Occupational risk factors for nasopharyngeal cancer in Sweden.

Few occupational risk factors have been identified for nasopharyngeal cancer,' although reported associations with poor ventilation,2 smoke, dust, and fumes,3 and exposure to formaldehyde' have suggested that inhalation of carcinogens may play an aetiological part. To provide further leads to occupational risks for this uncommon tumour, we examined on a national basis the association between employment and nasopharyngeal cancer using the Swedish Cancer-Environment Registry (CER).