Koschier, F.J., R.N. Roth, K.A. Wallace, R.D. Curren, and J.W. Harbell. A Comparison of Three-Dimensional Human Skin Models to Evaluate the Dermal Irritation of Selected Petroleum Products. In Vitro Toxicol. 1997. 10(4): 391-405.

petroleum products

The in vitro evaluation of the dermal irritation potential of volatile or water insoluble petroleum products has generally proved difficult. We attempted to overcome these difficulties by utilizing three commercially supplied human skin constructs to assess the dermal irritation potential of 14 petroleum refinery streams. Tissues were treated with the neat test materials for periods of up to 24 hours. Certain modifications to the standard dosing procedures were developed to address the solvent and volatile nature of the test materials. Four end points were assessed at each exposure time. Culture medium under the tissue was sampled for lactate dehydrogenase (LDH), interleukin-1-alpha (IL-1a ), and prostaglandin E₂ (PGE₂) concentrations. The ET₅₀ (time to reduce the MTT conversion to 50% of time-matched controls) was calculated for each test material in each system. In general, the ET₅₀ times for all three skin models ranked many of the 14[10 for living skin equivalent (LSE)] test materials similarly. Spearman rank order analysis comparing the in vitro cytotoxicity data with the Primary Dermal Irritation Index (PDII) scores gave values of 0.54 (LSE), 0.41 (ZK1300), and 0.79 (EpiDerm). The Actual ET₅₀s of the more irritating materials varied between the three systems with the ZK1300 system appearing to show the greatest toxicity. LDH release in the three systems corroborated cytotoxicity estimated by the MTT₅₀. Cytokine levels were normalized to the amount produced at the ET₅₀ time point. These data indicated that IL-1a concentrations showed reasonable correlations with the known in vivo irritation level, especially in the EpiDerm cultures. It appeared that for all three models the best prediction of in vivo irritation came from a combination of cytotoxicity and IL-1a release measurements. Materials that had very low in vivo irritancy (PDII £ 1.5) generally had MTT₅₀ values of >24 hours and released no measurable IL-1a . Materials with moderate in vivo irritancy level (1.5 > PDII < 4.0) had MTT₅₀ values of >24 hours but did show some induction of IL-1a . Materials with higher irritancy (PDII ³ 4.0) generally caused both cytotoxicity and cytokine release.