Dr.Sadeghniiat Assistant Professor of Tehran University of Medical Sciences

1. OCCUPATIONAL ASTHMA Dr.Sadeghniiat Assistant Professor of Tehran University of Medical Sciences Member of Iranian Occupational Medicine Association Member of ATS & ACOEM

2. Work-Related Asthma (WRA):How big is the problem? • An estimated 15% of adult asthma is attributable to occupational factors ATS, 2003

3. WHAT IS OCCUPATIONAL ASTHMA?

4. Variable air flow obstruction & Or • Airway hyperresponviness due to courses and condition : • Working Env ,not outside the workplace • One of the most common occupational respiratory diseases

5. Work-Related Asthma includes: • ‘New-onset asthma’ from sensitizers and irritants • ‘Work-aggravated asthma’ :pre-existent asthma made worse by workplace exposures (Wagner & Wegman, 1998)

6. Types of Occupational Asthma • New Onset - Sensitizer-induced - Irritant induced • Aggravation of underlying asthma • WORK-RELATED ASTHMA = OA + AA

7. Sensitizer-Induced Asthma • More than 300 known etiologic agents • Sensitization to a specific antigen • low molecular-weight, “hapten” DI,WRC • high molecular weight • IgE mediated • Non-IgE mediated (DI,WRC?)

8. Sensitizer-Induced Asthma • Sensitization may occur at <TLV • Sensitizers may also be irritants (e.g. TDI,TMA) • Prior history of atopy does not predict risk of asthma!

9. Low MW Isocyanates Anhydrides Metal salts Epoxy resins Fluxes Persulfate Aldehydes Plicatic acid(WRC) High MW Animal proteins Latex Cereals Seafood Proteolytic enzymes Wood constituents Common Sensitizers(Incomplete List!)

10. Reactive airways dysfunction syndrome (RADS) • Single • High level irritants • Gases • Fume • Smoke

11. Aggravational Asthma • Very common • Initial condition not occupational • irritant exposure

12. Occupational Asthma: Contributing Factors Exposure Factors Host Factors Occupational Asthma Climate/ Geography Factors Industry Factors Adapted from Brooks, 1992

13. risk exposure Dose response relationship KOH 2006

14. Investigation of a case of suspected Occupational Asthma History • Symptoms • Duration • Work history • Is patient zof exposure to any respiratory sensitisers at work? • Timing of symptoms (immediate /delayed) • Improvement away from work

15. Patterns of Association between Asthma Symptoms and Work • Asthma symptoms develop or worsen with a new job or introduction of new materials. • Asthma symptoms develop within minutes of specific activities or exposures at work. • Symptoms improve away from work or on vacation. • Symptoms worsen on return to work after being away.

16. Obstructive pattern • On spirometry • Bronchodilatadors • Provocation tests • Minimum Three – fold • History • Exam • Lung Functions • Skin tests • Therapeutic trial

17. Investigation of a case of suspected Occupational Asthma Clinical investigations • PEFR • Bronchial challenge • Spirometry • Skin prick test • RAST / ELISA

19. HOME-------------WORK-----HOME—WORK--HOMEWORK Rx

20. Confirming the diagnosis of occupational asthma • Specific challenge tests = international golden standard for diagnosis of occupational asthma • to prove the cause-effect relationship between the agent from the workplace and the asthmatic reaction in individual level

21. Occupational asthma, diagnostics • Work related asthmatic symptoms • Exposure to a sensitizing agent at work • Cause-effect relationship between the exposure material and asthma • Sensitization (skin prick tests/specific IgE antibodies) • Positive provocation test • Typical long-term PEF surveillance

22. Diagnostics of occupational asthma • PEF-surveillance at home and at the workplace always, if possible • Positive finding supports the diagnosis • Negative finding does not exclude the diagnosis

23. Prerequirements for challenge tests 1. Clinical picture fits with occupational asthma, but the diagnosis has not yet been verified 2. Asthma is stable. Inhaled steroid may be used, stable dose every evening. 3. Differential diagnostics done. 4. No contraindications to challenge tests.

24. Contraindications to challenge tests • Acute infections • Unstable asthma or some other disease • Poor lung function • Facts, that prevent proper interpretation of the challenge tests (e.g. non co-operating patient) • Anaphylactic or otherwise very strong reaction to the challenge material in history

25. Requirements, when performing challenge tests • 24-hour follow up and facilities to treat acute and late asthmatic ( and other) reactions • Aduquate challenge chamber and well trained staff

26. Criteria for a positive provocation test reaction • minimum 20% FEV1/PEF decrease compared to baseline before exposure and to control test • tests with allergen extracts • minimum 15% decrease in immediate reaction (during one hour after challenge)

27. WRA Surveillance Case Classification

28. therapy • Same as other asthma • Most important=avoidance of exposure

29. Management • Drug treatment • as for non-occupational asthma • Non-drug treatment • Remove from exposure • Review work place • Is prevention possible? • Are control measures adequate? • Health surveillance

30. CAN YOU PREVENT OCCUPATIONAL ASTHMA? • To reduce the likelihood of damaging your lungs you can do the following: • Avoid long exposure • Follow safety rules • Practice good personal habits ie washing up • Keep your workplace clean • Ensure good ventilation • Use respiratory protection - e.g. masks • Don't smoke • Report symptoms and signs of danger

31. What preventative measures can be taken in the workplace? • Substitution of a sensitizing agent in the workplace is a measure that should always be considered, although it is often not possible. • Engineering and ventilation control measures are the next option, but depending on the work process these measures cannot always eliminate the hazard.

32. Treatment and follow up of occupational asthma • Usually regular asthma medication needed • In the follow up the need of asthma medication depends on the disease severity, which varies substantially individually • After discontinuing exposure • Some patients recover totally • In some patients mild asthma symptoms continue to exist • In some patients asthma gets worse • Follow up by both occupational health care and pulmonologist needed

33. the Sentinel Event Notification Systems for Occupational Risks (SENSOR) Program? • Focus on prevention-oriented workplace intervention • Sentinel Health Event • An occupational sentinel health event indicates co-workers may be at risk (Baker, 1989

37. Immunologic IgE mediated High molecular wght Low molecular haptens ? Cell mediated Low molecular Nonimmunologic Irritant-toxic Grain, crab, castor beans Woods, gum acacia Animal dander, urine Epoxy resins Chloramine T Platinum salts di-isocyanates Red Cedar Cobalt Ammonia, chlorine Etiology Mechanism Inducers

38. Methacholine Challenge • + Test confirms airways reactivity only • A functional test not specific for asthma - atopy - transient reactivity • Bronchoprovocation with with specific antigen preferable to diagnose sensitizer-induced asthma • -Tests can occur with quiescent occ asthma

39. Ancillary Tests • Clinical immunology - skin prick tests - RAST - ELISA • PEF or FEV1, symptom and medication diary • Pre/post shift and/or holiday PFTs • Work place HHE

40. Related Diseases • Industrial bronchitis • Airway irritation without asthma • Hypersensitivity pneumonitis • Bronchiolitis obliterans • Metal or polymer fume fever

41. Characteristics of Work Related Asthma • Improvement away from work early in course • Recurrence of symptoms on re-exposure • Delayed asthmatic responses

42. Other Occupational Lung Diseases

43. Related Diseases • Industrial bronchitis • Airway irritation without asthma • Hypersensitivity pneumonitis • Bronchiolitis obliterans • Metal or polymer fume fever

44. Prevention of occupational asthma • Is dependent on co-operation between workplace and occupational health care • Actual knowledge of the sensitizing agents used in the workplace • Work hygienic tasks to minimize exposure and exposure assessments, when needed • Guidance of the right kind of working methods • In occasional exposures possibility to use respiratory protective device • Occupational health care services: check out of workers, when symptoms exist and follow up of lung function measurements

45. Procedures after diagnosing occupational asthmaHow to discontinue/minimize exposure? • Changing agents used in the workplace • Changing work tasks/working area/environment (replacement in another kind of work task or working environment) • Changing the work tasks • Restrictions to the worker • Use of respiratory protective device • Re-education to another occupation ( in Finland legally set that the insurance company of the employer is responsible for re-education) • Retirement

47. Performing challenge tests 1. Confirm, that the asthma is stable • symptoms, FEV1/PEF 24-hour follow-up, spirometry (histamine/metacholine challenge) 2. Challenge with control material • To confirm, that asthma does not react to nonspecific agents • Challenge material and method individually chosen, in order to mimic the challenge method and material of the active agent challenge • Control challenge must be negative • Challenge with active agent is compared with the control challenge 3. Challenge with active agent

48. Challenge test with active agent • Commercial allergen extracts • Tests simulating work tasks (patient handles the material from workplace) • Individual planning: challenge materia, concentration, duration of test e.g. • Occupational hygienist/chemist consultations when needed • Controlled concentrations

49. Challenge chamber • Adequate ventilation • Safety of the patient • Safety of the personnel • exhaust ventilation • easy to clean • Facilities for generation of dusts, vapors and aerosols in controlled concentrations

50. Criteria for a positive provocation test reaction • Findings supporting positive challenge test: • symptoms • wheezing rales • dose-response • increase in hyperreactivity • recovery of the reaction on the following day • increase in exhaled nitric oxide? • increase in peripheral resistance (impulse oscillometry)