Evaluation of Occupational Exposure with Vinyl Chloride Monomer in the Plastic Production Industry in Tehran

Backgrounds and Growth of the plastics industry in recent decades has been dramatic. Poly Vinyl Chloride is one of the most widely used plastics in the world that granules in the thermal process decompose to Vinyl Chloride Monomer and is released in work air environment. This study aimed to evaluate occupational exposure and estimate workers'' exposure with vinyl chloride monomer risk. A cross-sectional study of 100 workers at two Plastic factories in Tehran (A، B) was performed. Personal monitoring of workers to Vinyl Chloride Monomer was conducted by Optimized Method No. 1007 from NIOSH. Atmospheric conditions، such as temperature، pressure، air velocity، and relative humidity were measured simultaneously along with personal monitoring. Quantitative risk assessment of workers was computed in the form of Standard Mortality Rate and incident rate cancer. Statistical analysis of data was conducted by SPSS version 19. Climatic parameters in the plant A and B for a relative humidity were 43. 77± 16. 71 and 37. 16±14. 45 % and temperature 20. 95± 3. 34 and 21. 05± 2. 20 ºC، air pressure 87. 48 ± 0. 54 and 87. 41 ± 0. 64 kPa and air velocity 0. 13± 0. 08 and 0. 10 ± 0. 06 meters per second were measured respectively. Occupational exposure to Vinyl Chloride Monomer plants A and B were 1. 01 ± 0. 51 and 0. 72 ± 0. 30 as ppm respectively. Quantitative risk of exposed workers based on Standard Mortality Rate was estimated 1. 06 ± 0. 03 times of the population without exposure. Incident rate cancer based on accounting measures of Integrated Risk Information System was calculated per 1000 person exposure population. The correlation of Standard Mortality Rate and the risk of cancer incidence was statistically significant (R2 =0. 88). Thirty one percent of workers had higher exposure to Vinyl Chloride Monomer than the occupational exposure limits (1 ppm). In the present workers’ exposure in this study is lower than international workforces reported in decades ago، but higher than studies recently published. The results clearly describes occupational hazard of workers in the current Iranian recession situation. The application of control system in the form of engineering control measure، especially in the coming years with projected economic growth، is justified for securing workers health and well-being.