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Description of key information

A toxicokinetics assessment was conducted for bismuth subnitrate using available data including data from the published literature. Based on the results of this assessment, the substance is considered to have low bioaccumulation potential.

Key value for chemical safety assessment

Bioaccumulation potential:
low bioaccumulation potential
Absorption rate - oral (%):
0.5
Absorption rate - dermal (%):
0.1
Absorption rate - inhalation (%):
12.9

Additional information

A toxicokinetics assessment was conducted for bismuth subnitrate using available data including data from the published literature.

Absorption: The bismuth portion of pharmaceutical preparations of bismuth subnitrate is poorly absorbed from the gastrointestinal tract with an oral bioavailability reported to be < 0.01%. There are very few data on dermal absorption of bismuth, however, absorption via this route is expected to be low. In humans, ingested nitrate is rapidly absorbed from the proximal small bowel (oral bioavailability is at least 92%). Based on particle size distribution data and modelling of deposition in the respiratory tract, it is estimated that between 1.0% and 12.9% of bismuth subnitrate may be absorbed via inhalation.

Distribution: The small amount of bismuth that is absorbed is distributed to various organs with the highest concentration expected to be in the kidney. The results of a study in guinea pigs with radiobismuth suggest poor placental transfer of bismuth (< 1%), however, bismuth can cross the blood-brain barrier. The distribution half-life of bismuth is 1 to 4 hours and the plasma half-life is 5 to 11 days. Nitrate is distributed throughout the body; it does not accumulate in the body.Hydroxide ions are normal constituents of the body fluids and therefore are likely to be widely distributed in the body.

 Elimination: Excretion of absorbed bismuth is via the urinary and faecal routes and the urinary excretion half-life lasts between 21 to 72 days. Unabsorbed bismuth is excreted in the faeces. Nitrates are rapidly converted in the liver to denitrated metabolites and inorganic nitrites, which are then excreted in urine. Approximately 60% to 70% of an ingested nitrate dose is excreted in urine within the first 24 hours.