1. INTRODUCTIONBenzene (also known as benzene) is a colorless, highly flammable liquid with a sweet odor. It evaporates in the air very quickly and partially dissolves in water. Most people can start to smell benzene in the air at around 60 ppm air and recognize it as benzene at 100 ppm. It was first discovered and extracted from coal tar in the 1980s and later from oil due to the dramatic increase in its demand. Since then, various industries have used benzene to produce other chemicals, such as styrene, cumene and cyclohexane. Benzene is also an important ingredient in the production of some types of rubbers, lubricants, dyes, detergents, drugs and pesticides. Therefore, individuals employed in these industries may be exposed to levels of benzene in the air much greater than those normally encountered by the general population. [1]Concerns have been reported about potential health effects from benzene exposure, such as bone marrow depression leading to anemia, leukopenia, and thrombocytopenia, as well as a decrease in circulating blood cells. Furthermore, laboratory studies in humans and animals have indicated that benzene exerts its effect by damaging the genetic material of cells. Therefore, benzene is classified as a confirmed human carcinogen. [2]In Singapore, every employer has the responsibility to take reasonably practicable measures to ensure that no one in the workplace is exposed to benzene above the Permissible Exposure Level (PEL) specified in the regulations. The prescribed permissible (long-term) exposure limit for benzene is 1 ppm over an 8-hour workday and a 40-hour workweek. [3] These exposure standards are generally established based on risk assessment using data obtained from human and/or animal health effects studies. [4]So, this… half of the paper… [8] Animal and human studies provide clear evidence of a causal relationship between occupational exposure to benzene leading to aplastic anemia. Lan et al. [7] reported that bone marrow toxicity was detected in a group of workers after several months of exposure to airborne benzene at or below 1 ppm. Therefore, the local PEL setting should be changed to the TLV-TWA of 0.5 ppm recommended by ACGIH to minimize the potential for adverse health effects posed by occupational exposure. Alternatively, the entire world should adopt a single internationally agreed system such as the Globally Harmonized System (GHS) under the auspices of the United Nations. The GHS allows the country to adopt a single and unilateral system, reduce duplication of testing and evaluation of chemicals, facilitate trade in chemicals where hazards can be adequately assessed and identified on an international basis. [15]