Evaluating Neutral PFAS for Potential Dermal Absorption from the Gas Phase

Abstract

Exposures to per- and polyfluoroalkyl substances (PFAS) are of increasing concern. Assessments typically focus only on ingestion and inhalation exposure due to a lack of generally accepted approaches for estimating dermal absorption. Prior work indicates limited dermal absorption of ionic PFAS, but absorption of neutral PFAS has not been examined from the liquid vehicle or from vapor. Partitioning of semivolatile organic compounds from the gas phase to the skin surface (i.e., stratum corneum) is well known, but the potential for partitioning of neutral PFAS from the gas phase to the stratum corneum has yet to be estimated. The SPARC-estimated physicochemical properties were used to calculate transdermal permeability coefficients (k p_g) and dermal-to-inhalation (D/I) exposure ratios for two groups of neutral PFAS, including those on a U.S. Environmental Protection Agency PFAS list. 11 neutral PFAS gave calculated D/I ratios >5, indicating that direct transdermal absorption may be an important exposure pathway compared to inhalation. Data on consumer products or indoor air is needed for the 11 neutral PFAS, followed by possible biomonitoring to experimentally verify dermal absorption from air. Additional PFAS should be estimated by the protocol used here as they are identified in commercial products.

Intermolecular Interactions, Solute Descriptors, and Partition Properties of Neutral Per- and Polyfluoroalkyl Substances (PFAS)

“…Figure S10 shows a plot for 134 neutral PFAS using the log K aw and log K ow values predicted by COSMO therm . These neutral PFAS are from the lists of Kissel et al and our previous study . The data points are even more widely distributed, although the plot again shows that air is the most important phase and that the air/organic phase distribution can be an important fate determinant, except for short-chain polar PFAS, which can also be in water.…”

Characterization and dermal bioaccessibility of residual- and listed PFAS ingredients in cosmetic products

“…While listed PFAS ingredients appear relatively non-bioaccessible compared to residual PFCAs using artificial sweat, these substances may still pose a risk, either from direct dermal absorption from the gas phase (as predicted by Kissel et al , for volatile PFAS), or indirect exposure following transformation in the environment to persistent PFAAs. 27 In comparison, PFAAs were readily bioaccessible, indicating that despite occurring at orders of magnitude lower concentrations than listed ingredients, they can nevertheless be relevant for dermal exposure. Clearly, the main limitation in this study was that our SSFL composition did not include sebum, which was previously shown to enhance bioaccessibility, in particular for more hydrophobic PFAS.…”

Cloth–Air Partitioning of Neutral Per- and Polyfluoroalkyl Substances (PFAS) in North Carolina Homes during the Indoor PFAS Assessment (IPA) Campaign

“…Thus, clothing as a secondary PFAS source could potentially facilitate dermal PFAS exposures and prolong indoor inhalation exposures. Generally, dermal absorption of PFAS has been considered a minor route of exposure compared to other pathways, i.e., dietary intake and drinking water, because dermal permeability has been thought to be low for PFAS. ,,,, However, a recent study found that direct transdermal absorption of PFAS from air may be of greater relevance than inhalation exposure for multiple neutral PFAS . Based on the estimates of the dermal uptake-to-inhalation (D/I) ratio reported by Kissel et al and the criteria established by Weschler and Nazaroff, dermal absorption is not expected to exceed inhalation exposure but is expected to contribute non-negligibly to MeFOSE and EtFOSE uptake.…”

“…1,24,48,77,78 However, a recent study found that direct transdermal absorption of PFAS from air may be of greater relevance than inhalation exposure for multiple neutral PFAS. 79 Based on the estimates of the dermal uptake-toinhalation (D/I) ratio reported by Kissel et al 79 and the criteria established by Weschler and Nazaroff, 80 dermal absorption is not expected to exceed inhalation exposure but is expected to contribute non-negligibly to MeFOSE and EtFOSE uptake. Such dermal absorption from air can be mediated by PFAS sorbed to clothing.…”