Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

A single reliable study investigating the hydrolysis of the dimethyltin dichloride (DMTC) has been found to be available. In that study, which was conducted according to OECD Guideline 111, the percentage hydrolysis of DMTC was less than 10% after incubation in buffer solutions pH 4.0, pH 7.0 and pH 9.0 and in Milli-Q water, for 5 days at 50 °C. A secondary reference (Bertolo (2001)) was discovered however it has not been possible to obtain the full report. That report that makes note that whilst the dimethyltin substance is hydrolytically stable, the substance itself is not. Given that the full study has not been reviewed this information is regarded as supporting. Therefore, based on the result of the key study, DMTC was considered hydrolytically stable and no further testing was performed.

The ready biodegradability of DMTC was investigated in line with OECD Guideline 301F using oxygen consumption as the test criterion. The test was extended to 35 days because the plateau phase had not been reached after 28 days of incubation. DMTC was not degraded. Consequently, the 60% degradation criterion was not met and therefore it was considered not readily biodegradable under the specific conditions of this test. Further biotic degradation tests on DMTC were considered unnecessary. The substance is considered to be of no immediate concern to the environment and the available data were found to be adequate both for classification and labelling purposes and for PBT assessment. Adaptations from the standard data requirements were submitted to address the individual endpoints.

No high quality data that addressed the substance's bioaccumulation potential were available and the existing studies were summarised only for the sake of completeness. These suggested that the BCF of the substance may range from 1.6 to 50. Given that the substance is reported to have a high water solubility (823 g/L at 20 °C) coupled with a very low octanol-water partition coefficient (log Kow: -2.18) and that no significant environmental exposure is expected it was considered justified to waive further testing to investigate this endpoint.