Time Course Of Dermal Anthracene Absorption Utilizing Intradermal Microdialysis

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants encountered through daily exposures, including smoking, vehicular exhaust, industry sources, and occupational settings, such as firefighting. Inhalation has received greatest attention as a major exposure route, with limited data regarding dermal absorption. PURPOSE: Utilizing the non-carcinogenic PAH, anthracene (ANT), we aimed to assess 1) time course of dermal ANT absorption and 2) effects of local skin temperature on the magnitude of dermal absorption. METHODS: Two intradermal microdialysis (MD) fibers were inserted in 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 1 μl/min. A 2% ANT solution was applied to skin over each MD 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 dialysate sampling. Following baseline, LH were set to 1) 43 °C (Hot, 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: Preliminary data indicate that no ANT was detected in any baseline samples. From 1 h30 to 1 h 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 ppb. Sampling from 4 h to 4 h 15 min, ANT was detected in all samples at the HT site and quantified in one (344.9 ppb). 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 1 h 45 min (8.7 ± 5.7 and 29.2 ± 20.5 CVC%max, P < 0.05) and 4 h 15 min (12.8 ± 8.3 and 42.8 ± 22.3 CVC%max, P < 0.05). CONCLUSIONS: Preliminary data indicate that dermal absorption and recovery of the PAH anthracene is increased when skin is heated versus thermoneutral, increasing over time. This has potential implications for dermal absorption of contaminants in individuals working in the heat. These data also suggest that microdialysis may be an effective method of assessing dermal absorption of PAHs.