Epidemiological and clinical investigations among employees in a former herbicide production process

Objectives To evaluate cancer incidence among employees assigned to a benzothiadiazin herbicide production facility between 1974 and 1984. Methods Retrospective cohort study including 185 employees who had worked at least 3 months in the facility. Cancers were identified by review of occupational medical records and interview. Standardized incidence ratios (SIRs) were computed using comparison data provided by the Saarland Cancer Registry. Separately, a medical examination including sonography of the prostate and thyroid and PSA testing was offered to all cohort members including retirees. Results Between 1975 and 2002, 12 cancers were observed compared with 10.3 expected cases (SIR 1.2; 95% confidence interval 0.6-2.0). Cancer types (including two prostate, two colon and one rectal cancer) were distributed unremarkably with no clustering of rare cancers. Medical screening and subsequent specialist referrals led to detection of three prostate cancers among 117 participants in the screening examination. Conclusions Because of the limited study power, a link between former employment in this herbicide production process and the occurrence of cancer cannot be ruled out with confidence, although the observed incidence and distribution of cancers in this small cohort may be consistent with that expected in the general population. Detection of three prostate cancers via the examination program is also consistent with the experience of cancer screening programs that include PSA testing. Enhanced screening for prostate cancer among men over age 50 can lead to detection of cancers at earlier ages than would otherwise be the case. This likelihood needs to be planned for and addressed in communications with the study population prior to undertaking such initiatives.