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Keywords:

  • Perfluorinated compounds;
  • Farmed freshwater fish;
  • Tissue distribution

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS AND DISCUSSION
  6. SUPPLEMENTAL DATA
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

In the present study, the levels of 14 perfluorinated compounds (PFCs) were analyzed in the blood, liver, muscle, brain, and eggs of popular farmed freshwater fish from Beijing. Perfluorooctane sulfonate (PFOS) was the predominant compound in all samples, with the highest concentration at 70.7 ng/g wet weight. The highest mean levels of PFOS in all tissues were observed in bighead (1.48–22.5 ng/g wet wt) and the lowest in tilapia (0.260–1.63 ng/g wet wt). In addition, perfluoroundecanoic acid was the second dominant PFC in blood, liver, muscle, and eggs, with the highest concentration at 19.2 ng/g wet weight. However, perfluorodecanoic acid levels (less than the limit of detection [LOD] to 0.963 ng/g wet wt) were similar to or slightly higher than perfluoroundecanoic acid levels (<LOD to 0.918 ng/g wet wt) in the brain. Generally, the highest mean concentrations of PFOS and total PFCs were found in fish blood, followed by liver, brain, and muscle, further supporting the premise that PFOS can bind more easily to serum proteins than to fatty tissues. The egg to liver ratios as maternal transfer ratios were calculated for PFOS, ranging from 0.93 to 2.0. Furthermore, based on consumption information for fish in Beijing, the human dietary intake of PFCs through fish consumption were estimated at 0.24 ng/kg/d for PFOS and 0.44 ng/kg/d for total PFC. These results indicate a low health risk posed from PFCs to the residents of Beijing through the consumption of fish. Environ. Toxicol. Chem. 2012;31:717–723. © 2012 SETAC


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS AND DISCUSSION
  6. SUPPLEMENTAL DATA
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

Perfluorinated compounds (PFCs) are a family of manmade fluorinated organic compounds, which have been produced for several decades. Because of their oleophobic and hydrophobic properties, they are used extensively in food packaging, textile coatings, lubricants, surfactants, fire-fighting foams, and nonstick coatings for cookware 1, 2. There have been growing concerns about the environmental behavior and potential toxicities of PFCs, particularly perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). Perfluorooctane sulfonate and PFOA are intermediate compounds during the synthesis of other PFCs and are the final metabolites or degradation products of some related compounds 3. Recent studies revealed that PFCs are widespread in the environment and can be bioaccumulated in wildlife and humans 4, 5. Perfluorooctane sulfonate can bind strongly to proteins and accumulate mainly in the liver, blood serum, kidney, and heart. Moreover, maternal transfer to the embryo has also been reported for PFOS 6. Toxicology studies on animals have shown that exposure to PFCs during the embryonic stage causes harmful effects in oviparous organisms and can have adverse effects on their offspring 7. A laboratory study of the aquatic toxicity of PFCs on zebrafish embryos showed that PFOS could cause larval abnormalities 8. Another recent report also indicated that exposure of maternal zebrafish to low concentrations of PFOS could result in deformity and mortality of the offspring 9.

In recent years, human exposure to PFCs by the intake of food, drinking water, air, and indoor dust has drawn growing concerns from environmental scientists 10, and a previous study indicated that humans are exposed to PFCs mainly through food consumption, accounting for approximately 60% of total exposure 11. In particular, the levels of PFCs in fish were relatively high among the foodstuffs analyzed, which implied that the intake of contaminated fish may be a significant source of PFCs in humans 12, 13. Several studies showed that PFC levels in human blood positively correlated with the consumption of fish (or marine mammals) 14–16. Several studies have also documented the presence of PFCs in edible fish, causing great concern in many countries 11, 13, 17–19. In China, PFC residues have been investigated in seven types of seafood (including fish) collected from two coastal cities. The levels of PFOS in these seafood samples ranged from 0.3 to 13.9 ng/g wet weight 20. However, very little information is available on the levels of PFCs in the farmed freshwater fish of China, especially regarding their tissue distribution.

Farmed freshwater fish are the main fish products consumed in China, especially for those living in inland cities. In recent years, human consumption of farmed fish has increased because of the considerable growth and production of aquaculture worldwide. Especially for China, aquaculture production increased at a growth rate of 10.4% per year from 1970 to 2008 21 (http://www.fao.org/docrep/013/i1820e/i1820e00.htm). China has also become the largest fish-producing country and exporter in the world, with an estimated fish production of 47.5 million metric tons in 2008. Farmed fish (32.7 million tons) accounted for 68.8% of the total production, indicating that most fish consumed were farmed in China 21 (http://www.fao.org/docrep/013/i1820e/i1820e00.htm). The potential health risk from exposure to polybrominated diphenyl ethers, dichlorodiphenyltrichloroethane, and so on via farmed fish consumption in the coastal region of South China has been assessed in previous studies 22, 23. However, there is limited information on the exposure to PFCs via farmed fish consumption in China.

In the present study, we investigated the levels of PFOS and 13 other fluorochemicals in popular farmed freshwater fish, including grass carp, snakehead, crucian carp, common carp, tilapia, and bighead purchased in Beijing, China. We also assessed their tissue distribution (blood, liver, muscle, brain, and eggs); the accumulation of PFOS, PFOA, perluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA) in the liver; and the maternal transfer of PFOS. Finally, we estimated the dietary exposure to PFCs by fish consumption. To our knowledge, this is the first study on the tissue distribution of PFCs in farmed freshwater fish. The present study is important for understanding the human health risk factor of PFCs associated with fish consumption.

MATERIALS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS AND DISCUSSION
  6. SUPPLEMENTAL DATA
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

Sampling

In July, 2009, farmed fish were collected randomly from four downtown markets in Beijing, China. Species of fish were common carp (Cyprinus carpio, n = 10), crucian carp (Carassius auratus, n = 13), grass carp (Ctenopharyngodon idellus, n = 10), bighead (Aristichthys nobilis, n = 12), snakehead (Ophicephalus argus, n = 8), and tilapia (Tilapia, n = 7). Two or three fish of the same species were purchased from each market. All fish were alive during collection. Whole-blood samples (n = 60) were collected by syringe. Before collection of fish blood, the live fish were euthanized by a blow to the head. Then, 5 ml whole blood was drawn from the caudal vein into a Becton Dickinson Vacutainer tube (Becton Dickinson Vacutainer System) with ethylenediaminetetraacetic acid. The fish were then dissected to extract the liver (n = 60), brain (n = 60), muscle (n = 60), and eggs (n = 18), which were cleaned using purified water to remove blood and were then homogenized. In total, 258 samples were analyzed for 14 PFCs. All samples were kept at −20°C until further analysis.

Chemicals

Fourteen PFCs (perfluoroheptanoic acid, PFOA, perfluorononanoic acid, PFDA, perfluorododecanoic acid, perfluorotetradecanoic acid, PFUnDA, perfluorotridecanoic acid, nonafluorobutane-1-sulfonic acid, perfluorohexane sulfonate, PFOS, perfluoro-1-octanesulfonamide, 2-perfluorooctyl ethanoic acid, and 2H-perfluoro-2-decenoic acid) were analyzed. Detailed information on chemicals is given in the Supplemental Data.

Sample pretreatment and instrumental analysis

Two different modified extraction methods, ion-pairing and alkaline digestion, were used for the pretreatment of organ (blood, liver, brain, and eggs) and muscle samples, respectively. The samples were thawed at 4°C and placed in a polypropylene centrifuge tube, which had been precleaned with methanol, and then internal standards (perfluoro-1-[1,2,3,4-13C4] octanesulfonate and perfluoro-n-[1,2,3,4-13C4] octanoic acid at 2 ng) were added. For organ samples, 0.2 to 0.5 g of each sample was pretreated using the ion-pairing liquid–liquid extraction method, which has been described in detail 24. For muscle samples, 1.0 g of each sample was freeze dried, ground to powder, and extracted using the alkaline digestion method, which was described in our previous article 25. Concentrated extracts of each sample (viscera or muscle) were diluted to 40 ml using water in a polypropylene container and loaded onto a Waters Oasis WAX single-use cartridge (6 cc/150 mg) for cleanup. Details on the cleanup procedure are referred to in our previous article 25. Blanks with methanol, treated as real samples in all steps, were processed with each batch.

An analysis of 14 PFCs was performed by using high-performance liquid chromatography (P680 pump, Ultimate 3000 autosampler; Dionex) coupled with electrospray ionization tandem mass spectrometry (API 3200, Applied Biosystems/MDS SCIEX). The experimental conditions for electrospray ionization tandem mass spectrometry are shown in Supplemental Data, Table S1. A 10-µl aliquot was injected into a Dionex Acclaim 120 C18 column (5 µm, 4.6 mm i.d. × 150 mm length) for analysis. The mobile phase was a mixture of methanol (eluent A) and 50 mM ammonium acetate in water (eluent B) under the gradient mode, and the flow rate was 1.0 ml/min. The solvent gradient started at 28% B, was ramped over 4 min to 5% B, held for 3 min at 5% B, increased to 28% B, and then held at this level until 10 min. The run time was 10 min.

Quality assurance and data analysis

Quantification was performed using the internal standard method. A 10-point standard calibration curve was constructed using serial dilutions from 0.02 to 50 µg/L and fitted with a 1/x2 weighted regression. Perfluoro-1-[1,2,3,4-13C4] octanesulfonate and perfluoro-n-[1,2,3,4-13C4] octanoic acid were used as internal standards. The correlation coefficient was >0.99 for each analyte. The instrument detection limits (IDLs) and the limits of detection (LODs) were determined on the basis of a signal-to-noise ratio of three (S/N = 3) and were in the range of 0.002 to 0.04 µg/L and 0.002 to 0.08 ng/g, respectively (as shown in Supplemental Data, Table S2). The limits of quantification were defined as three times the LOD value. The recovery test was conducted by spiking standards mixture (2 ng) and internal standard (2 ng) into the analyzed samples (muscle, blood, liver, eggs, and brain sample) before extraction. The recoveries of spiked PFCs were in the range of 55 to 121%, except for perfluorotetradecanoic acid (28–71%). The details are shown in Supplemental Data, Table S2. The standard calibration was conducted before analysis, and mixed standard at 2 ng was run as the quality-control concentration, which was measured after every 10 injections to check for the stability of analysis and verify the calibration. If the standards were not within ± 20% of their initial values, a new calibration curve was performed.

To minimize background contamination, all potential sources of instrumental and procedural contamination were eliminated. Polytetrafluorethylene materials were removed from the laboratory equipment. All containers employed during the sample preparation and analysis procedures were washed thoroughly with methanol prior to use. One method blank sample was analyzed with every batch of eight samples.

Data were analyzed by SPSS 13.0 (SPSS Inc.). The Kruskal–Wallis H test was applied to examine species differences in PFC concentrations, with the significance set at the 0.05 level. Spearman's correlation analysis was used to investigate the relationships among different fish tissues for PFOS levels. In the statistical analysis, the levels were treated as zero if the compounds were below LOD in samples.

RESULTS AND DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS AND DISCUSSION
  6. SUPPLEMENTAL DATA
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

Perfluorinated compound concentrations in different fishes

The observed levels of PFCs in fish blood, liver, muscle, brain, and eggs from six fish species are presented in Supplemental Data, Table S3. In the present study, among the 14 PFCs, including 11 perfluorinated acids, two fluorotelomer acids, and perfluoro-1-octanesulfonamide, all PFCs except two fluorotelomer acids were detected. For all six fish species, at least 10 PFCs were detected in blood and different tissues, except in eggs, in which only five PFCs were detected. Perfluorooctane sulfonate was the predominant compound and was detected in all samples, ranging from 0.0260 ng/g wet weight in grass carp to 70.7 ng/g wet weight in bighead. For the six fish species, PFOS levels contributed to more than 50% of the total PFC in almost all blood samples and other tissues. However, this was not observed in the blood, muscle, and brain of tilapia or snakehead, in which PFOS accounted for 29.9 to 46.0% of the total PFC (Fig. 1). Significant differences in PFOS concentrations of blood and different tissues were found among the six fish species (p < 0.05). The observed PFOS mean (or median) concentrations (in ng/g wet wt) in blood and different tissues of bighead ranged from 1.48 to 22.5 (0.704–12.2), which were the highest levels among the six fish species. These concentrations were five- to 20-fold higher than in tilapia, in which the lowest PFOS mean (or median) concentrations (0.265–1.63 ng/g wet wt [0.113–1.42]) were found, and 2- to 10-fold higher compared with the other fish species. For snakehead, grass carp, common carp, and crucian carp, the ranges of PFOS mean (or median) concentrations were 0.412 to 6.99 (0.236–4.23), 0.473 to 5.77 (0.350–2.40), 0.456 to 3.36 (0.319–2.82), and 0.735–6.34 (0.552 to 4.41), respectively. Meng et al. 26 showed that contaminant concentrations may be different between carnivorous and omnivorous fish because of the use of different fish feeds. Van Leeuwen et al. 27 also indicated that contaminant concentrations may be low in tilapia because of their diet, which consists predominantly of proteins and lipids from vegetable sources. This may be a reason why tilapia exhibited the lowest PFOS concentration among the six fish species in the present study. Eggs were collected from snakehead (n = 4), crucian carp (n = 12), and common carp (n = 2), and their mean PFOS concentrations were 1.72 ng/g wet weight, 5.07 ng/g wet weight, and 1.64 ng/g wet weight, respectively.

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Figure 1. Composition profiles of 12 perfluorinated compounds detected in blood and different fish tissues.PFTrDA = perfluorotridecanoic acid; PFBS = nonafluorobutane-1-sulfonic acid; FOSA = perfluoro-1-octanesulfonamide; PFTA = perfluorotetradecanoic acid; PFDoDA = perfluorododecanoic acid; PFNA = perfluorononanoic acid; PFOA = perfluorooctanoic acid; PFHpA = perfluoroheptanoic acid; PFHxS = perfluorohexane sulfonate; PFDA = perfluorodecanoic acid; PFUnDA = perfluoroundecanoic acid; PFOS = perfluorooctane sulfonate.

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For all six fish species, PFUnDA, ranging from <LOD to 19.2 ng/g wet weight, was the second dominant PFC in blood, liver, muscle, and eggs. However, the levels of PFDA in brain (<LOD–0.963ng/g wet wt) were similar to or slightly higher than PFUnDA (<LOD–0.918ng/g wet wt), accounting for 7 to 26% of the total PFC. This could indicate that PFDA can cross the blood–brain barrier, which has been previously described in an article by Ylinen and Auriola 28. Unlike PFOS, the highest mean (or median) PFUnDA concentrations were found in blood and different tissues of snakehead, ranging from 0.235 to 4.80 ng/g wet weight (0.0775–2.37 ng/g wet wt). The lowest levels of PFUnDA were found in common carp, ranging from 0.0711 to 0.853 ng/g wet weight (<LOD–0.693 ng/g wet wt). However, levels of PFUnDA in blood and different tissues among the different six species were not significant (p > 0.05). In comparison, low levels of PFOA (mean range, <LOD–0.618 ng/g wet wt) were found in all six fish species.

Although little information is available on PFC levels in farmed freshwater fish, several studies have been performed to assess PFC levels in various wild fish. A comparison of the results from different studies is summarized in Table 1. For example, Li et al. 29 measured PFC concentrations in the blood of five fish species collected from Gaobeidian Lake, for which water comes mainly from the Gaobeidian wastewater treatment plant in Beijing. They observed that PFOS was the most abundant component in serum, with mean concentrations ranging from 5.74 to 64.2 ng/ml, which was higher than the concentrations found in the present study (1.15–22.5 ng/g wet wt). The mean PFOS and total PFC levels in the present study were also consistent with Li et al.'s 29 study, which found the highest levels in crucian carp followed by common carp and tilapia. Gulkowska et al. 20 reported PFOS levels in the muscle of different marine fish collected from Guangzhou and Zhoushan, China, with mean concentrations of 0.67 to 2.93 and 0.38 to 1.77 ng/g wet weight, respectively. In the United States, 10 PFC analytes were determined in fish samples collected from Minnesota lakes and rivers 18. Perfluorooctane sulfonate was the most commonly detected PFC, ranging from <1 to 2,000 ng/g. In another previously reported study involving the analysis of 60 whole-fish homogenates from the Ohio, Missouri, and Upper Mississippi Rivers (USA), PFOS contributed to more than 80% of the total PFC composition in fish, with mean (median) PFOS concentrations of 84.7 (24.4), 147 (31.8), and 93.1 (53.9) ng/g wet weight, respectively 30. Berger et al. 13 also reported that PFOS was the predominant PFC in edible fish from Lake Vättern in Sweden (medians 2.86–11.3 ng/g wet wt) and the Baltic Sea (medians 0.98–2.51 ng/g wet wt). Schuetze et al. 19 also investigated the levels of PFOS and PFOA in wild fish from northern Germany. They observed that PFOA was not found in any of the investigated samples above 0.27 ng/g wet weight, whereas PFOS was detected with concentrations up to 225 ng/g wet weight. Becker et al. 5 also detected PFOS levels in chub (mean range 13–123 ng/g wet wt) and river goby (mean range 80–295 ng/g wet wt), but PFOA was either low or not detected from the Roter Main River in Bayreuth, Germany. The reported PFOS concentrations in the present study were lower than those detected in the aforementioned studies, indicating that farmed fish were exposed to lower levels of PFC than wild fish.

Table 1. Comparison of perfluorooctane sulfonate (PFOS) levels (ng/g wet wt) in fish from different countries
LocationConcentrationsaFish tissueFish speciesReference
  • a

    Mean (median) values.

  • b

    Nanograms per milliliter.

  • c

    Range of concentrations.

    ND = Not detected.

Gaobeidian Lake, China9.88bSerumWhite semiknife carp29
 5.74bSerumTilapia 
 12.9bSerumLeather catfish 
 32.2bSerumCommon carp 
 64.2bSerumCrucian carp 
Minnesota lakes and rivers, USA<1–2,000cFilletDifferent fish species18
Ohio River, USA84.7 (24.4)Whole fishDifferent fish species30
Mississippi River, USA83.1 (53.9)Whole fishDifferent fish species 
Ohio River, USA147 (31.8)Whole fishDifferent fish species 
Northern GermanyND–225cMuscleDifferent fish species19
Roter Main River, Bayreuth, Germany123LiverChub5
 103KidneyChub 
 60GonadChub 
 57HeartChub 
 13MuscleChub 
 295OrganRiver goby 
 80MuscleRiver goby 
Guangzhou, China2.93MuscleSmall yellow croaker20
 0.67MuscleSilvery pomfret 
 0.91MuscleBelt fish 
 2.18MuscleJapanese mackerel 
Zhoushan, China0.92MuscleSmall yellow croaker20
 0.38MuscleSilvery pomfret 
 0.86MuscleWhite mouth croaker 
 1.77MuscleConger pike 
Lake Vättern, Sweden(11.3)MusclePerch13
 (12.0)MuscleBurbot 
 (2.86)MuscleWhitefish 
 (8.49)MuscleSalmon 
 (5.73)MuscleBrown trout 
Baltic Sea, Sweden(2.13)MusclePerch13
 (1.69)MuscleBurbot 
 (2.51)MuscleWhitefish 
 (0.98)MuscleSalmon 
 (1.08)MuscleBrown trout 

Tissue distribution of PFCs

Previous studies on fish have focused mostly on PFC levels in blood, muscle, or whole-body homogenates. However, little is known regarding the tissue distribution of PFCs in fish, particularly in farmed freshwater fish. To address this issue, we investigated the distribution ratios of PFOS and total PFC in blood and different tissues. Overall, the mean concentrations of PFOS and total PFC were the highest in fish blood (1.15–22.5 ng/g wet wt, 6.16–31.4 ng/g wet wt, respectively), followed by liver (1.63–14.1 ng/g wet wt, 2.54–16.9 ng/g wet wt, respectively), brain (0.512–5.51 ng/g wet wt, 0.991–6.34 ng/g wet wt, respectively), and muscle (0.265–1.48 ng/g wet wt, 0.689–2.04 ng/g wet wt, respectively). In tilapia, PFOS levels were higher in the liver than in the blood (Fig. 2). The comparison of PFOS and total PFC levels among the five different tissues and the finding that they were distributed primarily in blood confirms the premise that there may be a different extent of binding for different tissues; that is, PFCs bind more strongly to serum proteins than to fatty tissue 31. Because blood is a circulatory fluid, we evaluated the correlation between PFOS levels in blood and the different tissues among the five species. As shown in Supplemental Data, Table S4, we observed a significant correlation of PFOS levels between blood and the different tissues in bighead, snakehead, and grass carp (p < 0.01). For crucian and common carp, significant correlation was observed between PFOS levels in blood and in liver and brain (p < 0.01). However, PFOS levels in blood did not correlate with any tissues in tilapia (p > 0.01).

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Figure 2. Box-and-whisker plots of perfluorooctane sulfonate (PFOS) in six species of fish (ng/g wet wt). The horizontal black line in the box represents the median value, and the lower and upper edges of the box mark the 25th and 75th percentiles. The whiskers extending from the box show the highest and lowest values. Asterisks represent extreme values, which were beyond three times the difference between 25th and 75th percentiles, and singular values that were beyond the 150th percentile of the difference between 25th and 75th percentiles are represented by circles.

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To evaluate the accumulation of PFCs in liver, we calculated the liver-to-muscle concentration ratios for PFOS, PFOA, PFDA, and PFUnDA based on individual fish and compared them with previously reported results. In the present study, the mean ratios of liver to muscle for PFOS were 6.6, 16, 3.7, 6.5, 18, and 11 in grass carp, snakehead, crucian carp, common carp, tilapia, and bighead, respectively, which were generally lower than those in Chinese sturgeon (61.5 for PFOS) as reported by Peng et al. 32. A recent study also evaluated the contamination levels of PFOS and PFOA in edible fish from the Mediterranean Sea, in which the ratio of muscle:liver for PFOS was approximately 1:10 17. This observation was similar to the present study for grass carp, common carp, and bighead. The present study was also consistent with the results from investigations of PFOS in chub from the Roter Main River in Bayreuth, Germany 5, in which the mean PFOS levels in liver and muscle were 123 ± 15 ng/g wet weight and 13 ± 3 ng/g wet weight, respectively. The mean ratios of liver to muscle for PFOA (1.22–3.99), PFDA (2.90–9.77), and PFUnDA (2.62–10.26) in the present study were found to be lower than for PFOS. This indicated that PFOS has a stronger potential accumulation than perfluorinated carboxylic acids. The ratios of liver to muscle for PFUnDA in Chinese sturgeon (63.4) 32 and common guillemot (19.0) 33 were both much higher than our observed levels (2.62–10.26). We also observed a higher accumulation of perfluorinated carboxylic acids with longer carbon chains. A similar trend was also reported by Martin et al. 34, indicating that perfluorinated carboxylic acids with longer chains might have higher accumulation potential in biotic organisms. More research is needed to investigate this trend further.

In the present study, eggs were collected from three fish species: snakehead (n = 4), crucian carp (n = 12), and common carp (n = 2). Among these fish, the mean levels of PFOS in eggs (1.64–5.07 ng/g wet wt) were the second highest, lower than those in corresponding liver samples. Consistently, a previous study also demonstrated that the greatest total concentrations of PFCs and PFOS were both found in the female eggs of Chinese sturgeons 32, in which PFC levels were reported in different organs, including liver, muscle, eggs, and other organs (heart, ovary, stomach intestine, gill, kidney, and gallbladder) not included in the present study. A previous study also showed that liver accumulation of PFOS in birds might be transferred from the mother to the eggs along with yolk proteins as a protein–PFOS complex 33. Therefore, the ratio of PFOS concentrations in eggs to liver is often used to evaluate maternal transfer. We calculated these ratios in snakehead, common carp, and crucian carp, the means of which were 0.93, 1.4, and 2.0, respectively. In a recent study, Peng et al. 32 calculated that the eggs-to-liver ratio of PFOS for Chinese sturgeon was 1.9. This ratio was similar to that in crucian carp and higher than that in snakehead and common carp reported in the present study. Another study on the tissue distribution of PFCs in common guillemot 33 showed that the eggs-to-liver ratio of PFOS was approximately 3.0, which was higher than our reported value. The dissimilarities in eggs-to-liver ratios of PFOS might indicate that the maternal transfer is different among fish species or animals.

Dietary intake of PFCs through fish consumption

Some studies have suggested that fish intake is an important factor for human exposure to PFCs 12, 13, 19, 35–37. Fromme et al. 37 showed that consumption of highly contaminated fish may increase PFC levels in the body. Therefore, the results from the present study could be used to provide a preliminary estimate of the dietary intake of PFOS and total PFC through fish consumption, expressed as nanograms per kilogram body weight per day for an adult with 60 kg body weight. In a recent report, the relative contributions of major food categories to food composition were described, showing that the consumption of freshwater fish (common carp, grass carp, crucian carp, and bighead) in Beijing was 0.49 ± 0.48 g/kg body weight/d and consumption of individual fish species was 0.11 ± 0.15, 0.10 ± 0.16, 0.22 ± 0.28, and 0.059 ± 0.12 g/kg body weight/d, respectively 38. Based on this, the dietary intake for both PFOS and total PFC was calculated (dietary intake = PFC concentration × fish consumption [g/kg body weight/d]). With the assumption that fish muscle is the only consumed tissue (the values below LOD were set as zero), the mean dietary intake of PFOS and total PFC through total fish consumption was 0.24 and 0.45 ng/kg body weight/d, respectively. The mean dietary intake of PFOS (total PFC) through common carp, grass carp, crucial carp, and bighead was 0.050 (0.079), 0.047 (0.076), 0.16 (0.26), and 0.088 (0.12), respectively. In a previous study, seven types of seafood collected from fish markets in two coastal cities of China were analyzed for nine PFCs 20. The dietary intake of PFOS through fish consumption was 1.7 to 2.8 ng/kg body weight/d, which is much higher than our reported levels. In Sweden, PFCs were evaluated in muscle tissue from edible fish species collected in the second largest freshwater lake, Lake Vättern, and in the brackish water of Baltic Sea 13. Median PFOS intakes were estimated at 0.15 and 0.62 ng/kg/d for moderate and high consumers of Baltic Sea fish, respectively, which were similar to our reported values. However, the calculated median PFOS intake of groups consuming high amounts of Lake Vättern fish was 2.7 ng/kg/d, which was higher than ours. In the present study, the dietary intake of PFC would increase when the consumption of other fish tissues was taken into account. Although there is no uniform tolerable daily intake level, at which no appreciable health risks would be expected over a lifetime, established for PFOS, the United Kingdom Food Standards Agency Committee on Toxicology has established provisional tolerable daily intake levels of 300 and 3,000 ng/kg/d for PFOS and PFOA, respectively 39 (http://www.food.gov.uk/science/surveillance/fsisbranch2006/fsis1106). Furthermore, the European Food Safety Authority has also derived a tolerable daily intake of 150 ng/kg/d for PFOS and 1,500 ng/kg/d for PFOA 40. Thus, for the population of Beijing, the dietary intake of PFC via fish consumption is far below the recommended values, indicating that there is a low potential exposure risk to PFCs by consumption of farmed freshwater fish. However, further studies are needed to investigate the source of PFCs in these fish.

Acknowledgements

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS AND DISCUSSION
  6. SUPPLEMENTAL DATA
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

The present study was jointly supported by the National Natural Science Foundation of China (20837003, 20907063, 20890111), the National Basic Research Program of China (2009CB421605), and the State Environmental Protection Welfare Scientific Research Project (201009026).

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS AND DISCUSSION
  6. SUPPLEMENTAL DATA
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information
  • 1
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    Roos PH, Angerer J, Dieter H, Wilhelm M, Wolfle D, Hengstler JG. 2008. Perfluorinated compounds (PFC) hit the headlines. Arch Toxicol 82: 5759.
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Supporting Information

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS AND DISCUSSION
  6. SUPPLEMENTAL DATA
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

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