Lung cancer in mild steel welders

Our plain-English summary of Lung cancer in mild steel welders, by K. Steenland, J. Beaumont, L. Elliot (American Journal of Epidemiology, 1991).

The study

• Authors: K. Steenland, J. Beaumont, L. Elliot
• Journal: American Journal of Epidemiology
• Published: 1991;133(3):220-9
• Cited by: 36 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

To investigate lung cancer risk, the authors conducted a historical cohort mortality study of 4,459 mild steel welders who had been employed at three midwestern plants which manufactured heavy equipment. Follow-up began in the mid-1950s and extended through 1988. All welders had at least 2 years welding experience (average duration, 8.5 years). This cohort had no occupational exposure to asbestos or stainless steel fumes (containing nickel and chromium), two potential confounders in previous welders studies. A comparison population of 4,286 nonwelders, all with at least 2 years employment at the same plants, was also studied. Nonwelders had never been welders and were allowed to have no more than 90 days employment as a painter, foundryman, or machinist. Sampling data collected from 1974-1987 indicated that welders were exposed to 6-7 mg/m3 of total particulate and 3-4 mg/m3 of iron oxide, while nonwelders had negligible exposures to welding fumes. When compared with the United States population, both welders and nonwelders had elevated rates for lung cancer (standardized mortality ratios (SMRs): welders, SMR = 1.07; nonwelders, SMR = 1.17), but neither SMR was significantly elevated. Limited smoking data based on a 1985 survey indicated that both welders and nonwelders smoked more than the United States population, possibly accounting for part of their elevated lung cancer rates. There was no trend of increased risk for welders with increased duration of exposure. The only other cause of death significantly elevated was emphysema among welders. Nonmalignant respiratory disease was not elevated for welders (SMR = 0.96). When welders were compared with nonwelders directly for lung cancer, the rate ratio was 0.90.

In plain English

This historical cohort mortality study followed men at three Illinois heavy equipment plants from the 1950s through 1988. It included 4,459 men with at least 2 years as mild steel welders or welder helpers, and 4,286 nonwelders from the same plants. The authors judged welders' asbestos exposure at the plants to be of little consequence, though past use of asbestos-coated rods could not be ruled out. Sampling from 1974-1987 found welders exposed to about 6-7 mg/m3 of total particulate and 3-4 mg/m3 of iron oxide. Compared with US rates, lung cancer deaths were somewhat higher, but not significantly, for welders (SMR 1.07, 95% CI 0.76-1.46) and nonwelders (SMR 1.17, 95% CI 0.92-1.47). Compared directly with nonwelders, welders' lung cancer rate ratio was 0.90 (95% CI 0.60-1.36), with no trend by years of welding. Emphysema deaths were significantly elevated among welders. One welder died of mesothelioma. The authors concluded that their data suggest these mild steel welders did not have an excess lung cancer risk due to their occupation. They noted limited smoking data and limited power in some subgroups.

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 cohort mortality study comparing welders with the US population and directly with nonwelders at the same plants
• Who was studied: 4,459 hourly male workers with at least 2 years as production (arc) welders or welder helpers (welder cleaners), and 4,286 hourly male nonwelders with at least 2 years of employment, at three heavy equipment plants in Illinois owned by one company. Follow-up ran from the mid-1950s through 1988. Welder helpers were included because they worked next to welders and breathed many of the same fumes.
• Exposure: Mild steel arc welding fumes, with no stainless steel fumes. Sampling from 1974-1987 showed welders exposed to 6-7 mg/m3 of total particulate and 3-4 mg/m3 of iron oxide, while nonwelders had negligible exposure. Some past welding rods were coated with asbestos and their use at these plants could not be ruled out. The authors judged the welders' past asbestos exposure at the plants to be of little consequence.
• Main results:
  • Compared with the US population, lung cancer mortality was SMR 1.07 (95% CI 0.76-1.46; 39 deaths) for welders and SMR 1.17 (95% CI 0.92-1.47; 74 deaths) for nonwelders. Neither was statistically significant.
  • In the direct comparison with nonwelders as the reference group, welders' overall lung cancer rate ratio was 0.90 (95% CI 0.60-1.36)
  • Among welders there was no trend of increasing lung cancer risk with longer duration of welding exposure
  • Emphysema was the only other cause of death significantly elevated among welders (SMR 2.36, 95% CI 1.07-4.48; 9 deaths). Nonmalignant respiratory disease overall was not elevated for welders (SMR 0.96).
  • One death from mesothelioma occurred in the welder cohort
  • In 1985 survey data, about 22 percent of the cohort had never smoked, compared with 30 percent of the US population of the same age. Ever-smoking was about the same in welders (78 percent) and nonwelders (79 percent).
• The authors' conclusion: The authors concluded that their data suggest the mild steel welders in this cohort did not have an excess lung cancer risk due to their specific occupation
• Limitations the authors state:
  • Some lung cancer excess was seen against the US population, statistical power was limited in some subgroups, and smoking data were limited
  • There were no data on the amount smoked
  • No exposure measurements existed for the earlier stick-welding period
  • Past use of asbestos-coated welding rods at the plants could not be ruled out
  • Duration of welding may not reflect cumulative dose, because highly exposed welders may have moved to nonwelding jobs

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Occupational Exposure, standardized mortality ratio (SMR), Emphysema, rate ratio.

Related studies

• Cancer incidence among mild steel and stainless steel welders and other metal workers — K.S. Hansen, J.M. Lauritsen, et al. (1996)
• 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)
• The health of welders in naval dockyards. The risk of asbestos-related diseases occurring in welders — G.H. McMillan (1983)
• Exposure to stainless steel welding fumes and lung cancer: a meta-analysis — B. Sjögren, K.S. Hansen, et al. (1994)
• Mortality of welders and other craftsmen at a shipyard in NE England — M.L. Newhouse, D. Oakes, et al. (1985)

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