Abstract
Background
Preservatives are indispensable agents used to prevent bacterial and fungal contamination of cosmetics, personal care products, domestic preparations, and industrial products.
Objective
We evaluated patch-test data at the National Skin Centre, Singapore, from 2006 to 2011 to identify the trends in preservative contact allergies.
Methods
All patients with suspected contact dermatitis were patch tested to 4 preservatives within the modified European standard series. Patients were also tested with 7 preservatives from our special series if clinically indicated.
Results
Three thousand one hundred seventy-seven patients were tested to preservatives in the standard series. Sensitization frequencies were all greater than 1%: parabens (2.58%), methylchloroisothiazolinone/methylisothiazolinone (1.75%), quaternium 15 (1.43%), and methyldibromoglutaronitrile (1.2%). There was no change in trends in sensitization frequencies from 2006 to 2011, with no increase in sensitization frequency to methylchloroisothiazolinone/methylisothiazolinone. The sensitization frequencies for methyldibromoglutaronitrile/phenoxyethanol and diazolidinylurea were 2.03% and 1.37%, respectively, and remained less than 1% for bronopol, imidazolidinyl urea, and 2-phenoxyethanol. A rate of 0% was seen for 1,3-dimethylol-5,5-dimethyl hydantoin and formaldehyde; 9.4% of positive patch-test results became positive only at day 7.
Conclusions
Preservatives are common causes of allergic contact dermatitis. This should be considered when introducing new preservatives into the market. Day 7 readings are important to detect late reactions.
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