Changing trends in the epidemiology of contact dermatitis in Singapore

All patients seen in the Contact Dermatitis Clinic of the National Skin Centre, Singapore (and the former Middle Road Hospital) between January 1986 and December 1990 were analysed retrospectively. 5557 patients comprising 2634 (47.4%) males and 2923 (52.6%) females were patch tested. 3154 (56.8%) patients had 1 or more positive reactions. The majority of the patients were Chinese (78.0%), followed by Malays (11.5%), Indians (8.1%) and other minority races (2.4%). The majority of positive reactions belonged to the 21-40 age group. The incidence of positivity decreased after 60 years. The commonest allergens responsible were nickel (17.7%), fragrance (13.3%), neomycin (6.9%), colophony (6.6%) and proflavine (6.5%). Both neomycin and proflavine were commonly used as over-the-counter medicaments. Compared to an earlier report in 1988, there were differences in the incidence of contact sensitivity to some allergens. Potassium dichromate, which used to be a common allergen, was less common. Some allergens (carba-mix, naphthyl-mix, caine-mix and PCMX) have been removed from our standard series as they were uncommon causes of contact allergy. Thimerosal and Amerchol L-101 were added in their place.