TIME COURSE OF DERMAL ANTHRACENE ABSORPTION UTILIZING INTRADERMAL MICRODIALYSIS

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\u3c0.05) and 4h 15min (12.8 ± 8.3 and 42.8 ± 22.3 CVC%max, P\u3c0.05). 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

INTRADERMAL MICRODIALYSIS AS A NOVEL APPROACH FOR DERMAL POLYCYCLIC AROMATIC HYDROCARBON ABSORPTION ASSESSMENT

Roman W. Galaska1, Killian D. Wustrow1, Nelson R. Vinueza2, 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 environmental toxicants produced during incomplete combustion and are linked to adverse health outcomes including cancer. Dermal absorption of PAHs has been minimally investigated due to the complexities of in vivo sampling. Initial in vitro procedures can be developed and optimized before in vivo application to assess skin penetration as an exposure route. PURPOSE: Determine optimal procedures for PAH recovery utilizing microdialysis (MD) for recovery of the non-carcinogenic PAH Anthracene (ANT). METHODS: Initial in vitro testing utilized two different MD fibers (BASi, 30 KDa molecular weight cutoff; CMA, 55 KDa molecular weight cutoff) fully submerged in a 2% ANT solution. ANT recovery was quantified following alterations in the following variables: 1) duration of equilibration time when perfusion pumps were off (10 min, 20 min), 2) concentration of 2-hydroxypropyl-β-cyclodextrin (2β-CD) mixed with lactated Ringer’s used as an excipient (0%, 5%, and 10%), and 3) perfusion rate (1.5 uL/min, 1.0 uL/min, or 0.5 uL/min). MD fibers were submerged in the ANT solution and dialysate samples were collected intermittently. All protocols were repeated in a counterbalanced order. Dialysate samples were analyzed via atmospheric pressure chemical ionization tandem mass spectrometry. RESULTS:No ANT was detected in the CMA fiber samples under any conditions. Greatest ANT concentrations sampled from BASi fibers occurred during the 10 min Equilibration/1.0 ul/min perfusion rate/10% 2β-CD and 10 min Equilibration/0.5 ul/min perfusion rate/10% 2β-CD conditions, reporting 122.6 ppb and 209.0 ppb, respectively. ANT was detected but was lower than the limit of quantification under the 10 min Equilibration/1.0 ul/min perfusion rate/0% 2β-CD and 20 min Equilibration/0.5 ul/min perfusion rate/0% 2β-CD conditions. CONCLUSION: Careful consideration should be given to variables affecting substance recovery utilizing intradermal microdialysis. Under the conditions utilized, optimal procedures for ANT recovery utilized the BASi MD fiber under the 10 min Equilibration/10% 2β-CD with 0.5 ul/min or 1ul/min perfusion rate. Development of procedures for polycyclic aromatic hydrocarbon recovery in vitro using microdialysis are important for in vivo applications for dermal absorption assessment