Increased morbidity from nasopharyngeal carcinoma and chronic pharyngitis or sinusitis among workers at a newspaper printing company

Objectives: To determine the association between printing works and nasopharygeal carcinoma as well as other diseases. Methods: Demographic data were obtained for those who had worked in a particular newspaper company since its establishment in 1950. Through access to the data bank of the hospital records of the Labor Insurance Bureau for 1985-94, all workers were identified who had been admitted to hospital during their employment in the newspaper company. Multiple logistic regressions were performed to estimate the adjusted morbidity odds ratio (OR) for various diseases among the printing workers with cardiovascular diseases as the reference diseases. Biopsy specimens from patients with nasopharyngeal carcinoma were all subjected to in situ hybridisation of Epstein-Barr virus (EBV), and colocalisation of EBV and secretor component protein. Results: Of the 1564 people who had worked in this company, 579 of them were admitted to hospital at least once. Five out of 144 printing workers admitted to hospital were diagnosed with nasopharyngeal carcinoma compared with none of the other 435 non-printing workers admitted to hospital. The morbidity OR for nasopharyngeal carcinoma in printing workers was 57.0 (95% confidence interval (95% Cl) 2.8 to 1155.3). The morbidity OR for benign skin tumours was 28.0 (95% Cl 2.7 to 293.1). Chronic pharyngitis or sinusitis also showed significant relations with printing works with a morbidity OR 29.4 (95% Cl 1.7 to 514.7). Using all other diseases as the reference diseases for calculation of morbidity ORs still showed a similar trend. In situ hybridisation of EBV encoded small nuclear RNA-1 (EBER-1) showed tumour cells free of the EBV in each biopsy specimen. Colocalisation of EBER-1 and secretor component showed that some tumour cells contained both secretor component and EBV signal in each case. Conclusion: Printing works are associated with an increased risk of nasopharyngeal carcinoma, benign skin tumours, chronic pharyngitis or sinusitis, chronic liver diseases, and mechanical injuries. Induction of the development of nasopharyngeal carcinoma is probably not related to EBV infection in these patients.