Benzene


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Introduction

Benzene, is a colorless, sweet-smelling, highly flammable liquid. It evaporates readily and is slightly soluble in water. Benzene is an important component of crude oil, and most industrial benzene comes from petroleum. [1]

Uses of Benzene

Benzene is a very important industrial chemical that serves as a building block for many other chemicals used in a vast array of products. Examples include styrofoam, resins, synthetic fabrics, dyes, drugs, pesticides, rubber, detergents, and lubricants. [1]

Structural diagram: National Institutes of Health


Benzene in the Environment

Benzene released to the ground may evaporate, undergo degradation by microorganisms, and/or move down through the soil, perhaps reaching the water table. Benzene in soils that contain lots of oxygen tends to biodegrade relatively quickly. Benzene in groundwater or poorly oxygenated soil tends to persist for a long time (years or even decades). Benzene is somewhat soluble in groundwater and can travel laterally hundreds of feet as it moves with groundwater flow. Benzene in the air tends to react with other chemicals and generally breaks down within a few days. Benzene does not bioaccumulate in the tissues of plants and animals. [1]

Exposure to Benzene

Benzene is common in the environment, and there is virtually no way to completely avoid exposure. Most exposure occurs through breathing air that contains benzene. Major sources include tobacco smoke, motor vehicle exhaust, industrial emissions, and gasoline stations. Other sources include various products that contain benzene, forest fires, and volcanoes. About half of human exposure to benzene comes from tobacco smoke; the average smoker breathes about ten times as much benzene as the average non-smoker. [1]

Health Effects of Benzene

The NIOSH Pocket Guide to Chemical Hazards [3] lists the following symptoms related to benzene exposure:

  • Eye, skin, nose, respiratory system irritation

  • Dizziness

  • Headache, nausea, staggered gait

  • Anorexia

  • Lassitude (weakness, exhaustion)

  • Dermatitis

  • Bone marrow depression

  • Potential occupational carcinogen

  • When last checked on 6 December 2015, U.S. EPA's Integrated Risk Information System [4] stated that "benzene is characterized as a known human carcinogen for all routes of exposure based upon convincing human evidence as well as supporting evidence from animal studies". The International Agency for Research on Cancer [2] has determined that benzene is a known human carcinogen.

    References

    [1] "Toxicological Profile for Benzene, 2005 Draft for Public Comment", published by the Agency for Toxic Substances and Disease Registry, U.S. Dept. of Health and Human Services

    [2] International Agency for Research on Cancer

    [3] NIOSH Pocket Guide to Chemical Hazards, published by the National Institute for Occupational Safety and Health

    [4] Integrated Risk Information System, published by the United States Environmental Protection Agency