Occurrence, Fate and Effects of Fluorinated Surfactants in the Canadian Environment

Principle Investigator:
Scott Mabury
Department of Chemistry
University of Toronto
80 George St.
Toronto, ON M5S 3H6

smabury@alchemy.chem.utoronto.ca

Contributing Partner(s):
Derek Muir, Environment Canada
Brian Scott, Environment Canada
Keith Solomon, University of Guelph

Project Length:
3 Years

Funding:
1999-2000: $180,000
2000-2001: $208,000
2001-2002: $208,000

Why Project Was Undertaken: Fluorinated surfactants (FSs) are used in industry to lubricate machinery, in molds and as fire retardants and many other uses. Consequently, FSs are present in a wide variety of industrial and consumer products. FSs have been found in air and water samples, in the blood of humans across the world and in the tissues of Arctic mammals. These data indicate that FSs are wide spread in the environment. Little is known about the properties and behaviour of these chemicals in the environment or about their potential for causing harmful effects.

How Project Was Conducted: The overall objective of TSRI Project #200 was to study the relationship between the physical-chemical properties and structures of FSs and how they travel, distribute and accumulate in air, water, sediment and aquatic organisms. This project involved a series of laboratory experiments and field studies of FSs. New methods were developed to measure FSs in air, water and living organisms. Measurements were made of their tendency to accumulate in tissues of fish, bind to sediments and volatilize to air. Toxicity studies were conducted in different aquatic organisms and the fate and effects of an FS spill was monitored in a creek.

What Was Found and Conclusions: TSRI Project #200 increases the understanding of FSs in the environment and provides new methods to measure low levels of FSs in tissues, water, sediment, air. FS molecules have a chemical "head" and a chemical "tail" of a carbon and fluorine chain. Studies of FSs with different "head" and "tail" features revealed that the longer the "tail" the greater the accumulation in fish. FSs did not break down under harsh conditions in the laboratory which indicates that they are likely to persist in the environment. Toxic effects of FSs in aquatic invertebrates, fish and aquatic plants varied depending on the "head" type and the length of the "tail" of the FS. Plants were sensitive more to the short and long chain FSs and in general were more sensitive than aquatic invertebrates, except for one particularly sensitive invertebrate species. The longer "tail" FSs tended to be more persistent in the aquatic environment. FSs are found in very low levels (1 in one trillion) in lakes, rivers, rainwater and air in Canada. A previously unobserved long "tail" FSs was found in fish from a creek with an FS spill. Further toxicity testing in aquatic organisms is ongoing.

Executive Summary

The approach that our team has taken is to look at a series of perfluoroalkyl carboxylate and sulfonate fluorinated surfactants (FSs) in order to understand the structure activity with respect to chemical properties, fate, persistence, and toxicity. These data will be useful in prioritizing regulatory and research efforts towards FSs as a class of compounds. Results generated in this project have significantly increased our understanding of FSs in the environment and a significant number of fundamental discoveries have been made.

Analytical methodologies were developed, optimized, and published for the determination of FSs and/or their precursors in air, water, and biota. LC/MS/MS has been utilized to monitor Etobicoke Creek water following a FSs spill at Pearson airport and in more routine surface water monitoring. For of perfluoroalkyl carboxylates in water, a GC-based method was also used which involved derivitization to the a more volatile amide; having dual-techniques provided the opportunity for method comparisons of these compounds in surface waters in Ontario. LC/MS/MS has also proven particularly powerful for the determination of FSs in biotic samples. For volatile FS precursors we developed methods utilizing the resolving and detection power of GC/MS. A ¹⁹F NMR method was developed to complement the MS technique for both surface water samples and lab experiments. A robust IC method has also been utilized to support lab physical property experiments.

A suite of physical property determination experiments were instigated to specifically address the dearth of information in the open literature regarding these chemicals. Of particular importance were the bioconcentration (BCF) potential in fish, sorption behaviour towards sediment, and the volatility of the FSs themselves and more importantly that of the alcohol precursors that we hypothesized were the route by which PFOS itself was globally distributed. Bioconcentration and bioaccumulation studies, with rainbow trout, showed that a perfluorinated tail with greater than 7 carbons resulted in measurable accumulation in the fish, that sulfonates had higher accumulation potential than carboxylates, each BCF₂ group increased the -CF by ~10, and the tissue distribution showed FSs were primarily in non-lipid tissues such as blood, liver, pancreas, etc.

Overall the BCF ranged from 25 for PFOA to 20,000 for PFTA (C¹⁴F¹⁷O²H) in blood. Sorption experiments showed similar results with linear isotherms increasing with both perfluorochain length and organic matter content in soils. Vapour pressures for neutral "alcohol" precursors gave extremely high values with respect to the relatively large molecular mass. These measurements were difficult to make and are now being repeated to obtain more accurate values ~ the data obtained did direct us in our other field monitoring studies and in developing the GC-based analysis techniques. Henry's Law constant and vapour pressure were determined for a series of perfluoroalkyl carboxylates in their protonated form. ¹⁹F NMR proved particularly useful at interrogating the influence of chain length on the rigidity of the molecule.

In progress still are measurements of vapour pressure, Henry's Law, and octanol-air partition coefficients for a suite of volatile FSs precursors as well as new compounds discovered in the course of this project. Additionally, we have instigated measurements of the cross-sectional gas-phase infrared absorption spectra of those FS precursors we have measured in our monitoring study with the objective of calculating their global warming potential. Attempts at degrading any of the FSs via oxidative or reductive means ~ even under extreme conditions ~ proved futile. We have coined the phrase Aredefining persistence to describe the FSs class to differentiate their stability in relation to notorious and yet highly labile, in comparison, chlorinated pesticides and industrial compounds.

Extensive lab and field (mesocosm) toxicity testing of a the perfluoroalkyl carboxylates and sulfonates indicated toxicity varied with chain length and polar functionality (e.g. carboxylate or sulfonate) and that although most organisms showed only moderate effects from aqueous exposures, some species were highly sensitive to PFOS. Plants generally were the most sensitive to the short and long chain (C8>C10>C9>C3>C4 .C5 = C7) while some zooplankton showed only sensitivity to the higher homologues. PFOS was more toxic than the other compounds tested with plants generally more sensitive than invertebrates although for all compounds tested across a wide range of organisms, toxicity was only observed in the ppm range. An exception and major discovery was the observation that an aquatic midge (C. tentans) was extremely sensitive to PFOS. One experiment resulted in an LC₅₀ of 42.2 ppb while comparable values for Daphnia were ~3,500 times higher. Significant effort is now being expended on clarifying this observation and confirming mechanism of action.

Creek water samples obtained downstream of a FS spill ranged in concentration from ppm to low ppb for a suite of perfluoroalkyl carboxylates and sulfonates. Interestingly, PFOA was observed at low ppt concentrations upstream of the spill. L C/ MS/ MS has also proved powerful in measuring FSs in fish from the creek and in the discovery of a suite of previously unobserved long-chain perfluoroalkyl carboxylates (C10 to C14). This observation is important because the longer chain perfluoroalkyl carboxylates are more bioaccumulative, and in some cases may be more toxic, than the shorter chain versions. This discovery was made possible, in part, because the objectives of the research were to look at the entire class of anionic perfluorinated surfactants rather than individual chemicals (e.g. PFOS). We have recently observed these longer chain perfluoroalkyl carboxylates in Arctic mammals suggesting wide- dissemination of these materials in the environment. A further discovery was the measurement of a field bioaccumulation factor (BAF) for PFOS higher (6,000 to 125,000) than the value obtained in lab experiments (~5,000). We hypothesize that other chemicals found in the creek were being metabolized to PFOS resulting in an artificially high BAF value, although other mechanisms could be important as well. Extensive sampling of surface and rain waters across Ontario and Canada showed that are widespread in surface waters in the low ppt/high ppq range. Fewer samples have been analyzed for the sulfonates (e.g. PFOS) but typically it is found at the ppq range. We hypothesized that volatile >alcohol= precursors were responsible for the world-wide dissemination of PFOS and related FSs in the environment. Air sampling for these in Ontario (urban and rural), and in a more extensive study across North America, showed these compounds were present at concentrations ranging from 10 to 100s of pg/m3. Further, we also discovered a new class of fluoro-alcohol air pollutant in the "fluorotelomer alchols" or FTOHs at similar concentrations.

This project has been highly successful in revealing a number of the fundamental properties of FSs, in developing methods and technologies for their study, for making major discoveries that will be highly influential to both scientists and regulators, and in communicating the results of this research via publishing papers and in giving presentations to scientific meetings as well as attracting media interest. While a number of experiments continue, all of the major objectives of the proposal were met and in most cases exceeded. Quite a few new areas of research inquiry, with leverage funding from other government and private sources and new scientific collaborators, have been initiated. Many of our students have already successfully defended their dissertations/thesis and have found excellent jobs in the private and public sectors. Evidence suggests that the papers resulting from this project are already having impact in the scientific and regulatory realm, which will only be intensified in the fullness of time when all the papers/presentations arising from this project are delivered. FSs are a fascinating class of compounds that challenge some of our notions about chemical fate and disposition, and ultimately represent a whole new class of environmental pollutant.

Publications

Publications in scientific journals

Accepted/Published articles

Ellis, D.A., Cahill, T.M., Mabury, S.A., Cousins, I., Mackay, D. 2002. "Partitioning of Organofluorine Compounds in the Environment." Chapter in Handbook of Environmental Chemistry, A. Nielson (Ed) Springer-Verlag, Heidelberg. In press.

Ellis, D.A., Moody, C.A., Mabury, S.A. 2002. "Trifluoroacetic Acid and Longer Chain PerfluoroAcids B Sources and Analysis". Chapter in Handbook of Environmental Chemistry, A. Nielson (Ed) Springer-Verlag, Heidelberg. In press.

Martin, J., Mabury, S.A., Solomon, K.S., Muir, D.C.G. 2002. Bioconcentration and Tissue Distribution of Perfluorinated Acids in Rainbow Trout (Oncorhynchus mykiss). Environ. Toxic. Chem. In press.

Martin, J., Mabury, S.A., Solomon, K.S., Muir, D.C.G. 2002. Dietary Accumulation of Perfluorinated Acids in Rainbow Trout (Oncorhynchus mykiss). Environ. Toxic. Chem. In press.

Martin, J.W., Muir, D.C.G., Kwan, W.C., Moody, C.A., Solomon, K.R., Mabury, S.A. 2002. Collection of Airborne Fluorinated Organics and Analysis by Gas Chromatography-Chemical Ionization-Mass Spectrometry. Anal. Chem. 74:584-590.

Moody, C.A., Kwan, W.C., Martin, J.W., Muir, D.C.G., Mabury, S.A. 2001. Determination of Perfluorinated Surfactants in Surface Water Samples by Two Independent Analytical Techniques B Liquid Chromatography/Tandem Mass Spectrometry and 19F NMR. Anal. Chem. 73: 2200-2206.

Moody, C.A., Martin, J.W., Kwan, W.C., Muir, D.C.G., Mabury, S.A. 2002. Monitoring Perfluorinated Surfactants in Biota and Surface Water Samples Following an Accidental Fire-Fighting Foam Release into Etobicoke Creek. Environ. Sci. Tech. 36:545-551.

Sanderson, H., Boudreau, T.M., Mabury, S.A., Cheong, W.J., Solomon, K.R. 2002. Ecological Impact and Environmental Fate of Perfluoroctane Sulfone (PFOS) on the Zooplankton Community in Indoor Microcosms. Environ. Toxic. Chem. In press.

Submitted articles

Boudreau, T. M., Sibley, P.K., Muir, D.C.G., Mabury, S.A., Solomon, K.R. 2002. Laboratory evaluation of the toxicity of perfluorooctane sulfonate (PFOS) to Selenastrum capricornutum, Chlorella vulgaris, Lemna gibba, Daphnia magna, and D. pulicaria.

Kwan, W.C., Sullivan, R.C., Small, J.M., Mabury, S.A. 2001. Comparison of Anion Exchange and Reverse Phase Ion Chromatography for the Determination of Perfluorinated Carboxylate and Sulfonate Surfactants. Submitted.

Sanderson, H., Boudreau, T.M., Mabury, S.A., Solomon, K.R. 2002. Ecological Impact Perfluorooctanoic Acid on the Zooplankton Community in Indoor Microcosms. Submitted.

Theses

Chau, K. 2002. M.Sc. thesis. "Analytical Determination of Degradation Products of 1H,1H, 2H, 2H perfluorooctane Sulfonate". University of Lund, Sweden.

Martin, J. 2002. Ph.D. Thesis. "XXX". University of Guelph.

Sanderson, H. 2002. Ph.D. thesis. "Design, Analysis and Interpretation of Higher Tier Risk assessment of chemicals in aquatic microcosms". University of Roskilde, Denmark.

Kwan, W.C. 2001. M.Sc. thesis. "Physical Property Determination of Perfluorinated Surfactants." University of Toronto