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CAS 1 record

CAS 123-91-1

CAS 123-91-1 matches 1 EU annex record across Annex II–VI of Regulation 1223/2009.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 123-91-1
CAS 123-91-1PubChem CID 31275

1,4-Dioxane

1,4-Dioxane is a clear liquid that easily dissolves in water. It is used primarily as a solvent in the manufacture of chemicals and as a laboratory reagent; 1,4-dioxane also has various other uses that take advantage of its solvent properties. 1,4-Dioxane is a trace contaminant of some chemicals used in cosmetics, detergents, and shampoos. However, manufacturers now reduce 1,4-dioxane from these chemicals to low levels before these chemicals are made into products used in the home. — Agency for Toxic Substances and Disease Registry (ATSDR)

IUPAC name
1,4-dioxane
Molecular formula
C4H8O2
Molecular weight
88.11 g/mol
Exact mass
88.052429494 Da
XLogP3
-0.3
Topological polar surface area
18.5 Ų
Hydrogen-bond donors
0
Hydrogen-bond acceptors
2
Covalent units
1
Defined stereocentres
0

Also known as

Dioxanep-DioxaneDiethylene ether1,4-Diethylene dioxide1,4-DioxacyclohexaneDioxanTetrahydro-1,4-dioxinTetrahydro-p-dioxin
16 more reported names
Di(ethylene oxide)Diethylene dioxideDioxanneDioxane-1,41,4-DioxanGlycol ethylene etherDioxan-1,4p-DioxanTetrahydro-para-dioxinDioxyethylene etherDioksanDiokanpara-DioxaneDiossano-1,4Dioxaan-1,4Glycolethylenether
Open full PubChem recordPubChem annotations3D structure image
External database identifiers

Evidence from additional scientific databases

NIH PubChem PUG-View
Exact identifier match31275

Attributed physical-property, hazard, environmental and use annotations.

  • First Aid: 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. IMMEDIATELY call a hospital or poison control center even if no symptoms (such as redness or irritation) develop. IMMEDIATELY transport the victim to a hospital for treatment after washing the affected areas.; INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. IMMEDIATELY call a physician and be prepared to transport the victim to a hospital even if no symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop. Provide proper respiratory protection to rescuers entering an unknow Source: CAMEO Chemicals
  • ERG2024, Guide 127 (Dioxane): General First Aid:; · Call 911 or emergency medical service.; · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.; · Move victim to fresh air if it can be done safely.; · Administer oxygen if breathing is difficult.; · If victim is not breathing:; -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.; -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).; -- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.; · Remove and isolate contaminated clothing and shoes.; · For minor skin contact, avoid spreading material on unaffected skin.; · In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.; · For severe burns, immediate medical attention is required.; · Effects of exposure (inhalation, ingestion, Source: Emergency Response Guidebook (ERG)
  • First Aid: (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: Water wash promptly - If this chemical contacts the skin, promptly wash the contaminated skin with water. If this chemical penetrates the clothing, promptly remove the clothing and wash the skin with water. If irritation persists after washing, get medical attention.; Breathing: Respiratory support; Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately. Source: The National Institute for Occupational Safety and Health (NIOSH)
  • Signal: Danger Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • GHS Hazard Statements: H225: Highly Flammable liquid and vapor [Danger Flammable liquids]; H319: Causes serious eye irritation [Warning Serious eye damage/eye irritation]; H335: May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]; H350: May cause cancer [Danger Carcinogenicity] Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • Precautionary Statement Codes: P203, P210, P233, P240, P241, P242, P243, P261, P264+P265, P271, P280, P303+P361+P353, P304+P340, P305+P351+P338, P318, P319, P337+P317, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement) Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • Signal: Danger Source: European Chemicals Agency (ECHA)
  • GHS Hazard Statements: H225 (100%): Highly Flammable liquid and vapor [Danger Flammable liquids]; H319 (100%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]; H335 (> 99.9%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]; H350 (22.3%): May cause cancer [Danger Carcinogenicity]; H351 (76.1%): Suspected of causing cancer [Warning Carcinogenicity] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P203, P210, P233, P240, P241, P242, P243, P261, P264+P265, P271, P280, P303+P361+P353, P304+P340, P305+P351+P338, P318, P319, P337+P317, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement) Source: European Chemicals Agency (ECHA)
  • ECHA C&L Notifications Summary: Aggregated GHS information provided per 1577 reports by companies from 50 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.; 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. Source: European Chemicals Agency (ECHA)
  • Signal: Danger Source: NITE-CMC
  • GHS Hazard Statements: H225: Highly Flammable liquid and vapor [Danger Flammable liquids]; H319: Causes serious eye irritation [Warning Serious eye damage/eye irritation]; H332: Harmful if inhaled [Warning Acute toxicity, inhalation]; 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]; H350: May cause cancer [Danger Carcinogenicity]; H372: Causes damage to organs through prolonged or repeated exposure [Danger Specific target organ toxicity, repeated exposure] Source: NITE-CMC
  • Precautionary Statement Codes: P203, P210, P233, P240, P241, P242, P243, P260, P261, P264, P264+P265, P270, P271, P280, P303+P361+P353, P304+P340, P305+P351+P338, P317, P318, P319, P337+P317, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement) Source: NITE-CMC
  • GHS Hazard Statements: H350: May cause cancer [Danger Carcinogenicity] Source: NITE-CMC
  • Precautionary Statement Codes: P203, P280, P318, P405, and P501 (click each P-code to see the statement) Source: NITE-CMC
  • Health Effects: 1,4-Dioxane for short period of time cause eye and nose irritation at low levels, and severe kidney and liver effects and possibly death at very high levels. For long-term exposure, studies in animals have shown that breathing vapors of 1,4-dioxane, swallowing liquid 1,4-dioxane or contaminated drinking water, or having skin contact with liquid 1,4-dioxane affects mainly the liver and kidneys. Studies in workers did not indicate whether 1,4-dioxane causes cancer, but animal studies suggest that it is a probable human carcinogen. (L1189) Source: Toxin and Toxin Target Database (T3DB)
  • NFPA Health Rating: 2 - Materials that, under emergency conditions, can cause temporary incapacitation or residual injury. Source: Hazardous Substances Data Bank (HSDB)
  • NFPA Fire Rating: 3 - Liquids and solids that can be ignited under almost all ambient temperature conditions. Materials produce hazardous atmospheres with air under almost all ambient temperatures or, though unaffected by ambient temperatures, are readily ignited under almost all conditions. Source: Hazardous Substances Data Bank (HSDB)
  • NFPA Instability Rating: 1 - Materials that in themselves are normally stable but that can become unstable at elevated temperatures and pressures. Source: Hazardous Substances Data Bank (HSDB)
  • Toxicity Summary: IDENTIFICATION AND USE: 1,4-Dioxane is a colorless liquid or solid. It is used as a stabilizer for chlorinated solvents, particularly, 1,1,1-trichloroethane. 1,4-Dioxane is used as a solvent for cellulose acetate, ethyl cellulose, benzyl cellulose, resins, oils, waxes, and fats; in spectroscopic and photometric measurements; and in the pulping of wood. Other uses of 1,4-dioxane include the manufacture of adhesives, cements, deodorant fumigants, cosmetics, drugs, cleaning preparations, magnetic tape, plastic, rubber, insecticides, and herbicides, and as a chemical intermediate, as a polymerization catalyst, in the purification of drugs, and in the extraction of animal and vegetable oils. In the laboratory, it is used in the preparation of histological sections for microscopic examination and as a liquid scintillation counting medium. HUMAN EXPOSURE AND TOXICITY: Short-term inhalation exposure to 1,4-dioxane may cause irritation of the eyes, nose, throat, and lungs. Symptoms of acute exposure include coughing, drowsiness, vertigo, headache, nausea, vomiting, stomach pains, coma, and death. There is a report of a fatal case of acute poisoning by inhalation that led to hepatic and rena Source: Hazardous Substances Data Bank (HSDB)
  • Toxicity Summary: Though the mechanism of toxicity of 1,4-dioxane has not yet been elucidated, it is known that its carcinogenic effects are caused by a non-genotoxic mechanism that is most likely cytotoxic in nature. (L1189, L1881) Source: Toxin and Toxin Target Database (T3DB)
  • Environmental Bioconcentration: Using OECD Guideline 305C (Bioaccumulation: Test for the Degree of Bioconcentration in Fish) with 1 and 10 ppm concentrations 1,4-dioxane, BCF values of 0.2-0.7 were measured using carp (Cyprinus carpio) which were exposed over a 6-week period(1). According to a classification scheme(2), these BCF values suggest the potential for bioconcentration in aquatic organisms is low(SRC). Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: TERRESTRIAL FATE: Based on a classification scheme(1), measured Koc values of 29(2) and 17(3) indicate that 1,4-dioxane is expected to have very high mobility in soil(SRC). Volatilization of 1,4-dioxane from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 4.8X10-6 atm-cu m/mole(4). 1,4-Dioxane is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 38.1 mm Hg at 25 °C(5). A 0% of theoretical BOD using activated sludge in the Japanese MITI test(6) suggests that 1,4-dioxane is not readily biodegradable(SRC). Other screening study results indicate that 1,4-dioxane is resistant to biodegradation and slow to biodegrade(7). Using soil microcosms 1,4-dioxane was not biodegraded within 120 days and, therefore, considered recalcitrant(8). 1,4-Dioxane did not biodegrade in most of 20 environmental samples (rivers waters, soils, activated sludge), but it was degradable in soils collected from drainage areas of a chemical factory within 33 days, presumably due to acclimation(9). Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: AQUATIC FATE: Based on a classification scheme(1), measured Koc values of 29(2) and 17(3) indicate that 1,4-dioxane is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(4) based upon a Henry's Law constant of 4.8X10-6 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 7.3 and 56 days, respectively(SRC). According to a classification scheme(6), a BCF range of 0.2-0.7 measured in carp (Cyprinus carpio)(7) suggests the potential for bioconcentration in aquatic organisms is low(SRC). A 0% of theoretical BOD using activated sludge in the Japanese MITI test(7) suggests that 1,4-dioxane is not readily biodegradable(SRC). Other screening studies have found 1,4-dioxane to be resistant to biodegradation and slow to biodegrade(8) and to be recalcitrant(9). 1,4-Dioxane is considered non-biodegradable under conventional bio-treatment technologies based on results of wastewater treatment monitoring data(10). 1,4-Dioxane is a very weak absorber of UV light(11)and results of aqueous photolysis studies(12) suggest that direct photolyis is not an impor Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 1,4-dioxane, which has a vapor pressure of 38.1 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase 1,4-dioxane 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 33 hours(SRC), calculated from its rate constant of 1.18X10-11 cu cm/molecule-sec at 25 °C(3). 1,4-Dioxane is a very weak absorber of UV light(4). Results of aqueous photolysis studies(5) suggest that direct photolysis is not an important environmental fate process(SRC). Source: Hazardous Substances Data Bank (HSDB)
  • Uses: 1,4-Dioxane is used as a solvent for cellulose acetate, ethyl cellulose, benzyl cellulose, resins, oils, waxes, some dyes, and other organic and inorganic compounds. Source: EPA Hazardous Air Pollutants
  • Sources/Uses: Used as a solvent for cellulose esters, ethers, and other organic chemicals; [ACGIH] Used as a solvent in resins, polymers, oils, waxes, dyes, wood pulping, adhesives, varnishes lacquers, paints, and cosmetics; [HSDB] Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
  • Industrial Processes with risk of exposure: Metal Degreasing [Category: Clean]; Textiles (Fiber & Fabric Manufacturing) [Category: Industry]; Painting (Solvents) [Category: Paint]; Plastic Composites Manufacturing [Category: Industry] Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
  • Uses: Stabilizer in chlorinated solvents. Organic solvent for cellulose acetate, ethyl cellulose, benzyl cellulose, resins, oils, waxes, oil and spirit-soluble dyes, and many other organic as well as some inorganic compounds. Source: Hazardous Substances Data Bank (HSDB)
  • Uses: The largest single use of 1,4-dioxane is the stabilization of 1,1,1-trichloroethane against chemical attack by aluminum. Source: Hazardous Substances Data Bank (HSDB)
  • Uses: Historically, 1,4-dioxane has been used as a stabilizer for the solvent 1,1,1-trichloroethane. However, this use is no longer expected to be important due to the 1990 Amendments to the Clean Air Act and the Montreal Protocol, which mandate the eventual phase-out of 1,1,1-trichloroethane production in the U.S. Source: Hazardous Substances Data Bank (HSDB)
  • Uses: Dioxane is used as a solvent in the formulation of inks, coatings, and adhesives, and as solvent for extracting animal and vegetable oils. As a chemical intermediate, dioxane reaction products are useful as insecticides, herbicides, plasticizers, and monomers. The oxonium complexes of dioxane with salts, mineral acids, halogens, and sulfur trioxide are used as catalysts and as reagents for anhydrous acid reactions, brominations, and sulfonations. In the laboratory, dioxane is useful as a cryoscopic solvent for molecular mass determinations and as a stable reaction medium for diverse reactions. Source: Hazardous Substances Data Bank (HSDB)
  • Uses: For more Uses (Complete) data for 1,4-DIOXANE (8 total), please visit the HSDB record page. Source: Hazardous Substances Data Bank (HSDB)
  • Uses: 1,4-Dioxane is primarily used in solvent applications for the manufacturing sector; however, it is also found in fumigants and automotive coolant. 1,4-Dioxane is a byproduct of the ethoxylation process in cosmetics manufacturing, thus many products on the market today contain 1,4-dioxane in very small amounts. However, some cosmetics, detergents, and shampoos may contain 1,4-dioxane at levels higher than recommended by the FDA for other products. 1,4-Dioxane can also be found in tap water, so human exposure to 1,4-dioxane may also occur during activities such as showering, bathing, and laundering. (L1189, L1880) Source: Toxin and Toxin Target Database (T3DB)

Mapped by: Existing checksum-valid CAS to unique PubChem CID match. Retrieved: 2026-08-31. Open source record

Scientific classifications and hazard annotations provide context and do not replace the market-specific regulatory decision shown above.

Additional source coverage and match status
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NIH PubChem PUG-ViewExact match2026-08-31

A recorded no-match is useful evidence that the source was checked; it is not a claim that the substance does not exist elsewhere.

Retrieved from NIH PubChem on 2026-09-02 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Records for CAS 123-91-1

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How CAS 123-91-1 is used on this site

CAS 123-91-1 is the Chemical Abstracts Service identifier used to pin this page to a specific substance. In the current dataset, 1 EU annex record shares this identifier, which helps you cross-check whether the same substance appears under one regulatory context or several.

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A substance identified by CAS 123-91-1 may appear in multiple EU cosmetic regulation annexes when it is subject to different conditions in different contexts. For example, a substance might be restricted under Annex III with specific conditions, and the same CAS might also appear in Annex IV as an approved colorant under separate entry conditions. Each entry must be reviewed individually.

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