Background & Objectives: Human environment is surrounded bychemicals that could directly or indirectly endanger human health. Some statistics of WHO is indicative of the fact that four million people are employed in the chemical industry throughout the world and one million people die or become disabled annually due to contact with chemicals. Moreover, 1-4 Millions chemical toxicity occur annually. The purpose of this study was to understand the risks involved in chemicals in the workplace, to assess the task risk, and to propose appropriate control measures in order to eliminate or reduce risk in the petrochemical industry. Materials & Methods: In this study, the chemicals were identified in Arak Petrochemical and features that are indicative of hazardous materials were identified and using TOPSIS, The hazard rate were determined. Then the job duties of employees and employee exposure rate with chemicals were calculated and finally, a risk rate for exposure to chemicals in job duties was determined. Results: It was found that chemicals do not have too high risk to employees however, but the high risky chemicals were five chemicals including naphtha, ammonia, acetic acid, chlorine, and methanol for operational staff and two chemicals, i.e. ammonia and chlorine for operation and maintenance staffs . Conclusion: It is better to have an alternative for the materials that their risk rang is high and very high, and their production is suggested to be avoided.
