Aetiology

• acute - due to a single exposure or a few brief exposures to a strong irritant or caustic agents (1):
  • commonly, strong acids and alkalis, phenol, halide, quaternary ammonium compounds, organic solvents. Lesions appear rapidly at site of contact
• chronic or cumulative- due to repeated exposure to degreasing or weak irritants with removal of protective lipid film. (1):
  • irritants can be either
  • wet - soaps, detergents, foods, organic solvents, oils, weak acids and alkali
    • continual wetting of the skin without drying leads to evaporation of water, cooling of the skin, cracking of the keratin and penetration of irritant substances, for example in bar workers, fish workers, or in children around the mouth from continual dribbling
  • dry - low-humidity air, heat, powders, paper, cardboard and abrasive dusts (1,2).

Constitutional factors are probably involved since certain patients eg. those with atopic eczema are more susceptible than others.

Reference:

1. Johnston GA et al. British Association of Dermatologists' guidelines for the management of contact dermatitis 2017. Br J Dermatol. 2017;176(2):317-329
2. Bourke J et al. Guidelines for the management of contact dermatitis: an update. BJD 2009; 160:946-954