Registration Dossier

Environmental fate & pathways

Hydrolysis

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Link to relevant study record(s)

Description of key information

A new Key study was added to the dossier which shows that the substance can be considered as hydrolytically stabel at high pH (4 /  7 / 9).
The substance hydrolyses rapidly to it's monochloride at simulated gastric conditions (pH 1.2 / 37 °C / 30 seconds - 8 hours)
Quantitative 119Sn-NMR spectroscopy has been used as a valuable analytical tool to directly identify and quantify all organotin components, which are formed as a result of hydrolysis of the tested substance.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 yr
at the temperature of:
25 °C

Additional information

The study showed that DBT-MPTD at pH 9, 7 and 4 can be considered hydrolytically stable. After 5 days at 50 °C less than 10% DBT-MPTD was hydrolyzed (t 0.5 25°C > 1 year).

Under the simulated gastric conditions (0.1 M HCl / pH 1.2 / 37 °C) DBT-MPTD was hydrolyzed to DBTC-MPTD, its monochloro ester.

It can be concluded that DBTC-MPTD is the only metabolite of DBT-MPTD that was formed in the simulated mammalian gastric environment. No DBTC was formed under the conditions of this study.

The previous key study, Butler & White (2010), as the study with the surrogate substance Dibutyltin bis(2-ethylhexlmercaptoacetate), DBTE, was disregarded since in the new key study no DBTC was formed, on which the Butler study is based.