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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(ppm) LCLo(ppm) Time Adjusted 0.5-hrLC (CF) 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 ppmBasis 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).