6 June 2007
In vitro irritancy breakthrough
Four newly validated in vitro/ex vivo irritancy tests for skin and eye have been announced by ECVAM. Two of the tests – using
EPISKIN and Epiderm – will replace the regulatory Draize skin irritation test which was introduced sixty years ago.
EPISKIN and Epiderm use reconstituted human skin in culture to assess a variety of parameters indicative of irritancy. The two skin tests were entered into a formal validation study by ECVAM in 2003 and involved several laboratories in Europe and the USA. The independent validation focused on two endpoints: cell viability and the release of interleukin-1A, which can signal the start of inflammatory processes. The validation addressed both relevance and reproducibility within and between the laboratories using EPISKIN and Epiderm. Both tests will be of immense value as reliable and non-animal based tests of skin irritancy of chemicals and cosmetics throughout Europe, especially for the Registration, Evaluation and Authorisation of Chemicals (REACH) testing programme which came into force in June 2007. ECVAM recommends that the new methods replace all rabbit skin irritancy testing for regulatory purposes.
The second pair of irritancy tests use slaughterhouse material to identify chemicals which might cause eye irritancy. For severe irritants, these methods will replace the Draize eye test, also launched in the 1940s, which depended upon ocular responses in live rabbits. One of the newly validated tests is the Bovine Corneal Opacity and Permeability (BCOP) assay and is based upon a technique which was developed with Trust support [1-4].
Whilst the BCOP assay has taken twenty years to reach trans-European validation it has been used in several European countries, including the UK, to assess potential severe eye irritancy during that time. The second eye test uses isolated chicken eyes (ICE). All four assays are simple, highly reproducible and predictive. They represent humane ways of assessing the safety of novel chemicals.
References
1. Muir CK (1984). A simple method to assess surfactant-induced bovine corneal opacity in vitro: preliminary findings. Toxicology Letters 22:199-203.
2. Muir CK (1985). Opacity of bovine cornea in vitro induced by surfactants and industrial chemicals compared with ocular irritancy in vivo. Toxicology Letters 24:157-162.
3. Muir CK (1987). Qualitative differences in opacification and thickness of bovine cornea in vitro induced by acid, alkali, surfactant or methanol. ATLA 14:279-287.
4. Muir CK (1987). Surfactant-induced opacity of bovine isolated cornea – an epithelial phenomenon. Toxicology Letters 38:51-54.