It is well known that eczematous skin reactions can be produced either by a primarily irritating substance or by an allergen. It will be the purpose of this paper to discuss the nature of the two types of eczematous reactions and their interrelations.
An eczematous allergen is defined as a substance that is not primarily irritating on first exposure but which, in persons of the appropriate genetic constitution, causes the development of an allergic sensitization of the delayed type, so that subsequent contact with concentrations that are nonirritating to unexposed or nonsensitized persons produces an eczematous reaction. A primary eczematous irritant is defined as a substance which produces an eczematous response by nonimmunologic means. Primary irritants may be divided into two categories: (1) immediate, and (2) cumulative. An immediate primary irritant is the usual type. Here the eczematous reaction is produced on first exposure. The
ROSTENBERG A. Primary Irritant and Allergic Eczematous ReactionsTheir Interrelations. AMA Arch Derm. 1957;75(4):547–558. doi:10.1001/archderm.1957.01550160073009