Wet-work Exposure: A Main Risk Factor for Occupational Hand Dermatitis

Occupational contact dermatitis (OCD) ranks first of all occupational diseases in many countries. The incidence rate is believed to be around 0.5-1.9 cases per 1000 full-time workers per year. Epidemiological studies play an important role in observing disease trends, analysing risk factors, and monitoring the effect of preventive measures. In this review article the lack of truly epidemiologic data on OCD and the difficulties of those studies are illustrated. The following issues are highlighted: case ascertainment and bias, the distribution of allergic and irritant contact dermatitis in the working population, the interrelationship between exogenous (allergens, irritants) and endogenous factors, the prognosis, the social and economic impact, and the need for intervention studies.

Using transmission and cryo-scanning electron microscopy, we confirm that extended water exposure leads to extensive disruption of stratum corneum intercellular lipid lamellae. We define the in vivo swelling behavior of the stratum corneum: exposure to water for 4 or 24 h results in a 3- or 4-fold expansion of the stratum corneum thickness, respectively. Corneocytes swell uniformly with the exception of the outermost and inner two to four corneocyte layers, which swell less. We show that hydration induces large pools of water in the intercellular space, pools that can exceed the size of water-swollen corneocytes. By 4 h of water exposure there are numerous small and large intercellular pools of water ("cisternae") present throughout the stratum corneum, and at 24 h these cisternae substantially increase in size. Within cisternae the lipid structure is disrupted by lamellar delamination ("roll-up"). Cisternae appear to be disk-shaped structures that do not obviously communicate. Cisternae appear to contain considerable lipidic and other material and to contain a substantial fluid volume that can rival the volume of the dry stratum corneum. Similar results are obtained following urine exposure. With urine exposure, cisternae communicate with salts in the external solution. This study illustrates the disruptive effect of overhydration on the stratum corneum intercellular space, identifies large and numerous unanticipated intercellular cisternal structures, defines the magnitude of stratum corneum swelling, and identifies stratum corneum cell layers that swell less. The study suggests the stratum corneum is a more chaotic structure than previously envisioned, and provides a framework for better understanding desquamation, irritancy, and percutaneous transport.

By means of a multivariate regression analysis, we have studied the importance of atopy, "wet" and "dry" occupations, and domestic work as risk factors for hand eczema. Hand eczema was identified by questionnaire. The studied cohort consisted of 2452 newly employed hospital workers with a median follow-up time of 20 months. Of the total cohort studied, 86% were female. The total occurrence of hand eczema in the 4 occupational groups studied were: nursing staff 41%, kitchen workers/cleaners 37%, office workers 25% and caretakers/craftsmen 17%. Atopic dermatitis increased the odds of developing hand eczema by 3 times in wet as well as in dry work. Subjects with atopic dermatitis developed a more severe hand eczema than subjects with atopic mucosal symptoms and non-atopics. Wet hospital work increased the odds by a factor of 2 compared to dry office work. 2 anamnestically available parameters of domestic work, namely "nursing of children younger than 4 years" and "absence of dish-washing machine" were found to significantly increase the risk of developing hand eczema. Wet work in combination with unfavourable domestic factors increased the odds by a factor of 4. The caretakers/craftsmen group, which was dominated by men, showed the lowest figure for hand eczema.