A study to investigate the associations between head and neck cancer (HNC) risk and occupations.  
HNC includes cancers originating in the oral cavity, the oropharynx, the hypopharynx, and the larynx.
Several occupational exposures are recognized risk factors for some HNC sites (asbestos and strong acids for larynx; leather dust, and wood dust for sinonasal cancer) and suspected to be risk factors for other cancers of the head and neck.