Substance profile
Arsenic
Arsenic is it exists in three allotropic forms, the yellow (alpha), black (beta) and grey (gamma) forms and is odorless.
01 · Identification
What Arsenic is
Arsenic is it exists in three allotropic forms, the yellow (alpha), black (beta) and grey (gamma) forms and is odorless. Its molecular formula is As and its molecular weight is 74.922 g/mol. It boils at 613 °C, melts at 613 °C, is practically insoluble in water.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
Arsenic identifiers and molecular data
Arsenic CAS number and EC number
Arsenic molecular formula and molecular weight
03 · GHS classification
Arsenic hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Arsenic pictograms and signal word
Arsenic hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - oral GHS chapter 3.1 | Category 3 | H301 | GHS06 |
| Acute toxicity - inhalation GHS chapter 3.1 | Category 3 | H331 | GHS06 |
| 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 |
Arsenic hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H331 | Toxic if inhaled. |
| H301 | Toxic 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 Arsenic. 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 Arsenic
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 Arsenic 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
Arsenic precautionary statements
CLP Annex VI assigns 10 precautionary statements to Arsenic. 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
Arsenic 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 | арсен |
| Spanish español | Arsénico |
| Czech čeština | arsen |
| Danish dansk | arsen |
| German Deutsch | Arsen |
| Estonian eesti | arseen |
| Greek ελληνικά | αρσενικό |
| English English | arsenic |
| French français | arsenic |
| Croatian hrvatski | arsen |
| Italian italiano | arsenico |
| Latvian latviešu | arsēns |
| Lithuanian lietuvių | arsenas |
| Hungarian magyar | arzén |
| Maltese Malti | arseniku |
| Dutch Nederlands | arseen |
| Polish polski | arsen |
| Portuguese português | arsénio |
| Romanian română | arsen |
| Slovak slovenčina | arzén |
| Slovenian slovenščina | arzen |
| Finnish suomi | arseeni |
| Swedish svenska | arsenik |
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
Arsenic GHS label elements
Everything CLP Annex VI fixes for Arsenic, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Arsenic
- Toxic if inhaled.
- Toxic if swallowed.
- Very toxic to aquatic life.
- Very toxic to aquatic life with long lasting effects.
- Do not breathe 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.
- Avoid release to the environment.
- IF SWALLOWED:
- IF INHALED:
- Immediately call a POISON CENTER/doctor/…
- 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 Arsenic in the GHS label constructor →
07 · Health hazards
Arsenic health hazards and exposure limits
Arsenic hazard summary
Arsenic is a naturally occurring element widely distributed in the earth's crust. In the environment, arsenic is combined with oxygen, chlorine, and sulfur to form inorganic arsenic compounds. Arsenic in animals and plants combines with carbon and hydrogen to form organic arsenic compounds. Inorganic arsenic compounds are mainly used to preserve wood. Copper chromated arsenic (CCA) is used to make "pressure-treated" lumber. CCA is no longer used in the U.S. for residential uses; it is still used in industrial applications. Organic arsenic compounds are used as pesticides, primarily on cotton plants.
Source: Agency for Toxic Substances and Disease Registry (ATSDR)
Arsenic carcinogenicity classification
CLASSIFICATION: A; human carcinogen. BASIS FOR CLASSIFICATION: Based on sufficient evidence from human data. An increased lung cancer mortality was observed in multiple human populations exposed primarily through inhalation. Also, increased mortality from multiple internal organ cancers (liver, kidney, lung, and bladder) and an increased incidence of skin cancer were observed in populations consuming drinking water high in inorganic arsenic. HUMAN CARCINOGENICITY DATA: Sufficient. ANIMAL CARCINOGENICITY DATA: Inadequate. /based on former classification system/
Source: Hazardous Substances Data Bank (HSDB)
Evaluation: There is sufficient evidence in humans that arsenic in drinking-water causes cancers of the urinary bladder, lung and skin ... Overall evaluation: Arsenic in drinking-water is carcinogenic to humans (Group 1). /Arsenic in drinking-water/
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.
Arsenic occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 0.01 [mg/m3], as As (inorganic compds except arsine), 0.5 mg/m3, as As(organic compds) | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 10 µg/m³ [5 µg/m³ Action Level] | Occupational Safety and Health Administration (OSHA) |
| PEL | 0.5 mg/m³ | Occupational Safety and Health Administration (OSHA) |
| REL | 0.002 mg/m³ [15 minutes] | Occupational Safety and Health Administration (OSHA) |
| REL | Ca C 0.002 mg/m3 [15-minute] See Appendix A | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 5 mg As/m3 ; A potential occupational carcinogen. (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 5.0 [mg/m3], as As (metal, inorganic compds except arsine) | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | 5 mg/cu m (as AS); NIOSH considers arsenic (inorganic cmpd, as As) to be a potential occupational carcinogen. /Arsenic (inorganic cmpd, as As)/ | Hazardous Substances Data Bank (HSDB) |
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
Arsenic 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.
Arsenic boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 612.78 °C (1135 °F) | sublimes, at 760 mmHg | CAMEO |
| 612.78 °C (1135 °F) | sublimes | OSHA | |
| Sublimes | sublimes | NIOSH |
Arsenic melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 612.78 °C (1135 °F) | sublimes | NIOSH |
Arsenic density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 5.73 g/cm³ | metal | NIOSH |
| 5.778 g/cm³ | at 25 °C | HSDB | |
| 5.727 g/cm³ | at 25 °C | CAMEO |
Arsenic solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Insol in caustic and nonoxidizing acids | HSDB | |
| Insoluble in water | HSDB | ||
| Insoluble | NIOSH |
Arsenic vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 0 mmHg | approx | NIOSH |
Arsenic autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 180 °C (356 °F) | ICSC |
Arsenic lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | SLIGHTLY EXPLOSIVE IN THE FORM OF DUST WHEN EXPOSED TO FLAME. | HSDB | |
| Metal: Noncombustible Solid in bulk form, but a slight explosion hazard in the form of dust when exposed to flame. | NIOSH |
Arsenic critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 1400 °C (2551.7 °F) | HSDB | |
| Critical pressure: 22.3 MPa | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Arsenic 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.
Arsenic fire potential
CAN BE HEATED TO BURN IN AIR WITH BLUISH FLAME, GIVING OFF AN ODOR OF GARLIC AND DENSE WHITE FUMES OF ARSENIC TRIOXIDE (AS2O3).
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Arsenic storage and handling
Arsenic safe storage
Separated from strong oxidants, acids, halogens and food and feedstuffs. Well closed. Provision to contain effluent from fire extinguishing. Store in an area without drain or sewer access.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Arsenic incompatible materials
Arsine is formed when any inorganic arsenic bearing material is brought in contact with zinc and sulfuric acid.
Source: Hazardous Substances Data Bank (HSDB)
Arsenic reactivity
ARSENIC reacts incandescently with bromine trifluoride, even at 10 °C [Mellor 2:113 1946-47]. Causes bromoazide to explode upon contact. Ignites if ground up together with solid potassium permanganate [Mellor 12:322 1946-47]. Is oxidized by sodium peroxide with incandescence [Mellor 2:490-93 1946-47]. A combination of finely divided arsenic with finely divided bromates (also chlorates and iodates) of barium, calcium, magnesium, potassium, sodium, or zinc can explode by heat, percussion, and friction [Mellor 2:310 1946-47]. Bromine pentafluoride reacts readily in the cold with arsenic. Ignition usually occurs. Reacts vigorously with fluorine at ordinary temperatures [Mellor 9:34 1946-47].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Arsenic in the storage compatibility matrix →
11 · Transport
Arsenic 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.
Arsenic under UN 1558 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| ARSENIC | 6.1 | T5 | II | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 6.1 is “Toxic 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) |
|---|---|---|---|
| Arsenic | 6.1 | II | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 6.1 is “Poisonous materials” (49 CFR 173.2).
12 · Questions
Arsenic — frequently asked questions
What is the CAS number of Arsenic?
The CAS number of Arsenic is 7440-38-2. Its EC number is 231-148-6.
What is the chemical formula of Arsenic?
The molecular formula of Arsenic is As and its molecular weight is 74.922 g/mol.
What does a Arsenic label have to show?
Under CLP Annex VI the label for Arsenic carries the pictograms Skull and crossbones and Environment and the signal word is Danger.
Is Arsenic flammable?
CLP Annex VI assigns Arsenic 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.
Is Arsenic a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Arsenic. Annex VI is a list of agreed classifications, not a list of substances found safe, so this is an absence of a classification rather than a clean bill of health. IARC places it in Group 1: carcinogenic to humans.
What is the exposure limit for Arsenic?
The US occupational exposure limit reported for Arsenic is 0.01 [mg/m3], as As (inorganic compds except arsine), 0.5 mg/m3, as As(organic compds) (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 Arsenic?
The boiling point reported for Arsenic is 612.78 °C (1135 °F), sublimes, at 760 mmHg (CAMEO).
What is the melting point of Arsenic?
The melting point reported for Arsenic is 612.78 °C (1135 °F), sublimes (NIOSH).
Nearby
Substances next to Arsenic
Keep going: substances starting with A, or search the whole database by name, CAS number, pictogram or signal word.