This investigation was subsequently extended by LeCoulant et al. Mitchell et al. Contact dermatitis from Frullania species affects the exposed skin surfaces of forest workers. We have not commonly seen the involvement of the genital region which was emphasised by LeCoulant et al. Differences in climate and hence in habits of dress may explain the varied distribution patterns.
Canadian workers wear rainwear suitable for a cold and wet climate.
Workers may become sensitised after only a few weeks or after many years in forest-work. The dermatitis appears within a day or two of contacting vegetation and clears within a few weeks after leaving such work. Attacks are more severe in wet weather and widespread dermatitis can occur if the clothing is wetted by rain. Weakly sensitised workers can usually continue in forest work, but recurrent dermatitis occurs. Strongly sensitised workers are obliged to leave forest work.