AN INVESTIGATION OF BRAIN-TUMORS AND OTHER MALIGNANCIES IN AN AGRICULTURAL-RESEARCH INSTITUTE

A historical cohort study was carried out in an agricultural research institute in the Republic of Ireland-to investigate a perceived excess of cancer deaths among employees. The objectives of the study were (a ) to confirm whether or not total or cause specific death rates among selected employees were higher than expected based on national figures , and to quantify any excess, and (b) to identify centres and employee grades associated with any excess risk. The cohort comprised all admi nistrative, research, and technical staff employed for at least two ye ars between 1960 and 1980, giving a final total for analysis of 1323 e mployees. Employment history was categorised by place of work and empl oyment grade. Deaths among the cohort were identified and causes of de aths verified. Overall the cohort had a lower than expected mortal- it y compared with national rates (O/E = 0.67). Female deaths were too fe w for analysis but, among the male employees, there was an excess of a ll cancers (O/E = 1.24; 95% confidence interval (95% CI) 0.8-1.9), in particular brain cancer (O/E = 4.69; 95% CI 1.2-11.4) and bladder canc er (O/E = 9.31, 95% CI 1.9-27.2). The pattern of brain tumour deaths w as consistent with an occupational aetiology but it was not possible t o identify specific exposures associated with the excess. All four cas es occurred among research workers in the plant and soil science area. The pattern of bladder cancers was difficult to interpret. The author s are at present participating in a multicentre study to further inves tigate cancer risk in laboratory workers.