The Action Spectrum of Photocontact Dermatitis

Nineteen patients with clinical features of a photocontact dermatitis by photopatch testing were proved to be sensitive to tetrachlorosalicylanilide, dibromsalan, metabromsalan, tribromsalan, hexachlorophene, bithionol, or triclocarban. The most common clinical findings were a lichenoid dermatitis of exposed skin of the hands, arms, face, and neck. Erythematous and eczematous reactions were also observed. Using a high intensity monochromator, action spectra delineated for tetrachlorosalicylanilide, dibromsalan, hexachlorophene, and bithionol revealed the effective wavelengths to be between 300 and 425 nanometer (nm). The shorter wavelengths were usually slightly more efficient in eliciting a threshold response. In one patient sensitive to triclocarban, no reactions were elicited with wavelengths longer than 360 nm.