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Styrene (also vinyl benzene, ethenylbenzene, phenethylene, cinnamene, diarex HF 77, styrolene, styrol, styropol) is a colourless, oily, toxic, flammable organic liquid that occurs in plants, but is produced in industrial quantities from petroleum. It is used to make plastics such as polystyrene, ABS, styrene-butadiene (SBS) rubber, styrene-butadiene latex and unsaturated polyesters. It evaporates easily and has a sweet smell. It often contains other chemicals that give it a sharp, unpleasant smell.

It dissolves in some liquids but doesn't dissolve easily in water. Billions of pounds are produced each year to make products such as rubber, plastic, insulation, fiberglass, pipes, automobile parts, food containers, and carpet backing.

Most of these products contain styrene linked together in a long chain (polystyrene) as well as unlinked styrene. Low levels of styrene also occur naturally in a variety of foods such as fruits, vegetables, nuts, beverages, and meats.

Its molecular formula is C8H8, or structurally C6H5C2H3. It is synthesized by heating ethyl benzene (EB) with steam. The reversible reaction is

C6H5C2H5 → C6H5C2H3 + H2

Health effects

If you breathe high levels of styrene for a short time, you’re most likely to experience nervous system effects such as depression, concentration problems, muscle weakness, tiredness, and nausea, and possibly eye, nose, and throat irritation.

When animals breathed styrene vapors in short-term studies, they damaged the lining of their noses. Long-term exposure damaged their livers, but there is no evidence that this will occur in people because there is no information on human health effects of breathing low levels for a long time.

There is also little information on human health effects from eating or touching styrene. Animal studies show that ingestion of high levels of styrene over several weeks can cause damage to the liver, kidneys, brain, and lungs. When styrene was applied to the skin of rabbits, it caused irritation.

There is no information as to whether breathing, ingesting, or touching styrene affects fetal development or human reproduction. In animal studies, short-term exposure to very high levels resulted in some reproductive and developmental effects.

The International Agency for Research on Cancer (IARC) has determined that styrene is possibly carcinogenic to humans. Several studies of workers have shown that breathing styrene may cause leukemia. There is no information on the carcinogenicity of styrene in people who swallow it or get it on their skin. Studies in animals that breathed or ate styrene suggest that it is weakly carcinogenic.