[Contact allergy to preservatives contained in cosmetics]

The aim of this study was to assay the type of allergy to preservatives contained in cosmetics and to assess the usefulness of the composition of allergens included in a standard series for the diagnosis of occupational contact allergy used to date.

The frequency of contact allergy to the standard series of preservatives (thimerosal, Euxyl K 400, formaldehyde, Kathon CG, Quaternium 15, parabens) was assayed in a group of 1937 subsequent patients referred to the Nofer Institute of Occupational Medicine in L6di and examined in the years 2000-2005. The frequency and type of allergy to preservatives of a cosmetic series in a group of 113 patients with poor tolerance of cosmetics were also investigated.

Allergy to thimerosal was found in 11.8% of patients tested with a standard series; to formaldehyde in 4.9%; and to Euxyl K 400 in 3.7%. Quaternium and parabens were less allergenic (0.8 and 0.3%, respectively). In the group of 113 patients subjected to patch test with a cosmetic series, allergy, i.e. at least one positive patch test, was observed in 49 (43.4%) patients. Of the 27 preservatives contained in cosmetics, 16 induced positive reaction to chemical compounds. Euxyl K 400 proved to be the basic allergenic preservative of this series, and induced allergy in 21 (18.6%) patients, whereas 17.7% of patients reacted to thimerosal. Only allergy to thimerosal applied to 8 persons, and 7 of them showed inflammatory lesions only on the face. Less allergic biocides were cocamidopropyl betaine (7.1%), Kathon CG (7.1%), Bronopol (5.3%), Germall II (4.4%), triethanolamine (3.5%), Germall 115 (2.6%), DMDM hydantoin (2.6%), Grotan BK (1.8%), sodium-2-pyridinethiol-1-oxide (1.8%), clioquinol (0.9%), Quaternium 15 (0.9%), and dimethylaminopropylamine (0.9%).

The results of our study confirmed observations of other authors that allergy to preservatives present in numerous industrial products, especially Euxyl K 400, is still a growing problem. Like many other researchers, we are of the opinion that this allergen should be included in a standard series for the diagnosis of all patients with suspected allergic dermatitis, including that of occupational origin.