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| High standard deviation and variation coefficients in the "Golden Standard" for eye irritation |
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This graphic shows an analysis of the Draize tests, within a number of the quality criteria which are required, for the validation of alternative methods (The Report and Recommendations of ECVAM Workshop 5; ATLA 23, 129-147, 1995). The Validations Criteria are set in Europe by the ECVAM, which will be shown in greater detail on a later page.
The quality analysis shown here is limited to the 20 substances, whose Draize data has been officially recorded (ECETOC* Technical Report No. 48(2) 1998) and which will also be used for the validation of the alternative methods which are here introduced.
In the left hand picture, it can be seen, that the standard deviation for moderate irritative substances is very high; also important for the R36 classification, MAS of 25 lies within this range.
For mathematical reasons the % variations co-efficient (%CV=Coefficient of Variance) is not only in this area very high (see picture on the right), but also for other substances with a very low potential for irritation. An alternative test is considered as acceptable for the ECVAM, when a %CV of under 30 is achieved and that is over the widest possible area of the irritation potential. An exceeding of the CV, resulting only from chemicals with a low irritative potential would still be acceptable (small variations, purely mathematically lead very quickly to large %CV values). In the example chosen these quality criteria are only fulfilled by the Draize test within partial areas.
*ecetoc = European Centre for Ecotoxicology and Toxcology of Chemicals
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ECETOX