R5 AM Perflourochemical Biodegradation, Fate, and Transport
Thursday, 17 November 2005: 8:00 AM - 11:40 AM in 321-323

(WAS-1118-340637) Design of Biodegradation Experiments for Fluorotelomer-Based Polymers.

Washington, John¹, Ellington, J.¹, Jenkins, Thomas¹, Evans, John¹, Henderson, W¹, ¹ USEPA, National Exposure Research Laboratory, Ecosystems Research Division, 960 College Station Rd., Athens, Georgia, USA

ABSTRACT- Fluorotelomer-based polymers (FBPs) are used in a wide variety of consumer products and are widely distributed throughout society. Accordingly, there is great interest in whether and how fast these materials might degrade in various environmental settings. Known and expected qualities of FBPs and fluorinated monomers, as well as extraction and analytical considerations, contribute challenges in logical design of FBP-biodegradation studies to avoid artifacts. Microbial enzyme induction for degradation of FBPs, should it occur, could be long relative to typical periods for biodegradation experiments; consequently, it might be advisable to collect and test acclimated as well as pristine media. A useful quality of FBPs is the chemical stability of the polymers and, therefore, half-lives are anticipated to be long relative to typical laboratory experiments. Failure to account for this stability in experimental design can affect results by: i) yielding unsatisfactory resolution of reaction rate to quantitate degradation constants; and ii) ingrowth of potential degradation products could be insufficient to determine whether the products are from leaching of residual monomers in the FBP or microbially mediated breakdown of the FBP structure. Consequently, sufficient microcosms, resources and time should be allotted to allow extended incubations. The compatibility of potential perfluorinated degradation products with glass, Teflon and other common experimental materials is uncertain with respect to irreversible sorption, diffusivity and extraneous sources of perfluorinated compounds; consequently, experimental materials must be tested for compatibility with potential degradation products. Maintenance of the air-tight integrity of reaction vessels is critical so that volatile potential degradation products will not diffuse from the containers over long experiments; this is especially relevant considering possible constraints on acceptable materials for sealing containers. Consequently, integrity of microcosm containers must be confirmed experimentally. We report: 1) how these and similar factors have affected our experimental design; and 2) on our early experimental efforts.

Key words: fluorotelomer-based polymers, biodegradation, lag phase, half life