Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

TAEE is not readily biodegradable in the aquatic environment according to a GLP-compliant standardised aerobic ready-biodegradation test (OECD 301D guideline; Closed Bottle test).The percentage of biodegradation observed is ca. 5% after 28 days.Therefore, TAEE should be classified as “not biodegradable”. However, certain adapted micro-organisms are capable of degrading the structurally related aliphatic ether TAME (Kharoune et al., 2002). These studies show that at least some microbial species are capable to degradethe structurally related aliphatic ether TAME and to use it even as their sole carbon source.It may be concluded that TAEE is inherently biodegradable under certain conditions in the aquatic aerobic environment. In contrast, adapted sewage sludge is able to rapidly degrade TAEE.

Therefore, a distinction will be made between biodegradation in non-adapted municipal STPs which will be classified as“inherently biodegradable, not fulfilling criteria”and adapted industrial STPs where there are continuous releases of TAEE which will be classified as “readily biodegradable”. For these adapted STPs, Monod kinetics are used for the degradation of TAEE in the STP instead of the more simplified first-order kinetics.

No simulation tests are available for TAEE, but data are available for the structurally related aliphatic ether TAME.In anaerobic, static sediment/water microcosms, TAME does not biodegrade (Suflita and Mormile, 1993; Mormile et al., 1994; Somsamak et al., 2001).Based on the few studies available it should be concluded that rapid and reliable biodegradation of TAME in soil can not be assumed in any normal environmental conditions indicating very slow degradation in soil (Jensen and Arvin, 1990; Mormile et al., 1994; Zenker et al., 1999). The biodegradability of TAME in soil in aerobic and anaerobic conditions seems to be very slow and favourable conditions for degradation are difficult to attain.

The biotic degradation rate constants used in the assessment are:

Degradation in a non-adapted STP

0 d-1

Degradation in an adapted STP

Monod kinetics (default values)

Degradation rate in surface water

0 d-1

Degradation rate in aerated sediment

1.31·10-6d-1

Degradation rate in soil

1.31·10-6d-1