~~Introduction: Benzene is a primary chemical in the manufacture of plastics, rubbers, nylon, dyes, and so on. Long-term exposure to benzene has been known for years of damaging blood cells and bone marrow. Epidemiological studies have shown promising results that benzene exposure is significantly associated with an increased incidence of leukemia.
Discussion: In the past, the association of benzene exposure and leukemia was not convincing enough to establish the exposure standard due to its gradual development of the symptom. Until 1970s, the very first occupational exposure limit for benzene was announced as an administrative law by the United States Occupational Health and Safety Administration (U.S. OSHA). This standard was mainly based on results of the increased leukemia-diagnosed workers at a rubber plant in Ohio, USA, which was known as the Pliofilm cohort. Since then, the relationship between the development of leukemia and occupationally and non-occupationally benzene exposure had been studied by researchers worldwide.
Conclusion: Therefore, the epidemiologic studies have helped explain the relationship between benzene and leukemia. This article shows the necessity of occupational epidemiological research that can identify the toxicological or adverse health effects from chemical exposure, especially carcinogens such as benzene. Hence, epidemiological studies can be used as a reference for establishing occupational exposure limits (OELs).

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