Iran Occupational Health

 Background and aims: The purpose of this study was to assess the prevalence of respiratory symptoms (phlegm, cough, shortness of breath and wheezing) and lung functional impairments associated with occupational inhalation exposure to carbon black (CB) dust among employees of a rubber industry.

  Methods: All of the eligible, CB exposed, employees of the industry (72 subjects) as well as 69 unexposed employees from the same industry (referent group) were investigated.

 Subjects were interviewed and were given standardized respiratory symptom questionnaires to answer. Furthermore, pulmonary function tests (PFTs) were measured before and after the work shift for exposed subjects and once during the work shift for referent subjects. Furthermore, to assess the extent to which workers were exposed to CB, using standard methods, inhalable and respirable dust fractions of it were measured.

  Results: Levels of exposure to inhalable and respirable CB dust were estimated to be 6.2±1.7 and 2.3±0.29 mg/m³, respectively. Symptoms of respiratory disease such as regular cough, phlegm, wheezing and shortness of breath were significantly more prevalent among exposed workers. Furthermore, compared to unexposed group, significant decreases in mean values of VC, FVC and FEV1 of exposed workers were noted.

  Conclusion: The findings of this study show that exposure to high atmospheric concentrations of CB may result in a significant increase in the prevalence of respiratory symptoms and significant decrements in the mean value of some parameters of pulmonary function with a spirometric pattern consistent with restrictive pulmonary disorders.

  Keywords: Carbon black, Rubber industry, Respiratory disease symptoms, Lung functional impairments