Primary irritant patch-test reactions in children.

Abstract

Nickel sulphate and formaldehyde in dilutions nonirritant to the adult person, give a high percentage of primary irritant reactions in children. The intradermal test is negative. The percentage of reactions declines with increasing age, disappearing in the seventh-eighth year. The reactions are follicular and/ or eczematous and are often accepted as positive allergic reactions. They may be repeated at brief intervals but not at longer intervals. Reactions to nickel sulphate and formaldehyde show several numerical differences, possibly due to the different chemical properties of the test substances. The findings indicate an epithelial barrier factor varying in the age group 0-8 years. A related phenomenon is known from the results of tuberculin testing. Patch tests on children require dilutions of allergens weaker than those used for adults, e.g., nickel sulphate 1%, formaldehyde less than 1%.