The agarose diffusion method for ocular irritancy screening: cosmetic products, part i

Abstract

The cosmetics industry is the target of criticism from animal welfare and animal rights groups for its use of the Draize eye irritancy test to substantiate the safety of cosmetic ingredients and products. To date, the two main difficulties in the development of alternatives to the Draize test have been a lack of high correlation between in vitro alternative test results and in vivo Draize test results, and the inability to present typical cosmetic formulations to these alternative test systems. For these reasons it occurred to us to test cosmetic products with the agarose diffusion test. This test has been scientifically validated and is well-established as an in vitro alternative test to screen the toxicity of plastics in medical devices. Sixteen cosmetic products initially tested with the Draize eye irritancy test and skin irritation test were tested in the agarose diffusion method to determine whether zone of lysis and/or cell toxicity could be correlated with either Draize eye test results or primary irritation index (PII). Even though the sample size was small (16 cosmetic products exclusive of controls), 80% (4/5) of the samples positive in the Draize eye test were predicted by the agarose diffusion method. Eighty-two percent (9/11) of the Draize negative samples were predicted by this same method, for an overall correlation of 81 % between the agarose diffusion method and the results in the Draize eye irritancy test. Only 19% of the test materials were false positives (2/16) or false negatives (1/16), suggesting that the agarose diffusion model may be slightly more sensitive than the Draize eye method. No correlation between the agarose diffusion test and the primary skin irritation test results could be established. These results indicate a high degree of correlation between an in vitro screening test as an alternative to the Draize eye irritancy test and permit testing of oil-in-water emulsions (both pigmented and nonpigmented), water-based suspensions, petroleum-distillate-based suspensions, solutions, physical mixtures of waxes, and physical mixtures of dry powders in this alternative test system.