METHODS - Base-line measurements included a questionnaire on personal characteristics and anamnestic information, examination of hand skin, measurements of transepidermal water loss, patch tests, and prick tests. The condition of the hands, previous exposure, and transepidermal water loss were followed at intervals of four to six weeks. Cox proportional hazard models were used in the statistical analysis.

RESULTS - The average incidence rate of hand dermatitis was 32.8 cases per 100 person-years for the hairdressers and 14.5 cases per 100 person-years for the nurses. The rate ratio of having a dry versus normal skin type was 7.3 for the hairdressers [95% confidence interval (95% CI) 2.2-24-3] and 1.7 for the nurses (95% CI 0.5-6.4). Apprentice nurses with a history of (atopic) mucosal symptoms had a 3.4-fold increased incidence rate of hand dermatitis (95% CI 1.05-11.2). The rate ratio of mucosal atopy for the apprentice hairdressers was 2.2 (95% CI 0.7-6.7). Graphic display of the results suggested an increased risk of hand dermatitis among the apprentice hairdressers with transepidermal water loss on the hand greater than 15 g . m-2 . h, but the relative risk of increased transepidermal water loss was not statistically significant.

CONCLUSIONS - The most important endogenous risk factors for hand dermatitis among the apprentice hairdressers and nurses were the presence of dry skin and a history of mucosal atopy. No relationship between increased transepidermal water loss and the risk of hand dermatitis was observed.