Benzene is a colorless or light-yellow liquid chemical at room temperature. It is used primarily as a solvent in the chemical and pharmaceutical industries, as a starting material and an intermediate in the synthesis of numerous chemicals, and in gasoline. Benzene is produced by both natural and man-made processes. It is a natural component of crude oil, which is the main source of benzene produced today. Other natural sources include gas emissions from volcanoes and forest fires. Show
How are people exposed to benzene?People are exposed to benzene primarily by breathing air that contains the chemical. Workers in industries that produce or use benzene may be exposed to the highest levels of the chemical, although federal and state regulations have reduced these exposures in recent decades. Similarly, limits on the amount of benzene allowed in gasoline have contributed to reduced exposures. Mainstream cigarette smoke is another source of benzene exposure, accounting for about half of the total U.S. population exposure to this chemical. Among smokers, 90 percent of benzene exposures come from smoking. Benzene may also be found in glues, adhesives, cleaning products, and paint strippers. Outdoor air contains low levels of benzene from secondhand tobacco smoke, gasoline fumes, motor vehicle exhaust, and industrial emissions. Which cancers are associated with exposure to benzene?Exposure to benzene increases the risk of developing leukemia and other blood disorders. How can exposure be reduced?Don’t smoke and avoid exposure to secondhand tobacco smoke. Try to limit exposure to gasoline fumes. For workers who may be exposed to benzene on the job, the U.S. Centers for Disease Control and Prevention has information about how you can protect yourself and what to do if you are exposed. Selected References:
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If you would like to reproduce some or all of this content, see Reuse of NCI Information for guidance about copyright and permissions. In the case of permitted digital reproduction, please credit the National Cancer Institute as the source and link to the original NCI product using the original product's title; e.g., “Benzene was originally published by the National Cancer Institute.” 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% of benzene exposure in the United States comes from auto exhaust and industrial emissions. About half of the exposure to benzene in the U.S. comes from cigarette smoke. Smoking and Benzene Exposure Smokers take in 10 times more benzene a day than do nonsmokers. 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%. 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 current allowed amount 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. Breathing it can cause serious complications, including leukemia and nerve damage. Benzene is one of the 20 most-used chemicals in the U.S. Where Benzene Is FoundOil companies add benzene to gasoline to boost octane. It gives gasoline much of its smell. The chemical is also found in car exhaust.  Benzene is used to boost octane in gasoline. Benzene is used to make other chemicals, as well. Manufacturers rely on benzene for products ranging from medicine to industrial solvents. How Benzene Exposure HappensMost 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 they 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 HappensBenzene 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 face exposure risks. This can also occur on military bases that use benzene as a solvent, and service members as well as civilian workers may be at risk. Typical Workplaces Prone to Benzene Exposure:
Benzene exposure can also happen in places where water contamination occurs. Homes, schools and places of business that use contaminated water can expose people to higher-than-normal levels of the toxic chemical. For example, people who lived and worked at Marine Corps Base Camp Lejeune from 1953 to 1987 were exposed to benzene from contaminated water. Veterans and others who developed health problems because of benzene exposure can file Camp Lejeune lawsuits against the U.S. government. Being Exposed to Benzene at WorkThe U.S. Occupational Safety and Health Administration 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, about the size of four Olympic swimming pools. Research shows that 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 such as 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 lawsuits claim oil and chemical companies knew about the dangers of this chemical. View LawsuitsBenzene Health RisksStudies 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:
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:
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?Benzene can cause cancer, with leukemia being 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. 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 that benzene exposure can increase the risk of chronic myeloid leukemia (CML) by 23%. That study appeared in the American Journal of Industrial Medicine. In 2010, researchers analyzed 15 benzene exposure studies. They estimated there was a 40% 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. Because of benzene’s link to leukemia and the presence of benzene in contaminated water at Camp Lejeune, the VA recognizes leukemia and other blood-related cancers as eligible for disability benefits. An Agency for Toxic Substances and Disease Registry study found that military personnel stationed at Camp Lejeune were more likely to die of cancer than those stationed at Camp Pendleton, a base that didn’t have water contamination. How to Avoid Benzene ExposureThose 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. Anyone working around higher levels of benzene should wear a respirator. 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 ExposureSigns 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:
How to Treat Benzene ExposureImmediate treatment for benzene exposure 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. Speak to a doctor if you think you 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 LawsuitsWorkers 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. In August 2022, President Joe Biden sighed the Camp Lejeune Justice Act into law as a part of the Honoring Our Pact Act of 2022. The law allows veterans and family members exposed to benzene and other chemicals through water contamination at Camp Lejeune to sue the U.S. government for compensation for injuries. Does benzene cause permanent damage?Longer-term exposure to benzene may cause anemia, alterations to the immune system, and leukemia.
What is an acute effect of benzene on the human body?Acute (short-term) inhalation exposure of humans to benzene may cause drowsiness, dizziness, headaches, as well as eye, skin, and respiratory tract irritation, and, at high levels, unconsciousness.
What can benzene cause?Drowsiness, headaches, and dizziness have been reported when people breathed air with benzene levels of more than 10 ppm (10,000 ppbv) for a short time. Long-term exposure to benzene can increase the risk of developing leukemia. Exposure to benzene can cause anemia and weaken the immune system.
What is a form of toxicity that can be caused by chronic benzene exposure?Long-term (chronic) exposure. Repeated or prolonged exposure to benzene, even at relatively low concentrations, may result in various blood disorders, ranging from anemia to leukemia, an irreversible, fatal disease. Many blood disorders associated with benzene exposure may occur without symptoms.
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