Asthma occurs 2 to 6 years after contact.
Sensitization occurs during the mixing of the powders.
Colouring agents associated with chromophores act as electrophilic haptens. They are attached to the fibres by strong covalent bonds. Asthma is preceded by rhinitis and is linked with work initially, but becomes permanent. Urticaria and eczma may develop at the same time. Diagnosis References Skin prick test with extracts of the combined colouring agents.