Benzene is a common but toxic chemical found in petroleum products. Studies suggest even low-level benzene exposure can greatly increase the risk of leukemia.

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Benzene Molecular Structure

Fast Facts

  • Benzene is a chemical found in petroleum products and solvents.
  • U.S. and international watchdogs recognize benzene as a cause of leukemia and other cancers.
  • Studies show benzene exposure can increase the risk of certain cancers by as much as 40 percent.

Benzene is one of the most commonly used chemicals in the U.S. Several federal agencies list it as a known cause of cancer. In 1987, the government significantly lowered the benzene exposure limit in the workplace. Medical research suggests the allowed amount in 2018 is still too high.

What is Benzene?

Benzene is a liquid compound. It is colorless, toxic and flammable. It has a sweet, gasoline-like aroma. But breathing it can cause serious complications including leukemia and nerve damage.

Did You Know

Benzene is one of the 20 most-used chemicals in the U.S.

Where Benzene Is Found

Oil companies add benzene to gasoline to boost octane. It gives gasoline much of its aroma. The chemical is also found in car exhaust.

Close-up Image of gas gump
Benzene is used to boost octane in gasoline.

Benzene is also used to make other chemicals. Manufacturers rely on benzene for products ranging from medicine to industrial solvents.

How Benzene Exposure Happens

Most benzene exposure happens when people breathe in air containing benzene. People can also absorb it as a liquid through their skin. This can happen if people spill gasoline or solvents on themselves.

Where Benzene Exposure Happens

Benzene exposure usually happens in an industrial setting. But an act as simple as filling a gas tank can result in low-level exposure.

Chemical and petroleum industry workers may face long-term exposure. Mechanics and other people who work around engines, fuel or oil also face exposure risks.

Typical Workplaces Prone to Benzene Exposure:

  • Auto repair shops
  • Bus garages
  • Chemical plants
  • Oil pipelines
  • Petroleum refineries
  • Railroads
  • Ships and tankers
  • Shoe factories

Being Exposed to Benzene at Work

The U.S. Occupational Safety and Health Administration (OSHA) sets strict limits on benzene in the workplace.

OSHA limits benzene exposure in the air to one part per million (ppm). That equals one ounce of benzene for every 350,000 cubic feet of air. Three hundred fifty thousand cubic feet is about the size of four Olympic swimming pools.

Safety Study

Research shows the benzene exposure limit in the workplace may be too high.

The level can go up to 5 ppm for no more than 15 minutes. Employers must provide protective equipment like respirators for people working around higher levels.

In the 1980s, the benzene exposure limit was 50 times greater. Research found the older, higher levels were more dangerous.

But a 2004 study suggested newer levels may still be too high for safety. That study examined Chinese shoe-factory workers. Their exposure was less than the U.S. benzene exposure limit. International researchers found the workers exhibited signs of increased leukemia risk. The study appeared in Science.

Benzene Health Risks

Studies link benzene exposure to several types of leukemia. Leukemia is a cancer of the blood-forming organs in the body. It can also cause other blood-related complications. Benzene exposure can damage skin, eyes and affect the nervous system.

Benzene Exposure Complications:

  • Acute lymphocytic leukemia (ALL)
  • Acute myeloid leukemia (AML)
  • Chronic lymphocytic leukemia (CLL)
  • Chronic myeloid leukemia (CML)
  • Myelodysplastic Syndrome (MDS)
  • Non-Hodgkin lymphoma
  • Multiple myeloma
  • Aplastic anemia
  • Bone marrow dysplasia
  • Central nerve system damage
  • Excessive bleeding
  • Immune system damage

Chronic Myeloid Leukemia (CML)

Chronic myeloid leukemia (CML) is among the most serious complications of benzene exposure. It starts in bone marrow. When CML grows, it expands into the blood. From there, it can spread through the body. It may attack the spleen.

Symptoms of CML:

  • Bone pain
  • Enlarged spleen
  • Fever
  • Joint pain
  • Night sweats
  • Pain or “fullness” in the abdomen
  • Shortness of breath
  • Swelling under the left side of the ribcage
  • Unexplained weight loss
  • Weakness or fatigue

CML is slow growing. But in some cases it can turn into a much faster growing leukemia. Once that happens, it becomes more difficult to treat.

Can Benzene Cause Cancer?

Leukemia is benzene’s most serious, long-term health risk. Studies have found even low benzene exposure can increase leukemia risk.

A 2015 benzene study looked at leukemia risks from low exposure. Researchers examined medical histories of 25,000 Norwegian oil rig workers. All had worked on off-shore rigs for at least 20 days. The researchers found even with low exposure levels, the leukemia risk was high. They published their work in the British Journal of Cancer.

The researchers said their findings were in line with previous low-exposure benzene studies. A 2007 study in Cancer Causes & Control found a three-fold increased risk for acute myeloid leukemia (AML). A 2003 study in Epidemiology found a seven-fold increase in acute non-lymphocytic leukemia risk.

The 2015 study also found that the risk was even greater before 1980. It was about that time that governments set new benzene exposure limits. U.S. and international agencies have long known of benzene’s link to cancer.

What Health & Safety Agencies Say About Benzene:

  • “Known human carcinogen” – U.S. Environmental Protection Agency (EPA)
  • “Carcinogenic to humans” – International Agency for Research on Cancer (IARC)
  • “A known human carcinogen” – National Institutes of Health (NIH)
  • “Known to be a human carcinogen” – National Toxicology Program (NTP)

A 2012 study found benzene exposure can increase the risk of chronic myeloid leukemia (CML) by 23 percent. That study appeared in the American Journal of Industrial Medicine.

In 2010, researchers analyzed 15 benzene exposure studies. They estimated there was a 40 percent average risk of leukemia from benzene exposure. They also linked higher exposure to higher risk of leukemia. They found the risk more than doubled for people with the greatest benzene exposure. The study appeared in the journal Environmental Health.

How to Avoid Benzene Exposure

People who work around benzene should wear safety gear to limit exposure. Proper clothing can prevent skin contact. Protective eyewear can prevent benzene from getting in the eyes. People should wear respirators if working around higher levels of benzene.

People filling their gas tanks should avoid breathing in gasoline fumes. They should use pumps with vapor capture devices to reduce exposure risks.

Signs and Symptoms of Benzene Exposure

Signs and symptoms of benzene exposure range from simple irritation to serious medical conditions. They can happen within seconds of exposure. Some symptoms can take weeks to show up.

Benzene Exposure Signs and Symptoms:

  • Irritation of the eyes, skin, nose, or respiratory system
  • Dizziness
  • Headache
  • Nausea
  • Staggered gait
  • Anorexia
  • Weakness or exhaustion
  • Dermatitis

How to Treat Benzene Exposure

Immediate treatment includes moving into fresh air. Those exposed to Benzene should wash their skin or flush their eyes after benzene contact. People should quickly remove any clothing that has benzene on it. They should cut off any contaminated clothing rather than pulling it over their head.

What to Do If You’ve Experienced Benzene Exposure

People should speak to a doctor if they think they experienced long-term benzene exposure. Doctors use blood, breath or urine tests to detect benzene exposure. While tests can measure benzene exposure, they cannot predict long-term health effects.

Industry Faces Benzene Lawsuits

Workers began filing lawsuits over benzene exposure in the 1990s. This followed OSHA’s decision to lower the benzene exposure limit. It also came as other institutions declared benzene a known cause of cancer.

Court documents show that large oil and chemical companies knew about benzene’s risks since the 1940s. Workers who developed leukemia after benzene exposure claim the companies were negligent. Their lawsuits claim the companies could have done more to protect them.

Please seek the advice of a medical professional before making health care decisions.


Terry Turner is an Emmy-winning, former television journalist. He is an associate member of the American Bar Association, the ABA’s Health Law group and a member of the Alliance of Professional Health Advocates. He holds six certificates in Health Literacy for Healthcare Professionals from the Centers for Disease Control and Prevention. As a Washington-based investigative reporter, he routinely reported on health and medical policy issues before Congress, the FDA and other federal agencies. Terry received his B.A. in Media Arts from Lyon College.

Hide Sources

  1. National Institutes of Health. (2018, February 19). Benzene. PubChem Open Chemistry Database. Retrieved from
  2. American Cancer Society. (2016, January 5). Benzene and Cancer Risk. Retrieved from
  3. Agency for Toxic Substances & Disease Registry. (2011, March 3). Benzene. Retrieved from
  4. U.S. Department of Labor. (n.d.). Benzene. Occupational Safety and Health Administration. Retrieved from
  5. Stokstad, E. (2004, December 2). Blood Cells Battered by Benzene. Science. Retrieved from
  6. Qing, L., et al. (2004, December 3). Hematotoxicity in Workers Exposed to Low Levels of Benzene. Science. Retrieved from
  7. Stenehjem, J.S., et al. (2015, March 24). Benzene Exposure and Risk of Lymphohaematopoietic Cancers in 25,000 Offshore Oil Industry Workers. British Journal of Cancer. Retrieved from
  8. Kirkeleit, J. et al. (2007, September 29). Increased Risk of Acute Myelogenous Leukemia and Multiple Myeloma in a Historical Cohort of Upstream Petroleum Workers Exposed to Crude Oil. Cancer Causes & Control. Retrieved from
  9. Glass, D.C. et al. (2003, September). Leukemia Risk Associated with Low-Level Benzene Exposure. Epidemiology. Retrieved from
  10. Vlaanderen, J. et al. (2012, June 21). Occupational Benzene Exposure and the Risk of Chronic Myeloid Leukemia: A Meta-Analysis of Cohort Studies Incorporating Study Quality Dimensions. American Journal of Industrial Medicine. Retrieved from
  11. Khalade, A., et al. (2010, June 28). Exposure to Benzene at Work and the Risk of Leukemia: A Systematic Review and Meta-Analysis. Environmental Health. Retrieved from
  12. Azari, M.R., et al. (2012, August 26). Evaluation of Occupational Exposure of Shoe Makers to Benzene and Toluene Compounds in Shoe Manufacturing Workshops in East Tehran. Tanaffos. Retrieved from
  13. Lombardi, K. (2014, December 4). Benzene and Worker Cancers: “An American Tragedy.” Center for Public Integrity. Retrieved from
  14. Canadian Centre for Occupational Health and Safety. (n.d.). NIOSH Pocket Guide to Chemical Hazards; Benzene. Retrieved from
  15. U.S. Centers for Disease Control and Prevention. (2013, February 14). Emergency Preparedness and Response. Benzene. Retrieved from
  16. Lombardi, K. (2014, December 4). Benzene and Worker Cancers: “An American Tragedy.” Center for Public Integrity. Retrieved from