Allergic Occupational Asthma

1. Pathophysiology
   1. Sensitization to specific workplace chemical
   2. Initial response delayed from weeks to years
2. Causes: High Molecular Weight Substance Exposure (>1 kilodalton)
   1. Background
      1. Type I Hypersensitivity Reaction (IgE mediated)
      2. Symptoms within 20 minutes of exposure
      3. Resolves gradually within 1 to 2 hours
   2. Causes
      1. Flours or grain dust (Bakers, farmers, grain process)
      2. Insects (silk-processing, research)
      3. Seafood or marine organisms (seafood processors)
      4. Animal dander (animal handlers)
      5. Enzymes (Detergents, food industry, blood process)
      6. Gums or latex (manufacturing, health care)
3. Causes: Low Molecular Weight Substance Exposure (<1 kilodalton)
   1. Background
      1. Allergic response of unclear mechanism
      2. Symptoms occur 3-4 hours after exposure
      3. Results in severe airway inflammation
   2. Causes
      1. Colophony: Abietic acid (electronic industry)
      2. Plicatic acid: Western red cedar dust (woodwork)
      3. Metals: Chromium, Platinum, Nickel (Refinery)
      4. Dyes (Textile industry)
      5. Persulfate salts, a bleaching agent (Hair dressing)
      6. Anhydrides: Trimellitic, Phthalic (Plastics)
      7. Acrylates such as Methacrylate (Adhesive workers)
      8. Glutaraldehyde or Formaldehyde (Health care)
      9. Pharmaceuticals (Pharmaceutical Industry)
      10. Polyurethane (paints and adhesives)
      11. Diisocyanate: Toluene, Diphenylmethane, Hexamethylene
          1. Used in plastic and Rubber
          2. Used to create foam insulation
          3. Used to harden polyurethan paints (auto, boat)
4. Differential Diagnosis
   1. Intrinsic Asthma
      1. Nonspecific triggers for airway hyperresponsiveness
   2. Reactive Airway Dysfunction Syndrome
      1. Follows very high irritant exposure
5. References
   1. Bebko (2016) Am Fam Physician 93(12): 1000-6 [PubMed]
   2. Chan-Yeung (1995) Chest 108:1084-117 [PubMed]
   3. Friedman-Jimenez (2000) Am J Ind Med 37:121-41 [PubMed]
   4. Youakim (2001) Am Fam Physician 64(11):1839-48 [PubMed]