Environ Sci Pollut Res (2015) 22:1480–1486 DOI 10.1007/s11356-014-3439-x
RESEARCH ARTICLE
Factors affecting the accumulation of perfluoroalkyl substances in human blood Cristian Gómez-Canela & María Fernández-Sanjuan & Mireia Farrés & Silvia Lacorte
Received: 7 June 2014 / Accepted: 10 August 2014 / Published online: 28 August 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract The aim of this study is to evaluate the presence of perfluoroalkyl substances (PFASs) in the blood of 46 residents from Barcelona and to study the factors that affect exposure. Compounds analysed included perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorobutane sulfonate (PFBS), perfluorooctanoate acid (PFOA) and perfluorononanoate acid (PFNA). Blood was liquid–liquid extracted and PFASs were determined by liquid chromatography coupled to tandem mass spectrometry. Good recoveries (between 97±14 and 105±13 %) were obtained and method detection limits were from 0.03 to 0.07 ng mL−1. ΣPFASs ranged from 0.11 to 4.37 ng mL−1. PFOS was the main compound detected at 0.09–3.35 ng mL −1 , followed by PFOA and PFHxS. PFBS and PFNA were seldom detected. Working conditions, smoking and gender did not cause any significant differences among ΣPFASs levels in the blood while age and parity produced decreased concentrations. On the other hand, laboratory working conditions produced significant higher PFOA levels compared to the general population. Compared to other studies, the PFASs levels in blood from Barcelona residents is low (mean ΣPFASs of 1.67 ± 0.88 ng mL−1) and with little variation among the studied population.
Keywords Perfluoroalkyl substances . Human blood . Exposure . LC-MS/MS Responsible editor: Philippe Garrigues C. Gómez-Canela : M. Fernández-Sanjuan : M. Farrés : S. Lacorte (*) Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain e-mail: [email protected]
Introduction Perfluoroalkyl substances (PFASs) have aroused interest because they have become widespread contaminants with bioaccumulative properties as a result of their extensive use in industrial and household products. In humans, diet (Cherrie et al. 2006), breathing (Ji et al. 2012) and long or acute environmental exposure periods contribute to the accumulation of PFASs. Once uptaken, PFASs can be excreted (Cui et al. 2010) or accumulated in different tissues (Fromme et al. 2009; Wilhelm et al. 2009). Blood, serum or plasma have been identified as excellent monitoring matrices to assess the presence of PFASs in humans (Ericson et al. 2007). The worldwide impact of PFASs in humans is reflected in various studies. Perfluorooctane sulfonate (PFOS) was the main compound detected in whole blood samples from Chinese residents at levels from 0.43 to 59.1 ng mL − 1 and perfluorooctanoic acid (PFOA) varied from 0.33 to 7.98 ng mL−1 (Guo et al. 2011) and different human exposure sources and pathways of PFASs explained the varying concentrations. PFOS also accounted for the highest detected compound in whole blood from residents from nine provinces of China with concentrations between 3.06 and 34 ng mL−1, followed by PFOA (0.26–1.88 ng mL−1) (Pan et al. 2010). In another study, differences of PFASs in human blood in citizens from various locations in China were attributed to fish consumption (Zhang et al. 2011a). However, the highest levels reported in China are related to occupational exposure to PFASs, where high PFOS (from 0.05 to 31.6 ng mL−1) and PFOA (from 0.17 to 117 ng mL−1) levels were detected in serum from workers of a leather factory in Wenzhou city, which is characterized as the ‘Footwear Capital’ of China (Zhang et al. 2011b). Lien et al. analysed umbilical cord plasma samples from inhabitants in Taiwan and PFOS was detected in 98 % of the samples at a median concentration of 5.67 ng mL−1, followed by PFOA and perfluorononanoic acid
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(PFNA) which were detected at median concentrations of 4.42 and 10.5 ng mL−1, respectively (Lien et al. 2011). In Norway, PFASs were detected in 90 % of the plasma samples with mean concentrations of 20 ng mL−1 for PFOS and 0.81 ng mL−1 for PFNA, the least detected compound, and fish and shellfish consumption contributed to their accumulation in humans (Rylander et al. 2010). Plasma samples from the adult population of Germany contained PFOS and PFOA at median concentrations of 10.9 and 4.8 ng mL−1, respectively, in females and of 13.7 and 5.7 ng mL−1, respectively, in males, being the differences significant between genders (Fromme et al. 2007). Among these studies, it is observed that the impact of PFASs is geographically dependent and that diet or direct exposure of contaminants through working place or working habits are the main causes of accumulation in humans (Herzke et al. 2013; Lü et al. 2014). Exposure to PFASs can lead to sanitary and health problems related to neurotoxicity, tiredness, apathy, asthenia, thyroid disruption and even cancer. A recent study has shown that PFASs in serum can represent a risk factor in the development of breast cancer as median PFOS levels in serum were of 45.6 ng mL−1 in breast cancer patients and 21.9 ng mL−1 in control samples from Greenland residents (Bonefeld-Jorgensen et al. 2011). Still, there is little information on the factors that affect the accumulation of PFASs in humans. Therefore, the aim of the present study was to evaluate the effect of workplace, age, gender, smoking habits and parity on the accumulation of five PFASs in the blood of 46 residents from Barcelona. Emphasis was given to study the exposure of PFASs in laboratory workers from the Department of Environmental Chemistry in Barcelona via use and manipulation of PFASs-containing products and samples.
Experimental Chemicals and reagents Native compounds of PFOS, perfluorohexane sulfonate (PFHxS), perfluorobutane sulfonate (PFBS), PFOA and PFNA were supplied by Wellington Laboratories (Ontario, Canada). Stock standard solutions were prepared in acetonitrile at a concentration of 5 ng μL−1 for all native compounds and were stored at −18 °C. Perfluoron-(1,2,3,4-13C4) octanoic acid (MPFOA) and sodium perfluoro-1-(1,2,3,4-13C4) octanesulfonate (MPFOS), also from Wellington Laboratories, were used as surrogate standards. HPLC grade water and acetonitrile were supplied by Merck (Darmstadt, Germany) and glacial acetic acid from Panreac (Barcelona, Spain).
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Sampling Forty-six blood samples from healthy adults were collected from Barcelona residents (Catalonia, Spain). Age, gender, profession at sampling period, smoking and parity were recorded (Table 1). Samples analysed corresponded to 19 women and 11 men, with ages comprised from 19 to 53 years. Of all the samples analysed, 16 corresponded to scientists or technicians working in the Department of Environmental Chemistry in IDAEA-CSIC (Barcelona) dealing with the analysis of PFASs or exposed through air. The rest of the samples (n=30) corresponded to the general population and professions are indicated in Table 1. Blood samples of about 3 mL were collect from each participant by venepuncture between November 2009 and February 2010 and kept into polypropylene tubes with heparin and frozen at −20 °C until analysed. Donation was performed in the morning before breakfast. PFASs extraction, clean-up and instrumental analysis Five hundred microlitres of blood were spiked with 10 ng of internal standards (MPFOS and MPFOA) and the sample was incubated for 18 h at 4 °C. Nine mL of acetonitrile were added and PFASs were liquid–liquid extracted in an ultrasonic bath for 10 min at room temperature (three times). Then, the samples were centrifuged at 2,500 rpm for 5 min. The supernatant was transferred to a new vial and evaporated to dryness, reconstituted with 1 mL of acetonitrile and incubated for 10 min in the ultrasonic bath. The clean-up consisted in adding 25 mg of activated carbon and 50 μL of glacial acetic acid and the solution was mixed vigorously for 1 min (Gómez-Canela et al. 2012). Afterwards, the samples were centrifuged for 10 min at 10,000 rpm and the supernatant was filtered through GHP Acrodisc® 0.2 μm (13-mm filter) to eliminate residual carbon particles, transferred to a clean micro vial, evaporated and reconstituted with 500 μL of 70:30 acetonitrile/water. PFASs were measured using an ACQUITY ultra performance liquid chromatography system connected to a triple quadruple detector (Waters, USA) (LC-MS/MS). The analysis was performed on a LiChroCART HPLC RP-18e column (125 mm×2 mm, 5-μm particle size, Merck, Germany). Separation and detection method parameters were as reported in previous studies (Fernandez-Sanjuan et al. 2010; Gómez et al. 2011). The PFASs were measured under negative electrospray ionisation and acquisition was performed in selected reaction monitoring (SRM) using one or two transitions from parent to product ion to identify each compound. Samples were extracted and analysed in batches together with a procedural blank to control any external contamination during the whole analytical process. Internal standard quantification was performed using MPFOS to quantify PFOS, PFHxS and PFBS and
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Table 1 Concentration of PFCs (ng mL−1) in blood, ordered by females (F) and males (M) and age of donors. Profession, smoking habits and children (only females) are recorded (Y=yes, N=no). In italics, laboratory-exposed population ID
Age (year)
Profession
Smoker
Children
PFOS
PFHxS
PFBS
PFOA
PFNA
ΣPFCs
F1 F2 F3 F4
21 25 26 26
Technician Student Researcher Researcher
Y Y Y Y
N Y N N
0.32 0.29 2.02 1.36
0.57 N.D. 0.16 0.28
N.D. N.D. N.D. N.D.
0.15 0.26 0.72 0.62
N.D. N.D. 0.10 0.11
1.04 0.55 3.00 2.37
F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22
28 28 28 29 29 29 32 33 37 40 40 41 43 44 44 45 47 49
Nurse Researcher Researcher Nurse Dentist Nurse Housewife Researcher Administrative Administrative Administrative Hairdresser Nurse Researcher Nurse Saleswoman Cleaner Housewife
N N EX Y N Y N Y N N EX N N N EX EX N N
N N N N N Y Y N Y Y Y Y Y Y Y Y Y Y
0.11 2.49 0.61 1.40 2.60 1.00 0.31 0.19 1.39 0.32 0.49 0.40 0.19 0.13 0.77 0.33 0.21 0.23
N.D. N.D. N.D. N.D. N.D. N.D. 0.68 0.47 0.13 0.11 0.46 0.56 0.11 0.16 0.23 0.87 0.27 0.44
N.D. 0.43 N.D. N.D. N.D. N.D. 0.31 N.D. 0.19 N.D. N.D. N.D. 0.18 N.D. 0.30 N.D. N.D. 0.20
N.D. 0.69 0.52 0.20 0.21 0.25 0.09 1.08 0.29 0.66 0.27 0.07 0.72 0.35 0.33 0.49 0.27 0.34
N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. 0.10 N.D. 0.06 N.D. N.D. N.D. 0.19 N.D. 0.08
0.11 3.61 1.12 1.60 2.81 1.25 1.39 1.74 2.00 1.19 1.22 1.09 1.20 0.64 1.63 1.88 0.75 1.29
F23 F24 F25 F26 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13 M14 M15
49 51 52 52 19 20 23 24 25 25 35 36 36 39 40 41 44 46 47
Caregiver Administrative Supermarket cashier Nurse Technician Technician Technician Researcher Technician Researcher Spring manufacturer Computer Researcher Researcher Salesman Truck driver Administrative Car tester Retired
Y N N N N N Y N Y N Y N N N N N Y N EX
Y Y Y Y – – – – – – – – – – – – – – –
0.27 0.27 0.78 0.44 0.70 0.58 1.00 3.35 0.43 0.48 0.59 0.79 0.11 1.34 1.13 0.19 0.09 1.41 0.95
0.64 0.62 0.29 0.59 0.10 N.D. 0.21 N.D. 0.13 0.21 0.47 N.D. 0.54 N.D. 0.28 0.15 0.09 0.25 0.5
0.16 0.25 0.30 N.D. 0.17 N.D. N.D. N.D. 0.10 0.30 N.D. 0.04 N.D. N.D. N.D. N.D. N.D. 0.06 N.D.
0.78 0.32 1.03 0.27 0.46 0.34 0.27 1.02 0.22 0.72 0.48 0.30 0.56 0.79 0.73 0.50 0.16 0.50 0.52
0.35 N.D. N.D. N.D. 0.05 N.D. 0.12 N.D. N.D. N.D. N.D. 0.20 N.D. N.D. 0.09 2.94 N.D. 0.12 0.34
2.20 1.46 2.40 1.30 1.48 0.92 1.60 4.37 0.88 1.71 1.54 1.33 1.21 2.13 2.23 3.78 0.34 2.34 2.31
M16 M17 M18 M19 M20
49 49 49 52 53
Truck driver Truck driver Administrative Truck driver Researcher
EX EX EX Y N
– – – – –
1.27 0.57 0.24 0.62 0.67
0.9 0.16 0.09 0.25 N.D.
0.08 N.D. N.D. 0.08 N.D.
0.59 0.34 0.24 0.26 1.05
0.10 0.37 0.08 0.22 N.D.
2.94 1.44 0.65 1.43 1.72
EX ex-smoker; N.D. not detected
Environ Sci Pollut Res (2015) 22:1480–1486 Table 2 Quality parameters obtained by LC-MS/MS. Response factor, instrumental detection limit (IDL); methodological detection limit (MDL) and recoveries±relative standard deviation (%R±RSD)
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Target compounds
Response factor
IDL (pg)
MDL (ng mL−1)
% R±RSD, n=3
PFOS PFHS PFBS PFOA PFNA
0.956 0.475 1.000 0.574 0.750
1.4 1.1 0.7 1.8 1.9
0.07 0.07 0.04 0.03 0.05
97±14 100±14 103±15 105±13 103±11
MPFOA to quantify PFOA and PFNA. Five-point calibration curves were constructed over a concentration range of 1 to 50 ng mL−1. Recovery studies were performed using blood samples spiked with native compounds at 20 ng mL−1, concentration chosen according to the levels of PFASs in blood reported in the open bibliography. Recovery values ranged from 97 ± 14 % (PFOS) to 105 ± 13 % (PFOA) (Table 2), analysed from triplicate blood samples and where the initial concentration of PFASs was subtracted. Method detection limits (LODmethod) calculated using three times the signal-to-noise ratio (the ratio between the peak intensity and the noise measured 1 min after the peak signal) ranged from 0.03 to 0.07 ng mL−1.
Results and discussion Summary data Table 1 indicates the concentration of PFASs in each blood sample. ΣPFASs ranged from 0.11 to 4.37 ng mL−1. PFOS was detected in all samples with a mean concentration of 0.77 ±0.71 ng mL−1, followed by PFOA (0.45±0.27 ng mL−1, n= 45), PFHxS (0.26±0.22 ng mL−1, n=34), PFBS (0.20± 0.11 ng mL−1, n=16) and PFNA (0.12±0.43 ng mL−1, n= 18). The prevalence of PFOS in human blood was also observed in other studies (Kärrman et al. 2007; Zhang et al. 2013). The concentrations obtained herein are slightly lower than early studies carried out in blood from 48 residents from Tarragona (south Catalonia, Spain) analysed in 2006 where PFOS, PFHxS and PFOA were detected at mean levels of 7.64, 3.56 and 1.80 ng mL−1, respectively (Ericson et al. 2007). However, PFASs levels are highly variable according to the study population and it is apparent that PFASs are widespread in all blood/serum samples worldwide. In a recent study, Vassiliadou et al. analysed 182 serum samples and did not find significant differences between residents from Athens (n=56), rural sites (n=86) and cancer patients (n=40). In that study, PFOS mean levels ranged from 7.49 to 14.93 ng mL−1 and PFOA mean levels ranged from 1.95 to 3.88 ng mL−1 (Vassiliadou et al. 2010). Somewhat lower levels were
Statistical analysis One-way analysis of variance (ANOVA) considering significant p values of ≤0.05 was used to determine the differences among PFASs levels according to each parameter studied. The variables considered to influence the ΣPFASs or individual compounds levels in blood were smoking, gender, parity, PFASs exposure and age divided in four groups (19–29, 30–39, 40–49, >50). Values below detection limit were substituted with half of the LOD. All calculations were operated in MATLAB software version 7.4. 3.5
Fig. 1 Bar chart of mean ∑PFASs ± standard deviation (ng mL−1) and differences among factors studied
smoking
parity
sex
exposure
3
mean Σ PFAs (ng mL-1 )
2.5
2
1.5
1
0.5
0 smokers
non-smokers
female
male
N= 13
N= 33
N= 26
N= 20
women without children N= 9
women with children N= 17
exposed
non-exposed
N= 16
N= 30
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Environ Sci Pollut Res (2015) 22:1480–1486 2
Fig. 2 Distribution of PFASs (ng mL−1) among different age groups
1.8
mean PFASs (ng mL-1)
1.6 1.4
PFNA
1.2
PFBS
1
PFHX
0.8
PFOA
0.6
PFOS
0.4 0.2 0 19-29
30-39
N= 16
N= 7
reported in 120 exposed residents living near fluorochemical plants in Fuxin, China, with mean concentrations of 8.2± 11 ng mL−1 (PFOA), 2.7 ± 4.6 ng mL−1 (PFOS), 1.3 ± 0.68 ng mL−1 (PFNA), 0.33±0.32 ng mL−1 (PFHxS) and 0.19±0.19 ng mL−1 (PFBS) (Bao et al. 2011). According to previous reported concentrations, the PFASs levels reported in residents from Barcelona are in the low range. Factors affecting the accumulation of PFASs in human blood PFASs accumulation in blood and compound specific profile depend on many factors, including direct or indirect exposure, food habits, age, parity, etc. However, it is not yet conclusive as to what are the sources of PFASs in humans and the factors that rule PFASs accumulation. Working conditions Out of 46 samples analysed and considering all the professions recorded, three scientists (3.00–4.37 ng mL−1), four truck drivers (2.94–3.78 ng mL −1), two sellers (1.88– 2.23 ng mL−1) and a dentist (2.81 ng mL−1) had the highest 2.5
[PFOS] (ng mL-1)
2
1.5
1
0.5
0
Women without children
Women with children
Fig. 3 Boxplot of PFOS concentration (in nanogrammes per millilitre) according to parity
age range
40-49
50-53
N= 18
N= 5
ΣPFASs levels in blood. The specific exposure route is not yet unrevealed, although the manipulation or contact with PFASs containing products can represent an important uptake pathway. A specific case of contaminant exposure is laboratory working conditions, where personnel can be exposed through manipulation and preparation of samples and standards or through indirect pathways such as air. Although working conditions must ensure minimal contact with chemicals, it is inevitable that the ambient air contains traces of PFASs or other contaminants. To explore whether laboratory workers might be exposed to PFASs, the first step was to evaluate the levels of PFASs in personnel from the Department of Environmental Chemistry (n=16), including technicians and researchers and to compare it with the general population (n= 30). Considering laboratory workers (n=16), PFOS was the main compound detected at 0.13–3.35 ng mL−1, followed by PFOA that ranged from 0.15 to 1.08 ng mL−1, and both compounds were detected in all samples analysed. PFHxS was detected in 10 samples out of 16 and ranged from 0.10 to 0.57 ng mL−1. PFBS and PFNA were only detected in four samples at 0.1 to 0.43 ng mL−1 and 0.05 to 0.12 ng mL−1, respectively. In the general population (n=30), PFOS ranged from 0.11 to 2.60 ng mL −1 and PFOA from 0.07 to 1.03 ng mL−1. PFHxS was detected in 24 samples out of 30 at 0.09 to 0.87 ng mL−1, PFBS was detected in 12 samples at 0.04 to 0.31 ng mL−1, and PFNA was detected in 14 samples at 0.06 to 2.94 ng mL−1. No significant differences were observed between laboratory workers and the general population, being the mean values of ΣPFASs 1.59 ± 0.59 ng mL−1 and 1.85±1.04 ng mL−1, respectively (Fig. 1). Considering individual compounds, PFOA levels differed significantly between laboratory workers and the rest of population (p=0.0062) whereas no differences were observed for the other compounds. According to these results, laboratory personnel from the Department of Environmental Chemistry could be affected by direct exposure to PFOA, although the specific sources of contamination should be further explored.
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Therefore, while working in the laboratory of the Department of Environmental Chemistry might have an influence on the accumulation of PFOA, other professions can also contribute to the accumulation of PFASs in humans as these compounds are present in many goods and consumer products. Age PFASs, in special PFOS, are bioaccumulative and therefore an increase of their concentrations in humans with age is expected. In humans, it has been suggested that 20 years is enough to accumulate PFOS and PFOA at nanogrammes per millilitre levels in blood (Kärrman et al. 2006). The age cohort studied ranged from 19 to 53 years. When dividing by age groups (Fig. 2), no significant differences were observed on the ΣPFASs levels. Contrarily to what was expected, the highest age group, corresponding to >50 years, did not have higher ΣPFASs levels than younger people (Fig. 2). However, when considering individual compounds, PFOS (p=0.0387) and PFHxS (p=0.0299) had significant differences between age groups. Levels of PFOS in the 19–29 age group were the highest and decreased gradually up to the 40–53 age group, indicating a specific high PFASs exposure of young people due to early exposure, compared to other age groups. Similar to our study, Ericson et al. (2007) analysed PFASs in 48 human blood and found that PFHxS levels were significantly higher (p < 0.05) in the group of 25 ± 5 years (4.65 ± 3.70 ng mL−1) compared to the 55±5 age group (2.48± 1.39 ng mL−1) (Ericson et al. 2007). Gender, parity and habits The mean level for ΣPFASs in males was 1.81±0.99 ng mL−1 (n=20) slightly higher than in females that was of 1.57± 0.80 ng mL−1 (n=26) (Table 1, Fig. 1). No significant differences were found among any PFASs levels considering gender (p>0.1114). However, Fromme et al. (2007) analysed 356 human plasma samples from an adult population in Germany. In females, the levels were from 2.5 to 30.7 ng mL−1 for PFOS and from 1.5 to 16.2 ng mL−1 for PFOA and in males, the levels were from 2.1 to 55 ng mL−1 for PFOS and from 0.5 to 19.1 ng mL−1 for PFOA and significant correlation between both PFOS and PFOA concentrations and gender was observed (Fromme et al. 2007). On the other hand, parity had an influence in PFASs levels. Figure 1 shows the mean levels of ΣPFASs in women without children and in primiparae/ multiparae mothers, the latter being slightly lower. PFASs levels in blood from females without children ranged from 0.11 to 3.61 ng mL − 1 while lower levels (0.55 to 2.20 ng mL−1) were detected in mothers. According to ANOVA (Fig. 3), PFOS showed significant differences between both groups (p=0.0065). However, it should be taken into account that women without children were almost in the
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age group of 19–29 (only one was 33) and most of the mothers were in elder groups. So, the significant difference of PFOS between women without children and mothers was also affected by differences between age groups. Transfer of PFASs to the foetus during pregnancy or during breastfeeding has been identified as a way of releasing PFASs from body burdens (Brantsæter et al. 2013; Porpora et al. 2013). Other factors affecting PFASs accumulation are specific habits such as diet or smoking. Samples analysed corresponded to people who live in Barcelona. In this area, dietary habits consist in white fish, meat (little pork), olive oil, fruits and vegetables. Thus, it is expected a typical Mediterranean diet, although specific dietary habits on the accumulation of PFASs, were not studied. As for smoking habits, no differences were observed between smokers and non-smokers (Fig. 1), although smoking is not known to influence PFOS and PFOA levels (Midasch et al. 2006).
Conclusions PFASs were detected in all 46 blood samples from residents of Barcelona at low concentration levels. Laboratory workers, dentists, truck drivers, and salesmen had higher PFASs than the mean, but only PFOA level was statistically different from laboratory workers than in the general population. Contrarily, age and parity produced a significant difference on the levels of PFASs in blood, with decreasing levels with age or parity. Because PFASs were detected in all samples, exposure is generalized to the overall population and given the potential toxicity of PFASs, it is important to minimize contact or manipulation of PFASs containing products to avoid longterm accumulation and potential health effects. Acknowledgements Montserrat March, the nurse from our institute is acknowledged for organising the extraction of blood from workers from the Department of Environmental Chemistry of IDAEA-CSIC. Our friends, Anna Daví and Patricia López, are acknowledged for the extraction of blood of the “general population”. All donors are deeply thanked for their contribution and interest in the study.
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Environ Sci Pollut Res (2015) 22:1480–1486 Kärrman A, Langlois I, Bv B, Lindström G, Oehme M (2007) Identification and pattern of perfluorooctane sulfonate (PFOS) isomers in human serum and plasma. Environ Int 33:782–788 Lien GW, Wen TW, Hsieh WS, Wu KY, Chen CY, Chen PC (2011) Analysis of perfluorinated chemicals in umbilical cord blood by ultra-high performance liquid chromatography/tandem mass spectrometry. J Chromatogr B Anal Technol Biomed Life Sci 879:641– 646 Lü H, Cai QY, Jones KC, Zeng QY, Katsoyiannis A (2014) Levels of organic pollutants in vegetables and human exposure through diet: a review. Crit Rev Environ Sci Technol 44:1–33 Midasch O, Schettgen T, Angerer J (2006) Pilot study on the perfluorooctanesulfonate and perfluorooctanoate exposure of the German general population. Int J Hyg Environ Health 209:489–496 Pan Y, Shi Y, Wang J, Cai Y, Wu Y (2010) Concentrations of perfluorinated compounds in human blood from twelve cities in China. Environ Toxicol Chem 29:2695–2701 Porpora MG, Lucchini R, Abballe A, Ingelido AM, Valentini S, Fuggetta E, Cardi V, Ticino A, Marra V, Fulgenzi AR, De Felip E (2013) Placental transfer of persistent organic pollutants: a preliminary study on mother-newborn pairs. Int J Environ Res Public Health 10:699–711 Rylander C, Sandanger TM, Frøyland L, Lund E (2010) Dietary patterns and plasma concentrations of perfluorinated compounds in 315 Norwegian women: the NOWAC postgenome study. Environ Sci Technol 44:5225–5232 Vassiliadou I, Costopoulou D, Ferderigou A, Leondiadis L (2010) Levels of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) in blood samples from different groups of adults living in Greece. Chemosphere 80:1199–1206 Wilhelm M, Angerer J, Fromme H, Hölzer J (2009) Contribution to the evaluation of reference values for PFOA and PFOS in plasma of children and adults from Germany. Int J Hyg Environ Health 212: 56–60 Zhang T, Sun H, Lin Y, Wang L, Zhang X, Liu Y, Geng X, Zhao L, Li F, Kannan K (2011a) Perfluorinated compounds in human blood, water, edible freshwater fish, and seafood in China: daily intake and regional differences in human exposures. J Agric Food Chem 59:11168–11176 Zhang W, Lin Z, Hu M, Wang X, Lian Q, Lin K, Dong Q, Huang C (2011b) Perfluorinated chemicals in blood of residents in Wenzhou, China. Ecotoxicol Environ Saf 74:1787–1793 Zhang Y, Beesoon S, Zhu L, Martin JW (2013) Isomers of perfluorooctanesulfonate and perfluorooctanoate and total perfluoroalkyl acids in human serum from two cities in North China. Environ Int 53:9–17
RESEARCH ARTICLE
Factors affecting the accumulation of perfluoroalkyl substances in human blood Cristian Gómez-Canela & María Fernández-Sanjuan & Mireia Farrés & Silvia Lacorte
Received: 7 June 2014 / Accepted: 10 August 2014 / Published online: 28 August 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract The aim of this study is to evaluate the presence of perfluoroalkyl substances (PFASs) in the blood of 46 residents from Barcelona and to study the factors that affect exposure. Compounds analysed included perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorobutane sulfonate (PFBS), perfluorooctanoate acid (PFOA) and perfluorononanoate acid (PFNA). Blood was liquid–liquid extracted and PFASs were determined by liquid chromatography coupled to tandem mass spectrometry. Good recoveries (between 97±14 and 105±13 %) were obtained and method detection limits were from 0.03 to 0.07 ng mL−1. ΣPFASs ranged from 0.11 to 4.37 ng mL−1. PFOS was the main compound detected at 0.09–3.35 ng mL −1 , followed by PFOA and PFHxS. PFBS and PFNA were seldom detected. Working conditions, smoking and gender did not cause any significant differences among ΣPFASs levels in the blood while age and parity produced decreased concentrations. On the other hand, laboratory working conditions produced significant higher PFOA levels compared to the general population. Compared to other studies, the PFASs levels in blood from Barcelona residents is low (mean ΣPFASs of 1.67 ± 0.88 ng mL−1) and with little variation among the studied population.
Keywords Perfluoroalkyl substances . Human blood . Exposure . LC-MS/MS Responsible editor: Philippe Garrigues C. Gómez-Canela : M. Fernández-Sanjuan : M. Farrés : S. Lacorte (*) Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain e-mail: [email protected]
Introduction Perfluoroalkyl substances (PFASs) have aroused interest because they have become widespread contaminants with bioaccumulative properties as a result of their extensive use in industrial and household products. In humans, diet (Cherrie et al. 2006), breathing (Ji et al. 2012) and long or acute environmental exposure periods contribute to the accumulation of PFASs. Once uptaken, PFASs can be excreted (Cui et al. 2010) or accumulated in different tissues (Fromme et al. 2009; Wilhelm et al. 2009). Blood, serum or plasma have been identified as excellent monitoring matrices to assess the presence of PFASs in humans (Ericson et al. 2007). The worldwide impact of PFASs in humans is reflected in various studies. Perfluorooctane sulfonate (PFOS) was the main compound detected in whole blood samples from Chinese residents at levels from 0.43 to 59.1 ng mL − 1 and perfluorooctanoic acid (PFOA) varied from 0.33 to 7.98 ng mL−1 (Guo et al. 2011) and different human exposure sources and pathways of PFASs explained the varying concentrations. PFOS also accounted for the highest detected compound in whole blood from residents from nine provinces of China with concentrations between 3.06 and 34 ng mL−1, followed by PFOA (0.26–1.88 ng mL−1) (Pan et al. 2010). In another study, differences of PFASs in human blood in citizens from various locations in China were attributed to fish consumption (Zhang et al. 2011a). However, the highest levels reported in China are related to occupational exposure to PFASs, where high PFOS (from 0.05 to 31.6 ng mL−1) and PFOA (from 0.17 to 117 ng mL−1) levels were detected in serum from workers of a leather factory in Wenzhou city, which is characterized as the ‘Footwear Capital’ of China (Zhang et al. 2011b). Lien et al. analysed umbilical cord plasma samples from inhabitants in Taiwan and PFOS was detected in 98 % of the samples at a median concentration of 5.67 ng mL−1, followed by PFOA and perfluorononanoic acid
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(PFNA) which were detected at median concentrations of 4.42 and 10.5 ng mL−1, respectively (Lien et al. 2011). In Norway, PFASs were detected in 90 % of the plasma samples with mean concentrations of 20 ng mL−1 for PFOS and 0.81 ng mL−1 for PFNA, the least detected compound, and fish and shellfish consumption contributed to their accumulation in humans (Rylander et al. 2010). Plasma samples from the adult population of Germany contained PFOS and PFOA at median concentrations of 10.9 and 4.8 ng mL−1, respectively, in females and of 13.7 and 5.7 ng mL−1, respectively, in males, being the differences significant between genders (Fromme et al. 2007). Among these studies, it is observed that the impact of PFASs is geographically dependent and that diet or direct exposure of contaminants through working place or working habits are the main causes of accumulation in humans (Herzke et al. 2013; Lü et al. 2014). Exposure to PFASs can lead to sanitary and health problems related to neurotoxicity, tiredness, apathy, asthenia, thyroid disruption and even cancer. A recent study has shown that PFASs in serum can represent a risk factor in the development of breast cancer as median PFOS levels in serum were of 45.6 ng mL−1 in breast cancer patients and 21.9 ng mL−1 in control samples from Greenland residents (Bonefeld-Jorgensen et al. 2011). Still, there is little information on the factors that affect the accumulation of PFASs in humans. Therefore, the aim of the present study was to evaluate the effect of workplace, age, gender, smoking habits and parity on the accumulation of five PFASs in the blood of 46 residents from Barcelona. Emphasis was given to study the exposure of PFASs in laboratory workers from the Department of Environmental Chemistry in Barcelona via use and manipulation of PFASs-containing products and samples.
Experimental Chemicals and reagents Native compounds of PFOS, perfluorohexane sulfonate (PFHxS), perfluorobutane sulfonate (PFBS), PFOA and PFNA were supplied by Wellington Laboratories (Ontario, Canada). Stock standard solutions were prepared in acetonitrile at a concentration of 5 ng μL−1 for all native compounds and were stored at −18 °C. Perfluoron-(1,2,3,4-13C4) octanoic acid (MPFOA) and sodium perfluoro-1-(1,2,3,4-13C4) octanesulfonate (MPFOS), also from Wellington Laboratories, were used as surrogate standards. HPLC grade water and acetonitrile were supplied by Merck (Darmstadt, Germany) and glacial acetic acid from Panreac (Barcelona, Spain).
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Sampling Forty-six blood samples from healthy adults were collected from Barcelona residents (Catalonia, Spain). Age, gender, profession at sampling period, smoking and parity were recorded (Table 1). Samples analysed corresponded to 19 women and 11 men, with ages comprised from 19 to 53 years. Of all the samples analysed, 16 corresponded to scientists or technicians working in the Department of Environmental Chemistry in IDAEA-CSIC (Barcelona) dealing with the analysis of PFASs or exposed through air. The rest of the samples (n=30) corresponded to the general population and professions are indicated in Table 1. Blood samples of about 3 mL were collect from each participant by venepuncture between November 2009 and February 2010 and kept into polypropylene tubes with heparin and frozen at −20 °C until analysed. Donation was performed in the morning before breakfast. PFASs extraction, clean-up and instrumental analysis Five hundred microlitres of blood were spiked with 10 ng of internal standards (MPFOS and MPFOA) and the sample was incubated for 18 h at 4 °C. Nine mL of acetonitrile were added and PFASs were liquid–liquid extracted in an ultrasonic bath for 10 min at room temperature (three times). Then, the samples were centrifuged at 2,500 rpm for 5 min. The supernatant was transferred to a new vial and evaporated to dryness, reconstituted with 1 mL of acetonitrile and incubated for 10 min in the ultrasonic bath. The clean-up consisted in adding 25 mg of activated carbon and 50 μL of glacial acetic acid and the solution was mixed vigorously for 1 min (Gómez-Canela et al. 2012). Afterwards, the samples were centrifuged for 10 min at 10,000 rpm and the supernatant was filtered through GHP Acrodisc® 0.2 μm (13-mm filter) to eliminate residual carbon particles, transferred to a clean micro vial, evaporated and reconstituted with 500 μL of 70:30 acetonitrile/water. PFASs were measured using an ACQUITY ultra performance liquid chromatography system connected to a triple quadruple detector (Waters, USA) (LC-MS/MS). The analysis was performed on a LiChroCART HPLC RP-18e column (125 mm×2 mm, 5-μm particle size, Merck, Germany). Separation and detection method parameters were as reported in previous studies (Fernandez-Sanjuan et al. 2010; Gómez et al. 2011). The PFASs were measured under negative electrospray ionisation and acquisition was performed in selected reaction monitoring (SRM) using one or two transitions from parent to product ion to identify each compound. Samples were extracted and analysed in batches together with a procedural blank to control any external contamination during the whole analytical process. Internal standard quantification was performed using MPFOS to quantify PFOS, PFHxS and PFBS and
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Table 1 Concentration of PFCs (ng mL−1) in blood, ordered by females (F) and males (M) and age of donors. Profession, smoking habits and children (only females) are recorded (Y=yes, N=no). In italics, laboratory-exposed population ID
Age (year)
Profession
Smoker
Children
PFOS
PFHxS
PFBS
PFOA
PFNA
ΣPFCs
F1 F2 F3 F4
21 25 26 26
Technician Student Researcher Researcher
Y Y Y Y
N Y N N
0.32 0.29 2.02 1.36
0.57 N.D. 0.16 0.28
N.D. N.D. N.D. N.D.
0.15 0.26 0.72 0.62
N.D. N.D. 0.10 0.11
1.04 0.55 3.00 2.37
F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22
28 28 28 29 29 29 32 33 37 40 40 41 43 44 44 45 47 49
Nurse Researcher Researcher Nurse Dentist Nurse Housewife Researcher Administrative Administrative Administrative Hairdresser Nurse Researcher Nurse Saleswoman Cleaner Housewife
N N EX Y N Y N Y N N EX N N N EX EX N N
N N N N N Y Y N Y Y Y Y Y Y Y Y Y Y
0.11 2.49 0.61 1.40 2.60 1.00 0.31 0.19 1.39 0.32 0.49 0.40 0.19 0.13 0.77 0.33 0.21 0.23
N.D. N.D. N.D. N.D. N.D. N.D. 0.68 0.47 0.13 0.11 0.46 0.56 0.11 0.16 0.23 0.87 0.27 0.44
N.D. 0.43 N.D. N.D. N.D. N.D. 0.31 N.D. 0.19 N.D. N.D. N.D. 0.18 N.D. 0.30 N.D. N.D. 0.20
N.D. 0.69 0.52 0.20 0.21 0.25 0.09 1.08 0.29 0.66 0.27 0.07 0.72 0.35 0.33 0.49 0.27 0.34
N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. 0.10 N.D. 0.06 N.D. N.D. N.D. 0.19 N.D. 0.08
0.11 3.61 1.12 1.60 2.81 1.25 1.39 1.74 2.00 1.19 1.22 1.09 1.20 0.64 1.63 1.88 0.75 1.29
F23 F24 F25 F26 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13 M14 M15
49 51 52 52 19 20 23 24 25 25 35 36 36 39 40 41 44 46 47
Caregiver Administrative Supermarket cashier Nurse Technician Technician Technician Researcher Technician Researcher Spring manufacturer Computer Researcher Researcher Salesman Truck driver Administrative Car tester Retired
Y N N N N N Y N Y N Y N N N N N Y N EX
Y Y Y Y – – – – – – – – – – – – – – –
0.27 0.27 0.78 0.44 0.70 0.58 1.00 3.35 0.43 0.48 0.59 0.79 0.11 1.34 1.13 0.19 0.09 1.41 0.95
0.64 0.62 0.29 0.59 0.10 N.D. 0.21 N.D. 0.13 0.21 0.47 N.D. 0.54 N.D. 0.28 0.15 0.09 0.25 0.5
0.16 0.25 0.30 N.D. 0.17 N.D. N.D. N.D. 0.10 0.30 N.D. 0.04 N.D. N.D. N.D. N.D. N.D. 0.06 N.D.
0.78 0.32 1.03 0.27 0.46 0.34 0.27 1.02 0.22 0.72 0.48 0.30 0.56 0.79 0.73 0.50 0.16 0.50 0.52
0.35 N.D. N.D. N.D. 0.05 N.D. 0.12 N.D. N.D. N.D. N.D. 0.20 N.D. N.D. 0.09 2.94 N.D. 0.12 0.34
2.20 1.46 2.40 1.30 1.48 0.92 1.60 4.37 0.88 1.71 1.54 1.33 1.21 2.13 2.23 3.78 0.34 2.34 2.31
M16 M17 M18 M19 M20
49 49 49 52 53
Truck driver Truck driver Administrative Truck driver Researcher
EX EX EX Y N
– – – – –
1.27 0.57 0.24 0.62 0.67
0.9 0.16 0.09 0.25 N.D.
0.08 N.D. N.D. 0.08 N.D.
0.59 0.34 0.24 0.26 1.05
0.10 0.37 0.08 0.22 N.D.
2.94 1.44 0.65 1.43 1.72
EX ex-smoker; N.D. not detected
Environ Sci Pollut Res (2015) 22:1480–1486 Table 2 Quality parameters obtained by LC-MS/MS. Response factor, instrumental detection limit (IDL); methodological detection limit (MDL) and recoveries±relative standard deviation (%R±RSD)
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Target compounds
Response factor
IDL (pg)
MDL (ng mL−1)
% R±RSD, n=3
PFOS PFHS PFBS PFOA PFNA
0.956 0.475 1.000 0.574 0.750
1.4 1.1 0.7 1.8 1.9
0.07 0.07 0.04 0.03 0.05
97±14 100±14 103±15 105±13 103±11
MPFOA to quantify PFOA and PFNA. Five-point calibration curves were constructed over a concentration range of 1 to 50 ng mL−1. Recovery studies were performed using blood samples spiked with native compounds at 20 ng mL−1, concentration chosen according to the levels of PFASs in blood reported in the open bibliography. Recovery values ranged from 97 ± 14 % (PFOS) to 105 ± 13 % (PFOA) (Table 2), analysed from triplicate blood samples and where the initial concentration of PFASs was subtracted. Method detection limits (LODmethod) calculated using three times the signal-to-noise ratio (the ratio between the peak intensity and the noise measured 1 min after the peak signal) ranged from 0.03 to 0.07 ng mL−1.
Results and discussion Summary data Table 1 indicates the concentration of PFASs in each blood sample. ΣPFASs ranged from 0.11 to 4.37 ng mL−1. PFOS was detected in all samples with a mean concentration of 0.77 ±0.71 ng mL−1, followed by PFOA (0.45±0.27 ng mL−1, n= 45), PFHxS (0.26±0.22 ng mL−1, n=34), PFBS (0.20± 0.11 ng mL−1, n=16) and PFNA (0.12±0.43 ng mL−1, n= 18). The prevalence of PFOS in human blood was also observed in other studies (Kärrman et al. 2007; Zhang et al. 2013). The concentrations obtained herein are slightly lower than early studies carried out in blood from 48 residents from Tarragona (south Catalonia, Spain) analysed in 2006 where PFOS, PFHxS and PFOA were detected at mean levels of 7.64, 3.56 and 1.80 ng mL−1, respectively (Ericson et al. 2007). However, PFASs levels are highly variable according to the study population and it is apparent that PFASs are widespread in all blood/serum samples worldwide. In a recent study, Vassiliadou et al. analysed 182 serum samples and did not find significant differences between residents from Athens (n=56), rural sites (n=86) and cancer patients (n=40). In that study, PFOS mean levels ranged from 7.49 to 14.93 ng mL−1 and PFOA mean levels ranged from 1.95 to 3.88 ng mL−1 (Vassiliadou et al. 2010). Somewhat lower levels were
Statistical analysis One-way analysis of variance (ANOVA) considering significant p values of ≤0.05 was used to determine the differences among PFASs levels according to each parameter studied. The variables considered to influence the ΣPFASs or individual compounds levels in blood were smoking, gender, parity, PFASs exposure and age divided in four groups (19–29, 30–39, 40–49, >50). Values below detection limit were substituted with half of the LOD. All calculations were operated in MATLAB software version 7.4. 3.5
Fig. 1 Bar chart of mean ∑PFASs ± standard deviation (ng mL−1) and differences among factors studied
smoking
parity
sex
exposure
3
mean Σ PFAs (ng mL-1 )
2.5
2
1.5
1
0.5
0 smokers
non-smokers
female
male
N= 13
N= 33
N= 26
N= 20
women without children N= 9
women with children N= 17
exposed
non-exposed
N= 16
N= 30
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Fig. 2 Distribution of PFASs (ng mL−1) among different age groups
1.8
mean PFASs (ng mL-1)
1.6 1.4
PFNA
1.2
PFBS
1
PFHX
0.8
PFOA
0.6
PFOS
0.4 0.2 0 19-29
30-39
N= 16
N= 7
reported in 120 exposed residents living near fluorochemical plants in Fuxin, China, with mean concentrations of 8.2± 11 ng mL−1 (PFOA), 2.7 ± 4.6 ng mL−1 (PFOS), 1.3 ± 0.68 ng mL−1 (PFNA), 0.33±0.32 ng mL−1 (PFHxS) and 0.19±0.19 ng mL−1 (PFBS) (Bao et al. 2011). According to previous reported concentrations, the PFASs levels reported in residents from Barcelona are in the low range. Factors affecting the accumulation of PFASs in human blood PFASs accumulation in blood and compound specific profile depend on many factors, including direct or indirect exposure, food habits, age, parity, etc. However, it is not yet conclusive as to what are the sources of PFASs in humans and the factors that rule PFASs accumulation. Working conditions Out of 46 samples analysed and considering all the professions recorded, three scientists (3.00–4.37 ng mL−1), four truck drivers (2.94–3.78 ng mL −1), two sellers (1.88– 2.23 ng mL−1) and a dentist (2.81 ng mL−1) had the highest 2.5
[PFOS] (ng mL-1)
2
1.5
1
0.5
0
Women without children
Women with children
Fig. 3 Boxplot of PFOS concentration (in nanogrammes per millilitre) according to parity
age range
40-49
50-53
N= 18
N= 5
ΣPFASs levels in blood. The specific exposure route is not yet unrevealed, although the manipulation or contact with PFASs containing products can represent an important uptake pathway. A specific case of contaminant exposure is laboratory working conditions, where personnel can be exposed through manipulation and preparation of samples and standards or through indirect pathways such as air. Although working conditions must ensure minimal contact with chemicals, it is inevitable that the ambient air contains traces of PFASs or other contaminants. To explore whether laboratory workers might be exposed to PFASs, the first step was to evaluate the levels of PFASs in personnel from the Department of Environmental Chemistry (n=16), including technicians and researchers and to compare it with the general population (n= 30). Considering laboratory workers (n=16), PFOS was the main compound detected at 0.13–3.35 ng mL−1, followed by PFOA that ranged from 0.15 to 1.08 ng mL−1, and both compounds were detected in all samples analysed. PFHxS was detected in 10 samples out of 16 and ranged from 0.10 to 0.57 ng mL−1. PFBS and PFNA were only detected in four samples at 0.1 to 0.43 ng mL−1 and 0.05 to 0.12 ng mL−1, respectively. In the general population (n=30), PFOS ranged from 0.11 to 2.60 ng mL −1 and PFOA from 0.07 to 1.03 ng mL−1. PFHxS was detected in 24 samples out of 30 at 0.09 to 0.87 ng mL−1, PFBS was detected in 12 samples at 0.04 to 0.31 ng mL−1, and PFNA was detected in 14 samples at 0.06 to 2.94 ng mL−1. No significant differences were observed between laboratory workers and the general population, being the mean values of ΣPFASs 1.59 ± 0.59 ng mL−1 and 1.85±1.04 ng mL−1, respectively (Fig. 1). Considering individual compounds, PFOA levels differed significantly between laboratory workers and the rest of population (p=0.0062) whereas no differences were observed for the other compounds. According to these results, laboratory personnel from the Department of Environmental Chemistry could be affected by direct exposure to PFOA, although the specific sources of contamination should be further explored.
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Therefore, while working in the laboratory of the Department of Environmental Chemistry might have an influence on the accumulation of PFOA, other professions can also contribute to the accumulation of PFASs in humans as these compounds are present in many goods and consumer products. Age PFASs, in special PFOS, are bioaccumulative and therefore an increase of their concentrations in humans with age is expected. In humans, it has been suggested that 20 years is enough to accumulate PFOS and PFOA at nanogrammes per millilitre levels in blood (Kärrman et al. 2006). The age cohort studied ranged from 19 to 53 years. When dividing by age groups (Fig. 2), no significant differences were observed on the ΣPFASs levels. Contrarily to what was expected, the highest age group, corresponding to >50 years, did not have higher ΣPFASs levels than younger people (Fig. 2). However, when considering individual compounds, PFOS (p=0.0387) and PFHxS (p=0.0299) had significant differences between age groups. Levels of PFOS in the 19–29 age group were the highest and decreased gradually up to the 40–53 age group, indicating a specific high PFASs exposure of young people due to early exposure, compared to other age groups. Similar to our study, Ericson et al. (2007) analysed PFASs in 48 human blood and found that PFHxS levels were significantly higher (p < 0.05) in the group of 25 ± 5 years (4.65 ± 3.70 ng mL−1) compared to the 55±5 age group (2.48± 1.39 ng mL−1) (Ericson et al. 2007). Gender, parity and habits The mean level for ΣPFASs in males was 1.81±0.99 ng mL−1 (n=20) slightly higher than in females that was of 1.57± 0.80 ng mL−1 (n=26) (Table 1, Fig. 1). No significant differences were found among any PFASs levels considering gender (p>0.1114). However, Fromme et al. (2007) analysed 356 human plasma samples from an adult population in Germany. In females, the levels were from 2.5 to 30.7 ng mL−1 for PFOS and from 1.5 to 16.2 ng mL−1 for PFOA and in males, the levels were from 2.1 to 55 ng mL−1 for PFOS and from 0.5 to 19.1 ng mL−1 for PFOA and significant correlation between both PFOS and PFOA concentrations and gender was observed (Fromme et al. 2007). On the other hand, parity had an influence in PFASs levels. Figure 1 shows the mean levels of ΣPFASs in women without children and in primiparae/ multiparae mothers, the latter being slightly lower. PFASs levels in blood from females without children ranged from 0.11 to 3.61 ng mL − 1 while lower levels (0.55 to 2.20 ng mL−1) were detected in mothers. According to ANOVA (Fig. 3), PFOS showed significant differences between both groups (p=0.0065). However, it should be taken into account that women without children were almost in the
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age group of 19–29 (only one was 33) and most of the mothers were in elder groups. So, the significant difference of PFOS between women without children and mothers was also affected by differences between age groups. Transfer of PFASs to the foetus during pregnancy or during breastfeeding has been identified as a way of releasing PFASs from body burdens (Brantsæter et al. 2013; Porpora et al. 2013). Other factors affecting PFASs accumulation are specific habits such as diet or smoking. Samples analysed corresponded to people who live in Barcelona. In this area, dietary habits consist in white fish, meat (little pork), olive oil, fruits and vegetables. Thus, it is expected a typical Mediterranean diet, although specific dietary habits on the accumulation of PFASs, were not studied. As for smoking habits, no differences were observed between smokers and non-smokers (Fig. 1), although smoking is not known to influence PFOS and PFOA levels (Midasch et al. 2006).
Conclusions PFASs were detected in all 46 blood samples from residents of Barcelona at low concentration levels. Laboratory workers, dentists, truck drivers, and salesmen had higher PFASs than the mean, but only PFOA level was statistically different from laboratory workers than in the general population. Contrarily, age and parity produced a significant difference on the levels of PFASs in blood, with decreasing levels with age or parity. Because PFASs were detected in all samples, exposure is generalized to the overall population and given the potential toxicity of PFASs, it is important to minimize contact or manipulation of PFASs containing products to avoid longterm accumulation and potential health effects. Acknowledgements Montserrat March, the nurse from our institute is acknowledged for organising the extraction of blood from workers from the Department of Environmental Chemistry of IDAEA-CSIC. Our friends, Anna Daví and Patricia López, are acknowledged for the extraction of blood of the “general population”. All donors are deeply thanked for their contribution and interest in the study.
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