Allergic photocontact dermatitis developed in a patient to a commercial sunscreen preparation containing para-aminobenzoic acid (PABA) in an alcohol base. Photopatch testing showed photosensitivity to PABA. Sensitization could only be detected when PABA was tested in an alcohol vehicle; a photopatch test to PABA in petrolatum was negative.
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C. G. Toby Mathias (1978) studied this question.
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