Cancer incidence among mild steel and stainless steel welders and other metal workers

Our plain-English summary of Cancer incidence among mild steel and stainless steel welders and other metal workers, by K.S. Hansen, J.M. Lauritsen, A. Skytthe (American Journal of Industrial Medicine, 1996).

The study

• Authors: K.S. Hansen, J.M. Lauritsen, A. Skytthe
• Journal: American Journal of Industrial Medicine
• Published: 1996;30(4):373-82
• Cited by: 57 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The cancer incidence in a historical cohort of 10,059 metal workers employed during the period 1964-1984 was investigated. Standardized incidence ratios (SIR) were calculated based on registry extracts from the Danish Cancer registry. Lifetime exposure data (occupational and other) were obtained by a postal questionnaire in living cohort members and interviews by proxy for deceased and emigrated subjects. The incidence of lung cancer was increased among workers ever "employed as welders" (SIR = 1.38, 95% C.I. 1.03-1.81). There was a significant excess risk of lung cancer among "mild steel (MS) only welders" (SIR = 1.61, 95% C.I. 1.07-2.33) and "nonwelders" (SIR = 1.69, 95% C.I. 1.23-2.26) (indicating carcinogenic exposures other than welding), a borderline significant lung cancer excess among "MS ever welders" (SIR = 1.32, 95% C.I. 0.97-1.76), and a nonsignificant excess risk of lung cancer among "stainless steel (SS) only welders" (SIR = 2.38, 95% C.I. 0.77-5.55). In spite of signs of inconsistency in the risk estimation by duration and latency, we find the results support the conclusions of other studies: employment as a welder is associated with an increased lung cancer risk.

In plain English

This historical cohort study followed 10,059 male Danish metal workers employed at least 12 months between 1964 and 1984 at welding companies. Questionnaires to living members, and interviews with spouses or colleagues of deceased or emigrated members, gave lifetime work histories, including asbestos work and smoking. 8,372 answers were analyzed. Cancers up to the end of 1986 came from the Danish Cancer Registry and were compared with national rates. Lung cancer was higher than expected among men ever employed as welders (SIR 1.38, 95% CI 1.03-1.81), mild steel only welders (SIR 1.61, CI 1.07-2.33) and nonwelding metal workers (SIR 1.69, CI 1.23-2.26). The excess in stainless steel only welders (SIR 2.38, CI 0.77-5.55) was not statistically significant. Two mesotheliomas occurred (SIR 1.25, CI 0.15-4.52). Lung cancer risk showed no clear trend with asbestos exposure, which the authors attributed to few exposed cases and missing information. Risk did not rise clearly with years of welding. The authors concluded that employment as a welder is associated with increased lung cancer risk, and that the nonwelders' excess indicates carcinogenic exposures other than welding.

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: Dynamic historical cohort study of cancer incidence (standardized incidence ratios against national Danish rates)
• Who was studied: 10,059 male metal workers (welders, stainless steel grinders, other metal workers) from 79 Danish companies with stainless steel welding plus five large mild steel welding companies (shipyards excluded). All were employed at least 12 months between 1964 and 1984. Follow-up ran from April 1968 to December 31, 1986. 8,372 respondents contributed 104,698 person-years to the analysis.
• Exposure: Lifetime mild steel welding, stainless steel welding and stainless steel grinding, reported by questionnaire or proxy interview. Subjects were also asked about work with asbestos products, grouped as none, under 10 years, or 10 years or more, and about smoking.
• Main results:
  • Men ever employed as a welder (any type) had increased lung cancer incidence: SIR 1.38, 95% CI 1.03-1.81 (51 observed, 36.84 expected).
  • All respondents ever employed in a welding company: 105 lung cancers observed vs 69.95 expected, SIR 1.51, 95% CI 1.24-1.83.
  • Nonwelding metal workers: lung cancer 45 observed vs 26.68 expected, SIR 1.69, 95% CI 1.23-2.26.
  • Mild steel only welders had a significant lung cancer excess: SIR 1.61, 95% CI 1.07-2.33.
  • Mild steel ever welders had a borderline significant lung cancer excess: SIR 1.32, 95% CI 0.97-1.76.
  • Stainless steel only welders had a nonsignificant lung cancer excess: SIR 2.38, 95% CI 0.77-5.55 (5 cases).
  • Stainless steel grinders had a nonsignificant lung cancer excess: 9 observed vs 6.20 expected, SIR 1.45, CI 0.66-2.75.
  • Stainless steel grinders had a large excess of testicular cancer based on four cases: SIR 5.53, CI 1.51-14.16.
  • Two cases of mesothelioma occurred in the cohort: one in a mild steel welder and one in a nonwelding metal worker.
  • The two mesotheliomas corresponded to an SIR of 1.25 (CI 0.15-4.52).
  • There was no clear trend in lung cancer risk related to asbestos exposure. Among all respondents who reported asbestos exposure, there were 8 lung cancers, SIR 1.38, CI 0.60-2.72.
  • Lung cancer risk did not clearly increase with years of mild steel or stainless steel welding.
  • Welders employed 20 years or more as welders had a low lung cancer risk: 17 observed vs 21.14 expected, SIR 0.80, CI 0.47-1.28.
  • Smoking habits did not differ much between job groups; heavy smokers made up 9.2 to 13.5%.
• The authors' conclusion: The authors concluded that, despite inconsistency by duration and latency, their results support other studies finding that employment as a welder is associated with an increased lung cancer risk. They suggested that mild steel and probably also stainless steel welding are risk factors, and that the excess in nonwelders indicates carcinogenic exposures other than welding.
• Limitations the authors state:
  • Person-years in the long-term exposed groups were few, making estimates by latency and length of employment imprecise.
  • Proxy interviews with spouses and colleagues identified welders with rather low sensitivity. The authors estimated this misclassification could underestimate the relative risk in exposed groups.
  • Company and pension records were incomplete, so cohort ascertainment may have been incorrect.
  • Supervisors' recall of former workers could have introduced selection bias.
  • Long-term welders may be a selected healthy group (healthy worker effect).
  • The asbestos analysis was limited by few exposed cases and missing asbestos information.

Topics

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

Medical terms in this study, explained in our Lexicon: Standardized Incidence Ratio (SIR), Cancer Registry, Lung Cancer, Carcinogenic, Latency.

Related studies

• A historical prospective study of European stainless steel, mild steel, and shipyard welders — L. Simonato, A.C. Fletcher, et al. (1991)
• Risk of lung cancer in workers producing stainless steel and metallic alloys — J.J. Moulin, T. Clavel, et al. (2000)
• Cancer risks among iron and steel workers in Anshan, China, Part I: Proportional mortality ratio analysis — Z. Xu, G.W. Pan, et al. (1996)
• Incidence of cancer among welders, platers, machinists, and pipe fitters in shipyards and machine shops — S. Tola, P.L. Kalliomäki, et al. (1988)
• 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)

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