A historical prospective study of European stainless steel, mild steel, and shipyard welders

Our plain-English summary of A historical prospective study of European stainless steel, mild steel, and shipyard welders, by L. Simonato, A.C. Fletcher, A. Andersen, et al (British Journal of Industrial Medicine, 1991).

The study

• Authors: L. Simonato, A.C. Fletcher, A. Andersen, K. Anderson, N. Becker, J. Chang-Claude, G. Ferro, M. Gérin, C.N. Gray, K.S. Hansen
• Journal: British Journal of Industrial Medicine
• Published: 1991;48(3):145-54
• Cited by: 93 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

A multicentre cohort of 11,092 male welders from 135 companies located in nine European countries has been assembled with the aim of investigating the relation of potential cancer risk, lung cancer in particular, with occupational exposure. The observation period and the criteria for inclusion of welders varied from country to country. Follow up was successful for 96.9% of the cohort and observed numbers of deaths (and for some countries incident cancer cases) were compared with expected numbers calculated from national reference rates. Mortality and cancer incidence ratios were analysed by cause category, time since first exposure, duration of employment, and estimated cumulative dose to total fumes, chromium (Cr), Cr VI, and nickel (Ni). Overall a statistically significant excess was reported for mortality from lung cancer (116 observed v 86.81 expected deaths, SMR = 134). When analysed by type of welding an increasing pattern with time since first exposure was present for both mild steel and stainless steel welders, which was more noticeable for the subcohort of predominantly stainless steel welders. No clear relation was apparent between mortality from lung cancer and duration of exposure to or estimated cumulative dose of Ni or Cr. Whereas the patterns of lung cancer mortality in these results suggest that the risk of lung cancer is higher for stainless steel than mild steel welders the different level of risk for these two categories of welding exposure cannot be quantified with precision. The report of five deaths from pleural mesothelioma unrelated to the type of welding draws attention to the risk of exposure to asbestos in welding activities.

In plain English

This multicentre cohort study, pooled at the International Agency for Research on Cancer, followed 11,092 male welders from 135 companies in nine European countries. Observation periods and entry rules varied by country. Deaths were compared with expected numbers from national rates. Overall, 116 lung cancer deaths occurred against 86.81 expected (SMR 134, 95% CI 110 to 160). Lung cancer mortality tended to rise with time since first exposure among mild steel and stainless steel welders. That trend was statistically significant only for predominantly stainless steel welders. No clear relation was found with estimated cumulative doses of total fumes, chromium, hexavalent chromium or nickel. Five deaths from pleural mesothelioma occurred, spread across shipyard, mild steel and stainless steel welders. The authors estimated that fewer than one would be expected. Asbestos exposure could not be measured, and smoking could not be adjusted for. The authors concluded that the data suggest a possible role of stainless steel welding fumes. They also concluded that the mesotheliomas strongly suggest past asbestos exposure affects welders inside and outside shipyards, and that asbestos might have contributed to the lung cancer excess.

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: Historical prospective (historical cohort) mortality and cancer incidence study, pooling national cohorts at IARC and comparing them with national reference rates
• Who was studied: 11,092 male welders (from 12,119 records received) employed in 135 companies in Denmark, England, Finland, France, Germany, Italy, Norway, Scotland and Sweden. Inclusion criteria and observation periods differed by country. 1093 deaths were recorded, and 338 (3.1%) men could not be traced or had emigrated. Cancer incidence was analysed for 7510 welders from the four Nordic countries.
• Exposure: Welding fume. Welders were grouped as shipyard welders, factory mild steel only welders, stainless steel ever welders and a subgroup of predominantly stainless steel welders. Estimated cumulative doses of total fumes, total chromium, hexavalent chromium (Cr VI) and nickel were calculated for men employed at least five years. Shipyard welders were separated because asbestos exposure was judged likely to be higher there. Asbestos exposure itself could not be estimated.
• Main results:
  • Total cohort: lung cancer mortality was in statistically significant excess, with 116 observed versus 86.81 expected deaths (SMR 134, 95% CI 110 to 160).
  • Total cohort: all-cause mortality was below that of the general population (1093 observed versus 1179.08 expected, SMR 93). The authors attributed this deficit almost entirely to the low mortality of stainless steel welders.
  • Total cohort: other cancers in excess were bladder, kidney and larynx cancer and lymphosarcoma. Bladder cancer (15 observed versus 7.86 expected, SMR 191, 95% CI 107 to 315) was described as statistically significant.
  • Lung cancer SMR tended to increase with time since first exposure among mild steel, stainless steel ever and predominantly stainless steel welders. The trend was statistically significant only for predominantly stainless steel welders (chi-square 5.03, 1 degree of freedom, p less than 0.05).
  • Mild steel welders and predominantly stainless steel welders: lung cancer mortality 20 or more years after first exposure was approximately doubled. The excess was not related to duration of employment or to cumulative exposure to total fumes, total chromium, Cr VI or nickel.
  • Stainless steel ever welders with at least five years of employment, 20 or more years after first exposure: the lung cancer SMR was 170 in the high Cr VI category versus 123 in the low category. The difference was not significant.
  • Total cohort: five deaths from pleural mesothelioma were identified, three of them at least 20 years after first exposure. These deaths occurred among shipyard, mild steel and stainless steel welders. Expected numbers were not formally computed, but the authors estimated fewer than one expected death. One further death after the end of follow up was not included.
  • Nordic welders (incidence analysis): the lung cancer excess was confirmed (92 observed versus 67.02 expected, SIR 137, 95% CI 111 to 168). Prostate cancer incidence was also raised (SIR 146, 95% CI 102 to 202). Neither cancer showed an association with exposure.
  • Total cohort: there was no excess of non-malignant respiratory disease. Respiratory system deaths were 42 observed versus 60.84 expected (SMR 69).
• The authors' conclusion: The authors concluded that the data suggest a possible role of stainless steel welding fumes in the lung cancer excess, though they could not quantify with precision the different risk for stainless versus mild steel welders. They concluded that the five mesotheliomas strongly suggest past asbestos exposure affects welders inside and outside shipyards, and that asbestos might have contributed to the excess lung cancer. In their view, smoking could have contributed but was unlikely to explain the excess.
• Limitations the authors state:
  • Smoking information was not available for the whole cohort, so no adjustment for tobacco was possible.
  • The role of asbestos in the lung cancer excess could not be evaluated because company information on asbestos exposure was too poor.
  • Cumulative doses for part of the cohort were based on company information rather than individual histories, which likely introduced misclassification.
  • There was no systematic information on previous jobs, so confounding by earlier occupational carcinogen exposure, including asbestos, cannot be ruled out.
  • Inclusion criteria differed from country to country, and the cohort was heterogeneous in exposure.

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Occupational Exposure, Cumulative Exposure, Pleural 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)
• Lung cancer in mild steel welders — K. Steenland, J. Beaumont, et al. (1991)
• Exposure to stainless steel welding fumes and lung cancer: a meta-analysis — B. Sjögren, K.S. Hansen, et al. (1994)
• Nickel-related cancer in welders — S. Langård (1994)
• Incidence of cancer among welders, platers, machinists, and pipe fitters in shipyards and machine shops — S. Tola, P.L. Kalliomäki, et al. (1988)
• Incidence of cancer among Norwegian boiler welders — T.E. Danielsen, S. Langård, et al. (1996)

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