UPDATED AND EXPANDED SWEDISH COHORT STUDY ON TRICHLOROETHYLENE AND CANCER RISK

There is limited evidence for mutagenicity and carcinogenicity of tric hloroethylene (TRI) in experimental test systems. Whether TRI is a hum an carcinogen is unclear, however. This paper presents an update and e xtension of a previously reported cohort of workers exposed to TRI, in total 1670 persons. Among men (n = 1421), the overall standardized mo rtality ratio (SMR) and cancer morbidity ratio (SIR) were close to the expected, with SMR, 0.97; 95% confidence interval (CI), 0.86 to 1.10; and SIR, 0.96; 95% CI, 0.80 to 1.16, respectively. The cancer mortali ty was significantly lower than expected (SMR, 0.65; 95% CI, 0.47 to 0 .89), whereas an increased mortality from circulatory disorders (cardi ovascular, cerebrovascular) was of borderline significance (SMR, 1.17; 95% CI, 1.00 to 1.37). No significant increase of cancer of any speci fic site was observed, except for a doubled incidence of nonmelanocyti c skin cancer without correlation with the exposure categories. In the small female subcohort (n = 249), a nonsignificant increase of cancer and circulatory deaths was observed (SMR, 1.53 and 2.02, respectively ). For both genders, however, excess risks were largely confined to gr oups of workers with lower exposure levels or short duration of exposu re or both. It is concluded that this study provides no evidence that TRI is a human carcinogen, ie, when the exposure is as low as for this study population.