NON-HODGKINS-LYMPHOMA AND AGRICULTURAL PRACTICES IN THE PRAIRIE PROVINCES OF CANADA

Objectives - The aim of this study was to provide an update of a cohor t study (1971-1985) that previously reported a significant trend in th e risk of non-Hodgkin's lymphoma among male Saskatchewan farm operator s according to fuel-oil expenditures and herbicide spraying for farms less than 1000 acres (2570 hectares) by including two additional Canad ian prairie provinces, two additional years of follow-up, and data fro m the 1981 Census of Agriculture. Methods - Information on farmers fro m 1971 records of the Census of Agriculture was linked to 1971 records of the Census of Population, to 1981 records of the Census of Agricul ture, and to death records. Poisson regression was used to estimate ri sks according to herbicide spraying and fuel and oil expenditures. Res ults - The addition of a further two years of follow-up resulted in lo wer risk estimates associated with herbicide spraying for Saskatchewan . No excess risk was observed between herbicide spraying and non-Hodgk in's lymphoma for Alberta or Maintoba in the 1971 data. However, a sig nificantly increased risk of non-Hodgkin's lymphoma according to acres sprayed with herbicides was observed for the three provinces combined when the herbicide spraying data from the 1981 Census of Agriculture was used [greater-than-or-equal-to380 acres (greater-than-or-equal-to 939 hectares) sprayed, rate ratio 2.11, 95% confidence interval 1.1-3. 9]. Conclusions - Although the current results are not entirely consis tent with the original Saskatchewan analysis, they support the overall finding of an association between herbicides and risk of fatal non-Ho dgkins lymphoma. Prospective cohort studies are needed to overcome the limitations of existing epidemiologic studies.