Comparison of A1-test and Finn chamber test.

A comparison of the A1-test and the chamber test was made by performing epicutaneous tests simultaneously with both methods in symmetrical sites on the upper back. Irritant reactions were provoked with 1.5% benzalkonium chloride on 90 patients. Allergic reactions were studied with 10 allergens on 510 patients; 243 of them gave positive reactions to one or more of the test substances. It was found that the results obtained by these methods were about the same when the A1-test was fixed with nonporous occlusive plaster (Leukoplast). By fixing the A1-test units like the chambers with a porous tape (Scanpor), the chamber test produced more irritant and allergic reactions than the A1-test.