Agent Name
CAS Number
Major Category
Plastics & Rubber
Styrene formula graphical representation
Cinnamene; Ethenylbenzene; Phenylethene; Phenethylene; Phenylethylene; Styrene monomer; Styrol; Styrolene; Vinylbenzene; [CHEMINFO] UN2055
Colorless to yellow, oily liquid with a sweet, floral odor; [NIOSH]
"Styrene is used extensively in the manufacture of plastics, rubber, and resins. About 90,000 workers, including those who make boats, tubs and showers, are potentially exposed to styrene." [] Used to make polystyrene for packaging, insulation for buildings and refrigeration equipment, and disposable cups and containers; Also used in styrene-butadiene rubber, other polymers, and resins to make boats, shower stalls, tires, automotive parts, etc.; [ACGIH]
Liquid causes first degree burns on short exposure; [CHRIS] There is evidence that occupational exposure to styrene in high concentrations over long periods of time can cause chronic encephalopathy similar to "Painters' syndrome" caused by other organic solvents. [Sullivan, p. 1156-7] Occupational asthma confirmed by bronchoprovocation testing in 2 workers in a plastics factory; [Malo] Styrene can induce liver injury in experimental animals. [Zimmerman, p. 367] Styrene can cause defatting of skin and CNS depression. [ICSC] A 1996-99 study of 328 reinforced plastics workers in the US found that air levels have decreased substantially over the last 10-20 years. [Reference #2] "About 95% of the amount absorbed during a 8-hour exposure can be accounted for by urinary excretion of the metabolites mandelic acid (MA) and phenylglyoxylic acid (PGA), which are produced by sequential metabolism." [ACGIH] "More recent studies by Triebig et al. (2009) and Sisto et al. (2013) suggest the threshold for styrene-induced hearing loss is likely to be between 20 and 40 ppm, expressed as mean exposure concentrations, assuming peak exposures are properly managed. Ototoxicity was only reported at concentrations >300 ppm in animals, especially in active compared to sedentary animals." [ACGIH, 2020] During the period of 1966 to 1990 the average styrene concentration in the breathing zone of open-mould workers in the European glass fibre-reinforced plastics industry has decreased on average by 5.3% per year and only 0.4% annually in the period after 1990;" [PMID 21926918] "Available evidence suggests styrene exposure is a potential risk factor for NMRD [non-malignant respiratory disease]. Additional studies of styrene-exposed workers are warranted." [PMID 28079275] Styrene monomer, stabilized (UN2055) has warning of explosive polymerization; [ERG 2016]
Reference Link #1
Biomedical References

Exposure Assessment

Mandelic acid plus phenylglyoxylic acid in urine = 400 mg/g creatinine at end of shift; Styrene in urine = 40 ug/L at end of shift; [TLVs and BEIs]
Skin Designation (ACGIH)
10 ppm
20 ppm
100 ppm, Ceiling(OSHA) = 200 ppm(600 ppm is 5-min. peak in any 3 hrs.)
20 ppm (styrene monomer)
700 ppm
Excerpts from Documentation for IDLHs
Volunteers exposed to 376 ppm for up to 7 hours experienced unpleasant subjective symptoms and objective signs of neurologic impairment [Stewart et al. 1968]. Drowsiness, nausea, headache, fatigue, and dizziness have been reported in workers exposed to 200 to 700 ppm [AIHA 1959].
Vapor Pressure
6.4 mm Hg
Odor Threshold Low
0.01 ppm
Odor Threshold High
1.9 ppm
980 ppm
Lethal Concentration
LC50 (rat) = 12,000 mg/m3/4H
Explosive Polymerization
Explanatory Notes
Detection odor threshold from AIHA (mean = 0.14 ppm); The Guide from the Emergency Response Guidebook is for "Styrene monomer, stabilized." Flash point = 34 deg C; See 2022 "Notice of Intended Changes" for BEI; [ACGIH TLVs and BEIs]
Half Life
Blood: fast phase = 0.5 hour and a slow phase = 13 hours; for mandelic acid, fast phase = 4 hours and slow = 25 hours; for phenylglyoxylic acid, urinary 1/2 life = 11 hours; [TDR, p. 1088]
may ignite at ambient temp
50 ppm
250 ppm
1,000 ppm

Adverse Effects

Acute solvent syndrome
Hepatoxic (a) from occupational exposure (secondary effect) or (b) in animal studies or in humans after ingestion
Skin burns
IARC Carcinogen
Probable (2a)
NTP Carcinogen
Anticipated human carcinogen
ACGIH Carcinogen
Confirmed Animal

Diseases, Processes, and Activities Linked to This Agent


Occupational diseases associated with exposure to this agent:


Industrial Processes with risk of exposure:


Activities with risk of exposure: