Biodegradation of Polyfluoroalkyl Chemicals in the Environment

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Perfluoroalkyl and polyfluoroalkyl compounds (PFCs) are widely used in surface treatments for industrial and consumer products and as specialty chemicals. Currently, as many as hundreds of different applications have been developed. Though several categories of PFCs are under strict scrutiny for adverse environmental and ecological impact, the high versatility warrants their continuous use into the foreseeable future. Despite overall high stability, some polyfluoroalkyl compounds are susceptible to environmental biodegradation due to the integral aliphatic functionalities. For example, we have discovered that fluorotelomer alcohols can undergo substantial aerobic biodegradation and defluorination, contrary to conventional wisdom. Novel biodegradation mechanisms were discovered to be involved in generating new degradation products previously unknown. These findings have inspired us to re-think the environmental reactivity of highly fluorinated compounds as well as the metabolic capacities of microorganisms in the environment. In this context, we propose to examine three organosulfur polyfluoroalkyl compounds (two perfluoroalkyl sulfonamidoethanols and one fluorotelomer sulfonate) that are prominent environmental contaminants. The major approach is to apply advanced analytical techniques to elucidate aerobic biodegradation pathways and mechanisms of compounds of interest through a series of laboratory experiments. The proposed research will address the fundamental question of by what mechanisms microorganisms can cleave strong carbon-fluorine bonds. By examining the influence of chemical structure on biodegradability and defluorination potential, the research will be providing insights for designing better polyfluoroalkyl chemicals that do not lead to harmful compounds in the environment. The proposed research also has significant applicability to current international concerns by addressing how these compounds are degraded in natural and engineered treatment systems to release potentially toxic pollutants. With better understanding of such fundamental knowledge on environmental sources and fate, future environmental risk assessment and chemical regulations may be more effective in minimizing negative impact of PFCs.