Diagnostics of occupational asthma

(history, exposure, allergologigal investigations, differential diagnostics)

H. Keskinen MD

Finnish Institute of Occupational Health

Occupational asthma, diagnostics

work-related asthmatic symptoms

exposure to a sensitizing agent at work

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 related to work

– during working hours– in the evening after the work day– during the night after work days

no symptoms during days off later symptoms also during weekends,

but improving when away from work for longer periods

Causes of cough/dyspnea

bronchial asthma respiratory infections COPD hyperventilation medication reflux disease cardiac causes malignant disorders

Occupational asthma/ history

What is your work? (ask every patient with cough/dyspnea!)

What are the symptoms? When did they begin? How are they related to work? Specific agents ? old? new? Change in working habits? Change in the work environment? Symptoms of respiratory infection? Smoking?

Occupational asthma, exposure

exposure in own work exposure as bystander

– other work procedures in the same hall– from the neighbouring hall

non-occupational sensitizing agents – pets– hobbies

Exposure, sources of data

patient occupational health services employer safety data sheets importer/manufacturer registers of occupational

diseases literature

Bakery work, sensitizers

flours enzymes storage mites spices egg milk powder sesame seed

Cattle breeding, sensitizers

animal epithelia feed grains (rye, barley,

wheat) storage mites natural rubber feed additives? (fish

powder, enzymes, soya)

diisocyanates (TDI, MDI, HDI) epoxy resins, organic acid anhydride or amine hardeners phthalates formaldehyde azodicarbonamide cyanoacrylates methacrylates polyfunctional aziridine hardener

Manufacturing/use of plastic products, sensitizers

Health services, sensitizers clinics

– natural rubber– chloramine T– glutaraldehyde– formaldehyde– animal epithelia (veterinary

work)

dental care– natural rubber– methacrylates– chloramine T– formaldehyde– ammonium persulphate

Hair dressers, sensitizers

Persulphates Permanent wave chemicals Hair sprays Dyes Natural rubber

Electronics, sensitizers

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

Painting, sensitizers

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

Wood works, sensitizers

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

Metal work, sensitizers

Welding fumes (MMA) and grinding dusts of stainless steel

Hard metal dust Welding fumes of painted steel (2-component

paints) Aerosols of cutting fluids Other welding fumes?

Basic investigations

physical status, lung auscultation chest X-ray (also nasal sinuses if needed) blood sedimentation rate, CRP, blood count,

eosinophils spirometry, also after bronchodilating medicine histamine/metacholine challenge exercise test (EKG, FEV1, blood gases), if needed diffusion capacity, if needed total IgE skin prick tests (common environmental allergens)

Investigations of allergy/environmental allergens

Skin prick tests (SPT) – common environmental allergenes

(pollen of trees/grasses, animal epithelia, house dust mites, moulds, natural rubber)

– commercial extracts (ALK Abello, Denmark)

Total IgE 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

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 allergenschemicals, conjugated with HSA

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

Note: – extracts of work-related sensitizers not

standardized, wrong negative/positive tests?!– only IgE-mediated allergies are found

Chemicals and specific IgE

Asthma due to diisocyanates - only about 20% of the diagnosed cases have been IgE-mediated (RAST +:ve)

Asthma due to organic acid anhydrides - most often RAST +:ve

Occupational asthma due to formaldedyde - rarely RAST +:ve

Negative RAST does not exclude occupational asthma!

Occupational asthma, differential diagnostics

Non-occupational allergies– e.g. pollen, pets – constant asthma symptoms, irritants at work cause

increasing symptoms

Intrinsic-type asthma– all irritants and strain, also at work, increase symptoms

COPD– marked obstruction, strain and irritants increase symptoms

Occupational asthma, diagnostics

history– work-related asthmatic symptoms– exposure to a sensitizing agent at

work

clinical investigations for verifying the cause-effect– sensitization to agents at work– cause-effect relationship between the

exposure and astma of the patient