Multiple pathways of human exposure to poly- and perfluoroalkyl substances (PFASs): From external exposure to human blood.

Exposure to PFASs may result in adverse health effects. This study aimed to characterise the exposure to PFASs from diet, house dust, indoor air, and dermal contact and the relative contribution from different external exposure pathways to human serum concentrations. Daily intakes of 18 perfluoroalkyl acids (PFAAs) and 12 PFAA precursors from diet, dust ingestion, inhalation of indoor air and dermal absorption were estimated using a comprehensive dataset comprising 61 adults from the Oslo area, Norway. Concentrations of PFAAs and PFAA precursors in house dust, indoor air, hand wipes, foods and drinks were utilised to estimate the daily intakes. Perfluorooctanesulfonate (PFOS) was the predominant PFAS in serum for this study group. On a median level, perfluorooctanoate (PFOA) contributed most to the total estimated daily intake of PFAAs, with a median intake of 280 (range: 72-1810) pg·kg bw-1·day-1, covering both direct and indirect (precursors) exposure. Out of this, only 3% (range: <1-48%) of the total PFOA intake came from indirect exposure. Dietary exposure from ingestion of food and drinks was in general the predominant exposure pathway, followed by exposure from ingestion of house dust, inhalation of indoor air, and dermal absorption, but considerable variations were observed among individuals. House dust ingestion and indoor air inhalation contributed most to the total intakes for some participants, for which most of them were among the 20% participants with the highest total estimated intakes. Some statistical significant associations between concentrations of PFASs measured in serum and estimated intakes were observed. Measured serum concentrations and modelled serum concentrations based on external exposure estimates were in the same order of magnitude for PFOS, PFHxS, PFOA, and PFNA, but only PFOA concentrations were comparable, 1.9 and 2.0 ng mL-1 for observed and modelled serum concentrations, respectively. The estimated daily intakes of PFASs in this study were lower than the health-based guidance values, e.g. the tolerable weekly intakes derived by EFSA. This study underlines the importance of performing studies considering multiple exposure pathways on an individual basis.

Hand Wipes: A Useful Tool for Assessing Human Exposure to Poly- and Perfluoroalkyl Substances (PFASs) through Hand-to-Mouth and Dermal Contacts.

The indoor environment contributes considerably to human exposure to poly- and perfluoroalkyl substances (PFASs). This study estimated the human exposure to PFASs from the indoor environment through hand-to-mouth and dermal contacts using hand wipes. An analytical method was developed to determine 25 PFASs in hand wipe samples collected as a composite sample from both hands of 60 adults. Polyfluoroalkyl phosphate esters (PAPs) were the predominant PFASs in the hand wipe samples (medians between 0.21 and 0.54 ng per sample). Positive and significant correlations were observed between PAPs, perfluorooctanesulfonate (PFOS), and perfluorooctanoate (PFOA) in hand wipes. Low frequency of daily hand washing (≤8 times day-1) was associated with 30-50% higher concentrations of PFOS, PFOA, and 8:2diPAP in hand wipes. Further, significant correlations between paired hand wipes and house dust samples were observed for PFOS, PFOA, and 6:2diPAP. Also, a significant correlation between PFOS in hand wipes and EtFOSE in indoor air was found. This finding indicates either a common source of exposure or a transformation of EtFOSE to PFOS in the environment or on the hands. The contributions of direct and indirect exposure to perfluoroalkyl acids (PFAAs) showed that PFOA contributed the highest exposure to adults via hand-to-mouth and dermal contacts, followed by PFOS. The median of estimated daily intakes via hand-to-mouth and dermal contacts (for hands only) for PFOA were 0.83 and 0.50 pg·kg bw-1·day-1, respectively. This study gives a first indication that PFAS concentrations in hand wipes can be used as a proxy for the exposure to PFASs from indoor environments, but further studies are needed to confirm this.

Dried blood spots for reliable biomonitoring of poly- and perfluoroalkyl substances (PFASs).

Dried blood spot (DBS) sampling has gained attention in several scientific areas because of the low sampling burden. The study aimed to develop a method for the determination of poly- and perfluoroalkyl substances (PFASs) in DBS using a standardized blood volume. The DBS method using a simple methanol extraction followed by online solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry quantification was validated. Only 30 µL of blood is required. Based on the measurements of DBS dispersed areas from known blood volumes (20-70 µL), the blood volume on a 3 mm diameter DBS subsample was calculated to be 3.3 µL (median, n = 708 measurements, 59 adults). Strong correlations of PFAS concentrations between finger prick DBSs and venous whole blood samples (n = 57) were found (rho 0.72-0.97, p < 0.0001). Also, Passing-Bablok regressions and Bland-Altman plots demonstrated good agreements of PFAS concentrations in finger prick DBSs and venous whole blood samples. This finding indicates that the DBS method was satisfactory, and allows straightforward analysis of PFASs in DBS without hematocrit correction. This DBS method is reliable for accurate determination of PFASs and has a high potential for use of self-collected DBS in large-scale biomonitoring studies as well as for archived DBS samples.

Investigation of the Best Approach for Assessing Human Exposure to Poly- and Perfluoroalkyl Substances through Indoor Air.

Per- and polyfluoroalkyl substances (PFASs), including fluorotelomer alcohols (FTOHs), perfluoroalkyl sulfonamidoethanols (FOSEs), and perfluoroalkyl sulfonamides (FOSAs), were assessed in 61 residential indoor air and 15 personal air samples collected in Oslo area, Norway. FTOHs were detected in all samples, and the median concentrations in residential indoor air were 2970, 10400, and 3120 pg m-3 for 6:2, 8:2, and 10:2 FTOH, respectively. This is similar to or higher than previously reported in studies from the same geographical area and worldwide. FOSEs and FOSAs were detected in 49-70% and 7-13% of the residential indoor air samples, respectively. The median FTOH concentrations observed in personal air were 1970, 7170, and 1590 pg m-3 for 6:2, 8:2, and 10:2 FTOH, respectively, which is 30 to 50% lower than the median concentrations in residential indoor air. No FOSEs or FOSAs were detected above the method detection limit (MDL) in the personal air samples. Intakes of perfluorohexanoate (PFHxA), perfluoroheptanoate (PFHpA), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), perfluoroundecanoate (PFUnDA), and perfluorooctyl sulfonate (PFOS) through inhalation and biotransformation of PFAS precursors in air were estimated. Median intakes of 1.7, 0.17, 5.7, 0.57, 1.8, 0.18, and 2.3 pg kg bw-1 day-1 were obtained in residential indoor air, while 1.0, 0.10, 3.3, 0.33, 0.88, and 0.09 pg kg bw-1 day-1 were found in personal air for PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnDA, and PFOS, respectively. The median PFOA intakes from residential indoor air (5.7 pg kg bw-1 day-1) and personal air (3.3 pg kg bw-1 day-1) were both around 5 orders of magnitude lower than the tolerable daily intake (TDI) reported by the European Food Safety Authority (EFSA).

Distribution of Novel and Well-Known Poly- and Perfluoroalkyl Substances (PFASs) in Human Serum, Plasma, and Whole Blood.

Currently, there is limited knowledge on the distribution of poly- and perfluoroalkyl substances (PFASs) in different blood matrices, particularly for novel PFASs such as polyfluoroalkyl phosphate esters (PAPs) and perfluoroalkyl phosphonates (PFPAs). To explore this, serum, plasma, and whole blood from 61 adults in Oslo, Norway were collected. The largest number of PFASs were detected in whole blood. For PAPs and PFPAs, the highest frequencies of detection and concentrations were observed in plasma. PAPs contributed to 8% of total PFASs in plasma (median, 0.81 ng mL-1). Perfluorohexylphosphonate (PFHxPA) was the dominant PFPA, regardless of blood matrix. The relative composition profiles of PFASs in blood matrices differed. For some specific PFASs such as perfluorooctanesulfonamide (PFOSA) and perfluorohexanoate (PFHxA), the highest concentrations were observed in whole blood. The PFAS concentration ratios varied between blood matrices, depending on the compounds. However, similar ratios were observed for 6:2 polyfluoroalkyl phosphate diester (6:2diPAP) as well as well-known PFASs such as perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA). Besides the determination of 25 PFASs in human blood, this study also lead to better understanding of biomonitoring data from different blood matrices, which is key knowledge for performing both exposure assessments and epidemiological studies.

Estimating human exposure to perfluoroalkyl acids via solid food and drinks: Implementation and comparison of different dietary assessment methods.

BACKGROUND: Diet is a major source of human exposure to hazardous environmental chemicals, including many perfluoroalkyl acids (PFAAs). Several assessment methods of dietary exposure to PFAAs have been used previously, but there is a lack of comparisons between methods. AIM: To assess human exposure to PFAAs through diet by different methods and compare the results. METHODS: We studied the dietary exposure to PFAAs in 61 Norwegian adults (74% women, average age: 42 years) using three methods: i) by measuring daily PFAA intakes through a 1-day duplicate diet study (separately in solid and liquid foods), ii) by estimating intake after combining food contamination with food consumption data, as assessed by 2-day weighted food diaries and iii) by a Food Frequency Questionnaire (FFQ). We used existing food contamination data mainly from samples purchased in Norway and if not available, data from food purchased in other European countries were used. Duplicate diet samples (n=122) were analysed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) to quantify 15 PFAAs (11 perfluoroalkyl carboxylates and 4 perfluoroalkyl sulfonates). Differences and correlations between measured and estimated intakes were assessed. RESULTS: The most abundant PFAAs in the duplicate diet samples were PFOA, PFOS and PFHxS and the median total intakes were 5.6ng/day, 11ng/day and 0.78ng/day, respectively. PFOS and PFOA concentrations were higher in solid than liquid samples. PFOS was the main contributor to the contamination in the solid samples (median concentration 14pg/g food), while it was PFOA in the liquid samples (median concentrations: 0.72pg/g food). High intakes of fats, oils, and eggs were statistically significantly related to high intakes of PFOS and PFOA from solid foods. High intake of milk and consumption of alcoholic beverages, as well as food in paper container were related to high PFOA intakes from liquid foods. PFOA intakes derived from food diary and FFQ were significantly higher than those derived from duplicate diet, but intakes of PFOS derived from food diary and FFQ were significantly lower than those derived from duplicate diet. We found a positive and statistically significant correlation between the PFOS intakes derived from duplicate diet with those using the food diary (rho=0.26, p-value=0.041), but not with the FFQ. Additionally, PFOA intakes derived by duplicate diet were significantly correlated with estimated intakes from liquid food derived from the food diary (rho=0.34, p=0.008) and estimated intakes from the FFQ (rho=0.25, p-value=0.055). CONCLUSIONS: We provide evidence that a food diary or a FFQ-based method can provide comparable intake estimates to PFOS and PFOA intakes derived from a duplicate diet study. These less burdensome methods are valuable and reliable tools to assess dietary exposure to PFASs in human studies.

High throughput online solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry method for polyfluoroalkyl phosphate esters, perfluoroalkyl phosphonates, and other perfluoroalkyl substances in human serum, plasma, and whole blood.

A rapid, sensitive and reliable method was developed for the determination of a broad range of poly- and perfluoroalkyl substances (PFASs) in various blood matrices (serum, plasma, and whole blood), and uses only 50 µL of sample material. The method consists of a rapid protein precipitation by methanol followed by high throughput online solid phase extraction (SPE), ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS), and negative electrospray ionization detection. The method was developed for simultaneous determination of twenty-five PFASs, including polyfluoroalkyl phosphate esters (PAPs; 6:2, 8:2, 6:2/6:2, and 8:2/8:2), perfluoroalkyl phosphonates (PFPAs; C6, C8, and C10), perfluoroalkyl sulfonates (PFSAs; C4, C6, C7, C8, and C10), perfluoroalkyl carboxylates (PFCAs; C5C14), and perfluoroalkyl sulfonamides (FOSAs; C8, N-methyl, and N-ethyl). High linearity of matrix-matched calibration standards (correlation coefficients, R = 0.99-0.999) were obtained in the range of 0.006-45 ng mL-1 blood. Excellent sensitivity was achieved with method detection limits (MDLs) between 0.0018 and 0.09 ng mL-1, depending on the compound and matrix. The method was validated for serum, plasma, and whole blood (n = 5 + 5) at six levels in the range 0.0180-30 ng mL-1. The accuracy (n = 5) was on average 102± 12%. The intermediate precision (n = 10) ranged from 2 to 40% with an average between-batch of analyses difference of 10± 10%. Two human serum samples from a former interlaboratory comparison were analyzed and the differences between the applied method and the consensus values were below ≤22% (n = 5). The method was also successfully applied to samples of human plasma and whole blood with coefficients of variation in the range 0.8-15.2% (n = 5).

Determination of perfluorooctane sulfonate and perfluorooctanoic acid in food packaging using liquid chromatography coupled with tandem mass spectrometry.

This research aimed to monitor the amounts of PFOS and PFOA in food packaging and study the migration of PFOS and PFOA from food packaging, using a saliva simulant and pressurized liquid extraction (PLE) technique. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was employed to determine residues of PFOS and PFOA by using a gradient reversed-phase method with ammonium acetate/acetonitrile buffer. A good linearity was established for PFOS and PFOA in a range of 0.05-10 µgL(-1), with R2 ≥ 0.9998. Of the samples extracted by methanol, the highest concentration of PFOS was found in fast-food container samples, at a level of 92.48 ng dm(-2). For PFOA, the highest concentration in samples extracted by methanol was found in ice cream cup samples, at a level of 16.91 ng dm(-2). The amounts of PFOS and PFOA that migrated from food packaging samples through contact with saliva simulant were 4.80 and 4.55 ng dm(-2), respectively. Saliva simulant could leach PFOS and PFOA from the group of the thickest paper samples (≤1 dm2 g(-1)) at levels of 7.01 and 6.41 ng dm(-2), respectively, indicating that paper with greater thickness and less area might release larger quantities of coated/added PFOS or PFOA.