FREQUENCY OF SENSITIZATION TO 13 COMMON PRESERVATIVES IN SWITZERLAND

From February 1989 to January 1990, the Swiss Contact Dermatitis Resea rch Group conducted a 1-year study to examine the frequency of sensiti zation to a series of 13 common preservatives. A group of 2295 consecu tive outpatients with suspected allergic contact dermatitis (age range 7-90 years, with a mean age of 42; 911 males, 1384 females) was teste d. The %s of positive reactions to the preservatives studied are as fo llows, in descending order: formaldehyde 5.7%, benzalkonium chloride 5 .5%, Kathon CG 5.5%, thimerosal 4.2%, chlorhexidine digluconate 2.0%, DMDM hydantoin 1.7%, paraben mix 1.7%, chloroacetamide 1.5%, Bronopol 1.2%, imidazolidinyl urea 1.0%, quaternium 15 1.0%, triclosan 0.8%, 2, 4-dichlorobenzyl alcohol 0.4%. These relatively high values suggest a heavy exposure of the Swiss population to topical preservatives. Compa red to previous studies. the sensitization rate to Kathon CG has stabi lized in Switzerland over the last 2 years. Sensitization to formaldeh yde portrayed impressive geographical variation, with sensitization ra tes up to 9% in western and only 3% in eastern Switzerland. The low se nsitization rate to parabens argues for their inclusion in a medicamen t or preservative series, rather than in the standard series.