Substance profile
Naphthalene
Naphthalene is white crystalline flakes Plates from ethanol with an aromatic odor.
01 · Identification
What Naphthalene is
Naphthalene is white crystalline flakes Plates from ethanol with an aromatic odor. Its molecular formula is C10H8 and its molecular weight is 128.17 g/mol. It boils at 218 °C, melts at 80.2 °C.
Under the GHS it carries the signal word Warning. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
Naphthalene identifiers and molecular data
Naphthalene CAS number and EC number
Naphthalene molecular formula and molecular weight
03 · GHS classification
Naphthalene hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Naphthalene pictograms and signal word
Naphthalene hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - oral GHS chapter 3.1 | Category 4 | H302 | GHS07 |
| Carcinogenicity GHS chapter 3.6 | Category 2 | H351 | GHS08 |
| Hazardous to the aquatic environment - acute GHS chapter 4.1 | Category 1 | H400 | GHS09 |
| Hazardous to the aquatic environment - chronic GHS chapter 4.1 | Category 1 | H410 | GHS09 |
Naphthalene hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H351 | Suspected of causing cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>. |
| H302 | Harmful if swallowed. |
| H400 | Very toxic to aquatic life. |
| H410 | Very toxic to aquatic life with long lasting effects. |
This page lists only the codes assigned to Naphthalene. 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 Naphthalene
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 Naphthalene 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
Naphthalene precautionary statements
CLP Annex VI assigns 11 precautionary statements to Naphthalene. 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.
Disposal
What has to happen to the contents and the empty container.
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
Naphthalene 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 | нафтален |
| Spanish español | Naftaleno |
| Czech čeština | naftalen |
| Danish dansk | naphthalen |
| German Deutsch | Naphthalin |
| Estonian eesti | naftaleen |
| Greek ελληνικά | ναφθαλίνιο |
| English English | naphthalene |
| French français | naphtalène |
| Croatian hrvatski | naftalen |
| Italian italiano | naftalene |
| Latvian latviešu | naftalīns |
| Lithuanian lietuvių | naftalenas |
| Hungarian magyar | naftalin |
| Maltese Malti | naftalen |
| Dutch Nederlands | naftaleen |
| Polish polski | naftalen |
| Portuguese português | naftaleno |
| Romanian română | naftalin |
| Slovak slovenčina | naftalén |
| Slovenian slovenščina | naftalen |
| Finnish suomi | naftaleeni |
| Swedish svenska | naftalen |
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
Naphthalene GHS label elements
Everything CLP Annex VI fixes for Naphthalene, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Warning
Naphthalene
- Suspected of causing cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
- Harmful if swallowed.
- Very toxic to aquatic life.
- Very toxic to aquatic life with long lasting effects.
- Obtain special instructions before use.
- Do not eat, drink or smoke when using this product.
- Avoid release to the environment.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF SWALLOWED:
- IF exposed or concerned:
- Call a POISON CENTER/doctor/… if you feel unwell.
- Get medical advice/attention.
- Rinse mouth.
- Collect spillage.
- Dispose of contents/container to …
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Naphthalene in the GHS label constructor →
07 · Health hazards
Naphthalene health hazards and exposure limits
Naphthalene hazard summary
Naphthalene is used in the production of phthalic anhydride; it is also used in mothballs. Acute (short- term) exposure of humans to naphthalene by inhalation, ingestion, and dermal contact is associated with hemolytic anemia, damage to the liver, and neurological damage. Cataracts have also been reported in workers acutely exposed to naphthalene by inhalation and ingestion. Chronic (long-term) exposure of workers and rodents to naphthalene has been reported to cause cataracts and damage to the retina. Hemolytic anemia has been reported in infants born to mothers who "sniffed" and ingested naphthalene (as mothballs) during pregnancy. Available data are inadequate to establish a causal relationship between exposure to naphthalene and cancer in humans. EPA has classified naphthalene as a Group C, possible human carcinogen.
Source: EPA Hazardous Air Pollutants
Naphthalene carcinogenicity classification
Under the conditions of this 2-year inhalation study, there was clear evidence of carcinogenic activity of naphthalene in male and female F344/N rats based on increased incidences of respiratory epithelial adenoma and olfactory epithelial neuroblastoma of the nose.
Source: US National Toxicology Program · TR-500: Toxicology and Carcinogenesis Studies of Naphthalene (CASRN 91-20-3) in F344/N Rats (Inhalation Studies) (2000 )
Evaluation: There is inadequate evidence in humans for the carcinogenicity of naphthalene. There is sufficient evidence in experimental animals for the carcinogenicity of naphthalene. Overall evaluation: Naphthalene is possibly carcinogenic to humans (Group 2B).
Source: Hazardous Substances Data Bank (HSDB)
Naphthalene is reasonably anticipated to be a human carcinogen based on sufficient evidence from studies in experimental animals.
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.
Naphthalene occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 10.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 10 ppm (50 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| PEL | TWA 10 ppm (50 mg/m3) See Appendix G | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 10 ppm (50 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| REL | 15 ppm (75 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| REL | TWA 10 ppm (50 mg/m3) ST 15 ppm (75 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 250 ppm (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 250 ppm [From NPG: Naphthalene] (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 250.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
These are United States values. The European Union sets its own indicative and binding limits, and the figure that applies at a given workplace is the one in the local regulation — not the one shown here.
08 · Physical and chemical properties
Naphthalene 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.
Naphthalene boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 217.9 °C (424.2 °F) | HSDB | |
| 217.78 °C (424 °F) | NIOSH | ||
| 217.78 °C (424 °F) | at 760 mmHg | CAMEO |
Naphthalene melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 80.2 °C (176.4 °F) | HSDB | |
| 80 °C (176 °F) | NIOSH | ||
| 80.22 °C (176.4 °F) | CAMEO |
Naphthalene density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 1.15 g/cm³ | NIOSH | |
| 1.162 g/cm³ | at 20 °C | HSDB |
Naphthalene solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | 0.003% | NIOSH | |
| In water, 31 mg/L at 25 °C | at 25 °C | HSDB |
Naphthalene vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 0.08 mmHg | NIOSH | |
| 0.05 mmHg | at 20 °C | CAMEO | |
| 0.085 mmHg | at 25 °C | HSDB |
Naphthalene flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 79 °C (174.2 °F) | Closed cup | HSDB |
| 78.89 °C (174 °F) | NIOSH | ||
| 87.78 °C (190 °F) | CAMEO |
Naphthalene autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 526.11 °C (979 °F) | HSDB | |
| 540 °C (1004 °F) | ICSC |
Naphthalene lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 0.9 % by volume | HSDB |
Naphthalene upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 5.9 % by volume | HSDB |
Naphthalene vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 4.42 (air = 1) | HSDB |
Naphthalene odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Odor detection in water 6.80 ppm (purity not specified) | HSDB | |
| At least as low as 0.3 ppm. | HSDB | ||
| Odor threshold (water) 0.021 mg/L (w/v); odor threshold (air) 0.084 ppm (v/v) | HSDB |
Naphthalene critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 475.22 °C (887.4 °F) | HSDB | |
| Critical pressure: 588 PSI = 40.0 atm = 4.05 megaNewtons/sq m | HSDB |
Naphthalene corrosivity
| Property | Value | Conditions | Source |
|---|---|---|---|
| Corrosivity | Melted naphthalene will attack some forms of plastics, rubber, and coatings. | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Naphthalene 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.
Naphthalene fire potential
Flammable in the presence of a source of ignition, through friction or retained heat.
Source: Hazardous Substances Data Bank (HSDB)
Solubility
1 g/13 mL ethanol or methanol; 1 g/3.5 mL benzene or toluene; 1 g/8 mL olive oil or tupentine; 1 g/2 mL chloroform or carbon tetrachloride; 1 g/1.2 mL carbon disulfide. Very soluble in ether, hydronaphthalenes, and in fixed and volatile oils.
Source: HSDB
10 · Handling and storage
Naphthalene storage and handling
Naphthalene safe storage
Separated from strong oxidants and food and feedstuffs. Store in an area without drain or sewer access. Provision to contain effluent from fire extinguishing.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Naphthalene storage conditions
Without inert-gas blanketing and at the temperature normally used for the storage of molten naphthalene, i.e., 90 °C, the vapors above the liquid are within the flammability limits. Thus, storage tanks containing molten naphthalene have a combustible mixture in the vapor space and care must be taken to eliminate all sources of ignition around such systems. Naphthalene dust can form explosive mixtures with air which necessitates the design and operation of solid handling systems.
Source: Hazardous Substances Data Bank (HSDB)
Naphthalene incompatible materials
Naphthalene ...will react violently with chromic anhydride.
Source: Hazardous Substances Data Bank (HSDB)
Naphthalene reactivity
Vigorous reactions, sometimes amounting to explosions, can result from the contact between aromatic hydrocarbons, such as NAPHTHALENE, and strong oxidizing agents. They can react exothermically with bases and with diazo compounds. Substitution at the benzene nucleus occurs by halogenation (acid catalyst), nitration, sulfonation, and the Friedel-Crafts reaction. Naphthalene, camphor, glycerol, or turpentine will react violently with chromic anhydride [Haz. Chem. Data 1967. p 68]. Friedel-Crafts acylation of naphthalene using benzoyl chloride, catalyzed by AlCl3, must be conducted above the melting point of the mixture, or the reaction may be violent [Clar, E. et al., Tetrahedron, 1974, 30, 3296].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Naphthalene in the storage compatibility matrix →
11 · Transport
Naphthalene 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.
The same CAS number is shipped under more than one UN number. Which entry applies follows from the form and the concentration of the consignment — read the proper shipping name, not the CAS.
Naphthalene under UN 1334 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| NAPHTHALENE, CRUDE or NAPHTHALENE, REFINED | 4.1 | F1 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 4.1 is “Flammable solids, self-reactive substances, polymerizing substances and solid desensitized explosives” (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) |
|---|---|---|---|
| Naphthalene, crude or Naphthalene, refined | 4.1 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 4.1 is “Flammable solid” (49 CFR 173.2).
Naphthalene under UN 2304 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| NAPHTHALENE, MOLTEN | 4.1 | F2 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 4.1 is “Flammable solids, self-reactive substances, polymerizing substances and solid desensitized explosives” (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) |
|---|---|---|---|
| Naphthalene, molten | 4.1 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 4.1 is “Flammable solid” (49 CFR 173.2).
12 · Questions
Naphthalene — frequently asked questions
What is the CAS number of Naphthalene?
The CAS number of Naphthalene is 91-20-3. Its EC number is 202-049-5.
What is the chemical formula of Naphthalene?
The molecular formula of Naphthalene is C10H8 and its molecular weight is 128.17 g/mol.
What does a Naphthalene label have to show?
Under CLP Annex VI the label for Naphthalene carries the pictograms Exclamation mark, Health hazard and Environment and the signal word is Warning.
Is Naphthalene flammable?
CLP Annex VI assigns Naphthalene 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 79 °C (174.2 °F), Closed cup (HSDB).
Is Naphthalene a carcinogen?
CLP Annex VI assigns Naphthalene H351 — suspected of causing cancer. That is category 2: the evidence points that way but is not conclusive. IARC places it in Group 2B: possibly carcinogenic to humans.
What is the exposure limit for Naphthalene?
The US occupational exposure limit reported for Naphthalene is 10.0 [ppm] (Haz-Map, Information on Hazardous Chemicals and Occupational Diseases). Limits differ by country: the EU sets its own indicative and binding values, and the figure that applies at a given workplace is the one in the local regulation.
What is the boiling point of Naphthalene?
The boiling point reported for Naphthalene is 217.9 °C (424.2 °F) (HSDB).
What is the melting point of Naphthalene?
The melting point reported for Naphthalene is 80.2 °C (176.4 °F) (HSDB).
How should Naphthalene be stored?
Without inert-gas blanketing and at the temperature normally used for the storage of molten naphthalene, i.e., 90 °C, the vapors above the liquid are within the flammability limits. Thus, storage tanks containing molten naphthalene have a combustible mixture in the vapor space and care must be taken to eliminate all sources of ignition around such systems. Naphthalene dust can form explosive mixtures with air which necessitates the design and operation of solid handling systems. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Naphthalene
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