Incidence of cancer among workers producing calcium carbide

Our plain-English summary of Incidence of cancer among workers producing calcium carbide, by H. Kjuus, A. Andersen, S. Langård (British Journal of Industrial Medicine, 1986).

The study

• Authors: H. Kjuus, A. Andersen, S. Langård
• Journal: British Journal of Industrial Medicine
• Published: 1986;43(4):237-42
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The overall mortality and the incidence of cancer have been studied among male employees at a plant producing calcium carbide. The cohort was defined as all men employed at the plant for at least 18 months in the period 1953 to 1970 and was classified according to 10 occupational categories. The 790 men have been observed from 1953 to 1983 and the incidence of cancer in the cohort has been compared with national incidence rates. A significant excess of colonic cancer (standardised incidence ratio, SIR = 2.09) and of prostatic cancer (SIR = 1.78) was found, and also a slight excess of lung cancer among furnace and maintenance workers (SIR = 1.56). The possible exposure of the workers to polycyclic aromatic hydrocarbons, asbestos, and cadmium is discussed.

In plain English

This study followed 790 men who worked at least 18 months, and before 1 January 1970, at Norway's only calcium carbide plant, in Odda. Cancers from 1953 to 1982 were found through Norway's Cancer Registry and compared with national male rates. Possible exposures included dust, heat, occasional polycyclic aromatic hydrocarbons (PAH), and asbestos insulation around the furnaces. The fiber type was not stated. PAH was never measured, and earlier asbestos amounts were unknown. Deaths were slightly below expected (SMR 0.93). The men had 92 cancers against 76.8 expected (SIR 1.20, confidence interval 0.98 to 1.48). Colon cancer (12 cases, SIR 2.09) and prostate cancer (25 cases, SIR 1.78) were significantly raised. Lung cancer was not significantly raised overall (10 cases, SIR 1.15). Furnace and maintenance workers had 6 lung cancers against 3.85 expected. The authors were reluctant to suggest asbestos caused the colon cancer excess, since lung cancer was not clearly raised. Past smoking histories were unavailable; a 1977 survey found 59% of 458 employees smoked daily versus 44% of Norwegian men, so the authors could not rule out slight confounding by smoking.

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 plant-based cohort study of cancer incidence and overall mortality, compared with national male rates
• Who was studied: 790 men employed for at least 18 months and before 1 January 1970 at the only calcium carbide plant in Norway (Odda), followed from 1 January 1953 to the end of 1982; 18 779 person-years
• Exposure: Work in calcium carbide production (heat, calcium carbide, quicklime, anthracite dust, carbon monoxide, acetylene). Intermittent PAH exposure in some tasks, with no PAH measurements. Asbestos (fiber type not stated) used as insulation around the furnaces; amounts in earlier years unknown, about 1000 kg a year in 1978-82. Ten occupational categories.
• Main results:
  • Whole cohort: 234 deaths observed versus 250.65 expected, SMR 0.93 (95% CI 0.81-1.06)
  • Whole cohort: 92 cancer cases observed versus 76.8 expected, SIR 1.20 (95% CI 0.98-1.48)
  • Whole cohort: statistically significant excess of colon cancer (12 observed, 5.73 expected, SIR 2.09, 95% CI 1.08-3.66) and prostate cancer (25 observed, 14.01 expected, SIR 1.78, 95% CI 1.16-2.63)
  • Whole cohort: lung cancer 10 observed versus 8.71 expected, SIR 1.15 (95% CI 0.55-2.11), not significant
  • Furnace and maintenance workers combined: 6 lung cancer cases versus 3.85 expected (SIR 1.56), the highest SIR among the occupational groups
  • Whole cohort: stomach cancer 5 observed versus 10.28 expected, SIR 0.49, deficit not statistically significant
  • By duration of employment: 6 of the 10 lung cancers occurred in men employed more than 25 years, but no dose-response relation was seen
  • Cyanamide/dicyandiamide production workers: no excess of cancer
  • Using county rural rates instead of national rates, the colon cancer SIR fell from 2.09 to 1.80 and remained significant
• The authors' conclusion: The authors were reluctant to suggest asbestos as a possible cause of the colon cancer excess, since no definite lung cancer excess was seen. They stated that a possible occupational contribution to the prostate cancer excess should be considered, and that chance findings (type 1 errors) might explain several of the associations.
• Limitations the authors state:
  • Men who left employment before 1953 were not eligible. This loss may be related to health, so healthy worker effects may be operating.
  • No past smoking information was available for the whole cohort. In a 1977 survey of 458 employees, 59% smoked daily versus 44% of Norwegian men, so the authors could not rule out slight confounding by smoking.
  • Numbers for the selected cancer sites were too small to evaluate trends by employment period
  • Some associations may be chance findings (type 1 errors)

Topics

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

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