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HuagongsheHuagongshe Chemistry Print Report · For research reference only
HCID 7002Generated: October 27, 2026

1-Methylnaphthalene

MEHYL NAPHTHALENE · dycar mn · tetrosin mnlf · methylnaftalen · Methylphthalene · Methylnaphthalene · methyl-naphthalen · Naphthalene, methyl-

https://huagongshe.com/en/chemical/7002

1-Methylnaphthalene molecular structure

Identifiers & Physical Properties

CAS No.1321-94-4
Molecular formulaC11H10
Average molar mass142.2 g/mol
Monoisotopic mass142.07825032 g/mol
SMILESCc1cccc2ccccc12
InChIKeyQPUYECUOLPXSFR-UHFFFAOYSA-N
PubChem CID7002
ChEMBLCHEMBL383808
ChEBICHEBI:50717
EC No.201-966-8
DTXSIDDTXSID9020877

Chemical & Physical Properties

XLogP3.9
Topological polar surface area0
Hydrogen bond donors0
Hydrogen bond acceptors0
Rotatable bonds0
Heavy atoms11
Formal charge0
Complexity128
LogP (partition coefficient)log Kow of 3.87log Kow = 3.87
Density1.01 at 59.9 °F (NTP, 1992) - Denser than waterwill sink1.0202 at 68 °F (USCG, 1999) - Denser than water1.0202 g/cu cm at 20 °CRelative density (water = 1): 1.021.020-1.0251.0381 (estimate)
Color/FormColorless liquid or oil
Solubilityless than 1 mg/mL at 64 °F (NTP, 1992)less than 1 mg/mL at 70 °F (NTP, 1992)In water, 25.0 mg/L at 25 °CIn water, 25.8 mg/L at 25 °CVery soluble in ethanol and ethersoluble in benzene0.0258 mg/mL at 25 °C
Flash pointgreater than 200 °F (NTP, 1992)180 °F (NTP, 1992)This chemical has a flash point of >93 °C (>200 °F). It is probably combustible.180 °F (82 °C) Closed cup
Boiling point450 to 590 °F at 760 mmHg (NTP, 1992)464 to 469 °F at 760 mmHg (NTP, 1992)244 °C241.00 to 245.00 °C. @ 760.00 mm Hg245 °C241-245 °C229.78°C (estimate)
DecompositionWhen heated to decomposition it emits acrid smoke and irritating fumesWhen heated to decomp it emits acrid smoke and fumes.
Melting point-8 °F (NTP, 1992)-30.43 °CMelting point: -22 °C34°C
Vapor density4.91 (NTP, 1992) - Heavier than airwill sink (Relative to Air)4.91 (Air = 1)Relative vapor density (air = 1): 4.9
Odor thresholdOdor Threshold Low: 0.02 [ppm]Odor threshold = 0.02 ppm at 60 °C (detection)THE ODOR THRESHOLD VALUE OF 1-METHYL NAPHTHALENE DETECTED @ ROOM TEMP & 60 DEG WAS 0.02 PPM.
Vapor pressure23 mmHg at 77 °F31 mmHg at 122 °F38 mmHg at 158 °F (NTP, 1992)0.06 [mmHg]0.02 [mmHg]0.067 mm Hg at 25 °CVapor pressure, Pa at °C: 7.20.067 [mm Hg] @25 °C
Refractive indexIndex of refraction: 1.6170 at 20 °C1.612-1.6181.6085 (estimate)
EWG's Food Scores1
FDA UNIIE987XQ801Y
EPA Substance Registry SystemMethylnaphthalene (1321-94-4)
GHS pictogramGHS08
Signal wordWarning
GHS hazard statementsH373-H302-H336-H319-H411-H335
GHS precautionary statementsP260-P314-P501-P261-P271-P304+P340-P312-P403+P233-P405-P501-P264-P280-P305+P351+P338-P337+P313P-P264-P270-P301+P312-P330-P501
UN transport number3082
TSCA inventory statusTSCA listed
Hazard class9
Packing groupIII
Hazardous substances data1321-94-4(Hazardous Substances Data)

Safety & Regulations

GHS classificationThis chemical does not meet GHS hazard criteria for 2.7% (50 of 1882) of reports.DangerH302 (96.3%): Harmful if swallowed [Warning Acute toxicity, oral]H304 (91.6%): May be fatal if swallowed and enters airways [Danger Aspiration hazard]H411 (14.1%): Toxic to aquatic life with long lasting effects [Hazardous to the aquatic environment, long-term hazard]P264, P270, P273, P301+P316, P301+P317, P330, P331, P391, P405, and P501 (click each P-code to see the statement)Aggregated GHS information provided per 1882 reports by companies from 14 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.Reported as not meeting GHS hazard criteria per 50 of 1882 reports by companies.There are 13 notifications provided by 1832 of 1882 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.
Regulatory informationChemical: Naphthalene, 1-methyl-Chemical: Naphthalene, methyl-Hazard Traits - NeurotoxicityAuthoritative List - ATSDR NeurotoxicantsReport - if used as a fragrance or flavor ingredientCommission Regulation (EC) No 1565/2000 (Repealed by Com. Implementing Reg. (EU) No 872/2012)Naphthalene, 1-methyl- is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Naphthalene, 1-methyl- 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: No longer Valid Update: 08-10-2010 https://echa.europa.eu/registration-dossier/-/registered-dossier/1572
DOT labelClass 9
Fire hazardsThis chemical is probably combustible. (NTP, 1992)This chemical is combustible. (NTP, 1992)Combustible. Above 82 °C explosive vapour/air mixtures may be formed.

Applications & Uses

General Description

Bluish-brown oil or a clear yellow liquid. Coal tar or mothball odor.

Preparation & Synthesis

Preparation

Preparation of 1-Methylnaphthalene The methylnaphthalene fraction with a distillation range of 240-245℃ is separated from the wash oil fraction of the distillation. The methylnaphthalene fraction is cooled to -20℃, and crude 2-methylnaphthalene crystals are separated. The resulting mother liquor is used to extract 1-methylnaphthalene. After sulfonation with 95-98% concentrated sulfuric acid, the unsulfonated oil is separated and removed. Then, water is added for dilution, and 1-methylnaphthalene sulfonic acid crystals are precipitated at 10℃. After filtration of the crystals, they are hydrolyzed with superheated steam at 125-150℃ to remove the aqueous layer, yielding industrial-grade 1-methylnaphthalene with a purity of 85-90%. Repeated sulfonation and hydrolysis of industrial-grade 1-methylnaphthalene 2-3 times can yield 1-methylnaphthalene with a purity greater than 98%. Preparation of 2-Methylnaphthalene The methylnaphthalene fraction with a distillation range of 240–245 °C is separated from the wash oil fraction of the distillation. The methylnaphthalene fraction is cooled to -20 °C to separate crude 2-methylnaphthalene crystals. The crude 2-methylnaphthalene is recrystallized from ethanol or methanol. The obtained crystals are centrifuged and heated to melt and filter to remove impurities, yielding 2-methylnaphthalene with a purity of over 97%.

Fire potentialModerate fire risk.
Health hazardsSYMPTOMS: Exposure to this compound may cause skin irritation. It may also cause photosensitization. The vapors, fumes or direct contact with the solid may be irritating to the eyes. Inhalation of the vapors may produce airway irritation, headache, nausea, weakness and collapse. Long term overexposure has led to corneal changes. Ingestion may lead to systemic poisoning involving the gastrointestinal tract, kidneys and blood-forming tissue. Individuals with erythrocytic glucose-6-phosphate dehydrogenase deficiency may be particularly susceptible to possible hemolytic effects. Individuals with a history of or pre-existing disease in eyes, mucous membranes, skin, blood-forming tissues or blood, liver or lungs may be at greater risk of adverse health effects when exposed to this material.ACUTE/CHRONIC HAZARDS: This compound can cause skin irritation and photosensitization. It may be harmful if inhaled or absorbed through the skin, and may be highly toxic if swallowed. When heated to decomposition this compound emits acrid smoke and fumes. (NTP, 1992)Harmful if inhaled. Liquid causes irritation of the eyes and skin and skin photosensitization. Harmful if swallowed. Chronic exposure may cause liver or kidney damage. (USCG, 1999)
Hazards summaryThere are no studies of humans exposed to 1-methylnaphthalene or 2-methylnaphthalene. [ATSDR ToxFAQs] Minimal Risk Level (oral chronic) = 0.7 mg/kg/day (Resp.)[ATSDR] 1-Methylnaphthalene (1-MN) and 2-Methylnaphthalene (2-MN) are respiratory tract irritants. [ACGIH] See Naphthalene.A skin irritant and photosensitizer[HSDB] May cause skin, eye, and respiratory tract irritationCan cause photosensitization[CAMEO] An irritantCan be absorbed through skin[MSDSonline] Photosensitization not mention in 2007 ACGIH documentation of TLV, nor in ATSDR toxic profilePubMed search by CAS numbers found no records relating to photosensitizationSee 1-Methylnaphthalene and 2-Methylnaphthalene.The major hazards encountered in the use and handling of methylnaphthalene stem from its toxicologic properties. Toxic by all routes (ie, ingestion, inhalation, and skin contact), exposure to this colorless liquid may occur from its use as a general solvent, or as a chemical intermediate in the syntheses of methylnaphthalenesulfonate surfactants and n-((dichlorofluoromethyl)thio)phthalimide insecticides. Effects from exposure may include flushing, sweating, headache, restlessness, confusion, fever, nausea, anorexia, diarrhea, skin irritation and dermatitis, oliguria and anuria, corneal damage, hepatocellular injury, convulsions, coma, and possibly death from acute renal failure in the absence of adequate supportive care. Before implementing land disposal of waste methylnaphthalene, consult with environmental regulatory agencies for guidance.The major hazards encountered in the use and handling of 1-methylnaphthalene stem from its toxicologic properties. Toxic by all routes (ie, ingestion, inhalation, and dermal contact), exposure to this colorless liquid may occur from its use as a general solvent, as a chemical intermediate, or as a dye carrier. Effects from exposure may include flushing, headache, restlessness, fever, nausea, anorexia, diarrhea, skin irritation, corneal damage, oliguria, and anemia, hepatocellular injury, convulsions, and coma. 1-Methylnaphthalene is a moderate fire hazard. When heated to decomposition, this substance emits acrid smoke and fumes. For fires involving 1-methylnaphthalene, extinguish with chemical, CO2, water spray or mist, or foam. Before implementing land disposal of waste 1-methylnaphthalene, consult with environmental regulatory agencies for guidance.
Reactive groupHydrocarbons, Aromatic
Special ReportsSchmeltz I et alvol 3, Polynuclear Aromatic Hydrocarbons. Second International Symposium on Analysis, Chemistry, & Biology. Sept 1977, ISBN 0-89004-241-1: 47-60 (1978). Bioassays of naphthalene for cocarcinogenic activity relation to tobacco carcinogenesis was discussed. /Naphthalene & alkyl naphthalenes/Junk GAGord CS, A Review of Organic Emissions from Combustion Processes. Chemosphere 9 (4): 187-230 (1980). A review of organic emissions from combustion processes.U.S. Dept Health & Human Services/Agency for Toxic Substances Disease RegistryToxicological Profile for Naphthalene, 1-Methylnaphthalene, and 2-Methylnaphthalene (Update) (1995) NTIS# PB/95/264362
FIFRA requirementsAs the federal pesticide law FIFRA directs, EPA is conducting a comprehensive review of older pesticides to consider their health and environmental effects and make decisions about their continued use. Under this pesticide reregistration program, EPA examines newer health and safety data for pesticide active ingredients initially registered before November 1, 1984, and determines whether the use of the pesticide does not pose unreasonable risk in accordance to newer saftey standards, such as those described in the Food Quality Protection Act of 1996. Pesticides for which EPA had not issued Registration Standards prior to the effective date of FIFRA '88 were divided into three lists based upon their potential for human exposure and other factors, with List B containing pesticides of greater concern than those on List C, and with List C containing pesticides of greater concern than those on List D. Methylated naphthalenes is found on List C. Case No: 3088Pesticide type: insecticide, fungicideCase Status: No products containing the pesticide are actively registered. Therefore, we are characterizing the case as "cancelled." Under FIFRA, pesticide producers may voluntarily cancel their registered products. EPA also may cancel pesticide registrations if registrants fail to pay required fees or make/meet certain reregistration commitments, or if EPA reaches findings of unreasonable adverse effects.Active ingredient (AI): methylated naphthalenesAI Status: The active ingredient is no longer contained in any registered products ... cancelled." /Methylated naphthalenes/
Reactivity ProfileMETHYLNAPHTHALENE is incompatible with strong oxidizing agents. It is also incompatible with peroxides and oxygen. (NTP, 1992)1-METHYLNAPHTHALENE is sensitive to heat. Reacts with strong oxidizing agents. Incompatible with oxygen and peroxides (NTP, 1992).
Atmospheric standardsThis action promulgates standards of performance for equipment leaks of Volatile Organic Compounds (VOC) in the Synthetic Organic Chemical Manufacturing Industry (SOCMI). The intended effect of these standards is to require all newly constructed, modified, and reconstructed SOCMI process units to use the best demonstrated system of continuous emission reduction for equipment leaks of VOC, considering costs, non air quality health and environmental impact and energy requirements. Alkyl naphthalenes is produced, as an intermediate or a final product, by process units covered under this subpart. /Alkyl Naphthalenes/
Chemical DangersDecomposes on heating. This produces acrid smoke and irritating fumes.
Fire fightingFires involving this material can be controlled with a dry chemical, carbon dioxide or Halon extinguisher. A water spray may also be used. (NTP, 1992)Fire Extinguishing Agents: Water spray, dry chemical, foam or carbon dioxide (USCG, 1999)Use powder, foam, carbon dioxide.
First aid measuresFresh air, rest.Remove contaminated clothes. 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. Give a slurry of activated charcoal in water to drink. Rest. Refer for medical attention .
First aidEYES: 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 areatake 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 usedif 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)
Safe storageStore in an area without drain or sewer access. Provision to contain effluent from fire extinguishing.
Firefighting HazardsSpecial hazards arising from the substance or mixture: Carbon oxides.
Fire fighting proceduresIf material on fire or involved in fire: Use water in flooding quantities as fog. Solid streams of water may be ineffective. Solid streams of water may spread fire. Use foam, dry chemical, or carbon dioxide. /Methylnaphthalenes, liquid/Wear positive pressure self-contained breathing apparatus when fighting fires involving this material. /Methylnaphthalenes, liquid/Fires involving this material can be controlled with a dry chemical, carbon dioxide or Halon extinguisher. A water spray may also be used.To fight fire use dry chemical, carbon dioxide, water spray or mist, foam.Suitable extinguishing media: For small (incipient) fires, use media such as "alcohol" foam, dry chemical, or carbon dioxide. For large fires, apply water from as far as possible. Use very large quantities (flooding) of water applied as a mist or spraysolid streams of water may be ineffective. Cool all affected containers with flooding quantities of water.Advice for firefighters: Wear self contained breathing apparatus for fire fighting if necessary.
Storage conditionsYou should store this material under ambient temperatures.Conditions for safe storage, including any incompatibilities: 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.
Cleanup methodsIf you spill this chemical, FIRST REMOVE ALL SOURCES OF IGNITION. Then, 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 60-70% ethanol followed by washing with a 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.Environmental considerations: Water spill: Use natural barriers or oil spill booms to limit spill travel. Remove trapped material with suction hoses. /Methylnaphthalenes, liquid/Environmental considerations: Land spill: Dig a pit, pond, lagoon, holding area to contain liquid or solid material. /SRP: If time permits, pits, ponds, lagoons, soak holes, or holding areas should be sealed with an impermeable flexible membrane liner./ Dike surface flow using soil, sand bags, foamed polyurethane, or foamed concrete. Absorb bulk liquid with fly ash, cement powder, or commercial sorbents. /Methylnaphthalenes, liquid/Environmental considerations: Air spill: Apply water spray or mist to knock down vapors. /Methylnaphthalenes, liquid/Accidental Release Measures. Personal precautions, protective equipment and emergency procedures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. 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. Keep in suitable, closed containers for disposal.Control of environmental exposure: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided.
Nonfire spill responseSMALL SPILLS AND LEAKAGE: If you spill this chemical, FIRST REMOVE ALL SOURCES OF IGNITION. Then, 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 60-70% ethanol followed by washing with a 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 under ambient temperatures. (NTP, 1992)
Disposal methodsSRP: Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air qualitypotential migration in air, soil or watereffects on animal, aquatic and plant lifeand conformance with environmental and public health regulations. If it is possible or reasonable use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination.The following wastewater treatment technology has been investigated for naphthalene: Biological treatment. /Naphthalene/Waste treatment methods. Product: This combustible material may be burned in a chemical incinerator equipped with an afterburner and scrubber. 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.
Spillage disposalCollect 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. Do NOT let this chemical enter the environment.
Preventive MeasuresPersonnel protection: Avoid breathing vapors. ... /Methylnaphthalenes, liquid/If material not involved in fire: Keep material out of water sources and sewers. Build dikes to contain flow as necessary. Attempt to stop leak if without undue personnel hazard. /Methylnaphthalenes, liquid/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.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.Gloves must be inspected prior to use. Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands.
TreatmentThere is no know antidote for PAHs. Exposure is usually handled with symptomatic treatment. (L10)
Health effectsPAHs are carcinogens and have been associated with the increased risk of skin, respiratory tract, bladder, stomach, and kidney cancers. They may also cause reproductive effects and depress the immune system. (L10)
Ecotoxicity valuesLC50Species: Salmo trutta (Brown Trout) yearlingConditions: freshwater, static, 10 °C, pH 7.6-8.0, hardness 210-290 mg/L CaCO3, alkalinity 165-200 mg/L CaCO3, dissolved oxygen >50%Concentration: 8400 ug/L for 48 hr /formulation/Species: Pimephales promelas (Fathead minnow)Conditions: staticConcentration: 39 mg/L for 1 hr9 mg/L for 24, 48, 72, 96 hrSpecies: Salmo trutta (Brown trout) yearlingsConcentration: 8.4 mg/L for 48 hrEC50Species: Pseudokirchneriella subcapitata (Green Algae)Concentration: 12000 ug/L for 14 daysEffect: growth, general /formulation/Species: Artemia salina (Brine Shrimp) naupliiConditions: saltwater, static, 20 °CConcentration: 18 mmol/cu m for 24 hr /> or =97% purity/For more Ecotoxicity Values (Complete) data for 1-METHYLNAPHTHALENE (10 total), please visit the HSDB record page.
Environmental fateTERRESTRIAL FATE: Based on a classification scheme(1), Koc values of 2290(2) and 4400(3) for 1-methylnaphthalene and 4350(2) and 8500(3) for 2-methylnaphthalene, indicate that methylnaphthalenes are expected to have slight to no mobility in soil(SRC). Volatilization of methylnaphthalenes from moist soil surfaces is expected(SRC) given Henry's Law constants of 5.14X10-4 and 5.18X10-4 atm-cu m/mole(4) for 1- and 2-methylnaphthalene, respectively. However, adsorption to soil is expected to attenuate volatilization(SRC). Methylnaphthalenes are not expected to volatilize from dry soil surfaces(SRC) based upon vapor pressures of 0.067 mm Hg(5) and 0.055 mm Hg(6) for 1- and 2-methylnaphthalene, respectively. Grab samples of groundwater aquifer soil that had acclimated to creosote wastes containing methylnaphthalene were able to degrade methylnaphthalenes, present at 0.02 to 0.12 ppm, under aerobic conditions at 25 °C in less than a week(7). Unacclimated material from the same aquifer degraded methylnaphthalenes at an average rate of 3.5% per week(7)these studies show that methylnaphthalenes will biodegrade, but is more likely after acclimation(SRC).AQUATIC FATE: Based on a classification scheme(1), Koc values of 2290(2) and 4400(3) for 1-methylnaphthalene and 4350(2) and 8500(3) for 2-methylnaphthalene, indicate that methylnaphthalenes are expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(4) based upon Henry's Law constants of 5.14X10-4 and 5.18X10-4 atm-cu m/mole(5) for 1- and 2-methylnaphthalene, respectively. Using these Henry's Law constants and an estimation method(4), volatilization half-lives for a model river and model lake are 5.5 hours and 5.3 days, respectively(SRC). However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column(SRC). The estimated volatilization half-life from a model pond is 23 to 78 days if adsorption is considered(6). Methylnaphthalenes are not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(4). According to a classification scheme(7), BCF values of 30-1800 in Coho salmon(8), Starry flounder(8) and carp(9), suggest bioconcentration in aquatic organisms is low to very high(SRC), the compound may be metabolized by the organism decreasing the BCF(SRC). The direct photolysis half-life for midday, midsummer sunlight at 40 deg N latitude was predicted to be 22 and 54 h for 1- and 2-methylnaphthalene in water solution, respectively(10). A marine water die-away study with sediment inoculum from Dunstaffnage Bay, Oban, Scotland showed a 92 and 88.5% loss of 1- and 2-methylnaphthalene, respectively, contained in crude oil after 7 days at 20 °C(11).ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 1- and 2-methylnaphthalenes, which have respective vapor pressures of 0.067(2) and 0.055(3) mm Hg at 25 °C, are expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase methylnaphthalenes are degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC)the half-lives for these reactions in air are estimated to be 7 hours(SRC), calculated from rate constants of 5.3X10-11 and 5.23X10-11 cu cm/molecule-sec at 25 °C(4). The respective rate constants for the vapor-phase reaction of 1- and 2-methylnaphthalene with ozone have been measured to be <1.3X10-19 and <4X10-19 cu cm/molecule-sec at 25 °C(5), which corresponds to atmospheric half-lives of about 88 and 29 days at an atmospheric concentration of 7X10+11 molecules per cu cm(SRC). The rate constants for the vapor-phase reaction of methylnaphthalenes with nitrogen pentoxide have been measured to be 4.2X10-17 and 3.3X10-17 cu cm/molecule-sec at 25 °C which corresponds to atmospheric half-lives of about 9.6 and 12 days, respectively, at an atmospheric concentration of 2X10+10 nitrogen pentoxide molecules per cu cm(5). Methylnaphthalenes contain chromophores that absorb at wavelengths >290 nm(6) and, therefore, may be susceptible to direct photolysis by sunlight(SRC).TERRESTRIAL FATE: Based on a classification scheme(1), log Koc values of 2.76-5.78 reported in soil and sediment(2-3) indicate that 1-methylnaphthalene is expected to have slight to no mobility in soil(SRC). Volatilization of 1-methylnaphthalene from moist soil surfaces is expected(SRC) given a Henry's Law constant of 5.14X10-4 atm-cu m/mole(4). However, adsorption to soil is expected to attenuate volatilization(SRC). 1-Methylnaphthalene is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 0.067 mm Hg at 25 °C(5). Utilizing the Japanese MITI test, <5% of the Theoretical BOD was reached in 4 weeks(6) indicating that biodegradation is not an important environmental fate process in soil(SRC). 1-Methylnaphthalene should biodegrade rapidly in soils acclimated to polycyclic aromatic hydrocarbons and at a slower rate in unacclimated soils(SRC).AQUATIC FATE: Based on a classification scheme(1), log Koc values of 2.76-5.78 reported in soil and sediment(2-3) indicate that 1-methylnaphthalene is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(4) based upon a Henry's Law constant of 5.14X10-4 atm-cu m/mole(5). Using this Henry's Law constant and an estimation method(4), volatilization half-lives for a model river and model lake are 5.5 hours and 5.3 days, respectively(SRC). However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column. The estimated volatilization half-life from a model pond is 23-41 days if adsorption is considered(6). 1-Methylnaphthalene is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(4). According to a classification scheme(7), BCF values of 30-810 in Coho salmon(8), Starry flounder(8) and carp(9), suggest bioconcentration in aquatic organisms is low to high, the compound may be metabolized by the organism decreasing the BCF(SRC). The direct photolysis half-life for 1-methylnaphthalene in sunlit waters at midday, midsummer and 40 deg N latitude was predicted to be 22 hr(10). 1-Methylnaphthalene was completely removed within <7-14 days from acclimated groundwater aquifer grab samples(11-12). Unacclimated material from the aquifer degraded 1-methylnaphthalene at an average rate of 3.6% per week(12).ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 1-methylnaphthalene, which has a vapor pressure of 0.067 mm Hg a 25 °C(2) is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase 1-methylnaphthalene 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 7.3 hours(SRC), calculated from its rate constant of 5.3X10-11 cu cm/molecule-sec at 25 °C(3). The rate constant for the vapor-phase reaction of 1-methylnaphthalene with ozone has been reported as <1.3X10-19 cu cm/molecule-sec at 25 °C(3). This corresponds to an atmospheric half-life of >88 days at an atmospheric concentration of 7X10+11 ozone molecules per cu cm(4). The rate constant for the vapor-phase reaction of 1-methylnaphthalene with nitrogen pentoxide has been measured to be 3.3X10-17 cu cm/molecule-sec at 25 °C which corresponds to an atmospheric half-life of about 12 days at an atmospheric concentration of 2X10+10 nitrogen pentoxide molecules per cu cm(3). 1-Methylnaphthalene contains chromophores that absorb at wavelengths >290 nm(5) and, therefore, may be susceptible to direct photolysis by sunlight(SRC).
Food survey valuesMethylnaphthalenes were identified as a volatile component of cassava(1), roasted filberts(2), nectarines(3) and cooked meat (mutton, beef, chicken and pork)(4). Assorted types of lima, pinto, red kidney, black, navy and mung beans, soybeans, split peas and lentils were found to contain methylnaphthalenes at 2.8-49.2 ppb(5).1-Methylnaphthalene was identified as a volatile component of cassava(1), roasted filberts(2) and nectarines(3). Assorted types of lima, pinto, red kidney, black, navy and mung beans, soybeans, split peas and lentils were found to contain 1-methylnaphthalene at 2.8-49.2 ppb(4). Crab (Charybdis feriatus), commonly consumed in Asia, contained 1-methylnaphthalene concentrations of 2.7, 0.8 and 13.1 ug/kg dry weight in meat from legs and claws, body and carapace, respectively(5). 1-Methylnaphthalene was found in the meat of boiled crab (Gerion maritae) and shrimp (Funchalia woodward) caught in the Atlantic Ocean near Namibia in the summer of 1989(6). 1-Methylnaphthalene concentrations in wood smoke flavorings were 11.00, 9.28, 6.78, 81.05 and 21.71 ug/kg in oak, cherry tree, beech, poplar and vine shoots, respectively(7). 1-Methylnaphthalene was detected in five commercial olive pomace oil samples from Spain at 1.17-17.71 ug/kgsamples were collected 2001-2002(8). 1-Methylnaphthalene was detected in 35 milk samples collected from 8 grocery stores in Las Vegas, NV from Jan to Feb 2002concentrations were 0.02-0.86, 0.02-0.34 and 0.02-0.55 ng/mL for whole, 2% and 1% milk, respectively(9).
Adverse effectsACGIH Carcinogen - Not Classifiable.
Exposure routesThe substance can be absorbed into the body by inhalation of its aerosol or vapour and by ingestion.Oral (L10)inhalation (L10)
Milk Concentrations1-Methylnaphthalene was detected in 35 milk samples collected from 8 grocery stores in Las Vegas, NV from Jan to Feb 2002concentrations were 0.02-0.86, 0.02-0.34 and 0.02-0.55 ng/mL for whole, 2% and 1% milk, respectively(1).
Toxicity summaryIDENTIFICATION AND USE: Methylnaphthalene is not registered for current pesticide use in the U.S., but approved pesticide uses may change periodically and so federal, state and local authorities must be consulted for currently approved uses. Methylnaphthalenes are used as chemical intermediates, general solvents and in vitamin K production. HUMAN EXPOSURE AND TOXICITY: Methylnaphthalene is presumably less toxic than naphthalene. The only untoward effects reported in man are skin irritation and skin photosensitization. Individuals with erythrocytic glucose-6-phosphate dehydrogenase deficiency may be particularly susceptible to possible hemolytic effects. ANIMAL STUDIES: Induces the formation of cataracts and causes spleen and kidney damage. Pulmonary alveolar proteinosis was induced in mice given twice weekly dermal applications on their backs of 119 mg/kg methylnaphthalene in acetone for 30 weeks. Control mice treated with acetone showed no signs of pulmonary alveolar proteinosis. The test material was specified as a mixture of 1-methylnaphthalene and 2-methylnaphthalene, but the relative proportions of the two isomers in the mixture were not reported. Gross examination of the lungs of exposed animals revealed multiple, grayish white soft spots or nodules sharply demarcated from the pinkish-white surrounding normal tissue, without specific localizationsuch gross lesions were not found in control lungs. Light microscopy showed the alveoli to be filled with amorphous eosinophilic material, many mononucleated cells with abundant foamy cytoplasm, and many clefts corresponding to cholesterol crystals separating the intra-alveolar materials and the lining cells. Alveolar walls were thickened without prominent fibrosis. Electron microscopy revealed that alveolar spaces contained extracellular membranous material (myelinoid structures) and mononucleated giant cells (balloon cells) containing myelinoid structures, lipid droplets, and amorphous crystals. Terminal bronchioleIDENTIFICATION AND USE: 1-Methylnaphthale is a colorless liquid or oil. It is used in insecticide manufacturingmanufacture of phthalic anhydridesolvent in organic synthesisasphalt and naptha constituent. It is also used as a test substance for the determination of the cetane number of diesel fuels. HUMAN EXPOSURE AND TOXICITY: In contrast to naphthalene, the only reported effects of methylated naphthalene in man are skin irritation and skin photosensitization. Chromosome analyses were carried out in human lymphocytes treated in vitro with 1- and 2-methylnaphthalene in the presence and absence of the mammalian metabolic activation system. Without metabolic activation there was no indication of induction of any significant cytogenetic effect by either compound. With metabolic activation a weak clastogenic effect was apparent at 4 mM 2-methylnaphthalene only and sister chromatid exchange frequencies were significantly increased at each dose of 1- and 2-methylnaphthalene, yet always less than twice the control level. The present observations do not indicate that 1- and 2-methylnaphthalene must be classified as potential genotoxic substances.ANIMAL STUDIES: Pure 1-methylnaphthalene increased the reticulocyte counts in the splenectomized dogs but not the intact dogs. Reticulocyte values remained elevated for 10 days after the fogging ceased. Practical grade 1-methylnaphthalene increased leukocyte counts in intact and splenectomized dogs and neutrophil counts in intact dogs, but pure 1-methylnaphthalene had no effect on these parameters. Methylated naphthalene derivatives resulted in concentration-dependent decrease in pain sensitivity in rats and depression of respiratory rate in mice. 1-Methylnaphthalene may be a weak lung carcinogen in male, but not female, mice. At a carcinogenic dose it dooes not induce overt toxicity for any organs and has no in vivo genotoxicity in the lungs. 1- and 2-Methylnaphthalene were tested quantitatively using S. thyphimurium TA98 andThe ability of PAH's to bind to blood proteins such as albumin allows them to be transported throughout the body. Many PAH's induce the expression of cytochrome P450 enzymes, especially CYP1A1, CYP1A2, and CYP1B1, by binding to the aryl hydrocarbon receptor or glycine N-methyltransferase protein. These enzymes metabolize PAH's into their toxic intermediates. The reactive metabolites of PAHs (epoxide intermediates, dihydrodiols, phenols, quinones, and their various combinations) covalently bind to DNA and other cellular macromolecules, initiating mutagenesis and carcinogenesis. (L10, L23, A27, A32)
Ecotoxicity excerpts/AQUATIC SPECIES/ Methylnaphthalene accumulates in marine species... ./AQUATIC SPECIES/ Radiolabeled methylnaphthalene was taken up from food and water by the blue crab Callinectes sapidus. Of the radioactivity assimilated, more than 50% was in the hepatopancreas, suggesting the site of hydrocarbon metabolism. No evidence found of hydrocarbon storage by any tissues./AQUATIC SPECIES/ In toxicity study of petroleum oils on post-larvae of brown shrimp, grass shrimp, and sheepshead minnow, refined oils were more toxic than crude oils due to presence of naphthalene and alkylnaphthalene, including 1-methylnaphthalene. The different naphthalenes were toxic at levels between 0.08 and 5.1 ppm.
Signs and SymptomsRedness.Redness. Pain.Acute exposure to PAHs causes irritation and inflammation of the skin and lung tissue. (A10)
Ongoing Test StatusEPA has released the first beta version (version 0.5) of the Interactive Chemical Safety for Sustainability (iCSS) Dashboard. The beta version of the iCSS Dashboard provides an interactive tool to explore rapid, automated (or in vitro high-throughput) chemical screening data generated by the Toxicity Forecaster (ToxCast) project and the federal Toxicity Testing in the 21st century (Tox21) collaboration. /The title compound was tested by ToxCast and/or Tox21 assaysClick on the "Chemical Explorer" button on the tool bar to see the data./[USEPAICSS Dashboard ApplicationAvailable from, as of December 8, 2014: http://actor.epa.gov/dashboard/]
TSCA inventory statusTSCA listed
UN transport number3082
Signal wordWarning
GHS pictogramGHS08
Hazard class9
Packing groupIII
GHS hazard statementsH373-H302-H336-H319-H411-H335
GHS precautionary statementsP260-P314-P501-P261-P271-P304+P340-P312-P403+P233-P405-P501-P264-P280-P305+P351+P338-P337+P313P-P264-P270-P301+P312-P330-P501
Hazardous substances data1321-94-4(Hazardous Substances Data)