Styrene
Styrene is a chemical primarily used in the production of various plastics, including polystyrene, styrene-acrylonitrile resin, and acrylonitrile-butadiene-styrene. While it naturally occurs in small amounts in some plants, such as coffee and strawberries, the commercial styrene is derived from petroleum and natural gas by-products. The substance has a sweet floral scent in small quantities, but can emit a harsh odor when present in larger amounts. Plastics made from styrene are valued for their lightweight, durability, and cost-effectiveness, making them integral to numerous everyday items, from food packaging to automobile parts.
However, styrene poses health risks, particularly to workers involved in its processing and production. Exposure can lead to respiratory issues and neurological symptoms, with prolonged contact resulting in more serious health conditions. Despite its widespread use, styrene's environmental impact is mitigated as it breaks down relatively quickly in air, soil, and water. The dangers of styrene are primarily associated with industrial settings, where safety measures are critical to protect workers from potential hazards. Understanding both its applications and health implications is essential for anyone engaged in industries that handle this chemical.
On this Page
Subject Terms
Styrene
Styrene is a chemical that is used in the manufacture of many types of plastics. While it occurs naturally in some plants, including some consumed as food, the styrene used in manufacturing comes from by-products of petroleum and natural gas. People depend on plastic products manufactured with styrene for everyday life, but styrene can pose a hazard to those who work with it while making or disposing of those plastic products.
Background
The chemical now known as styrene was discovered by German apothecary Eduard Simon (1789–1856). Simon was conducting experiments with the resin of a sweet gum tree called Liquidambar orientalis when he distilled a substance he called styrol. He would later discover that this substance would react with oxygen to form a polymer (a long chain of molecules) of styrol. Simon called the polymer Styroloxyd, but it would later become known as polystyrene, a type of plastic commonly used in food packing and construction.
In addition to being used to make polystyrene, styrene, the substance Simon discovered, is used to make many other forms of plastic as well. Heating causes styrene to form polymers quite easily, and styrene is used to create styrene-acrylonitrile resin (SAN), acrylonitrile-butadiene-styrene (ABS), and styrene-butadiene rubber (SBR). Styrene is also used in the manufacture of some composite plastic products, or those made with several kinds of plastic, such as fiberglass.
Overview
Styrene occurs naturally in some trees as well as in coffee, strawberries, and peanuts. The amount in these plants is small, however—much too small for commercial production. The largest sources of styrene come from the production of hydrocarbon fuels such as natural gas and crude oil. As natural gas is processed, it is run through a heating device that splits the molecules of the raw material into natural gas and other by-products, such as ethylene and benzene. Similarly, raw crude oil is processed by distillation, steam-cracking, or dehydration to extract a number of separate components, which also include benzene. The benzene and ethylene are then processed to create styrene.
The extracted and processed styrene is a clear, colorless, slightly oily liquid. It is also known by a number of other names, including vinylbenzene, vinylbenzol, ethenylbenzene, cinnamene, cinnamol, phenylethene, styrol, and styrolene. Styrene has a sweet floral scent in small quantities but a harsh, unpleasant smell in larger amounts.
The plastics manufactured with styrene are lightweight, strong, easy to clean, reasonable in cost, and durable. They have become part of nearly every facet of human life in the developed world. Styrene is in the plastics used to make household items, computer casings and components, building materials, automobile parts, and food-packing materials. Forms of styrene are used in rigid surfaces meant to protect, such as the shells of child car seats and outer casings of safety helmets. A soft, easily bent form of styrene is used to make plastic wrapping film and other, similar products. The materials made with styrene are valued for their versatility and relative cost-effectiveness. In some cases, no substitute exists for items made of styrene-based plastic; for example, it would be difficult for supermarkets to sell meat without disposable plastic trays and wrap that allow for hygienic packaging and display. When substitutes are available, styrene-based plastics generally provide an advantage in product costs, labor costs, or both.
Health Concerns
Styrene makes its way into the environment during the manufacturing process as well as during the processes that break down and dispose of manufactured plastic products. It can be found in air, soil, and water near processing facilities. However, styrene in the air breaks down in twenty-four to forty-eight hours and is generally diluted enough not to be a threat. It also evaporates quickly when in soil or water; any residual is readily broken down by microorganisms in the soil or water.
In general, the styrene in manufactured items poses little threat to the consumer. There is a slight chance of residual styrene being on a manufactured item, as well as a risk that some styrene could be released if a plastic item is burned. Styrene is also released in small amounts in the emissions from motor vehicles and cigarettes. The quantities present in these circumstances are nearly always too slight to pose a health risk.
The danger from styrene comes to those who work with the chemical directly in places where it is processed from natural gas or crude oil by-products or where it is used in the manufacture of plastics. Here, a person can be exposed to large enough quantities for long enough periods of time to experience health risks.
The most common problems with styrene exposure result from inhaling the fumes or having the chemical come into contact with the skin or eyes. Inhalation of styrene fumes can irritate the throat and nose, causing coughing, wheezing, and other respiratory symptoms. With prolonged inhalation exposure, the person can experience a condition known as styrene sickness. Someone with this condition appears drunk and exhibits signs of clumsiness, dizziness, and confusion. The individual might also feel weak and suffer from headaches, tiredness, nausea, and vomiting. This is because styrene works on the nervous system to cause what is known as central nervous system depression. If a person continues to inhale styrene fumes, he or she can experience an irregular heartbeat, lung congestion, and possibly a coma. Fortunately, the unpleasant smell generated by anything more than a small amount of styrene provides a warning for people to leave the area and avoid the more severe effects of styrene inhalation.
Coming into physical contact with liquid styrene can cause irritation to skin and eyes. This can be mild—itching, redness, peeling or flaking skin—or as severe as a first-degree burn. This irritation generally goes away when exposure is discontinued; however, repeated exposure once skin has been affected by contact allows more of the chemical to penetrate the skin and can cause more severe effects. Long-term exposure can cause brain disease, damage to the liver, kidney, and nerves, occupational asthma, impaired hearing, altered color vision, and reproductive system problems. Styrene has also been classified as a possible carcinogen, or cancer-causing agent.
Bibliography
"Polystyrene." Plastics Europe, PERLINK "http://www.plasticseurope.org/what-is-plastic/types-of-plastics-11148/polystyrene.aspx" http://www.plasticseurope.org/what-is-plastic/types-of-plastics-11148/polystyrene.aspx. Accessed 31 Oct. 2016.
Sadighara, Parisa, et. al. "The Amount and Detection Method of Styrene in Foods: A Systematic Review and Meta-Analysis." Food Chemistry: X, vol. 13, no. 20, Mar. 2022, doi.org/10.1016/j.fochx.2022.100238. Accessed 1 Jan. 2023.
"Styrene." United States Department of Labor, HYPERLINK "https://www.osha.gov/SLTC/styrene/index.html" https://www.osha.gov/SLTC/styrene/index.html. Accessed 31 Oct. 2016.
"Styrene." Tox Town. US National Library of Medicine, chemicals.php?id=87" https://toxtown.nlm.nih.gov/text‗version/chemicals.php?id=87. Accessed 31 Oct. 2016.
"Styrene." California Department of Health, May 1990. cuments/styrene.pdf" https://www.cdph.ca.gov/programs/hesis/Documents/styrene.pdf. Accessed 31 Oct. 2016.
"Styrene: A Building Block for Essential Products." SRIC (Styrene Information & Research Center), HYPERLINK "http://styrene.org/wp-content/uploads/2013/11/styrene-brochure2013.pdf" http://styrene.org/wp-content/uploads/2013/11/styrene-brochure2013.pdf. Accessed 31 Oct. 2016.
"Toxic Substances Portal – Styrene." US Centers for Disease Control Agency for Toxic Substances and Disease Registry, June 2012. HYPERLINK "http://www.atsdr.cdc.gov/PHS/PHS.asp?id=419&tid=74" http://www.atsdr.cdc.gov/PHS/PHS.asp?id=419&tid=74. Accessed 31 Oct. 2016.
Wakefield, J.C. "Styrene General Information." Health Protection Agency, 2007. HYPERLINK "https://www.gov.uk/government/uploads/system/uploads/attachment‗data/file/338266/HPA‗STYRENE‗General‗Information‗v1.pdf" https://www.gov.uk/government/uploads/system/uploads/attachment‗data/file/338266/HPA‗STYRENE‗General‗Information‗v1.pdf. Accessed 31 Oct. 2016.