Increased risk of asthma among Finnish construction workers

Transcription

1 Occupatioal Medicie 2003;53: DOI: /occmed/kqg112 Icreased risk of asthma amog Fiish costructio workers Riitta Saui, Pau Oksa, Solja Huikko, Pekka Roto ad Jukka Uitti Itroductio Aim Method To determie the risk of asthma amog 7891 Fiish costructio workers i the Pirkamaa Regio of souther Filad. Retrospective cohort study of hospital records of the Tampere Uiversity Hospital. A populatio of Pirkamaa paper mill workers ( = 2686) ad the Pirkamaa workig age populatio ( = ) served as referece populatios. Results There were 147 ew of asthma amog the costructio workers i The aual rate was 37 per workers ad the odds ratio was 2.1 [95% cofidece iterval (CI) = ] for the wome ad 1.8 (95% CI = ) for the me whe compared with the geeral workig age populatio. I geeral, the risk of asthma amog the paper mill workers did ot differ from the risk of asthma amog the geeral workig age populatio. The costructio workers had a icreased risk for asthma, although the umber of reported of occupatioal asthma was lower for the costructio workers tha for the paper mill workers or for the workig populatio. Coclusio Key words Costructio work, especially dusty tasks, was associated with a elevated risk of asthma. Thus the effect of exposure to irritat agets may have a role i the developmet of asthma amog costructio workers. For the most part, these of asthma do ot meet the criteria for occupatioal asthma because the specified causal aget ca ot be defied. The aetiologic agets ad mechaisms of asthma i costructio work should be clarified for prevetive measures. Asthma; costructio worker; occupatioal asthma; occupatioal disease; workrelated asthma. Received 17 December 2002 Revised 27 May 2003 Accepted 7 July 2003 Occupatioal exposure to sesitizig agets such as isocyaates, epoxides, acrylates, cobalt, isothiazolioe, aziridie, wood dust, formaldehyde, chromium, ickel ad rubber chemicals is possible i costructio work [1]. No-specific irritatig agets i the air of the workplace may also play a part i the developmet of asthma [2 5]. The risk of asthma amog costructio workers has Tampere Regioal Istitute of Occupatioal Health ad Cliic of Occupatioal Medicie (Tampere Uiversity Hospital), Tampere, Filad. Correspodece to: Jukka Uitti, Tampere Regioal Istitute of Occupatioal Health, PO Box 486, FIN Tampere, Filad. Tel: ; fax: ; jukka.uitti@ttl.fi geerally ot bee cosidered high, but the healthy worker effect of this mobile workforce may have reduced the reported rate of asthma. I the USA, the rate ratio of self-reported asthma amog costructio workers was foud to be 0.82 [6]. Furthermore, the costructio idustry may have sub-populatios of workers whose elevated risk of asthma remais urecogized i research o the etire set of diverse trades [7]. Studies usig self-reportig, physicia-reportig or isurace-based surveillace have idicated a icreased risk of ashma i some specific occupatioal groups of the costructio idustry [8 10]. I a study from Sigapore, the risk of asthma amog costructio or reovatio workers was icreased [odds ratio (OR) = 2.24, 95% cofidece iterval (CI) = ] [2]. However, the occupatio Occupatioal Medicie, Vol. 53 No. 8 Society of Occupatioal Medicie 2003; all rights reserved 527

2 528 OCCUPATIONAL MEDICINE had bee determied by the phrase ever employed i costructio idustry, which does ot make the observed associatios highly specific. Oly betwee oe ad six of occupatioal asthma ( / workers) were reported to the Fiish Register of Occupatioal Diseases for costructio workers aually betwee 1991 ad 1995, totallig 14 [11]. The problem may be that, geerally, oly about oe-third of the occupatioal diseases of costructio workers are reported [12, 13]. O the other had, workers with severe respiratory problems i dusty tasks probably choose aother career. The aim of this study was to assess the icidece of asthma ad calculate the OR for this disease amog costructio workers i Filad. Methods We gathered all the ew of asthma diagosed by chest physicias of the Tampere Uiversity Hospital i souther Filad betwee 1991 ad 1995 amog people of years of age. I the Pirkamaa regio, this is the oly hospital with a pulmoary cliic, ad >95% of all asthma i the regio are diagosed there. Approximately workig-aged people (20 64 years) live i the catchmet area of the pulmoary cliic. The patiets with a diagosis of extrisic asthma, itrisic asthma, other specified asthma or o-specified asthma were icluded i this study. No-specified asthma comprised most of the suspected asthma uder examiatio. About half of them did ot meet the criteria of asthma i a more detailed study, although the patiets had asthma-like symptoms. Durig , the Tampere Uiversity Hospital used the America Thoracic Society criteria [14] i its diagostic procedure. I this study, we defied a costructio worker as a perso havig worked i the costructio idustry for >3 moths yearly durig at least 3 years betwee 1980 ad If a perso had stopped workig i the costructio idustry i 1988 or earlier, he was excluded from the costructio worker populatio. We liked the register of the Employmet Pesio Fud of costructio workers ad the hospital records of the asthma patiets. The Employmet Pesio Fud icludes all costructio workers except muicipal employees ad idepedet etrepreeurs, who costitute <15% of all costructio workers. Because the occurrece of asthma differs for me ad wome, ad it also differs for various ages, we stratified the data accordig to geder ad age. The yearly umber of costructio workers was obtaied from the records of the pesio fud. The umbers separated by geder, age ad workig moths are available for the whole coutry, but ot separately for the Pirkamaa regio. We estimated the umber of workers i Pirkamaa i 1991 usig the umbers of perso-years for the whole of Filad ad Pirkamaa, both of which were available. The umber of female costructio workers (<6% i the etire Fiish costructio worker populatio) was so low that agestratified data could ot be obtaied accurately eough for them. Therefore, the age-specific ORs have ot bee show for wome. Paper workers from oe paper mill compay i the Pirkamaa regio were selected as cotrols, represetig a idustrial populatio. The umber of workers had remaied costat durig the years of the study ad, because data for earlier years were ot available, we used data for 1994 to determie the size of the paper mill worker cohort. The Statistical Yearbook of Filad ad Cetral Statistical Office of Filad provided iformatio o the umber of people i the geeral workig age populatio i 1991 i Pirkamaa. The age-specific geder distributio of the Pirkamaa regio was ot available, but it was available for the etire coutry. Thus, we used the age-specific geder distributio of Filad ad fitted it ito the agespecific distributio of the ihabitats of the Pirkamaa regio. The costructio ad paper mill workers were excluded from these umbers. We compared the OR of asthma betwee the costructio workers ad both the paper mill workers ad the geeral workig age populatio of the Pirkamaa regio. The ORs ad their CIs were calculated as described by Garder ad Altma [15] with Cofidece Iterval Aalysis (versio 1.1) software. The icidece of all asthma was compared with the icidece of occupatioal asthma reported to the Fiish Register of Occupatioal Diseases for the populatio of costructio workers, idustrial workers ad employed people of the etire coutry i 1995 [11]. We radomly selected a group of 100 asthmatic costructio workers ad examied their hospital records. The occupatio, atopy ad smokig habits at the time of diagosis were oted. Results I the Tampere Uiversity Hospital, there was a total of 3659 ew of asthma diagosed i the populatio betwee the ages of 20 ad 64 years i Of these, 147 were costructio workers ad 29 were paper mill workers. The asthma diagoses were extrisic asthma (42%), itrisic asthma (38%), other specified asthma (4%) ad o-specified asthma (16%). Table 1 shows the umber of people, the umber of ew asthma, ad the ORs with 95% CIs for the male workers i the three groups. The figures i Table 1 show a clear relatioship betwee costructio work ad a icreased risk of asthma. A slight dose respose relatioship is apparet

3 R. SAUNI ET AL.: ASTHMA IN FINNISH CONSTRUCTION WORKERS 529 Table 1. Odds ratios ad 95% CIs for male workers i the three occupatioal groups Age group (years) Pirkamaa Costructio workers i Pirkamaa Paper workers i Pirkamaa OR (95% CI) i the Pirkamaa populatio OR (95% CI) i the Pirkamaa populatio ( ) ( ) ( ) ( ) ( ) ( ) Total ( ) ( ) Table 2. Icidece of reported of occupatioal asthma i differet occupatioal groups i 1995 No. of reported of occupatioal asthma i 1995 a betwee the duratio of costructio work ad asthma frequecy. The OR betwee paper workers ad the geeral workig age populatio was 0.8 (95% CI = ) for wome ad 1.0 (95% CI = ) for me. The age-specific risk for asthma was almost the same for the paper workers as for the geeral populatio. I the oldest age group of paper mill workers, there was a icreased risk of asthma. The aual rate per 10 5 of asthma was 373 for the costructio workers, 216 for the paper workers ad 276 for the geeral workig age populatio of the Pirkamaa regio. Accordig to the hospital records (radom sample, 100 workers), there were positive fidigs i the prick tests of 45% of the asthmatic costructio workers. There were positive reactios to aimal dader i 27%, polle of trees i 19%, hay polle i 31%, house dust mite i 12% ad moulds i 2%. Thirty-eight per cet were active smokers, 31% were ex-smokers ad 25% had ever smoked. The distributio of the occupatioal titles of the asthmatic costructio workers was compared with that of the trade uio of costructio workers i Pirkamaa. There were more asthmatics amog the cocrete workers, ospecified costructio workers, isulators, pipe-fitters ad paiters (P < 0.05 for all these groups) tha i the other occupatioal subgroups. The icidece of No. of employed people i 1995 occupatioal asthma amog the costructio workers was lower tha that of the other occupatioal groups (Table 2). Discussio Aual rate per 10 6 Relative risk i costructio workers (95% CI) Costructio workers Idustrial workers ( ) All employed people i Filad ( ) Data are from the Statistical Yearbook of Filad 1991 except a Fiish Register of Occupatioal Diseases [11]. Our data idicate that the risk of asthma is icreased amog costructio workers whe they are compared with workers i the paper idustry or the geeral workig age populatio. This study was based o ewly diagosed asthma, ad thus selective withdrawal from the active workforce because of disease had ot yet sigificatly affected the umbers of costructio workers. However, it is possible that some of the workers may already have chaged their occupatio before the defiite diagosis, ad therefore the umbers may have give a uderestimate. The total icidece of asthma was slightly overestimated because the group of o-specified asthma also icluded of suspected asthma, which may later prove to be other diseases, e.g. chroic obstructive pulmoary disease. These comprised <10% of all the of asthma ad did ot iterfere with the compariso betwee differet occupatioal groups i Pirkamaa because all the were defied i the same way. The iclusio criteria for the costructio workers

4 530 OCCUPATIONAL MEDICINE were limited i our study to employees whose workig period was able to produce ew asthma i the 1990s. The defiitio for a costructio worker allowed a delay betwee the begiig of asthmatic symptoms ad the diagosis. If we had take ito accout oly workers who were still workig i the 1990s, the umber of ew asthma would have bee lower ad the risk slightly lower. However, the coclusio would have remaied the same; the risk of asthma amog costructio workers would have bee 1.5 (95% CI = ) times higher tha amog the geeral workig age populatio. Although costructio work was associated with a elevated risk of asthma, it is ot likely that costructio workers are predisposed to asthma for geetic reasos or because of lifestyle; istead, this trade, with physically demadig jobs, is available maily to workers with good respiratory health. Active smokig is kow to double the risk of asthma [16], but also cotradictory results have bee show [17,18]. I our study, asthmatic costructio workers smoked slightly more tha the geeral populatio, 38% beig smokers at the time of the diagosis of asthma, as opposed to 33% of the Fiish male ihabitats i 1995 [19]. Atopy also had o effect o the umbers, sice 45% of the costructio workers with asthma had atopy defied by positive fidigs i a prick test ad this rate is ot greater tha that of Fiish asthma patiets. The reported aual rate of occupatioal asthma was lower for costructio workers tha for idustrial workers or for all occupatios. From other studies, we kow that about oe-third of the eczema due to occupatioal exposure to chromium ad most of the asymptomatic of asbestos disease remai ureported amog costructio workers [12,13]. It is also a recogized fact that the coverage of occupatioal health services is half that of other idustries. This uderprovisio would also lead to the uder-reportig of occupatioal asthma. Thus, it is possible that occupatioal dusts or chemicals cause more asthma tha idicated by statistics. O the other had, cliical experiece idicates that oly a few of asthma meet the strict criteria of a occupatioal disease [20,21]. I additio, costructio workers are exposed to may sesitizig agets, ad they are also exposed to may irritats. These risk factors may iteract to produce the work-related respiratory outcome of exposed workers. Therefore, it ca be difficult to defie a sigle causative aget for asthma at the idividual level [5]. This o-specific, possibly irritat effect of the workig eviromet may explai the excess of risk for geeral asthma. I additio, exposure to sesitizig agets at work may aggravate previously existig asthma or slight asthma symptoms that develop as a result of other types of exposure. Because this worseig effect possibly causes problems for costructio workers, they may actively seek the aid of a physicia ad medicatio, the result beig higher rates i asthma statistics. The results idicate that isulators, pipe-fitters, cocrete workers, o-specified costructio workers ad paiters have a higher risk of asthma tha other costructio workers. I a ew Fiish study based o atioal statistics, a elevated relative risk was foud for asthma amog electrical workers, woodworkers, paitig ad lacquerig workers, ad other costructio workers [5]. I a further aalysis of this study, published i 2002, all Fiish male costructio idustry workers ad all those employed i admiistrative work were followed for asthma icidece through a register likage i 1986 through Age-adjusted relative risks were icreased i early all costructio occupatios studied, but the relative risk (RR) was highest amog welders ad flame cutters (RR = 2.34), asphalt roofig workers (RR = 2.04), plumbers (RR = 1.90), ad bricklayers ad tile setters (RR = 1.83) [22]. The results of this study are similar to our results, ad stregthe the observed associatio betwee exposure i costructio work ad risk of asthma. Paiters may also be exposed to specific sesitizers, such as diisocyaates, isothiazolioe, formaldehyde or epoxides. I a previous study, paiters were foud to be at icreased risk of airflow obstructio [23]. Wieslader et al. [24] foud that the icidece of self-reported asthma amog paiters usig water-based paits was slightly higher tha that of a idustrial populatio. I a study of isulatio workers, occupatioal exposure did ot seem to affect the risk of respiratory symptoms, but there was a positive iteractio betwee occupatioal exposure ad icreased airway hyperreactivity [25]. I a America study amog carpeters, exposure to cemet, drywall ad demolitio dusts was associated with asthma whe Burey s defiitio was used [26]. Coclusios This study shows that the risk of asthma i costructio workers is higher tha i the geeral workig age populatio, although the umber of reported of occupatioal asthma is lower. Additioal studies are eeded to determie the causative agets of asthma i costructio work ad the role of the effect of osesitizig irritats o the developmet of asthma. Work-related asthma seems also to iclude asthma with mechaisms other tha sesitizatio. Ackowledgemets This ivestigatio was supported by the Medical Research Fud of the Tampere Uiversity Hospital ad The Tuberculosis Foudatio of Tampere.

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