Quantitative assessment of irritation in the mouse skin test.

Intracutaneous injection of aqueous solutions of topically irritant substances into the skin of juvenile mice creates a persisting oedema, the strength of which can be assessed by the number of wrinkles formed on reefing the skin at the site of injection. An algorithm is used to transform the number of wrinkles, recorded just before and 2.5 and 6 hr after the injection, into the intensity of the oedematous reaction. This quantity, which does not depend on subjective assessments graded on an arbitrary scale, is reproducible and has been judged to be relevant to the prediction of irritancy likely to arise from accidental contact of substances with mucous membranes.