Xylene

Classification

Flammable liquid, Category 3; Acute toxicity (inhalation and dermal), Category 4; Skin irritation, Category 2; Eye irritation, Category 2A; STOT single exposure, Category 3 (respiratory irritation); STOT repeated exposure, Category 2 (hearing organs, central nervous system, liver, kidneys); Aspiration hazard, Category 1. Exact classifications vary slightly between suppliers, so check your safety data sheet.

Hazard statements

• H226 Flammable liquid and vapor.
• H304 May be fatal if swallowed and enters airways.
• H312+H332 Harmful in contact with skin or if inhaled.
• H315 Causes skin irritation.
• H319 Causes serious eye irritation.
• H335 May cause respiratory irritation.
• H373 May cause damage to organs (hearing organs, nervous system, liver, kidneys) through prolonged or repeated exposure.

Key precautionary statements

• P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
• P240 Ground and bond container and receiving equipment.
• P241 Use explosion-proof electrical, ventilating and lighting equipment.
• P260 Do not breathe vapors.
• P280 Wear protective gloves, protective clothing, eye protection and face protection.
• P301+P310 IF SWALLOWED: Immediately call a POISON CENTER or doctor.
• P331 Do NOT induce vomiting.
• P403+P235 Store in a well-ventilated place. Keep cool.

The OSHA permissible exposure limit for xylene (all isomers) is 100 ppm as an 8-hour TWA, from Table Z-1. NIOSH recommends 100 ppm TWA with a 150 ppm STEL. The ACGIH TLV is much lower at 20 ppm TWA, and ACGIH flags xylene as an ototoxicant, meaning it can add to noise-related hearing loss. Cal/OSHA sets 100 ppm TWA, a 150 ppm STEL and a 300 ppm ceiling. The NIOSH IDLH is 900 ppm. Xylene can also be absorbed through the skin, so air limits alone do not capture total exposure. State OSHA plans may set different limits.

• Appearance: Colorless liquid
• Odor: Sweet, aromatic odor
• Molecular weight: 106.2
• Boiling point: About 281°F (138°C); isomers range roughly 270–292°F
• Flash point: 77–90°F (25–32°C) depending on grade and isomer mix, Class IC flammable liquid
• Explosive limits: LEL 0.9–1.1%, UEL 6.7–7.0%
• Vapor pressure: 7–9 mmHg
• Vapor density: 3.7 (air = 1); vapors are heavier than air
• Specific gravity: 0.86–0.88 (floats on water)
• Water solubility: Very slight (about 0.02%)

Inhalation

Irritates the nose, throat and lungs. Vapors cause headache, dizziness, nausea, poor coordination and drowsiness; very high levels can lead to unconsciousness and death. See xylene exposure for more on how workers are typically exposed.

Skin

Irritates the skin and strips its natural oils, so repeated contact causes dryness, redness and occupational dermatitis. Xylene is absorbed through the skin and adds to the total dose.

Eyes

Causes eye irritation. High vapor exposure has been linked to changes in the cornea.

Ingestion

Causes nausea, vomiting and stomach pain. The bigger danger is aspiration: if the liquid is breathed into the lungs it can cause severe, possibly fatal, chemical pneumonia. Do not induce vomiting.

Target organs

Eyes, skin, respiratory system, central nervous system, gastrointestinal tract, blood, liver, kidneys

Long-term effects

Repeated exposure can affect memory, concentration, vision and coordination, and may damage the liver and kidneys. Xylene is one of the recognized ototoxic chemicals, so combined solvent and noise exposure deserves extra attention. The NJ Department of Health notes it may harm the developing fetus. Xylene is not classifiable as a human carcinogen (IARC Group 3). Like other organic solvents, its nervous system effects resemble those of toluene.

Gloves

The New Jersey Department of Health lists Viton, Viton/Butyl, polyvinyl alcohol (PVA), Silver Shield/4H and Barrier gloves. One supplier SDS reports more than 8 hours of breakthrough time for 0.7 mm fluorinated rubber (Viton) gloves, while thicker nitrile is suitable only for splash contact. PVA gloves break down in water. See hand protection for selection tips.

Eyes and face

Chemical splash goggles; add a face shield for large transfers.

Respiratory

Control vapors with local exhaust ventilation first. Above exposure limits, NIOSH lists air-purifying respirators with organic vapor cartridges up to 900 ppm. Use a pressure-demand SCBA for emergencies, unknown concentrations or anything at or above the IDLH, all within a written respiratory protection program.

Clothing

Chemical-resistant clothing such as Tychem BR, CSM or TK where splashing is likely. Remove clothing promptly if wet, because it is flammable, and wash skin when contaminated.

Store in tightly closed containers in a flammable-liquid cabinet or approved flammables area that is cool and well ventilated, away from heat, sparks and flame.

Ground and bond metal containers during transfer, use non-sparking tools and explosion-proof equipment, and guard against static discharge, since pouring and agitation can build up a charge. Use only with adequate ventilation.

Keep away from

• Strong oxidizers (such as peroxides, nitrates, perchlorates, permanganates, chlorine and fluorine)
• Strong acids (such as nitric acid, sulfuric acid and hydrochloric acid)

• Eliminate all ignition sources and ventilate the area.
• Evacuate unprotected people and control entry; vapors are heavier than air and can travel to distant ignition sources.
• Use spark-proof tools and explosion-proof equipment.
• Absorb with dry sand, earth, vermiculite or another inert material and place in sealed containers for disposal.
• Keep out of drains, sewers and confined spaces.
• Waste may need to be handled as hazardous waste; check with your state environmental agency or EPA.
• For larger spills, refer to ERG Guide 130.

Suitable extinguishing media

• Dry chemical
• Carbon dioxide (CO₂)
• Foam (alcohol-resistant foam is commonly recommended)
• Water spray to cool fire-exposed containers (a water stream may spread the fire)

Special hazards

Flammable. Vapors are heavier than air, can travel to an ignition source and flash back, and can form explosive mixtures inside closed tanks. Containers may explode when heated. Fires produce carbon monoxide and carbon dioxide. Firefighters should wear SCBA and full protective gear.

• OSHA Hazard Communication (29 CFR 1910.1200): Hazardous chemical; labels, safety data sheets and worker training required.
• OSHA Flammable Liquids (29 CFR 1910.106): Class IC flammable liquid.
• OSHA Air Contaminants (29 CFR 1910.1000 Table Z-1): 100 ppm TWA.
• CERCLA hazardous substance (40 CFR 302.4): Listed as "Benzene, dimethyl-" (xylene, mixed); reportable quantity 100 lb (45.4 kg). RCRA waste code U239.
• DOT Hazardous Materials (49 CFR 172.101): UN1307 Xylenes, Class 3; packing group depends on flash point (common commercial grades ship as PG III).

• NIOSH Pocket Guide: o-Xylene
• OSHA Occupational Chemical Database: Xylene, all isomers
• NJ Department of Health Hazardous Substance Fact Sheet: Xylenes
• Sigma-Aldrich SDS: Xylenes (534056)
• 40 CFR 302.4: CERCLA hazardous substances and reportable quantities