Occupational exposure and head and neck carcinoma. An epidemiological case-control study was conducted to investigate occupational risk factors in cancers of the upper respiratory and digestive tract. Cases were men with squamous cell carcinoma of the oropharynx (667), hypopharynx (348), glottis (246), supraglottis (219), epilarynx (204), and 4 subsites of the oral cavity (787). Controls were healthy patients or patients with cancer of another site or another histological type (147 men). Past occupational exposures of cases and controls were compared. The analysis was performed independently for each site of cancer, controlling for age, amount and type of alcohol and tobacco consumption, and state of dentition. Results showed that cancer of the supraglottis was associated with exposure to oil and grease (odds ratio = 2.4; 95% confidence interval 1.0-5.8), and with exposure to cement (odds ratio = 4.2; 95% confidence interval = 1.1-16.4). Cancer of the glottis was also associated with exposure to dye (odds ratio = 6.4; 95% confidence interval = 0.7-56.6). Exposure to flour occurred more frequently among controls than among patients with pharyngeal or oral cancer. This might reflect an association between this occupational exposure and some particular types of cancer included in the control group. 