A survey of occupational cancer in the rubber and cablemaking industries: results of five-year analysis, 1967-71.

140-151. A mortality study of 40 867 subjects employed in the rubber and cablemaking industries on 1 February 1967 is reported. No evidence is found of a continued excess risk of neoplasms of the bladder in people who entered the industry after 1949. For those employed before that date, during the period when known bladder carcinogens were in use, the SMR is higher than predicted, indicating that men are still dying with occupationally induced tumours. An excess of all neoplasms was noted in the five years of the study. In certain sections of the industry (tyre manufacture, belting hose rubber with asbestos, and flooring industry) there is a particular excess of bronchial carcinoma. In those sections which use asbestos such an excess is not altogether surprising, but this does not apply to the tyre industry. The latter industry is sufficiently large (16 035 men in the study compared with 4 350 in the belting, hose rubber with asbestos, and flooring industry) for attention to be focused on particular operations. Two job groups are found to share the excess: moulding, press, autoclave, and pan curemen; and finished goods, packaging, and despatch. Job selection may play a part in the latter, as the work is generally considered suitable for older and perhaps less healthy people. Crude analyses have been undertaken to indicate whether the excesses are due to regional differences or to the population comprising an abnormally high proportion of smokers. No excesses are found in other smoking-related diseases. Although the effects of differences in smoking habit and regional differences cannot be ruled out, the indications are against these factors being the primary cause. The difficulties of this type of study are discussed. It is emphasized that the results can be used only as an indication of a problem area and the type of further study required. A more exact study would concentrate on five-year cohorts of people who left the industry between 1940 and 1960. A study of five-year cohorts of people who entered the industry in the same period would also be valuable. An attempt has been made to perform the latter, but it would be hazardous to draw too many conclusions from this because the population comprises those who `survive' in the industry until 1967.