In 1997, the National Cancer Institute (NCI) and Chinese scientists found that occupational exposure to benzene is associated with increased risks of developing acute non-lymphocytic leukemia and related myelodysplastic syndromes and Non-Hodgkin lymphoma.

Benzene is a pale yellowish liquid with molecular formula C₆H₆, molecular weight of 78.11 and a flammable substance with aromatic odor. It is almost insoluble in water and soluble in organic solvents and oils. Benzene reacts violently with oxidizing agent, easy to vaporize. Benzene is absorbed into the body through inhalation, skin exposure, and ingestion.

Benzene is naturally occurring in petroleum products (crude oil, gasoline, etc.) and is added to unleaded gasoline to increase the octane number of unleaded gasoline and to suppress engine knocking.

The metabolism of benzene influences the whole process of hematopoietic differentiation that starts from hematopoietic stem cells. Hence, benzene exposure can cause all type of hematopoietic malignancies.