Benzene is a colourless liquid with a sweet odor. It is highly flammable and is formed by both natural processes and human activities.
Benzene is widely used in the United States; it's one of the top 20 chemicals for production volume. Some industries form benzene to produce other chemicals which are used to make plastics, resins, nylon and synthetic fibres. Benzene is also used to make some types of rubbers, lubricants, dyes, detergents, drugs and pesticides. Natural sources of benzene include volcanoes and forest fires. Benzene is also a natural part of crude oil, gasoline, and cigarette smoke.
Anthropogenic releases of benzene into the atmosphere result mainly from environmental auto mobile exhaust and refuelling, tobacco smoke and industrial emissions.
Benzene has a moderate water solubility of 1,78 g/l, but is highly volatile and can rapidly evaporate from surface waters to the atmosphere. It has a low adsorption to sediments or soils and will be removed from them to surface or ground water and the atmosphere. In the atmosphere it will be degraded within 8 days, while its half-life in water is 16 days.
Benzene has a low tendency to bioaccumulate, concentrations in goldfishes are typically only 4 times higher than those in the environment. Therefore it is not considered likely to biomagnify though food chains .
The most sensitive crustaceans experience acute toxicity at benzene concentrations above 3.3 mg/l although most other crustaceans tolerate concentrations up to 120 mg/l. The most sensitive fish species die at exposure to concentrations above 4.9 mg/l, although most species tolerate short exposures to benzene concentrations of up to 100 mg/l.
Concentrations in air typically range between 0.3 ppb (parts per billion) and 159 ppb. The highest measured concentration of benzene in marine water is 315 µg/l.
Environmental standards and legislation