Skin absorption in vitro of glycol ethers

Objectives: The increased use of glycol ethers (GEs) for water-based paints and cleaning products, combined with a lack of information about many of t hese products, particularly with regard to the effects of percutaneous expo sure, led us to evaluate the skin absorption rates of a group of glycol eth ers in vitro. Methods: Skin permeation was calculated using the Franz cell method with human skin. A physiological solution was used as the receiving phase. The amount of solvent passing through the skin was analysed with a g as chromatographic technique employing flame ionization detection. A permea tion profile was obtained and steady state, lag time and permeation constan t flux was calculated for each of the following solvents. ethylene glycol m onoethyl ether (EGMEE), propylene glycol monomethyl ether (PGMME); propylen e glycol mono-methyl ether acetate (PGMMEac); 2-propylene glycol 1-butyl et her (2PG1BE), ethylene glycol dimethyl ether (EGDME), ethylene glycol dieth yl ether (EGDEE) and diethylene glycol dimethyl ether (DEGDME). All solvent s were tested in their pure form and with 70% acetone. Results: For all sol vents tested the lag time was less than 2 h: and for the majority of them w as about 60 min. Flux at steady state ranged between 0.017 +/- 0.005 and 3. 435 +/- 1.597 mg/cm(2) and permeation rate was from 0.0192 to 1.02 x 10(-3) cm/h. The presence of acetone in the solution caused a reduction in lag ti me and an increase in permeation rate, higher for EGMEE, lower for EGDEE, i ndicating the enhancing effect of this mixture of solvents. Conclusions: Ou r results confirm the high percutaneous absorption of the GEs tested. The F ranz method might be helpful for obtaining a grading of skin notation for h ydrophilic substances: in the case of glycol ethers, it can give us precise information about permeation risk, particularly important in the evaluatio n of exposure. In the case of solvents with high dermal absorption, the air concentration is no longer a sufficient measure of the total exposure to w orkers, and therefore merely respecting threshold limit values (TLVs) in th e air is not necessarily enough to protect them.