Epidemiologic evidence of cancer in aluminum reduction plant workers

Our plain-English summary of Epidemiologic evidence of cancer in aluminum reduction plant workers, by A. Rönneberg, F. Langmark (American Journal of Industrial Medicine, 1992).

The study

• Authors: A. Rönneberg, F. Langmark
• Journal: American Journal of Industrial Medicine
• Published: 1992;22(4):573-90
• Type of article: Review
• Cited by: 34 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This paper reviews the epidemiologic evidence of cancer risks among workers in aluminum reduction plants with emphasis on associations with specific work areas and exposures. Studies of workers manufacturing carbon products outside the aluminum industry were also reviewed since the work environment is similar to that encountered in the carbon area of aluminum plants. We obtained 22 reports from references cited in earlier reviews, through compact disc literature search 1980-1990, and from the Nordic Aluminum Industry's Secretariat for Health, Environment and Safety. Six reports were excluded because the material was included in later studies or because a critical evaluation was impossible. This left 16 publications from 11 separate studies. Work in potrooms with Söderberg electrolytic cells was associated with increased risk of bladder cancer, and the increase was correlated to duration of tar exposure. There was a suggestion of increased risk of leukemias and pancreatic cancers in potroom workers, and of kidney and brain cancers without any clear association with specific exposures or work areas. Singular results showed associations between lung cancer risk and tar exposure in Söderberg plants, and between lung cancer and work in prebake or carbon plants, but interpretation was limited by inadequate data on smoking and asbestos exposure, and by problems connected with the choice of reference populations in these studies.

In plain English

This article was a review, not a new study. The authors looked at published research on cancer among workers in aluminum reduction plants. They also looked at workers in carbon-products plants outside the aluminum industry, because that work resembles the carbon area of aluminum plants. They evaluated 16 publications from 11 separate studies. The main exposure of concern was coal tar pitch volatiles (tars). Some pot lining workers had also been exposed to asbestos. The authors concluded that work in Söderberg potrooms was associated with an increased risk of bladder cancer, and that this risk rose with longer exposure to coal tar pitch volatiles. Two or more studies suggested increased risks of leukemia and pancreatic cancer linked to potroom work, and of kidney and brain tumors not linked to any particular work area. Results for lung cancer were inconsistent. None of the reviewed reports gave any data on asbestos exposure or on asbestos-related diseases such as mesothelioma. The authors said asbestos may have contributed to some of the lung cancer results. They also said that missing smoking data and the choice of comparison populations limited how the lung cancer findings could be interpreted.

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: Review of 16 publications from 11 separate epidemiologic studies (eight of aluminum plant workers, three of carbon plant workers)
• Who was studied: The reviewed studies together included more than 47,000 men from 35 aluminum reduction plants and 4,700 men from nine carbon plants
• Exposure: Mainly tars (coal tar pitch volatiles) and polynuclear aromatic hydrocarbons. Pot lining workers were exposed to tars and fluorides, and to asbestos in plants that used it for pot insulation.
• Main results:
  • Work in Söderberg potrooms was associated with an increased risk of bladder cancer.
  • Three studies showed a relative risk of bladder cancer of 1.5 to 4.5 in tar-exposed workers in Söderberg plants.
  • The reviewed studies did not suggest a bladder cancer risk in carbon plant workers.
  • Two or more separate studies suggested increased risk of leukemia and pancreatic cancer associated with potroom work.
  • Two or more separate studies suggested increased risk of kidney and brain tumors, without any apparent association with a particular work area.
  • Two of the reviewed studies showed statistically significant excesses of lung cancer. Other studies did not, and the lung cancer results were inconsistent.
  • None of the reviewed reports gave any data on asbestos exposure or asbestos-related diseases such as mesothelioma. The authors said such exposure may have contributed to some lung cancer results.
• The authors' conclusion: The authors concluded that the bladder cancer risk in Söderberg potroom work increased with increasing duration of exposure to coal tar pitch volatiles. They also concluded that interpretation of the lung cancer results was limited by the absence of data on smoking and asbestos exposure, and by problems with the choice of reference populations. They called for further study of exposures including asbestos.
• Limitations the authors state:
  • The studies from Norway and Quebec had no smoking data, which made it difficult to draw conclusions about lung cancer.
  • The choice of reference population could change results. In the Norwegian new-plant data, using a national instead of a local reference population would have turned a statistically significant excess of lung cancers into a deficit.
  • Because case numbers were small, increased risks of less common cancers may have gone undetected.
  • Grouping less common cancers, or cancers with different causes, into broad categories may have reduced the information some studies could provide.

Topics

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

Related studies

• Cancer and noncancer mortality among aluminum smelting workers in Badin, North Carolina — E.S. McClure, P. Vasudevan, et al. (2020)
• Irregular opacities in the lung, occupational asthma, and airways dysfunction in aluminum workers — K.H. Kilburn, R.H. Warshaw (1992)
• Cancer incidence among mild steel and stainless steel welders and other metal workers — K.S. Hansen, J.M. Lauritsen, et al. (1996)
• Cancer risks among iron and steel workers in Anshan, China, Part I: Proportional mortality ratio analysis — Z. Xu, G.W. Pan, et al. (1996)
• Asbestos disease in sheet metal workers: proportional mortality update — D. Michaels, S. Zoloth (1988)
• Can lung cancer risk among nickel refinery workers be explained by occupational exposures other than nickel? — T.K. Grimsrud, S.R. Berge, et al. (2005)

Browse more research in American Journal of Industrial Medicine, or return to medical research.