The use of a microporous membrane as an interface between a cell culture and a substance dissolved into a non-aqueous, non-cytotoxic medium made it possible to study the cytotoxicity of non-hydrosoluble substances, without addition of any adjuvant for dispersion or solubilisation. The LC50s of raw materials widely used in cosmetic and pharmaceutical products were established on skin human fibroblasts. This method was used for the study of cosmetics and toiletries which could be tested directly in their actual galenic forms. A relationship between exposure time and cytotoxicity was established for 50 products and a cytotoxicity index was calculated. The results were compared with those of the Draize irritation test on the rabbit eye. This comparison showed a very good correlation between the calculated cytotoxicity index and the ocular irritation index (p < 0.001). From the results of this preliminary study, it appears that the method could provide an alternative to animal studies on the ocular tolerance of cosmetics and toiletries.
Synopsis The ocular irritation potential of 107 cosmetics and toiletries was compared using the rabbit's eye Draize test (IOMA), a cytotoxicity in vitro method (CFIO), and the hen's egg chorioallantoic membrane test (HET-CAM). There was a good correlation between both alternative methods and the Draize test. Non-correlating results were observed in 12 cases with the HET-CAM method (six false positives, two false negatives, four technical failures) and in 14 cases with the CFIO method (ten false positives, four false negatives). However, all clearly irritant products were detected. False negatives were only found in products whose ocular irritation index lay close to the boundary (IOMA = 15) between the slightly and the moderately irritant products. None of the products was falsely found to be negative by both alternative methods. Therefore, the risk of underestimating the ocular irritation potential was avoided. The coupling of these two methods seemed to be of interest as an alternative approach to the assessment of the potential for ocular irritation of cosmetics and toiletries.
The use of a microporous membrane as an interface between the cell monolayer and a substance dissolved in a non-aqueous, non-cytotoxic medium has permitted the study of the cytotoxicity of non water-soluble substances without the addition of any adjuvant for dispersion or solubilisation. The LC50 values of raw materials widely used in cosmetic and pharmaceutical products were established on human skin fibroblasts. This method was also applied to the study of cosmetic products. A relationship between exposure time and cytotoxicity was established for 169 products and a cytotoxicity index (MCI) was calculated. When the results were compared to the Draize maximal ocular irritation index (MaOI), a very good correlation was shown between MCI and MaOI.
