Incidence of cancer among welders, platers, machinists, and pipe fitters in shipyards and machine shops

Our plain-English summary of Incidence of cancer among welders, platers, machinists, and pipe fitters in shipyards and machine shops, by S. Tola, P.L. Kalliomäki, E. Pukkala, et al (British Journal of Industrial Medicine, 1988).

The study

• Authors: S. Tola, P.L. Kalliomäki, E. Pukkala, S. Asp, M.L. Korkala
• Journal: British Journal of Industrial Medicine
• Published: 1988;45(4):209-18
• Cited by: 52 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000284).

Abstract

The incidence of cancer in 12,693 shipyard and machine shop male workers (1689 welders, 4308 platers, 6003 machinists, 693 pipe fitters) employed for at least one year between 1945 and 1960 was investigated in a retrospective cohort study. The welders had welded only mild steel and had not been exposed to hexavalent chromium containing fume. The follow up was 99.7% complete and the total number of person-years was 304,682. The incidence of cancer in 1953-81 was ascertained through the Finnish Cancer Registry. The observed numbers of cases of cancer were compared with the expected numbers based on regional urban rates. The smoking habits of the cohort were surveyed with a postal questionnaire sent to a sample of 961 workers. The smoking habits of the cohorts were similar and smoking was not more common than among the general population. The total number of cases of cancer was 611 (exp 629) among the shipyard workers and 376 (exp 388) among the machine shop workers. The incidence of lung cancer was increased among the shipyard workers (obs 227, exp 192). This excess was observed in all the worker groups and was most evident for the pipe fitters and platers. Among the machine shop workers, the incidence of lung cancer was lower than expected with the exception of the welders who had a slightly raised risk of lung cancer (obs 14, exp 10). The incidence of laryngeal cancer was slightly raised among the shipyard workers (obs 24, exp 20) but not in the machine shop workers. No excess risk was observed among the welders. The incidence of cancer of the prostate was increased among the machine shop workers (obs 39, exp 31) but not in the shipyard workers. The excess was statistically significant for the welders. No pronounced excess could be found for other types of cancer. Analysis by the duration or exposure showed that the excess of lung cancer in the shipyard workers was most evident during the last period of observation (1972-81). No other trends were obvious and the slight excess of lung cancer observed among the welders did not increase with increasing follow up time. No excess risk for mesothelioma was found. The small excess of lung cancer in welders could be due to chance. The fact that only a small and statistically insignificant excess of lung cancer could be found among this group of heavily exposed welders suggest that if the risk of lung cancer was associated with welding this risk must nowadays be low and probably too low to be unequivocally detected in most epidemiological studies.

In plain English

This retrospective cohort study from Finland followed 12 693 men who had worked for at least one year between 1945 and 1960 as welders, platers, machinists or pipe fitters in five shipyards and four machine shops. Cancer cases from 1953 to 1981 were identified through the Finnish Cancer Registry and compared with the numbers expected from regional urban rates. The article states that asbestos was used for insulation in the shipyards from about 1955 to the middle of 1970, but no asbestos measurements were available. Pipe fitters were considered the group most exposed to asbestos. Overall cancer was not raised. Shipyard workers had more lung cancer than expected (227 observed, 192.1 expected; standardised incidence ratio 118, 95% confidence limits 103 to 135). The highest ratio was in shipyard pipe fitters (23 observed, 15.0 expected). Small lung cancer excesses among welders were not statistically significant. No excess risk of mesothelioma was found. Smoking habits were similar across the groups. The authors concluded that the shipyard lung cancer excess was most probably explained by asbestos exposure, although this was difficult to confirm. They concluded that the welders' small excess may be due to chance.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective cohort study comparing observed cancer cases with expected numbers from regional urban rates (standardised incidence ratios), with a postal smoking questionnaire sent to a sample of workers
• Who was studied: 12 693 male workers (1689 welders, 4308 platers, 6003 machinists, 693 pipe fitters) who worked continuously for at least one year between 1945 and 1960. There were 7775 in five shipyards and 4918 in four machine shops in south-southwestern Finland. Cancer incidence was followed from 1953 to 31 December 1981, totalling 304 682 person-years.
• Exposure: Manual metal arc mild steel welding fumes, and asbestos used as insulation in the shipyards from about 1955 to the middle of 1970 (fiber type not stated). Spraying of asbestos was common, but no measurements of asbestos fibres were available. Pipe fitters were judged to have the highest asbestos exposure. Asbestos use in the machine shops was described as minor and not sprayed.
• Main results:
  • Total cancers: 611 observed against 629.4 expected among shipyard workers (SIR 97, 95% CL 90-105). Among machine shop workers, 376 observed against 388.3 expected (SIR 97, 95% CL 87-107).
  • Lung cancer (excluding mesothelioma) among all shipyard workers: 227 observed against 192.1 expected (SIR 118, 95% CL 103-135). The excess was seen in all shipyard worker groups.
  • Shipyard pipe fitters, considered the most asbestos-exposed group, had the highest lung cancer ratio: 23 observed against 15.0 expected (SIR 153, 95% CL 97-230).
  • Lung cancer among welders was not statistically significantly raised. Shipyard welders had 27 observed against 23.5 expected (SIR 115, 95% CL 76-167). Machine shop welders had 14 observed against 10.4 expected (SIR 135, 95% CL 74-226). Machine shop workers overall had 110 observed against 118.8 expected (SIR 93).
  • No excess risk of mesothelioma was found in the cohort.
  • Laryngeal cancer among shipyard platers was raised (14 observed, 9.2 expected, SIR 152, 95% CL 83-255). The authors said this may possibly be explained by asbestos exposure.
  • Prostate cancer among machine shop welders was statistically significantly raised: 7 observed against 2.5 expected (SIR 280, 95% CL 113-557). The authors found no explanation in terms of exposure.
  • Smoking habits of shipyard and machine shop workers were similar, and roughly matched average Finnish smoking habits.
• The authors' conclusion: The authors concluded that most of the relatively small increase in lung cancer among some groups of shipyard workers may possibly be explained by asbestos exposure, although this was difficult to confirm. They concluded that the small lung cancer excess among welders is difficult to interpret and may be due to chance.
• Limitations the authors state:
  • No environmental or occupational hygiene measurements of asbestos fibres were available for the shipyard areas.
  • Exposure assessment was mainly qualitative, based on documents and interviews.
  • The healthy worker effect could not be eliminated, and no reliable estimate of its impact was available.
  • Prostate cancer varies geographically in Finland and is highest in the study areas, so the authors said the prostate finding should be interpreted with caution.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Welders.

Medical terms in this study, explained in our Lexicon: Cohort Study, Cancer Registry, Habit, Lung Cancer, Laryngeal Cancer, Mesothelioma.

Related studies

• Cancer incidence among mild steel and stainless steel welders and other metal workers — K.S. Hansen, J.M. Lauritsen, et al. (1996)
• Incidence of lung cancer among shipyard welders investigated for siderosis — T.E. Danielsen, S. Lang rd, et al. (1998)
• A historical prospective study of European stainless steel, mild steel, and shipyard welders — L. Simonato, A.C. Fletcher, et al. (1991)
• Incidence of cancer among Norwegian boiler welders — T.E. Danielsen, S. Langård, et al. (1996)
• Mortality of welders and other craftsmen at a shipyard in NE England — M.L. Newhouse, D. Oakes, et al. (1985)
• Incidence of cancer among welders and other workers in a Norwegian shipyard — A. Melkild, S. Langård, et al. (1989)

Browse more research in British Journal of Industrial Medicine, or return to medical research.