P-Xylene

H226: Flammable liquid and vapor [Warning Flammable liquids]

H312: Harmful in contact with skin [Warning Acute toxicity, dermal]

H315: Causes skin irritation [Warning Skin corrosion/irritation]

H332: Harmful if inhaled [Warning Acute toxicity, inhalation]

P210, P233, P240, P241, P242, P243, P261, P264, P271, P280, P302+P352, P303+P361+P353, P304+P340, P317, P321, P332+P317, P362+P364, P370+P378, P403+P235, and P501 (click each P-code to see the statement)

This chemical does not meet GHS hazard criteria for 0.8% (11 of 1380) of reports.

H226 (99.2%): Flammable liquid and vapor [Warning Flammable liquids]

H304 (20.8%): May be fatal if swallowed and enters airways [Danger Aspiration hazard]

H312+H332 (10.2%): Harmful in contact with skin or if inhaled [Warning Acute toxicity, dermal; acute toxicity, inhalation]

H312 (99.1%): Harmful in contact with skin [Warning Acute toxicity, dermal]

H315 (99.2%): Causes skin irritation [Warning Skin corrosion/irritation]

H319 (53.1%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]

H332 (99.2%): Harmful if inhaled [Warning Acute toxicity, inhalation]

H335 (21.1%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

H412 (19.7%): Harmful to aquatic life with long lasting effects [Hazardous to the aquatic environment, long-term hazard]

P210, P233, P240, P241, P242, P243, P261, P264, P264+P265, P271, P273, P280, P301+P316, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P317, P319, P321, P331, P332+P317, P337+P317, P362+P364, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 1380 reports by companies from 28 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Reported as not meeting GHS hazard criteria per 11 of 1380 reports by companies.

There are 27 notifications provided by 1369 of 1380 reports by companies with hazard statement code(s).

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

H304: May be fatal if swallowed and enters airways [Danger Aspiration hazard]

H335: May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

H336: May cause drowsiness or dizziness [Warning Specific target organ toxicity, single exposure; Narcotic effects]

H361: Suspected of damaging fertility or the unborn child [Warning Reproductive toxicity]

H370: Causes damage to organs [Danger Specific target organ toxicity, single exposure]

H401: Toxic to aquatic life [Hazardous to the aquatic environment, acute hazard]

H411: Toxic to aquatic life with long lasting effects [Hazardous to the aquatic environment, long-term hazard]

P203, P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P273, P280, P301+P316, P302+P352, P303+P361+P353, P304+P340, P308+P316, P317, P318, P319, P321, P331, P332+P317, P362+P364, P370+P378, P391, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

H303: May be harmful if swallowed [Warning Acute toxicity, oral]

H319: Causes serious eye irritation [Warning Serious eye damage/eye irritation]

H360: May damage fertility or the unborn child [Danger Reproductive toxicity]

H371: May cause damage to organs [Warning Specific target organ toxicity, single exposure]

P203, P210, P233, P240, P241, P242, P243, P260, P261, P264, P264+P265, P270, P271, P280, P301+P316, P301+P317, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P308+P316, P317, P318, P319, P321, P331, P332+P317, P337+P317, P362+P364, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

P210, P233, P240, P241, P242, P243, P261, P264, P271, P280, P301+P316, P302+P352, P303+P361+P353, P304+P340, P317, P319, P321, P331, P332+P317, P362+P364, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

P210, P233, P240, P241, P242, P243, P261, P264, P271, P273, P280, P302+P352, P303+P361+P353, P304+P340, P317, P321, P332+P317, P362+P364, P370+P378, P403+P235, and P501 (click each P-code to see the statement)

Fresh air, rest. Refer for medical attention.

First rinse with plenty of water for at least 15 minutes, then remove contaminated clothes and rinse again. Rinse and then wash skin with water and soap.

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Rinse mouth. Do NOT induce vomiting. Refer for medical attention .

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. If symptoms such as redness or irritation develop, IMMEDIATELY call a physician and be prepared to transport the victim to a hospital for treatment.

INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. If symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop, call a physician and be prepared to transport the victim to a hospital. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to that advised under Protective Clothing.

INGESTION: DO NOT INDUCE VOMITING. If the victim is conscious and not convulsing, give 1 or 2 glasses of water to dilute the chemical and IMMEDIATELY call a hospital or poison control center. Be prepared to transport the victim to a hospital if advised by a physician. If the victim is convulsing or unconscious, do not give anything by mouth, ensure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. DO NOT INDUCE VOMITING. IMMEDIATELY transport the victim to a hospital. (NTP, 1992)

(General first aid procedures)

Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.

Skin: Soap wash promptly - If this chemical contacts the skin, promptly wash the contaminated skin with soap and water. If this chemical penetrates the clothing, promptly remove the clothing and wash the skin with soap and water. Get medical attention promptly.

Breathing: Respiratory support

Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately.

Fire Extinguishing Agents Not to Be Used: Water may be ineffective.

Fire Extinguishing Agents: Foam, dry chemical, or carbon dioxide (USCG, 1999)

Use water spray, powder, foam, carbon dioxide. In case of fire: keep drums, etc., cool by spraying with water.

Suitable extinguishing media: Use water spray, alcohol-resistant foam, dry chemical, or carbon dioxide.

Advice for firefighters: Wear self-contained breathing apparatus for firefighting if necessary.

Use water spray to cool unopened containers.

Foam, dry chemical or carbon dioxide. Water may be ineffective. Cool exposed containers with water.

Excerpt from ERG Guide 130 [Flammable Liquids (Water-Immiscible / Noxious)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 50 meters (150 feet) in all directions.

LARGE SPILL: Consider initial downwind evacuation for at least 300 meters (1000 feet).

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)

Personal protection: filter respirator for organic gases and vapours adapted to the airborne concentration of the substance. Ventilation. Remove all ignition sources. Do NOT let this chemical enter the environment. Collect leaking and spilled liquid in sealable containers as far as possible. Absorb remaining liquid in sand or inert absorbent. Then store and dispose of according to local regulations.

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Use personal protective equipment. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Remove all sources of ignition. Beware of vapors accumulating to form explosive concentrations. Vapors can accumulate in low areas. Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided. Methods and materials for containment and cleaning up: Contain spillage, and then collect with an electrically protected vacuum cleaner or by wet-brushing and place in container for disposal according to local regulations.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

Generators of waste (equal to or greater than 100 kg/mo) containing this contaminant, EPA hazardous waste number U239 and F003, must conform with USEPA regulations in storage, transportation, treatment and disposal of waste.

Product: Burn in a chemical incinerator equipped with an afterburner and scrubber but exert extra care in igniting as this material is highly flammable. Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material; Contaminated packaging: Dispose of as unused product.

p-Xylene is a waste chemical stream constituent which may be subjected to ultimate disposal by controlled incineration.

Xylene is a waste chemical stream constituent which may be subjected to ultimate disposal by controlled incineration.

SRP: The scientific literature for the use of contact lenses by industrial workers is inconsistent. The benefits or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.

SRP: Contaminated protective clothing should be segregated in a manner such that there is no direct personal contact by personnel who handle, dispose, or clean the clothing. The completeness of the cleaning procedures should be considered before the decontaminated protective clothing is returned for reuse by the workers. Contaminated clothing should not be taken home at the end of shift, but should remain at employee's place of work for cleaning.

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Use personal protective equipment. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Remove all sources of ignition. Beware of vapors accumulating to form explosive concentrations. Vapors can accumulate in low areas. Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided.

Precautions for safe handling: Avoid contact with skin and eyes. Avoid inhalation of vapor or mist. Keep away from sources of ignition - No smoking. Take measures to prevent the build up of electrostatic charge.

For more Preventive Measures (Complete) data for 4-XYLENE (8 total), please visit the HSDB record page.

SMALL SPILLS AND LEAKAGE: If you should spill this chemical, use absorbent paper to pick up all liquid spill material. Your contaminated clothing and absorbent paper should be sealed in a vapor-tight plastic bag for eventual disposal. Solvent wash all contaminated surfaces with acetone followed by washing with a strong soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.

STORAGE PRECAUTIONS: You should store this material in a refrigerator. (NTP, 1992)

Fireproof. Store only in original container. Separated from strong oxidants and strong acids. Store in an area without drain or sewer access.

Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage.

Ambient storage temp and open (flame arrester), or pressure-vacuum.

Biological Exposure Indices (BEI) [ACGIH] - Xylenes (technical or commercial grades): 0.3 g/g creatine methylhippuric acids in urine at end of shift; [ACGIH TLVs and BEIs]

100.0 [ppm]

TWA 100 ppm (435 mg/m3) ST 150 ppm (655 mg/m3)

TWA 100 ppm (435 mg/m3) See Appendix G

900 ppm (NIOSH, 2024)

900.0 [ppm]

See: 95476

150.0 [ppm]

8 hr Time Weighted Avg (TWA): 100 ppm; 15 min Short Term Exposure Limit (STEL): 150 ppm. /Xylene (o-, m-, & p- isomers)/

A4; Not classifiable as a human carcinogen. /Xylene (o-,m-, & p- isomers)/

Biological Exposure Index (BEI): Determinant: methylhippuric acids in urine; Sampling Time: end of shift; BEI: 1.5 g/g creatinine. /Xylenes, technical or commercial grade/

100 ppm as TWA; 150 ppm as STEL; A4 (not classifiable as a human carcinogen); BEI issued.

221 mg/m

Acute Inhalation: 2 ppm (L165)

Intermediate Inhalation: 0.6 ppm (L165)

Chronic Inhalation: 0.05 ppm (L165)

Acute Oral: 1 mg/kg/day (L165)

Intermediate Oral: 0.4 mg/kg/day (L165)

Chronic Oral: 0.2 mg/kg/day (L165)

DOE Protective Action Criteria (PAC): Temporary Emergency Exposure Limits (TEELs) for 4-Xylene: TEEL-0: 100 ppm; PAC-1: 150 ppm; PAC-2: 200 ppm; PAC-3: 900 ppm (TEEL-0: The threshold concentration below which most people will experience no adverse health effects; PAC-1: The maximum concentration in air below which it is believed nearly all individuals could be exposed for up to one hour without experiencing other than mild transient adverse health effects or perceiving a clearly defined objectionable odor; PAC-2: The maximum concentration in air below which it is believed nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms that could impair their abilities to take protective action; PAC-3: The maximum concentration in air below which it is believed nearly all individuals could be exposed for up to one hour without experiencing or developing life-threatening health effects).

A harmful contamination of the air will be reached rather slowly on evaporation of this substance at 20 °C.

The substance is irritating to the eyes, skin and respiratory tract. If this liquid is swallowed, aspiration into the lungs may result in chemical pneumonitis. The substance may cause effects on the central nervous system. This may result in impaired functions.

The substance defats the skin, which may cause dryness or cracking. The substance may have effects on the central nervous system. Exposure to the substance may increase noise-induced hearing loss. Animal tests show that this substance possibly causes toxicity to human reproduction or development.

Excerpt from NIOSH Pocket Guide for p-Xylene:

Skin: PREVENT SKIN CONTACT - Wear appropriate personal protective clothing to prevent skin contact.

Eyes: PREVENT EYE CONTACT - Wear appropriate eye protection to prevent eye contact.

Wash skin: WHEN CONTAMINATED - The worker should immediately wash the skin when it becomes contaminated.

Remove: WHEN WET (FLAMMABLE) - Work clothing that becomes wet should be immediately removed due to its flammability hazard (i.e., for liquids with a flash point <100 °F).

Change: No recommendation is made specifying the need for the worker to change clothing after the workshift. (NIOSH, 2024)

Eye/face protection: Face shield and safety glasses. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).

Skin protection: Handle with gloves.

Body Protection: Complete suit protecting against chemicals. Flame retardant antistatic protective clothing. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.

Respiratory protection: Where risk assessment shows air-purifying respirators are appropriate use a full-face respirator with multipurpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls. If the respirator is the sole means of protection, use a full-face supplied air respirator. Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).

For more Personal Protective Equipment (PPE) (Complete) data for 4-XYLENE (9 total), please visit the HSDB record page.

NIOSH/OSHA

Up to 900 ppm:

(APF = 10) Any chemical cartridge respirator with organic vapor cartridge(s)*

(APF = 25) Any powered, air-purifying respirator with organic vapor cartridge(s)*

(APF = 10) Any supplied-air respirator*

(APF = 50) Any self-contained breathing apparatus with a full facepiece

Emergency or planned entry into unknown concentrations or IDLH conditions:

(APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode

(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus

(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister

Any appropriate escape-type, self-contained breathing apparatus

P-xylene appears as a colorless watery liquid with a sweet odor. Less dense than water. Insoluble in water. Irritating vapor. Freezing point is 56 °F. (USCG, 1999)

Colorless solid at low temperature; mp = 13-14 deg C; [Merck Index] Colorless liquid with a sweet odor; [CHRIS]

COLOURLESS LIQUID WITH CHARACTERISTIC ODOUR.

Colorless liquid with an aromatic odor. [Note: A solid below 56 °F.]

Colorless plates or prisms at low temp

Colorless liquid [Note: A solid below 56 degrees F]

Color: Saybolt units +30 (research, pure & technical grades)

Aromatic odor

Characteristic odor

280.9 °F at 760 mmHg (NTP, 1992)

138.3 °C

p-Xylene and m-xylene cannot be separated by distillation because their boiling points are too close.

55.9 °F (NTP, 1992)

81 °F (NTP, 1992)

25.0 °C (77.0 °F) - closed cup

77 °F (25 °C) (Closed cup)

25 °C c.c.

Insoluble. (NTP, 1992)

In water, 1.62X10+2 mg/L at 25 °C

In water, 165 mg/L at 25 °C (average of 15 literature values ranging from 130-215 mg/L at 25 °C)

Miscible in alcohol, ether, acetone, benzene; soluble in chloroform

Solubility in water, g/l at 25 °C: 0.2 (very slightly soluble)

0.861 at 68 °F (USCG, 1999) - Less dense than water; will float

0.86104 at 20 °C/4 °C

Critical density: 2.64 mmol/cu cm; Critical volume: 379.0 cu cm/mol

Relative density (water = 1): 0.86 (20 °C)

3.66 (NTP, 1992) - Heavier than air; will sink (Relative to Air)

3.66 (Air = 1)

Relative vapor density (air = 1): 3.7

10 mmHg at 81.1 °F (NTP, 1992)

8.84 [mmHg]

8.84 mm Hg at 25 °C

Vapor pressure, kPa at 20 °C: 0.9

log Kow = 3.15

Henry's Law constant = 6.90X10-3 atm-cu m/mol at 25 °C

Stable under recommended storage conditions.

984 °F (USCG, 1999)

984 °F (528 °C)

When heated to decomposition it emits acrid smoke and irritating fumes.

Hazardous decomposition products formed under fire conditions - Carbon oxides.

Highly flammable. Insoluble in water.

Hydrocarbons, Aromatic

Highly Flammable

P-XYLENE may react with oxidizing materials. (NTP, 1992). Acetic acid forms explosive mixtures with p-xylene and air (Shraer, B.I. 1970. Khim. Prom. 46(10):747-750.).

Incompatible materials: Strong oxidizing agents.

In liquid phase aerobic oxidation of p-xylene in acetic acid to terephthalic acid, it is important to eliminate the inherent hazards of this fuel-air mixture. Effects of temp, pressure and presence of steam on explosive limits of the mixture have been investigated.

Oxidation of p-xylene with nitric acid under pressure in manufacture of terephthalic acid is an explosion hazard in autoclaves and condensing systems.

Can react with oxidizing materials.

For more Hazardous Reactivities and Incompatibilities (Complete) data for 4-XYLENE (6 total), please visit the HSDB record page.

Strong oxidizers, strong acids

IDENTIFICATION AND USE: 4-Xylene (p-xylene) is a colorless liquid (Note: A solid below 56 degrees F). It is used for synthesis of terephthalic acid for polyester resins and fibers; pharmaceutical synthesis; insecticides. p-Xylene is also frequently used for paints or in the printing trade. HUMAN EXPOSURE AND TOXICITY: Three women exposed to p-xylene at 100 ppm for 1 to 7.5 hours/day, for 5 days, showed no effects on electroencephalograms, evoked potentials, or cognitive performance, but frequently reported headache and dizziness as a result of exposure. In contrast, four men exposed at concentrations of up to 150 ppm p-xylene under the same exposure conditions reported no increase in headaches or dizziness. Slight impairment of vestibular and visual function and reaction time was noted at exposure levels from 200 to 300 ppm. There was adaption to the impairment over five successive daily exposures. Human data indicate that acute inhalation exposures to 460 ppm mixed xylene and 100 ppm p-xylene vapors produce mild and transient eye irritation. p-Xylene is possibly ototoxic at concentrations that are relevant to the occupational setting. Levels of blood xylenes reflect recent exposure. The m-and p-xylene isomers usually are measured together and reported as m/p-xylene. ANIMAL STUDIES: Increased hepatic cytochrome p450 concentrations and reduced nicotinamide adenine dinucleotide cytochrome C reductase activity occurred in rats exposed 3 days to 2000 ppm of p-xylene. In lung microsomes, cytochrome p450 content was decreased. Marked activation and tremor were observed at concentrations between 400 and 1500 ppm p-xylene in rats. The CNS depressant threshold was 1940 ppm. In a study of levels of noradrenaline and dopamine in the forebrain and hypothalamus, rats (six males/group) were exposed to 0 or 2000 ppm p-xylene 6 hr/day for 3 days. The animals were killed 16-18 hr after the last exposure. In exposed animals there was a significant increase in catecholamine levels and turnover in various parts of the hypothalamus. There was no effect on dopamine levels or turnover in the forebrain. Histological damage to the outer hair cells of the organ of Corti provided evidence of ototoxicity in rats exposed by oral gavage to p-xylene, but not m- or o-xylene, at a dose of 900 mg/kg/day, 5 days/week for 2 weeks. The losses of hair cells occurred in the area of the cochlea responsive to medium frequencies (10-25 kHz). Mice were exposed to p-xylene at 150, 1500, or 3000 mg/cu m, 24 hr/day from days 7-14 of gestation. Toxic effects were decr weight of fetuses, increased incidence of skeletal retardation, and decrease in activity of enzymes, succinic dehydrogenase, alkaline, acid phosphatase, glucose 6-phosphatase and changed characteristic features of functional maturity of the nephron, retardation of fetus was dose related. In other experiment, increased incidence of malformations mostly cleft palates, were observed only with m- or p-xylene. Malformations (ie cleft palate) associated with mixed or individual isomers were primarily reported at maternally toxic doses. Each xylene isomer was administered to male rats intraperitoneally in 2 similar doses, 24 hours apart over a range of concentrations from 0, 0.12-0.75 mL/kg (105-650 mg/kg) and evaluated femoral bone marrow 30 hours after the first injection. No increase in micronucleated polychromatic erythrocytes was observed for any xylene isomer. p-Xylene was nonmutagenic using the Ames assay. It did not revert Salmonella typhimurium strains TA1535, TA1537, TA1538, TA98, & TA100 either with or without metabolic activation. ECOTOXICITY STUDIES: The xylene isomers have a similar degree of toxicity as mixed xylenes to estuarine/marine invertebrates. For m-xylene and p-xylene, the respective 48-hour LC50 values are 19.3 and 24.5 mg/L in brine shrimp, suggesting that the m-xylene and p-xylene isomers are slightly toxic to estuarine/marine invertebrates on an acute basis.

p-Xylene is a cholinesterase or acetylcholinesterase (AChE) inhibitor. A cholinesterase inhibitor (or 'anticholinesterase') suppresses the action of acetylcholinesterase. Because of its essential function, chemicals that interfere with the action of acetylcholinesterase are potent neurotoxins, causing excessive salivation and eye-watering in low doses, followed by muscle spasms and ultimately death. Nerve gases and many substances used in insecticides have been shown to act by binding a serine in the active site of acetylcholine esterase, inhibiting the enzyme completely. Acetylcholine esterase breaks down the neurotransmitter acetylcholine, which is released at nerve and muscle junctions, in order to allow the muscle or organ to relax. The result of acetylcholine esterase inhibition is that acetylcholine builds up and continues to act so that any nerve impulses are continually transmitted and muscle contractions do not stop. Among the most common acetylcholinesterase inhibitors are phosphorus-based compounds, which are designed to bind to the active site of the enzyme. The structural requirements are a phosphorus atom bearing two lipophilic groups, a leaving group (such as a halide or thiocyanate), and a terminal oxygen.

Evaluation: There is inadequate evidence in humans for the carcinogenicity of xylenes. There is inadequate evidence in experimental animals for the carcinogenicity of xylenes. Overall classification: Xylenes are not classifiable as to their carcinogenicity to humans (Group 3)./Xylenes, o,m,p isomers/

CLASSIFICATION: D; not classifiable as to human carcinogenicity. BASIS FOR CLASSIFICATION: Orally administered technical xylene mixtures did not result in significant increases in incidences in tumor responses in rats or mice of both sexes. HUMAN CARCINOGENICITY DATA: None. ANIMAL CARCINOGENICITY DATA: Inadequate. /based on former classification system/

Under the Draft Revised Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1999), data are inadequate for an assessment of the carcinogenic potential of xylenes. Adequate human data on the carcinogenicity of xylenes are not available, and the available animal data are inconclusive as to the ability of xylenes to cause a carcinogenic response. Evaluations of the genotoxic effects of xylenes have consistently given negative results. /Xylenes/

A4; Not classifiable as a human carcinogen. /Xylene (o-, m-, & p- isomers)/

3, not classifiable as to its carcinogenicity to humans. (L135)

Acute exposure to cholinesterase inhibitors can cause a cholinergic crisis characterized by severe nausea/vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved. Accumulation of ACh at motor nerves causes overstimulation of nicotinic expression at the neuromuscular junction. When this occurs symptoms such as muscle weakness, fatigue, muscle cramps, fasciculation, and paralysis can be seen. When there is an accumulation of ACh at autonomic ganglia this causes overstimulation of nicotinic expression in the sympathetic system. Symptoms associated with this are hypertension, and hypoglycemia. Overstimulation of nicotinic acetylcholine receptors in the central nervous system, due to accumulation of ACh, results in anxiety, headache, convulsions, ataxia, depression of respiration and circulation, tremor, general weakness, and potentially coma. When there is expression of muscarinic overstimulation due to excess acetylcholine at muscarinic acetylcholine receptors symptoms of visual disturbances, tightness in chest, wheezing due to bronchoconstriction, increased bronchial secretions, increased salivation, lacrimation, sweating, peristalsis, and urination can occur. Certain reproductive effects in fertility, growth, and development for males and females have been linked specifically to organophosphate pesticide exposure. Most of the research on reproductive effects has been conducted on farmers working with pesticides and insecticdes in rural areas. In females menstrual cycle disturbances, longer pregnancies, spontaneous abortions, stillbirths, and some developmental effects in offspring have been linked to organophosphate pesticide exposure. Prenatal exposure has been linked to impaired fetal growth and development. Neurotoxic effects have also been linked to poisoning with OP pesticides causing four neurotoxic effects in humans: cholinergic syndrome, intermediate syndrome, organophosphate-induced delayed polyneuropathy (OPIDP), and chronic organophosphate-induced neuropsychiatric disorder (COPIND). These syndromes result after acute and chronic exposure to OP pesticides.

The substance can be absorbed into the body by inhalation, through the skin and by ingestion.

inhalation, skin absorption, ingestion, skin and/or eye contact

Oral (L165) ; inhalation (L165) ; dermal (L165)

Dizziness. Drowsiness. Headache. Nausea.

Dry skin. Redness.

Redness. Pain.

Burning sensation. Abdominal pain. Further see Inhalation.

irritation eyes, skin, nose, throat; dizziness, excitement, drowsiness, incoordination, staggering gait; corneal vacuolization; anorexia, nausea, vomiting, abdominal pain; dermatitis

Inhalation and ingestion can lead to dizziness, drowsiness, headache, and nausea. Burning sensations and abdominal pain can also result from ingestion. Dermal and eye exposure can cause skin dryness, redness, and pain. Conjunctivitis, dermatitis, respiratory tract irritation, dyspnea, anorexia, vomiting, fatigue, vertigo, incoordination, irritation, gangrene and anemia are other symptoms following xylene poisoning. (A579)

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

Neurotoxin - Acute solvent syndrome

Occupational hepatotoxin - Secondary hepatotoxins: the potential for toxic effect in the occupational setting is based on cases of poisoning by human ingestion or animal experimentation.

ACGIH Carcinogen - Not Classifiable.

SURROGATE. See Xylenes

LC50 (rat) = 4,550 ppm4hr

LC50: 4740 ppm (Inhalation, Rat) (L165)

LC50: 3907 ppm (Inhalation, Mouse) (L165)

LD50 Rat oral 4029 mg/kg bw

LD50 Mice ip 2110 mg/kg

LD50 Rat ip 3810 mg/kg

LC50 Rat inhal 4550 ppm/4 hr

For more Non-Human Toxicity Values (Complete) data for 4-XYLENE (6 total), please visit the HSDB record page.

If the compound has been ingested, rapid gastric lavage should be performed using 5% sodium bicarbonate. For skin contact, the skin should be washed with soap and water. If the compound has entered the eyes, they should be washed with large quantities of isotonic saline or water. In serious cases, atropine and/or pralidoxime should be administered. Anti-cholinergic drugs work to counteract the effects of excess acetylcholine and reactivate AChE. Atropine can be used as an antidote in conjunction with pralidoxime or other pyridinium oximes (such as trimedoxime or obidoxime), though the use of '-oximes' has been found to be of no benefit, or possibly harmful, in at least two meta-analyses. Atropine is a muscarinic antagonist, and thus blocks the action of acetylcholine peripherally.

Sixteen men were studied in an exposure chamber to assess the effect of four hr exposure to toluene (3.25 mmol/cu m), p-xylene (2.84 mmol/cu m) a mixture of toluene and p-xylene (2.20 + 0.94 mmol/cu m) and a control condition. With the aid of microcomputers subjects performed tests of simple reaction time, short term memory, and choice reaction time immediately after entering the chamber, after two, and after four hours of exposure. The results indicate that the performance on the tests was unaffected by exposure. In the light of this result, the risk of an acute effect on central nervous functions after exposure for four hours at these concn was considered to be minimal.

Eight male subjects were experimentally exposed to toluene, p-xylene, and a combination of toluene and p-xylene to study the influence of coexposure and exposure to different levels of each solvent on their uptake and elimination. The exposures were performed for 4 hr at exposure levels equivalent to or lower than the Swedish threshold limit value for toluene, 300 mg/cu m (3.2 mmol/cu m). During and after the exposure, solvent concentrations were measured in blood and in expired air. In addition, the pulmonary ventilation rate was measured during the exposure. Decreases in the blood/end exhaled air concentration ratio were found for both toluene and p-xylene when given in combination compared with separate exposure. The total solvent uptake relative to the exposure level was decreased after exposure to the higher solvent concentration, and the apparent clearance was also decreased after exposure to the higher concentration of solvent. Finally, the blood solvent concentration were lower at the end of the exposure compared with the maximal concentration during each exposure condition. In the kinetics of toluene and p-xylene, the total amount of toluene or p-xylene, or both, seems to be of major importance. The change in blood/end exhaled air concentration ratio may indicate an effect of coexposure.

It is unclear whether the pneumotoxicity observed with bromobenzene in phenobarbital-induced rats is related to bromobenzene bioactivation in lung, liver or both. To help differentiate pulmonary from hepatic bioactivation, bromobenzene was admin alone and in combination with p-xylene, which inhibits pulmonary but induces hepatic cytochrome P450. Exposure to p-xylene alone (3400 ppm for 4 hr) produced no changes in bronchoalveolar lavage fluid measurements ... or serum sorbitol dehydrogenase. p-Xylene incr hepatic microsomal benzyloxy-, pentoxy-, and ethoxy-resorufin O-dealkylase activities but decr pulmonary microsomal benzyloxy- and pentoxy-resorufin O-dealkylase activities. Immunoblot analysis revealed an induction of hepatic but not pulmonary microsomal P450IIB apoprotein. When rats were exposed to p-xylene (2800 ppm) or room air for 4 hr, treated 12 hr later with bromobenzene (0.5 mL/kg, ip) or corn oil, and killed after 12 hr, p-xylene incr hepatic P450IIB (27-fold) concomitant with a similar incr in benzyloxy-resorufin O-dealkylase activity. p-Xylene also incr hepatic P450IA apoprotein (3 to 4-fold) with a complimentary incr in ethoxy-resorufin O-dealkylase activity. p-Xylene potentiated bromobenzene-induced hepatotoxicity. In pulmonary microsomes p-xylene and bromobenzene each produced similar decr in both ethoxy- and benzyloxy-resorufin O-dealkylase activities. The combination of p-xylene and bromobenzene had an additive effect on pulmonary P450IA1 reduction. Bronchoalveolar lavage fluid analysis and histopathology revealed no pneumotoxicity with any treatment. p-Xylene potentiation of bromobenzene-induced hepatotoxicity without pneumotoxicity suggests that the liver does not produced metabolites of bromobenzene which are directly involved in pulmonary damage.

The effects of p-xylene and ethanol on the lung metabolism of benzo(a)pyrene were studied. p-Xylene was admin by ip injection at doses ranging from 0.1 to 1.0 g/kg (1:1 in soybean oil). Ethanol was admin po at 5 g/kg (40% w/v). Rats given p-xylene, ethanol, or p-xylene and ethanol were sacrificed 1 hr after treatment. Additional time points of 15 min, 30 min, 4 hr, and 24 hr after p-xylene (1 g/kg) were examined. 3-Hydroxy-benzo(a)pyrene (3-OH) formation was measured fluorometrically as aryl hydrocarbon hydroxylase activity in lung microsomes. p-Xylene (1 g/kg) inhibited the formation of 3-OH benzo(a)pyrene 40% at 15 min, 27% at 30 min, 43% at 1 hr, and 39% at 4 hr after treatment. Inhibition of aryl hydrocarbon hydroxylase activity was still present 24 hr after dosing (41%). Aryl hydrocarbon hydroxylase activity was inhibited 27% and 46% at 0.5 mg/kg and 1.0 mg/kg p-xylene (1 hr), respectively, while the lowest dose (0.1 mg/kg) did not change activity. Analysis of the major metabolites of benzo(a)pyrene by HPLC demonstrated that the formation of 3-OH and 4,5-diol benzo(a)pyrene were inhibited 32% and 50%, respectively, in lung microsomes prepared 24 hr after a single injection of p-xylene (1 g/kg). None of the other metabolites analyzed were changed by p-xylene. Ethanol had no effect on 3-OH benzo(a)pyrene formation during a 1-hr treatment. A combined dose of ethanol and p-xylene moderately inhibited 3-OH benzo(a)pyrene formation. These findings indicate that benzo(a)pyrene detoxication (i.e., 3-OH formation) in rat lung is selectively inhibited by p-xylene but not ethanol. Ethanol appears to modify the inhibitory effect of p-xylene.

For more Interactions (Complete) data for 4-XYLENE (6 total), please visit the HSDB record page.

Immediate First Aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Aromatic hydrocarbons and related compounds/

Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary. ... For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 mL/kg up to 200 L of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool. Administer activated charcoal ... . /Aromatic hydrocarbons and related compounds/

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag-valve-mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start IV administration of D5W TKO /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam (Valium) or lorazepam (Ativan) ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Aromatics hydrocarbons and related compounds/

Emergency and supportive measures: Inhalation exposure. Maintain an open airway and assist ventilation if necessary. Administer supplemental oxygen and monitor oxygenation. If the patient is coughing or dyspneic, consider aspiration pneumonia. Treat for hydrocarbon pneumonia. If the patient remains asymptomatic after a 6-hour observation, chemical pneumonia is unlikely, and further observation or chest radiography is not needed. Treat coma, arrhythmias and bronchospasm if they occur. Caution: Epinephrine and other sympathomimetic amines may provoke or aggravate cardiac arrhythmias. Tachyarrhythmias may be treated with propranolol ... or esmolol. /Toluene and xylene/

Decontamination: Patients exposed only to solvent vapor who have no skin or eye irritation do not need decontamination. However, victims whose clothing or skin is contaminated with liquid can secondarily contaminate response personnel by direct contact or through off-gassing vapor. Inhalation. Remove the victim from exposure and give supplemental oxygen if available. Skin and eyes. Remove contaminated clothing and wash exposed skin with soap and water. Flush exposed or irritated eyes with plain water or saline. Ingestion. Administer activated charcoal orally if conditions are appropriate. Consider gastric lavage for large ingestions (>1-2 oz) if it can be performed within 30 minutes of ingestion. /Toluene and xylene/

LC100; Species: Tetrahymena pyriformis (Ciliate); Concentration: 3.77 mmole/L for 24 hr /Conditions of bioassay not specified/

LC50; Species: Crangon franciscorum (Shrimp); Concentration: 2.0 ppm for 96 hr /Conditions of bioassay not specified/

EC50; Species: Chlamydomonas angulosa (Green algae) age 72-96 hr exponential growth phase, 5X10+4 cells/mL; Conditions: static, 19 °C, pH 6.5; Concentration: 430 mmol/cu m for 3 hr; Effect: physiology, photosynthesis /formulated product/

EC50; Species: Chlorella vulgaris (Green algae) age 3-4 days exponential growth phase, 20X10+4 cells/mL; Conditions: static, 19 °C, pH 6.5; Concentration: 990 mmol/cu m for 3 hr; Effect: physiology, photosynthesis /formulated product/

For more Ecotoxicity Values (Complete) data for 4-XYLENE (16 total), please visit the HSDB record page.

/AQUATIC SPECIES/ ... Cod eggs (Gadus morhus L.)/were exposed/ to xylene isomers in covered glass dishes and monitored the effects both during fertilization and during early cleavage of fertilized eggs. Both m-xylene and p-xylene induced significant decreases in the fertilization rate at concentrations above 10 mg/L. o-Xylene had no significant effect on the fertilization rate at concentrations of 16-35 mg/L. Fertilized eggs were exposed to xylene for 3 or 6 hr before first cleavage. No significant difference was observed between the individual xylene isomers or between the two exposure periods. Effects on the early cleavage pattern were significant for xylene concentrations between 2 and 7 mg/L. The effects seen included inhibition of formation of the cleavage furrow. Small cells or a total absence of cleavage occurred on exposure to all isomers at concentrations of 16-35 mg/L, while incomplete or uneven cleavage was found at exposures of 8-15 mg/L.

/AQUATIC SPECIES/ In rainbow trout exposed to 0.001, 0.01, and 0.1 mg/L p-xylene for 1 hour, fish exhibited attractant behavior at a concentration of 0.01 mg/L, but avoidance behavior at a concentration of 0.1 mg/L...[U.S. EPA Office of Prevention, Pesticides and Toxic Substances; Environmental Fate and Ecological Risk Assessment for the Reregistration of Xylene Range Aromatic Solvents p.40 (October 4, 2005) EPA Docket No. EPA HQ-OPP-2006-0145-0002

/AQUATIC SPECIES/ No studies on the acute effects of mixed xylenes in algae were identified from the available literature. The acute toxicity of xylene isomers was evaluated in two studies using Selenastrum capricornutum, a green algae .... 72-hour EC50 values for growth inhibition ranging from 3.2 mg a.i./L for p-xylene to 4.9 mg a.i/L for m-xylene /were reported/. ... 8-day EC50 values for growth inhibition ranging from 3.9 mg/L for m-xylene to 4.4 mg/L for p-xylene /were reported/.[U.S. EPA Office of Prevention, Pesticides and Toxic Substances; Environmental Fate and Ecological Risk Assessment for the Reregistration of Xylene Range Aromatic Solvents 133 pp. (October 4, 2005) EPA Docket No. EPA HQ-OPP-2006-0145-0002

/AQUATIC SPECIES/ ... The xylene isomers have a similar degree of toxicity as mixed xylenes to estuarine/marine invertebrates. ... For m-xylene and p-xylene, the respective 48-hour LC50 values are 19.3 and 24.5 mg/L in brine shrimp ... , suggesting that the m-xylene and p-xylene isomers are slightly toxic to estuarine/marine invertebrates on an acute basis.[U.S. EPA Office of Prevention, Pesticides and Toxic Substances; Environmental Fate and Ecological Risk Assessment for the Reregistration of Xylene Range Aromatic Solvents p.39 (October 4, 2005) EPA Docket No. EPA HQ-OPP-2006-0145-0002

For more Ecotoxicity Excerpts (Complete) data for 4-XYLENE (6 total), please visit the HSDB record page.

5.60e+02

2.40e+03

1.00e+02

4.40e+02

1.90e+02

2.00e+00

1.90e-01

2.00e-01

1.00e-01

Volatile

3.90e+02

1.70e+03

7.30e+03

3.10e+02

1.30e+03

5.80e+02

The substance is toxic to aquatic organisms.

4-Xylene's production and use in the synthesis of terephthalic acid for polyester resins and fibers and in the manufacture of vitamins, pharmaceuticals, and insecticides may result in its release to the environment through various waste streams. 4-Xylene may be released into the environment through emissions from petroleum refining, through the use of gasoline and diesel engines, and through leaks and evaporation losses during the transport and storage of gasoline and other fuels. It is emitted to air from burning wood and in motor vehicle exhaust. The compound is a component of coal tar and gasoline. 4-Xylene occurs naturally in petroleum and is released during forest fires and occurs in various plants. If released to air, a vapor pressure of 8.84 mm Hg at 25 °C indicates 4-xylene will exist solely as a vapor in the atmosphere. Vapor-phase 4-xylene will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals and nitrate radicals; the half-lives for these reaction in air is estimated to be 26 hours and 65 days respectively. 4-Xylene has been detected in rainwater and snow and, therefore, it may be removed from the air by wet deposition. 4-Xylene does not absorb at wavelengths >290 nm and, therefore, is not expected to be susceptible to direct photolysis by sunlight. If released to soil, 4-xylene is expected to have moderate mobility based upon Koc values ranging from 246-540. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 6.90X10-3 atm-cu m/mole. 4-Xylene is expected to volatilize from dry soil surfaces based upon its vapor pressure. 4-Xylene biodegrades in soil and water under both aerobic and anaerobic conditions. Biodegradation is an important process in subsurface soils and groundwater where volatilization is hindered. Utilizing a standard test (manometric respirometry), 90% of the theoretical biodegradation was reached in 4 weeks indicating 4-xylene can be readily biodegradable. However, under anaerobic conditions, a long lag period may be required before degradation commences. If released into water, 4-xylene is expected to adsorb to suspended solids and sediment based upon the Koc values. Volatilization from water surfaces is expected to be an important fate process based upon this compound's Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 3.1 hours and 4.1 days, respectively. BCF values of 15 and 19 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions. Photooxidation may have some importance in surface waters exposed to sunlight. Occupational exposure to 4-xylene may occur through inhalation and dermal contact with this compound at workplaces where 4-xylene is produced or used. Monitoring data indicate that the general population may be exposed to 4-xylene via inhalation of ambient air, inhalation of wood smoke, ingestion of food and drinking water, and dermal contact with consumer products containing 4-xylene. Contact with xylene occurs from a variety of consumer products, including gasoline, paint, varnish, shellac, rust preventives and cigarette smoke. (SRC)

4-Xylene (in combination with the other xylene isomers) occurs naturally in petroleum(1) and is released during forest fires(1,2). 4-Xylene occurs in various plants(3) and is emitted in volatile emissions from corn, alfalfa and cereal silage(4). Mixed xylenes are present in petroleum stocks and natural gas in small quantities(5).

4-Xylene's production and use in the synthesis of terephthalic acid for polyester resins and fibers and in the manufacture of vitamins, pharmaceuticals, and insecticides(1) may result in its release to the environment through various waste streams(SRC). 4-Xylene may be released into the environment through emissions from petroleum refining, through the use of gasoline and diesel engines, and through leaks and evaporation losses during the transport and storage of gasoline and other fuels(2). 4-Xylene is a component of coal tar(2). 4-Xylene is emitted to air from burning wood(3) and in motor vehicle exhaust(4-6).

In a survey of 62 cars, present in exhaust of gasoline engines at 1.9 vol% of emitted hydrocarbons; in exhaust of diesel engines at 1.9% emitted hydrocarbons; in reciprocating gasoline engine at 1.3% of emitted hydrocarbons; and in rotary gasoline engine at 5.6% of emitted hydrocarbons. /m- and p-xylene/

TERRESTRIAL FATE: Based on a classification scheme(1), Koc values ranging from of 204-540(2-4), indicate that 4-xylene is expected to have moderate to low mobility in soil(SRC). Volatilization of 4-xylene from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 6.90X10-3 atm-cu m/mole(5). 4-Xylene is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 8.84 mm Hg at 25 °C(6). Biodegradation is an important fate process under acclimated conditions(7) and in subsurface soils and groundwater where volatilization is hindered(8). 4-Xylene is expected to biodegrade in soil under both aerobic and anaerobic conditions(8) and has been observed to biodegrade in standard biodegradability tests using various inocula(9). For example, using OECD Guideline 301F (Ready Biodegradability: Manometric Respirometry Test) with a mixture of sewage, soil and natural water inoculum, 4-xylene reached 90% of its O2 consumption in 28 days which classified 4-xylene as readily biodegradable(9). Biodegradation proceeds more slowly under anaerobic conditions as is evidenced by about 50% removal of 4-xylene after several months using nitrate-amended soil column(10). Under anaerobic conditions, a long lag period may be required before xylene degradation commences(11).

AQUATIC FATE: Based on a classification scheme(1), Koc values ranging from 204-540(2-4), indicate that 4-xylene may adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(5) based upon a Henry's Law constant of 6.90X10-3 atm-cu m/mole(6). Using this Henry's Law constant and an estimation method(5), volatilization half-lives for a model river and model lake are 3.1 hours and 4.1 days, respectively(SRC). According to a classification scheme(7), a BCF values of 15(8)and 19(9), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation is an important process in groundwater where volatilization is hindered(10). 4-Xylene has been observed to biodegrade in standard biodegradability tests using various inocula(11). For example, using OECD Guideline 301F (Ready Biodegradability: Manometric Respirometry Test) with a mixture of sewage, soil and natural water inoculum, 4-xylene reached 90% of its O2 consumption in 28 days which classified 4-xylene as readily biodegradable(11). However, under anaerobic conditions, a long lag period may be required before xylene degradation commences(12). Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions(5). Irradiation studies using humic substances(13) suggest photooxidation of xylene may have some environmental importance in natural surface waters exposed to sunlight(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 4-xylene, which has a vapor pressure of 8.84 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase 4-xylene is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 26 hours(SRC), calculated from its rate constant of 1.43X10-11 cu cm/molecule-sec at 25 °C(3). Vapor-phase 4-xylene is degraded slowly in the atmosphere by reaction with night-time nitrate radicals(SRC); the half-life for this reaction in air is estimated to be 65 days(SRC), calculated from its rate constant of 4.53X10-16 cu cm/molecule-sec at 25 °C(4). 4-Xylene has been detected in rainwater and snow(5,6), and therefore, it may be removed from the air by wet deposition(SRC). 4-Xylene does not absorb at wavelengths >290 nm(7) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

AEROBIC: In general, it has been found that 4-xylene is biodegraded in soil and groundwater samples under aerobic conditions(1). Using a standard BOD dilution technique and a sewage inoculum, a 44% of theoretical BOD was observed over a 5 day incubation period(2). Over 88% of an initial influent concentration of 24.0 ug/L was biodegraded by an activated sludge plant treating municipal wastewater(3) over a 5 day operation period. A jet fuel acclimated aquifer mineralized 70-80% of a 4-xylene sample under denitrifying conditions over a 55 day incubation period(4). A coarse sand aquifer removed 52-100% of 4-xylene from contaminated groundwater under natural aerobic conditions over a 13 day incubation period(5). A 0.15 mM sample of 4-xylene was completely degraded in a diesel fuel acclimated aquifer during an 11 day incubation period(6). Complete biodegradation of a groundwater sample of 4-xylene, 85 ug/L, in an activated sand aquifer was observed within 110 days(7). The degradation rate constant for 4-xylene in an activated sand aquifer was measured as 0.038/day(7). The degradation rate constant of 4-xylene measured in the Columbus Air Force Base aquifer, Columbus, MS was 0.0107/days(8). Xylene (mixed isomers), present at 100 mg/L, reached 100% of its theoretical BOD in 4 weeks using an activated sludge inoculum at 30 mg/L in the Japanese MITI test which classified xylene as readily biodegradable(9). Using OECD Guideline 301F (Ready Biodegradability: Manometric Respirometry Test) with non-adapted activated sludge inoculum, 4-xylene (41 mg/L) reached 68% of its theoretical BOD in 10 days and 87.8% in 28 days which classified 4-xylene as readily biodegradable(10). In a different OECD Guideline 301F study using a mixture of sewage, soil and natural water inoculum, 4-xylene reached 90% of its O2 consumption in 28 days which classified it as readily biodegradable(10). 3-/4-Xylene, present at 50 mg/L, reached 85% of its theoretical BOD in 14 days during a 28-day BOD test(11).

AEROBIC: An activated sludge inoculum obtained from a Wisconsin wastewater treatment facility biodegraded a 5.53 ug/L sample of 3-/4-xylene(1). Aerobic flow-through aquifer column studies resulted in 80% removal of combined 3-/4-xylene(2). Combined 3-/4-xylene concentrations were not significantly reduced within 42 days following the addition of nitrate to this column; however, anaerobic conditions in the nitrate-amended column resulted in about 50% removal of 3- and 4-xylene after several months(2). Groundwater contaminated with combined 3-/4-xylene (at 1,300 ug/L) was treated with both upflow aerated columns and rotating biological contactors with 98% removal in 37 days and 96% removal in 146 days, respectively(3). 98.1% of the combined 3-/4-xylene present initially was biodegraded in an activated sludge treatment plant(4).

ANAEROBIC: In general, it has been found that 4-xylene may be degraded under anaerobic denitrifying conditions(1). Biodegradation of 4-xylene was observed under anaerobic denitrifying conditions(2). Combined 3-/4-xylene concentration was not significantly reduced within 42 days following the addition of nitrate to a soil column; however, anaerobic conditions in the nitrate-amended column resulted in about 50% removal of 3-/4-xylene after several months(3). Leachate containing 3-/4-xylene at 100 ug/L was significantly biodegraded under denitrifying conditions but not under either iron-reducing or methanogenic conditions(4). Anaerobic microcosms were constructed using aquifer sediment and groundwater from the Seal Beach Naval Weapons Station in CA which had been contaminated with gasoline(5). Following the loss of toluene, 3-/4-xylenes was biodegraded completely by day 39 with a maximum rate of 4.1 ug/L-hr(5). Following the addition of nitrate, there was less complete removal of 3-/4-xylene; however, the maximum removal rate was increased to 5.4 ug/L-hr(5). In an anaerobic microcosm inoculated with sediment and groundwater from a polluted iron-reducing aquifer, 4-xylene was degraded by the intrinsic bacteria under iron-reducing conditions(6).

The rate constant for the vapor-phase reaction of 4-xylene with photochemically-produced hydroxyl radicals has been estimated as 1.43X10-11 cu cm/molecule-sec at 25 °C(1). This corresponds to an atmospheric half-life of about 26 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(2). The rate constant for the vapor-phase reaction of 4-xylene with night-time nitrate radicals is 4.53X10-16 cu cm/molecule-sec at 25 °C(3). This corresponds to an atmospheric half-life of about 65 days at an atmospheric concentration of 2.5X10+8 nitrate radicals per cu cm(4). The rate constant for the vapor-phase reaction of 4-xylene with ozone is 1.36X1-21 cu cm/molecule-sec at 25 °C(3). This corresponds to an atmospheric half-life of about 23 years at an atmospheric concentration of 7X10+11 ozone molecules per cu cm(2). Products from the gas-phase reaction of nitrate with 4-xylene were 4-methylbenzaldehyde and 4-methylbenzyl nitrate(5). 4-Xylene is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(6). 4-Xylene, at 30 mg/L in water, does not absorb at wavelengths >290 nm(7) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC). Negligible absorption above 290 nm has also been reported for 4-xylene(8).

The photolysis of jet fuel JP-4 in water resulted in the degradation of 3-/4-xylene combined, from 1.46 to 1.38 to 1.34 to 1.20 mg/L in 0, 7, 14, and 21 days, respectively, in pond water(1).

Experimental BCF values of 15(1,2) and 19(3) have been reported for fish for 4-xylene. Rainbow trout (Oncorhynchus mykiss) exposed to xylene (emulsified in aquatic weed control) for 56 days in a flow-through system had a maximum BCF of 25.9(4). According to a classification scheme(5), these BCF values suggest the potential for bioconcentration in aquatic organisms is low(SRC).

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

Generators of waste (equal to or greater than 100 kg/mo) containing this contaminant, EPA hazardous waste number U239 and F003, must conform with USEPA regulations in storage, transportation, treatment and disposal of waste.

Product: Burn in a chemical incinerator equipped with an afterburner and scrubber but exert extra care in igniting as this material is highly flammable. Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material; Contaminated packaging: Dispose of as unused product.

p-Xylene is a waste chemical stream constituent which may be subjected to ultimate disposal by controlled incineration.

Xylene is a waste chemical stream constituent which may be subjected to ultimate disposal by controlled incineration.

/GUIDE 130 FLAMMABLE LIQUIDS (Non-Polar/Water-Immiscible/Noxious)/ Fire or Explosion: HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water. /Xylenes/

/GUIDE 130 FLAMMABLE LIQUIDS (Non-Polar/Water-Immiscible/Noxious)/ Health: May cause toxic effects if inhaled or absorbed through skin. Inhalation or contact with material may irritate or burn skin and eyes. Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution. /Xylenes/

/GUIDE 130 FLAMMABLE LIQUIDS (Non-Polar/Water-Immiscible/Noxious)/ Public Safety: CALL Emergency Response Telephone Number on Shipping Paper first. If Shipping Paper not available or no answer, refer to appropriate telephone number listed on the inside back cover. As an immediate precautionary measure, isolate spill or leak area for at least 50 meters (150 feet) in all directions. Keep unauthorized personnel away. Stay upwind. Keep out of low areas. Ventilate closed spaces before entering. /Xylenes/

/GUIDE 130 FLAMMABLE LIQUIDS (Non-Polar/Water-Immiscible/Noxious)/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Structural firefighters' protective clothing will only provide limited protection. /Xylenes/

For more DOT Emergency Guidelines (Complete) data for 4-XYLENE (8 total), please visit the HSDB record page.

UN 1307; Xylenes

IMO 3; Xylenes

49 093 51; Xylenes

No person may /transport,/ offer or accept a hazardous material for transportation in commerce unless that person is registered in conformance ... and the hazardous material is properly classed, described, packaged, marked, labeled, and in condition for shipment as required or authorized by ... /the hazardous materials regulations (49 CFR 171-177)./

The International Air Transport Association (IATA) Dangerous Goods Regulations are published by the IATA Dangerous Goods Board pursuant to IATA Resolutions 618 and 619 and constitute a manual of industry carrier regulations to be followed by all IATA Member airlines when transporting hazardous materials. Xylenes is included on the dangerous goods list. /Xylenes/

The International Maritime Dangerous Goods Code lays down basic principles for transporting hazardous chemicals. Detailed recommendations for individual substances and a number of recommendations for good practice are included in the classes dealing with such substances. A general index of technical names has also been compiled. This index should always be consulted when attempting to locate the appropriate procedures to be used when shipping any substance or article. Xylenes is included on the dangerous goods list. /Xylenes/

Flammable Liquid

UN Hazard Class: 3; UN Pack Group: III