Document Detail

Isomer profiling of perfluorinated substances as a tool for source tracking: a review of early findings and future applications.
MedLine Citation:
PMID:  20811863     Owner:  NLM     Status:  MEDLINE    
The two major manufacturing techniques for perfluorochemicals can be distinguished based on the isomeric profile of their products. ECF (major use from 1950s to 2002) results in a product containing both linear and branched isomers, while telomerization (major use from 2002 to present) typically yields an isomerically pure, linear product. Among the most important question today, which has implication for future regulation of these chemicals, is to what extent human and environmental exposure is from historical products (i.e., ECF) versus currently manufactured fluorochemicals (i.e., telomer). Perfluoroalkyl-chain branching can also affect the physical and chemical properties of these chemicals, which may influence their environmental transport and degradation, partitioning, bioaccumulation, pharmacokinetics, and toxicity. Unless perfluorinated substances are considered as individual isomers, much of this information will be overlooked or missed altogether, which could potentially lead to inaccuracies in human and environmental risk assessments. In this review, we have highlighted novel findings, current knowledge gaps, and areas for improvement based on early experiments on the disposition of PFA and PFA-precursor isomers in the environment. We have also emphasized the wealth of information that can potentially be gleaned from future work in this area, which renders routine adoption of isomer-specific methodologies an attractive and logical next step in the progression of fluorochemicals analysis. However, despite vast improvements in recent years, a fast and comprehensive method capable of separating all major PFA and PFA-precursor isomers, while removing interferences is still required before these methods becomes routine in most labs. Purified and characterized standards of PFOA and PFOS that have isomer profiles consistent with those of historically produced (i.e., 3M) PFOS and PFOA are also required. The limited data available on PFA isomer profiles that exist in the environment and the biological properties of each isomer suggest that examination of isomer profiles may yield clues on the source of PFA contamination to human and the environment. For example, contributions from historical versus current PFOA emissions can be quantified by examining the isomer profile in abiotic samples . Similarly, residual PFOS/PFOA in pre-2002 consumer products may be distinguished from directly emitted PFOS/PFOA by the existence of slight difference in isomer profile. PFOS signatures may also have the potential to distinguish between indirect exposure (via precursors) versus direct exposure (via the sulfonate), based on findings of isomer-specific and/or enantiospecific biotransformation in vitro. Isomer-specific monitoring extended to longer-chain PFAs may also be informative in determining current and historical exposure sources. Finally, given the recent increase of production of PFOSF-based chemicals, following their 2002 phase out, the ability of using isomer profiles to distinguish between historical and currently produced PFOS may also be possible.
Jonathan P Benskin; Amila O De Silva; Jonathan W Martin
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Reviews of environmental contamination and toxicology     Volume:  208     ISSN:  0179-5953     ISO Abbreviation:  Rev Environ Contam Toxicol     Publication Date:  2010  
Date Detail:
Created Date:  2010-09-02     Completed Date:  2010-12-14     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8703602     Medline TA:  Rev Environ Contam Toxicol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  111-60     Citation Subset:  IM    
Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, T6G 2G3, Canada.
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MeSH Terms
Environmental Monitoring / methods
Environmental Pollutants / chemistry*
Hydrocarbons, Fluorinated / chemistry*
Reg. No./Substance:
0/Environmental Pollutants; 0/Hydrocarbons, Fluorinated

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