Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Human exposure to perfluoroalkyl acids
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) are persistent organic contaminants which have been globally measured in human serum samples at low μg L-1 concentrations. One hypothesis, the so-called "indirect hypothesis", postulates that exposure to precursor compounds is responsible for the presence of PFCAs and PFSAs in human serum. The main purpose of this thesis was to test an alternative hypothesis that direct intake of PFCAs and PFSAs via the diet is the dominant ongoing pathway of exposure. Exposure modeling results in paper I and II demonstrate that dietary intake is the major exposure pathway of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), while known precursors account for only a few percent of the total exposure. To address the uncertainties related to dietary intake pathways, highly sensitive analytical methods for a range of PFCAs and PFSAs are developed, validated and applied in paper III and IV. By the development of a novel analytical technique in paper III, detection limits in the pg g-1 range are achieved for a wide range of analytes in different food categories. Analysis of a large set of food basket samples from the Swedish market in paper IV shows that the concentrations in many dietary samples are lower than those used to estimate exposure to PFOA and PFOS in paper I and II. However, an updated dietary intake estimate in paper IV supports the conclusion of paper I and II that dietary intake is the major ongoing human exposure pathway for the general population. Pharmacokinetic modeling undertaken in paper II was reevaluated in this thesis and back-calculated daily intakes from serum concentrations of PFOA and PFOS are shown to be in agreement with the estimated dietary intakes from paper IV. However, due to uncertainties and simplifying assumptions in the pharmacokinetic model, it is possible that there are additional pathways of human exposure contributing to human serum levels.

Place, publisher, year, edition, pages
Stockholm: Department of Applied Environmental Science (ITM), Stockholm University , 2011. , 46 p.
National Category
Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
URN: urn:nbn:se:su:diva-63685ISBN: 978-91-7447-391-9 (print)OAI: oai:DiVA.org:su-63685DiVA: diva2:451723
Public defence
2011-12-02, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 4: Manuscript.Available from: 2011-11-10 Created: 2011-10-26 Last updated: 2011-10-31Bibliographically approved
List of papers
1. Dietary intake estimates of perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids for the general Swedish population in 1999, 2005 and 2010
Open this publication in new window or tab >>Dietary intake estimates of perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids for the general Swedish population in 1999, 2005 and 2010
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Dietary intake has been estimated to be the major ongoing pathway of human exposure to perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs). However, difficulties associated with the analysis of food samples have hampered the reliable quantification of dietary exposure. Here the dietary exposure of the average Swedish population to PFCAs and PFSAs is estimated through analysis of a range of homologues in representative food basket samples from 1999, 2005 and 2010. Exposure to perfluorooctane sulfonate (796−1424 pg kg

-1day-1), perfluoroundecanoic acid (88−212 pg kg-1day-1), perfluorodecanoic acid (52−102 pg kg-1day-1) and perfluorononanoic acid (62−83 pg kg-1day-1) was dominated by the consumption of fish and meat. In contrast, exposure to perfluorooctanoic acid (322−513 pg kg-1day-1) originated from low levels (8−62 pg g-1) found in several ―high consumption‖ food categories including cereals, dairy products, vegetables and fruit. The average body weight normalized dietary intakes (pg kg-1day-1) were fairly constant between 1999 and 2010 for all PFCAs and PFSAs demonstrating that dietary intake has been a continuous exposure pathway for these compounds during this period when many manufacturing changes occurred. Although statistically significant temporal trends in the average dietary intake estimates could not be determined, there is preliminary evidence of a downward time trend in the concentrations of PFOS in eggs and meat products and an upward trend of PFDA, PFUnDA, perfluorododecanoic acid and perfluorotridecanoic acid in fish products, which both warrant further investigation. In line with recent studies, dietary intake was found to be the major ongoing human exposure pathway for both PFOA and PFOS (~70% of the total exposure) for the Swedish population compared to exposure via ingestion of household dust and drinking water. The calculated higher total dietary exposure to PFOA compared to PFNA is consistent with the pattern observed in human serum, although there are several other exposure pathways which could explain this homologue pattern in serum.

National Category
Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-63657 (URN)
Available from: 2011-10-26 Created: 2011-10-26 Last updated: 2011-10-27Bibliographically approved
2. Tracking the pathways of human exposure to perfluorocarboxylates
Open this publication in new window or tab >>Tracking the pathways of human exposure to perfluorocarboxylates
2009 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 43, no 15, 5565-75 p.Article in journal (Refereed) Published
Abstract [en]

Recent analyses of perfluorooctanoate (PFOA) in human blood sera show that the background-exposed population in industrialized countries worldwide exhibits a narrow concentration range; arithmetic means of published studies range between 2 and 8 microg/L PFOA, with the exception of a few outlier studies. The globally comparable human serum concentrations of PFOA and characteristic dominance of PFOA with respect to other perfluorocarboxylate (PFCA) homologues indicate that exposure pathways of humans differ from those of wildlife, where perfluorononanoate (PFNA) is often the dominant homologue. The observed correlations between perfluorooctane sulfonate (PFOS) and PFOA in human serum together with a simultaneous downward time trend of these compounds in human blood sera and blood spots from the year 2000 onward indicate a connection between historical perfluorooctanesulfonyl (POSF) production (phased out by the major manufacturer in 2000-2002) and exposure to both PFOS and PFOA. A comparison of estimated daily intakes to humans based on samples from exposure media (collected post 2000) indicates that food intake is the major contemporary exposure pathway for the background population, whereas drinking water exposure is dominant for populations near sources of contaminated drinking water. A one-compartment pharmacokinetic model used to back-calculate daily intakes from serum levels is shown to provide agreement within a factor of 1.5-5.5 of the daily intakes derived from exposure media, which provides further supporting evidence that dietary exposure is a major ongoing exposure pathway of PFOA to the background population.

National Category
Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-34630 (URN)10.1021/es900228k (DOI)000268480600007 ()19731646 (PubMedID)
Available from: 2010-01-11 Created: 2010-01-11 Last updated: 2017-12-12Bibliographically approved
3. Estimating the contribution of precursor compounds in consumer exposure to PFOS and PFOA
Open this publication in new window or tab >>Estimating the contribution of precursor compounds in consumer exposure to PFOS and PFOA
Show others...
2008 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 73, no 10, 1617-1624 p.Article in journal (Refereed) Published
Abstract [en]

The exposure of humans to perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) was quantified with emphasis on assessing the relative importance of metabolic transformation of precursor compounds. A Scenario-Based Risk Assessment (SceBRA) approach was used to model the exposure to these compounds from a variety of different pathways, the uptake into the human body and resulting daily doses. To capture the physiological and behavioral differences of age and gender, the exposure and resulting doses for seven consumer groups were calculated. The estimated chronic doses of a general population of an industrialized country range from 3.9 to 520 ng/(kg day) and 0.3 to 140 ng/(kg day) for PFOS and PFOA, respectively. The relative importance of precursor-based doses of PFOS and PFOA was estimated to be 2–5% and 2–8% in an intermediate scenario and 60–80% and 28–55% in a high-exposure scenario. This indicates that sub groups of the population may receive a substantial part of the PFOS and PFOA doses from precursor compounds, even though they are of low importance for the general population. Similar to a preceding study, uptake of perfluorinated acids from contaminated food and drinking water was identified as the most important pathway of exposure for the general population. The biotransformation yields of telomer-based precursors and to a lesser extent perfluorooctanesulfonylfluoride-based precursors were identified as influential parameters in the uncertainty analysis. Fast food consumption and fraction of food packaging paper treated with PFCs were influential parameters for determining the doses of PFOA.

National Category
Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-63655 (URN)1016/j.chemosphere.2008.08.011 (DOI)
Available from: 2011-10-26 Created: 2011-10-26 Last updated: 2017-12-08Bibliographically approved
4. A matrix effect-free method for reliable quantification of perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids at low parts per trillion levels in dietary samples
Open this publication in new window or tab >>A matrix effect-free method for reliable quantification of perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids at low parts per trillion levels in dietary samples
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In recent exposure modeling studies diet has been identified as the dominant pathway of human exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). However, the paucity of highly sensitive and accurate analytical data to support these studies means that their conclusions are open to question. Here a novel matrix effect-free method is described for ultra-trace analysis of perfluoroalkyl carboxylic acids (PFCAs, all homologues from perfluorohexanoic acid to perfluorododecanoic acid) and perfluoroalkane sulfonic acids (PFSAs, perfluorohexane and perfluorooctane sulfonic acid) in dietary samples of varied composition. The method employs ion pair extraction of the analytes into methyl

tert-butyl ether and subsequent solid phase extraction clean-up on Florisil and graphitized carbon. Instrumental analysis was undertaken using ultra performance liquid chromatography coupled to tandem mass spectrometry. Special care was taken to avoid procedural blank contamination and potential contamination sources were elucidated. The performance of the method was evaluated for five different food test matrices including a duplicate diet sample. Method detection limits in the low to sub pg g-1 range were obtained for all target analytes, which are 5-100 times more sensitive than previously reported for duplicate diet samples. The method provided recoveries consistently between 50 and 80% for all analytes in the food matrices tested and effects of co-extracted matrix constituents on ionization were found to be negligible. Acceptable precision, defined as percentage relative standard deviation <30%, was achieved for all analytes. Accurate quantification at ultra-trace levels was demonstrated by a method intercomparison study with an independent recently developed method. For the first time the presence of long-chain PFCAs in duplicate diet samples is reported. The method presented here can thus support an improved assessment of dietary exposure to PFCAs and PFSAs. Re-analysis of duplicate diet samples, which had been previously analyzed using another older analytical methodology, indicated that human exposure to PFOA and PFOS from dietary sources may previously have been overestimated

Keyword
food, diet, human exposure, perfluoroalkyl acids, PFOA, PFOS
National Category
Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-63653 (URN)
Available from: 2011-10-26 Created: 2011-10-26 Last updated: 2011-10-27Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Vestergren, Robin
By organisation
Department of Applied Environmental Science (ITM)
Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 645 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf