1,3-Butadiene and cancer
1,3-Butadiene is a flammable hydrocarbon composed of four carbon atoms and six hydrogen atoms, known for its use in producing synthetic rubber, resins, and polymers. It has been recognized as a known human carcinogen since 2000 and is associated with several types of cancer, including leukemia and other hematopoietic cancers. Exposure to 1,3-butadiene primarily occurs through inhalation of emissions from vehicles, waste incineration, and cigarette smoke, as well as through contaminated drinking water and dermal contact with gasoline. The compound is highly reactive and can form epoxides that lead to genetic alterations in tumor-suppressor genes, similar to other recognized carcinogens.
Historically, the search for synthetic alternatives to natural rubber during World War II intensified the production of 1,3-butadiene. Research on workers in synthetic rubber facilities has shown a strong correlation between exposure and an increased risk of developing various cancers. Regulatory agencies, including the EPA and OSHA, have established stringent guidelines and limits regarding exposure to 1,3-butadiene, recognizing its potential health risks, especially for vulnerable populations such as children. Overall, awareness of the dangers associated with this chemical is crucial for both occupational safety and public health.
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1,3-Butadiene and cancer
ROC STATUS: Known human carcinogen since 2000
ALSO KNOWN AS: Vinylethylene, bivinyl, buta-1,3-diene, α,γ-butadiene
RELATED CANCERS: Leukemia, lymphosarcoma, reticulosarcoma, hematopoietic cancers
DEFINITION: 1,3-Butadiene is a hydrocarbon molecule made up of four atoms of carbon and six atoms of hydrogen. The first and last pairs of carbon atoms are held together by two chemical bonds or four electrons. The two and three carbons share a single pair of electrons. This atomic arrangement makes 1,3-butadiene highly flammable and extremely reactive.
Exposure routes: Inhalation from the exhaust from motor vehicles, waste incineration, wood fires, and cigarette smoke; ingestion of contaminated drinking water from near waste or production facilities; dermal contact with gasoline
Where found: Industries involved in the synthesis of rubber-like materials, resins, and polymers
At risk: Workers who deal with synthetic rubber, organic chemicals, and resins
Etiology and symptoms of associated cancers: In all species studied, including humans, 1,3-butadiene has been shown to be oxidized to rings that involve two of the carbon atoms and one atom of oxygen. Such epoxides are chemically similar to the known carcinogen ethylene oxide. Tumor production in both rodents and humans involves a reaction with deoxyribonucleic acid (DNA), producing genetic alterations in tumor-suppressor genes.
History: The shortage of natural rubber in World War II caused an intense search for synthetic latex. It was determined that 1,3-butadiene reacts readily with other similar hydrocarbons to produce a wide variety of polymeric substances. An example is copolymerization with styrene, a molecule involving the carcinogen benzene. Uncertainty in early studies of 1,3-butadiene carcinogenicity resulted when conditions also involved benzene. According to the US National Toxicology Program's (NTP) Report on Carcinogens, Fifteenth Edition, in 1986, Chemical & Engineering News reported that more than 75 percent of 2 million metric tons of 1,3-butadiene produced in a typical year were consumed by the synthetic rubber industry. The compound is also involved in nylon synthesis, acrylic production, and the production of fungicides.
Studies of workers in synthetic rubber plants beginning in 1943 gave conflicting evidence concerning the carcinogenicity of 1,3-butadiene. Later animal studies with rats and mice exhibited a strong pattern of incremental risk for a variety of cancers. More carefully controlled studies of production workers in the early 1990s documented 1,3-butadiene’s carcinogenic nature. NTP first listed 1,3-butadiene as "reasonably anticipated to be a human carcinogen" in RoC, Fifth Edition (1989) and updated its status to "known to be human carcinogen" in RoC, Ninth Edition in 2000.
Extensive federal regulation of 1,3-butadiene exists. The US Department of Transportation (DOT) lists the chemical as hazardous and requires special marking, labeling, and transporting precautions. The US Environmental Protection Agency (EPA), acting under the Clean Air Act (1970), lists 1,3-butadiene as one of thirty-three hazardous air pollutants that present the greatest threat to public health and requires that as little as ten pounds of the substance must be reported. In 1996, the Occupational Safety and Health Administration (OSHA) set the permissible exposure limit for an eight-hour time-weighted average at one part per million and set the short-term exposure limit for fifteen minutes at five parts per million.
Further study of exposure to 1,3-butadiene revealed that children exposed to the chemical reported increased occurrence of childhood leukemia, asthma, brain tumors, retinoblastoma, asthma, and malignant germ cell tumors. Those in enclosed environments with exposure to tobacco smoke are at the greatest risk.
Bibliography
Agency for Toxic Substances and Disease Registry. "1,3-Butadiene ToxFAQs." ATSDR, Oct. 2012, www.atsdr.cdc.gov/toxfaqs/tfacts28.pdf. Accessed 20 June 2024.
Chen, Wan-Qi, and Xin-Yu Zhang. “1,3-Butadiene: A Ubiquitous Environmental Mutagen and Its Associations with Diseases.” Genes and Environment: The Official Journal of the Japanese Environmental Mutagen Society, vol. 44, no. 3, 10 Jan. 2022. BMC, doi.org/10.1186/s41021-021-00233-y.
"15th Report on Carcinogens." National Toxicology Program, Department of Health and Human Services, 2021, ntp.niehs.nih.gov/whatwestudy/assessments/cancer/roc. Accessed 20 June 2024.
"Known and Probable Human Carcinogens." American Cancer Society, 25 Mar. 2024, www.cancer.org/cancer/risk-prevention/understanding-cancer-risk/known-and-probable-human-carcinogens.html. Accessed 20 June 2024.
Phillips, Elisabeth S. Ferrocenes: Compounds, Properties and Applications. Nova, 2011.
US Dept. of Labor, Occupational Safety & Health Administration. "Occupational Exposure to 1,3-Butadiene." OSHA, 4 Nov. 1996, www.osha.gov/laws-regs/federalregister/1996-11-04. Accessed 20 June 2024.