2,2,4-trimethyl-1-oxa-4-aza-2-silacyclohexane

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

adopted July 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Purity : 98.6 %

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Origin : aeration tank of a wastewater plant treating predominantly domestic sewage (Wupper area water authority, WWTP Odenthal)
Date of collection : 2016-10-04
Concentration of inoculum : 30 mg/L suspended solids

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

BOD

Details on study design:

A suspension of 100 mg/L test item in a mineral medium, equalling to 50-100 mg ThOD or COD/Litre as the nominal sole source of organic carbon, was stirred in a closed flask and inoculated at a constant temperature (22 ± 1 °C) for up to 28 days under aerobic conditions in the dark.
The consumption of oxygen (BOD) was determined by measuring the drop in pressure in the automated respirometer flasks. Evolved carbon dioxide was absorbed in sodium hydroxide. The amount of oxygen taken up by the test item (corrected for uptake by blank inoculum, run in parallel) was expressed as a percentage of theoretical oxygen demand (ThOD).
The endogenous activity of the inoculum was checked running parallel blanks with inoculum but without test item. A reference compound (sodium benzoate) was run in parallel to check the operation of the procedures.
A toxicity control (test item and reference compound mixed, one replicate) was run in parallel, to ensure that the chosen concentration of the test item was not inhibitory to microorganisms.
Degradation was followed by the determination of oxygen uptake and measurements were taken at frequent intervals to allow the identification of the beginning and end of biodegradation and the slope of the biodegradation curve.
Because of the nature of biodegradation and of the mixed bacterial populations used as inoculum, determinations of test item and inoculum blank were carried out in triplicate and of reference compound in duplicate.
The oxygen uptake was calculated from the readings taken at regular and frequent intervals, using the method given by the manufacturer of the equipment. At the end of incubation, the pH was measured in the flasks.
Start of the incubation period : 2016-10-05
End of the incubation period : 2016-11-03

Reference substance:

benzoic acid, sodium salt

Remarks:

Reference compound name : sodium benzoate (Acros Organics) Coding number : Ökotox_7/02 Purity : 99.9 % Expiry date : 2018-03-27

Parameter:

% degradation (O2 consumption)

Value:

1

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

1

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

2

Sampling time:

21 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

28 d

Parameter:

BOD5

Value:

>= 3.6 - <= 12 mg O2/g test mat.

Remarks on result:

other: blank-corrected BOD

Remarks:

Test concentration : 100 mg/L Theoretical oxygen demand : 2.321 mg O2/mg

Results with reference substance:

Test concentration : 100 mg/L
Theoretical oxygen demand : 1.665 mg O2/mg
blank-corrected BOD after 28 days: 147.4 mg O2/L
degradation mean: 88%

Validity criteria fulfilled:

yes

Remarks:

All validity criteria of the test method were met.

Interpretation of results:

not readily biodegradable

Conclusions:

2,2,4-Trimethyl-1-oxa-4-aza-2-silacyclohexane showed 3 % degradation after 28 day in a manometric respirometry test. Test item is considered to be “Not Readily Biodegradable“.

Executive summary:

A study was performed to assess the ready biodegradability of 2,2,4-Trimethyl-1-oxa-4-aza-2-silacyclohexane in accordance with OECD Guideline 301 F.

A suspension of 2,2,4-Trimethyl-1-oxa-4-aza-2-silacyclohexane in a mineral medium was inoculated and incubated for 28 d under aerobic conditions. During this period, degradation was followed by continuous automated BOD determinations.

2,2,4-Trimethyl-1-oxa-4-aza-2-silacyclohexane showed:

1 % degradation after 7 days

1 % degradation after 14 days

2 % degradation after 21 days

3 % degradation after 28 days

2,2,4-Trimethyl-1-oxa-4-aza-2-silacyclohexane is considered to be “Not Readily Biodegradable“.

Description of key information

A study was performed to assess the ready biodegradability of 2,2,4-Trimethyl-1-oxa-4-aza-2-silacyclohexane in accordance with OECD Guideline 301 F.

A suspension of 2,2,4-Trimethyl-1-oxa-4-aza-2-silacyclohexane in a mineral medium was inoculated and incubated for 28 d under aerobic conditions. During this period, degradation was followed by continuous automated BOD determinations.

2,2,4-Trimethyl-1-oxa-4-aza-2-silacyclohexane showed 3 % degradation after 28 days.

2,2,4-Trimethyl-1-oxa-4-aza-2-silacyclohexane is considered to be “Not Readily Biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed