Dichlorodioctylstannane

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

There are two relevant studies available to cover the present endpoint, and an additional study which should however be disregarded

First, a pre-GLP study conducted similar to the method formerly recommended by US FDA and described by Draize on the registered substance, dichlorodioctylstannane, itself. There were some deficiencies in documentation identified, and some methodological shortcomings compared to recent guidelines. However, it was conducted in a scientifically reasonable manner, and no animal showed any sensitizing reaction. As the CLP guidance strongly discourages the use of non-standard guinea pig sensitisation tests for classification and labelling purposes, the second study on the read-across substance dioctyltin oxide was taken into consideration. It was conducted according toOECD 429 & EU Method B.42 under GLP, no deficiencies, except the fact that a read-across substance was used, were identified, and it revealed a consistently negative result. This studyis as such suitable to be used for classification according to the CLP regulation.Dioctyltin oxide is suitable for read-across to the registered substance as they share the identical octyltin basis structure which is the only relevant structure here for the induction of possible toxicological effects. Neither the oxygen not the chlorine here is expected to have any effects on the non-sensitizing properties of the basis structure, e.g. no relevant interaction with the bodies‘ proteins can be expected.

The third available study was formerly used in the dossier of DOTC as the old doctrine was that all Dioctyltin compounds hydrolyse into the dichloride. It was shown in different studies, that DOTE does not hydrolyse into the dichloride, it hydrolyses into the “Mono ETHG chloride” under release of the 2-Ethylhexyl mercaptoacetate ligand. So it is considered, that the ligand is responsible for the sensitizing properties of DOTE. This fact is in accordance with the “Begründung zu n-Octylzinnverbindungen in TRGS 900“ (Rationale for n-octyltin compounds in TGRS 900) of April 2014 of the „Ausschuss für Gefahrstoffe - AGS-Geschäftsführung – BAuA“ (Committee on Hazardous Substances) by the German Federal Institute for Occupational Safety and Health (BAuA): “The observed skin-sensitising effect of DOT(2-EHMA)₂and MOT(2-EHMA)₃is attributable to the cleavable organic ligand and not to the organotin compound”.

Hence, the positive result in the DOTE study does not scientifically reasonably need to be regarded when assessing the skin sensitising properties of DOTC.

Consistently, as the DOTE study can be disregarded and both relevant studies share similar grades of deficiency, a WoE approach was chosen here to clearly demonstrate the non-sensitizing effects of the registered substance.

There is no indication given that the results derived from two animal species are not relevant for human risk assessment, no data gaps were identified and hence, the available information is sufficient to cover the present endpoint.

Migrated from Short description of key information:
Skin sensitization: Draize method (10 intradermal induction injections), albino guinea pig, FDA guideline prior GLP, dichlorodioctylstannane: not sensitising
Skin sensitization: Local lymph node assay, CBA mouse, female, OECD 429 & EU Method B.42, GLP, di-n-octyltin oxide: not sensitising
Skin sensitization (disregarded study): Guinea pig maximisation test, Pilbright white strain (TiF:DHP) guinea pig, m/f, OECD 406, GLP, 2-ethylhexyl 10-ethyl-4,4-dioctyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate: sensitising

Justification for selection of skin sensitisation endpoint:
Only available study on the registered substance itself, which consistently revealed similarly negative results as the other available and reliable study in the WoE approach.

Justification for classification or non-classification

According to Regulation EC No 1272/2008 and Directive 67/548/EEC the substance does not need to be classified as a dermal sensitizer. The study similar to the method described by Draize on the registered substance itself did not show any signs of sensitization. The OECD 429 on the acceptable read-across substance dioctyltin oxide, which is as such suitable for classification according to the CLP regulation, did not reveal a more than 3-fold increase in radiation. Hence, the substance does not need to be classified as dermal sensitizer, and so neither does dichlorodioctylstannane. The sensitising effects of DOTE can be disregarded as they are attributable to the ligand ETHG, which is not relevant for DOTC.