What is Caesium?

Caesium, or cesium (chemical formula: Cs), is a silvery-white, soft metal. It has a relatively low melting point and turns to liquid at temperatures slightly higher than room temperature. Caesium is extremely reactive with air and water—oxidises in air and spontaneously igniting in air containing moisture. Caesium is normally immersed under mineral oil.

What is Caesium used for?

Caesium has several uses, they include:

  • Atomic clocks: the most accurate timekeeping devices in the world. 
  • Radiation: Caesium-137 is used in medical radiation therapy devices. 
  • Petroleum exploration: used in geophysical surveys to identify potential oil and gas deposits. 
  • Catalysts: used as a catalyst in some chemical reactions, particularly in the production of organic compounds.
  • Ion engines: used in ion engines for spacecraft propulsion.
  • Spectroscopy: used in spectroscopy to study the properties of atoms and molecules.
Atomic clocks rely on the use of caesium for their accuracy.
Atomic clocks rely on the use of caesium for their accuracy.

Caesium Hazards

The routes of exposure for caesium include inhalation, ingestion and skin and eye contact.

Inhalation of caesium mists and dusts can be damaging to those with already impaired respiratory function, or circulatory or nervous system damage. Symptoms of inhalataion can include sudden thirst, a sweet/metallic/foul taste, throat irritation, diarrhoea, excessive urination, sweating, restlessness and extreme exhaustion

Ingestion of caesium can cause chemical burns in the mouth and gastrointestinal tract. 

Caesium can cause chemical burns when in direct contact with the skin and entry into the bloodstream through open cuts or wounds may also lead to other harmful effects.

Direct eye contact with the chemical can lead to chemical burns that can cause severe eye damage. Caesium in metal dusty form can cause abrasion to the eye and even penetrate the eye. 

Repeated exposure to caesium can lead to erosion of the teeth, inflammation and ulcers in the mouth, bronchial irritation.

Caesium Safety

If inhaled, remove the individual from the contaminated area to the nearest fresh air source and ensure they are kept warm and rested. If the patient is not breathing and you are qualified to do so, administer CPR, preferably with a bag-valve mask device. Monitor the patient’s breathing and pulse continuously. Seek medical attention immediately.

If swallowed, urgent hospital treatment is likely to be needed. Do not induce vomiting, however if vomiting occurs, lean the patient forward of placed on their left side to prevent aspiration. Give the patient water to rinse out their mouth and they should slowly drink as much as they comfortably can. Seek medical attention immediately. 

In the event of exposure to skin, remove all contaminated clothing, footwear and accessories and flush the affected area with plenty of water, using a safety shower if available. Seek medical attention immediately.

If eye exposure occurs, flush the eye with plenty of cool water for at least 15 minutes, ensuring to flush behind the eyelids. Removing contact lenses should only be performed by a skilled professional. Seek medical attention immediately. 

Caesium Safety Handling

Emergency eyewash fountains and safety showers should be accessible in the event of exposure to the chemical. Adequate ventilation to remove or dilute any air contaminants is required and it must be designed to handle explosive dusts.

The PPE recommended when handling caesium includes chemical goggles, full face shields (in addition to goggles), PVC/leather gloves, overalls, safety footwear/gumboots and static-free clothing. 

Being highly explosive in certain conditions, ensure caesium is handled with the respect and care necessary. Click here for a trial of our SDS Management Software or contact us at for more information about our chemicals management solutions.