Environ. Sci. Technol. 2010, 44, 3572–3579
Perfluorochemicals in Meat, Eggs and Indoor Dust in China: Assessment of Sources and Pathways of Human Exposure to Perfluorochemicals T A O Z H A N G , †,‡ H O N G W E N S U N , * ,† QIAN WU,‡ XIAN ZHONG ZHANG,† SE HUN YUN,‡ AND K U R U N T H A C H A L A M K A N N A N * ,‡,§ MOE Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300071, China, Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, New York, and State Key Laboratory of Urban Water Resources & Environment, IJRC-PTS, Harbin Institute of Technology, Harbin 150090, China
Received January 4, 2010. Revised manuscript received March 16, 2010. Accepted March 29, 2010.
In this study, 10 perfluorochemicals (PFCs) were measured in meat, meat products, and eggs, and in indoor dust, collected in China. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were the most frequently detected PFCs in these samples. Mean concentrations of PFOS and PFOA in foodstuffs were in the range of 0.05-1.99 ng/g fresh wt and 0.06-12.5 ng/g fresh wt, respectively. The mean concentrations of PFOA, perfluoroheptanoic acid (PFHpA), and PFOS in indoor dust were 205, 14.0, and 4.86 ng/g, dry wt, respectively. The estimated daily intake of PFOS and PFOA from meat, meat products and eggs (EDImeat&eggs) ranged from 6.00 to 9.64 ng/d and from 254 to 576 ng/d, respectively, when the values below the limit of quantitation (LOQ) were assigned as 0, and from 8.80 to 15.0 ng/d and from 255 to 577 ng/d, respectively, when the values below the LOQ were set at 1/2LOQ. The EDImeat&eggs of PFOS and PFOA increased with increasing family income. The estimated daily intake of PFOS and PFOA through inhalation of dust (EDIdust) ranged from 0.23 to 0.31 ng/d and from 9.68 to 13.4 ng/d, respectively. The daily intakes of PFOS and PFOA from the consumption of meat, meat products, and eggs, and from dust ingestion, as calculated from our samples in this study, were compared with estimated daily intake of PFCs reported from the concentrations in drinking water, fish and seafood from China. Our calculations indicate that dietary sources (EDIdietary) account for the overwhelming proportion of (>99% for PFOS and 98% for PFOA) total daily intake (TDI) in adults. The analyzed foodstuffs (meat, meat products, and eggs) were not the major contributors to dietary exposure to PFOS, whereas, meat was the primary contributor to dietary exposure to PFOA.
* Address correspondence to either author. Phone: 1-518-4740015 (K.K.); 86-22-23509241 (H.W.S.). Fax: 1-518-473-2895 (K.K.); 8622-23509241 (H.W.S.). E-mail:
[email protected] (K.K.);
[email protected] (H.W.S.). † Nankai University. ‡ Wadsworth Center and State University of New York at Albany. § Harbin Institute of Technology. 3572
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Introduction Because of their unique physicochemical characteristics, such as chemical and thermal inertness, low surface energy, and high surface-active properties, perfluorochemicals (PFCs) have been used in a very wide variety of consumer and industrial applications, including protective coatings for fabrics and carpets, paper coatings, paints, cosmetics, and fire-fighting foams (1). However, several PFCs have been shown to be persistent, bioaccumulative, and toxic. Perfluorooctane sulfonate (PFOS) has been listed as a Persistent Organic Pollutant under the Stockholm Convention since May 2009 (2). PFCs, especially PFOS and PFOA, are ubiquitous in human blood (3–5). Blood samples from people in China and the U.S. contain some of the highest measured concentrations of PFCs (3, 4). Nevertheless, the sources and pathways of human exposure to PFCs are not well-understood. A few studies reported the occurrence of PFCs in foodstuffs, and showed the significance of diet as a pathway of human exposure (6–13). Those studies reported mean values for the estimated daily intake of PFCs via diet (EDIdietary) in the range of 1.0-4.0 ng/kg body weight (bw)/d, for populations in Germany (6), Spain (7, 8), Canada (9, 10), and Japan (11). In the UK (12), the EDIdietary values were very high: 100 ng/kg bw/d for PFOS, and 70 ng/kg bw/d for PFOA. Consumption of traditional food items such as caribou meat and liver by the native population in Nunavut, Canada, contributed to high PFC exposures in that region (10). A few studies have shown that fish and seafood consumption is a major source of PFC exposure in humans (7, 14, 15). Unquestionably, humans are exposed to PFCs via diet; however, the contribution of diet to total exposure is still not clear. Indoor dust can be an important source of PFC exposure (16–18). A study from the U.S. showed that the estimated daily intake of PFCs via indoor dust ingestion (EDIdust) was 92 ng/d for children and 46 ng/d for adults (17). Percent contribution of dust to human PFC exposure was reported to be in the range of 0.4-5% for adults, and 5-55% for toddlers (18). In addition to diet and dust, the general population is exposed to PFCs via inhalation of indoor/outdoor air, soil ingestion, and consumption of drinking water (19–24). However, the current challenge is to figure out the relative magnitude of the contribution by the various sources (diet, drinking water, indoor air, and indoor dust). This issue is especially significant in countries like China, where the concentrations of PFCs in human blood are high (4) and no regulations are in place to restrict the production or usage of PFCs. Elevated concentrations of PFCs have been reported in drinking water, seafood, and breast milk from China (15, 22, 25). Therefore, assessment of sources and pathways of human exposure to PFCs is critical, if we are to develop strategies for mitigating human exposure to these compounds. In the present study, concentrations of 10 PFCs were measured in meat, meat products, eggs, and in indoor dust, to enable estimation of daily intake via meat, meat products and eggs (EDImeat&eggs) and dust (EDIdust) in China. The estimated daily intake of PFCs measured in meat, meat products, eggs, and indoor dust in this study were compared with reported concentrations and intakes of PFCs in seafood (15), breast milk (25), and drinking water (22) from China. Results from the current study and previously published intake values (6–12) were compiled to enable assessment of cumulative exposure to PFCs by the Chinese populace. 10.1021/es1000159
2010 American Chemical Society
Published on Web 04/08/2010
Materials and Methods Samples Collection and Preparation. During JanuaryFebruary 2009, frequently consumed animal-origin foods were collected. These included 20 meat samples (pork, beef, chicken, and goat meat), meat products including 59 edible animal liver (pork, beef, chicken, duck, and goat liver) and 15 animal blood cake samples (pork, beef, duck, and goat blood), and 31 egg samples (chicken and duck eggs). Indoor dust (n ) 28) was collected during January-July 2009. The samples were collected from 17 cities in 15 provinces and municipalities in China; the sampling locations were widely distributed, in northern, northwestern, southwestern, central, and southern areas of the country. Detailed information on the samples is presented in Supporting Information (SI) Table S1 and Figure S1. Meat, liver, blood cake, and eggs were purchased from randomly chosen local markets or grocery stores (therefore, meat and meat product samples were not from the same animal). Multiple samples of a given type were collected from several grocery stores and pooled. Indoor dust samples were collected from individual homes (n ) 12), offices (n ) 11), and student dorms (n ) 5) in Nanchang, Shanghai, Beijing, and Tianjin, by sweeping of floors or collection of dust from vacuum cleaners. The concentrations of target analytes were calculated and expressed as ng/g fresh weight for food samples, and as ng/g, dry weight for dust samples. Meat and animal liver samples were freeze-dried with a Telstar Laboratory freeze-dryer Cryodos-80 for 24 h, and the moisture content of the samples was recorded to enable reporting of PFC concentrations on a fresh weight basis. Dried meat and liver samples, blood cake, and egg samples were homogenized. All the samples were stored at -20 °C in polypropylene tubes for the analysis of PFCs. Meat, liver, blood cake, and egg samples were extracted by ion-pair method whereas dust was extracted by methanol extaction. The procedures for extraction are given in the SI. Instrumental Analysis. Concentrations of 10 PFCs, namely, perfluorohexansulfonate (PFHxS), PFOS, perfluorodecanesulfonate (PFDS), perfluorooctanesulfonamide (PFOSA), perfluoroheptanoic acid (PFHpA), PFOA, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), and perfluorododecanoic acid (PFDoDA), were determined by using an Agilent 1100 Series high performance liquid chromatograph (HPLC) coupled with an Applied Biosystems API 2000 electrospray triple-quadrupole mass spectrometer (ESI-MS/MS) (5, 26, 27). Further details of the instrumental analysis are given in the SI. Quality Assurance and Quality Control. Matrix-spike recoveries of individual PFCs through the analytical procedure were determined by spiking of 10 PFCs into randomly selected samples from each sample type. PFCs were spiked into meat (n ) 3) and blood cake (n ) 3) at 1 ng; they were spiked into egg (n ) 3) and indoor dust (n ) 3) samples at 10 ng; and they were spiked into liver samples at 1 ng (n ) 3) and 10 ng (n ) 3) levels. Four 13C-labeled internal standards (13C4-PFOS, 13C4-PFOA, 13C2-PFNA, 13C2-PFDA) were spiked (5 ng each) into all samples prior to extraction. Recoveries of PFCs spiked into sample matrixes ranged from 69 ( 5% (mean ( SD) to 139 ( 11% for meat, from 51 ( 14% to 155 ( 22% for liver, from 62 ( 6% to 158 ( 13% for blood cake, and from 75 ( 7% to 158 ( 8% for eggs. Recoveries ranged from 72 ( 16% to 134 ( 22% for indoor dust. A few exceptions, with high/low recoveries were noted: PFNA and PFDA in meat, PFHxS and PFOSA in liver, PFUnDA in blood cake, PFOSA in eggs and PFOSA and PFDoDA in indoor dust, showed those particular recoveries either below 50% or greater than 150%. However, these PFCs were rarely found in corresponding sample matrices, and the high/low recoveries, therefore, did not affect the interpretation of results.
Method precision was good, with relative standard deviations (RSDs) for three extractions of each sample type with the range of 1-25% for all PFCs. Mean recoveries of internal standards for each sample type were 136 ( 24% for meat, 121 ( 23% for liver, 125 ( 24% for blood cake, 127 ( 27% for eggs, and 113 ( 12% for indoor dust (SI Table S2). The concentrations of PFOS, PFOA, PFNA, and PFDA were not corrected by recoveries of respective internal standard. Quantification was performed using linear regressions (r2 > 0.99 for all analytes) generated from an eight-point calibration standard prepared in methanol, at concentrations ranging from 0.1 to 20 ng/mL (except for dust, for which the calibration range was 0.1-100 ng/mL). Calibration standards were injected before and after analysis of a batch of 20 samples, as a check for instrument response. Methanol was injected after every batch of 5-10 samples as a check for instrumental blanks and memory effects. Procedural blanks were prepared for every 20 samples to monitor for contamination in reagents and glassware. All instrumental blanks and procedural blanks were free of detectable concentrations of the target PFCs analyzed, except for PFOA, which was found in blanks at 0.06 ( 0.08 ng/g (on a fresh weight basis). The limit of quantitation (LOQ) was determined based on the linear range of the calibration curve; concentrations in samples which were at least 3-fold greater than the lowest acceptable standard concentration were considered to be valid. The LOQ for the analyte of interest was (ng/g fresh weight): 0.21 ( 0.15 (PFHxS), 0.20 ( 0.14 (PFOS), 0.19 ( 0.12 (PFDS), 0.20 ( 0.15 (PFOSA), 0.38 ( 0.23 (PFHpA), 0.25 ( 0.13 (PFOA), 0.26 ( 0.24 (PFNA), 0.26 ( 0.21 (PFDA), 0.71 ( 0.36 (PFUnDA), and 1.11 ( 0.58 (PFDoDA). Dilution or concentration factors and the mass of samples taken for analysis were included in the calculation of LOQ. Reported concentrations were subtracted from the highest values found for instrumental and procedural blanks. Daily Intake Estimation. In 2004, questionnaire-based dietary pattern and nutrition survey was conducted by the Chinese Center for Disease Control and Prevention in 18 cities and 40 counties, of nine provinces of China (28). The consumption patterns of meat, animal liver, animal blood cake, and eggs by Chinese toddlers (2-5 yrs), children and adolescents (6-17 yrs), and adults (g18 yrs) are shown in SI Table S3. Consumption information for pork, beef, goat, chicken, and eggs has been reported (28, 29). The consumption data for animal liver and blood cake were calculated from the ratio of liver or blood weight to muscle weight (30) due to lack of data on daily intakes values from China. The EDImeat&eggs of PFCs was calculated through multiplication of mean PFC concentrations in meat and meat products, eggs by the amount consumed (equation is shown in SI Table S4). Human exposure to PFCs through ingestion and dermal absorption of indoor dust was estimated from the mean PFC concentration found in indoor dust in this study, through the application of exposure/ingestion factors recommended by the U.S. Environmental Protection Agency (USEPA) (31–33). Exposure from indoor dust can occur through inhalation, oral ingestion, and dermal absorption (32, 34). Human exposure to PFCs through inhalation and dermal absorption of dust was estimated based on the assumption that only a small fraction (3%) of the dose is absorbed through the skin (35–37). Reported concentrations of PFCs in indoor air from Japan (20) were used in the calculation of intake from inhalation. The equations used for the calculation of human exposure through inhalation of air, dust ingestion, and dermal absorption of dust are given in SI Table S4. For comparison of daily intake of PFCs in adults, we also estimated daily intake of PFCs in infants (0-1 yrs) through breast milk (EDIbreast milk) ingestion, based on reported PFCs levels in Chinese breast milk (25) and daily ingestion rate by infants (600 mL/d) (25). The estimated daily intake of PFCs VOL. 44, NO. 9, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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was performed for Chinese males and females with three family income categories (low, medium and high) and four age groups: infants (0-1 yrs), toddlers (2-5 yrs), children and adolescents (6-17 yrs), and adults (g18 yrs), as suggested by the Chinese Center for Disease Control and Prevention (28). Statistical Analysis. Differences between estimated daily intake of PFCs through meat meat products, eggs and inhalation for different age/gender/income groups, and differences between PFC concentrations in dust from each city or each microenvironment, were evaluated by analysis of variance (ANOVA). Data were analyzed with the statistical software package SPSS 16.0 (SPSS Inc., 2008).
Results and Discussion PFCs in Meat, Meat Products, and Eggs. The mean concentrations of individual PFCs and the sum (total PFCs) in meat, animal liver, animal blood cake, and eggs are presented in Table 1. Eight PFCs were detected at concentrations g LOQ in at least one food sample. PFOA was the most frequently detected compound, found in 85 of 125 food samples analyzed; it was followed by PFOS (41 of 125) and PFNA (14 of 125). PFOSA and PFDoDA were not detected in any of the samples analyzed. The highest mean concentration of PFOA was found in chicken meat (12.5 ng/g), and the highest mean concentration of PFOS was found in pork liver (1.99 ng/g). The highest total PFC concentration was found in chicken meat (12.7 ng/g), followed by pork meat (6.38 ng/g), pork liver (4.47 ng/g) and beef meat (4.43 ng/g). Total PFC concentrations were >1 ng/g in all of the samples of meat and liver (except for chicken liver), with a concentration range of 1.45-12.7 ng/g. Relatively low total PFC concentrations were found in eggs (0.38-1.21 ng/g) and animal blood cake (0.50 to 1.03 ng/g). The measured concentrations of PFCs in analyzed foodstuffs (meat, meat products, and eggs), in general, were higher than or comparable to concentrations reported previously from other countries (6–12). In Spain, the highest reported concentrations of PFOS, PFOA, and PFHpA were between
