Xylene is a colorless, flammable liquid solvent with a sweet, aromatic odor. It is widely used in paints, coatings, adhesives, cleaning products, printing, laboratories and the chemical industry. Workers can be exposed by breathing its vapor, through skin contact and absorption, and less commonly by swallowing it.
Xylene evaporates quickly, so vapor builds up easily in poorly ventilated spaces. High exposures affect the central nervous system, and liquid xylene irritates the skin and eyes. OSHA and NIOSH set exposure limits, and xylene is covered by OSHA's Hazard Communication Standard.
What Is Xylene?
Xylene, also called dimethylbenzene or xylol, exists in three forms called isomers: ortho-xylene (o-xylene), meta-xylene (m-xylene) and para-xylene (p-xylene). According to ATSDR, commercial or mixed xylene is usually a mixture of these isomers and often contains 10 to 50 percent ethylbenzene.
Xylene is made mainly from petroleum. It is used as a solvent, as a thinner for paints and coatings, in glues and pesticides, and as a raw material for making other chemicals. Xylene is also present in gasoline and in vehicle exhaust.
Health Effects of Xylene
The NIOSH Pocket Guide to Chemical Hazards lists the following for xylene:
- Exposure routes: inhalation, skin absorption, ingestion, and skin or eye contact.
- Symptoms: irritation of the eyes, skin, nose and throat; dizziness, excitement, drowsiness, incoordination and staggering gait; corneal vacuolization; loss of appetite, nausea, vomiting and abdominal pain; and dermatitis.
- Target organs: eyes, skin, respiratory system, central nervous system, gastrointestinal tract, blood, liver and kidneys.
ATSDR notes that breathing high levels of xylene for a short time can cause headaches, dizziness and impaired reaction time, memory and vision. Animal studies have shown respiratory and neurological effects, including hearing loss. Repeated skin contact can remove natural oils from the skin and cause dermatitis.
On cancer, ATSDR reports that EPA found the available data inadequate to assess whether xylene causes cancer, and that the International Agency for Research on Cancer (IARC) considers xylene not classifiable as to its carcinogenicity to humans.
Exposure Limits for Xylene
- OSHA PEL: 100 ppm (435 mg/m³) as an 8-hour time-weighted average (TWA).
- NIOSH REL: 100 ppm (435 mg/m³) TWA and a short-term exposure limit (STEL) of 150 ppm (655 mg/m³).
- NIOSH IDLH: 900 ppm, the level NIOSH considers immediately dangerous to life or health.
These values are from the NIOSH Pocket Guide entry for o-xylene; check the entries for the other isomers and your product's SDS. OSHA's PEL is legally enforceable. The NIOSH REL is a recommendation, but many employers use it, along with the STEL, as a better measure of short, high exposures such as those during spray painting, tank cleaning or spill response.
Fire and Physical Hazards
Xylene is a flammable liquid. NIOSH lists the flash point of o-xylene as 90°F, which means flammable vapor can form at temperatures found in many workplaces. Vapors are heavier than air and can travel along floors to an ignition source. Store xylene in approved containers and cabinets, bond and ground containers during transfer (see bonding and grounding), and control ignition sources, including through a hot work permit program.
Regulatory Requirements
Hazard Communication
Xylene and xylene-containing products are hazardous chemicals under OSHA's Hazard Communication Standard, 29 CFR 1910.1200. Employers must keep a safety data sheet for each product, ensure containers are labeled according to the Globally Harmonized System, and train workers on the hazards and protective measures before they are exposed.
Air Contaminants
The xylene PEL is listed in OSHA's air contaminants standard, 29 CFR 1910.1000, Table Z-1. Employers must keep exposures at or below the PEL and use feasible engineering and administrative controls first, with respirators when those controls are not enough.
Respiratory Protection
When respirators are used, OSHA's respiratory protection standard, 29 CFR 1910.134, requires a written program, medical evaluation, fit testing and training.
Medical and Biological Monitoring for Xylene
According to ATSDR, xylene and its breakdown products can be detected in urine, and xylene itself can be detected in blood. Because the body breaks down and eliminates xylene fairly quickly, timing matters: samples reflect recent exposure and must be collected at the right point relative to the work shift to be meaningful. ATSDR also notes that these tests cannot tell whether a person will develop health effects, and they are not routinely available in doctors' offices.
For most employers, air monitoring is the primary tool for assessing xylene exposure. Biological monitoring can add value where skin contact is significant, where respirators are relied on, or when investigating symptoms, and it should be designed and interpreted by an occupational health professional. For more on how the body handles foreign chemicals, see xenobiotic.
Controlling Xylene Exposure: Step by Step
- Identify uses. Check SDSs for xylene in paints, thinners, coatings, adhesives and cleaners. Products may list it as xylene, mixed xylenes, dimethylbenzene or one of the isomers.
- Consider substitution. Ask whether a lower-hazard product can do the job.
- Ventilate. Use local exhaust ventilation at the source, such as spray booths and fume hoods, and general ventilation in work areas.
- Monitor exposure. Conduct air sampling for full-shift and short-term exposures and compare results to the PEL, REL and STEL.
- Protect the skin. Select gloves rated for xylene based on manufacturer breakthrough data. Many common glove materials degrade quickly in aromatic solvents.
- Protect the eyes. Use chemical splash goggles and provide eyewash where splashes can occur.
- Use respirators when needed. Select respirators based on measured concentrations under a written program.
- Plan for spills and confined spaces. Xylene vapor can quickly reach hazardous levels in tanks and pits, so treat these as confined spaces and test the atmosphere before entry.
Examples of Xylene Exposure
- A painter spraying a xylene-based coating in a small room without exhaust ventilation develops dizziness and headache.
- A laboratory technician uses xylene in an open tray outside a fume hood and reports eye and throat irritation.
- A maintenance worker cleans parts with xylene using bare hands and develops dermatitis.
- A worker enters a tank to clean residue without atmospheric testing and becomes disoriented.
Best Practices
- Keep containers closed when not in use to reduce vapor release.
- Use the smallest quantity needed for the task.
- Prohibit eating, drinking and smoking where xylene is used.
- Change out of solvent-soaked clothing immediately and wash affected skin with soap and water.
- Include xylene tasks in your job hazard analysis and exposure monitoring plan.
How SMS360 Helps
The SMS360 Safety Data Sheets module helps employers keep current SDSs for xylene and xylene-containing products available to workers on any device. Safety teams can see where these products are used across sites, support labeling and hazard communication training, and quickly find first aid and spill information when it is needed.
Frequently Asked Questions
What is the OSHA exposure limit for xylene?
OSHA's permissible exposure limit for xylene is 100 ppm (435 mg/m³) as an 8-hour time-weighted average. NIOSH recommends the same 100 ppm TWA plus a 150 ppm short-term exposure limit.
Can xylene be absorbed through the skin?
Yes. NIOSH lists skin absorption as a route of exposure for xylene. Liquid contact can also irritate the skin and cause dermatitis. Use gloves made of a material rated for xylene and replace them according to breakthrough data.
Is xylene a carcinogen?
According to ATSDR, EPA found the available data inadequate to assess whether xylene causes cancer, and IARC considers it not classifiable as to its carcinogenicity to humans. Its main recognized hazards are central nervous system effects, irritation and flammability.
What should a worker do after overexposure to xylene?
Move the worker to fresh air, remove contaminated clothing and wash skin with soap and water. NIOSH first aid guidance calls for irrigating eyes immediately, providing respiratory support if needed and getting medical attention immediately if xylene is swallowed. Follow the first aid section of the product's SDS.
