Benzene (carcinogen)
Benzene is a clear, colorless to light yellow liquid known for its aromatic odor and is classified as a known human carcinogen since 1980. Its chemical formula is C6H6, and it is highly volatile and flammable. Benzene is used extensively in various industries, serving as a solvent in products like inks, paints, and rubber, and is also found in gasoline and tobacco smoke. Exposure occurs primarily through inhalation, skin contact, and oral ingestion, making it a risk for individuals in many settings, especially children and pregnant women. The chemical is associated with several types of blood cancers, including various leukemias and lymphomas, due to its ability to cause chromosomal damage to bone marrow. Symptoms of these cancers may include fatigue, night sweats, and frequent infections. Notably, benzene levels in drinking water are regulated in the United States to ensure public safety, with strict limits set to prevent health risks. The history of benzene traces back to the early 19th century, evolving through significant scientific discoveries and industrial applications over the years.
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Benzene (carcinogen)
ROC STATUS: Known human carcinogen since 1980
ALSO KNOWN AS: Benzol, phenyl hydride, 1,3,5-cyclohexatriene
RELATED CANCERS: Cancers of the blood and blood-forming organs, including acute myelogenous, monocytic, erythroblastic, and lymphocytic leukemias, lymphomas, and Zymbal gland carcinomas
DEFINITION: Benzene (chemical formula C6H6) is a clear, colorless to light yellow, volatile, and flammable liquid that has an aromatic odor. It is slightly soluble in water, is sensitive to heat, and mixes easily with alcohol, ether, chloroform, acetone, carbon tetrachloride, carbon disulfide, oils, and glacial acetic acid. It forms a solid below 42 degrees Fahrenheit (5.5 degrees Celsius).
In the United States, the Safe Drinking Water Act has legal control over benzene levels in drinking water, which cannot exceed 5 parts per billion (ppb). Exposure at 19,000 to 20,000 parts per million for five to ten minutes is fatal, as reported by the US Centers for Disease Control and Prevention (CDC). The US Food and Drug Administration prohibits the use of benzene in other products.
Exposure routes: Inhalation, skin contact, and oral ingestion are the most toxic and dangerous routes.
Where found: Benzene is an industrial chemical that is widely used as a solvent and used in inks, rubber, lacquers, paint removers, gas additives, glue backing for carpeting, high-solvent paints, some furniture wax, automobile exhaust, tobacco smoke, secondhand smoke, taxidermy, firefighting, metal preparation and pouring, petroleum refining, industrial cleaning, drinking water, and closed processes to synthesize organic chemicals. It is also used to make dyes and insecticides and in the processing of numerous chemicals.
At risk: Children and pregnant women are at higher risk. However, anyone exposed to benzene is at risk. For example, the presence of benzene in gasoline makes exposure to it a risk for anyone filling an automobile gas tank. In 2024, benzene was found in topical acne medications containing benzoyl peroxide, raising alarm for consumers. Products containing the acne-fighting medicine, when exposed to high temperatures, produced high levels of benzene. Guidelines regarding the proper storage of these medications were provided to consumers.
Etiology and symptoms of associated cancers: According to the American Cancer Society, benzene causes chromosomal damage to the bone marrow, and the blood-forming tissue, which can then lead to leukemias and lymphomas. The CDC reported in 2018 that benzene can also cause insufficient red blood cell production and alter antibody levels. Exposure to as little as less than one part per million can lower white blood cell counts.
Symptoms of leukemias and lymphomas include fever, night sweats, fatigue, bleeding and easy bruising, bone pain, frequent infections, swollen lymph nodes, and weight loss.
History: Benzene is a natural component of crude oil. In 1825 Michael Faraday performed distillation experiments and extracted a gas from the oil. The gas burned, and he named it “bicarburet of hydrogen.” The chemical structure of benzene remained elusive until 1865, when Friedrich August Kekulé von Stradonitz hypothesized a hexagonal structure. A. W. Hoffman derived benzene from the distillation of coal in 1846. As its usefulness in many industrial applications became apparent, the uses of and demand for benzene increased along with oil exploration. Linus Pauling, the Nobel Prize-winning physicist, was one of many scientists who attempted to elucidate the unique hybrid structure of benzene, which was confirmed in 1931. Prior to World War I, the main use of benzene was in gasoline blending, as it increased octane. It was used extensively in industry in World War II, and almost all organic chemistry-related industries involve petroleum (benzene-containing) products.
Bibliography
“Benzene and Cancer Risk.” American Cancer Society, 1 Feb. 2023, www.cancer.org/cancer/risk-prevention/chemicals/benzene.html. Accessed 17 June 2024.
“CDC - Facts About Benzene.” CDC Emergency Preparedness, 4 Apr. 2018, emergency.cdc.gov/agent/benzene/basics/facts.asp. Accessed 17 June 2024.
Chilcott, R. P. HPA Compendium of Chemical Hazards: Benzene. Health Protection Agency, 2011.
Howard, Jacqueline. “Cancer-causing Chemical Can Form at ‘Unacceptably High Levels’ in Certain Acne Products, Independent Lab Claims.” CNN, 6 Mar. 2024, www.cnn.com/2024/03/06/health/benzene-acne-products-valisure/index.html. Accessed 17 June 2024.
Lan, Qing, et al. "Hematotoxicity in Workers Exposed to Low Levels of Benzene." Nature 306.5702, 2004, pp. 1774–76.
Snyder, Robert. "Leukemia and Benzene." International Journal of Environmental Research and Public Health, vol. 9.8, 2012, pp. 2875–93.
US Department of Health and Human Services, Public Health Service, National Toxicology Program. 12th Report on Carcinogens. Research Triangle Park: US Dept. of Health and Human Services, 2011.