Respiratory symptoms and ventilatory capacity in rubber workers

Aim. The aim of the investigation was to study the prevalence of acute and chronic respiratory symptoms and diseases as well as acute and chronic lung function changes in workers occupationally exposed to aerosols in rubber industry. Subjects and Methods. Study included 409 rubber male workers and 172 unexposed control male workers. Acute and chronic respiratory symptoms were recorded by using modified British Medical Research questionnaire during the initial and follow-up study after a period of six years. Ventilatory capacity was measured by recording maximum expiratory flow-volume (MEFV) curves on which a forced vital capacity (FVC), one-second forced expiratory volume (FEV₁) and flow rates at 50% and the last 25% were read (FEF₅₀, FEF₂₅). Results. In comparison to the controls, a significantly higher prevalence of all respiratory symptoms except occupational asthma was found in rubber workers. Most of the chronic respiratory symptoms had a significantly higher prevalence in smokers than in nonsmokers. Rubber workers exposed for more than 10 years had also significantly higher prevalence of chronic respiratory symptoms than those with shorter exposure. Ventilatory capacity tests were most significantly decreased during work shift, particularly FEF₅₀ and FEF₂₅. All acute reductions were greater in rubber workers exposed for more than 10 years in comparison to those with greater exposure. In comparison to the controls, rubber workers demonstrated significantly lower all measured ventilatory capacity tests. A large number of rubber workers showed a decrease of lung function tests lower than 70% of the predicted normal values. The prevalence of all chronic respiratory symptoms in 311 rubber workers was higher during the follow-up study although not statistically significant (p > 0.05). Ventilatory capacity data as percentage of the predicted normal values were lower during the follow-up study in comparison to that during the initial study. A considerably lower mean annual decrease of ventilatory capacity was recorded in rubber workers in comparison to the predicted. Smokers had a larger mean annual decrease of all ventilatory capacity tests than nonsmokers. Conclusion. Our data indicate that exposure to noxious agents in rubber industry may be responsible for the development of acute and/or chronic impairment of lung function.