Benzene, C?H?, the best-known aromatic hydrocarbon and the first for which a valid structure was determined, consists of six connected segments -CH- with its two ends bonded together, creating a simple hexagonal ring. The properties of aromatic compounds are considerably different from non-aromatic structures.
Benzene is considered a hazardous substance due to its chemical toxicity and due to its being considered carcinogenic (It has not been proven that benzene is teratogenic, meaning causing birth defects). Its legal limit is very minimal: 5 parts per billion!
Uses of Benzene
One of the top 20 industrial chemicals, benzene is used to manufacture plastics, resins, fibers, pesticides, and detergents. It is found in petroleum products, and at one time it was used to boost octane level of gasoline.
Common Exposure Sources
Industries that manufacture or use benzene may present the highest risk of exposure. The atmosphere found at gas stations may have an elevated level of benzene.
According to the American Cancer Society, a single cigarette releases between 50 and 150 micrograms of benzene, making smoking one of the major sources of exposure to the carcinogen.
One surprising source of occasional benzene exposure is soda. The reaction between ascorbic acid (Vitamin C) and sodium benzoate (a preservative that kills bacteria, yeast, and fungi) is considered the likely source of the benzene.
Tests for Benzene Exposure
Human exposure to benzene is easily tested by one of three methods: blood testing, urine testing, or a breath test.
Counts of all components of the blood enables doctors to determine exposure to benzene and degree of damage done; however, benzene disappears quickly from the blood. If necessary, the physician may include a bone marrow evaluation.
Although one metabolite of benzene is phenol, measuring phenol in the urine is not an accurate indicator of benzene exposure, since other substances also produce phenol. Measurement of muconic acid or S-phenylmercapturic acid are much more reliable and sensitive indicators of benzene exposure.
The breath test, while simple, is very time sensitive. Specific damage done may be better evaluated using a blood test.
Symptoms of Exposure to Benzene
If there is any suspicion of benzene overexposure, it is important to receive medical attention promptly.
Chronic exposure to benzene is very damaging to the blood, as benzene attacks bone marrow, decreasing red blood cells, leading to anemia. Excessive bleeding may also be a symptom. Benzene takes a toll on the immune system, causing the body to have difficulty fighting off infection.
Acute exposure produces drowsiness, dizziness, headaches, confusion, tachycardia, tremors, and even death.
About the Author
Vincent Summers received his Bachelor of Science degree in chemistry from Drexel University in 1973. He furthered his education through the University of Virginia's Citizen Scholar Program program, taking many courses in organic and quantum chemistry. He has written technical articles since 2010.