exposure to PFOA and PFOS from drinking water. Exposure parameter
Body weight (kg) <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65
Point estimate
SD
Probability density function
References
Distribution
50th Percentile
95th Percentile 8.28 9.8 15.81 49.69 75.34 82.43 80.95
5.21 9.01 12.56 30.11 54.91 64.79 61.2
1.66 0.47 1.85 10.53 11.38 10.01 11.1
Lognormal Lognormal Lognormal Lognormal Lognormal Lognormal Lognormal
4.96 9 12.43 28.42 53.77 64 60.22
Intake rate, drinking water (L d1) <0.5 0.27 0.5–0.9 0.29 1–3 0.8 4–12 1.5 13–18 1.8 19–64 2.5 <65 2.4
0.02 0.03 0.08 0.15 0.18 0.25 0.24
Lognormal Lognormal Lognormal Lognormal Lognormal Lognormal Lognormal
0.27 0.29 0.8 1.49 1.8 2.5 2.4
0.32 0.34 0.94 1.76 2.11 2.93 2.81
WHO (2006) WHO (2006) WHO (2006) NAHSIT (1993–1996) NAHSIT (1993–1996) NAHSIT (1993–1996) NAHSIT (1993–1996) Estimated from U.S.EPA Estimated from U.S.EPA Estimated from U.S.EPA Estimated from U.S.EPA Estimated from U.S.EPA Chen et al. (2003) Estimated from U.S.EPA
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Fig. 2. Logistic regressions of daily intake rate of drinking water for US population and adjusted for Taiwanese population.
2.4. Probabilistic analysis (exposure characterization and uncertainties) The daily intakes of PFOA and PFOS were studied through a probabilistic approach to avoid an underestimation of exposure and risks. A probabilistic analysis (Monte Carlo analysis) was performed to characterize variability and uncertainty in the exposure assumptions and to quantify the range of theoretical EXPDs associated with the exposure pathway (water consumption) for different age groups in accordance with U.S.EPA (1997) guidance. Probability density functions for each parameter were lognormally distributed. The mean point estimates were used to define the boundaries of input values randomly selected in Monte Carlo simulations. Monte Carlo simulations were run 50 000 times using Microsoft Excel™ 2007 and OracleÓ Crystal Ball, Fusion Edition, Release 11.1.1.3.00 software (Oracle Corporation, USA) and some graphs were plotted using SigmaPlot 11.0 software. Assumptions regarding PDFs and the distribution curves for different exposure factors were plotted and the percentile exposures (50th and 95th) for each compound were identified from the graphs. 2.5. Risk characterization Health risks derived from the exposure to PFCs through water consumption were assessed. The oral non-cancer risk, expressed as a Hazard Index (HI), was determined by comparing oral exposure dose (through water intake) with the oral Reference Dose (RfD) for each chemical using the following equation, and summed up HIs to assess total risk.
HI ¼ Exposure dose=RfD
deviation, median and 95th percentiles by all age groups for every river water. Average daily intake of all PFCs from water consumption shown in three tables is integrated in Fig. 3. The average adult exposure to PFOS, PFOA and PFDA via water consumption is ranged 0.16 ± 0.04–220.15 ± 51.14 ng kg-bw1 d1, 0.44 ± 0.1–12.5 ± 2.9 ng kg-bw1 d1, and 0.43 ± 0.1–2.36 ± 0.5 ng kg-bw1 d1, respectively. The average child exposure to PFOS, PFOA and PFDA via water consumption is ranged 0.13 ± 0.02–354.3 ± 72.87 ng kg-bw1 d1, 0.35 ± 0.05–20.17 ± 4.14 ng kg-bw1 d1, and 0.35 ± 0.05–3.79 ± 0.78 ng kg-bw1 d1, respectively. Children aged 1–3 years old are exposed to the highest level of all PFCs from all river water with the average daily intake of up to 0.35 lg kgbw1 d1 followed by infants aged less than 6 months with the average daily intake of up to 0.31 lg kg-bw1 d1. Due to large standard deviation (average daily intake of PFOS is 0.3 ± 0.12 lg kg-bw1 d1), children aged 4–12 years old have the highest intake rate of PFCs at 95th percentile (up to 0.52 lg kg-bw1 d1), while high intake rate for children aged 1–3 years old was up to 0.48 lg kg-bw1 d1. In this study, residents near to Keya River largely exposed to both PFOS and PFOA. Although, Keya River does not serve as water consumption, residents possibly will be exposed to these chemicals through dietary intake of fish and seafood taken from this river and through shower. Excluding this river, the second largest source for exposure to PFOS is the Xiaoli River, whereas the Nan-Kan River is the second largest source for PFOA. Residents reside near to the Touchien River are exposed to higher level of PFDA with the high intake rate up to 5.5 ng kg-bw1 d1 at 95th percentile compared to other two PFCs.
ð4Þ 3.1. Risk characterization
3. Results Deterministic and probabilistic results of environmental exposure to PFCs from water consumption for all age groups of Taiwan are summarized in Table 3. Table shows exposure point estimates of daily intake for each PFC and their probabilistic mean, standard
No risk criteria or standard health guidelines (benchmarks) were established by U.S.EPA. In 2002, the first oral benchmark dose for PFOA (C8) was determined by the C8 Assessment of Toxicity Team (CATT) at the West Virginia Department of Environmental Protection at 4.0 lg kg-bw1 d1 (WVDEP, 2002) (SI Table 1). The Health Risk Assessment Unit in the Minnesota Department of
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D. Chimeddulam, K.-Y. Wu / Chemosphere 90 (2013) 1617–1624 Table 3 Deterministic and probabilistic results of daily intake of PFCs from drinking water, ng kg-bw1 d1. Source of drinking water
PFOA Exposure point estimates
PFOS Probabilistic results Mean
SD
95th Percentile
Exposure point estimates
PFDA Probabilistic results Mean
SD
95th percentile
Exposure point estimates
Probabilistic results Mean
SD
95th percentile
Xiaoli River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65
0.90 0.56 1.10 0.86 0.57 0.67 0.68
0.99 0.56 1.13 0.97 0.59 0.68 0.7
0.34 0.08 0.23 0.37 0.15 0.14 0.16
1.63 0.71 1.54 1.65 0.86 0.94 1.0
4.25 2.64 5.22 4.09 2.69 3.16 3.22
4.68 2.65 5.34 4.60 2.81 3.24 3.32
1.64 0.40 1.09 1.76 0.71 0.68 0.77
7.74 3.36 7.29 7.89 4.10 4.46 4.70
0.57 0.35 0.70 0.55 0.36 0.42 0.43
0.63 0.35 0.72 0.61 0.38 0.43 0.45
0.22 0.05 0.15 0.24 0.09 0.09 0.1
1.04 0.45 0.98 1.05 0.55 0.6 0.63
Touchien River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65
0.56 0.35 0.69 0.54 0.36 0.42 0.43
0.62 0.35 0.71 0.61 0.37 0.43 0.44
0.22 0.05 0.15 0.23 0.09 0.09 0.10
1.03 0.45 0.97 1.05 0.55 0.59 0.63
2.53 1.57 3.11 2.44 1.60 1.89 1.92
2.79 1.58 3.18 2.74 1.67 1.93 1.98
0.98 0.24 0.66 1.05 0.43 0.40 0.46
4.62 2.0 4.35 4.69 2.45 2.66 2.81
3.02 1.87 3.71 2.90 1.91 2.25 2.28
3.33 1.88 3.79 3.24 1.99 2.3 2.36
1.17 0.29 0.78 1.24 0.5 0.48 0.55
5.49 2.38 5.17 5.55 2.90 3.17 3.35
16.07 9.98 19.75 15.44 10.16 11.96 12.16
17.69 10.0 20.17 17.31 10.59 12.25 12.5
6.19 1.51 4.14 6.6 2.69 2.58 2.9
29.24 12.63 27.5 29.67 15.46 16.85 17.83
281.92 175.09 346.50 271.01 178.33 209.91 213.33
310.86 175.75 354.30 305.01 186.36 214.82 220.15
109.37 26.59 72.87 116.59 47.30 45.05 51.14
514.58 222.72 484.81 522.54 272.40 296.31 311.58
0.76 0.47 0.93 0.73 0.48 0.56 0.57
0.83 0.47 0.95 0.81 0.5 0.58 0.59
0.29 0.07 0.19 0.31 0.13 0.12 0.14
1.37 0.59 1.30 1.4 0.73 0.79 0.84
5.86 3.64 7.20 5.63 3.70 4.36 4.43
6.45 3.65 7.36 6.31 3.86 4.47 4.58
2.25 0.55 1.52 2.41 0.99 0.94 1.06
10.62 4.6 10.08 10.76 5.65 6.14 6.49
0.21 0.13 0.25 0.20 0.13 0.15 0.16
0.23 0.13 0.26 0.22 0.14 0.16 0.16
0.08 0.02 0.05 0.09 0.03 0.03 0.04
0.38 0.16 0.36 0.38 0.2 0.22 0.23
0.73 0.45 0.89 0.7 0.46 0.54 0.55
0.8 0.45 0.91 0.78 0.48 0.55 0.57
0.28 0.07 0.19 0.3 0.12 0.12 0.13
1.32 0.57 1.24 1.34 0.7 0.76 0.8
9.38 5.83 11.53 9.02 5.93 6.98 7.10
10.33 5.84 11.78 10.1 6.19 7.16 7.33
3.61 0.88 2.41 3.86 1.57 1.5 1.7
16.99 7.39 16.11 17.34 9.06 9.88 10.41
4.09 2.54 5.03 3.94 2.59 3.05 3.10
4.51 2.55 5.14 4.42 2.7 3.12 3.19
1.58 0.38 1.06 1.69 0.69 0.65 0.74
7.44 3.23 7.04 7.59 3.96 4.29 4.53
1.09 0.68 1.34 1.05 0.69 0.81 0.82
1.2 0.68 1.37 1.17 0.72 0.83 0.85
0.42 0.1 0.28 0.45 0.18 0.17 0.2
1.97 0.86 1.87 2.01 1.05 1.14 1.21
Keya River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Tour-Chyan River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Nan-Kan River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65
Health developed a protective dose (Reference Dose) for PFOA and PFOS of 0.14 and 0.075 lg kg-bw1 d1, respectively (MDH, 2007). The Scientific Panel on Contaminants in the Food Chain (CONTAM) established a Tolerable Daily Intake (TDI) for PFOS of 0.15 lg kgbw1 d1 and for PFOA of 1.5 lg kg-bw1 d1 (EFSA, 2008). References of Minnesota for both PFOA and PFOS were chosen to use as the Reference Doses (RfDs) in this assessment, due to its more strict values compared to others. Because there is no recommended RfD for PFDA and other PFC chemicals, potential hazards were calculated for only exposure to PFOS and PFOA in this assessment. Calculated probabilistic distributions of Hazard Index (HI) as non-carcinogenic risk due to exposure to PFOS and PFOA, and a sum of both chemicals from different river water for all age groups are summarized in Table 4. None of the contaminants and sum of them from all rivers for all age groups exceeded RfD, except those from Keya River. The mean values of total HI for all age groups reside near to Keya River exceeding RfD 2.3–4.8 times (SI Fig. 1), corresponded mainly to PFOS with a percentage of 97% (SI Fig. 2). The highest HI through water consumption from Keya River at 95th percentile was 6.65 times higher than RfD (SI Fig. 1). Children aged 1–3 years old using water consumption from Keya River are at the highest risk of exposure to PFOS exhibiting two times higher HI (SI
Fig. 3), while 0.2% of children aged 4–12 years old are under RfD (protective exposure) (SI Fig. 4). The total HI of non-carcinogenic risk of exposure to both chemicals from Nan-Kan River for children aged 1–3 years old was five times (0.2) lower than RfD at 95th percentile, corresponding to almost equal ratio of both chemicals (SI Fig. 2).
4. Discussion Water consumption is the dominant source of exposure to PFCs for the population resides near to contaminated area (Vestergren and Cousins, 2009). The investigations in Europe and U.S. reported 4.3–8.3 times higher levels of PFOA in blood plasma of residents living in contaminated area compared to the reference population (Bartell et al., 2009; Hölzer et al., 2009). In this risk assessment, daily intake of PFOS, PFOA and PFDA with water consumption was estimated in highly contaminated area in Taiwan. Children aged 1–3 years old are at the highest risk of exposure to PFCs through water consumption in Taiwan due to lower body weight. Some studies have conducted in risk assessment for PFCs, mainly estimated potential exposure to PFOA and PFOS from various pathways predicting daily intakes and deriving
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Fig. 3. Average daily intake of PFCs via water consumption supplied from the Xiaoli, Touchien, Tour-Chyan, Nan-Kan, and Keya rivers for different age groups.
the Reference Doses and health based values for water based on conservative exposure assessment. There are no data on comprehensive risk assessment on PFCs, such as multimedia model. The first exposure assessment in USA evaluating the likely pathways of human exposure to PFOA from different environmental media including, ambient air, soil, drinking water, and homegrown vegetables, and estimating the potential intake of this chemical by residents, reside near one of the facilities (DuPont Washington Works Facility) where this chemical was used 53 years ago, was published in 2007. Total aggregate doses for both adult and child were predicted to be ranging from 0.2 to 0.3 lg kg-bw1 d1 with the predominant contribution of ingestion of drinking water (Paustenbach et al., 2007). A recent exposure assessment of PFCs for the general population in western EU countries reviewed the present knowledge of PFC monitoring data in environmental media, including indoor and ambient air, house dust, drinking water and food, relevant for human exposure and estimated the overall exposure (average (and upper) daily intake) to PFOS and PFOA for the general adult population from all potential routes at 1.6 ng kg-bw1 (8.8 ng kg-bw1) and 2.9 ng kg-bw1 (12.6 ng kg-bw1), and from drinking water at 23.3 (130) pg kg-bw1 and 21.7 (86.7) pg kgbw1, respectively (Fromme et al., 2009). Daily intakes of PFOA with water consumption for both child and adult in the present study were lower than those, who reside in highly contaminated area reported by Paustenbach et al. Exposure to both PFOA and PFOS for adults in the present study were much higher than those for general population reported by Fromme et al. (SI Table 2). Residents, especially children aged 1–3 years old, reside near to Keya River are at the greatest risk to exposure to PFCs, mainly to PFOS, through water consumption (upto 6.65 times high risk). Although, the Keya River serves as waste water drainage of SEM plants of HSP, due to the highly persistence in the environment and limited efficient removals from drinking water, the river could be the main source of exposure to PFCs for the residents of this area through different medias, including water consumption, such as drinking water, showering, and cleaning, and diets, such as fish, seafood, livestock, and crops grown based on this river or near to this area. Tittlemier et al. has estimated total exposure to
Perfluorinated Carboxylates and PFOS at 410 ng d1 for Canadian adults consisting the exposures via non-dietary routes, including dust (Kubwabo et al., 2005) and tap water (Tanaka et al., 2006) and treated carpet and apparel (Washburn et al., 2005), and diets composed by beef steak, roast beef, ground beef, luncheon meats, cold cuts and fish from marine and fresh water based on data from Canada and U.S. using conservative exposure estimates (Tittlemier et al., 2007). In coastal countries with industrial activities, high consumption of fish and seafood is one of the main source of human exposure to various environmental toxicants, including PFCs, due to the disposed chemical pollutants into water systems (Naile et al., 2010; Zhao et al., 2011). An exposure assessment of the Flemish population to PFCs realized that an adult consumption of fish and seafood is the dominant source of the intake of PFOS and PFOA (Cornelis et al., 2012). Due to limited available data on different media in Taiwan, it was not possible to conduct multimedia exposure assessment, leading to underestimation of risk of exposure to PFCs. On the other hand, the present conservative risk assessment provides up to date potential risk of PFCs using the probabilistic approach based on Monte Carlo analysis for analyzing variability and uncertainty. Both exposure and risk presented a high degree of uncertainty and variability, associated with the standard deviations in the present study. This can be explained by a wide range of variability of PFC concentrations in water samples collected in the area of study described in the environmental monitoring data reported in the scientific literature. As chemical analysis of environmental PFCs was done in different laboratories in different time period, there can be the analytical uncertainty associated to the environmental concentrations of PFCs. Limited environmental data are available for only certain types of PFCs. Recent studies in Europe and China relating PFC concentrations in river water to the levels in human blood among the residents reside near to the contaminated area support our assessment (Hölzer et al., 2008, 2009; Bartell et al., 2009). In addition, the variability of some exposure parameters would also be important due to the inter-population differences (e.g. body weight, age, water consumption, etc.). Although, in extensive toxicological studies, liver is considered the primary
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D. Chimeddulam, K.-Y. Wu / Chemosphere 90 (2013) 1617–1624 Table 4 Probabilistic HI of non-carcinogenic risk of exposure to PFCs from drinking water for different age groups in different areas. Source of drinking water
Xiaoli River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Touchien River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Keya River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Tour-Chyan River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Nan-Kan River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65
PFOS
PFOA
PFOS + PFOA
Mean
S.D
50th Percentile
95th Percentile
Mean
SD
50th Percentile
95th Percentile
Mean
SD
50th percentile
95th percentile
0.06 0.04 0.07 0.05 0.04 0.04 0.04
0.02 0.02 0.01 0.02 0.01 0.01 0.01
0.05 0.03 0.07 0.05 0.03 0.04 0.04
0.10 0.08 0.10 0.10 0.05 0.06 0.06
0.006 0.004 0.008 0.006 0.004 0.005 0.005
0.002 0.001 0.002 0.003 0.001 0.001 0.001
0.006 0.004 0.008 0.006 0.004 0.005 0.005
0.011 0.005 0.011 0.011 0.006 0.007 0.007
0.063 0.039 0.077 0.061 0.040 0.047 0.048
0.022 0.022 0.015 0.024 0.010 0.009 0.010
0.059 0.034 0.076 0.056 0.039 0.046 0.047
0.10 0.08 0.10 0.11 0.06 0.06 0.07
0.03 0.02 0.04 0.03 0.02 0.03 0.03
0.01 0.00 0.01 0.01 0.01 0.01 0.01
0.03 0.02 0.04 0.03 0.02 0.02 0.02
0.06 0.03 0.06 0.06 0.03 0.03 0.04
0.004 0.003 0.005 0.004 0.003 0.003 0.003
0.002 0.000 0.001 0.001 0.001 0.001 0.001
0.004 0.002 0.005 0.004 0.002 0.003 0.003
0.007 0.003 0.007 0.006 0.004 0.004 0.004
0.038 0.023 0.047 0.036 0.024 0.028 0.029
0.013 0.003 0.009 0.014 0.006 0.005 0.006
0.036 0.023 0.046 0.034 0.023 0.028 0.028
0.06 0.03 0.06 0.06 0.03 0.04 0.04
3.76 2.34 4.61 3.63 2.38 2.80 2.84
1.47 0.36 0.97 1.56 0.63 0.60 0.69
3.51 2.31 4.51 3.33 2.30 2.74 2.76
6.54 2.96 6.34 6.55 3.51 3.88 4.08
0.11 0.07 0.14 0.11 0.07 0.09 0.09
0.04 0.01 0.03 0.05 0.02 0.02 0.02
0.11 0.07 0.14 0.10 0.07 0.08 0.08
0.20 0.09 0.19 0.20 0.11 0.12 0.12
3.873 2.412 4.765 3.713 2.447 2.884 2.931
1.488 0.362 0.970 1.543 0.629 0.599 0.701
3.614 2.385 4.664 3.426 2.366 2.824 2.847
6.65 3.05 6.51 6.62 3.60 3.96 4.21
0.003 0.002 0.003 0.003 0.002 0.002 0.002
0.001 0.000 0.001 0.001 0.000 0.000 0.001
0.003 0.002 0.003 0.002 0.002 0.002 0.002
0.005 0.002 0.005 0.005 0.002 0.003 0.003
0.042 0.026 0.051 0.040 0.026 0.031 0.032
0.016 0.004 0.011 0.017 0.007 0.007 0.008
0.039 0.026 0.050 0.037 0.026 0.030 0.031
0.072 0.033 0.071 0.072 0.039 0.043 0.045
0.045 0.028 0.055 0.043 0.028 0.033 0.034
0.016 0.004 0.010 0.017 0.007 0.007 0.008
0.042 0.027 0.054 0.040 0.027 0.033 0.033
0.07 0.03 0.07 0.07 0.04 0.05 0.05
0.05 0.03 0.07 0.05 0.03 0.04 0.04
0.02 0.01 0.01 0.02 0.01 0.01 0.01
0.05 0.03 0.07 0.05 0.03 0.04 0.04
0.09 0.04 0.09 0.10 0.05 0.06 0.06
0.07 0.04 0.08 0.06 0.04 0.05 0.05
0.03 0.01 0.02 0.03 0.01 0.01 0.01
0.06 0.04 0.08 0.06 0.04 0.05 0.05
0.12 0.05 0.11 0.12 0.06 0.07 0.07
0.122 0.076 0.149 0.117 0.077 0.091 0.092
0.033 0.008 0.022 0.035 0.014 0.013 0.016
0.117 0.075 0.148 0.112 0.076 0.090 0.091
0.18 0.09 0.19 0.18 0.10 0.11 0.12
target organ for exposure to PFOS and PFOA (Biegel et al., 2001; Butenhoff et al., 2002; Seacat et al., 2003; reviewed by Cui et al. (2010)), the target organs for toxicity of other PFCs has not demonstrated yet. Since the limited knowledge about whether all analogue chemicals of this group have the similar or different target organs for toxic effects, the calculation of total risk of this group of chemicals remain unknown.
to total PFCs from water consumption. To reduce the uncertainty in risk assessment of PFCs, it needs to conduct a comprehensive toxicity tests for all PFCs and monitoring to identify as many PFCs as possible in various environmental and other media. Given the limited understanding of the mechanism of toxicity of all other PFCs, further investigation of their potential toxicity is warranted. Acknowledgements
5. Conclusions The potential risk due to exposure to PFCs through water consumption for all age groups of general population in Taiwan was assessed using a probabilistic approach. Daily intake of PFCs through water consumption in highly contaminated area in Taiwan is in similar range to US and other countries, especially in area of HSP with the highest intake of 0.35 lg kg-bw1 d1. Children aged 1–3 years old, are at the highest risk of exposure to PFCs via water consumption. The total HIs of PFOA plus PFOS for all age groups reside near to Keya River 2.4 4.8 times greater than safe levels, corresponded mainly to PFOS. Based on the results we hypothesized for further risk assessment that the residents reside near to Keya River are possibly at high risk of exposure to PFCs through all pathways, particularly, fish and seafood grown in this river. Considering that HI was calculated for only PFOS and PFOA due to the limited available recommended RfD of PFCs, we might underestimate risk for PFCs, but those residents could be at greater risk due to exposure
We acknowledge the authors, who supplied with data on the contamination of river water. This work was supported by a grant from the Taiwan National Science Council, Grant No. 98-2621-M002-016. Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.chemosphere. 2012.08.039. References 3M-Company. 2002. 104-Week dietary chronic toxicity and carcinogenicity study with perfluorooctane sulfonic acid potassium salt (PFOS; T-6295) in Rats. Final Report (US EPA docket AR-226-0956). 3M Company, St. Paul, MN. US Environmental Protection Agency, Washington, DC.
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River water contaminated with perfluorinated compounds potentially posing the greatest risk to young children Dalaijamts Chimeddulam, Kuen-Yuh Wu ⇑ Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, No. 17, ShuJou Rd., Taipei 10055, Taiwan
h i g h l i g h t s " Young children are at the highest risk of exposure to PFCs via water consumption. " Residents reside near to Keya River are at highest risk of exposure to PFCs. " River water were used to surrogate as tapwater. " Deterministic and probabilistic risk assessment methods were used. " Probability density functions for exposure factors were plotted.
a r t i c l e
i n f o
Article history: Received 26 March 2012 Received in revised form 13 August 2012 Accepted 20 August 2012 Available online 27 September 2012 Keywords: Perflourinated compounds Exposure Risk assessment Water consumption Probabilistic analysis Hazard index
a b s t r a c t Although, humans are exposed to perflourinated compounds (PFCs) from various media, water consumption could be an important source for the residents living near to contaminated areas. Since comprehensive multimedia exposure model has not been developed for PFCs, assessment of the potential risk due to exposure to PFCs through direct water consumption could be a conservative estimate. The human health risks derived from the exposure to PFCs through water consumption were assessed for different age groups of general population in Taiwan using probabilistic approach. Based on available data on concentrations of PFCs in river water, exposure to PFOS, PFOA and PFDA via water consumption for different age groups were calculated using deterministic and probabilistic risk assessment methods. The oral non-cancer risks from PFOS, PFOA and their combination, expressed as a Hazard Index (HI), was determined by comparing oral exposure dose (through water intake) with the oral Reference Dose (RfD). The average exposure to PFOS, PFOA and PFDA via water consumption for adults ranged from 0.16 to 220.15, 0.43 to 12.5 and 0.43 to 2.36 ng kg-bw1 d1 and for children 0.13–354.3, 0.35–20.17 and 0.35–3.79 ng kg-bw1 d1, respectively. Probabilistic values of total HIs for all age groups reside near to Keya River exceed the RfD 2.4–4.8 times, corresponding mainly to PFOS with a percentage of 97%. In conclusions, children aged 1–3 years old and the residents reside near to Keya River are at the highest risk of exposure to PFCs via water consumption. Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction Perflourinated chemicals (PFCs) are all anthropogenic organic chemicals, which are used in a wide range of industrial and commerAbbreviations: CATT, C8 Assessment of Toxicity Team; CONTAM, The Scientific Panel on Contaminants in the Food Chain; EFSA, European Food Safety Authority; ELE/OPTO-A, electro/optoelectro A plants; EXPDs, exposure doses; HI, Hazard Index; HSP, Hsinchu Science Park; MDH, Minnesota Department of Health; PDFs, probability density functions; PFCs, perflourinated compounds (chemicals); PFDA, perflourodecanoic acid; PFOA, perflourooctanoic acid; PFOS, perflourooctane sulfonate; RfD, Reference Dose; SEM, semiconductor; TDI, Tolerable Daily Intake; USEPA, US Environmental Protection Agency; WHO, World Health Organization; WVDEP, West Virginia Department of Environmental Protection; WWTPs, waste water treatment plants. ⇑ Corresponding author. Tel.: +886 2 3366 8091; fax: +886 2 3366 8267. E-mail address: [email protected] (K.-Y. Wu). 0045-6535/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.chemosphere.2012.08.039
cial applications due to their persistence to biotic and abiotic degradation (OECD, 2002, 2005; Washburn et al., 2005; Fromme et al., 2009) and of significant health concern due to their adverse effects in animal toxicity and in human epidemiological studies such as, hepatotoxicity, developmental and reproductive toxicity, immunotoxicity, hormonal effects and carcinogenic potency (Thomford, 2001; OECD, 2002; 3M-Company, 2002; Seacat et al., 2002, 2003; Kennedy et al., 2004; Harada et al., 2005; USEPA, 2006; Lau et al., 2007; Andersen et al., 2008; Fei et al., 2008, 2009; Lin et al., 2009a, 2009b; Melzer et al., 2010; Lin et al., 2011; Wang et al., 2011; Bloom et al., 2010). PFCs spread globally in various environmental matrices, including air, surface water, sediments, aquatic invertebrates, fish, and other wildlife, predominanty in the aqueous environment (Martin et al., 2003). Several investigations suggested the discharge from industrial WWTPs as one of the significant point sources for
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PFCs pollution of the aquatic environment (Bossi et al., 2008; Lin et al., 2009c, 2010; Kim et al., 2012). As their environmental fate trend, PFCs have been revealed in drinking water in many countries in US, Europe and Asia Loos et al. (2007) exhibited PFOA and PFOS in tap water drawn from Lake Maggiore in Italy, which had similar concentrations to those in the lake. In some regions of China, concentrations PFOA and PFOS exceeded 10 ng L1, whereas the median concentrations were 4.2–5.4 ng L1 in rivers, which were comparable to those in the US, Europe and Japan (Saito et al., 2004; Jin et al., 2009). These investigations suggested that water treatment steps (sand filtration and chlorination) may not be efficient to remove the contamination of PFCs. (Skutlarek et al., 2006; Loos et al., 2007). Several extensive studies observed relatively high concentrations of PFCs in human serum (e.g. median 374 ng L1 of PFOA) among those, who used water from drinking water supply, which was highly contaminated by those compounds (e.g. 1900–18 600 ng L1 of PFOA) (U.S.EPA, 2001; LHWA, 2005; Skutlarek et al., 2006; Emmett et al., 2006; Loos et al., 2007). These data indicate that drinking water is the dominant source for the population resides near to contaminated areas. In recent years, some efforts utilizing activated carbon filtration, and more advanced water treatment processes succeeded for removals. Nevertheless, these successes are questionable in consistency over time (Bartell et al., 2009; Hölzer et al., 2009; Thompson et al., 2011). As their ubiquitous distribution, humans can be exposed to PFCs through not only drinking water, but also other pathways, including the ingestion with food, such as fish, seafood, livestock, crops and vegetables and house dust; inhalation with air; and water consumption, such as showering, and cleaning. As our current knowledge, few studies have been conducted in risk assessment for PFCs, mainly estimated potential exposure to PFOA and PFOS from various pathways predicting daily intakes deriving the Reference Doses and health based values from drinking water for general adult population in US and Europe (Paustenbach et al., 2007; Fromme et al., 2009). Given that the comprehensive multimedia exposure model has not been developed for human exposure to PFCs due to limited available data on different media, we aimed to maximize the estimates of the potential risk of exposure to PFCs through water consumption using probabilistic assessment. Semiconductor, electrochemical and optoelectronic industries have been grown rapidly in Taiwan. Recent studies reported higher level of PFCs in water area, including industrial and municipal WWTP effluents, rivers and coastal water in Taiwan with the predominant and prevalent exhibition of PFOA, PFOS, PFHxA and PFDA (upto 310, 5440, 406 and 58.2 ng L1, respectively) compared to those reported in other countries (Tseng et al., 2006; Lin et al., 2009c, 2010). The objective of the present study was to assess the human exposure to perflourinated compounds through water consumption for different age groups of general population in Taiwan using probabilistic approach. To the best of our knowledge, this is the first exposure assessment for PFDA through water consumption assessing the risk of all age groups, including children.
Fig. 1. Map of rivers of interest.
rivers located in northern Taiwan, which receive untreated municipal wastewater and agricultural wastewater directly from the cities and suburban area (Fig. 1) (Tseng et al., 2006). Second paper reported in 2009 by Lin et al. identified many different PFCs in river water from Keya, Touchien, and Xiaoli rivers located near to three major sources of potential PFC contamination (Lin et al., 2009c). The Keya River, serves as waste water drainage of semiconductor (SEM) fabrication plant, is greatly impacted by upstream industrial sources from Hsinchu Science Park (HSP). Correspondingly, The Touchien River, serves a population of 790 000, and the Xiaoli River, serves a population of 38 000, are impacted a half of its PFC load by upstream electronics/optoelectronics fabrication (ELE/OPTO) wastewaters and small optoelectronics factory, respectively (Fig. 1). PFOA, PFOS and PFDA were predominant and prevalent in all samples in both papers. Exposure point concentrations and probability density functions (PDFs) of PFOS, PFOA and PFDA in surface water, as an environmental compartment in the risk assessment are summarized in Table 1.
2. Materials and methods
2.2. Exposure assessment
2.1. Concentrations of PFCs in river water
Daily intakes of PFCs were calculated using both deterministic and probabilistic risk assessment methods for different age groups (<0.5; 0.5–0.9; 1–3; 4–12; 13–18; 19–64; >65). To evaluate the exposure doses for humans, PFC concentration values were converted into doses using U.S.EPA (1997) exposure equation, considering the concentration of contaminants in tapwater, the intake rate of tapwater, exposure frequency, exposure duration and body weight of an average individual (U.S.EPA, 1997). The equation is expressed as follows:
For the purposes of exposure assessment, PFC concentrations in the river water were used as surrogates for tapwater concentration. Results of two papers reported the concentrations of PFCs in water area in Taiwan, including industrial and WWTP effluents, rivers and coastal water, were adopted for exposure concentrations for water consumption. First investigation covered the surface water collected from the downstream of Tour-Chyan and Nan-Kan
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Exposure point concentration
SD
Probability density function
References
Distribution
95th Percentile
1.7 1.1 31 11.3 18.1
Lognormal Lognormal Lognormal Lognormal Lognormal
20.28 12.78 363.5 132.5 212.4
Lin (2009) Lin (2009) Lin (2009) Tseng et al. (2006) Tseng et al. (2006)
82 48.9 5440 4 79
8.2 4.9 544 0.4 7.9
Lognormal Lognormal Lognormal Lognormal Lognormal
96.14 57.33 6378 4.69 92.62
Lin (2009) Lin (2009) Lin (2009) Tseng et al. (2006) Tseng et al. (2006)
11 58.2 14.6 14 21
1.1 5.8 1.5 1.4 2.1
Lognormal Lognormal Lognormal Lognormal Lognormal
12.9 68.24 17.12 16.4 24.62
Lin (2009) Lin (2009) Lin (2009) Tseng et al. (2006) Tseng et al. (2006)
PFOA Xiaoli Touchien Keya Tour-Chyan Nan-Kan
17.3 10.9 310 113 181
PFOS Xiaoli Touchien Keya Tour-Chyan Nan-Kan PFDA Xiaoli Touchien Keya Tour-Chyan Nan-Kan
EXPD ¼ ðCW IRÞ=BW
ð1Þ 1
1
where EXPD is the exposure dose (ng kg-bw d ), CW is the concentration in water (ng L1), IR is the ingestion rate (L d1), and BW is the body weight (kg). 2.3. Exposure pathway and factor assumptions Exposure point estimates and probability density functions (PDFs) for exposure factors used to perform deterministic and probability risk assessments of theoretical human exposure to PFCs from consumption water are described in Table 2. Cwater – The concentrations of PFCs in water is supplied from the Tour-Chyan, Nan-Kan, Touchien, and Xiaoli rivers reported by Tseng et al. (2006) and Lin et al. (2009c). It is assumed that residents near to these rivers consume the river water as a sole source of potable water. The mean values and 95% upper confidence limit of the mean concentration were used as a conservative estimate of the mean concentration. IRtapwater – Water consumption was assumed 2.5 L d1 for Taiwanese adults based on data provided by Chen et al. (2003). Using logistic regression analysis on the U.S.EPA recommended tapwater intake for different age groups (in Tables 3–6 of Exposure factor
handbook, (U.S.EPA, 1997)), the average daily intake was adjusted for different age groups in Taiwan (Fig. 2). BW – Average body weight (kg). Average body weights for children aged under 5 years old were adopted from WHO growth standards (WHO, 2006) and others were adopted from the Nutrition and Health Survey in Taiwan (NAHSIT, 1993–1996; Tzeng et al., 1999). Data on body weight from both sources were available as a mean and standard deviation and sample size for every single age. In order to adjust data from above sources to the study, the initial data on body weight for single ages were combined into the different age groups of interest using the following equations:
Magegroup ¼
X
Ni Mi =
X
Ni
ð2Þ
where Magegroup is the mean body weight of an age group, Ni is sample size of i age, and Mi is the mean body weight of i age.
SD2agegroup ¼
X . X X ðNi 1ÞS2i þ ðMi DMÞ Ni 1
ð3Þ
where SDage group is standard deviation of body weight of an age group, Si is standard deviation of body weight of i age, and DM is the mean body weight of an age group.
Table 2 Point estimates and PDFs for exposure factors used to perform deterministic and probability risk assessments of theoretical human exposure to PFOA and PFOS from drinking water. Exposure parameter
Body weight (kg) <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65
Point estimate
SD
Probability density function
References
Distribution
50th Percentile
95th Percentile 8.28 9.8 15.81 49.69 75.34 82.43 80.95
5.21 9.01 12.56 30.11 54.91 64.79 61.2
1.66 0.47 1.85 10.53 11.38 10.01 11.1
Lognormal Lognormal Lognormal Lognormal Lognormal Lognormal Lognormal
4.96 9 12.43 28.42 53.77 64 60.22
Intake rate, drinking water (L d1) <0.5 0.27 0.5–0.9 0.29 1–3 0.8 4–12 1.5 13–18 1.8 19–64 2.5 <65 2.4
0.02 0.03 0.08 0.15 0.18 0.25 0.24
Lognormal Lognormal Lognormal Lognormal Lognormal Lognormal Lognormal
0.27 0.29 0.8 1.49 1.8 2.5 2.4
0.32 0.34 0.94 1.76 2.11 2.93 2.81
WHO (2006) WHO (2006) WHO (2006) NAHSIT (1993–1996) NAHSIT (1993–1996) NAHSIT (1993–1996) NAHSIT (1993–1996) Estimated from U.S.EPA Estimated from U.S.EPA Estimated from U.S.EPA Estimated from U.S.EPA Estimated from U.S.EPA Chen et al. (2003) Estimated from U.S.EPA
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Fig. 2. Logistic regressions of daily intake rate of drinking water for US population and adjusted for Taiwanese population.
2.4. Probabilistic analysis (exposure characterization and uncertainties) The daily intakes of PFOA and PFOS were studied through a probabilistic approach to avoid an underestimation of exposure and risks. A probabilistic analysis (Monte Carlo analysis) was performed to characterize variability and uncertainty in the exposure assumptions and to quantify the range of theoretical EXPDs associated with the exposure pathway (water consumption) for different age groups in accordance with U.S.EPA (1997) guidance. Probability density functions for each parameter were lognormally distributed. The mean point estimates were used to define the boundaries of input values randomly selected in Monte Carlo simulations. Monte Carlo simulations were run 50 000 times using Microsoft Excel™ 2007 and OracleÓ Crystal Ball, Fusion Edition, Release 11.1.1.3.00 software (Oracle Corporation, USA) and some graphs were plotted using SigmaPlot 11.0 software. Assumptions regarding PDFs and the distribution curves for different exposure factors were plotted and the percentile exposures (50th and 95th) for each compound were identified from the graphs. 2.5. Risk characterization Health risks derived from the exposure to PFCs through water consumption were assessed. The oral non-cancer risk, expressed as a Hazard Index (HI), was determined by comparing oral exposure dose (through water intake) with the oral Reference Dose (RfD) for each chemical using the following equation, and summed up HIs to assess total risk.
HI ¼ Exposure dose=RfD
deviation, median and 95th percentiles by all age groups for every river water. Average daily intake of all PFCs from water consumption shown in three tables is integrated in Fig. 3. The average adult exposure to PFOS, PFOA and PFDA via water consumption is ranged 0.16 ± 0.04–220.15 ± 51.14 ng kg-bw1 d1, 0.44 ± 0.1–12.5 ± 2.9 ng kg-bw1 d1, and 0.43 ± 0.1–2.36 ± 0.5 ng kg-bw1 d1, respectively. The average child exposure to PFOS, PFOA and PFDA via water consumption is ranged 0.13 ± 0.02–354.3 ± 72.87 ng kg-bw1 d1, 0.35 ± 0.05–20.17 ± 4.14 ng kg-bw1 d1, and 0.35 ± 0.05–3.79 ± 0.78 ng kg-bw1 d1, respectively. Children aged 1–3 years old are exposed to the highest level of all PFCs from all river water with the average daily intake of up to 0.35 lg kgbw1 d1 followed by infants aged less than 6 months with the average daily intake of up to 0.31 lg kg-bw1 d1. Due to large standard deviation (average daily intake of PFOS is 0.3 ± 0.12 lg kg-bw1 d1), children aged 4–12 years old have the highest intake rate of PFCs at 95th percentile (up to 0.52 lg kg-bw1 d1), while high intake rate for children aged 1–3 years old was up to 0.48 lg kg-bw1 d1. In this study, residents near to Keya River largely exposed to both PFOS and PFOA. Although, Keya River does not serve as water consumption, residents possibly will be exposed to these chemicals through dietary intake of fish and seafood taken from this river and through shower. Excluding this river, the second largest source for exposure to PFOS is the Xiaoli River, whereas the Nan-Kan River is the second largest source for PFOA. Residents reside near to the Touchien River are exposed to higher level of PFDA with the high intake rate up to 5.5 ng kg-bw1 d1 at 95th percentile compared to other two PFCs.
ð4Þ 3.1. Risk characterization
3. Results Deterministic and probabilistic results of environmental exposure to PFCs from water consumption for all age groups of Taiwan are summarized in Table 3. Table shows exposure point estimates of daily intake for each PFC and their probabilistic mean, standard
No risk criteria or standard health guidelines (benchmarks) were established by U.S.EPA. In 2002, the first oral benchmark dose for PFOA (C8) was determined by the C8 Assessment of Toxicity Team (CATT) at the West Virginia Department of Environmental Protection at 4.0 lg kg-bw1 d1 (WVDEP, 2002) (SI Table 1). The Health Risk Assessment Unit in the Minnesota Department of
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PFOA Exposure point estimates
PFOS Probabilistic results Mean
SD
95th Percentile
Exposure point estimates
PFDA Probabilistic results Mean
SD
95th percentile
Exposure point estimates
Probabilistic results Mean
SD
95th percentile
Xiaoli River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65
0.90 0.56 1.10 0.86 0.57 0.67 0.68
0.99 0.56 1.13 0.97 0.59 0.68 0.7
0.34 0.08 0.23 0.37 0.15 0.14 0.16
1.63 0.71 1.54 1.65 0.86 0.94 1.0
4.25 2.64 5.22 4.09 2.69 3.16 3.22
4.68 2.65 5.34 4.60 2.81 3.24 3.32
1.64 0.40 1.09 1.76 0.71 0.68 0.77
7.74 3.36 7.29 7.89 4.10 4.46 4.70
0.57 0.35 0.70 0.55 0.36 0.42 0.43
0.63 0.35 0.72 0.61 0.38 0.43 0.45
0.22 0.05 0.15 0.24 0.09 0.09 0.1
1.04 0.45 0.98 1.05 0.55 0.6 0.63
Touchien River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65
0.56 0.35 0.69 0.54 0.36 0.42 0.43
0.62 0.35 0.71 0.61 0.37 0.43 0.44
0.22 0.05 0.15 0.23 0.09 0.09 0.10
1.03 0.45 0.97 1.05 0.55 0.59 0.63
2.53 1.57 3.11 2.44 1.60 1.89 1.92
2.79 1.58 3.18 2.74 1.67 1.93 1.98
0.98 0.24 0.66 1.05 0.43 0.40 0.46
4.62 2.0 4.35 4.69 2.45 2.66 2.81
3.02 1.87 3.71 2.90 1.91 2.25 2.28
3.33 1.88 3.79 3.24 1.99 2.3 2.36
1.17 0.29 0.78 1.24 0.5 0.48 0.55
5.49 2.38 5.17 5.55 2.90 3.17 3.35
16.07 9.98 19.75 15.44 10.16 11.96 12.16
17.69 10.0 20.17 17.31 10.59 12.25 12.5
6.19 1.51 4.14 6.6 2.69 2.58 2.9
29.24 12.63 27.5 29.67 15.46 16.85 17.83
281.92 175.09 346.50 271.01 178.33 209.91 213.33
310.86 175.75 354.30 305.01 186.36 214.82 220.15
109.37 26.59 72.87 116.59 47.30 45.05 51.14
514.58 222.72 484.81 522.54 272.40 296.31 311.58
0.76 0.47 0.93 0.73 0.48 0.56 0.57
0.83 0.47 0.95 0.81 0.5 0.58 0.59
0.29 0.07 0.19 0.31 0.13 0.12 0.14
1.37 0.59 1.30 1.4 0.73 0.79 0.84
5.86 3.64 7.20 5.63 3.70 4.36 4.43
6.45 3.65 7.36 6.31 3.86 4.47 4.58
2.25 0.55 1.52 2.41 0.99 0.94 1.06
10.62 4.6 10.08 10.76 5.65 6.14 6.49
0.21 0.13 0.25 0.20 0.13 0.15 0.16
0.23 0.13 0.26 0.22 0.14 0.16 0.16
0.08 0.02 0.05 0.09 0.03 0.03 0.04
0.38 0.16 0.36 0.38 0.2 0.22 0.23
0.73 0.45 0.89 0.7 0.46 0.54 0.55
0.8 0.45 0.91 0.78 0.48 0.55 0.57
0.28 0.07 0.19 0.3 0.12 0.12 0.13
1.32 0.57 1.24 1.34 0.7 0.76 0.8
9.38 5.83 11.53 9.02 5.93 6.98 7.10
10.33 5.84 11.78 10.1 6.19 7.16 7.33
3.61 0.88 2.41 3.86 1.57 1.5 1.7
16.99 7.39 16.11 17.34 9.06 9.88 10.41
4.09 2.54 5.03 3.94 2.59 3.05 3.10
4.51 2.55 5.14 4.42 2.7 3.12 3.19
1.58 0.38 1.06 1.69 0.69 0.65 0.74
7.44 3.23 7.04 7.59 3.96 4.29 4.53
1.09 0.68 1.34 1.05 0.69 0.81 0.82
1.2 0.68 1.37 1.17 0.72 0.83 0.85
0.42 0.1 0.28 0.45 0.18 0.17 0.2
1.97 0.86 1.87 2.01 1.05 1.14 1.21
Keya River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Tour-Chyan River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Nan-Kan River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65
Health developed a protective dose (Reference Dose) for PFOA and PFOS of 0.14 and 0.075 lg kg-bw1 d1, respectively (MDH, 2007). The Scientific Panel on Contaminants in the Food Chain (CONTAM) established a Tolerable Daily Intake (TDI) for PFOS of 0.15 lg kgbw1 d1 and for PFOA of 1.5 lg kg-bw1 d1 (EFSA, 2008). References of Minnesota for both PFOA and PFOS were chosen to use as the Reference Doses (RfDs) in this assessment, due to its more strict values compared to others. Because there is no recommended RfD for PFDA and other PFC chemicals, potential hazards were calculated for only exposure to PFOS and PFOA in this assessment. Calculated probabilistic distributions of Hazard Index (HI) as non-carcinogenic risk due to exposure to PFOS and PFOA, and a sum of both chemicals from different river water for all age groups are summarized in Table 4. None of the contaminants and sum of them from all rivers for all age groups exceeded RfD, except those from Keya River. The mean values of total HI for all age groups reside near to Keya River exceeding RfD 2.3–4.8 times (SI Fig. 1), corresponded mainly to PFOS with a percentage of 97% (SI Fig. 2). The highest HI through water consumption from Keya River at 95th percentile was 6.65 times higher than RfD (SI Fig. 1). Children aged 1–3 years old using water consumption from Keya River are at the highest risk of exposure to PFOS exhibiting two times higher HI (SI
Fig. 3), while 0.2% of children aged 4–12 years old are under RfD (protective exposure) (SI Fig. 4). The total HI of non-carcinogenic risk of exposure to both chemicals from Nan-Kan River for children aged 1–3 years old was five times (0.2) lower than RfD at 95th percentile, corresponding to almost equal ratio of both chemicals (SI Fig. 2).
4. Discussion Water consumption is the dominant source of exposure to PFCs for the population resides near to contaminated area (Vestergren and Cousins, 2009). The investigations in Europe and U.S. reported 4.3–8.3 times higher levels of PFOA in blood plasma of residents living in contaminated area compared to the reference population (Bartell et al., 2009; Hölzer et al., 2009). In this risk assessment, daily intake of PFOS, PFOA and PFDA with water consumption was estimated in highly contaminated area in Taiwan. Children aged 1–3 years old are at the highest risk of exposure to PFCs through water consumption in Taiwan due to lower body weight. Some studies have conducted in risk assessment for PFCs, mainly estimated potential exposure to PFOA and PFOS from various pathways predicting daily intakes and deriving
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Fig. 3. Average daily intake of PFCs via water consumption supplied from the Xiaoli, Touchien, Tour-Chyan, Nan-Kan, and Keya rivers for different age groups.
the Reference Doses and health based values for water based on conservative exposure assessment. There are no data on comprehensive risk assessment on PFCs, such as multimedia model. The first exposure assessment in USA evaluating the likely pathways of human exposure to PFOA from different environmental media including, ambient air, soil, drinking water, and homegrown vegetables, and estimating the potential intake of this chemical by residents, reside near one of the facilities (DuPont Washington Works Facility) where this chemical was used 53 years ago, was published in 2007. Total aggregate doses for both adult and child were predicted to be ranging from 0.2 to 0.3 lg kg-bw1 d1 with the predominant contribution of ingestion of drinking water (Paustenbach et al., 2007). A recent exposure assessment of PFCs for the general population in western EU countries reviewed the present knowledge of PFC monitoring data in environmental media, including indoor and ambient air, house dust, drinking water and food, relevant for human exposure and estimated the overall exposure (average (and upper) daily intake) to PFOS and PFOA for the general adult population from all potential routes at 1.6 ng kg-bw1 (8.8 ng kg-bw1) and 2.9 ng kg-bw1 (12.6 ng kg-bw1), and from drinking water at 23.3 (130) pg kg-bw1 and 21.7 (86.7) pg kgbw1, respectively (Fromme et al., 2009). Daily intakes of PFOA with water consumption for both child and adult in the present study were lower than those, who reside in highly contaminated area reported by Paustenbach et al. Exposure to both PFOA and PFOS for adults in the present study were much higher than those for general population reported by Fromme et al. (SI Table 2). Residents, especially children aged 1–3 years old, reside near to Keya River are at the greatest risk to exposure to PFCs, mainly to PFOS, through water consumption (upto 6.65 times high risk). Although, the Keya River serves as waste water drainage of SEM plants of HSP, due to the highly persistence in the environment and limited efficient removals from drinking water, the river could be the main source of exposure to PFCs for the residents of this area through different medias, including water consumption, such as drinking water, showering, and cleaning, and diets, such as fish, seafood, livestock, and crops grown based on this river or near to this area. Tittlemier et al. has estimated total exposure to
Perfluorinated Carboxylates and PFOS at 410 ng d1 for Canadian adults consisting the exposures via non-dietary routes, including dust (Kubwabo et al., 2005) and tap water (Tanaka et al., 2006) and treated carpet and apparel (Washburn et al., 2005), and diets composed by beef steak, roast beef, ground beef, luncheon meats, cold cuts and fish from marine and fresh water based on data from Canada and U.S. using conservative exposure estimates (Tittlemier et al., 2007). In coastal countries with industrial activities, high consumption of fish and seafood is one of the main source of human exposure to various environmental toxicants, including PFCs, due to the disposed chemical pollutants into water systems (Naile et al., 2010; Zhao et al., 2011). An exposure assessment of the Flemish population to PFCs realized that an adult consumption of fish and seafood is the dominant source of the intake of PFOS and PFOA (Cornelis et al., 2012). Due to limited available data on different media in Taiwan, it was not possible to conduct multimedia exposure assessment, leading to underestimation of risk of exposure to PFCs. On the other hand, the present conservative risk assessment provides up to date potential risk of PFCs using the probabilistic approach based on Monte Carlo analysis for analyzing variability and uncertainty. Both exposure and risk presented a high degree of uncertainty and variability, associated with the standard deviations in the present study. This can be explained by a wide range of variability of PFC concentrations in water samples collected in the area of study described in the environmental monitoring data reported in the scientific literature. As chemical analysis of environmental PFCs was done in different laboratories in different time period, there can be the analytical uncertainty associated to the environmental concentrations of PFCs. Limited environmental data are available for only certain types of PFCs. Recent studies in Europe and China relating PFC concentrations in river water to the levels in human blood among the residents reside near to the contaminated area support our assessment (Hölzer et al., 2008, 2009; Bartell et al., 2009). In addition, the variability of some exposure parameters would also be important due to the inter-population differences (e.g. body weight, age, water consumption, etc.). Although, in extensive toxicological studies, liver is considered the primary
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Xiaoli River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Touchien River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Keya River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Tour-Chyan River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65 Nan-Kan River <0.5 0.5–0.9 1–3 4–12 13–18 19–64 <65
PFOS
PFOA
PFOS + PFOA
Mean
S.D
50th Percentile
95th Percentile
Mean
SD
50th Percentile
95th Percentile
Mean
SD
50th percentile
95th percentile
0.06 0.04 0.07 0.05 0.04 0.04 0.04
0.02 0.02 0.01 0.02 0.01 0.01 0.01
0.05 0.03 0.07 0.05 0.03 0.04 0.04
0.10 0.08 0.10 0.10 0.05 0.06 0.06
0.006 0.004 0.008 0.006 0.004 0.005 0.005
0.002 0.001 0.002 0.003 0.001 0.001 0.001
0.006 0.004 0.008 0.006 0.004 0.005 0.005
0.011 0.005 0.011 0.011 0.006 0.007 0.007
0.063 0.039 0.077 0.061 0.040 0.047 0.048
0.022 0.022 0.015 0.024 0.010 0.009 0.010
0.059 0.034 0.076 0.056 0.039 0.046 0.047
0.10 0.08 0.10 0.11 0.06 0.06 0.07
0.03 0.02 0.04 0.03 0.02 0.03 0.03
0.01 0.00 0.01 0.01 0.01 0.01 0.01
0.03 0.02 0.04 0.03 0.02 0.02 0.02
0.06 0.03 0.06 0.06 0.03 0.03 0.04
0.004 0.003 0.005 0.004 0.003 0.003 0.003
0.002 0.000 0.001 0.001 0.001 0.001 0.001
0.004 0.002 0.005 0.004 0.002 0.003 0.003
0.007 0.003 0.007 0.006 0.004 0.004 0.004
0.038 0.023 0.047 0.036 0.024 0.028 0.029
0.013 0.003 0.009 0.014 0.006 0.005 0.006
0.036 0.023 0.046 0.034 0.023 0.028 0.028
0.06 0.03 0.06 0.06 0.03 0.04 0.04
3.76 2.34 4.61 3.63 2.38 2.80 2.84
1.47 0.36 0.97 1.56 0.63 0.60 0.69
3.51 2.31 4.51 3.33 2.30 2.74 2.76
6.54 2.96 6.34 6.55 3.51 3.88 4.08
0.11 0.07 0.14 0.11 0.07 0.09 0.09
0.04 0.01 0.03 0.05 0.02 0.02 0.02
0.11 0.07 0.14 0.10 0.07 0.08 0.08
0.20 0.09 0.19 0.20 0.11 0.12 0.12
3.873 2.412 4.765 3.713 2.447 2.884 2.931
1.488 0.362 0.970 1.543 0.629 0.599 0.701
3.614 2.385 4.664 3.426 2.366 2.824 2.847
6.65 3.05 6.51 6.62 3.60 3.96 4.21
0.003 0.002 0.003 0.003 0.002 0.002 0.002
0.001 0.000 0.001 0.001 0.000 0.000 0.001
0.003 0.002 0.003 0.002 0.002 0.002 0.002
0.005 0.002 0.005 0.005 0.002 0.003 0.003
0.042 0.026 0.051 0.040 0.026 0.031 0.032
0.016 0.004 0.011 0.017 0.007 0.007 0.008
0.039 0.026 0.050 0.037 0.026 0.030 0.031
0.072 0.033 0.071 0.072 0.039 0.043 0.045
0.045 0.028 0.055 0.043 0.028 0.033 0.034
0.016 0.004 0.010 0.017 0.007 0.007 0.008
0.042 0.027 0.054 0.040 0.027 0.033 0.033
0.07 0.03 0.07 0.07 0.04 0.05 0.05
0.05 0.03 0.07 0.05 0.03 0.04 0.04
0.02 0.01 0.01 0.02 0.01 0.01 0.01
0.05 0.03 0.07 0.05 0.03 0.04 0.04
0.09 0.04 0.09 0.10 0.05 0.06 0.06
0.07 0.04 0.08 0.06 0.04 0.05 0.05
0.03 0.01 0.02 0.03 0.01 0.01 0.01
0.06 0.04 0.08 0.06 0.04 0.05 0.05
0.12 0.05 0.11 0.12 0.06 0.07 0.07
0.122 0.076 0.149 0.117 0.077 0.091 0.092
0.033 0.008 0.022 0.035 0.014 0.013 0.016
0.117 0.075 0.148 0.112 0.076 0.090 0.091
0.18 0.09 0.19 0.18 0.10 0.11 0.12
target organ for exposure to PFOS and PFOA (Biegel et al., 2001; Butenhoff et al., 2002; Seacat et al., 2003; reviewed by Cui et al. (2010)), the target organs for toxicity of other PFCs has not demonstrated yet. Since the limited knowledge about whether all analogue chemicals of this group have the similar or different target organs for toxic effects, the calculation of total risk of this group of chemicals remain unknown.
to total PFCs from water consumption. To reduce the uncertainty in risk assessment of PFCs, it needs to conduct a comprehensive toxicity tests for all PFCs and monitoring to identify as many PFCs as possible in various environmental and other media. Given the limited understanding of the mechanism of toxicity of all other PFCs, further investigation of their potential toxicity is warranted. Acknowledgements
5. Conclusions The potential risk due to exposure to PFCs through water consumption for all age groups of general population in Taiwan was assessed using a probabilistic approach. Daily intake of PFCs through water consumption in highly contaminated area in Taiwan is in similar range to US and other countries, especially in area of HSP with the highest intake of 0.35 lg kg-bw1 d1. Children aged 1–3 years old, are at the highest risk of exposure to PFCs via water consumption. The total HIs of PFOA plus PFOS for all age groups reside near to Keya River 2.4 4.8 times greater than safe levels, corresponded mainly to PFOS. Based on the results we hypothesized for further risk assessment that the residents reside near to Keya River are possibly at high risk of exposure to PFCs through all pathways, particularly, fish and seafood grown in this river. Considering that HI was calculated for only PFOS and PFOA due to the limited available recommended RfD of PFCs, we might underestimate risk for PFCs, but those residents could be at greater risk due to exposure
We acknowledge the authors, who supplied with data on the contamination of river water. This work was supported by a grant from the Taiwan National Science Council, Grant No. 98-2621-M002-016. Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.chemosphere. 2012.08.039. References 3M-Company. 2002. 104-Week dietary chronic toxicity and carcinogenicity study with perfluorooctane sulfonic acid potassium salt (PFOS; T-6295) in Rats. Final Report (US EPA docket AR-226-0956). 3M Company, St. Paul, MN. US Environmental Protection Agency, Washington, DC.
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