Phosphorus-Containing Fluorinated Organics: Polyfluoroalkyl Phosphoric Acid Diesters (diPAPs), Perfluorophosphonates (PFPAs), and Perfluorophosphinates (PFPIAs) in Residential Indoor Dust
De Silva, AO; Allard, CN; Spencer, C; Webster, GM; Shoeib, M
Indoor dust is thought to be a source of human exposure to perfluorocarboxylates (PFCAs) and perfluorosulfonates (PFSAs), but exposures to emerging organofluorine compounds, including precursors to PFCAs and PFSAs via indoor dust, remain unknown. We report an analytical method for measuring several groups of emerging phosphorus-containing fluorinated compounds, including polyfluoroalkyl phosphoric acid diesters (diPAP), perfluorophosphonates (PFPA), and perfluorophosphinates (PFPIA), as well as perfluoroethylcyclohexane sulfonate (PFECHS) in indoor dust. This method was used to analyze diPAP, PFPA, and PFPIA levels in 102 residential dust samples collected in 2007-2008 from Vancouver, Canada. The results indicated a predominant and ubiquitous presence of diPAPs (frequency of detection 100%, mean and median ΣdiPAPs 7637 and 2215 ng/g). Previously measured median concentrations of perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and fluorotelomer alcohols (FTOHs) in the same samples were 14-74 times lower than ΣdiPAP levels, i.e. 71 ng/g PFOS, 30 ng/g PFOA, and 152 ng/g ΣFTOHs. PFPAs and PFPIAs were detected in 62% and 85% of samples, respectively, at concentrations nearly 3 orders of magnitude lower than diPAPs (median 2.3 ng/g ΣPFPAs and 2.3 ng/g ΣPFPIAs). PFECHS was detected in only 8% of dust samples. To the best of our knowledge, this is the first report of these compounds in indoor dust. In this study, diPAP concentrations represented 98% ± 7% of the total measured analytes in the dust samples. Detection of diPAPs at such high concentrations in indoor dust may represent an important and as-yet unrecognized indirect source of PFCA exposure in humans, given the identified biotransformation pathways. Identifying the sources of diPAPs to the indoor environment is a priority for future research to improve air quality in households.
