Dermatitis and other skin disorders

Trends in incidence

Statistics based on reports of occupational skin disease within the THOR scheme are affected by various factors including the number and type of participating specialist and occupational physicians, their reporting habits, and by seasonal effects associated with the time of year they report. This makes assessment of trends based on total annual estimated cases problematic since these factors - as well as the true incidence - can vary over time. However, statistical modelling by the University of Manchester showed statistically significant downward trends in the incidence of both contact dermatitis and all skin disease cases over the period 1999-2008 after taking account of some of these effects.

For contact dermatitis a stronger downward trend was evident within the OPRA scheme suggesting a larger reduction in incidence among workers who have access of occupational physicians. The analyses do not take account of a possible tendency for reporters to include fewer cases than they should once they have been reporting for some time (so called "reporting fatigue"). If the data were affected by reporting fatigue this would tend to reduce any observed downward trends. Annual estimated cases of contact dermatitis based on the THOR scheme are shown in Figure 1 below.

The number of assessed cases of occupational dermatitis within the IIDB scheme has declined steadily over the period shown in Figure 1. In the early 1990s there were over 400 assessed cases each year compared with fewer than 200 cases in each of the last five years.

Figure 1: Occupational contact dermatitis