A proportionate cancer morbidity ratio study of workers exposed to chlorinated organic solvents in Taiwan.

We initiated an investigation to examine the possible association between the cancer risk and the chlorinated organic solvents exposure in an electronic factory. To obtain information on the incidence of the various types of cancer among the exposed and comparison groups, the cohort populations were merged with the National Mortality Database, the National Cancer Registry Database, and the National Insurance Hospitalization Database from the Department of Health (DOH), as well as the Labor Insurance Hospitalization Database from the Bureau of Labor Insurance (BLI). The proportionate cancer morbidity ratio (PCMR) was used to estimate the cancer risk of the exposed workers in comparison with either textile workers or electronics workers. After adjustment for age, only the PCMR for breast cancer in the exposed female employees was significantly elevated when compared with the two comparison groups. The increased risk of breast cancer was mainly found in the category of 1989-1997 for year of diagnosis when stratified by calendar year. However, there was no dose-response relationship between female breast cancer risk and duration of employment. Although some PCMRs for the cancers were also increased in the exposed group, female breast cancer was consistently increased when compared with both textile and electronics comparison groups using different exclusion criteria. The results obtained in the present study suggest a possible association between exposure to chlorinated organic solvents and female breast cancer. Since this association has never been reported in the previous studies, further study is needed to clarify the association.