Alessandro Moretti
Alessandro MorettiPh.D.Italy
Laser-Based Additive Manufacturing
Published
Dec 24, 2025

Benzene (C₆H₆)

Chemical Properties

Chemical Identity

CAS Number
71-43-2
Formula
C₆H₆
Molecular Weight
78.11 g/mol

Exposure Limits Comparison

OSHA PEL
1 ppm
NIOSH REL
0.1 ppm
ACGIH TLV
0.5 ppm

Health Effects

Leukemia
Yes
Bone Marrow Damage
Yes
Blood Disorders
Yes
Dizziness
Yes
Drowsiness
Yes

Benzene (C₆H₆) safety information

Comprehensive safety and handling requirements

Detection Monitoring
Sensor Types
  • Photoionization detector (PID)
  • Infrared
  • Flame ionization detector (FID)
  • Colorimetric tubes
Detection Range0-10 ppm typical, 0-100 ppm extended
Alarm Setpoints
Low1 ppm (OSHA PEL)
High5 ppm (OSHA STEL)
Evacuate500 ppm (NIOSH IDLH)
Colorimetric Tubes
  • Dräger CH25801
  • Gastec 121
  • Kitagawa 118
Analytical Methods
MethodTechniqueDetection Limit
NIOSH 1501GC-FID (Gas Chromatography - Flame Ionization)0.01 ppm
OSHA 12GC-FID with charcoal tube0.01 ppm
Odor ThresholdNOT reliable indicator. Odor threshold (1.5-4.7 ppm) is above safe exposure levels and varies greatly. Do not rely on odor - use monitoring equipment.
Environmental Impact
Aquatic ToxicityToxic to aquatic organisms. LC50 (fish, 96h): 5.3-5.9 mg/L (rainbow trout). Toxic to algae and invertebrates.
BiodegradabilityReadily biodegradable under aerobic conditions. >60% degradation in 28 days.
BioaccumulationLow potential. Log Kow: 2.13 (does not bioaccumulate significantly)
Soil MobilityHigh mobility. Low soil adsorption. May leach to groundwater.
Atmospheric FatePhotooxidation half-life: 4-17 days. Reacts with hydroxyl radicals. Does not undergo direct photolysis.
Ozone Depletionfalse
Reportable Releases
Water10 lbs (4.54 kg) to navigable waters (CWA Section 311)
Air10 lbs/day (CERCLA RQ)
Ppe Requirements
RespiratoryNIOSH-approved organic vapor respirator with full facepiece for >10 ppm, SCBA or supplied-air for >50 ppm or unknown concentrations
Eye ProtectionChemical safety goggles and face shield for splash potential
Skin ProtectionNitrile gloves (>0.5mm), butyl rubber gloves, chemical-resistant clothing, impervious suit for spill response
Reactivity
StabilityStable under normal conditions. May polymerize with aluminum chloride catalyst.
PolymerizationWill not occur under normal conditions.
Incompatible Materials
  • Strong oxidizers
  • Halogens
  • Nitric acid
  • Sulfuric acid
  • Perchlorates
  • Permanganates
  • Peroxides
  • Aluminum chloride (catalyst)
Hazardous Decomposition
  • Carbon monoxide
  • Carbon dioxide
  • Irritating and toxic fumes
Conditions To Avoid
  • Heat
  • Flames
  • Sparks
  • Static discharge
  • Oxidizers
  • High temperatures
Reactivity HazardReacts violently with strong oxidizers causing fire and explosion hazard. Attacks some forms of plastics, rubber, and coatings.
Regulatory Classification
Un NumberUN1114
Dot Hazard Class3 (Flammable liquid)
Dot LabelFlammable Liquid
Nfpa Codes
Health2
Flammability3
Reactivity0
Epa Hazard Categories
  • Acute toxicity
  • Flammability
  • Carcinogenicity
  • Germ cell mutagenicity
  • Reproductive toxicity
  • Specific target organ toxicity (repeated exposure)
  • Aspiration hazard
Sara Title Iiitrue
Cercla Rq10 pounds (4.54 kg)
Rcra CodeU019
Storage Requirements
Temperature RangeStore below 25°C (77°F) in cool area
VentilationLocal exhaust ventilation required, explosion-proof equipment, minimum 100 ft/min face velocity
Incompatibilities
  • Strong oxidizers
  • Halogens (chlorine, bromine)
  • Nitric acid
  • Sulfuric acid
  • Perchlorates
  • Permanganates
  • Peroxides
Container MaterialSteel, stainless steel, or aluminum containers. Avoid plastics that dissolve in benzene.
SegregationSeparate from oxidizers, acids, halogens. Store in approved flammable liquid storage cabinet. Keep away from heat, sparks, open flames.
Quantity LimitsFlammable liquid storage per 29 CFR 1910.106: Maximum 10 gallons outside approved cabinet, 60 gallons inside safety cabinet
Special RequirementsStore in tightly sealed containers in cool, dry, well-ventilated area. Ground and bond containers during transfer. Use explosion-proof electrical equipment.

Produced From Contaminants

Z-Beam Logo
Z-Beam Logo
Z-Beam Logo
Z-Beam Logo
Z-Beam Logo

Exposure Limits

Regulatory exposure thresholds and safe concentration levels

Osha Pel Ppm
1
Osha Pel Mg M3
3.2
Niosh Rel Ppm
0.1
Niosh Rel Mg M3
0.32
Acgih Tlv Ppm
0.5
Acgih Tlv Mg M3
1.6
Workplace Exposure
Osha Pel
twa_8hr: 1 ppm
stel_15min: 5 ppm
ceiling: null
Niosh Rel
twa_8hr: 0.1 ppm
stel_15min: 1 ppm
ceiling: null
idlh: 500 ppm
Acgih Tlv
twa_8hr: 0.5 ppm
stel_15min: 2.5 ppm
ceiling: null
Biological Exposure Indices
0: [object Object]
1: [object Object]

Physical Properties

Physical characteristics and state information

Boiling Point
80.1°C (176°F)
Melting Point
5.5°C (42°F)
Vapor Pressure
95 mmHg @ 25°C
Vapor Density
2.77 (Air=1)
Specific Gravity
0.8765 @ 20°C
Flash Point
-11°C (12°F) closed cup
Autoignition Temp
498°C (928°F)
Explosive Limits
LEL: 1.2%, UEL: 7.8%
Appearance
Clear, colorless to pale yellow liquid
Odor
Sweet, aromatic odor; Odor threshold: 1.5-4.7 ppm (variable, not reliable)

Reactivity

Chemical reactivity and compatibility with other substances

Stability
Stable under normal conditions. May polymerize with aluminum chloride catalyst.
Polymerization
Will not occur under normal conditions.
Incompatible Materials
  • Strong oxidizers
  • Halogens
  • Nitric acid
  • Sulfuric acid
  • Perchlorates
  • Permanganates
  • Peroxides
  • Aluminum chloride (catalyst)
Hazardous Decomposition
  • Carbon monoxide
  • Carbon dioxide
  • Irritating and toxic fumes
Conditions To Avoid
  • Heat
  • Flames
  • Sparks
  • Static discharge
  • Oxidizers
  • High temperatures
Reactivity Hazard
Reacts violently with strong oxidizers causing fire and explosion hazard. Attacks some forms of plastics, rubber, and coatings.

Synonyms & Identifiers

Alternative names and chemical identifiers (CAS numbers)

Synonyms
  • Benzol
  • Benzole
  • Phenyl hydride
  • Cyclohexatriene
  • Pyrobenzol
  • Coal naphtha
  • Mineral naphtha
Common Trade Names
  • Benzol
  • Motor benzol
Other Identifiers
Rtecs Number
CY1400000
Ec Number
200-753-7
Pubchem Cid
241