What causes occupational asthma?There are many agents in the workplace that can cause occupational asthma. More than 240 causes of occupational
asthma have been identified. Most commonly, these include protein molecules (wood dust, grain dust, animal dander, fungi) or other chemicals (especially di-isocyanates). Chemical dusts or vapors from plasticizers, polyurethane paints, insulation, foam mattresses and upholstery, and packaging materials used in manufacturing and processing operations. Among specific chemicals known to cause asthma are the isocyanates, trimellitic anhydride, and phthalic anhydride. Animal substances such as hair, dander, mites, small insects, bacterial or protein dusts. Exposed workers at special risk include farmers, animal handlers, shepherds, grooms, jockeys, veterinarians, and kennel workers. Wood products such as western red cedar, some pine and birch woods, and mahogany used by woodworkers and some farm workers; pine resin used in electrical devices. Organic dusts such as flour, cereals, grains, coffee and tea dust, papain dust from meat tenderizer. These substances can cause asthma in millers, bakers, and other food processors. Cotton, flax, and hemp dust inhaled by workers in cotton processing and textile industries. Metals such as platinum, chromium, nickel sulfate, and soldering fumes, Workers are exposed in refining and manufacturing operations.Though the actual rate of occurrence of occupational asthma is unknown, it is suspected to cause between 2 and 20 percent of all cases of asthma in industrialized nations.