Permanent wave contact dermatitis: contact allergy to glyceryl monothioglycolate.

Eight hairdressers and four clients were found to be allergic to glyceryl monothioglycolate (GMTG) contained in "acid" permanent waves used in American beauty salons only since 1973. Previous studies in Germany showed that compounds closely related to GMTG were strong sensitizers. In contrast, ammonium thioglycolate (ATG) has been used since 1943 in cold "alkaline" permanent waves both in homes and in salons with no clearly documented cases of contact allergy. Our allergic patients reacted to GMTG in concentrations as low as 0.25%, although their exposure in practice could reach concentrations of 20% to 80%. GMTG-allergic patients reacted to GMTG when it was tested through a variety of glove fabrics. Household-weight neoprene gloves were protective.