Table 1

Frequently reported causes of occupational asthma, by molecular weight

Agents and sourceWorkers at risk
High molecular weight agentsAnimal urine and proteins (eg, mice, rats, cows, horses, insects).Laboratory work, veterinarians, farmers, animal handlers, greenhouse workers.
Cereal grains and flour (eg, wheat, rye, barley).Bakers, pizza and pastry makers, grain storage handlers, millers.
Enzymes (eg, amylase, protease, lipase).Bakers, pastry makers, food process workers (amylase), cleaners, healthcare workers, detergent manufacturers.
Natural rubber latex.Healthcare workers, rubber glove makers.
Other animal or plant-derived products: milk and egg protein, beans (eg, green coffee, castor, soy), spices, gums (eg, acacia, guar).Food producers and processors, bakers, cooks. Pharmaceutical industry, printing, carpet making (gums).
Seafood proteins (eg, fish, crustaceans, molluscs).Fish and seafood processing.
Low molecular weight agentsAcid anhydrides (eg, tri-mellitic anhydride, phthalic anhydride).Makers and processors of epoxy resins (adhesives, surface coatings).
Acrylic monomers (eg, cyanoacrylate, methyl methacrylate).Adhesive work, dental professionals, aestheticians, printing.
Biocides (eg, aldehydes, chlorine releasing agents, quaternary ammonium compound).Healthcare workers, cleaners, swimming pool attendants.
Colophony (rosin) in solder flux (abietic acid).Electronic soldering, work with adhesives and surface coatings.
Di-isocyanates (eg, toluene di-isocyanate, methylene diphenyl di-isocyanate, hexa-methylene di-isocyanate).Spray painters, foundry workers, makers and processors of polyurethane substances (eg, adhesives, foams, hard surface coatings).
Drugs (eg, opiates, penicillins, other antibiotics).Pharmaceutical manufacture, healthcare workers with repeated exposures.
Metals (eg, chromium, cobalt, nickel, zinc) and metalworking fluids.Welders, metal platers, hard metal manufacturing.
CNC grinders and lathe operators.
Persulphates and henna.Hairdressers.
Platinum and other precious metal salts.Refinery workers.
Some wood dust (eg, iroko, obeche, sapele, western red cedar) and MDF (medium-density fibreboard)Carpenters, joiners, millers, forestry workers.
  • CNC, computerised numerical control; MDF, medium density fibreboard.