Per- and polyfluoroalkyl substances (PFAS) in river discharge: Modeling loads upstream and downstream of a PFAS manufacturing plant in the Cape Fear watershed, North Carolina.

The Cape Fear River is an important source of drinking water in North Carolina, and many drinking water intakes in the watershed are affected by per- and polyfluoroalkyl substances (PFAS). We quantified PFAS concentrations and loads in river water upstream and downstream of a PFAS manufacturing plant that has been producing PFAS since 1980. River samples collected from September 2018 to February 2021 were analyzed for 13 PFAS at the upstream station and 43-57 PFAS downstream near Wilmington. Frequent PFAS sampling (daily to weekly) was conducted close to gauging stations (critical to load estimation), and near major drinking water intakes (relevant to human exposure). Perfluoroalkyl acids dominated upstream while fluoroethers associated with the plant made up about 47% on average of the detected PFAS downstream. Near Wilmington, Σ43PFAS concentration averaged 143 ng/L (range 40-377) and Σ43PFAS load averaged 3440 g/day (range 459-17,300), with 17-88% originating from the PFAS plant. LOADEST was a useful tool in quantifying individual and total quantified PFAS loads downstream, however, its use was limited at the upstream station where PFAS levels in the river were affected by variable inputs from a wastewater treatment plant. Long-term monitoring of PFAS concentrations is warranted, especially at the downstream station. Results suggest a slight downward trend in PFAS levels downstream, as indicated by a decrease in flow-weighted mean concentrations and the best-fitting LOADEST model. However, despite the cessation of PFAS process wastewater discharge from the plant in November 2017, and the phase-out of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in North America, both fluoroethers and legacy PFAS continue to reach the river in significant quantities, reflecting groundwater discharge to the river and other continuing inputs. Persistence of PFAS in surface water and drinking water supplies suggests that up to 1.5 million people in the Cape Fear watershed might be exposed.

Measurement of skin surface biomakers by Transdermal Analyses Patch following different in vivo models of irritation: a pilot study.

BACKGROUND/PURPOSE: FibroTx Transdermal Analyses Patch (TAP) is a novel technology for non-invasive measurements of protein biomarkers on the skin surface, in vivo. The aim of this study was to explore the potential of TAP in detecting skin surface biomarkers following mild perturbations, in vivo, using two experimental models: tape stripping, mimicking acute barrier disruption, and histamine iontophoresis, mimicking acute and local inflammation at minimal skin barrier insult. METHODS: Tape stripping and histamine iontophoresis were performed in two separate experiments on the volar forearm of healthy volunteers (n = 27 and n = 10, respectively). Biomarker levels were assessed with TAP at baseline and up to 72 h after stimulation. Functional (transepidermal water loss -TEWL- and a* value) and morphological (confocal reflectance microscopy -RCM) assessments were added in the tape stripping and histamine iontophoresis experiments, respectively. RESULTS: Cytokines IL-1α and IL-1RA and the antimicrobial peptide hBD-1 showed distinct dynamics, despite substantial inter-individual variation in levels, with an increase following tape stripping and a decrease following histamine iontophoresis. These dynamics could be related to the assessments made by TEWL and RCM. In the tape stripping experiment, additional biomarkers could be detected. CONCLUSION: TAP measurements, especially IL-1α, IL-1RA, and hBD-1, from the skin surface were sensitive enough for monitoring dynamic changes in the skin in the two models of skin perturbation. We conclude that TAP holds promise for non-invasively unraveling the dynamics of processes related to skin perturbation and repair.