Nasal cancer among North American woodworkers: another look.

A death certificate case-control study of sinonasal cancer in Ontario has found increased relative risks among wood-workers. The results from four North American studies have been combined using the Mantel-Haenszel method, and the relative risk for woodworkers has been found to be 1.6 (P less than .01). It is concluded that North American softwoods, as well as hardwoods, may contain carcinogenic substances or their precursors.