2023-03-03

Styrene, also known as ethenylbenzene, vinylbenzene, and phenylethene, is an organic compound with the molecular formula C8H8.[1]

Pure styrene is a colourless to yellowish oily liquid that evaporates easily and has a sweet smell. It is often mixed with other substances that give it a sharp smell. It is flammable. [2]

Uses [2]

When it is linked together in long chains, or polymerised, styrene is used predominantly in the production of polystyrene plastics and resins, such as in insulation or in the fabrication of fibreglass boats; most styrene products contain a residue of unlinked styrene. Styrene is also used to make rubber, and as an intermediate in the synthesis of materials used for ion exchange resins and to produce copolymers such as styrene-acrylonitrile, acrylonitrile-butadiene-styrene, and styrene-butadiene rubber.

Sources & Routes of Exposure

Sources of Emission [2]

Industry sources: Styrene will be emitted to air from industrial process that use or manufacture the material or where it is formed as a by-product.
Diffuse sources: Styrene is present in combustion products such as cigarette smoke.
Natural sources: Low levels of styrene occur naturally in a variety of foods, such as fruits, vegetables, nuts, beverages, and meats.
Transport sources: Styrene is present in car exhaust.
Consumer products: Products produced from styrene include packaging, electrical and thermal insulation, fibreglass, pipes, car parts, drinking cups and other food-use items, and carpet backing.

Routes of Exposure [3]

The routes of exposure to styrene are through:

inhalation,
skin absorption,
ingestion,
skin and/or eye contact

In the Environment [4]

Styrene can be found in air, water, and soil after release from the manufacture, use, and disposal of styrene-based products.
It is quickly broken down in the air, usually within 1 to 2 days.
Styrene evaporates from shallow soils and surface water.
Styrene that remains in soil or water may be broken down by bacteria or other microorganisms.
Styrene is not expected to build up in animals.

Health Effect [5]

Acute Effects

Acute exposure to styrene in humans results in respiratory effects, such as mucous membrane irritation, eye irritation, and gastrointestinal effects.
Tests involving acute exposure of rats and mice have shown styrene to have low to moderate toxicity by inhalation and oral exposure.

Chronic Effects

Chronic exposure to styrene in humans results in effects on the central nervous system (CNS), with symptoms such as headache, fatigue, weakness, depression, CNS dysfunction (reaction time, memory, visuomotor speed and accuracy, intellectual function), and hearing loss, peripheral neuropathy, minor effects on some kidney enzyme functions and on the blood.
Animal studies have reported effects on the CNS, liver, kidney, and eye and nasal irritation from inhalation exposure to styrene.
Liver, blood, kidney, and stomach effects have been observed in animals following chronic oral exposure.
The Reference Concentration (RfC) for styrene is 1 milligram per cubic metre (mg/m3) based on CNS effects in occupationally exposed workers.
The Reference Dose (RfD) for styrene is 0.2 milligrams per kilogram body weight per day (mg/kg/d) based on red blood cell and liver effects in dogs.

Reproductive/Developmental Effects

Human studies have not reported an increase in developmental effects in women who worked in the plastics industry, while an increased frequency of spontaneous abortions and a decreased frequency of births were reported in a study on the reproductive effects of styrene in humans. However, these studies are not conclusive, due to the lack of exposure data and confounding factors.
Animal studies have not reported developmental or reproductive effects from inhalation exposure to styrene.
Lung tumours have been observed in the offspring of orally exposed mice.

Cancer Risk

Several epidemiologic studies suggest that there may be an association between styrene exposure and an increased risk of leukaemia and lymphoma. However, the evidence is inconclusive due to multiple chemical exposures and inadequate information on the levels and duration of exposure.
Animal cancer studies have produced variable results and provide limited evidence for carcinogenicity.
IARC has classified styrene as a Group 2B, possibly carcinogenic to humans.
Styrene oxide is a reactive metabolite of styrene and shows positive carcinogenic results in oral exposure bioassays. Styrene oxide has been detected in workers exposed to styrene. IARC has classified this metabolite as a Group 2A, probable human carcinogen.
EPA does not have a carcinogen classification for styrene; the chemical currently is undergoing an EPA Integrated Risk Information System (IRIS) review to establish such a classification.

Safety [6]

First Aid Measures

Eye Contact: Check for and remove any contact lenses. Immediately flush eyes with running water for at least 15 minutes, keeping eyelids open. Cold water may be used. Do not use an eye ointment. Seek medical attention.
Skin Contact: After contact with skin, wash immediately with plenty of water. Gently and thoroughly wash the contaminated skin with running water and non-abrasive soap. Be particularly careful to clean folds, crevices, creases and groin. Cover the irritated skin with an emollient. If irritation persists, seek medical attention. Wash contaminated clothing before reusing.
Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek immediate medical attention.
Inhalation: Allow the victim to rest in a well-ventilated area. Seek immediate medical attention.
Ingestion: Do not induce vomiting. Examine the lips and mouth to ascertain whether the tissues are damaged, a possible indication that the toxic material was ingested; the absence of such signs, however, is not conclusive. Loosen tight clothing such as a collar, tie, belt or waistband. If the victim is not breathing, perform mouth-to-mouth resuscitation. Seek immediate medical attention.

Fires & Explosion Information

Styrene is flammable.
Auto-ignition temperature is 490°C (914°F)
Flash Points: closed cup is 31.1°C (88°F) and open cup is 36.7°C (98.1°F).
Styrene is flammable in the presence of open flames and sparks and slightly flammable to flammable in the presence of heat.
Dry chemical powder should be used to extinguish small fires.
Alcohol foam, water spray or fog should be used to extinguish large fires.
Cool containing vessels with water jet in order to prevent pressure build-up, autoignition or explosion.

Exposure Controls & Personal Protection

Engineering Controls

The following engineering controls should be provided when handling styrene:

Exhaust ventilation or other engineering controls to keep the airborne concentrations of vapours below their respective threshold limit value.
Ensure that eyewash stations and safety showers are proximal to the work-station location.

Personal Protective Equipment

The following personal protective equipment should be used when handling styrene:

Splash goggles;
Lab coat;
Vapour respirator (be sure to use an approved/certified respirator or equivalent);
Gloves.

Personal Protective Equipment in Case of a Large Spill:

Splash goggles;
Full suit;
Vapour respirator;
Boots;
Gloves;
A self contained breathing apparatus should be used to avoid inhalation of the product.
Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this product.

Regulation

United States [7]

Exposure Limit	Limit Values	HE Codes	Health Factors and Target Organs
OSHA Permissible Exposure Limit(PEL): General Industry	100ppm TWA 200ppm Ceiling Exception to ceiling value: 600 ppm (peak), for a single time period up to 5 minutes for any 3 hours	HE7	Central nervous system depression
		HE11	Irritation of the lungs
		HE15	Eye, nose, and skin irritation
OSHA PEL: Construction Industry	100ppm (420 mg/m³) Ceiling	HE7	Central nervous system depression
		HE11	Irritation of the lungs
		HE15	Eye, nose, and skin irritation
OSHA PEL: Shipyard Employment	100ppm (420 mg/m³) TWA	HE7	Central nervous system depression
		HE11	Irritation of the lungs
		HE15	Eye, nose, and skin irritation
National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)	50ppm (215 mg/m³) TWA 100ppm (425 mg/m³) STEL	HE2	Mutagenic effects, including cytogenic changes
		HE7	Central nervous system depression
		HE8	Narcosis
		HE15	Eye, nose, throat, and skin irritation
American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV)	20ppm TWA 40ppm STEL A4;BEI	HE2	Chromosomal abnormalities in peripheral lymphocytes
		HE7	Central nervous system depression; peripheral nervous system impairment; optic and otoneurologic impairment
		HE15	Irritation of eyes, mucous membranes, upper respiratory system, and skin
CAL/OSHA PELs	50ppm (215 mg/m³) TWA 500ppm Ceiling 100ppm (425 mg/m³) STEL Skin

Australia [2]

Safe Work Australia: Safe Work Australia has established an eight hour time weighted average (TWA) exposure limit for styrene of 50 ppm (213 mg/m3) and a short term exposure limit (STEL) of 100 ppm (426 mg/m3)

Australian Drinking Water Guidelines (NHMRC and ARMCANZ, 1996):

Health: Maximum of 0.03 mg/L (i.e. 0.00003 g/L)
Aesthetic: Maximum of 0.004 mg/L (i.e. 0.000004 g/L)

References

http://en.wikipedia.org/wiki/Styrene

http://www.npi.gov.au/resource/styrene-ethenylbenzene

http://www.cdc.gov/niosh/npg/npgd0571.html

http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=420&tid=74

http://www.epa.gov/ttn/atw/hlthef/styrene.html

http://www.sciencelab.com/msds.php?msdsId=9925112

https://www.osha.gov/dts/chemicalsampling/data/CH_268200.html