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Description of key information

Short description of key information on bioaccumulation potential result: 
Potassium and chloride are essential constituents and two of the most abundant ions in all humans, as in all animal species.
Oral uptake, transport, distribution, excretion, and the homeostatic regulation of KCl is well established, as are the mechanisms of action.
KCl is essential for intracellular osmotic pressure and buffering, cell permeability, acid-base balance, muscle contraction and nerve function.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

Within the OECD ICCA HPV program the available data of potassium chloride are already reviewed and

evaluated. The results were published as OECD SIDS by UNEP in 2003:

The following summary of the available data is written in the section toxicokinetics, metabolism, mechanism of action

Potassium and chloride are essential constituents and two of the most abundant ions in all animal

species. In adult humans, the total body potassium is approx. 3.5 mol (135 g). 98 % of this is

located intracellular (150 mmol/l), the extracellular potassium concentration is approx. 4 mmol/l.

Total body chloride in adult humans is approx. 2.1 mol (75 g). 80 % of this is located extracellularly

(120 mmol/l); the intracellular concentration of chloride is approx. 3-4 mmol/l.

The metabolism and mechanisms of action of potassium and chloride are well reviewed in standard

textbooks on pharmacology and physiology.

Metabolism, biotransformation and kinetics:

About 90 % of the ingested dose of potassium is absorbed by passive diffusion in the membrane of

the upper intestine. Potassium is distributed to all tissues where it is the principal intracellular

cation. Insulin, acid-base status, aldosterone, and adrenergic activity regulate cellular uptake of

potassium.

The majority of ingested potassium is excreted in the urine via glomelural filtration. The distal

tubules are able to secrete as well as reabsorb potassium, so they are able to produce a net secretion of

potassium to achieve homeostasis in the face of a potassium load due to abnormally high levels of

ingested potassium. About 15 % of the total amount of potassium excreted is found in faeces. Cl

leaves the tubular lumen by secondary active transport of sodium, and also passive diffusion.

Excretion and retention of potassium is mainly regulated by the main adrenal cortical hormones.

Normal homeostatic mechanisms controlling the serum potassium levels allow a wide range of

dietary intake. The renal excretory mechanism is designed for efficient removal of excess K, rather

for its conservation during deficiency. Even with no intake of K, humans lose a minimum of 585-

1170 mg K per day. However, the distribution of potassium between the intracellular and the

extracellular fluids can markedly affect the serum potassium level without a change in total body

potassium.

Mechanisms of action:

K+ is the principal cation mediating the osmotic balance of the body fluids. In animals, the

maintenance of normal cell volume and pressure depends on Na+ and K+ pumping. The K+/Na+

separation has allowed for evolution of reversible transmembrane electrical potentials essential for

nerve and muscle action in animals, and both potassium and chloride are important in transmission

of nerve impulses to the muscle fibers.

Potassium transport through the hydrofobic interior of a membrane can be facilitated by a number

of natural compounds that form lipid-soluble alkali metal cation complexes. Potassium serves the

critical role as counterion for various carboxylates, phosphates and sulphates, and stabilizes

macromolecular structures.

Potassium and chloride is also important in the regulation of the acid-base balance of the body.

Potassium is the principal base in tissues of blood cells, and Cl maintains electrochemical neutrality

by anion exchange with bicarbonate (the chloride shift) in the CO2 transport in the blood red cells.

Discussion on bioaccumulation potential result:

Within the OECD ICCA HPV program the available data of potassium chloride are already reviewed and

evaluated. The results were published as OECD SIDS by UNEP in 2003 see summary and discussion of toxicokinetics.

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