In vitro percutaneous absorption of [14C] ethylene glycol

The objective of this study was to determine the percutaneous absorption of ethylene glycol through human skin in vitro. The in vitro diffusion cells were of the flow-through design with 1 cm2 surface area. Three separate donor skin samples, taken from the thighs of white males, 16, 37, and 57 years old, were used and three replicates were performed for each experiment. Phosphate buffered saline, at a flow rate of three ml per hour, served as the receptor fluid. The human cadaver skin samples were dermatomed to 500 microns. [14C]-labeled ethylene glycol was applied to the skin surface in acetone vehicle at a dose of 8 micrograms/cm2. After 24-hr dermal exposure, 18.28 +/- 11.66% of the applied dose was recovered in the receptor fluid, 8.29 +/- 5.02% in the skin and 12.53 +/- 6.77% in the skin surface wash (total accountability was 39.11 +/- 7.23%). Individual difference existed (P < 0.05) for the three human skin sources. The combined skin and receptor fluid partitioning resulted in a potential absorbed dose of 26.57% relative to the 8 micrograms/cm2 applied dose for a 24-hr exposure duration. This represents a flux of approximately 2 micrograms/cm2/24 hr or 0.09 micrograms/cm2/hr for ethylene glycol. The maximum flux observed was 2.82%/hr/cm2 or 0.25 micrograms/cm2/hr.