CANCER INCIDENCE IN SWEDISH STERILANT WORKERS EXPOSED TO ETHYLENE-OXIDE

Objectives-To assess the risk of cancer, especially leukaemia, in a co hort of sterilant workers exposed to ethylene oxide (EtO). Methods-A c ohort of 2170 workers employed for at least one year in two plants tha t produce disposable medical equipment sterilised with EtO has previou sly been established. The results of an update with four more years of observation are presented. The cancer incidence was assessed for the periods 1976 to 1990 and 1972 to 1990 and cause specific standardised incidence ratios (SIRs) were calculated. Individual cumulative exposur e to EtO, expressed as ppm-years, was estimated and used in exposure-r esponse analyses. Results-Six lymphohaematopoietic tumours were observ ed (SIR 1.78, 95% confidence interval (95% CI) 0.65-3.88), of which tw o were leukaemias (SIR 2.44; 95% CI 0.30-8.81). When those with cumula tive exposures to EtO below the median value (0.13 ppm-years) were exc luded, and a minimum of 10 years induction latency period was applied, the incidence ratio for leukaemia increased further (SIR 7.14, 95% CI 0.87-25.8), but was still not significantly enhanced. Conclusions-The risk estimate for leukaemia increased, but non-significantly, with ti me since start of exposure, and with cumulative exposures to EtO above the median value. The subjects with leukaemia had, however, only slig htly higher cumulative exposure estimates for EtO than the average coh ort member. Nevertheless, the present results may add some minor evide nce for an association between EtO and an increased risk of leukaemia.