Dristen D. Trate1, Killian D. Wustrow1, Nelson R. Vineuza2, Xinyi Sui2, Morgan Demmler2, Emiel A. DenHartog2, Scott R. Collier, FACSM1, Caroline J. Smith, FACSM1. 1Appalachian State University, Boone, NC. 2North Carolina State University, Raleigh, NC.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants frequently encountered through common daily occurrences, including smoking, vehicular exhaust, and industry sources, as well as occupational settings, such as firefighting. While inhalation is typically assessed as a major exposure route, limited data are available regarding dermal PAH absorption. PURPOSE: Utilizing the non-carcinogenic PAH, anthracene (ANT), we aimed to assess 1) the time course of dermal ANT absorption and 2) the effects of local skin temperature on the magnitude of dermal absorption. METHODS: Intradermal microdialysis (MD) fibers were inserted at two sites on the ventral forearm of 6 healthy participants (32 ± 5 yrs, 5 male, 1 female). MD fibers were perfused with 10% 2-hydroxypropyl-β-cyclodextrin with lactated Ringer’s at a rate of 1 ul/min. A 2% ANT solution was applied to the skin over each site with overlying local heaters (LH) housing laser Doppler flowmeters for assessment of skin blood flow (SkBf). LH were clamped at 33°C during baseline SkBf and dialysate sampling. Following baseline, LH were set to 1) 43°C (Hot site, HT) and 2) 33°C as thermoneutral (TN) for the duration of the protocol. Dialysate samples were collected intermittently over 4 hours and 15 minutes, and SkBf, blood pressure and HR were recorded throughout the protocol. Atmospheric pressure chemical ionization tandem mass spectrometry was used to quantify ANT dialysate concentrations. RESULTS: No ANT was present in any baseline samples. From 1h30 to 1h 45 min, ANT was detected in 3 of 6 and 0 of 6 samples for the HT and TN sites, respectively. One HT sample was quantifiable at 317.5 ppm. Sampling from 4h to 4h 15 min, ANT was detected in all samples at the HT site and quantified in one (344.9 ppm). ANT was detected in only 1 of 6 samples at the TN site during this sampling period. SkBf was significantly higher at HT versus TN at both 1h 45 min (8.7 ± 5.7 and 29.2 ± 20.5 CVC%max, P<0.05) and 4h 15min (12.8 ± 8.3 and 42.8 ± 22.3 CVC%max, P<0.05). CONCLUSIONS: Dermal absorption of the PAH anthracene is increased when skin in heated versus thermoneutral conditions. Anthracene recovery is increased during longer periods of exposure when the skin is heated. This has important implications for individuals working and exercising in the heat. This data also suggests that microdialysis may be an effective method of assessing dermal absorption of PAHs.

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