[Occupational asthma: methods of diagnosis and principle etiologies]

The diagnosis of occupational asthma requires the integration of a multiplicity of data; the history, cutaneous skin tests, respiratory function tests and non-specific tests of bronchial hyper-reactivity and specific bronchial provocation tests. The history remains fundamental in the investigation of occupational asthma. It should particularly search for the presence of an atopic trait, the occurrence of similar disorders in members of the same firm and also the timing of symptoms in relation to the occupational activities. Cutaneous tests are particularly helpful in IgE-mediated asthma in relation to the inhalation of animal or vegetable materials of glycoprotein origin. For haptens, the need for their prior coupling to a protein carrier causes problems which have not been entirely resolved. Laboratory tests (RAST, histamine liberation, TDBH...) run into the same snags. Respiratory function and non specific bronchial provocation tests confirm the diagnosis of asthma and enable the medium and long term progress to be assessed. Specific bronchial provocation tests are the most appropriate tests to establish an aetiological diagnosis in occupational asthma. Different technical methods are possible: quantitative administration of allergen, aerosols, and realistic tests using exposure chambers to achieve true test doses and to obtain dose dependent responses. The products responsible for occupational asthma are multiple and are gathered into two tables. The different substances are characterised in a simplified manner. First animal matter (mammalian and arthropod allergens), secondly substances of vegetable origin (roots, leaves, flowers, grain and flour, wood and its derivatives) and finally chemical products. The chemical products are primarily from the pharmaceutical and metal industries and above all from the plastics industry.