Respiratory symptoms andimpairmentinshipyard welders … · radiographs were available on 332 men. Amongthe menaged 50-69 the prevalence ofpersistent cough and phlegm (chronic bronchitis)

British Journal ofIndustrial Medicine 1989;46:292-301

Respiratory symptoms and impairment in shipyardwelders and caulker/burnersJ E COTES,' 2 E L FEINMANN,' * V J MALE,3 F S RENNIE,' C A C WICKHAM4From the Royal Infirmary, Sunderland, ' Division ofEnvironmental and Occupational Medicine,2 MedicalSchool, Newcastle upon Tyne NE2 4HH, Northern Regional Health Authority, Newcastle upon Tyne, andDepartment ofApplied Statistics,4 University ofReading, Reading, Berks, UK

ABSTRACT All 607 men, aged 17 to 69, comprising a stratified sample of workers from one shipyardcompleted a respiratory questionnaire, clinical examination, and detailed spirometry. Chestradiographs were available on 332 men. Among the men aged 50-69 the prevalence of persistentcough and phlegm (chronic bronchitis) was 40%, of wheeze on most days 25%, and unduebreathlessness on exertion 25%. After allowing for age the relative risk of welders and caulker/burners having these symptoms were respectively 2-8, 2-2, and 3-1 compared with other shipyardtradesmen. The effects were of comparable magnitude to and interacted with those of currentsmoking. Among the welders and caulker/burners who smoked, the relative risk of developingchronic bronchitis or undue breathlessness was related to the average fume exposure; the relative riskof wheeze was related to the average fume exposure in all smoking categories, with the strongestassociation in the ex-smokers. The occurrence of wheeze was also associated with a history ofprevious metal fume fever. A history of pleurisy but not of pneumonia was related to the fumeexposure in.the welders. After allowing for age and stature, forced expiratory volume (FEV,) was onaverage higher in young welders (age < 30) than other tradesmen. In welders and caulker/burnerswho were current or ex-smokers, FEV, and PEF were reduced in relation to the average fumeexposure (mean reductions respectively 0 25 1 and 0 99 1 s-'). The FEV,% (of forced vital capacity),the flow rates at small lung volumes (MEF50%Fvc and MEF25%FVc), the mean transit time, and itsstandard deviation were also reduced by fume exposure or the declines with age were increased, orboth. No impairment was demonstrable in the non-smokers and many men had given up smokingwith apparently beneficial results. The occupational component ofthe respiratory impairment relatedmainly to exposures in the past; information was needed on the effects of present conditions in theindustry.

In NE England ships are made from mild steel. Thesheets are joined by welders who normally useflux covered electrodes (manual metal arc welding).Burners, whose trade is linked to that ofcaulkers, buffand burn offany metal protruding from the completedwelds; they also gouge and cut the welded plates. Bothgroups of tradesmen are exposed to fumes from theweld metal (iron with an admixture of other sub-stances), flux, coating materials, and solvents; the menmay also inhale carbon monoxide, nitrogen dioxide,

*Dr Feinmann died on 25 July 1983.

Present address: CACW: MRC Environmental Epidemiology Unit,University of Southampton, Southampton, Hants.

Accepted 23 May 1988

ozone, and cigarette smoke. Asbestos from laggingwas formerly an additional hazard but this is nowmainly a problem of ship repairing and breaking.Respiratory protection is by local exhaust ventilationor air supplied respirators; these measures are ofrecent origin and not universally applied.Compared with other shipyard tradesmen the wel-

ders have a raised standardised mortality ratio frompneumonia, and the caulker/burners from pneumoniaand chronic bronchitis.' The forced expiratory volumehas been reported as either normal2 or reduced bywelding fumes in association with smoking.34 Theevidence up to 1979 has been reviewed by Newhouseand Murray.5 Recent studies have suggested that atleast some of the respiratory morbidity and mortalityamong welders is due to asbestos6 whereas, except in

292

copyright. on O

ctober 19, 2020 by guest. Protected by

http://oem.bm

j.com/

Br J Ind M

ed: first published as 10.1136/oem.46.5.292 on 1 M

ay 1989. Dow

nloaded from

Respiratory health ofshipyard welders and caulker/burners

the case of stainless steel,7 the role of welding fumes isbelieved to be relatively unimportant.8 In one studywhere the opposite conclusion was reached the controlgroup was inappropriate.9 Among ship maintenanceand repair workers at Devonport dockyard, weldershad prolonged sickness absences from respiratoryinfections.'° Compared with these men the welderswho build ships may experience higher concentrationsof fumes from working in the double bottom of shipsand other confined spaces. Among such men theforced expiratory volume and transfer factor of non-smoking welders have been reported as reduced" butsampling was not systematic and the controls wereoffice staff not tradesmen. The present study at thesame shipyard assesses the situation in greater detail.

Subjects and methods

The shipyard population was defined as all men on thepayroll at 31 December 1978 plus the 37 welders whohad left during the preceding nine years. Of the latter,14 were dead, 10 had retired, and 13 had left for otherreasons. A sample was drawn comprising all men aged45 or over whose current or last occupation was as awelder or caulker/burner, 50% ofwelders and caulker/burners aged less than 45, all the tack welders, and 5%of other tradesmen, including riveters, fitters, elec-tricians, and carpenters. Sampling was by randomselection. Subsequently all foreman welders and plum-ber welders (20 of each) and two plater operators offairing equipment were added to the survey popula-tion. After the survey the men who had ever been awelder, or failing that, a caulker/burner, were includedunder one ofthese headings (table 1). Information wasincomplete (usually from omissions during adomiciliary visit) in approximately 5% of men; asimilar proportion refused to participate. Subjectscompleted an employment questionnaire, then wereseen by one of four physicians (ELF, VJM, JHRR,

Table 1 Study population analysed by trade

No withcomplete

No in sample data*

Age range (y) 17-44 45-70 17-70 17-70Welders:

Current 105 179Ex-employees - 37 361 353Foremen 20 }Plumbers 20

Caulker/burners 44 70 114 117Tack welders 21 85 106 56Other tradesmen 105 81

Total 686 607t

*After reclassifying as welders or caulker/burners men whosubsequently moved to other trades.tOf 79 lapses, 14 were dead, 34 had refused, and 31 had incompletedata.

FSR). They filled in a detailed questionnaire based onthe MRC questionnaire on respiratory symptoms andMcMillan's dockyard survey questionnaire'0; ques-tions were asked on anginal symptoms. The menunderwent a clinical examination.

Stature was measured with a Harpendenstadiometer, body mass with a calibrated beambalance, and skinfold thickness at four sites withHoltain skin calipers; the measurements were used toestimate fat free mass and percentage body fat.'2Trunk dimensions were also obtained but did notcontribute usefully to the analysis.The forced expiratory volume (FEV,) and vital

capacity (FVC) were obtained by one of two ex-perienced observers each using a McDermott bellowsspirometer with digital display and incrementalvolume output (10 ms increments,'3); the spirometerswere calibrated four times daily. The subjects madetwo practice expirations, then three technically satis-factory results were obtained, and the highest value foreach index was analysed. Spirometric results obtainedon 27 men during domiciliary visits by other observerswere not included in the analysis (see results). Flowvolume curves were displayed on a JJXY recorder andinspected at the time for shape and consistency. Theinformation was recorded on a Sony 2 channel taperecorder. Tapes were analysed using a HewlettPackard 9825 computer and printer. Peak expiratoryflow rate was the mean over 30 ms (PEFR); other flowrates were taken at the point when 50% and 25%of FVC remained to be expired (MEF5O%FvC andMEF25%FVc respectively). Transit time indices were themean (MTT) and the standard deviation (SDTT).Expiration was considered to have started afterexpiration of 100 ml and to have ended when thevolume expired in 0-5 s did not exceed 25 ml or, for thetransit times, when the expiration had continued for6 s. The two curves having the highest FVC wereanalysed; for the flow indices the higher of the tworesults was used, provided that the curves were ofacceptable shape (see results), the FVCs agreed towithin 5%, and the peak flow rates to within 10%.When this criterion was not met the result was takenfrom the expiration with the higher FVC. The transittime indices were taken from the expiration with theshorter mean transit time of the two which wereanalysed."

Chest radiographs were available for 332 men; mostwere taken during a radiographic survey in 1977 andthe remainder at the time of the study-that is, twoyears later. Three independent observers read eachfilm for round and irregular small opacities and otherabnormalities using the ILO International Classifica-tion of Pneumoconioses.'5 Majority readings weresubsequently extracted by the authors and theprofusion scores 0/- and 0/0 were amalgamated.

293

copyright. on O

ctober 19, 2020 by guest. Protected by

http://oem.bm

j.com/

Br J Ind M

ed: first published as 10.1136/oem.46.5.292 on 1 M

ay 1989. Dow

nloaded from

294A year after the survey, a subsample comprising the

men with wheeze on most days, breathlessness grade 3or above, or impaired lung function were reassessed,together with a sample of other men. The resultsobtained were used to check the stability of those ofthe main survey. The survey results after checkingwere transferred to an ICL 2966 computer runningunder the George 3 operating system. A preliminarydescriptive analysis was undertaken and for each manindices of exposure to fumes as a welder or caulker/burner and reference values for FEV, were cal-culated.'2 The exposure indices for welders were WIever a welder, W2 years welding, W3 total fumeexposure; this was the sum of the duration of eachperiod of work as a welder multiplied by the propor-tion of time spent in confined spaces (< 25% of time,25-75%, >75% of time), W4 discounted fumeexposure was as for W3 but with additional weightinggiven to exposure in the distant past, W5 accumulatedfume exposure was as forW3 but additional weightinggiven to recent exposure.'6 Average exposure (AE) wastotal fume exposure (W3) divided by duration ofexposure. Similar indices were calculated for caulker/burners (C/B 1-5) and tack welders. Ever a welder orcaulker/burner provided an overall index of fumeexposure.

Rtsults were entered into a multivariate analysis aseither continuous or dummy variables (present orabsent). The latter included exposure indices Wl andC/B 1, smoking or ex-smoking, previous pneumonia orpleurisy, asbestos exposure, and cough with phlegmfor more than three months in the year; the lattersymptoms were evidence for simple chronic bronchitis(MRC,'7). Wheeze was scored on the 3 point scale,(3) absent, (2) present occasionally, or (1) present onmost days or nights. Breathlessness was analysed usingan extended scale based on the clinical grades ofFletcher.'2"8 Multiple regression and logistic regres-sion analyses were performed using an IBM 370computer, the computer package GLIM (NumericalAlgorithms Group, Oxford), the Statistical Packagefor the Social Sciences (SPSS) of the University ofMichigan,'9 and BMDP statistical software.20 Thedependent variables in the regression analyses were thelung function indices, the category ofpneumoconiosis,and the respiratory symptoms. The independent vari-ables were stature, mass/stature2, age, smoking, ex-smoking, previous chest illnesses, and exposure toasbestos; the effects ofexposure to fumes from weldingor burning were assessed in terms of average exposurefor welders and caulker/burners alone, and of trade asa welder or caulker/burner when comparison wasmade with men in other trades. Tack welders wereexcluded from the latter comparisons. For analysesincluding interaction terms the variables, age andaverage exposure, were centred about their meanvalues.

Cotes, Feinmann, Male, Rennie, Wickham

Multiple regression analysis was performed using aforward stepwise method, the independent variablegiving the largest reduction in the residual sum ofsquares being selected first. The exception was theexposure variable which was fitted after the otherimportant variables had been included in the model.The analysis was carried out both without and withallowance for possible interaction between age, smok-ing, and exposure. The regression coefficients wereconsidered to be significant at the 5% level ofprobability. The results of the logistic regression werereported in terms of the relative risk compared withunity which implied no contribution from the variablein question.

Results

DESCRIPTION OF SUBJECTSThe welders or caulker/burners in the survey popula-tion had a wide range of exposure to fumes. Theexposure indices W2 through to W4 and CB2 to CB4were highly correlated with age; the indices W5 andCB5 were weakly correlated, whereas the averageexposure (AE) was independent of age. Accordinglythis latter index was used in the analysis; the meanvalues and standard deviations for welders andcaulker/burners respectively were 1-93 (0 60) and 1 87(0 54) units. The interaction term, AE x age (based oncentred variables), was independent of age and onlyweakly correlated with AE (r = 0 095) so all threeterms could be included together in the multipleregression analyses. Among the survey populationthere were no former coalworkers or quarry men.Exposure to asbestos occurred from working along-side laggers (399 men), using asbestos cloth (79 men),working as a limpet sprayer (53 men), or working as alagger (35 men). Of the welders and tack welders, 71%had experienced ray burns or arc eye; 35% of thewelders and 29% ofthe caulker/burners had had metalfume fever associated with exposure to zinc. Fifty sixper cent of participants were current cigarette smok-ers, 16% had never smoked (table 2). The amountcurrently smoked was independent of age and trade(mean value 21-7 g/day, range 1-70 g). The proportionof ex-smokers among the survey population (table 3)and among the welders but not the caulker/burnersseparately was significantly higher than expected formen in this social class in the United Kingdom. Of themen forwhom there were chest radiographs, 22 (6 6%)had simple pneumoconiosis grade 2/1 or above. Ahistory of pleurisy or pneumonia or chest injury orhaemoptysis was given by 8-16% of men. Four percent experienced exercise related discomfort sugges-tive of angina; 12 of these men (out of 23) weresubsequently studied in detail and notable ischaemicheart disease was present in one. Three per cent of themen had had tuberculosis and 25% had kept pigeons

copyright. on O

ctober 19, 2020 by guest. Protected by

http://oem.bm

j.com/

Br J Ind M

ed: first published as 10.1136/oem.46.5.292 on 1 M

ay 1989. Dow

nloaded from

Respiratory health ofshipyard welders and caulker/burners

Table 2 Percentage ofrespiratory symptoms and smokinghabits by age group*

Age group (y) 20-29 30-39 40-49 50-59 60-69No 64 86 160 262 26Cough and phlegm> 3/12 21-9 20 9 32 5 37-8 50 0t

Wheeze:(i) 26-6 36-0 39-4 41 2 30-8(ii) 7-8 16 3 16 9 26-3 26 9tTotal 34-4 52-3 56 3 67.5 57-7

Breathlessness:Grade 3 16 7-0 13-8 214 19 2tGrade 4-5 0 1.1 06 4-2 19-2tTotal 1 6 8 1 144 25-6 38-4

Smokers:Cigarettes 57 8 46-6 53-1 60-1 61 5Other 3-1 2-3 1-3 2-1 3 9Total 609 48-9 54-4 62 2 654

Ex-smokers 17-2 24-4 25-6 29-0 26-9Never smoked 21-9 26-7 20-0 8-8 7-7

*Nine men aged < 20 are omitted from this table.tSignificant relation to age (p < 0-05); a more complete analysis isgiven in the text.

or budgerigars, but none had evidence ofbird fanciers'lung. Chronic bronchitis (MRC) was recorded by 33%ofmen, 21% recorded wheeze on most days or nights,18% admitted to breathlessness grade 3 or more, and11% had a reduced FEV, (< 2 SD). The prevalence ofthese abnormalities was related to age (table 2 and fig1). Mean results for some anthropometric and lungfunction measurements are given in table 4.

RESPIRATORY SYMPTOMSThe principal determinant of chronic bronchitis wassmoking which, after allowing for age and trade, wasassociated with a threefold increased risk comparedwith non-smokers and ex-smokers (relative risk 3-2,95% confidence limits 21-46). The risk of chronicbronchitis increased with age and with physique, theshort heavy subjects being more at risk than subjectswith a low value for mass/st2. After allowing for ageand current smoking, work as a welder or caulker/burner was associated with an increased risk of

Table 3 Numbers ofmen in different smoking categories byage groups compared with United Kingdom averagesforsocial class III manual workers (Tobacco Advisory Council,1980)

Age (y)

25-34 35S-49 50-64

Current smokers: (any product)Observed 40 117 177Expected 44-0 123-4 189-7

Ex-smokers*Observed 16 56 82Expected 9.4 42-9 62-5

Non-smokersObserved 15 47 25Expected 17 8 49-5 32-7

*Excess of ex-smokers was significant (X2 = 21 52, p < 0-001).

chronic bronchitis compared with other trades(relative risk 2-8 (1 4-5.5)). In addition there wassignificant interaction between the effects of smokingand of welding fumes. Among welders and caulker/burners who smoked, the increased risk of chronicbronchitis was related to the average fume exposure.For the combined non-smokers and ex-smokers, therisk associated with the welding trades was alsoincreased, but the increase was not relative to theaverage exposure and there was no association withtrade when ex-smokers and non-smokers wereexamined separately (table 5 and fig 2). The non-smoking other tradesmen, however, comprised only19 men. Previous pneumonia or pleurisy were sig-nificant antecedents of chronic bronchitis. Theoccurrence of pneumonia was related to age but wasindependent of the other variables, including fumeexposure. Pleurisy was related to age in the welders;for the whole shipyard population it was also relatedto smoking, stature, and systolic blood pressure. Inwelders, after allowing for age, the prevalence ofpleurisy was related to the average exposure.

Chronic bronchitis50O

40--l

y 30-'a" 20-

10-

0

40-

i 30-

> 20-Goa-

10-

0

.

20 30 40 50 60 70

00

Occasional0

0

0 0 0Most days

0

0

io 3b 4b 5bAge group (y)

60 *70

Fig 1 Prevalences ofchronic bronchitis, breathlessnessgrade 3 or above, and wheeze occasionally or on most days inrelation to age.

295

copyright. on O

ctober 19, 2020 by guest. Protected by

http://oem.bm

j.com/

Br J Ind M

ed: first published as 10.1136/oem.46.5.292 on 1 M

ay 1989. Dow

nloaded from

296

Table 4 Mean values and SDfor lungfunction and relatedindices in the shipyardpopulation. Mean valuesfor thewelders and caulker/burners whose results were included inthe analysis summarised in table 8 are given in parentheses (n= 360-371 for the different indices)

n Mean SD

Age (a) 575 46 0 (47 0) 10-8Body mass (kg) 568 75.7 (75 6) 11 7Stature (m) 574 1-71 (1-72) 0-07Body mass/st2 (kg m2) 568 25 7 (256) 3 5Forced expiratory volume (1) 575 3-10 (3 05) 0-84Forced vital capacity (1) 575 4-36 (4-33) 0 90FEV,/FVC (%) 575 70-6 (70-0) 10-3Peak expiratory flow (I s-') 575 8-88 (8 88) 2-46Maximal expiratory flow: (I s-')MEFO0%Fvc 572 3-62 (3-56) 1-60MEF25%Fvc 573 1-16 (1-10) 0-70

Mean transit time (s) 553 0-785 (0-800) 0212SDTT (s) 553 0-98 (1.00) 0-26

The occurrence of wheeze occasionally and wheezeon most days or nights were initially analysedseparately but with similar results; the two were

combined for the following account. Wheeze was

related to age, current smoking, systolic blood pres-

sure, chronic bronchitis, and previous metal fumefever. From logistic regression analysis of wheeze on

age, current smoking, and trade, the relative risk forcurrent smokers compared with non-smokers and ex-

smokers was 2-7 (1 9-3 9), and the relative riskassociated with the trade of welder or caulker/burnerwas 2-2 (1 3-3-7). In addition, for all smokingcategories of welders and caulker/burners there was a

significant dependency of wheeze on average fumeexposure. There was also significant interactionbetween smoking and trade. Considering individualsmoking categories the relation with fume exposure

was strongest in the case of caulker/burners who were

ex-smokers (table 6); it was no longer significant whenallowance was made for co-existing chronic bron-chitis. Among welders and caulker/burners, after

50- S

"'u 30 ExSS S

c2 S5x

xSS

W+C/B OT W+C/B OT W+C/B OTChronic Wheeze Breathlessnessbronchitis most days 3 grade 3

Fig 2 Prevalences ofrespiratory symptoms in men who hadever smoked, subdivided by trade (welders and caulker/burners (W + C/B) or other tradesmen (OT)) and bysmoking category (smokers (S) or ex-smokers (ExS)).

Cotes, Feinmann, Male, Rennie, WickhamTable 5 Relative risk ofchronic bronchitis in welders (W)or caulker/burners (C/B) compared with other tradesmen(OT). Allowance madefor age

Relative risk with 95% confidence interval

Smokers Ex-smokers Non-smokers

W > OT 2-1(1-0-4-4) TNS TNSCB > OT 27 (1-2-60) TNS TNS

WorC/B > OT* 2-3 (11-4-8)t 3-4(1.1-10-6)

TNS = Term not significant.*For all subjects allowing for age and current smoking 2-8 (1.4-55).tSignificant association with average fume exposure in welders andcaulker/burners, independent of metal fume fever.

allowing for age, smoking, and average exposure, ahistory ofmetal fume fever carried an increased risk ofwheeze (relative risk in smokers and non-smokers as agroup, 2-3, 14-3-8).The grade ofbreathlessness in the survey population

was associated positively with chronic bronchitis, age,mass/stature2, current or ex-smoking, pleurisy, exer-tional chest discomfort, and wheeze; it was negativelyassociated with stature. After allowing for age, stature,mass/stature2, and chronic bronchitis, the risk ofbreathlessness grade 3 or above was increased inwelders and caulker/burners compared with othertradesmen. The risk was not independent of smokingcategory; among current smokers the relative risk was3-2 (1 1-9-9) but there was no detectable increased riskfor non-smokers or ex-smokers, either separately or incombination (table 7). For the welders and caulker/burners who smoked the increased risk of breathless-ness was related to the average fume exposure. Thebreathlessness was associated with chest discomfortduring exercise.

X RAY CATEGORY OF SIMPLE PNEUMOCONIOSIS(SMALL OPACITIES)The 332 men on whom chest radiographs wereavailable were predominantly welders (63%), caulker/Table 6 Relative risk ofwheeze in welders (W) or caulker/burners (C/B) compared with other tradesmen (OT).Allowance madefor age

Relative risk with 95% confidence interval

Smokers Non-smokers Ex-smokers

W > OT 1-8 (0-9-3-7) 3 2 (0 7-12 8) 2-9 (0-8-10-0)CB > OT TNS TNS 4-4(1-1-17-6)W or C/B > OT* TNS 2-7 (0 8-9-4), 3-1 (1-2-7-8)t

1-6 (1-02-7)t

TNS = Term not significant.*For all subjects allowing for age and current smoking 2-2 (1-3-37).Previous metal fume fever also contributed significantly.tSignificant association with average fume exposure in welders andcaulker/burners, independent of metal fume fever.

copyright. on O

ctober 19, 2020 by guest. Protected by

http://oem.bm

j.com/

Br J Ind M

ed: first published as 10.1136/oem.46.5.292 on 1 M

ay 1989. Dow

nloaded from

Respiratory health ofshipyard welders and caulker/burnersTable 7 Relative risk ofbreathlessness grade 3 or above inwelders ( W) or caulker/burners (C/B) compared with othertradesmen (OT). Allowance madefor age

Relative risk with 95% confidence interval

Smokers Ex-smokers Non-smokers

W > OT 29(10-98) TNS TNSCB > OT 5-6(14-21-2) TNS TNS

Wor C/B > OT* 32 (1-1-9-9)t TNS

TNS = Term not significant.*For all subjects allowing for age 3-1 (1-3-7-7).tSignificant association with average fume exposure in welders andcaulker/burners, independent of metal fume fever.

burners (19%), and tack welders (5%). They were onaverage similar to the remainder in respect of age,fume exposure, FEV,, and all the attributes given intable 2. Before statistical analysis the results for 13men whose chest radiographs showed notable abnor-malities other than pneumoconiosis were excludedand 12 data sets were excluded on account of one ormore missing items. Among the remaining 307 menwere 20 in whom the profusion of small opacities was2/1 or above; in 13 the opacities were round, in sixpredominantly round, and in one predominantlyirregular. Among the exclusions were two withcategory 2/1 or above; in both the opacities wereround. The profusion of small opacities was relatedto age and exposure to welding fumes; together thesevariables accounted for 18% of the variance. Therewere no associations with smoking, respiratory symp-toms, or impaired lung function.

LUNG FUNCTIONComplete results were obtained on nearly all subjectsother than the 27 men who were seen at home; on thesemen, flow volume curves were not recorded. Inaddition, in many instances the FEV, or FVC wasmaterially lower than at the 12 month follow up.Accordingly, the results for men seen at home were notincluded in the analysis. Also excluded were the flowvolume results for 22 men with atypical curves; the

latter exclusions did not influence the findings. TheFEV, was related positively to stature and negativelyto age, current or ex-smoking, systolic blood pressure,chronic bronchitis, wheeze, previous pleurisy, andprevious pneumonia. Fume exposure was also relatedto some of these variables (see above) so whenexamining its possible association with impaired lungfunction allowance was made only for the independentvariables age, stature, and smoking. The analysis wasconfined to the welders and caulker/burners as in thesemen the lung function could be related to the averagefume exposure; significant associations were observedin the smokers and ex-smokers as separate groups butnot in the non-smokers. Among welders and caulker/burners who were smokers or ex-smokers the averagefume exposure contributed to the description ofall theindices obtained by dynamic spirometry except FVC;either or both the absolute level was reduced and thedecline with age was increased. When the wholeanalysis was repeated including the non-smokers, asimilar result was obtained (table 8). For most of theindices of lung function the ex-smokers had signifi-cantly better lung function than the smokers. Theadverse effect of smoking, however, was not related tothe number of cigarettes currently smoked a day.Among the smokers the results did not differ asbetween the welders and caulker/burners. By contrast,among the non-smokers and ex-smokers, after allow-ing for age and stature, the welders had higher valuesfor peak expiratory flow rate (APEF 0-96 1 s1') andforced expiratory volume (AFEV, 0-23 1) than thecaulker/burners. In addition, among the shipyardworkers aged less than 30, the FEV, was 9% higheramong the welders than the other tradesmen, despitethe two groups having similar age, stature, andtobacco consumption.

Discussion

This study describes the respiratory health of currentshipyard workers and surviving welders or caulker/burners from among those who had left within the

Table 8 Multiple regression equations describing indices ofairflow limitation in welders and caulker/burners who had eversmoked. Age andAE were centred about their mean values (table 4)c (For abbreviations, see methods)

FEV, FVC FEV%* PEF MEFa%FVc* MEF2%FVC* MT7' SDTTRegression coefficient (1) (1) (%)),s (l,s') (Is) (s X 103) (s X 10)

Age (y x 10-3) - 36 - 34 -415 - 76 - 63 -36 7-2 8-9Stature (m) 5-03 7-70 -15 2 813 4 21 1-41 430 -

Average exposure (AE) -0-13 - -3-28 - 0-52 - - 66AE x age(x 103) - - -304 - -31t -lOt 5-6 4.7tIf ex-smoker - - 294 0-57 0-45 018 -52 - 52Constant -3-40 -7-28 95-2 -1 73 -0-86 0-26 76-2 1019SEE 0-58 0-62 9-37 1-83 1-39 050 200 236R2 (%) 49-6 53-8 18-2 26-3 23-0 36-4 13 2 11-6

*Exposure terms also significant with non-smokers included in the equation (smoking scored 0, 1, 2 for non, ex-, and current smokers).tTerm significant in presence ofAE which was not itself significant.

297

copyright. on O

ctober 19, 2020 by guest. Protected by

http://oem.bm

j.com/

Br J Ind M

ed: first published as 10.1136/oem.46.5.292 on 1 M

ay 1989. Dow

nloaded from

298preceding nine years. It throws no comparable light onthe men who died during the nine years or those wholeft before that. In addition, no information wasobtained on the 5% ofmen who refused to participate;however, their omission was unlikely to havematerially influenced the result. The exclusion fromthe analysis of lung function of results obtained atdomiciliary visits led to the omission of some subjectswith material respiratory impairment, but this wasnecessary if only reliable information was to beanalysed. The exclusion of current tack welders fromcomparisons between men who had ever been weldersor caulker/burners and men in other trades was alsonecessary on account of the fume exposure of tackwelders being intermediate between those of the maingroups. The effects of their exclusion were mainlyquantitative rather than qualitative.

QUALITY OF INFORMATION INCLUDED IN THEANALYSISThe occupational histories were checked byoccupational nurses in the shipyards and again by thechest physicians at clinical interview. Comparisonwith information obtained subsequently on a sub-sample of men showed that estimates of time spentwelding or caulker/burning in confined spaces(<25%, 25-75%, >75%) were rather variable butotherwise the occupational histories were consistent.This was also the case for the answers to respiratoryquestions in men whose circumstances had notchanged in other respects-for instance, smokinghabit or medical treatment. The anthropometricmeasurements were made using standard procedures;some variation may have occurred in themeasurements of skinfold thickness and chest wall andsternal lengths but these indices did not contributeusefully to the results. The spirometry included in theanalysis was performed by two experienced observersusing identical equipment which was calibrated fourtimes daily. The three x ray readers were also experien-ced; they used common standard and trigger films.Thus the information obtained was of good qualityapart from the indices of exposure. The latter, as wellas having a rather poor reproducibility, also made noallowance for the individual welders adoptingdifferent postures or positions for the exhaust ventila-tion hose. An attempt to improve the exposure indicesby incorporating information on heat exposure-forinstance, arc eye or skin burns-was unsuccessful asthe latter features failed to identify heavily exposedmen and no systematic personal sampling had beencarried out. Nevertheless, relatively crude informationof this type has been adequate to identify exposureeffects in other studies.

Cotes, Feinmann, Male, Rennie, WickhamASPECTS OF ANALYSISThe original survey population was enlarged by theinclusion offoreman welders and plumber welders; theformer had previously been welders and their exposureto fume was estimated with an accuracy similar to thatfor other men. The plumber welders had a differentexposure but they constituted fewer than 6% of menclassified as welders. Nine men were aged 20 or less,hence their lungs were still growing and smaller thanpredicted using the adult model relating lung functionto age. Only three were exposed to fumes (2 welders, 1caulker/burner), however, so the error this introducedinto the analysis was small.The numbers ofmen in subgroups defined by trade

and smoking category were adequate for the analyses,except in the case of non-smoking other tradesmen;this group comprised only 19 men.A difficulty with the analysis was the high correla-

tion that obtained between age and many of theexposure indices, also between the interaction termsand their component variables. Principal componentregression analysis was considered as a means ofovercoming this source of error2' but rejected as theresulting factors could not be interpreted precisely. Inthe event error was minimised by confining theanalysis to uncorrelated variables. To this end averageexposure was used instead of total exposure and theconstituents of interaction terms were centred abouttheir mean values.

RESPIRATORY SYMPTOMSShipyard workers over the age of 50 were found tohave significant respiratory morbidity includingchronic bronchitis in 40% of men, wheeze on mostdays or nights in 25%, and undue breathlessness onexertion also in 25% of those in this age group. Theseprevalences were similar to those observed in the 1950sby Higgins and Cochrane in coalminers and foundryworkers' but they were higher than have been repor-ted in most other series.23 Breathlessness was the men'sprincipal complaint. It resulted from many factors,some of which, such as chronic bronchitis and pleur-isy, were themselves related to occupational fumeexposure. Omitting these and after allowing for ageand stature, there was a significant association be-tween breathlessness and trade as a welder or caulker/burner. The association was independent of chronicbronchitis but was related to whether or not the menhad ever smoked. Among welders and caulker/burnerswho were current smokers the likelihood ofbreathless-ness was related to the fume exposure. The possiblereasons for the breathlessness are considered below.

Chronic bronchitis is traditionally associated withoccupations entailing exposure to dusts and fumes; theaverage prevalence is usually reported as about doublethat in other occupations24 but less than that due to

copyright. on O

ctober 19, 2020 by guest. Protected by

http://oem.bm

j.com/

Br J Ind M

ed: first published as 10.1136/oem.46.5.292 on 1 M

ay 1989. Dow

nloaded from

Respiratory health ofshipyard welders and caulker/burnerssmoking. In the present study the relative risk ofchronic bronchitis for welders and caulker/burnerswas 2-8 times that for other tradesmen, and compara-ble with that of smoking. There was significantinteraction between these two effects such that thelikelihood of chronic bronchitis was significantlyrelated to the average fume exposure in the smokersbut not the non-smokers or ex-smokers, eitherseparately or in combination (table 5). Thus there wasstrong evidence that the fumes affected the lungs ofsmokers and that the large number of welders whoabandoned smoking benefited by so doing. Thispossibility was suggested by Barhad and colleagues.25Chronic bronchitis, together with age and smoking,were the principal factors associated with wheeze.After allowing for age and smoking, however, theoccurrence of wheeze was related to the fumeexposure; the association was strongest for the ex-smokers which suggested that, unlike in the case ofchronic bronchitis, abandoning smoking did not bringrelief from the fume related component of this symp-tom. Wheeze was more common in men with previousmetal fume fever. Experience of this condition wasreported equally often by welders and caulker/burnerswho had ever smoked but by rather more non-smoking welders than caulker/burners. The occur-rence of metal fume fever was independent of theestimated average fume exposure but the estimate wasprobably influenced more by recent than previousexposure, so a real association could have been missed.Information on atopic status could have thrown lighton the mechanisms. The study failed to confirm thatwelding fumes contributed to an increased prevalenceof pneumonia, though this had been expected in thelight of other evidence.' 2627 The prevalence of pleurisywas increased, however. This was not due to con-current exposure to asbestos. In addition, siderosisand sensitisation arising from keeping pigeons orbudgerigars appeared not to have contributed to anyof the abnormalities observed.

LUNG FUNCTIONThe welders and caulker/burners who had eversmoked were found to have exposure related narrow-ing of both large and small airways. The impairmentassociated with exposure was the same at all ages in thecase ofFEV, andPEF but was greater in the older thanthe younger subjects for the FEV%, maximalexpiratory flow rates at small lung volumes, and thetransit time indices. For all but the FEV,, where theseparate results for welders and caulker/burners werenot significant, similar relations with fume exposurewere obtained for smokers and ex-smokers and wel-ders and caulker/burners separately. In addition, theinclusion of non-smokers did not alter the significanceof the coefficients on exposure, except marginally for

FEV, (p = 0 053). Thus the evidence for weldingfumes contributing to airway narrowing in smokersand ex-smokers was internally consistent. Theevidence for a similar effect in non-smokers was weakbut this could have been due in part to this group onlycomprising 73 men. Among the smokers and ex-smokers, the average reductions in FEV, and PEFassociated with fume exposure were respectively 0-25 1and 099 1 s' which were 8% and 11% of the meanvalues. These changes were of similar magnitude tothose associated with smoking compared with non-smoking (respectively 0-23 1 and 0-88 1 s-') andsufficient to cause breathlessness on exertion in someindividuals,n especially those who also had chronicbronchitis. For the other indices, the apparentbronchoconstrictor effect of fume exposure in menwho had ever smoked increased with age. This couldhave been due to both the cumulative effect ofprolonged exposure to lung irritants and higher fumeexposures in the past. Similar changes would then havebeen expected for the FEV, and PEF. That these werenot observed might have been due in part to confound-ing factors. Thus the young welders had a higher meanFEV, than the other tradesmen and among the currentnon-smokers, the welders had higher levels of PEFthan the caulker/burners. These changes could havebeen due in part to shipyard recruits of robustphysique having been selected as welders and towelding possibly exerting a training effect on theaccessory muscles of respiration. Selective loss fromthe shipyard population of men with respiratoryimpairment appeared not to have been a materialfactor in the years immediately preceding the studywhen the labour turnover was small. It became sosubsequently, however, during a period when manymen were laid off (paper in preparation) and itsoperation during the earlier period cannot altogetherbe ruled out. Full interpretation of the effect of theseand other factors would require longitudinal study.Meanwhile, the present results provide internallyconsistent evidence for interaction between smokingand exposure to fumes as a welder or caulker/burnercausing chronic bronchitis, narrowing of both largeand small lung airways, and breathlessness on exer-tion. The physical nature of the work might itself alsoexert a contributory effect; on the one hand, develop-ing the accessory muscles of respiration and, on theother, in the case ofwork in confined spaces leading toloss of fitness for sustained work with the legs amongmen who did not also engage in active leisure timeactivities.' The association of chronic bronchitis andnarrowing ofall classes ofairways with fume exposurewas consistent with the findings of the other studiescited but the association was stronger than in many ofthem. This could have been due to shipyard welders inconfined spaces having higher fume exposures than

299

copyright. on O

ctober 19, 2020 by guest. Protected by

http://oem.bm

j.com/

Br J Ind M

ed: first published as 10.1136/oem.46.5.292 on 1 M

ay 1989. Dow

nloaded from

300workers in dockyards where semi-confined spaceswould have been more usual, or in factories wherefixed exhaust ventilation was in use. This, however, isspeculative in the absence of reliable measurements ofpersonal fume exposure. The study provided nosupport for the view that occupational bronchitis wasassociated mainly with narrowing of large rather thansmall airways.'Other factors that contributed to the result were the

availability of longitudinal measurements whichprovided evidence on quality control and rigorousexclusion of error due to collinearity from the statis-tical analysis. While the effect of fume exposure wasrelatively large, however, its nature was similar to thatobserved in other studies. The adverse effect of fumeswas mainly confined to smokers and ex-smokers whoformed the great majority of shipyard workers. Alarger number of non-smokers would have beenneeded to explore fully the effects of fumes in thissection of the workforce. On average the effect offumes was similar to that of being a smoker. Whereasamong the welders who smoked, however, the mag-nitude of the effect ofsmoking was independent of thenumber of cigarettes smoked a day, the effect of fumeexposure was related to the average intensity but thegradient was relatively shallow. In the case of bothFEV, and PEF the effect of being in the upper ratherthan the lower 5% of the exposure range wasassociated with an average decrement oflung functionof 1-5 times compared with 0 5 times that of smoking.In addition, the reductions with exposure in FEV%,MEF, and transit times were larger among the oldermen, which suggested that the respiratory impairmentreflected mainly conditions in the past; it could thenhave been due to there having been no exhaustventilation. In the case of FEV, and PEF the inter-action term AE x age was not significant at the 5%level, but with a p value of 0-07 it was not inconsistentwith this hypothesis.

In view of these findings the present results appearto relate mainly to previous conditions in the industry.The effects of present day conditions and informationon welding fumes in non-smokers must await theresult of longitudinal studies on men only exposed tosuch conditions.

This study was made possible by the wholeheartedsupport of the Boilermakers Union and the man-agement and staff of Messrs Austin and Pickersgill,Sunderland. MrT Ayre (personnel servicing manager)supervised the sampling and the shop stewards super-vised the appointments; Dr V J Metcalf and Dr J H RRamsay conducted some clinical interviews; SisterWrought and Nursing Officer Murphy made many ofthe anthropometric measurements; Mrs B Wright andDr I Ashton made the spirometric measurements; DrP

Cotes, Feinmann, Male, Rennie, Wickham

Elmes, Dr A E Cockcroft, and Dr J Lyons read thechest radiographs; Mr R A McNay, regional statis-tician, Northern Regional Health Authority, andDr J Whitehead, department of applied statistics,University of Reading, provided statistical facilitiesand advice. Dr FM El-Gamal, Dr V Woolley, and MrI C Stevenson performed some of the analyses. ELFand CACW received grants respectively from theNorthern Regional Health Authority and SERC(grant number 85141933X), JEC was supported by theMedical Research Council, and VW by Health andSafety Executive. FSR and FMEIG were in receipt ofscholarships respectively from the Royal College ofPhysicians (Prophit) and the Committee of UnitedKingdom Vice-Chancellors and Principals. MessrsP K Morgan donated some equipment. ProfessorP D Oldham, Dr G Berry, and Surgeon-CommanderG H C McMillan kindly commented on an earlyversion of the manuscript.

References

I Newhouse ML, Oakes D, Woolley AJ. Mortality of welders andother craftsmen at a shipyard in NE England. Br J Ind Med1985;42:406-10.

2 Oxhoj H, Bake B, Wedel H, Wilhelmsen L. Effects of electric arcwelding on ventilatory lung. Arch Environ Health 1979;34:211-7.

3 Fogh A, Frist G, Georg J. Respiratory symptoms and pulmonaryfunction in welders. Ann Occup Hyg 1969;12:213-8.

4 Hunnicutt TN Jr, Cracovaner DJ, Myles JT. Spirometricmeasurements in welders. Arch Environ Health 1964;8:661-9.

5 Newhouse ML, Murray R. The present position concerning thebiological effects ofexposure tofume in welders. Abington Hall,Cambridge: Welding Institute, 1979. (Publ 5510/46/79.)

6 McMillan GHG. The health of welders in naval dockyards: therisk of asbestos-related diseases occurring in welders. J OccupMed 1983;25:727-30.

7 Stern RM. Assessment of risk of lung cancer for welders. ArchEnviron Health 1983;38:148-55.

8 McMillan GHG, Pethybridge RJ. The health of welders in navaldockyards: proportional mortality study of welders and twocontrol groups. Journal ofthe Society ofOccupational Medicine1983;33:75-84.

9 Kilburn KH, Warshaw R, Boylen CT. Airway obstruction,volume loss and respiratory symptoms in shipyard welders inLos Angeles: baseline values and cross shift changes. In: SteinRM, Berlin A, Fletcher AC, Jarvisalo J, eds. Health hazards andbiological effects of welding fumes and gases. Amsterdam:Elsevier, 1986:383-6.

10 McMillan GHG, Molyneux MK. The health of welders in navaldockyards: the work situation and sickness absence patterns.Journal ofthe Society ofOccupational Medicine 1981;31:43-60.

11 Akbarkhanzadeh F. Long-term effects of welding fumes uponrespiratory symptoms and pulmonary function. J Occup Med1980;22:337-41.

12 Cotes JE. Lung function: assessment and application in medicine.4th ed. Oxford: Blackwell, 1979.

13 McDermott M, McDermott TJ. Digital incremental techniquesapplied to spirometry. Proceedings of the Royal Society ofMedicine 1977;70:169-71.

14 Chinn DJ, Cotes JE. Transit times analysis of spirograms: whichblow is best? Bull Eur Physiopathol Respir 1986;22:461-6.

copyright. on O

ctober 19, 2020 by guest. Protected by

http://oem.bm

j.com/

Br J Ind M

ed: first published as 10.1136/oem.46.5.292 on 1 M

ay 1989. Dow

nloaded from

Respiratory health ofshipyard welders and caulker/burners15 International Union against Cancer Committee. UICC/Cincin-

nati classification of the radiographic appearances ofpneumoconiosis. A comparative study by the UICC committee.Chest 1970;58:57-67.

16 Musk AW, Cotes JE, Bevan C, Campbell MJ. Relationshipbetween type of simple coalworkers' pneumoconiosis and lungfunction. A nine-year follow-up study of subjects with smallrounded opacities. Br J Ind Med 1981;33:313-20.

17 Medical Research Council. Definition and classification ofchronicbronchitis for clinical and epidemiological purposes. Lancet1965;i:775-9.

18 Fletcher CM. The clinical diagnosis of pulmonary emphysema-an experimental study. Proceedings of the Royal Society ofMedicine 1952;45:577-8.

19 Nie NH, Hull CH, Jenkins JC, Steinbrenner K, Bent DH.Statistical package for the social sciences. 2nd ed. New York:McGraw-Hill, 1975.

20 Dixon WJ. BMDP statistical software. Los Angeles: University ofCalifornia Press, 1981.

21 Darlington RB. Multiple regression in psychological research andpractice. Psychol Bull 1968;69:161-82.

22 Higgins ITT, Cochrane AL. Chronic respiratory disease in arandom sample of men and women in the Rhondda Fach in1958. Br JInd Med 1961;18:93-102.

23 Fletcher C, Peto R, Tinker C, Speizer FE. The natural history ofchronic bronchitis and emphysema. An eight year study of earlychronic obstructive lung disease in working men in London.Oxford: Oxford University Press, 1976.

24 Gilson JC. Occupational bronchitis? Proceedings of the RoyalSociety ofMedicine 1970;63:857-64.

25 Barhad B, Pilat L, Teculescu D. Recent progress in the study ofoccupational lung diseases in Romania. Br J Ind Med1975;32:164-8.

26 Mosinger M, Cherpin J, Rouger P, Luccioni R, Dantin F, DanlinB. Sur les sideroses, sideroscleroses et siderosilicoses. Archivesdes Maladies Professionnelles de Medecine du Travail et deSecurite Sociale 1968;29:59-66.

27 Fawer RF, Gardner AW, Oakes D. Absences attributed torespiratory diseases in welders. Br J nd Med 1982;39:149-52.

28 Cotes JE, Zejda J, King B. Lung function impairment as guide toexercise limitation in work-related lung disorders. Am RevRespir Dis 1988;137:1089-93.

29 Cotes JE, El-Gamal FM. Cardio-respiratory associations withshipyard welding and burning. In: Stern RM, Berlin A, FletcherAC, Jarvisalo J, eds. Health hazards and biological effects ofweldingfumes and gases. Amsterdam: Elsevier, 1986:395-8.

30 Morgan WKC. Industrial bronchitis. Br J Ind Med 1978;35:285-91.

Vancouver style

All manuscripts submitted to the Br J Ind Medshould conform to the uniform requirements formanuscripts submitted to biomedical journals(known as the Vancouver style)The Br J Ind Med, together with many other

international biomedical journals, has agreed toaccept articles prepared in accordance with theVancouver style. The style (described in full inBr Med J, 24 February 1979, p 532) is intended tostandardise requirements for authors.

References should be numbered consecutivelyin the order in which they are first mentioned inthe text by Arabic numerals above the line oneach occasion the reference is cited (Manson'confirmed other reports2-5...). In future refer-ences to papers submitted to the Br J Ind Medshould include: the names of all authors if there

are six or less or, if there are more, the first threefollowed by et al; the title of journal articles orbook chapters; the titles of journals abbreviatedaccording to the style of Index Medicus; and thefirst and final page numbers of the article orchapter.

Examples of common forms of references are:

I International Steering Committee of Medical Editors. Uni-form requirements for manuscripts submitted to biomedicaljournals. Br Med J 1979;1:532-5.

2 Soter NA, Wasserman SI, Austen KF. Cold urticaria: releaseinto the circulation of histamine and eosino-phil chemo-tactic factor of anaphylaxis during cold challenge. N EngIJ Med 1976;294:687-90.

3 Weinstein L, Swartz MN. Pathogenic properties of invadingmicro-organisms. In: Sodeman WA Jr. SodemanWA, eds. Pathologic physiology: mechanismsof disease. Philadelphia: W B Saunders, 1974:457-72.

301

copyright. on O

ctober 19, 2020 by guest. Protected by

http://oem.bm

j.com/

Br J Ind M

ed: first published as 10.1136/oem.46.5.292 on 1 M

ay 1989. Dow

nloaded from