ASBESTOS, CEMENT, AND CANCER IN THE RIGHT PART OF THE COLON

Objective-The aim was to investigate associations between exposure to mineral fibres and dust, and cancer in subsites within the large bowel . Design-Pooled retrospective cohort studies. Subjects and settings-Bl ue collar workers, employed for at least one year in different trades; asbestos cement or cement workers (n = 2507), other industrial worker s (n = 3965), and fishermen (n = 8092). Main outcome measures-Standard ised incidence ratios (SIRs, national reference rates) were calculated for cause specific cancer morbidity between 1958 and 1989. The observ ation period began 15 years after first employment. Results-The asbest os cement and cement workers had a slightly increased risk of colorect al cancer (SIR 1.5; 95% confidence interval (95% CI) 1.1-2.0). This wa s due to an increase only in the right part of the colon (SIR 2-5; 95% CI 1.6-3.8). The ratio of right (7th revision of the International Cl assification of Diseases ICD-7) 1530-1531)/left (ICD-7 1532-1533) colo n cancer among the asbestos cement and cement workers of 4.8 differed significantly from the ratio both among the other blue collar workers (0.4) and among the fishermen (1.5). As the sensitivity and accuracy w as insufficient, mortality data did not show the excess of cancers in the right part of the colon. Conclusions-An increased incidence of can cer in the right part of the colon was evident in the asbestos cement and cement workers. The distribution of cancers within the colon was n oticeably different from that in other blue collar workers, indicating that our findings cannot be explained by socioeconomic confounding fa ctors. A detailed and appropriate disease classification, based on inc idence data, is necessary in order not to obscure or underestimate eff ects of exposure in epidemiological studies on colorectcal cancer.