Naphthenic acids, bismuth salts

Endpoint summary

Description of key information

There is no information available on toxicokinetics of naphthenic acids, bismuth salts and also on bsimuth compounds and naphthenic acids, information on absorption, distribution, metabolism and excretion is very limited.

Bismuth compounds are only absorbed to a negligible extent via the GI tract and even at low gastric pH and in presence of hydrochloric acid they form insoluble or sparingly soluble bismuth oxide, bismuth hydroxide or bismuth oxychloride (BiOCl) so that the absorption of bismuth from the human gastro-intestinal tract (GIT) and systemic exposure to bismuth is poor (< 1% was estimated). This is supported by the absence of any findings in oral toxicity studies, even if water soluble bismuth compounds were dosed. As the naphthenic acids, bismuth salts are insoluble (solubility in water < 0.036 mg/L), absorption of the substance via the GIT is considered low and conservatively assessed as less than 10%. The same applies to dermal and inhalation exposure routes, whereas inhalation exposure for this substance is not considered likely.

Also, information on naphthenic acids with respect to absorption, distribution, metabolism and excretion is limited, but effects seen in oral studies indicate that some absorption occurs and distribution via blood is assumed. However, no toxicokinetic data are available. It is expected, that metabolism is low and most of the naphthenic acids, if not all, are excreted rather rapidly.

Overall, absorption rates for naphthenic acids, bismuth salts are assumed less than 10% for all routes of potential exposure (oral, dermal, inhalative) and considering the ionic structure, excretion is expected being efficient and thus there is low concern for bioaccumulation expected.

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Absorption rate - oral (%):

10

Absorption rate - dermal (%):

10

Absorption rate - inhalation (%):

10