In a study published in the July 28, 2011 issue of Occupational and Environmental Medicine, New Zealand researchers evaluating 114,000 death records find that people raised on livestock farms as well as adults working in the raising and slaughter of cattle are at significantly higher risk for developing blood cancers such as leukemia.

http://www.sciencedaily.com/releases/2011/07/110727204414.htm
http://health.usnews.com/health-news/family-health/cancer/articles/2011/07/28/growing-up-near-livestock-tied-to-blood-cancers