Substance profile
Thallium
Thallium is a bluish-white, very soft, inelastic, easily fusible, heavy metal.
01 · Identification
What Thallium is
Thallium is a bluish-white, very soft, inelastic, easily fusible, heavy metal. It boils at 1473 °C, melts at 304 °C, is practically insoluble in water.
Under the GHS it carries the signal word Danger. It is classed as flammable agents - 3rd degree.
02 · Identifiers
Thallium identifiers and molecular data
Thallium CAS number and EC number
Thallium molecular formula and molecular weight
03 · GHS classification
Thallium hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Thallium pictograms and signal word
Thallium hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - oral GHS chapter 3.1 | Category 1 or 2 | H300 | GHS06 |
| Acute toxicity - inhalation GHS chapter 3.1 | Category 1 or 2 | H330 | GHS06 |
| Specific target organ toxicity - repeated exposure GHS chapter 3.9 | Category 2 | H373 | GHS08 |
| Hazardous to the aquatic environment - chronic GHS chapter 4.1 | Category 4 | H413 | — |
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.
Thallium hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H330 | Fatal if inhaled. |
| H300 | Fatal if swallowed. |
| H373 | May cause damage to organs <or state all organs affected, if known> through prolonged or repeated exposure <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>. |
| H413 | May cause long lasting harmful effects to aquatic life. |
This page lists only the codes assigned to Thallium. 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 Thallium
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 Thallium 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
Thallium precautionary statements
CLP Annex VI assigns 10 precautionary statements to Thallium. 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
Thallium 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 | талий |
| Spanish español | Talio |
| Czech čeština | thallium |
| Danish dansk | thallium |
| German Deutsch | Thallium |
| Estonian eesti | tallium |
| Greek ελληνικά | θάλλιο |
| English English | thallium |
| French français | thallium |
| Croatian hrvatski | talij |
| Italian italiano | tallio |
| Latvian latviešu | tallijs |
| Lithuanian lietuvių | talis |
| Hungarian magyar | tallium |
| Maltese Malti | tallju |
| Dutch Nederlands | thallium |
| Polish polski | tal |
| Portuguese português | tálio |
| Romanian română | taliu |
| Slovak slovenčina | tálium |
| Slovenian slovenščina | talij |
| Finnish suomi | tallium |
| Swedish svenska | tallium |
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
Thallium GHS label elements
Everything CLP Annex VI fixes for Thallium, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Thallium
- Fatal if inhaled.
- Fatal if swallowed.
- May cause damage to organs <or state all organs affected, if known> through prolonged or repeated exposure <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
- May cause long lasting harmful effects to aquatic life.
- 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/…
- Get medical advice/attention if you feel unwell.
- Rinse mouth.
- Dispose of contents/container to …
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Thallium in the GHS label constructor →
07 · Health hazards
Thallium health hazards and exposure limits
Thallium hazard summary
Pure thallium is a bluish-white metal that is found in trace amounts in the earth's crust. In the past, thallium was obtained as a by-product from smelting other metals; however, it has not been produced in the United States since 1984. Currently, all the thallium is obtained from imports and from thallium reserves.. In its pure form, thallium is odorless and tasteless. It can also be found combined with other substances such as bromine, chlorine, fluorine, and iodine. When it's combined, it appears colorless-to-white or yellow.. Thallium is used mostly in manufacturing electronic devices, switches, and closures, primarily for the semiconductor industry. It also has limited use in the manufacture of special glass and for certain medical procedures.
Source: Agency for Toxic Substances and Disease Registry (ATSDR)
Thallium occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 0.1 [mg/m3], as Tl (Tl and soluble cmpnds) | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 0.1 mg/m³ | Occupational Safety and Health Administration (OSHA) |
| REL | 0.1 mg/m³ | Occupational Safety and Health Administration (OSHA) |
| IDLH | 15 mg Tl/m3 (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 15.0 [mg/m3], as Tl (soluble cmpnds) | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | 15 mg/m³ | Occupational Safety and Health Administration (OSHA) |
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
Thallium 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.
Thallium boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 1473 °C (2683.4 °F) | HSDB | |
| 1457 °C (2654.6 °F) | ICSC | ||
| 1473 °C (2683.4 °F) | at 760 mmHg | DOE PAC |
Thallium melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 304 °C (579.2 °F) | HSDB | |
| 150 °C (302 °F) | OSHA |
Thallium density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 11.8 g/cm³ | HSDB | |
| 11.9 g/cm³ | ICSC | ||
| 1.1 g/cm³ | OSHA |
Thallium solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Insoluble in water; reacts with acid | HSDB | |
| Dissolves in warm dilute mineral acids, forming thallous (+1) salts and liberating hydrogen gas | HSDB |
Thallium vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 1.193e-7 mmHg | HSDB | |
| 0.0075 mmHg | at 609 °C | HSDB | |
| depends upon the specific compound | OSHA |
Thallium flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 215.56 °C (420 °F) | OSHA |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Handling and storage
Thallium storage and handling
Thallium safe storage
Separated from strong acids, fluorine, other halogens and food and feedstuffs. Store only in original container. Well closed.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Thallium storage conditions
Store separated from strong acids, fluorine, other halogens food and feedstuffs
Source: Hazardous Substances Data Bank (HSDB)
Thallium incompatible materials
FLUORINE ACTS SO VIGOROUSLY ON THALLIUM THAT THE METAL BECOMES INCANDESCENT.
Source: Hazardous Substances Data Bank (HSDB)
Thallium reactivity
THALLIUM is a reducing agent. Reacts so vigorously with fluorine that the metal becomes incandescent [Mellor 5:421 1946-47].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Thallium in the storage compatibility matrix →
10 · Questions
Thallium — frequently asked questions
What is the CAS number of Thallium?
The CAS number of Thallium is 7440-28-0. Its EC number is 231-138-1.
What does a Thallium label have to show?
Under CLP Annex VI the label for Thallium carries the pictograms Skull and crossbones and Health hazard and the signal word is Danger.
Is Thallium flammable?
CLP Annex VI assigns Thallium 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 215.56 °C (420 °F) (OSHA).
Is Thallium a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Thallium. 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.
What is the exposure limit for Thallium?
The US occupational exposure limit reported for Thallium is 0.1 [mg/m3], as Tl (Tl and soluble cmpnds) (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 Thallium?
The boiling point reported for Thallium is 1473 °C (2683.4 °F) (HSDB).
What is the melting point of Thallium?
The melting point reported for Thallium is 304 °C (579.2 °F) (HSDB).
How should Thallium be stored?
Store separated from strong acids, fluorine, other halogens food and feedstuffs (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Thallium
Keep going: substances starting with T, or search the whole database by name, CAS number, pictogram or signal word.