PATCH TESTING WITH PRESERVATIVES AT ST-JOHNS FROM 1982 TO 1993

We have reviewed our patch test results for preservative allergy from 1982 to 1993. 8 preservatives were included: formaldehyde, 2-bromo-2-nitropropane-1,3-diol (Bronopol(TM)), quaternium-15 (Dowicil 200(TM)), imidazolidinyl urea (Germall 115(TM)), diazolidinyl urea (Germall II(TM)), parabens, 5-chloro-2-methyl-isothiazolin-3-one plus 2-methyl-isothiazolin-3-one (Kathon CG(TM)) and 1,2-dibromo-2,4-dicyanobutane (one of the constituents of Euxyl K 400(TM)). Whereas the allergy rate to formaldehyde is quite stable, there is a slight increase in the imidazolidinyl urea allergy rate. Quaternium-15's rate is decreasing and 5-chloro-2-methyl-isothiazolin-3-one plus 2-methyl-isothiazolin-3-one's rate, after a rapid rise, seems to have stabilized. Although very important constituents of cosmetics, preservatives not only induce allergies on the face but also on the hands, and, as expected, the allergy rate in men and women generally differs. Among the 5 formaldehyde-releasers, there are some favoured simultaneous reactions: quaternium-15 and formaldehyde, and diazolidinyl urea and imidazolidinyl urea. Concomitant reactions between 1-bromo-2-nitropropane-1,3-diol and formaldehyde are not common, and those between 2-bromo-2-nitropropane-1,3-diol and diazolidinyl urea or imidazolidinyl urea very uncommon. Concomitant reactions between imidazolidinyl urea, diazolidinyl urea, and formaldehyde are not very common. This supports the hypothesis that allergic reactions to the Germalls are directed toward the initial molecule rather than to formaldehyde.