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May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

CAS number: 100–42–5

NIOSH REL: 50 ppm (215 mg/m3) TWA, 100 ppm (425 mg/m3) STEL

Current OSHA PEL: 100 ppm TWA, 200 ppm CEILING,

600 ppm 5-minute MAXIMUM PEAK IN ANY 3 HOURS

1989 OSHA PEL: 50 ppm (215 mg/m3) TWA, 100 ppm (425 mg/m3) STEL

1993-1994 ACGIH TLV: 50 ppm (213 mg/m3) TWA,

100 ppm (426 mg/m3) CEILING [skin]

Description of substance: Colorless to yellow, oily liquid with a sweet, floral odor.

LEL: . . . 0.9% (10% LEL, 900 ppm)

Original (SCP) IDLH: 5,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] that rats and guinea pigs exposed to 5,000 ppm become unconscious within 1 hour [Spencer et al. 1942].

Short-term exposure guidelines: None developed


Lethal concentration data:

Species Reference LC50




Time Adjusted 0.5-hr


Derived value
Mouse Izmerov et al. 1982 2,194 ----- 4 hr 4,388 ppm (2.0) 439 ppm
Human Lefaux 1978 ----- 10,000 30 min 10,000 ppm (1.0) 1,000 ppm
G. pig Spencer et al. 1942 ----- 2,771 14 hr 8,314 ppm (3.0) 831 ppm
Rat Tiunov et al. 1982 5,543 ----- 4 hr 11,085 ppm (2.0) 1,109 ppm

Other animal data: RD50 (mouse), 980 ppm [Alarie 1981].

Other human data: 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].

Revised IDLH: 700 ppm

Basis for revised IDLH: The revised IDLH for styrene is 700 ppm based on acute inhalation toxicity data in humans [AIHA 1959; Stewart et al. 1968].


1. AIHA [1959]. Styrene monomer. In: Hygienic guide series. Akron, OH: American Industrial Hygiene Association.

2. Alarie Y [1981]. Dose-response analysis in animal studies: prediction of human responses. Environ Health Perspect 42:9-13.

3. Izmerov NF, Sanotsky IV, Sidorov KK [1982]. Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 106.

4. Lefaux R [1978]. Practical toxicology of plastics. Cleveland, OH: Chemical Rubber Co., p. 77.

5. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1230.

6. Spencer HC, Irish DD, Adams EM, Rowe VK [1942]. The response of laboratory animals to monomeric styrene. J Ind Hyg Toxicol 24(10):295-296.

7. Stewart RD, Dodd HC, Baretta ED, Schaffer AW [1968]. Human exposure to styrene vapor. Arch Environ Health 16:656-662.

8. Tiunov LA, Zhuvov VG, et al. [1982]. Toxicity of sulfothreenaphtilenfurane. Gig Tr Prof Zabol 26(8):53-56 (in Russian).