Benzene is light yellow or colorless chemical that’s liquid at room temperature and highly flammable. It’s commonly found in man-made chemical products like gasoline and solvents, but people are also exposed to low levels in the air, soil and water. U.S. and international watchdog groups recognize that even low levels of benzene may increase the risk of cancers, including leukemia.
In the United States, benzene ranks among the top 20 chemicals in production volume, according to the Centers for Disease Control and Prevention. Manufacturers use it to make products such as rubber, dyes, lubricants, detergents, pesticides and drugs.
The most common way people are exposed to benzene is by breathing in air containing the chemical.
About 20 percent of benzene exposure in the United States comes from auto exhaust and industrial emissions. About half of the exposure to benzene in the United States comes from cigarette smoke.
Several federal agencies list the chemical as a known cause of cancer. Studies show benzene exposure can increase the risk of certain cancers by as much as 40 percent. Research suggests even low-level benzene exposure can greatly increase the risk of leukemia.
People who work in industries that use benzene are at the most risk of exposure to the highest levels of the chemical. 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.
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.
Benzene is used to make other chemicals, as well. 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.
People may also be exposed to benzene by using contaminated aerosol sunscreens or hair care products. In July 2021, Johnson & Johnson recalled several Aveeno and Neutrogena sunscreen sprays because of benzene contamination.
In December 2021, Procter & Gamble recalled dozens of dry shampoos after lab testing found benzene in the products. Affected brands included Pantene, Old Spice and Herbal Essence.
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.
- Auto repair shops
- Bus garages
- Chemical plants
- Oil pipelines
- Petroleum refineries
- 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.
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 that 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 that the workers exhibited signs of increased leukemia risk. The study appeared in a journal called 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.
- 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.
- Bone pain
- Enlarged spleen
- 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 that even with low exposure levels, the leukemia risk was high. They published their work in the British Journal of Cancer.
The researchers said that 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.
- “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 that 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 found a link between higher exposure and a higher risk of leukemia. They found that 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.
- Irritation of the eyes, skin, nose, or respiratory system
- Staggered gait
- Weakness or exhaustion
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 heads.
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 that the companies could have done more to protect them.
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