Diagnostics of occupational asthma (history, exposure, allergologigal investigations, differential diagnostics) H. Keskinen MD Finnish Institute of Occupational Health

Occupational asthma, diagnostics l work-related asthmatic symptoms l exposure to a sensitizing agent at work l cause-effect relationship between the exposure and asthma – sensitization (skin prick tests / specific IgE antibodies) – typical long-term PEF surveillance – positive provocation tests

Occupational asthma, symptoms Cough, production of mucus, dyspnea l related to work – during working hours – in the evening after the work day – during the night after work days l no symptoms during days off l later symptoms also during weekends, but improving when away from work for longer periods

Causes of cough/dyspnea l bronchial asthma l respiratory infections l COPD l hyperventilation l medication l reflux disease l cardiac causes l malignant disorders

Occupational asthma/ history l What is your work? (ask every patient with cough/dyspnea!) l What are the symptoms? l When did they begin? l How are they related to work? l Specific agents ? old? new? l Change in working habits? l Change in the work environment? l Symptoms of respiratory infection? l Smoking?

Occupational asthma, exposure l exposure in own work l exposure as bystander – other work procedures in the same hall – from the neighbouring hall l non-occupational sensitizing agents – pets – hobbies

Exposure, sources of data l patient l occupational health services l employer l safety data sheets l importer/manufacturer l registers of occupational diseases l literature

Bakery work, sensitizers l flours l enzymes l storage mites l spices l egg l milk powder l sesame seed

Cattle breeding, sensitizers l animal epithelia l feed grains (rye, barley, wheat) l storage mites l natural rubber l feed additives? (fish powder, enzymes, soya)

l diisocyanates (TDI, MDI, HDI) l epoxy resins, organic acid anhydride or amine hardeners l phthalates l formaldehyde l azodicarbonamide l cyanoacrylates l methacrylates l polyfunctional aziridine hardener Manufacturing/use of plastic products, sensitizers

Health services, sensitizers l clinics – natural rubber – chloramine T – glutaraldehyde – formaldehyde – animal epithelia (veterinary work) l dental care – natural rubber – methacrylates – chloramine T – formaldehyde – ammonium persulphate

Hair dressers, sensitizers l Persulphates l Permanent wave chemicals l Hair sprays l Dyes l Natural rubber

Electronics, sensitizers l Soft soldering fumes (colophony) l Diisocyanate cured varnishes l Formaldehyde l Epoxy resins, organic acid anhydrides l Acrylate glues

Painting, sensitizers l Formaldehyde l Diisocyanate cured paints l Epoxypaints, amine hardeners l Epoxy powder paints l Polyester powder paints l Paints with azidirine hardeners

Wood works, sensitizers l Formaldehyde (glues and shellacks) l Wood dusts (exotic woods!) l Diisocyanate hardened paints l Aziridine hardened paints l Moulds (mouldy wood dusts)

Metal work, sensitizers l Welding fumes (MMA) and grinding dusts of stainless steel l Hard metal dust l Welding fumes of painted steel (2-component paints) l Aerosols of cutting fluids l Other welding fumes?

Basic investigations l physical status, lung auscultation l chest X-ray (also nasal sinuses if needed) l blood sedimentation rate, CRP, blood count, eosinophils l spirometry, also after bronchodilating medicine l histamine/metacholine challenge l exercise test (EKG, FEV1, blood gases), if needed l diffusion capacity, if needed l total IgE l skin prick tests (common environmental allergens)

Investigations of allergy/environmental allergens l Skin prick tests (SPT) – common environmental allergenes (pollen of trees/grasses, animal epithelia, house dust mites, moulds, natural rubber) – commercial extracts (ALK Abello, Denmark) l Total IgE l Determination of specific IgE – if skin prick test not possible – specific allergens, not available as SPT – commercial tests (Pharmacia, Sweden)

Skin prick tests, sensitizing agents at work l Skin prick tests – commercial extracts (ALK Abello, Denmark) e.g.: flours, animal epithelia, moulds, storage mites, natural rubber (chemicals not commercially available as SPT!) – "in-house" extracts (quality? testing of control persons!)  freeze-dried allergens  chemicals, conjugated with HSA l Note: - extracts of work-related sensitizers not standardized, wrong negative/positive tests?! - only IgE-mediated allergies are found

Determination of specific IgE, sensitizing agents at work – commercial tests (Pharmacia, Sweden) (flours, animal epithelia, moulds, storage mites, natural rubber, chloramineT, diisocyanates, acid anhydrides, formaldehyde) – "tailor made" tests l Note: – extracts of work-related sensitizers not standardized, wrong negative/positive tests?! – only IgE-mediated allergies are found

Chemicals and specific IgE l Asthma due to diisocyanates - only about 20% of the diagnosed cases have been IgE-mediated (RAST +:ve) l Asthma due to organic acid anhydrides - most often RAST +:ve l Occupational asthma due to formaldedyde - rarely RAST +:ve l Negative RAST does not exclude occupational asthma!

Occupational asthma, differential diagnostics l Non-occupational allergies – e.g. pollen, pets – constant asthma symptoms, irritants at work cause increasing symptoms l Intrinsic-type asthma – all irritants and strain, also at work, increase symptoms l COPD – marked obstruction, strain and irritants increase symptoms

Occupational asthma, diagnostics l history – work-related asthmatic symptoms – exposure to a sensitizing agent at work l clinical investigations for verifying the cause-effect – sensitization to agents at work – cause-effect relationship between the exposure and astma of the patient