Background: An increased risk of leukemia has been previously noted among farmers.
Purpose: To examine the risk of fatal leukemia according to various farming practices in a large cohort of Canadian farm operators.
Methods: A cohort study of the mortality experience (1971-1987) of male farmers in Manitoba, Saskatchewan and Alberta has been conducted. The census records of 156,242 male farmers identified on the 1971 Census of Agriculture and the corresponding Census of Population were linked to mortality records through 1987.
Results: We observed a statistically significant test for trend (p = 0.03) between leukemia mortality and the number of chickens and/or turkeys owned (relative risk for > or = 130 chickens and/or turkeys = 1.32, 95% CI = 0.99, 1.77). No association was observed between leukemia mortality and either insecticide or herbicide use.
Conclusions: Further research is necessary regarding why farmers exposed to chickens may be at an increased risk of leukemia.