Twenty-five years quaternium-15 in the European baseline series:does it deserve its place there?

For allergens to be included in the European baseline series, they should have allergy rates of at least 1%. In several studies quaternium-15 had lower scores. Also, many cases of sensitization are already detected by formaldehyde contact allergy. The aim of this study was to evaluate whether quaternium-15 deserves continued inclusion in the baseline series on the basis of current criteria: 1% positive reactions, common occurrence in the environment, many relevant reactions. We used the literature survey method in this study. Only the United Kingdom has rates consistently over 1%. The mean for all other countries together and for many individual nations is lower than 1%. At least half of the reactions are already detected by formaldehyde sensitivity, which lowers rates for allergy to quaternium-15 per se (i.e. not caused or at least detected by formaldehyde sensitivity) to less than 0.6% for all countries except the United Kingdom. Neither common occurrence in the environment nor a high percentage of relevant reactions has been ascertained. It may well be argued that quaternium-15 does not deserve its place in the European baseline series and could be incorporated in a cosmetic screening series or preservative series instead. In the United Kingdom, routine testing should be continued.</p

Relationship between formaldehyde and quaternium-15 contact allergy. Influence of strength of patch test reactions

Objectives: To test our hypothesis that patients with stronger patch test reactions to formaldehyde are more likely to react to quaternium-15, attesting to the aetiological role for formaldehyde in such co-reactivity. Methods: Retrospective analysis of all patients patch tested with formaldehyde and quaternium-15 in the European baseline series between 1994 and 2009 (TRUE test (R)). Results: In a group of 86 patients allergic to formaldehyde, 73% co-reacted to quaternium-15; in the subgroup of 70 women, the percentage was 83. In both groups, more reactions were observed to quaternium-15 in the patients with a ++ reaction compared to the patients with a + reaction to formaldehyde. Conversely, stronger reactions to quaternium-15 were significantly more often associated with formaldehyde sensitivity in a group of 107 patients reacting to quaternium-15 and a subgroup of 88 women. In men, such effects were not observed and only 5 of 16 (31%) men allergic to formaldehyde also reacted to quaternium-15. Conclusions: In women, but not in men, stronger reactions to formaldehyde lead to more positive quaternium-15 patch tests