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R pr d fr AustRAliAn FAmily PhysiciAn Vol. 39, no. 1/2, JAnuARy/FebRuARy 20 39

A ra a w rkp a . 13 W rk xa r a da a w r r f a a, wd v p d f r r d a d r g w rk f , adv r aff d w rkp a fa r

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sensitiser induced OA (with latency), and irritant induced OA (without latency).

Sensitiser induced OA ov r 90% f oA r d d oA. 5 t f r f a a d d v pf a fr r g ar xp r ap f a a w rkp a , a ainhaled protein (eg. bakers flour) or chemical(eg. isocyanates a group of chemicals with

Work related asthmaDiagnosis and management

Background Work related asthma (WRA) is a common condition and is under recognised in Australia. Work related asthma refers to the development of new asthma due to occupational factors (occupational asthma) and the worsening of asthma control due to occupational factors (work exacerbated asthma).

ObjectiveThis article discusses the diagnosis and management of work related asthma in Australia.

Discussion All clinicians who treat adult patients with asthma should enquire about the patientsoccupation. Key features of WRA include: a temporal association between asthmasymptoms and work activities (especially an improvement in symptoms when away fromthe workplace), identification of relevant workplace exposures (eg. use of a known causeof occupational asthma) and the development of respiratory symptoms in coworkers.Optimal management of WRA requires early recognition and accurate diagnosis.Increased awareness of WRA and the introduction of effective workplace control shouldreduce the prevalence of WRA and the overall burden of asthma in our community.

Keywords: asthma; occupational diseases

Ryan F HoyMichael J AbramsonMalcolm R Sim

Case study Farid, 18 years of age, has a past history of seasonal hay fever. He presents with almostdaily symptoms of itchy eyes, stuffy nose,cough, shortness of breath and wheeze. Hesays he wakes most days with a wheeze anddescribes frequent use of salbutamol. Hehas recently been on holiday and felt betterduring that time.On further questioning, Farid reveals thathe has been working in a bakery for 12months. One of his roles is to weigh theflour. His nasal and eye symptoms started 3months ago, followed by the chest symptoms2 months later. His symptoms improvemodestly over the weekend and recur withinminutes of starting work.

Asthma has a high prevalence in theAustralian community and certainoccupations have the potential toinfluence the onset and severity of asthmasymptoms. Occupational factors needto be carefully considered as part of thediagnosis and management of all workingage adults with asthma. The Case study is a typical scenario of work related

asthma (WRA).

W rk r a d a a r f r a aw r a a f d w rk a dencompasses both occupational asthma (OA)and work exacerbated asthma (WEA)1 (Figure 1).o pa a a a r f r d v p fnew onset asthma (or the recurrence of previouslyquiescent asthma) due to exposure to one of af w dr d a w a f d


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w rk r a r k f xp r a d d v p f pr v a pa a d a . 1

Diagnosis of WRA ev pra r w a a xp r a a ar a f d d ag f WRA

d ff . t f r p f r prof asthma (Table 1). Other conditions that maya w rk a a d r p ra r pinclude nonspecific airway irritation (such as thatassociated with solvent exposure), upper airwayd f , a d p r v p .

History

t r ar f a r r a d ra suspicion of WRA (Table 2 ). These features vary

w d ff r p f WRA a d a d ff d ff r a fr a a a f

w rk a a d r p ra r p .t a ar a f q r d d :

g ra a a p a d r , p raa a w p a d w rk, prf w rk r w ar r p ra r p , a dd a d f r a a xp r r .

t A r a c g f c P ar d k q a k d f

d ra f 195 325 a f a a/ w rk r / ar d w rkp a xp r . 13

b ra , V r a a d ta a a

s rv a f A ra a w rkp a ba dRespiratory Events (SABRE) program, the incidenceof asthma was only 30.9 (95% confidence interval26.835.5) cases/million workers/year.2 s ar ,a a p a a r p r a 70 p a d a f a a p r ar(accepted claims that result in death, permanentd a r p rar d a v v g 5 rmore days off work).13 s rv a a d w rk r

p a da a a a ; WRA k a gr a r pr A ra a a rr gg d p d g a d . 13

Barriers to the diagnosis of WRA

A a f p r v a rf w rp r , r f r a r p r a a

p r g ra pra r f rf r r va a . 14,15 la k f q r aw rk r a d f r p ra r p GP a a d f d a a r a f rd a d ag f WRA. 16 o r arr rinclude workers compensation system issuesa d pa f ar f j a d r d

. 16 u f r a , f ar ar w f da , a d ag f oA a ad d ra d . 17

Fa r rr d f oA ad g gp r a a r , d f r g r d fa a d a , a d a a a , prr v r , d g f a d a a dd a . 18 A g , d a froA av r p r d. 19 i add , fa r d f d v d a a f oA a av r

a w d ra g f d g a a ard gagent in some spray paints).1 t f r f oA ara r d a p r d f a w f r

xp r a a d d v p fa a p . t p r d a var fr a f ww k v ra ar . o d d ra d40% f a d v p d w 2 ar f axp r , 20% af r 10 ar . 6 A r fa p a r k fa r f r r d d oA dto certain agents (eg. animal and flour antigens).7

Irritant induced OA irr a d d oA d v p f w g ainflammatory (nonimmunological) response of

w r r p ra r ra a rr a xp rr d a w rkp a . 8,9 t w rk r w

ara r a d v p r p ra r pwithin minutes to hours of the exposure (withoutlatency). Reactive airways dysfunction syndrome(RADS) is the clearest example of irritant inducedoA a d d v p f w g a g a vxp r , a a p . 10 R rr w rv f rr a xp r a a ad

d v p f rr a d d oA. 8

Epidemiology

A r a p p a rv d d n w s Wa a d a pa axp r a f r 9.5% f ad a a a r g . 11 h w v r, r a a da a a

r p r d a a a 15% f ad a a k d pa a xp r . 12 ba d a

p p a a r a r k f 915% a d 20 570w a f a a rr g w rk g ag d

A ra a a ar, A ra a iof Health and Welfare (AIHW) expect an annual

Table 1. National Asthma Council of Australia recommendations for thediagnosis of asthma 21

There is no gold standard for thediagnosis of asthma Diagnosis is based on history, physicalexamination and supportive diagnostictesting, including spirometry A diagnosis of asthma can be madewith confidence in an adult whenthe person has variable symptoms(especially cough, chest tightness,wheeze and shortness of breath)and spirometry shows significantlyreversible airflow limitation (FEV 1 at

least 12% and 200 mL higher thanbaseline) Challenge tests (eg. methacholinechallenge) may help confirm adiagnosis of asthma. These should beperformed only in specialist facilities

Consider referral to a specialist respiratory physician when thediagnosis is uncertain and for patientsin whom occupational asthma issuspected

Figure 1. Relationship of asthma to the workplace 2 (these groups are not mutually exclusive)

Work relatedasthma

Occupational asthma

caused by work

Sensitiserinduced OA

Work exacerbated

asthma

Irritant induced OA


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clinicalWork related asthma diagnosis and management

R pr d fr AustRAliAn FAmily PhysiciAn Vol. 39, no. 1/2, JAnuARy/FebRuARy 20 41

physician, occupational physician and/or allergisw xp r f d. W a k w dga a ar a f A ra a pr v

ar r q r d a w r a

p a . t t ra s f A ra aand New Zealand (TSANZ) and the AustralasianFa f o pa a a d e v r aMedicine (AFOEM) can provide assistance inlocating specialists (see Resources ).

Management G ra a a a ag f pa wWRA, d g f a a d a ,

d ad r pra a a g d(see Resources ).1,5,21 b d a dard a aa ag , pa w WRA a r q radv r gard g ff f w rkp a xp r r a a r .

u a a v r , pa w WeAa d rr a d d oA a a r a

r j f a r ar ak xp r w rkp a r gg r a d r p ra r rr a . 1

m a r a d f r a rpr d , a g v a r w rk pr ,or using an appropriate face mask (respirator) fo

r r xp r . 3,8

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t d a w w rk r r a / rp a d a azard f r aff r w rk r . u f r a r v g

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Identification of a sensitisingagent or irritant c rr r ar v r 400 k w gag . t a f d a w d ra g f j

and industries (Table 3 ) and the list is continuallyxpa d g. l f d f d ag ar ava aonline (seeResources ). Material safety data sheets(MSDS) are forms containing information about

a d pr p r f ad a w rkp a . t f r ar va ar f f r a r gard g x a d k wa ff f pr d a d d pr v d d w rk r r p r r q . la k fd f a f a g ag r g r kjob (eg. baker) does not exclude the diagnosis ofoA. A d p pa a r , d

p f a a dard a , f r q r d d f r p ag . A w rkp a va ar a r a f r a p d a , rv w arg d, a d ad q a f r a r .t w d a p d f r f rr a

d d oA f w a g g v xp revent (RADS), which usually enables accurated f a f rr a . h w v r, pw r v rr a xp r a a a

a a. 8,9 t r a a r v r a ar a;

p d aff d w rk r d r f rr d f rf r r p a va a .

Investigations and referralt a ra d ag f WRA r q r a p x

a f v ga , d g r apr v a g, w ar p rf r dw pa w rk g. 1 W r da a a pa p d f av g

WRA are referred to a specialist (eg. respiratory

a pa w a a ar g r w r gd r g r w rk g f 1,20: were there changes in work processes in the

p r d pr d g f p ? t

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was there an unusual work exposure within24 r f r f a a a

p ? t a k f a r f rr ad d oA. s p w f v rg r q r rg d a r a

a d r xp d w rk r a aff d do asthma symptoms differ during times away

fr w rk a w k d r dar r x d d awa fr w rk?id f a f a p ra a a

w w rk a v a d a a p a g d ark r f WRA. i r f q r a a pr v a ap w awa fr w rkp a ,

p a f r a x d d p r d a ada , ra r a a r rr w r r

w rk. t r rr f a a p wd p d xp r p f gag . h w v r, a p ra a a w

d r a w r oA a dWeA, a d a ga v r p d

x d r oA. t a a a w v r a d g a d g oA 1

are there symptoms of rhinitis and/orj v p a ar w r w

w rk? e p a w r d d oAdue to agents such as bakers flour and animalda d r, w rk r w f d v p pof rhinitis (eg. sneezing, nasal congestion)a w rkp a f r r rr wa a p .

Table 2. Features of various forms of work related asthma 5

Work exacerbatedasthma

Sensitiser induced occupationalasthma

Irritant induced occupationalasthma

Symptoms of asthma Yes Yes Yes

Onset Before or during working life Onset or recurrence during workinglife. Usually first develops some

weeks to months after first exposure

Usually within 24 hours of exposure tolarge quantity of respiratory irritant

Relation to workschedule

Worse on one or more dayswhile at work

Symptoms worse during or after awork shift and improve when awayfrom work

Often none

Other Exposure at work to asthmaexacerbating factors such asdust, smoke, fumes, cold

Exposure to a known sensitiser Persistence of symptoms for at least 12weeks, but no previously documentedasthma or chronic lung disease


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42 R pr d fr AustRAliAn FAmily PhysiciAn Vol. 39, no. 1/2, JAnuARy/FebRuARy 2010

f ep d g a d Pr v v m d , Faf m d , n r g a d h a s ,m a u v r , m r , V r a.

c f f r : d ar d.

References1. Tarlo SM, Balmes J, Balkissoon R, et al. Diagnosis

a d a ag f w rk-r a d a a. c2008;134;141s.

2. Elder D, Abramson M, FishD, Johnson A, McKenzieD, Sim M. Surveillance of Australian workplaceBased Respiratory Events (SABRE): notifications for

f r 3.5 ar a d va da f pa aasthma cases. Occup Med (Lond) 2004;54:3959.

3. Bernstein IL, Chan-Yeung M, Malo JL, BernsteinDI,d r . A a w rkp a . 3rd d . n w y rk:ta r & Fra , 2006.

4. Henneberger PK. Work-exacerbated asthma. Currop A rg c i 2007;7:14651.

5. tar sm, l Gm. o pa a a a: aappr a d ag a d a ag . ca m dA J 2003;168:86771.

6. Malo JL, Ghezzo H, DAquino C, LArcheveque J,car r A, c a -y g m. na ra r f -pa a a a: r va f p f ag a d

r fa r ra f d v p f p- aff d j . J A rg c i1992;90:93744.

7. n v Rm, P k r g cA. i a p a d k g p r-a w rkp a ? o p m d 1999;49:197200.

8. mapp ce, b P, ma r P, Fa r lm. s af ar : pa a a a. A J R p r crcar m d 2005;172:280305.

9. tar sm. W rkp a r p ra r rr a a da a. o p m d 2000;15:47184.

10. br k sm, W mA, b r il. R a vairways dysfunction syndrome (RADS) Persistenta a dr af r g v rr a xp r .c 1985;88:37684.

11. Johnson A, Toelle BG, Yates D, et al. Occupationalasthma in New South Wales (NSW): a populationa d d . o p m d 2006;56:25862.

12. Torn K,Blanc PD. Asthma caused byoccupationalxp r a a a a f -a f p p a -a r a fra . bmcP m d 2009;9:7.

13. A ra a i f h a a d W far .o pa a a a A ra a. b . 59. ca. Aus 101. ca rra: AihW, 2008.

14. R f d AR, Pa mc. P r p f a a. la1976;1:8824.

15. b lP, l a P, t r h. P r p r gf d d r r a a d x f awar -

f a a p . c 1994;105;14303.16. Poonai N, vanDiepenS, Bharatha A, et al. Barriers to

d ag f pa a a a o ar . ca JP h a 2005;96:2303.

17. Vandenplas O, Toren K, Blanc PD. Health and socio- pa f w rk-r a d a a. e r R p r

J 2003;22:68997.18. A W, m r Vc, b rg Ps. FeV1 d -pa a a a. t rax 2006;61:7515.

19. Ortega HG, Kreiss K, Schill DP, et al. Fatal asthmafr p wd r g ark ar ag a d r v w f fa a

pa a a a ra r . A J i d m d2002;42:504.

20. Dykewicz MS. Occupationalasthma: current con-p pa g , d ag , a d a ag .

J A rg c i 2009;123:51928.21. A a ma ag ha d k 2006. s

m r : na a A a c A ra a l d,2006.

The diagnosis of WRA can be difficult and mayr q r r f rra a p a .

Resources Lists of identified sensitising agents: www.

r p.fr/a a /a apr /ag . a dwww. .g v. k/a a/a ag .pdf

t t ra s f A ra a a d n wZealand (TSANZ):www. ra . rg.a /

The Australasian Faculty of Occupational andEnvironmental Medicine (AFOEM):p://af .ra p. d .a /

National Asthma Council of Australia guide-: www. a a a a. rg.a / //v w/29/32/.

AuthorsR a F h mbbs, moeh, FRAcP, a r p ra rphysician, Department of Allergy, Immunologya d R p ra r m d , t A fr d h p a ,and Research Fellow, Department of Epidemiology

a d Pr v v m d , Fa f m d ,n r g a d h a s , m a u v r ,m r , V r a. r. @a fr d. rg.a

Michael J Abramson MBBS, BMedSc, PhD,FRACP, FAFPHM, is Professor, Department ofep d g a d Pr v v m d , Fa fm d , n r g a d h a s , m au v r , m r , V r a

Malcolm R Sim MBBS, MSc, PhD, FAFOEM,FAFPHM, is Director, Monash Centre forOccupational & Environmental Health, Department

r q r d, a g g xp r r,v a w v , k av a ga vpa a a r a d g r r p ra r

f . t d adv pa av r w rkp a d ff a d r q r

a a p a f d.A a p f a ag

f a f r f WRA ff v aw : r a g p a , pa , p r, w rkp a pa a a a d af

system, and workers compensation organisations.

Summary of important points Work related asthma is a common condition,

w d r r g d a d d rd ag d A ra a.

An occupational history should be a standardp f pr ar a ar .

Patients with respiratory symptoms should bep f a q d a r a pf p w rk, par ar f a g r kpr f r xp r d f d.

It is essential that all clinicians who treatad w a a q r a rpatients occupation.

The first step in diagnosing WRA is to confirm pr f a a, w d d r ak w pa w rk g.

Table 3. Common sensitising agents and occupations where workers may beexposed 2,3

Agent Example occupations

Low molecular weight agents

Wood dust (eg. western redcedar, redwood, oak)

Carpenters, builders, sawmill workers, sanders, modelbuilders

Isocyanates Automotive industry, mechanics, painters, adhesiveworkers, chemical industry, polyurethane foam workers

Formaldehyde Cosmetics industry, embalmers, foundry workers,hairdressers, laboratory staff, medical personnel, paperindustry, plastics industry, rubber industry, tanners

Platinum salts Chemists, dentists, electronics industry,photographers, metallurgists

High molecular weight agents

Latex Health care workers, textile industry, toymanufacturers

Flour and grain dust Bakers, cooks, pizza makers, grocers, farmers, combine

harvester driversAnimal allergens (eg. urine,dander)

Veterinary surgery workers, animal care workers,laboratory workers, jockeys, animal breeders, pet shopemployees

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