Occupational exposure to styrene and its relation with urine mandelic acid, in plastic injection workers

Plastic injection industry workers are exposed to toxic gases and vapors, including styrene. This study aimed to measure exposure to styrene and its relation with urine mandelic acid among plastics injection workers of the electrical parts industry. This descriptive and analytical cross-sectional study was carried out in the plastic injection halls of the electronics industry, in winter 2017 and spring 2018. Styrene gas in the workers’ respiratory region was sampled by the NIOSH 1501 method and was analyzed by gas chromatography–mass spectrometry (GC/MAS). Mandelic acid concentration was determined by high-performance liquid chromatography (HPLC). Statistical data analysis was performed with STATA11. The mean of age and working experience in the population under study were 32.4 ± 8.1 and 6.4 ± 5 years, respectively. The average exposure to styrene was 83.2 ± 32.4 mg·m⁻³ and the mean of urine mandelic acid was 1570.1 ± 720.6 mg·g ceratinine⁻¹. There were 24 workers (45.3%) exposed to levels above permissible limits recommended by national and international organizations. There was a positive and significant correlation between exposure to styrene and urine mandelic acid (P = 0.006, r = 0.4). In multivariate regression, occupational exposure to styrene (P = 0.002, β = 0.5) was the strongest variable, predicting the amount of urine mandelic acid. Increased occupational exposure to styrene increases mandelic acid in the urine, and applying control measures to reduce exposure to styrene vapor is recommended in high exposure situations.