Substance profile
Formaldehyde
Formaldehyde is a nearly colorless gas with a pungent, suffocating odor.
01 · Identification
What Formaldehyde is
Formaldehyde is a nearly colorless gas with a pungent, suffocating odor. Its molecular formula is CH2O and its molecular weight is 30.026 g/mol. It boils at -19.5 °C, melts at -92 °C.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
Formaldehyde identifiers and molecular data
Formaldehyde CAS number and EC number
Formaldehyde molecular formula and molecular weight
Other names for Formaldehyde
- formalin
- methanal
- HCHO
- Bfv
- F-Gen
- Fannoform
- Floguard 1015
- Fm 282
- Formalith
- Formic Aldehyde
- Formol
- Fyde
- Lysoform
- Methaldehyde
- Methyl Aldehyde
- formaldehyde …%
03 · GHS classification
Formaldehyde hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Formaldehyde pictograms and signal word
Formaldehyde hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - oral GHS chapter 3.1 | Category 4 | H302 | GHS07 |
| Acute toxicity - inhalation GHS chapter 3.1 | Category 1 or 2 | H330 | GHS06 |
| Skin corrosion/irritation GHS chapter 3.2 | Category 1A or 1B or 1C | H314 | GHS05 |
| Skin sensitisation GHS chapter 3.4 | Category 1 or 1A or 1B | H317 | GHS07 |
| Germ cell mutagenicity GHS chapter 3.5 | Category 2 | H341 | GHS08 |
| 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.
Formaldehyde 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>. |
| H341 | Suspected of causing genetic defects <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>. |
| H330 | Fatal if inhaled. |
| H302 | Harmful if swallowed. |
| H314 | Causes severe skin burns and eye damage. |
| H317 | May cause an allergic skin reaction. |
Formaldehyde supplemental EU statements (EUH)
| Code | Statement |
|---|---|
| EUH071 | Corrosive to the respiratory tract. |
This page lists only the codes assigned to Formaldehyde. 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 Formaldehyde
Our own Formaldehyde safety data sheet walks through all sixteen sections of the published data. What it is not is the document an inspector asks for: an SDS is issued for a product by its supplier, so the sheet covering the grade actually standing in your store exists only in that supplier’s version. Collecting those and keeping them current as suppliers revise them is a separate job.
04 · Precautionary statements
Formaldehyde precautionary statements
CLP Annex VI assigns 16 precautionary statements to Formaldehyde. 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
Formaldehyde 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 | формалдехид …% |
| Spanish español | Formaldehído ... % |
| Czech čeština | formaldehyd … % |
| Danish dansk | formaldehyd … % |
| German Deutsch | Formaldehyd … % |
| Estonian eesti | formaldehüüd …% |
| Greek ελληνικά | φορμαλδεΰδη …% |
| English English | formaldehyde … % |
| French français | formaldéhyde à ... % |
| Croatian hrvatski | formaldehid … % |
| Italian italiano | formaldeide … % |
| Latvian latviešu | formaldehīds, … % |
| Lithuanian lietuvių | … % formaldehidas |
| Hungarian magyar | formaldehid …% |
| Maltese Malti | formaldeid … % |
| Dutch Nederlands | formaldehyde … % |
| Polish polski | formaldehyd … % |
| Portuguese português | formaldeído a … % |
| Romanian română | formaldehidă … % |
| Slovak slovenčina | formaldehyd … % |
| Slovenian slovenščina | formaldehid … % |
| Finnish suomi | formaldehydi … % |
| Swedish svenska | formaldehyd ... % |
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
Formaldehyde GHS label elements
Everything CLP Annex VI fixes for Formaldehyde, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Formaldehyde
- May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
- Suspected of causing genetic defects <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
- Fatal if inhaled.
- Harmful if swallowed.
- Causes severe skin burns and eye damage.
- May cause an allergic skin reaction.
- Corrosive to the respiratory tract.
- Obtain special instructions before use.
- Do not breathe dust/fume/gas/mist/vapours/spray.
- Avoid breathing dust/fume/gas/mist/vapours/spray.
- Do not eat, drink or smoke when using this product.
- Use only outdoors or in a well-ventilated area.
- Contaminated work clothing should not be allowed out of the workplace.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF SWALLOWED:
- IF INHALED:
- IF exposed or concerned:
- Immediately call a POISON CENTER/doctor/…
- Call a POISON CENTER/doctor/… if you feel unwell.
- Get medical advice/attention.
- Rinse mouth.
- Do NOT induce vomiting.
- If skin irritation or rash occurs:
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Formaldehyde in the GHS label constructor →
07 · Health hazards
Formaldehyde health hazards and exposure limits
Formaldehyde hazard summary
At room temperature, formaldehyde is a colorless, flammable gas that has a distinct, pungent smell. It is also known as methanal, methylene oxide, oxymethyline, methylaldehyde, and oxomethane. Formaldehyde is naturally produced in small amounts in our bodies. It is used in the production of fertilizer, paper, plywood, and urea-formaldehyde resins. It is also used as a preservative in some foods and in many products used around the house, such as antiseptics, medicines, and cosmetics.
Source: Agency for Toxic Substances and Disease Registry (ATSDR)
Formaldehyde carcinogenicity classification
Cancer Classification: Group B1 Probable Human Carcinogen
Source: Hazardous Substances Data Bank (HSDB)
Formaldehyde: Known 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.
Formaldehyde occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 0.75 [ppm], STEL(OSHA) = 2 ppm | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 0.75 ppm [0.5 ppm Action Level] | Occupational Safety and Health Administration (OSHA) |
| PEL | 2 ppm | Occupational Safety and Health Administration (OSHA) |
| REL | 0.016 ppm | Occupational Safety and Health Administration (OSHA) |
| REL | 0.1 ppm [15 minutes] | Occupational Safety and Health Administration (OSHA) |
| REL | Ca TWA 0.016 ppm C 0.1 ppm [15-minute] See Appendix A | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 20 ppm ; A potential occupational carcinogen. (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 20 ppm ; A potential occupational carcinogen. [From NPG: Formalin (as formaldehyde)] (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 20.0 [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
Formaldehyde 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.
Formaldehyde boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | -19.5 °C (-3.1 °F) | HSDB | |
| 19.1 °C (66.4 °F) | Formaldehyde 37% uninhibited | HSDB | |
| -21.11 °C (-6 °F) | NIOSH |
Formaldehyde melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -92 °C (-133.6 °F) | HSDB | |
| -92.22 °C (-134 °F) | NIOSH |
Formaldehyde density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 0.8 g/cm³ | ICSC | |
| 1.08 g/cm³ | at 25 °C | CAMEO |
Formaldehyde solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | In water, 4.00X10+5 mg/L at 20 °C | at 20 °C | HSDB |
| In water, 95 weight % at 20 °C | at 20 °C | HSDB | |
| In water, miscible at 25 °C | at 25 °C | HSDB |
Formaldehyde vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 1 mmHg | Formalin | HSDB |
| 1 mmHg | CAMEO | ||
| 3890 mmHg | at 25 °C | HSDB |
Formaldehyde flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 85 °C (185 °F) | Gas | HSDB |
| 50 °C (122 °F) | Formaldehyde 37%, 15% methanol | HSDB | |
| 85 °C (185 °F) | HSDB |
Formaldehyde autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 423.89 °C (795 °F) | HSDB | |
| 430 °C (806 °F) | CAMEO |
Formaldehyde lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 7 % by volume | HSDB |
Formaldehyde upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 73 % by volume | HSDB |
Formaldehyde vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 1.067 (air = 1) | HSDB | |
| 1.04 (air = 1) | CAMEO | ||
| 1.08 (air = 1) | ICSC |
Formaldehyde odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | 0.5 to 1.0 ppm | HSDB | |
| Detection: media= water: 4.99x10+1 ppm | Chemically pure | HSDB | |
| Detection: media= water: 2.50x10+1 ppm | Purity not specified | HSDB |
Formaldehyde critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 139.2 °C (282.6 °F) | range, midpoint shown | HSDB |
Formaldehyde corrosivity
| Property | Value | Conditions | Source |
|---|---|---|---|
| Corrosivity | Aqueous formaldehyde is corrosive to carbon steel, but formaldehyde in gas phase is not. | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Formaldehyde 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.
Formaldehyde fire potential
Flammable liquid when exposed to heat or flame; can react vigorously with oxidizers. ... The gas is a more dangerous fire hazard than the vapor.
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Formaldehyde storage and handling
Formaldehyde reactive group
CAMEO Chemicals places Formaldehyde in the reactive groups Aldehydes, Polymerizable Compounds. Compatibility with other chemicals is worked out from the group, not from the individual substance — which is why two substances you have never seen react can still be flagged as a pair that must be separated.
A reactive group is a CAMEO Chemicals (US NOAA) grouping, not a GHS hazard class: it has no code, no category and no legal force. It is what the storage compatibility matrix on this site computes from.
Formaldehyde safe storage
Fireproof. Cool. Separated from incompatible materials. See Chemical Dangers.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Formaldehyde storage conditions
... Minimum storage temperature to prevent polymerization range from 83 °F for 37% formaldehyde containing 0.05% methyl alcohol to 29 °F for formaldehyde containing 15% methyl alcohol.
Source: Hazardous Substances Data Bank (HSDB)
Formaldehyde incompatible materials
(Amines) exothermic reaction, (AZO cmpd) exothermic reaction giving off nitrogen gas, (caustics) heat generation and violent polymerization, (dithiocarbamates) formation of flammable gasses and toxic fumes, formation of carbon disulfide may result, (alkali and alkaline earth metals) heat generation and formation of flammable hydrogen gas, (nitrides) heat generation, formation of flammable ammonia gas and violent polymerization, (nitro compd) heat generation, (unsaturated aliphatics and sulfides) heat generation, (organic peroxides) violent reaction, (oxidizing agents) heat generation, fire, and decomposition, (reducing agents) heat generation and formation of flammable gasses. /From table/
Source: Hazardous Substances Data Bank (HSDB)
Formaldehyde reactivity
FORMALDEHYDE, SOLUTION, reacts violently with strong oxidizing agents (hydrogen peroxide, performic acid, perchloric acid in the presence of aniline, potassium permanganate, nitromethane). Reacts with bases (sodium hydroxide, potassium hydroxide, ammonia), and with nitrogen dioxide (explosive reaction around 180 °C). Reacts with hydrochloric acid to form highly toxic bis(chloromethyl) ether. Polymerization reaction with phenol may develop sudden destructive pressure [Bretherick, 5th ed., 1995, p.168].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Formaldehyde in the storage compatibility matrix →
11 · Transport
Formaldehyde 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.
Formaldehyde under UN 1198 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| FORMALDEHYDE SOLUTION, FLAMMABLE | 3 | FC | III | |
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) |
|---|---|---|---|
| Formaldehyde solutions, flammable | 3 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 3 is “Flammable and combustible liquid” (49 CFR 173.2).
Formaldehyde under UN 2209 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| FORMALDEHYDE SOLUTION with not less than 25 % formaldehyde | 8 | C9 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 8 is “Corrosive substances” (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) |
|---|---|---|---|
| Formaldehyde solutions, with not less than 25 percent formaldehyde | 8 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 8 is “Corrosive material” (49 CFR 173.2).
12 · Questions
Formaldehyde — frequently asked questions
What is the CAS number of Formaldehyde?
The CAS number of Formaldehyde is 50-00-0. Its EC number is 200-001-8.
What is the chemical formula of Formaldehyde?
The molecular formula of Formaldehyde is CH2O and its molecular weight is 30.026 g/mol.
What does a Formaldehyde label have to show?
Under CLP Annex VI the label for Formaldehyde carries the pictograms Health hazard, Skull and crossbones and Corrosion and the signal word is Danger.
Is Formaldehyde flammable?
CLP Annex VI assigns Formaldehyde 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 85 °C (185 °F), Gas (HSDB).
Is Formaldehyde a carcinogen?
Yes. CLP Annex VI classifies Formaldehyde as a category 1A or 1B carcinogen and assigns it H350: may cause cancer. IARC places it in Group 1: carcinogenic to humans.
What is the exposure limit for Formaldehyde?
The US occupational exposure limit reported for Formaldehyde is 0.75 [ppm], STEL(OSHA) = 2 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 Formaldehyde?
The boiling point reported for Formaldehyde is -19.5 °C (-3.1 °F) (HSDB).
What is the melting point of Formaldehyde?
The melting point reported for Formaldehyde is -92 °C (-133.6 °F) (HSDB).
How should Formaldehyde be stored?
... Minimum storage temperature to prevent polymerization range from 83 °F for 37% formaldehyde containing 0.05% methyl alcohol to 29 °F for formaldehyde containing 15% methyl alcohol. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Formaldehyde
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