Dioctyltin dilaurate

Biodegradation in water: screening tests

Description of key information

The substance to be registered was shown to hydrolyses to dioctyltin oxide and lauric acid. Therefore, since no information on the biodegradation of the substance is available, information on the ready biodegradability of dioctyltin oxide has been included together with information on sodium laurate, the read across substance of lauric acid. Both substances were concluded to be 'not readily biodegradable'.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Since no data are available on the substance itself information has been addressed on a weight of evidence basis, reading across to a product of its hydrolysis, dioctyltin oxide, and a structural analogue of another hydrolysis product, sodium laurate.

The ready biodegradability of dioctyltin oxide (Hanstveit, 2003) was assessed in a Manometric Respirometry test conducted in accordance with OECD guideline 301F and EU Method C.4 -D and to GLP. Under the conditions of the test, dioctyltin oxide degraded approximately 2 % within 28 days of incubation with activated sludge. Two of the flasks performed with the dioctyltin oxide gave negligible oxygen consumption, whilst the third gave 8 % within 28 days. Furthermore dioctyltin oxide exhibited no toxic effect on the inoculum. Therefore, under the conditions of the study, dioctyltin oxide can be categorised as not readily biodegradable.

The Environmental Risk Assessment report (2003) included a BOD5 value for ready biodegradation of sodium laurate. The value was reported as 58 %. Therefore, under the conditions of the study, sodium laurate can also be categorised as not readily biodegradable. The data was taken from a secondary source, and as such no information on materials and methods are available.