Monteiro-Riviere, N.A., R.E. Baynes, G.L. Qiao, and J.E. Riviere. Cutaneous Toxicity of the Benzidine Dye Direct Red 28 Applied As A Mechanistically-Defined Chemical Mixture (MDCM) in Perfused Porcine Skin. The Toxicologist 1997. 36: 188.

sodium lauryl sulfate - 00151-21-3; methyl nicotinate - 00093-60-7; stannous chloride - 10025-69-1

Dermal exposure to chemical mixtures rather than to single chemicals is a more likely scenario at hazardous waste sites. These mixtures can potentially consist of a marker chemical and several other chemicals, each of which can have different mechanistic actions on dermatotoxicity and dermal absorption of the marker chemical and/or other components in the mixture. Sixteen mixtures, consisting of a marker chemical direct red 28 (DR28), a solvent (acetone or DMSO), a surfactant (0 or 10% sodium lauryl sulfate, SLS), a vasodilator (0 or 180 ug methyl nicotinate, MN), and a reducing agent (0 or 2% SNCl₂) were selected. Isolated perfused porcine skin flaps (IPPSF), which have been proven to be an in vitro model for assessing absorption and toxicity, were utilized. Perfusate samples were collected for 8 hrs and skin was obtained for microscopic evaluation. Although no DR28 was absorbed, light microscopic observations depicted minor alterations (intra- and intercellular epidermal edema) with DMSO mixtures than with acetone mixtures. DMSO mixtures containing SLS + MN caused a greater increase in epidermal edema than other mixtures. Acetone mixtures containing SLS, SnCl₂, or SLS + SnCl₂ were least likely to cause epidermal edema. The presence of SLS in any mixture produced an alteration in the stratum corneum. In conclusion, this study demonstrated that various mixtures alter the epidermal barrier differently with complex interactions evident. This is important not only because of the chemical-induced alterations to skin but this could influence the transdermal flux of toxic components in topically applied mixtures. This research was supported by NIEHS 00044.