What Is Benzene, and How Are People Exposed?
Benzene is a colorless liquid with a petroleum-like odor that evaporates into the air very quickly and is highly flammable, according to the Agency for Toxic Substances and Disease Registry. It is made naturally by burning wood and volcanic activity, and is also found in human-made sources like cigarette smoke and motor vehicle exhaust.
ATSDR says the most common ways to be exposed are smoking cigarettes or breathing other people’s cigarette smoke, and that motor vehicle exhaust and gasoline contain benzene, so people breathing contaminated air in heavy traffic or around gas stations may be exposed. The National Cancer Institute says mainstream cigarette smoke accounts for about half of total US population exposure to benzene, and that benzene may also be found in glues, adhesives, cleaning products and paint strippers.
ATSDR says breathing benzene for a long time can affect blood cells and bone marrow, and that reduced numbers of red and white blood cells seen in exposed workers can lead to anemia and a reduced ability to fight off diseases and infections. The CDC says long-term exposure to high levels of benzene in the air can cause leukemia, a blood-related cancer, and the US Department of Health and Human Services and the EPA consider benzene a known human carcinogen, with IARC classifying it as carcinogenic to humans.
Sources checked September 15, 2026. Every point below links the page it came from.
The sources behind this answer
- Government sourceATSDR says benzene is a colorless, highly flammable liquid with a petroleum-like odor, made naturally by burning wood and volcanic activity and found in cigarette smoke and motor vehicle exhaust. ATSDR ToxFAQs ↗
- Government sourceATSDR says the most common ways to be exposed to benzene are smoking or breathing secondhand smoke, and that motor vehicle exhaust and gasoline contain benzene. ATSDR ToxFAQs ↗
- Government sourceThe National Cancer Institute says mainstream cigarette smoke accounts for about half of total US exposure to benzene, and that benzene may also be found in glues, adhesives, cleaning products and paint strippers. National Cancer Institute ↗
- Government sourceATSDR says breathing benzene for a long time can affect blood cells and bone marrow, and that reduced red and white blood cells in exposed workers can lead to anemia and a reduced ability to fight infections. ATSDR ToxFAQs ↗
- Government sourceThe CDC says the Department of Health and Human Services has said benzene causes cancer in humans, and that long-term exposure to high levels in the air can cause leukemia. CDC ↗
- Government sourceATSDR says DHHS considers benzene a known human carcinogen, the EPA classifies it as a known human carcinogen, and IARC classifies it as carcinogenic to humans. ATSDR ToxFAQs ↗
Sources checked September 15, 2026. A brand statement is the company’s own claim, which we report but have not verified. Our grades are model-based estimates, not lab tests.