Aluminium nitrate

Endpoint summary

Description of key information

The toxicokinetics of the aluminium ion component of the substance aluminium nitrate are elucidated using data from a number of publlished reviews and original research.  

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

0.3

Absorption rate - dermal (%):

0.3

Absorption rate - inhalation (%):

1.5

Additional information

A comprehensive review of the toxicokinetics of aluminium (ATSDR, 2008) concludes that aluminium is poorly absorbed following either oral or inhalation exposure and is essentially not absorbed dermally. Approximately 0.1-0.6% of ingested aluminium is usually absorbed, although the gastrointestinal absorption of some forms of aluminium may be lower. Unabsorbed aluminium is excreted in the faeces. The bioavailability of aluminium is strongly influenced by the aluminium compound and also by the presence of dietary constituents which can complex with aluminium and thereby enhance or inhibit its absorption. The main mechanism of absorption is passive diffusion through paracellular pathways. Aluminium binds to various ligands in the blood and distributes to every organ, with highest concentrations found in bone and lung tissues. Absorbed aluminium is excreted principally in the urine and, to a lesser extent, in the bile.

In a recent review, EFSA (2011) conclude that the oral bioavailability of aluminium is variable and is influenced by a number of factors including the nature of the aluminium salt and the presence of other chemicals in the gastrointestinal tract. It was concluded that the available studies indicate that the oral bioavailability of aluminium in humans and experimental animals from drinking water is approximately 0.3%, whereas the bioavailability of aluminium from food and beverages generally is considered to be lower, about 0.1%. In a further published review (Yokel & McNamara, 2001), the authors conclude that the oral bioavailability of aluminium from water is approximately 0.3%. The inhalation bioavailability of soluble aluminium appears to be approximately 1.5% in the industrial environment.

In a study in the rabbit (Yokel & McNamara, 1988), the oral absorption of aluminium from aluminium nitrate was found to be relatively high compared to other forms of aluminium (with the exception of aluminium citrate). However a study in the rat using perfused sections of small intestine (Cunat et al, 2000) reports the lowest bioavailability of aluminium from Aluminium nitrate compared to other forms of aluminium investigated.

For the purposes of the risk assessment, an oral absorption value of 0.3% is used (EFSA, 2011) based on data for Al in drinking water and relevant to studies using gavage administration. An inhalation absorption value of 1.5% is used (Yokel & McNamara, 2001).