Registration Dossier

Administrative data

Link to relevant study record(s)

Description of key information

An experiment to assess the dissolution and bioaccessibility of the test item bismuth silicate was conducted in five physiological media: phosphate-buffered saline (PBS) (pH 7.2), artificial interstitial fluid or Gamble’s solution (pH 7.4), artificial sweat solution (pH 6.5), artificial lysosomal fluid (pH 4.5) and artificial gastric fluid (pH 1.5), selected to simulate relevant human-chemical interactions. The dissolved amount of the test item was quantified by the mass concentration of bismuth. Based on the release of bismuth in five artificial physiological test media, bismuth silicate is considered essentially insoluble in artificial interstitial fluid, sweat solution and PBS, and slightly soluble in gastric fluid (1.00 % bismuth released after 24 hours). Bismuth silicate is more soluble in artificial lysosomal fluid (51.71% of bismuth was released after 72 hours).

Key value for chemical safety assessment

Absorption rate - oral (%):
50
Absorption rate - dermal (%):
50
Absorption rate - inhalation (%):
100

Additional information

In the absence of specific studies on either the target or source substances relating to absorption via the various exposure routes, or toxicokinetic data from in vivo toxicity studies, the default values for absorption via oral, dermal or inhalation have been entered. The dissolution data generally supports the selection of these values since dissolution into lysosomal fluid was significantly greater than any of the other artificial fluids whilst dissolution into gastric, sweat and interstitial fluids were much lower and very similar.