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

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

WHAT IS OCCUPATIONAL ASTHMA?

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)

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

 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?) 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!

Common Sensitizers (Incomplete List!) 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

Reactive airways dysfunction syndrome (RADS) Single High level irritants – Gases – Fume – Smoke

Aggravational Asthma Very common Initial condition not occupational irritant exposure

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

KOH 2006 exposure risk Dose response relationship

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.

l History l Exam l Lung Functions l Skin tests n Therapeutic trial l Obstructive pattern u On spirometry l Bronchodilatadors l Provocation tests l Minimum Three – fold

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

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% FEV 1 /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 Case of WRA New-Onset Asthma (NOA) Occupational Asthma (OA) Known Asthma Inducer With or without Objective Evidence Unknown Asthma Inducer With or without Objective Evidence Reactive Airways Dysfunction Syndrome (RADS) Work-Aggravated Asthma (WAA)

therapy Same as other asthma Most important=avoidance of exposure

Management 1.Drug treatment as for non-occupational asthma 2.Non-drug treatment Remove from exposure Review work place – Is prevention possible? – Are control measures adequate? 3.Health surveillance

2/9930 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

2/9931 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

Etiology Mechanism Inducers 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

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

Ancillary Tests Clinical immunology - skin prick tests - RAST - ELISA PEF or FEV 1, 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 asthma How 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)