Assessment of the Workers' Exposure to Styrene in a Polymer Manufacturing Industry: Correlation Between Air and Biological Monitoring Methods

Background and Objective: Styrene is widely used in the production of many products, such as paints, glues, and plastics. There is a high potential for exposure to this toxic solvent in workplaces. The present study aimed to assess the levels of exposure to styrene via air and biological monitoring methods and determine the correlation between them in styrene-exposed workers. Materials and Methods: A total of 44 workers from a polymer manufacturing industry were studied, and the workers’ inhalational exposure to styrene was measured. In addition, the levels of urinary mandelic acid were determined. Data was analyzed using the SPSS (version 22.0) software. Results: The time-weighted average (TWA) exposure to styrene was equal to 18.35±11.02 ppm. The mean urinary mandelic acid was 150 mg/g creatinine. Moreover, a significant correlation was observed between the styrene concentration and the urinary mandelic acid (r=0.841). The correlation was stronger in workers with no skin exposure than in those with this type of exposure. Furthermore, a significant correlation was observed based on working hours per day (less than or more than 8 hours per day) so that the correlation was better for workers with shorter exposures (r= 0.922 vs. 0.713). Conclusion: The findings of the present study indicated a relatively strong correlation between inhalational exposure to styrene and the levels of mandelic acid in urine. In addition, smoking and working conditions, such as skin exposure and working hours per day, can affect the levels of urinary mandelic acid. Therefore, these factors should be considered in the exposure assessment of workers exposed to styrene.