M-Xylene

log Kow = 3.20

3.20

3.37

Sweet odor

Aromatic odor

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

0.8698 g/cu cm at 25 °C

Critical density: 2.66 mmol/cu m; Critical volume: 376.0 cu m/mol

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

0.8598 @25 °C

0.86

0.581 mPa.s at 25 °C

0.58 mPa*s at 25 °C

Clear, colorless liquid

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

Insoluble (NTP, 1992)

In water, 1.61X10+2 mg/L at 25 °C.

In water, 160 mg/L at 25 °C (average of 13 literature values ranging from 134-206 mg/L at 25 °C)

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

Solubility in water, g/l at 25 °C: 0.174 (very slightly soluble)

Slight

85 °F (NTP, 1992)

25.0 °C (77.0 °F) - closed cup

77 °F (25 °C) (closed cup)

25 °C c.c.

82 °F

Warning

H226: Flammable liquid and vapor [Warning Flammable liquids]

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 1386) of reports.

Danger

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

Chemical: Benzene, 1,3-dimethyl-

Benzene, 1,3-dimethyl- is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Benzene, 1,3-dimethyl- are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)

Status: Active Update: 06-10-2021 https://echa.europa.eu/registration-dossier/-/registered-dossier/14230

Benzene, 1,3-dimethyl-: HSNO Approval: HSR001236 Approved with controls

The New Jersey Worker and Community Right to Know Act requires public and private employers to provide information about hazardous substances at their workplaces. (N.J.S.A. 34:5A-1 et. seq.)

Behavior in Fire: Vapor is heavier than air and may travel considerable distance to a source of ignition and flash back. (USCG, 1999)

Flammable. Above 25 °C explosive vapour/air mixtures may be formed.

Vapors cause headache and dizziness. Liquid irritates eyes and skin. If taken into lungs, causes severe coughing, distress, and rapidly developing pulmonary edema. If ingested, causes nausea, vomiting, cramps, headache, and coma; can be fatal. Kidney and liver damage can occur. (USCG, 1999)

A skin and eye irritant; May have CNS effects; An aspiration hazard by ingestion; May have adverse effects on human reproduction or development, based on animal studies; [ICSC] May cause smarting and reddening of skin if spilled and allowed to remain on clothes; High vapor concentrations may cause mild smarting of eyes and respiratory system; May cause liver and kidney injury; [CHRIS] A local irritant; Inhalation of high concentrations may cause narcotic effects, severe coughing, and pulmonary edema; Ingestion may cause kidney and liver injury; [NTP] A skin and strong eye irritant; Harmful by inhalation and skin absorption; May cause narcosis, lung irritation, chest pain, pulmonary edema, CNS depression, blood disorders, liver and kidney injury, and reproductive disorders; [Sigma-Aldrich MSDS] See Xylene isomers.

The major hazards encountered in the use and handling of 3-xylene stem from its toxicologic properties and flammability. Exposure to this clear, colorless sweet-smelling liquid may occur from its use as a chemical intermediate, as a component of gasoline, and as an industrial solvent. Toxic by all routes of exposure (ie, dermal, ingestion, and inhalation), 3-xylene can cause effects including headache, dizziness, skin and eye irritation, kidney and liver damage, pulmonary edema, coma, and death. The ACGIH recommends a workplace exposure limit (TLV) of 100 ppm as an 8-hr time-weighted average (TWA); however, to assure protection, wear an approved canister or air-supplied mask, face shield, plastic gloves, and boots and use non-sparking tools when handling 3-xylene. In emergency situations, a self-contained breathing apparatus and full protective clothing are recommended. If contact does occur, immediately flush exposed eyes with running water, wash exposed skin with soap and water, and remove contaminated clothing. Individuals with diseases of the central nervous system, liver, kidneys, and blood should be protected from exposure. 3-Xylene is easily ignitable by heat, sparks, or flame (flash point: 25 °C, closed cup) and may do so explosively in an enclosed area. Also, vapor may travel a considerable distance to a source of ignition and flash back. The heat of a fire may cause containers to explode and/or cause thermal degradation of 3-xylene, producing acrid smoke and toxic gases. Fires involving 3-xylene may be extinguished with dry chemical, CO2, water spray, fog, or foam. For massive fires in enclosed areas, use unmanned hose holders or monitor nozzles. If a 3-xylene tank car or truck is involved in a fire, isolate 1/2 mile in all directions. Runoff from fire control water may cause pollution, and, upon entering a sewer, may create an explosion hazard. Storage of 3-xylene is preferably in outdoor or detached areas, away from heat, any sources of ignition, oxidizing agents, and any activity that could cause physical damage to containers. For small spills of 3-xylene, take up with sand or other non-combustible absorbent and place in containers for later disposal, or absorb on paper and evaporate in an appropriate exhaust hood. In either case, take care to avoid contact with the liquid or vapor. For large spills, isolate the area, dike far ahead of the spill and collect the material for disposal. 3-Xylene is a good candidate for the Belliot process of oxidative destruction, as well as liquid injection, rotary kiln, and fluidized bed incineration. 3-Xylene may be sent to a solvent disposal company, but prior to implementing any land disposal of waste residue (including waste sludge), consult regulatory agencies for guidance.

WHO; Environmental Health Criteria 190: Xylenes (1997)[Available from, as of July 19, 2016: http://www.inchem.org/documents/ehc/ehc/ehc190.htm]

US EPA; Toxicological Reviw of Xylenes (CAS No. 1330-20-7) In Support of Summary Information on the Integrated Risk Information System (IRIS)(January 2003).[Available from, as of July 29, 2016: https://www.epa.gov/iris]

American Chemistry Council Benzene, Toluene, and Xylenes VCCEP Consortium; Xylenes Category: m-Xylene (CAS No. 108-38-3), o-Xylene (CAS No. 95-47-6), p-Xylene (CAS No. 106-42-3), Mixed Xylenes (CAS No. 1330-20-7) Voluntary Children's Chemical Evaluation Program (VCCEP) Tier 1 Pilot Submission Docket Number OPPTS - 00274D October 6, 2005. With Appendix A - Xylenes Exposure (60 pp), Appendix B -Xylenes Robust Summaries (75 pp.) and Appendix C - Xylenes PBPK Modeling (PDF) (34 pp.).[Available from, as of July 19, 2016: https://java.epa.gov/chemview]

U.S. EPA Risk Assessment Division, OPPTS; Voluntary Childrens Chemical Evaluation Program: Data Needs Assessment of Xylenes. 19 pp. (March 2007).[Available from, as of July 19, 2016: https://java.epa.gov/chemview]

For more Special Reports (Complete) data for 3-XYLENE (10 total), please visit the HSDB record page.

F003; When xylene is a spent solvent, it is classified as a hazardous waste from a nonspecific source (F003), as stated in 40 CFR 261.31, and must be managed according to State and/or Federal hazardous waste regulations. /Xylenes/

U239; As stipulated in 40 CFR 261.33, when xylene, as a commercial chemical product or manufacturing chemical intermediate or an off-specification commercial chemical product or a manufacturing chemical intermediate, becomes a waste, it must be managed according to Federal and/or State hazardous waste regulations. Also defined as a hazardous waste is any residue, contaminated soil, water, or other debris resulting from the cleanup of a spill, into water or on dry land, of this waste. Generators of small quantities of this waste may qualify for partial exclusion from hazardous waste regulations (40 CFR 261.5). /Xylenes/

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

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

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.

(General first aid procedures)

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]

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.

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. Storage class (TRGS 510): Flammable liquids.

Protect containers against physical damage. Outdoor or detached storage is preferable. Indoor storage should be in a standard flammable liquid storage room.

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. Evacuate personnel to safe areas. 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.

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.

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.

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.

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.

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.

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. Evacuate personnel to safe areas. 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.

Appropriate engineering controls: Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday.

For more Preventive Measures (Complete) data for 3-XYLENE (8 total), please visit the HSDB record page.

... m-Xylene ... /was/ detected in brain, liver, lung, vitreous fluid, kidney, and blood of two individuals who died from exposure to painting sprays by packed and open tubular gas chromatography and mass spectroscopy.

The mean concentration of 3-/4-xylene was 0.21 ng/mL in the blood of 134 school-age children that participated in the School Health Initiative: Environment, Learning, Disease (SHIELD) study in Minneapolis, MN(1). The mean concentration of 3-/4-xylene was 0.32 ng/mL in the blood of 43 children living in an inner city neighborhood of Minneapolis, MN(2). A median measured personal 3-/4-xylene concentration of 4.4 ug/cu m was determined for participants of the BEAM study which included 55 individuals employed in nonmanufacturing workplaces, including schools and offices, and living in suburban or urban locations in the greater Boston, MA area(3).

Expired air samples from 54 normal, healthy volunteers from an urban population in Chicago, IL had mean levels of 3-xylene of 0.0003 mg/cu m(1). Expired air samples from urban residents of two New Jersey cities had a mean value of 0.009 mg/cu m for combined 3-/4-xylene. Levels were higher in persons who pumped their own gasoline or were exposed to auto and truck exhaust(1). Blood samples collected from a reference group of a non-occupationally exposed US population contained combined 3-/4-xylene at a mean concentration of 0.37 ppb (median = 0.19, n = 649)(2). 100% of expired air samples from 26 smokers and 43 non-smokers contained 3-/4-xylene, combined(3). Expired air samples collected from 28 healthy human subjects contained 3-xylene at a mean concentration of 0.35 ng/L(4). Expired air samples collected from 54 healthy human subjects contained 3-xylene at a mean concentration of 0.324 ng/L (15.8% positive samples)(5). 100% of human adipose tissue samples collected for the National Human Adipose Tissue Survey, contained xylene, unspecified isomer, with wet tissue concentrations of 0.4-400 ng/g; the greatest concns were found in the South Atlantic region for people 15-45+ years of age(6).

The reported mean concentration of 3-/4-xylene measured in the personal air of 36 high school students in New York City participating in the TEACH study was 10.9 ug/cu m in the summer and 6.71 ug/cu m in the winter(1).

Personal air samples collected from 340 residents fall 1981, 150 residents in summer 1982, and 49 residents from Elizabeth-Bayonne NJ in winter 1983 contained 3-/4-xylene combined, at average concns of 52, 37, and 36 ug/cu m, respectively, for 12 hour samples. Personal air samples collected from 110 Los Angeles, CA residents in winter 1984, 50 Los Angeles, CA residents in spring 1984, and from Contra Costa, CA residents in summer 1984 contained 3-/4-xylene, combined, at average concns of 18, 12, and 5.5 ug/cu m, respectively, for 12 hour samples(1).

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.

Ingestion of ethanol (0.8 g/kg) prior to exposure to m-xylene (6.0 or 11.5 mmol/cu m) produced a marked alteration in xylene kinetics. Blood xylene level rose and urinary methylhippuric acid excretion decreased suggesting ethanol decreased metab clearance of xylene by about one-half.

Healthy male subjects were exposed at weekly intervals to m-xylene concn of 6 umol/L (145 ppm) and 11.5 umol/L (290 ppm) for 4 hr alone and in combination with prior ingestion of single doses of alcohol (0.8 g/kg). Body sway was recorded with a strain gauge transducer platform with the subject's eyes closed and open, and the eyes closed/open ratio, indicating the grade of visual compensation for body balance. Alcohol with xylene concn of 11.5 umol/L significantly incr the ratio, a finding suggesting an unexpected combined effect of xylene and alcohol, possibly of metabolic origin, on the human equilibrium system.

The metabolic interaction and disposition of methyl ethyl ketone and m-xylene after single or multiple inhalation exposures were studied in rats. Male Wistar-rats were exposed one for 6 hr to 300 ppm m-xylene or 600 ppm methyl ethyl ketone vapor alone or in combination. Other rats were exposed to 600 ppm methyl ethyl ketone and 300 ppm m-xylene, separately or together, daily for 7 days. They were then given a final exposure 18 hr later. The rats were killed 0.5 or 18 hr after the last exposure and the blood and perirenal fat /were taken and analyzed for xylene and MEK. The livers were/ removed and assayed for 7-ethoxycoumarin-O-deethylase, 7-ethoxyresorufin-O-deethylase, and 7-pentoxyresorufin-O-deethylase. Urine samples collected from other animals were analyzed for methyl-hippuric acid, 2,4-dimethylphenol, and thioethers. Blood m-xylene concentrations were slightly, significantly increased in rats exposed to the mixture compared to those exposed to xylene only. Blood methyl ethyl ketone concentrations were not significantly affected by xylene. Blood xylene concentrations were similar in rats given the single and multiple exposures. Perirenal fat m-xylene concn in rats exposed to the mixture were significantly higher than in those exposed to xylene alone 0.5 and 18 hr after exposure ended. Xylene concentrations were significantly lower after the multiple exposure than after the single exposure. Fat methyl ethyl ketone concentrations were also increased by coexposure to m-xylene. Methyl-hippuric acid excretion was decreased and 2,4-dimethylphenol excretion increased in rats exposed to the mixture relative to those exposed to m-xylene only. All m-xylene exposed rats showed sharp increase in urinary thioether excretion. Thioether excretion in controls. Multiple exposures to xylene significantly increased hepatic 7-ethoxycoumarin-O-deethylase, 7-ethoxyresorufin-O-deethylase, and 7-pentoxyresorufin-O-deethylase activity. Methyl ethyl ketone caused only a slight increase in activity of these enzymes. The combined exposures caused a synergistic increase in 7-pentoxyresorufin-O-deethylase activity and an additive increase in 7-ethoxyresorufin-O-deethylase and 7-ethoxycoumarin-O-deethylase activity. The authors conclude that methyl ethyl ketone inhibits the metabolism of xylene by suppressing side chain oxidation, but not oxidation of the aromatic ring.

The present study was undertaken to investigate the mechanism of toxicokinetic interaction between toluene and m-xylene in vivo in the male Sprague-Dawley rat by physiologically based toxicokinetic modeling. First, the metabolic constants (Vmax and Km) were determined for toluene and m-xylene individually by conducting a series of closed-chamber inhalation exposures of three rats to starting concn of 500 to 4000 ppm. The values of Km (toluene, 0.55 mg/L; m-xylene, 0.20 mg/L) and Vmax (toluene, 4.8 mg/hr/kg; m-xylene, 8.4 mg/hr/kg) were obtained following best visual fit of physiologically based toxicokinetic model simulations to experimental data. Then using the same experimental set-up, rats were exposed to three different mixtures of both solvents (500 ppm toluene + 1000 ppm m-xylene; 1000 ppm toluene + 1000 ppm m-xylene; 1000 ppm toluene + 500 ppm m-xylene). The data from the time course of chamber solvent concn were analyzed with a binary chemical mixture physiologically based toxicokinetic model that had four mechanistic hypotheses of metabolic interaction (i.e., no interaction, competitive inhibition, noncompetitive inhibition, and uncompetitive inhibition) quantitatively defined in the liver compartment. The validity of the various model descriptions was verified with open-chamber inhalation exposure data on toxicokinetics of toluene and m-xylene. Overall, the results of this combined experimental and modeling approach are consistent with a competitive metabolic inhibition between m-xylene and toluene in the rat.

For more Interactions (Complete) data for 3-XYLENE (15 total), please visit the HSDB record page.

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.

LC50; Species: Cancer magister (Crab) larvae-stage I; Concentration: 12 ppm for 96 hr /Conditions of bioassay not specified/

LC50; Species: Crangon franciscorum (Shrimp); Concentration: 3.7 ppm for 96 hr /Conditions of bioassay not specified/

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

EC50; Species: Pseudokirchneriella subcapitata (Green algae); Conditions: freshwater, static; Concentration: 4900 ug/L for 72 hr; Effect: growth, general /formulated product/

For more Ecotoxicity Values (Complete) data for 3-XYLENE (14 total), please visit the HSDB record page.

TERRESTRIAL FATE: Based on a classification scheme(1), Koc values ranging from 166-275(2-4), indicate that 3-xylene is expected to have moderate mobility in soil(SRC). Volatilization of 3-xylene from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 7.18X10-3 atm-cu m/mole(5). 3-Xylene is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 8.29 mm Hg at 25 °C(6). 3-Xylene is expected to biodegrade in soil under both aerobic and anaerobic conditions(7). Biodegradation is an important process in subsurface soils and groundwater where volatilization is hindered(7). 3-Xylene has been observed to biodegade in standard biodegradability tests using various inocula(8). For example, using OECD Guideline 301F (Ready Biodegradability: Manometric Respirometry Test) with a mixture of sewage, soil and natural water inoculum, 3-xylene reached 98% of its O2 consumption in 28 days which classified 3-xylene as readily biodegradable(8). 3-Xylene, present in soil samples contaminated with jet fuel, was completely degraded aerobically within 5 days(9), suggesting that biodegradation may be an important environmental fate process in soil(SRC). In anaerobic aquifer studies, 3-xylene was degraded, usually within several weeks(10). However, 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 166-275(2-4), indicate that 3-xylene is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(5) based upon a Henry's Law constant of 7.18X10-3 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 of 14.8 measured in goldfish(8) suggest the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation is an important process in groundwater where volatilization is hindered(9). 3-Xylene has been observed to biodegade in standard biodegradability tests using various inocula(10). For example, using OECD Guideline 301F (Ready Biodegradability: Manometric Respirometry Test) with a mixture of sewage, soil and natural water inoculum, 3-xylene reached 98% of its O2 consumption in 28 days which classified 3-xylene as readily biodegradable(10). However, under anaerobic conditions, a long lag period may be required before xylene degradation commences(11). 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(12) suggest photooxidation 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), 3-xylene, which has a vapor pressure of 8.29 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase 3-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 17 hours(SRC), calculated from its rate constant of 2.31X10-11 cu cm/molecule-sec at 25 °C(3). Vapor-phase 3-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 138 days(SRC), calculated from its rate constant of 2.32X10-16 cu cm/molecule-sec at 25 °C(4). 3-Xylene has been detected in rainwater and snow(5,6) and, therefore, it may be removed from the air by wet deposition(SRC). 3-Xylene does not absorb at wavelengths >290 nm(7) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

3-Xylene was measured in Korean salt-fermented fish and shrimp pastes; big eyed herring, hair-tail viscera, and shrimp pastes had concentrations of 378, 124, and 99.9 ng/g 3-xylene, respectively(1). Volatile flavor components from Idaho Russet Burbank baked potatoes(2), roasted filberts(3), scrambled eggs(4), tree-ripened nectarines(10) and chicken, beef, and pork volatiles(12) contained 3-xylene. 64 of 234 table-ready food items from the FDA's Total Diet Study contained 3- and 4-xylene (reported as a combined value) with the highest concentration found in margarine (114 ppb), butter (54.8 ppb), cake doughnuts (35.0 ppb), and sandwich cookies (12.9 ppb)(5). 3-Xylene was detected in lipid fractions from raw beef(6). 3-/4-Xylene, combined value, was not detected in samples of animal milk from suburban, countryside and pasteurized sources (unreported detection limit)(7). 3-Xylene was detected in the aroma concentrate of cured beef and cured chicken at 0.04 and 0.11 mg/kg, respectively(8). 3-/4-Xylene, combined value, was detected in floured chickpea seed(9). Volatile components of water-boiled duck meat, duck fat, Cantonese style roasted duck, and Cantonese style roasted duck gravy contained 3-xylene at 0.99, 4.29, 9.61, and 18.09 ppb, wet basis, respectively(6).

As part of the US FDA Total Diet Program, monitoring of 70 foods between 1996 and 2000 detected 3-/4-xylene in the following food items(1):[Table#418]

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)

IDENTIFICATION AND USE: 3-Xylene (m-xylene) is a clear colorless liquid. It is used as a solvent; intermediate for dyes and organic synthesis, especially isophthallic acid; in insecticides; in aviation fuel. m-Xylene is also used in the manufacturing of polyester and alkyl resins. HUMAN EXPOSURE AND TOXICITY: The effects of exposure to m-xylene on the central nervous system were investigated in humans. Male volunteers were exposed to m-xylene vapor, at stable concentration of 8.2 umol/L or fluctuating concentration with peaks (16.4 umol/L) for 4 hr a day. Body balance of subjects was clearly impaired in the anteroposterior direction, especially when subjects closed their eyes during the peaks at rest. Body balance improved when subjects exercised, even in the presence of the high m-xylene concn in the blood. Complex motor reactions were impaired after the peaks combined with exercise. In other experiment volunteers exposed to m-xylene were subjected to tests of numerical ability, reaction time, short-term memory and critical flicker fusion. There was evidence of reduction in the performance on 3 of the 4 tests in the second set of experiments. Slight, but statistically significant, increases in the average rating for subjective symptoms of neurological effects were observed following exposure to 50 ppm m-xylene vapor compared to controls. After 60 and 118 minutes of exposure, severity ratings for feelings of intoxication were elevated in men and women, and ratings for headache were elevated in men. The ratings for dizziness were increased in exposed men after 118 minutes of exposure. For biomonitoring purposes the m-and p-xylene isomers usually are measured together and reported as m/p-xylene. ANIMAL STUDIES: Exposure of rats to 2000 ppm of m-xylene for 3 days increased hepatic cytochrome P450 concentration and reduced nicotinamide adenine dinucleotide cytochrome c reductase activity. Adverse respiratory effects noted in rats, mice, and guinea pigs following acute and intermediate inhalation exposure to m-xylene are similar to those observed in humans. They include decreased respiration, labored breathing, irritation of the respiratory tract, pulmonary edema, pulmonary hemorrhage, and pulmonary inflammation. In a study of levels of noradrenaline and dopamine in various parts of the forebrain and hypothalamus, rats (six males/group) were exposed to 0 or 2000 ppm m-xylene, 6 hr/day for 3 days. The animals were killed within 18 hr after the last exposure. A significant increase in catecholamine levels and turnover was observed in various parts of the hypothalamus of exposed animals. There was no effect on dopamine levels. 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. No effect on absolute or relative heart weights was observed in male rats intermittently exposed to m-xylene at concentrations as high as 100 ppm for 13 weeks. Exposure of rats to 1 mg/L of m-xylene, 4 hr/day for 6 months caused inhibition of the phagocytic activity of leukocytes. Mice were exposed to m-xylene at 150, 1500, or 3000 mg/cu m, 24 hr/day from days 7-14 of gestation. Toxic effects were decreased weight of fetuses, decreased activity of succinic dehydrogenase, alkaline and acid phosphatase, and glucose 6-phosphatase. Also m-xylene changed characteristic features of functional maturity of the nephron, retardation of fetus was dose related. At highest dose level it increased preimplantation fetal losses, increased incidence of extra ribs and interfered with process of implantation. The o- and p- isomers appeared more hazardous to the offspring than did the m-isomer. 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. In an Ames assay, m-xylene 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.

m-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.

F003; When xylene is a spent solvent, it is classified as a hazardous waste from a nonspecific source (F003), as stated in 40 CFR 261.31, and must be managed according to State and/or Federal hazardous waste regulations. /Xylenes/

U239; As stipulated in 40 CFR 261.33, when xylene, as a commercial chemical product or manufacturing chemical intermediate or an off-specification commercial chemical product or a manufacturing chemical intermediate, becomes a waste, it must be managed according to Federal and/or State hazardous waste regulations. Also defined as a hazardous waste is any residue, contaminated soil, water, or other debris resulting from the cleanup of a spill, into water or on dry land, of this waste. Generators of small quantities of this waste may qualify for partial exclusion from hazardous waste regulations (40 CFR 261.5). /Xylenes/

Pursuant to section 8(d) of TSCA, EPA promulgated a model Health and Safety Data Reporting Rule. The section 8(d) model rule requires manufacturers, importers, and processors of listed chemical substances and mixtures to submit to EPA copies and lists of unpublished health and safety studies. m-Xylene is included on this list. Effective date 10/4/82; Sunset date: /10/4/92.

Listed as a hazardous air pollutant (HAP) generally known or suspected to cause serious health problems. The Clean Air Act, as amended in 1990, directs EPA to set standards requiring major sources to sharply reduce routine emissions of toxic pollutants. EPA is required to establish and phase in specific performance based standards for all air emission sources that emit one or more of the listed pollutants. 3-Xylene is included on this list.

Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 1000 lb or 454 kg. The toll free number of the NRC is (800) 424-8802. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b).

m-Xylene is designated as a hazardous substance under section 311(b)(2)(A) of the Federal Water Pollution Control Act and further regulated by the Clean Water Act Amendments of 1977 and 1978. These regulations apply to discharges of this substance. This designation includes any isomers and hydrates, as well as any solutions and mixtures containing this substance.

Excretion of m-xylene from most tissues takes place rapidly (elim half-time about 0.5-1.0 hr within 1st hours).

In volunteers exposed to m-xylene the urinary excretion of m-methylbenzoic acid was described as triphasic with half-times of 1-2, 10 and 20 hr. The observed elimination half-time in the subcutaneous adipose tissue was about 58 hr.

Generally in animals, the metabolism of xylenes is similar to that of humans but there are some qualitative differences. The major difference is in the metabolism of methylbenzoic acid ... . Metabolism of xylenes may be influenced by prior exposure. Rats pretreated with m-xylene showed an approximately 10% increase in the percentages of methylhippuric acid and thio ethers in urine. Gastric intubation of rats with 1.1-1.4 mL/kg of m-xylene for 3 consecutive days was found to induce CYP2B and CYP2E1 in liver microsomes. In the Wistar rat, 4 days of inhalation of xylene at 4 g/cu m, 20 hours/day, induced CYP2B1 but reduced CYP2E1.

In humans ... exposed to approx 0.2-0.4 mg/L xylene isomers (o-, m-, p-xylene) or 1:1:1 mixt for up to 8 hr ... Pulmonary retention was 64%, which was ... independent of dosage or duration of exposure. After exposure, only 5% of retained xylenes were elim in expired air. More than 95% ... excreted by humans into urine in form of methylhippuric acids. ... Small portion ... excreted into urine as corresponding xylenols.

The ortho, meta, and para isomers, in decreasing order, are demethylated to phenol. In the rabbits exposed to 1 mg/L, 4 hr/day for 32 days, m-xylene produced 57.3 to 63.9 mg of m-methylhippuric acid. The metabolite was completely cleared 24 hr following exposure.

Meta & para isomers are ... Extensively oxidized to toluic acids (about 90% of the dose), & these are conjugated mostly with glycine. Hydroxylation to corresponding xylenols also occurs to small extent.

For more Metabolism/Metabolites (Complete) data for 3-XYLENE (13 total), please visit the HSDB record page.

M-xylene has known human metabolites that include 2,4-Dimethylphenol and 3-Methylbenzylalcohol.

Xylenes are rapidly absorbed by the respiratory tract with uptake increased by physical exercise. Absorption is also positively correlated with the amount of body fat. Liquid m-xylene is well absorbed through the skin, but dermal absorption of m-xylene vapor (up to 600 ppm) does not appear to be appreciably absorbed. Xylenes are highly soluble in blood and fat, and are distributed widely in the body. Xylenes undergo extensive metabolism and are primarily excreted as metabolites in the urine with small amounts released unchanged in expired air. About 90% of the absorbed dose is excreted in the urine as methylhippuric acid, the glycine conjugate of methylbenzoic acid, following inhalation or dermal (liquid) exposure.

Whole body exposure of mice to 14C-m-xylene vapor for 10 minutes showed that absorption was mainly via respiration. ... Almost complete absorption of 1.8 g m-xylene ...was observed in orally dosed rodents. Absorption after oral administration was rapid and peak levels of m-xylene were seen 20 minutes after a dose of 0.27 mg/kg. After oral administration, absorption rate was faster in females.

Dermal absorption has been studied by in vivo exposure of rat skin to liquid or vapor. Permeability constants were determined and were higher than those for humans. In excised rat skin preparations, duration of exposure correlated with level of skin penetration; rate was 0.967 nmole/sq cm/min. Skin:air partition coefficient for m-xylene was 50.4+/-1.7 and this correlated with the permeability constant.

In rats and mice, m- and p-xylene are distributed primarily to lipid-rich tissues, such as fat, blood, and brain and also in organs highly perfused with blood such as kidney and liver. Small amounts of p-xylene and o-xylene cross the placenta and distribute to amnionic fluid and fetal tissue. Oral administration of m-xylene to rats led to distribution of 14C-m-xylene in adipose tissue, approximately 0.3% of dose in female and 0.1% in males.

For more Absorption, Distribution and Excretion (Complete) data for 3-XYLENE (31 total), please visit the HSDB record page.

Permitted for use as an inert ingredient in non-food pesticide products; [EPA] Found in coal tar; Commercial xylene is a mixture of the o-, m-, and p- isomers with the m-isomer predominating; Used as a solvent, to make dyes, and to sterilize catgut; [Merck Index] Used as a solvent and to make polyester and alkyd resins, insecticides, aviation fuel, and dyes; [HSDB]

Painting (Solvents) [Category: Paint]

Solvent; intermediate for dyes and organic synthesis, especially isophthallic acid; insecticides; aviation fuel.

Most of the MX /3-xylene/ that is contained in recovered mixed xylenes is isomerized to PX /4-xylene/ and OX /2-xylene/. MX is also used to produce isophthalic acid and isophthalonitrile.

m-Xylene is used in the manufacturing of polyester and alkyl resins.

Used as a chemical intermediate for the synthesis of 5-t-butyl-m-xylene; 3,5-di-(trifluoromethyl)aniline; isophthalic acid; isophthalodinitrile; 3-(trifluoromethyl)-benzoyl fluoride; 3,5-xylenol; 2,4-xylidine; 2,6-xylidine.

(1978) 1.26X10+10 G

(1982) 1.02X10+9 G

(1986) 7.62X10+5 gal

2023: 85,000,000 - <100,000,000 lb

1,3-Dimethylbenzene is listed as a High Production Volume (HPV) chemical (65FR81686). Chemicals listed as HPV were produced in or imported into the U.S. in >1 million pounds in 1990 and/or 1994. The HPV list is based on the 1990 Inventory Update Rule. (IUR) (40 CFR part 710 subpart B; 51FR21438).

Production volumes for non-confidential chemicals reported under the Inventory Update Rule. [Table#421]

Non-confidential 2012 Chemical Data Reporting (CDR) information on the production and use of chemicals manufactured or imported into the United States. Chemical: Benzene, 1,3-dimethyl-. National Production Volume: 317,946,408 lb/yr.

The Mitsubishi Gas-Chemical Company (MGCC) has commercialized a process for separating and producing high purity MX /3-xylene/. In addition to producing MX, this process greatly simplifies the separation of the remaining C8 aromatic isomers. This process is based on the formation of a complex between MX and HF-BF3. MX is the most basic xylene and its complex with HF-BF3 is the most stable. The relative basicities of MX, OX /2-xylene/, PX /4-xylene/, and EB /ethylbenzene/ are 100, 2, 1, and 0.14, respectively. MX of >99% purity can be obtained with the MGCC process with <1% MX left in the raffinate by phase separation of hydrocarbon layer from the complex-HF layer. The latter undergoes thermal decomposition, which liberates the components of the complex.

Xylene is produced primarily by the catalytic reforming of naphtha streams, which are rich in alicyclic hydrocarbons. The aromatic reformate fractions consist mainly of benzene, toluene and mixed xylenes, xylenes representing the largest fraction. The xylene isomers are separated from the reformate by extraction and distillation on the basis of differences in boiling point ... 4-xylene is separated by continuous crystallization or adsorption from the mixed xylenes or isomerized from the 3-xylene/4-xylene distillate; 3-xylene is obtained by selective crystallization or solvent extraction of meta-para mixtures.

Grade: 95% (technical); 99%, 99.9% (research)

Present in high octane gasoline at 12.03 wt%

Wholesale and Retail Trade

Benzene, 1,3-dimethyl-: ACTIVE

The commercial product "mixed xylenes" is a technical product generally containing approximately 40% m-xylene and 20% each of o-xylene, p-xylene, and ethylbenzene, as well as small quantities of toluene ...

Xylenes will enter the atmosphere primarily from fugitive emissions and exhaust connected with their use in gasoline. Industrial sources include emissions from petroleum refining and their use as solvents and chemical intermediates ... The primary source of exposure is from air, especially at occupational sites where xylenes are used and in areas with high traffic. /xylenes/

There are some differences in the composition of commercial xylenes produced from petroleum and from coal-tar. The general composition of xylenes from petroleum is 44% m-xylene, 20% o-xylene, 20% p-xylene and 15% ethylbenzene. The xylenes from coal-tar consists of 45-70% m-xylene, 23% p-xylene, 10-15% o-xylene and 6-10% ethylbenzene. Commercial xylene may also contain small amounts of toluene, trimethylbenzene (pseu documene), phenol, thiophene, pyridine and non-aromatic hydrocarbons and has frequently been contaminated with benzene.

Concentration of 3-xylene in gasoline: 5.6% wt