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Benzene

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Overview


Benzene, also known as benzol, is an organic chemical compound with the formula C6H6. It is sometimes abbreviated PhH. Benzene is a colorless and flammable liquid with a sweet smell and a relatively high melting point.

It is an aromatic hydrocarbon produced by the burning of natural products. It is used in the manufacture of numerous products and it is a human carcinogen (#OSHA).

 

Just the facts


Physical Information

Name: Benzene

Use: additive in gasoline, industrial solvent

Source: glues, Tobacco smoke, gases

Recommended daily intake: none

Absorption: inhalation

Toxicity/symptoms: a known carcinogen

Chemical Structure

 

Chemical Description


Benzene is a clear, colorless liquid at room temperature and it readily evaporates in to the air. Its vapor is heavier than air so it will stay close to the ground (#CDC). Small traces of benzene*can be observed whenever carbon-rich materials undergo combustion.

Until World War II, most benzene production came as a byproduct of smelting steel. As demand increased in the 1950s because of its heightened importance as an industrial solvent, benzene began to be created using petroleum. Benzene production has diminished over the years due to its carcinogenic effects.

Uses


Benzene was first used in the 19th and early 10th century as an aftershave lotion and for douches because of its pleasant smell. It was also used around this time as an industrial solvent to degrease Metals, to decaffeinate coffee, and later was used as an additive to petrol because it increases the octane rating and reduces knocking in the engine. It was replaced by tetraethyl lead but has benzene has recently began to be used again as Lead use is being retracted. The use is very limited due to concerns over its toxicity and ability to leach into the groundwater (It is around 2% of gasoline in the US but can be up to 5% in other countries).

Benzene use today is immense, measured in the billions of pounds making it one o the top 20 most widely used Chemicals List. It is mainly used in the production of other chemicals such as dyes, drugs, Pesticides, and products such as rubber, nylon, and glues to name only a few.

Sources


It is formed from both natural processes and human activity (#CDC). Natural sources of benzene include volcanoes and forest fires. Numerous household products including glues, Tobacco smoke, and crude oil and gasoline (#CDC). Food and water have been contaminated before.

Health Effects


Acute exposure to benzene can lead to nervous system ailments such as dizziness, drowsiness, and eventual unconsciousness. Chronic exposure has more pernicious effects. Liver enzymes convert benzene to more toxic metabolites which can affect the bone marrow by crippling blood cell production , causing anemia, and can lead to leukemia.

It is also a known carcinogen and may lead to higher levels of leukemia.

Precautions


People should limit their exposure to benzene and monitor their environment carefully and use protective equipment if necessary. See the OSHA Safety and Health Tips on Benzene: Possible Solutions

Regulation


The US EPA recommends that benzene not exceed 5 ppb in drinking water. The US Occupational Health and Safety Administration set a standard of 1 ppm of benzene in the air over an 8-hour period with an action level set at 0.5 ppm in an effort to encourage reduction in the workplace.

Current Events


Unexplained benzene found in well in Florida in 2005 was never brought to the attention of the public. See the Miami New Times article


References


EPA. "Toxicological Review of Benzene - Noncancer Effects. September 1998.

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