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. Author manuscript; available in PMC: 2022 Jan 12.
Published in final edited form as: Environ Sci Technol Lett. 2021 Jan 12;8(1):59–65. doi: 10.1021/acs.estlett.0c00798

Figure 2.

Figure 2.

Inferred concentrations of oxidizable precursors and their perfluorinated chain length in AFFF using Bayesian inference and results of the TOP assay. Panels show probability density functions estimated by the nonparametric kernel density of the concentrations of oxidizable precursors in (a) a contemporary FT AFFF (Table S1 FT 1) and (b) the legacy ECF AFFF inferred using Markov chain Monte Carlo (MCMC) analysis (see Figure S1 for other contemporary FT AFFF). A high kernel density indicates greater probability of the estimate. Precursors are grouped by perfluorinated chain length and manufacturing source. ECF precursors range from 4 to 8 perfluorinated carbons (C4–C8) while FT precursors have n perfluorinated carbons followed by two aliphatic hydrocarbons (n:2, n = 4, 6, 8).