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

IRON AND STEEL FOUNDING

VOL.: 34 (1984) (p. 133)

5. Summary of Data Reported and Evaluation

5.1 Exposures

The iron and steel foundry industry employs approximately two million workers. This industry is diverse in terms of materials and processes, resulting in occupational exposures to a variety of substances. Substantial exposures to silica and carbon monoxide continue to occur in many foundries. Occupational exposures to airborne polynuclear aromatic compounds have also been found, resulting mainly from the thermal decomposition of carbonaceous ingredients commonly added to foundry sand. In addition, some steel foundry workers (e.g., fettlers) are exposed to airborne chromium and nickel compounds. The introduction of new organic binder materials (beginning in the late 1950s) has resulted in new exposures of foundry workers to chemicals, including phenol, formaldehyde, isocyanates and various amines.

5.2 Experimental data

No data on the carcinogenicity to experimental animals of complex mixtures found in the iron and steel founding industry were available.

Numerous samples taken from the air in various locations in two iron and one steel foundries were mutagenic to Salmonella typhimurium. No data on cell transformation were available.

5.3 Human data

Chronic respiratory effects such as silicosis, other pneumoconioses and chronic bronchitis occur among foundry workers. Occupational asthma and dermatitis have also been described following the introduction of new chemical binders.

Data derived from reports of mortality statistics in the USA and the UK indicate excess mortality from lung cancer for 'foundry workers', but the definition of this occupational category included many occupational groups. Cancers of the digestive tract sometimes occurred in higher ratios than in the total population.

Analytical cohort epidemiological studies of foundry workers were carried out in a number of countries. Elevated risks of lung cancer (between about 1.5- and 2.5-fold), some of which were statistically significant, were observed in foundry workers when compared to the general population. In two study populations, comparison with other steel workers did not consistently reveal an elevated rate.

The proportion of lung cancers among all deaths was evaluated in some studies, and found to be about 1.5- to 1.8-fold higher than this proportion in the general population; however, there are difficulties associated with the interpretation of proportionate mortality ratios.

None of the cohort studies explicitly controlled for the potentially confounding smoking habits of foundry workers, although in some studies in which questionnaire data were used, the smoking habits of current workers were not significantly different from those of the general population. Other potential biases in these studies could have arisen from the imprecise classification of jobs.

An association between foundry work and lung cancer was observed in one case-control study.

In two studies, in which site-specific cancer deaths among iron and steel-foundry workers were compared with the corresponding rates for the general population, significantly increased risks for cancer of the digestive system were observed: in one, the elevated risk was in the 'digestive system', in the other, it was in 'stomach cancer'.

Results from studies of a single cohort of steel-foundry workers in the USA showed a significantly elevated risk of 'cancer of the genito-urinary system' when compared with the entire steel-worker population under study, the risk being significantly elevated also for some specific sites (prostate and kidney).

5.4 Evaluation

The available epidemiological studies provide limited evidence that certain exposures in iron and steel founding are carcinogenic to humans, giving rise to lung cancer. There is inadequate evidence that such exposures result in cancers of the digestive system and genito-urinary system.

A number of individual compounds for which there is sufficient evidence of carcinogenicity have been measured at high levels in air samples taken from certain areas in iron and steel foundries.

Taken together, the available evidence indicates that occupational exposures occur in iron and steel founding which 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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