Dibutyldimethoxystannane

Endpoint summary

Additional information

Limited data on the substance is available.

A reliable micronucleus in-vivo assay of the dibutyltin chloride was reported as positive, but a second less reliable micronucleus assay as negative.

Based on the available data and considering the proposed EU classification of Dibutyltin salts are recommended for classification as mutagenic (R68). An SPCFC (2004) review of organotins concluded that (organotins in general) did not exhibit any significant genotoxic potential in vivo, and that carcinogenicity seen with some organotin compounds was likely attributable to hormonal or immunotoxic action. However, the available data for the dibutyltin substance as described above are inadequate to challenge that recommendation.

A read-across approach was considered appropriate from dibutyltin chloride to other dibutyltins. Under gastric conditions dibutyltins are hydrolysed to form dibutyltin chloride. This is demonstrated in various dibutyltin compounds presented in the TNO report V5047, (presented as individual reports as under Toxicokinetics).

Short description of key information:
The following data have been submitted to address the in vivo genetic toxicity endpoint:

Dance (1991) Dibutyl tin chloride: assessment of clastogenic action on bone marrow erythrocytes in the micronucleus test. Report number: 91/0357. Report date: 1991-11-08

Lang and Wedel (1990) Studies on the mutagenic potential of ZK 22.663 in the mouse micronucleus test. Report number: IC 9/90. Report date: 1990-02-13.

Both studies have been allocated a Klimisch score of 2 but Dance (1991) has been allocated as the key study because it has been performed in line with GLP to recognised guidelines.

All studies were performed on dibutyltin dichloride to read-across to the substance in question. As dibutyltins rapidly undergo hydrolysis the results are expected to be representative of all dibutyltin compounds.

Endpoint Conclusion: Adverse effect observed (positive)

Justification for classification or non-classification

According to directive 67/548/EEC the substance is assigned the classification Mutagenicity category 3 and labelled with R68 – possible risk of irreversible effects. According to Regulation (EC) no 1272/2008 the test substance would be classified as Muta. 2 with the Hazard statement: H341: Suspected of causing genetic defects and should be accompanied with the signal word 'Warning'.