International Agency for Research on Cancer (IARC) - Summaries & Evaluations


VOL.: 34 (1984) (p. 37)

5. Summary of Data Reported and Evaluation

5.1 Exposures

Primary aluminium production plants are located in about 40 countries. The two main methods used for aluminium production are Söderberg and prebake, which encompass a number of processes and job categories. Substantial exposures to airborne polynuclear aromatic compounds have been measured in certain occupational settings in this industry. Exposures have been higher in potrooms of plants using the Söderberg process than in those using the prebake process; some workers may have been exposed to both processes. Exposures to fluorides and a variety of other contaminants also occur in potrooms.

5.2 Experimental data

Two incompletely characterized samples of airborne particulate polynuclear organic matter from an aluminium production plant were tested for carcinogenicity by skin application to mice, resulting in a high incidence and early appearance of papillomas and carcinomas of the skin.

Air samples from various locations in two aluminium production facilities were mutagenic to Salmonella typhimurium. No data on cell transformation were available.

5.3 Human data

Asthma, chronic pulmonary disease and skin lesions occur in potroom workers. Fluorosis has occurred in workers in the aluminium production industry.

The lung has been the most common site identified for excess cancer in populations of aluminium production workers. Overall, there was a borderline excess in relative risk, with some studies showing a doubling of risk and some showing no excess. No smoking history was given in any of these studies. In one study in which populations in the industry were compared on the basis of their exposures to pitch volatiles, there was a relationship between incidence of lung cancer and length of exposure, and a significant excess of cancer among workers who had worked for 21 years or more.

In three studies in the same aluminium-producing area, an increased risk of bladder cancer was associated with work in aluminium production in plants where primarily the Söderberg process was used. In one study in which smoking was controlled for, while there was a borderline excess in risk for non-smokers, the risk for smokers was markedly increased.

An excess of lymphosarcoma/reticulosarcoma was noted only in two cohort studies which covered partially the same population.

Statistically significant excess risks of pancreatic cancer and leukaemia were noted as isolated findings in two studies and in one study, respectively.

5.4 Evaluation

The available epidemiological studies provide limited evidence that certain exposures in the aluminium production industry are carcinogenic to humans, giving rise to cancer of the lung and bladder. A possible causative agent is pitch fume. There is inadequate evidence that occupational exposures in the aluminium production industry result in haematolymphopoietic and pancreatic cancer.

There is sufficient evidence that samples of particulate polynuclear organic matter from one aluminium production plant were carcinogenic to experimental animals. However, because of the incomplete characterization of the samples tested, no evaluation of the carcinogenicity to experimental animals of complex mixtures that occur in the aluminium production industry could be made.

A number of individual polynuclear aromatic compounds for which there is sufficient evidence of carcinogenicity in experimental animals have been measured at high levels in air samples taken from certain areas in aluminium production plants.

Taken together, the available evidence indicates that certain exposures in the aluminium production industry are probably carcinogenic to humans.

For definition of the italicized terms, see Preamble Evaluation.

Subsequent evaluation: Suppl. 7 (1987)

Last updated: 20 April 1998

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