Ocular toxicology: the Draize eye test :

A criticism of the use of the rabbit low-volume eye test to determine eye irritation hazard for man is the lack of comparative data in man and rabbit with undiluted products. To address this, such a study has been performed in man and rabbit using undiluted model liquid detergents. The hypothesis tested was that if, under identical test conditions, the effects in the rabbit were the same or greater than the response in man, then it is valid to use the low-volume eye test to assess eye irritation hazard for man. The studies were carried out using 29 human volunteers and 12 rabbits. The effects in the rabbit were unequivocally greater than the effects observed in man, but clearly less than the expected response from these types of product in the Draize test. The results from this study confirm the sensitivity of the rabbit as a test species, and support the use of the low-volume eye test to assess eye irritation hazard for man. Any in vitro/ex vivo alternative to assess eye irritation should be developed against the rabbit low-volume eye test or human data where available.

Arginine-derivative surfactants constitute a novel class of surfactants, which can be regarded as an alternative to conventional surfactants. Prior to human exposure, it is necessary to assess their irritation potential. The classical in vivo evaluation of the irritancy potential via the Draize test has been extensively criticized. In that regard, a great number of in vitro alternatives have been developed. Erythrocytes were chosen as the target cells for eye irritation assessment and hemolysis and hemoglobin denaturation were selected as appropriate endpoints. For skin irritancy assessment, the keratinocyte cell line NCTC 2544 was used and different in vitro endpoints were measured: two cytotoxicity assays (NRU and MTT) and the synthesis of the proinflammatory cytokine IL-1alpha. The eye and skin Draize tests were also performed for comparative purposes. The results point out that, according to in vivo and in vitro assays, the new arginine-derivative surfactants have lower eye and skin irritation potential than the synthetic surfactant SDS. Furthermore, in vitro methods were also able to detect differences in irritancy among the new surfactants not noticeable by the Draize tests, indicating that in vitro methods can be more sensitive than the in vivo test, offering the opportunity to detect subtle differences in irritancy.