LABORATORY CHEMICAL SAFETY SUMMARY: BENZENE

Substance

Benzene

(Benzol)

CAS 71-43-2

 

Formula

C6H6

 

Physical Properties

Colorless liquid

bp 80.1 °C, mp 5.5 °C

Slightly soluble in water (0.18 g/100 mL)

 

Odor

"Paint-thinner-like" odor detectable at 12 ppm

Vapor Density

2.7 (air = 1.0)

 

Vapor Pressure

75 mmHg at 20 °C

 

Flash Point

-11.1 °C

 

Autoignition Temperature

560 °C

 

Toxicity Data

LD50 oral (rat)

930 mg/kg

 

LC50 inhal (rat)

10,000 ppm (7 h)

 

PEL (OSHA)

1 ppm (3.2 mg/m3)

 

TLV-TWA (ACGIH)

10 ppm (32 mg/m3)

 

STEL (ACGIH)

5 ppm (16 mg/m3)

Major Hazards

Highly flammable; chronic toxin affecting the blood-forming organs; OSHA "select carcinogen."

Toxicity

The acute toxicity of benzene is low. Inhalation of benzene can cause dizziness, euphoria, giddiness, headache, nausea, drowsiness, and weakness. Benzene can cause moderate irritation to skin and severe irritation to eyes and mucous membranes. Benzene readily penetrates the skin to cause the same toxic effects as inhalation or ingestion.

The chronic toxicity of benzene is significant. Exposure to benzene affects the blood and blood-forming organs such as the bone marrow, causing irreversible injury; blood disorders including anemia and leukemia may result. The symptoms of chronic benzene exposure may include fatigue, nervousness, irritability, blurred vision, and labored breathing. Benzene is regulated by OSHA as a carcinogen (Standard 1910.1028) and is listed in IARC Group 1 ("carcinogenic to humans"). This substance is classified as a "select carcinogen" under the criteria of the OSHA Laboratory Standard.

Flammability and Explosibility

Benzene is a highly flammable liquid (NFPA rating = 3), and its vapors may travel a considerable distance to a source of ignition and "flash back." Vapor-air mixtures are



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