Agent Name

Benzene

CAS Number

71-43-2

Formula

C6-H6

Major Category

Solvents

Synonyms

(6)Annulene; Benzene; Benzin; Benzine; Benzol; Benzol 90; Benzole; Benzolene; Bicarburet of hydrogen; Carbon oil; Coal naphtha; Cyclohexatriene; Mineral naphtha; Motor benzol; Nitration benzene; Phene; Phenyl hydride; Polystream; Pyrobenzol; Pyrobenzole; [ChemIDplus] UN1114

Category

Aromatic Solvents

Description

Colorless to light-yellow liquid with an aromatic odor. Note: A solid below 42 degrees F; [NIOSH]

Sources/Uses

Benzene was used in the past as a solvent in inks, rubber, lacquers, and paint removers. Today, it is used mainly in closed processes to synthesize organic chemicals. Gasoline in some countries contains a high concentration of benzene (as high as 30%); the U.S. average is 1-3%. Workers who remove or clean underground storage tanks may be exposed to significant levels. [ACGIH] Gasoline in North America now contains about 1% benzene. [AIHAJ 2002;63(2):225-30]

Comments

"The final OSHA Benzene standard in 1910.1028 applies to all occupational exposures to benzene except some subsegments of industry where exposures are consistently under the action level (i.e., distribution and sales of fuels, sealed containers and pipelines, coke production, oil and gas drilling and production, natural gas processing, and the percentage exclusion for liquid mixtures);" [NIOSH Pocket Guide Appendix] As an organic solvent, benzene can induce narcosis and anesthesia acutely. After chronic exposure, it can cause aplastic anemia and leukemia. [ACGIH] Significant benzene exposure increases the risk of leukemia during the 10 years following exposure. Risk is not related to exposures that occurred greater than 20 years prior to the onset of disease. [Am J Ind Med 2000;38(1):1-7] The highest exposures (mean of 11 ppm) in petroleum refinery workers occur in disconnecting cargo loading hoses, and respiratory protection is required. [PMID 20941467] Workers exposed to products containing <0.1% benzene are not likely to be exposed above the TLV of 0.5 ppm. [PMID 18615290] In high-dose animal reproductive studies, benzene increases sperm abnormalities, fetal loss, and delayed ossification. [Frazier]

Restricted

EPA restricts benzene emission from specific point sources; maximum contaminant level in drinking water is 5 ppb; FDA prohibits the use of benzene in food; [ATSDR Case Studies]

Reference Link

OSHA Technical Links: Benzene

Exposure Assessment
BEI

S-phenylmercapturic acid in urine = 25 ug/g creatinine; t,t-Muconic acid in urine = 500 ug/g creatinine; sample at end of shift;

Skin Designation (ACGIH)

Yes

STEL (ACGIH)

2.5 ppm

PEL (OSHA)

1 mg/m3, STEL(OSHA) = 5 ppm (see CFR 1910.1028)

Excerpts from Documentation for IDLHs

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].

Vapor Pressure

94.8 mm Hg

Odor Threshold Low

34 ppm

Odor Threshold High

119 ppm

Lethal Concentration

LC50 (rat) = 10,000 ppm/7h

Explanatory Notes

Detection odor thresholds from AIHA; Flash point = 12 deg F;

Half Life

Whole body: 9-24 hours; however, up to 90 hours due to distribution in fat; [TDR, p. 154]

Reference Link

ATSDR Medical Management - Benzene

Flammability (NFPA)

3: May ignite at ambient temperature

Adverse Effects
Reproductive Toxin

Yes

Neurotoxin

CNS Solvent Syndrome

Anemia

Anemia, Aplastic

IARC Carcinogen

Known Carcinogen

NTP Carcinogen

Human Carcinogen

ACGIH Carcinogen

Confirmed Human

Links to Other NLM Databases
Health Studies

Human Health Effects from Hazardous Substances Data Bank:

Toxicity Information

Chemical Information

Search ChemIDplus

Biomedical References

Search PubMed

Related Information in HazMap
Diseases

Occupational diseases associated with exposure to this agent:

Processes

Industrial Processes with risk of exposure:

Activities

Activities with risk of exposure: