Chronic bronchitis in oil industry workers exposed to hydrocarbons: role of cigarette smoking and gender differences

Materials and methods A retrospective case-control study was performed. Industry workers from an oil refinery were monitored for a 6yrs period. The air levels of aliphatic and aromatic hydrocarbons were monitored. During this period, all workers received regular clinical examinations, which included evaluation for smoking status, occupational exposure to hydrocarbons (aliphatic and aromatic), and the presence and severity of chronic bronchitis. The workers were divided into two groups of approximately 100 patients each: Group (1) males exposed to hydrocarbons; and Group (2) females exposed to hydrocarbons. Appropriately-matched control groups were also selected from non-exposed workers, who matched in age, gender, work history and lifestyle. The prevalence of smoking and chronic bronchitis was determined in each group. Linear regression analysis was used to assess the correlation between exposure to hydrocarbons and effects (chronic bronchitis), as well as smoking, and severity of chronic bronchitis.