Urticaria and facial oedema are common symptoms and eczema has also been reported. Eczema of the hands is also very common. Delayed reactions are possible with bronchial provocation test. A cross sectional study of chemical industry workers with occupational exposure to persulphates. Occupational asthma caused by black henna.
Isocyanates are direct irritants to the respiratory tract.
Their toxicity can result in fatality. Atopy does not play a predisposing role. Immunological mechanisms involving the anti-bodies IgE and IgG have been demonstrated. Other mechanisms involving bronchial beta-receptors or the inhibition of cholinesterase have also been suggested. Bronchial response can be either immediate or delayed.