Incidence of lung cancer among shipyard welders investigated for siderosis

Our plain-English summary of Incidence of lung cancer among shipyard welders investigated for siderosis, by T.E. Danielsen, S. Lang rd, A. Andersen (International Journal of Occupational and Environmental Health, 1998).

The study

• Authors: T.E. Danielsen, S. Lang rd, A. Andersen
• Journal: International Journal of Occupational and Environmental Health
• Published: 1998;4(2):85-8
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The incidence of lung cancer among 428 shipyard welders exposed for more than ten years to welding fumes was investigated. The welders were examined for siderosis by the Directorate of Labor Inspection in 1975. The present study was a follow-up based on historical information from the Norwegian registry of dust-exposed workers. Twenty-three welders with siderosis, and 156 welders working at the same shipyards as the siderosis cases were studied as sub-cohorts. There was no loss on follow-up. The observation period was 1976 through 1992. There were 32 cases of cancer from all causes vs 41.3 expected. A nonsignificant excess of lung cancer was observed; 10 cases vs 6.5 expected. The incidence of lung cancer was highest for the welders with more than 30 years since first exposure (7 cases vs 4.1 expected). The sub-cohort of welders with siderosis had no case of lung cancer vs 0.5 expected. These welders were assumed to have experienced high exposure levels for welding fumes. The morbidity of cancer from all causes was low for this small group of blue-collar workers, but the incidence of lung cancer was slightly increased. The increase was not attributable to welders with siderosis. Smoking and asbestos exposure are potential confounders.

In plain English

This Norwegian study followed 428 male shipyard welders who, by 1975, had welded for more than ten years, mostly in confined spaces with poor ventilation. In 1975 they had been examined for siderosis, which the article describes as a generally benign lung condition that may develop after long-term exposure to iron-containing fumes. They had mainly welded mild steel. Asbestos, mainly chrysotile, was used at the shipyards. The authors compared cancers recorded by the Cancer Registry of Norway from 1976 through 1992 among 426 of these welders with the numbers expected for Norwegian men. There were 32 cancers of all types against 41.34 expected. There were 10 lung cancers against 6.47 expected (standardized incidence rate 1.55, 95% confidence interval 0.74 to 2.84), an excess the authors called nonsignificant. No pleural mesothelioma occurred (0.20 expected). The 23 welders with siderosis had no lung cancer (0.48 expected). The authors noted that smoking and asbestos could have contributed, and that smoking data were limited. They also noted that exposure levels were not measured and that the cohort was small. They concluded that the specific effect of welding fumes on lung cancer could not be determined with certainty.

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 study using registry data, comparing observed with expected cancer cases (standardized incidence rates)
• Who was studied: 428 male welders at 15 Norwegian shipyards, all current welders with more than ten years of welding, examined for siderosis in 1975. 426 were followed for cancer from 1976 through 1992 (6,632 person-years). Two sub-cohorts were studied: 23 welders with siderosis, and 156 welders from the same four shipyards as the siderosis cases.
• Exposure: Long-term welding fumes, mainly electric arc welding on mild steel, mostly in confined spaces. Asbestos, mainly chrysotile, was used at the shipyards for insulation in ships and heat protection in ship engines. Quantitative exposure levels were not known.
• Main results:
  • Whole cohort (426 welders), 1976 to 1992: 32 cancers of all types observed vs 41.34 expected (standardized incidence rate 0.77, 95% CI 0.53-1.09).
  • Whole cohort: 10 lung cancers observed vs 6.47 expected (standardized incidence rate 1.55, 95% CI 0.74-2.84), described by the authors as a nonsignificant excess.
  • Whole cohort: no case of pleural mesothelioma (0.20 expected), brain cancer or nasal cancer was observed.
  • Sub-cohort of 23 welders with siderosis: 1 cancer of any type vs 3.16 expected (SIR 0.32). No lung cancer vs 0.48 expected.
  • Sub-cohort of 156 welders from the shipyards with siderosis cases: 13 cancers vs 15.05 expected (SIR 0.86, 95% CI 0.46-1.48). 3 lung cancers vs 2.36 expected (SIR 1.27, 95% CI 0.26-3.71).
  • By time since first exposure, the highest lung cancer SIR was among welders with 40 or more years since first exposure: 3 observed vs 1.55 expected (SIR 1.93, 95% CI 0.40-5.64).
• The authors' conclusion: The authors found a slightly increased incidence of lung cancer, to which asbestos exposure and smoking may have contributed. They concluded that, given the small cohort and potential confounders, the specific effect of welding fumes on lung cancer could not be determined with certainty from this study.
• Limitations the authors state:
  • Only limited information on smoking habits was available.
  • Quantitative exposure levels to welding fumes were not known.
  • Asbestos exposure and tobacco smoking are potential confounders that may have contributed to the lung cancers.
  • Welders who had stopped welding for health reasons before 1975 were not included, which could have produced a healthy-worker selection effect.
  • The observation period was short and the cohort was small, giving considerable statistical uncertainty.

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Asbestos Exposure.

Related studies

• Incidence of cancer among welders and other workers in a Norwegian shipyard — A. Melkild, S. Langård, et al. (1989)
• Incidence of cancer among Norwegian boiler welders — T.E. Danielsen, S. Langård, 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)
• Mortality of welders and other craftsmen at a shipyard in NE England — M.L. Newhouse, D. Oakes, et al. (1985)
• 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)

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