Substance profile
Styrene Oxide
Styrene Oxide is a colorless to pale straw-colored liquid with a sweet, pleasant odor.
01 · Identification
What Styrene Oxide is
Styrene Oxide is a colorless to pale straw-colored liquid with a sweet, pleasant odor. Its molecular formula is C8H8O and its molecular weight is 120.15 g/mol. It boils at 194 °C, melts at -35.6 °C.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
Styrene Oxide identifiers and molecular data
Styrene Oxide CAS number and EC number
Styrene Oxide molecular formula and molecular weight
Other names for Styrene Oxide
- (epoxyethyl)benzene
- phenyloxirane
03 · GHS classification
Styrene Oxide hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Styrene Oxide pictograms and signal word
Styrene Oxide hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - dermal GHS chapter 3.1 | Category 4 | H312 | GHS07 |
| Serious eye damage/eye irritation GHS chapter 3.3 | Category 2A | H319 | GHS07 |
| Carcinogenicity GHS chapter 3.6 | Category 1A or 1B | H350 | GHS08 |
Where two values are shown with “or”, the hazard statement is shared by more than one category or by more than one class, and the code alone does not say which. H272, for example, belongs to oxidising liquids and to oxidising solids — the physical state decides. The binding answer for a specific entry is in the CLP Annex VI table itself.
Styrene Oxide hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H350 | May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>. |
| H312 | Harmful in contact with skin. |
| H319 | Causes serious eye irritation. |
This page lists only the codes assigned to Styrene Oxide. The full reference lives on the hazard statements hub, the precautionary statements hub and the GHS pictograms hub.
Safety Data Sheet
Getting an SDS for Styrene Oxide
A Safety Data Sheet is written for a product, not for a substance: the supplier of the grade you actually buy issues it, so two suppliers of Styrene Oxide issue two different sheets. That is why there is no single authoritative SDS for a substance to download — what there is, is the job of collecting the sheets for the products you hold and keeping them current as suppliers revise them.
04 · Precautionary statements
Styrene Oxide precautionary statements
CLP Annex VI assigns 11 precautionary statements to Styrene Oxide. They are grouped the way a label groups them: what to do before handling, what to do when something has already happened, how to store it and how to dispose of it.
Prevention
What to do before and during handling so the hazard never happens.
Response
What to do once exposure, spillage or fire has already happened.
Reading the notation. … is a blank the supplier fills in — not a truncated sentence.· [square brackets] mark a part printed only when it applies.
05 · Names in the regulation
Styrene Oxide name in 23 EU languages
CLP Annex VI Part 3 is published in every language edition of the regulation, and the identification column is written out in each of them. Nothing below is translated by us: each line is the name as that edition prints it. Under Art. 18(2) the substance name from Annex VI is a lawful product identifier, so this is the wording to put on a label going to that market — and where the cell lists several designations, any one of them qualifies.
| Language | Name in CLP Annex VI Part 3 |
|---|---|
| Bulgarian български | стиреноксид (епоксиетил)бензенфенилоксиран |
| Spanish español | Óxido de estireno (epoxietil)bencenofeniloxirano |
| Czech čeština | styrenoxid (epoxyethyl)benzenfenyloxiran |
| Danish dansk | styrenoxid (epoxyethyl)benzenphenyloxiran |
| German Deutsch | Styroloxid (Epoxyethyl)benzolPhenyloxiran |
| Estonian eesti | stüreenoksiid (epoksüetüül)benseenfenüüloksiraan |
| Greek ελληνικά | οξείδιο του στυρολίου (εποξυαιθυλο)βενζόλιοφαινυλοξιράνιο |
| English English | styrene oxide (epoxyethyl)benzenephenyloxirane |
| French français | oxyde de styrène (époxyéthyl)benzènephényloxirane |
| Croatian hrvatski | stiren-oksid (epoksietil)benzenfeniloksiran |
| Italian italiano | stirene ossido (epossietil)benzenefenilossirano |
| Latvian latviešu | stirola oksīds (epoksietil)benzolsfeniloksirāns |
| Lithuanian lietuvių | stireno oksidas (epoksietil)benzenasfeniloksiranas |
| Hungarian magyar | sztirol-oxid (epoxietil)benzolfeniloxirán |
| Maltese Malti | ossidu tal-istiren (epossietil)benzenfenilossiran |
| Dutch Nederlands | styreenoxide (epoxyethyl)benzeenfenyloxiraan |
| Polish polski | tlenek styrenu (epoksyetylo)benzenfenylooksiran |
| Portuguese português | óxido de estireno (epoxietil)benzenofeniloxirano |
| Romanian română | oxid de stiren (epoxietil)benzenfeniloxiran |
| Slovak slovenčina | styrén oxid oxiranylbenzénfenyloxirán |
| Slovenian slovenščina | stiren oksid (epoksietil)benzenfeniloksiran |
| Finnish suomi | styreenioksidi (epoksietyyli)bentseenifenyylioksiraani |
| Swedish svenska | styrenoxid (epoxietyl)bensenfenyloxiran |
All 23 language editions of Annex VI carry this entry. Irish is the twenty-fourth official EU language and has no line here for a different reason: no consolidated CLP text has ever been published in Irish, so there is no Irish edition of Annex VI to quote a name from. Source: consolidated CLP, CELEX 02008R1272, language editions. © European Union, https://eur-lex.europa.eu — only the electronic Official Journal of the European Union is authentic.
06 · Label elements
Styrene Oxide GHS label elements
Everything CLP Annex VI fixes for Styrene Oxide, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Styrene Oxide
- May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
- Harmful in contact with skin.
- Causes serious eye irritation.
- Obtain special instructions before use.
- Wash … thoroughly after handling.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF ON SKIN:
- IF IN EYES:
- IF exposed or concerned:
- Call a POISON CENTER/doctor/… if you feel unwell.
- Get medical advice/attention.
- If eye irritation persists:
- Remove contact lenses, if present and easy to do. Continue rinsing.
- Wash with plenty of water/…
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Styrene Oxide in the GHS label constructor →
07 · Health hazards
Styrene Oxide health hazards and exposure limits
Styrene Oxide hazard summary
Styrene oxide is used as a reactive plasticizer or diluent for epoxy resins and in the production of phenethyl alcohol and styrene glycol and its derivatives. Acute (short-term) exposure to styrene oxide causes skin and eye irritation in humans. Corneal injury, liver, and neurological effects have been reported in acutely exposed animals. No information is available on the chronic (long-term), reproductive, developmental, or carcinogenic effects of styrene oxide in humans. Maternal toxicity and increased fetal mortality have been observed in rats and rabbits exposed to styrene oxide by inhalation. Several studies have reported an increased incidence of forestomach tumors in rats and mice exposed via gavage (experimentally placing the chemical in the stomach). The International Agency for Research on Cancer (IARC) has classified styrene oxide as a Group 2A, a probable human carcinogen.
Source: EPA Hazardous Air Pollutants
Styrene Oxide carcinogenicity classification
Evaluation: There is inadequate evidence in humans for the carcinogenicity of styrene-7,8-oxide. There is sufficient evidence in experimental animals for the carcinogenicity of styrene-7,8-oxide. Overall evaluation: Styrene-7,8-oxide is probably carcinogenic to humans (Group 2A).
Source: Hazardous Substances Data Bank (HSDB)
Styrene-7,8-oxide: reasonably anticipated to be a human carcinogen.
Source: Hazardous Substances Data Bank (HSDB)
An IARC group and a CLP classification answer different questions. IARC judges whether the evidence for cancer in humans is strong enough; CLP Annex VI is the legally binding EU classification. A substance can carry one and not the other.
08 · Physical and chemical properties
Styrene Oxide properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
Styrene Oxide boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 194.1 °C (381.4 °F) | HSDB | |
| 193.89 °C (381 °F) | at 760 mmHg | CAMEO | |
| 194 °C (381.2 °F) | ICSC |
Styrene Oxide melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -35.6 °C (-32.1 °F) | HSDB | |
| -37.22 °C (-35 °F) | CAMEO | ||
| -36.7 °C (-34.1 °F) | ICSC |
Styrene Oxide density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 1.05 g/cm³ | ICSC | |
| 1.0523 g/cm³ | OSHA | ||
| 1.049 g/cm³ | at 25 °C | HSDB |
Styrene Oxide solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Completely soluble in acetone, benzene, carbon tetrachloride, ethyl ether, heptane, methanol | HSDB | |
| 0.3% wt in water | HSDB | ||
| less than 1 mg/mL at 67.1 °F (NTP, 1992) | at 19.5 °C | CAMEO |
Styrene Oxide vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 0.3 mmHg | at 20 °C | HSDB |
Styrene Oxide flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 73.89 °C (165 °F) | HSDB | |
| 79.44 °C (175 °F) | CAMEO | ||
| 76 °C (168.8 °F) | ICSC |
Styrene Oxide autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 498.33 °C (929 °F) | HSDB | |
| 498 °C (928.4 °F) | ICSC |
Styrene Oxide lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 1.1 % by volume | ICSC |
Styrene Oxide upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 22 % by volume | ICSC |
Styrene Oxide vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 4.3 (air = 1) | HSDB | |
| 4.14 (air = 1) | CAMEO |
Styrene Oxide odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Odor detection in air, 0.063 ppm (purity not specified) | HSDB | |
| Odor recognition in air, 0.400 ppm (purity not specified) | HSDB | ||
| Odor low 0.3093 mg/cu m; Odor high 1.9640 mg/cu m | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Styrene Oxide fire and explosion behaviour
These are descriptions rather than measured values, so they are kept out of the table above and quoted here with the source that reported them.
Styrene Oxide fire potential
On ... basis /of flash point/, it presents hazard of flammability similar to that encountered with ... o-cresol, o-dichlorobenzene, naphthalene, phenol, and dimethylaniline. Definite hazard exists whenever ... /it/ is heated to temperatures at and above the flash point.
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Styrene Oxide storage and handling
Styrene Oxide safe storage
Separated from acids, bases and food and feedstuffs. Ventilation along the floor.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Styrene Oxide storage conditions
... PRECAUTIONS SHOULD BE TAKEN TO PREVENT EXCESSIVE PRESSURE UNDER STORAGE OR REACTION CONDITIONS & TO RELIEVE SUCH PRESSURE SHOULD IT OCCUR.
Source: Hazardous Substances Data Bank (HSDB)
Styrene Oxide incompatible materials
REACTS VIGOROUSLY WITH CMPD HAVING LABILE HYDROGEN, INCL WATER, IN PRESENCE OF CATALYSTS SUCH AS ACIDS, BASES, & CERTAIN SALTS
Source: Hazardous Substances Data Bank (HSDB)
Styrene Oxide reactivity
STYRENE OXIDE is incompatible with oxidizing agents. Also incompatible with acids and bases. Reacts with 4-(4'-nitrobenzyl)pyridine. Polymerizes exothermally and reacts vigorously with compounds possessing a labile hydrogen (e.g. alcohols and amines) in the presence of catalysts such as acids, bases and certain salts (NTP, 1992).
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Styrene Oxide in the storage compatibility matrix →
11 · Transport
Styrene Oxide UN number and transport classification
Transport classification is a separate system from the GHS classification above. It decides how a package is marked and how a load may be carried; it does not follow from the workplace label, and the workplace label does not follow from it. The entries below are linked by CAS number, never by name.
Styrene Oxide under UN 1114 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| BENZENE | 3 | F1 | II | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 3 is “Flammable liquids” (ADR 2.1.1.1).
United States · 49 CFR 172.101 Hazardous Materials Table
| Proper shipping name (column 2) | Class or division | PG | Labels (column 6) |
|---|---|---|---|
| Benzene | 3 | II | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 3 is “Flammable and combustible liquid” (49 CFR 173.2).
12 · Questions
Styrene Oxide — frequently asked questions
What is the CAS number of Styrene Oxide?
The CAS number of Styrene Oxide is 96-09-3. Its EC number is 202-476-7.
What is the chemical formula of Styrene Oxide?
The molecular formula of Styrene Oxide is C8H8O and its molecular weight is 120.15 g/mol.
What does a Styrene Oxide label have to show?
Under CLP Annex VI the label for Styrene Oxide carries the pictograms Health hazard and Exclamation mark and the signal word is Danger.
Is Styrene Oxide flammable?
CLP Annex VI assigns Styrene Oxide no flammability hazard class. That is not a statement that it cannot burn: the harmonised list only records the hazards that were assessed for it. The flash point reported for it is 73.89 °C (165 °F) (HSDB).
Is Styrene Oxide a carcinogen?
Yes. CLP Annex VI classifies Styrene Oxide as a category 1A or 1B carcinogen and assigns it H350: may cause cancer. IARC places it in Group 2A: probably carcinogenic to humans.
What is the boiling point of Styrene Oxide?
The boiling point reported for Styrene Oxide is 194.1 °C (381.4 °F) (HSDB).
What is the melting point of Styrene Oxide?
The melting point reported for Styrene Oxide is -35.6 °C (-32.1 °F) (HSDB).
How should Styrene Oxide be stored?
... PRECAUTIONS SHOULD BE TAKEN TO PREVENT EXCESSIVE PRESSURE UNDER STORAGE OR REACTION CONDITIONS & TO RELIEVE SUCH PRESSURE SHOULD IT OCCUR. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Styrene Oxide
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