Trilead dioxide phosphonate

Oxidising properties

Description of key information

Read-across from lead tetroxide:

The read-across approach used falls under RAAF Scenario 2: analogue approach for which the hypothesis is based on different compounds with the same type of effect.

The absence of effects obtained in a study conducted with the source substance, lead tetroxide, is used to predict the same absence of effects that would be observed in a study with the target substance if it were to be conducted.

Key value for chemical safety assessment

Oxidising properties:

non oxidising

Additional information

On the basis of read-across from lead tetroxide, together with long-term industrial handling experience, testing of trilead dioxide phosphonate is not required, in accordance with Regulation (EC) No 1907/2006, Annex XI, Section 1.5: read-across of results and conclusion on classification for lead tetroxide to trilead dioxide phosphonate is justifiable, under RAAF scenario 2.

Justification for classification or non-classification

Trilead dioxide phosphonate does not require classification for oxidising properties based on a comparison of the oxidation states of the target substance and the source substance (orange lead), upon which testing has concluded the substance is "not oxidising".

A test according to EU Method A.17 was carried out on lead tetroxide (orange lead; Pb3O4) in 2005. From the test results it was concluded that orange lead does not exhibit oxidising properties.

In the sense of classification for supply and transport an oxidising solid is a solid which, while in itself not necessarily combustible, may - generally by yielding oxygen - cause or contribute to the combustion of other material. From a chemical perspective, they are substances which usually react by removing electrons from other substances. An oxidising agent is therefore normally found in one of its higher possible oxidation states because it will gain electrons and thus itself be reduced.

In the test substance, the lead is present in two oxidation states +II and +IV. However, the lead in trilead dioxide phosphonate is only in the oxidation state +II and is thus intrinsically less oxidising. The substance also contains phosphorous in the form of an H-phosphonate ion, in which the oxidation state of the phosphorous is +III and not the higher +V state. Bonding beteween the phosphorous and the oxygen is strong and stable and thus the ion is not prone to yielding oxygen.

Therefore it is scientifically implausible that trilead dioxide phosphonate would exhibit oxidising properties sufficient for classification, considering the comparable compound Pb3O4 does not and is not classified as an oxidising solid on the basis of A.17 testing.

Furthermore, no oxidising properties have been observed throughout long-term industrial handling of the substance, and it is not classified for oxidising properties according to UN Transport regulations.

On the basis of read-across from lead tetroxide, together with long-term industrial handling experience, testing of pentalead tetraoxide sulphate is not required, in accordance with Regulation (EC) No 1907/2006, Annex VII, Section 7.13, Column 2 and Annex XI, Section 1.5: read-across of results and conclusion on classification for lead tetroxide to trilead dioxide phosphonate is justifiable, under RAAF scenario 2.