They act as direct histamine liberators in vitro. The combination of exposure to irritants and allergens in a work place which is typically poorly ventilated, without extractor fan, is the main source of the problem. The persulfates which are used in bleaching have been proved statistically to be the major cause. In factories producing persulfates, it has been shown that levels inferior to 1 mg per m2 of air protects against sensitization. The first symptom is rhinitis which occurs within minutes of contact.
Classic asthma linked to work is often also present.
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.