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Mortality study of employees with potential exposure to epichlorohydrin: a 10 year update
S P Tsai1, E L Gilstrap, C E Ross
1Corporate Medical Department, Shell Oil Company, Houston, Texas 77252-2463, USA.
Objectives:
A 10 year extension of follow up (up to 1993) of 863 employees who had potential exposure to epichlorohydrin at two chemical plants between May 1948 and December 1965 was conducted to further evaluate the previously reported potential association between exposure to epichlorohydrin and heart disease.
Methods:
The mortality observed was compared with that expected from the death rates from the local male population where these chemical plants are located. Workers were assigned to one of five exposure categories based on their job with the highest level of potential exposure. Vital status was ascertained to the end of 1993.
Results:
Among diseases of particular interest, there were no excess deaths from heart disease (standardised mortality ratio (SMR) 63.3), lung cancer (SMR 63.8), or non-malignant respiratory disease (SMR 37.7) for employees with 20 or more years after first exposure. Based on the level of potential exposure to epichlorohydrin, mortality for heart disease was slightly higher (SMR 75.7, 95% confidence interval (95% CI) 51.8-106.7) in the moderate to heavy exposure group than in the none to light exposure group (SMR 59.5, 95% CI 37.7-89.3); this difference is well within the range of random variation. The SMR for heart disease was 90.4 among employees who had both probable exposure to allyl chloride and moderate to heavy exposure to epichlorohydrin, although it was 88.1 among employees who had moderate to heavy potential exposure to epichlorohydrin but no exposure to allyl chloride.
Conclusions:
This study does not support an association between exposure to epichlorohydrin and heart disease or lung cancer. There were no additional deaths from leukaemia in this update; the raised SMR for leukaemia noted in the previous study has substantially decreased from 500.0 to 161.3 (95% CI 33.2-471.0) and is not significant. The overall mortality and cancer mortality of employees potentially exposed to epichlorohydrin continued to be lower than that of the local population.