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Benzene																				Related Pages
										May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)
**CAS number:** 71-43-2
**NIOSH REL:** 0.1 ppm TWA, 1 ppm STEL; NIOSH considers benzene to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].
**Current OSHA PEL:** 1 ppm TWA, 5 ppm STEL
**1989 OSHA PEL:** Same as current PEL
**1993-1994 ACGIH TLV:** 10 ppm (32 mg/m3) TWA, A2
**Description of substance:** Colorless to light-yellow liquid with an aromatic odor.
**LEL:** 1.2% (10% LEL, 1,200 ppm)
**Original (SCP) IDLH:** 3,000 ppm
**Basis for original (SCP) IDLH:** The chosen IDLH is based on the report in Patty [1963] that for man, a single exposure to 3,000 ppm is endurable for 0.5 to 1 hour [Flury 1928].
**Existing short-term exposure:** National Research Council [NRC 1986] guidelines
**Emergency Exposure Guidance Levels (EEGLs):****1-hour EEGL:** 50 ppm**24-hour EEGL:** 2 ppm
ACUTE TOXICITY DATA
**Lethal concentration data:**
AdjustedLC50
    LCLo
    
    0.5-hr
    DerivedSpecies
    Reference
    (ppm)
    (ppm)
    Time
    LC (CF)
    ValueRabbit
    Carpenter et al. 1944
    -----
    44,000
    30 min
    45,000 ppm (1.0)
    4,500 ppmDog
    Spector 1955
    -----
    44,923
    ?
    ?
    ?Cat
    Spector 1955
    -----
    52,308
    ?
    ?
    ?Human
    Tab Biol Per 1933
    -----
    20,000
    5 min
    11,000 ppm (0.55)
    1,100 ppm**Other human data:** It has been stated that 3,000 ppm is endurable for 0.5 to 1 hour [Flury 1928]. It has also been stated that exposure at 19,000 to 20,000 ppm for 5 to 10 minutes is fatal; exposure at 7,500 ppm for 30 minutes is dangerous; exposure at 1,500 ppm for 60 minutes induces serious symptoms; exposure at 500 ppm for 60 minutes leads to symptoms of illness; exposure at 50 to 150 ppm for 5 hours produces headache, lassitude, and weakness; and exposure at 25 ppm for 8 hours has no effect [Gerarde 1960].
 **Revised IDLH:** 500 ppm**Basis for revised IDLH:** The revised IDLH for benzene is 500 ppm based on acute inhalation toxicity data in humans [Gerarde 1960]. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for benzene at concentrations above 0.1 ppm. OSHA currently requires in 29 CFR 1910.1028 that workers be provided with and required to wear and use the "most protective" respirators in concentrations exceeding 1,000 ppm (i.e., 1,000 x the PEL).]References:
Carpenter CP, Shaffer CB, Weil CS, Smyth HF Jr [1944]. Studies on the inhalation of 1:3-butadiene; with a comparison of its narcotic effect with benzol, toluol, and styrene, and a note on the elimination of styrene by the human. J Ind Hyg Toxicol *26*(3):69-78.
Flury F [1928]. Moderne gewerbliche vergiftungen in pharmakologisch-toxikologischer hinsicht (Pharmacological-toxicological aspects of intoxicants in modern industry). Arch Exp Pathol Pharmakol *138*:65-82 (translated).
Gerarde HW [1960]. Toxicology and biochemistry of aromatic hydrocarbons. New York, NY: Elsevier Publishing Company.
NRC [1986]. Emergency and continuous exposure guidance levels for selected airborne contaminants. Vol. 6. Benzene and ethylene oxide. Washington, DC: National Academy Press, Committee on Toxicology, Board on Toxicology and Environmental Health Hazards, Commission on Life Sciences, National Research Council, pp. 7-33.
Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1221.
Spector WS, ed. [1955]. Handbook of toxicology. Vol. 1. Acute toxicities of solids, liquids and gases to laboratory animals. Philadelphia, PA: W.B. Saunders Co., p. 324.
Tab Biol Per [1933]; *3*:231 (in German).

			
							
								Page last reviewed:  December 4, 2014						Content
							source: 	National Institute for Occupational Safety and Health NIOSH Publications & Products
Immediately Dangerous To Life or Health (IDLH) Values
Table of IDLH Values
Criteria for Determining IDLH Values
Historical Documentation
Original (SCP) Values
Abbreviations for IDLH Documentation
Abbreviations for Journal Titles Follow NIOSH Facebook
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