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Record Information
Creation Date2009-03-06 18:58:18 UTC
Update Date2014-12-24 20:21:21 UTC
Accession NumberT3D0217
Common NamePotassium-40
ClassSmall Molecule
DescriptionPotassium-40 is a naturally occurring radioactive isotope of potassium. Potassium is the chemical element with the symbol K and atomic number 19. Potassium is widely distributed in nature and is present in all plant and animal tissues. Potassium-40 comprises about 0.012% of naturally occurring potassium. It is the predominant radioactive component in human tissues and in most food. Potassium-40 has a half-life of 1.3 billion years and emits beta and gamma radiation. (1, 3)
Compound Type
  • Food Toxin
  • Inorganic Compound
  • Metal
  • Natural Compound
  • Pollutant
  • Radioactive
  • Radioactive Isotope
Chemical Structure
Potassium 40
Potassium, isotope of mass 40
Chemical FormulaK
Average Molecular Mass39.964 g/mol
Monoisotopic Mass39.964 g/mol
CAS Registry Number13966-00-2
IUPAC Name(⁴⁰K)potassium
Traditional Name(⁴⁰K)potassium
InChI IdentifierInChI=1S/K/i1+1
Chemical Taxonomy
ClassificationNot classified
Biological Properties
StatusDetected and Not Quantified
Cellular Locations
  • Cytoplasm
  • Extracellular
Biofluid LocationsNot Available
Tissue LocationsNot Available
PathwaysNot Available
ApplicationsNot Available
Biological RolesNot Available
Chemical RolesNot Available
Physical Properties
AppearanceSilvery-white metal.
Experimental Properties
Melting PointNot Available
Boiling PointNot Available
SolubilityNot Available
LogPNot Available
Predicted Properties
Physiological Charge0ChemAxon
Hydrogen Acceptor Count0ChemAxon
Hydrogen Donor Count0ChemAxon
Polar Surface Area0 ŲChemAxon
Rotatable Bond Count0ChemAxon
Refractivity0 m³·mol⁻¹ChemAxon
Polarizability1.78 ųChemAxon
Number of Rings0ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
SpectraNot Available
Toxicity Profile
Route of ExposureOral (1) ; inhalation (1)
Mechanism of ToxicityThe ionizing radiation produced by potassium causes cellular damage that includes DNA breakage, accurate or inaccurate repair, apoptosis, gene mutations, chromosomal change, and genetic instability. This leads to loss of normal cell and tissue homeostasis, and development of malignancy. Ionizing radiation that does not directly damage DNA can produce reactive oxygen intermediates that directly affect the stability of p53, an important enzyme in cell-cycle regulation, and produce oxidative damage to individual bases in DNA and point mutations by mispairing during DNA replication. (2)
MetabolismPotassium-40 behaves in the body in the same manner as other potassium isotopes. Potassium is almost completely absorbed upon ingestion, moving quickly from the gastrointestinal tract to the bloodstream. The potassium-40 that enters the bloodstream after ingestion or inhalation is quickly distributed to all organs and tissues. Potassium-40 is eliminated from the body with a biological half-life of 30 days. The potassium content of the body is under strict homeostatic control (in which the amount retained is actively regulated by the body to achieve the normal range required for system functions), and it is not influenced by variations in environmental levels. Hence, the potassium-40 content in the body is constant, with an adult male having about 0.1 microcurie or 100,000 pCi. Each year this isotope delivers doses of about 18 millirem (mrem) to soft tissues of the body and 14 mrem to bone. Potassium cations are important in neuron function, influencing osmotic balance between cells and the interstitial fluid, allowing muscle contraction and the sending of all nerve impulses through action potentials, and maintaining fluid and electrolyte balance in the body. (1, 3)
Toxicity ValuesNot Available
Lethal DoseNot Available
Carcinogenicity (IARC Classification)Internalized radionuclides that emit β particles are carcinogenic to humans (Group 1) (5). Potassium-40 undergoes beta decay.
Uses/SourcesThere are no specific commercial or medical uses associated with the radioactive properties of potassium-40. (1)
Minimum Risk LevelNot Available
Health EffectsPotassium-40 presents external as well as internal health hazard. The strong gamma radiation makes external exposure to this isotope a concern. While in the body, potassium-40 poses a health hazard from both the beta particles and gamma rays. The health hazard of potassium-40 is associated with cell damage caused by the ionizing radiation that results from radioactive decay, with the general potential for subsequent cancer induction. (1)
SymptomsExposure to high doses of ionizing radiation results in acute radiation syndrome, which can cause skin burns, hair loss, nausea, vomiting, dizziness, disorientation, low blood pressure, headache, fatigue, weakness, fever, birth defects, illness, infection, and death. (2, 4)
TreatmentTreatment reversing the effects of irradiation is currently not possible. Anaesthetics and antiemetics are administered to counter the symptoms of exposure, as well as antibiotics for countering secondary infections due to the resulting immune system deficiency. (4)
Normal Concentrations
Not Available
Abnormal Concentrations
Not Available
DrugBank IDNot Available
HMDB IDNot Available
PubChem Compound ID6328542
ChEMBL IDNot Available
ChemSpider ID4886606
KEGG IDNot Available
UniProt IDNot Available
ChEBI IDNot Available
BioCyc IDNot Available
CTD IDNot Available
Stitch IDPotassium-40
PDB IDNot Available
ACToR IDNot Available
Wikipedia LinkNot Available
Synthesis ReferenceNot Available
MSDSNot Available
General References
  1. Argonne National Laboratory, EVS (2005). Human Health Fact Sheet, Potassium-40. [Link]
  2. ATSDR - Agency for Toxic Substances and Disease Registry (1999). Toxicological profile for ionizing radiation. U.S. Public Health Service in collaboration with U.S. Environmental Protection Agency (EPA). [Link]
  3. Wikipedia. Potassium. Last Updated 23 August 2009. [Link]
  4. Wikipedia. Radiation poisoning. Last Updated 22 August 2009. [Link]
  5. International Agency for Research on Cancer. 2012. Radiation: A Review of Human Carcinogens. IARC monograph, volume 100D. [Link]
Gene Regulation
Up-Regulated GenesNot Available
Down-Regulated GenesNot Available


1. DNA
General Function:
Used for biological information storage.
Specific Function:
DNA contains the instructions needed for an organism to develop, survive and reproduce.
Molecular Weight:
2.15 x 1012 Da
  1. ATSDR - Agency for Toxic Substances and Disease Registry (1999). Toxicological profile for ionizing radiation. U.S. Public Health Service in collaboration with U.S. Environmental Protection Agency (EPA). [Link]