Leukemia mortality and farming in the prairie provinces of Canada.

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.