Dibutyldimethoxystannane

Biodegradation in water: screening tests

Description of key information

A weight of evidence approach was taken concerning the biodegradation of dibutyl dimethoxystannane. As no data was available on the substance itself, appropriate read-across substances were employed. As all dibutyltins are anticipated to hydrolyse to the oxide form in water, dibutyltin dilaurate and dibutyltin maleate were considered acceptable to read-across for this endpoint.
Hanstveit 2003 (dibutyltin maleate): The test substance disbutylbis[(1-oxododecyl)oxy]stannane was biodegraded 23% in a manometric respiration test at a test concentration of 22.2 mg/L after 39 days of incubation.  Based on these results, disbutylbis[(1-oxododecyl)oxy]stannane is considered not ready biodegradable.
Hanstveit 2003 (dibutyltin dilaurate): The percentage degradation of 1,3,2-dioxastannepin-4,7-dione, 2,2-dibutyl- after 28 days of incubation was approximately 3% in a manometric respiration test at a test substance concentration of 37.7 mg.l-1, calculated from the ThODNH3 (1.38 mg O2.mg-1) of test substance. The biodegradation of 1,3,2-dioxastannepin-4,7-dione, 2,2-dibutyl- did not exceed the pass level of 60% ThODNH3 within 28 days and, therefore, is classified as not readily biodegradable. 

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Read-across from dibutyltin oxide to dibutyl dimethoxystannane concerning biodegradation in water was considered appropriate as dibutyltin and octyltins are known to hydrolyse rapidly in water (as presented by Yoder 2003, under the data requirement hydrolysis), and form, in the case of dibutyltins, dibutyltin oxide.