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


VOL.: 34 (1984) (p. 101)

5. Summary of Data Reported and Evaluation

5.1 Exposures

The vast majority of coke is produced in by-product (slot) coke ovens. Substantial airborne exposures to polynuclear aromatic hydrocarbons have been measured in occupations in the production of coke. The highest exposures have been reported for workers on the topside of the coke-oven battery. The presence of other substances (including aromatic heteronuclear and substituted aromatic compounds) in the workplace air has been reported.

5.2 Experimental data

A sample from a coke-oven main was tested for carcinogenicity in mice by topical application and produced skin carcinomas. Samples obtained either from the topside or main of a coke oven showed initiating activity in a mouse-skin two-stage model. Samples of tar from coke ovens were also tested by inhalation in mice and rats, producing benign and malignant tumours of the lung; in one of these inhalation studies in mice, skin tumours were produced.

A sample from the topside of a coke oven was mutagenic to Salmonella typhimurium and in several mammalian cell systems (L5178Y mouse lymphoma, Chinese hamster ovary and BALB/c 3T3); it also induced DNA damage in Syrian hamster embryo cells and induced sister chromatid exchange in Chinese hamster ovary cells. The sample caused morphological transformation in BALB/c 3T3 cells and enhanced viral transformation of Syrian hamster embryo cells. A coke-oven sample taken from the gas-collector main was also mutagenic to Salmonella typhimurium and in mammalian cells (L5178Y mouse lymphoma) and induced sister chromatid exchange (in Chinese hamster ovary cells).

5.3 Human data

Chronic bronchitis occurs among coke-production workers, particularly in those who smoke.

Case reports of tumours of the skin (including the scrotum), bladder and respiratory tract in association with employment in industries involving the destructive distillation of coal suggested a link between that industry and human cancer. Despite their methodological shortcomings, the descriptive epidemiological studies based on death certificates corroborated these early suggestions.

The site at which excess cancer rates have been identified most commonly among workers in coke production is the lung. All but two of the relevant analytical epidemiological cohort studies provide evidence that work in coke production carries a significantly elevated risk of lung cancer. The two studies showing no excess suffered from serious methodological limitations. The risk for workers in the coke-oven area varied from three- to seven-fold, the highest risk being for men employed for five years or more and working fulltime on the topside of the coke oven. Few of the studies corrected for smoking.

Excess risk for kidney cancer has been associated with work in coke plants. In one study, a seven-fold increase in risk was seen for all workers employed for five years or more at coke ovens.

In single studies, excess risks were reported for cancers of the large intestine and pancreas.

5.4 Evaluation

There is sufficient evidence from observations made in the first half of this century that occupational exposures to the products of the destructive distillation of coal give rise to skin cancer in humans.

The available epidemiological studies provide sufficient evidence that certain exposures in the coke-production industry are carcinogenic to humans, giving rise to lung cancer. A possible causative agent is coal-tar fume. There is limited evidence that such occupational exposures produce cancer of the kidney, and inadequate evidence that they result in intestinal and pancreatic cancers.

There is sufficient evidence that samples of tars taken from coke ovens are carcinogenic to experimental animals, producing lung and skin tumours.

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 coke production plants.

The available evidence indicates that certain exposures in the coke production industry are 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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