Styrene is primarily a synthetic chemical. It is also known as vinylbenzene, ethenylbenzene, cinnamene, or phenylethylene. It's a colorless liquid that 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.

Structural diagram: National Institutes of Health

Fate & Transport

Styrene enters the environment during the manufacture, use, and disposal of styrene-based products.

It can be found in air, water, and soil.

It is quickly broken down in the air, usually within 1 to 2 days.

It evaporates from shallow soils and surface water.

It doesn't stick easily to soils and sediments.

It's broken down by bacteria in the soil and water.

It's not expected to build up in animals.

Styrene breaks down to half the amount within a few days in surface water; in groundwater, however, it takes between 6 weeks and 7.5 months.

Exposure Pathways

Breathing indoor air that is contaminated with styrene vapors from building materials, consumer products, and tobacco smoke

Breathing contaminated workplace air

Drinking contaminated water

Living near industrial facilities or hazardous waste sites

Smoking cigarettes or eating a lot of food packaged in polystyrene containers.

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 swallowing 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 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 swallowed styrene suggest that it is weakly carcinogenic.

Information excerpted from:

Toxicological Profile for Styrene 1992

Agency for Toxic Substances and Disease Registry
U.S. Dept. of Health and Human Services