Bis(4-(1,1,3,3-tetramethylbutyl)phenyl) ether

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:

June 08, to July 07, 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Version / remarks:

adopted by Council on 26th November 1997

Deviations:

yes

Remarks:

Temperature range was 19.4 – 21.0 °C instead of 20.0 – 24.0 °C. As degradation of the positive control was in the normal range this is considered as uncritical concern-ing the outcome of the study.

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Version / remarks:

adopted 30. May 2008

Deviations:

yes

Remarks:

Temperature range was 19.4 – 21.0 °C instead of 20.0 – 24.0 °C. As degradation of the positive control was in the normal range this is considered as uncritical concern-ing the outcome of the study.

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, 67435 NW-Lachen-Speyerdorf. Date of collection: 05. May 2020, batch no: E20200605.
- Pretreatment: The sludge was filtrated through a cloth, washed with test medium (2x) and re-suspended in test medium. It was then aerated until use. The dry matter was determined to contain 4.4 g of suspended solids/L.

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
- Additional substrate:
- Test temperature: 19.4 – 21.0 °C without direct lighting
- pH: 6.9 - 7.6

TEST SYSTEM
- Culturing apparatus: Flask volume 1500 mL
- Number of culture flasks/concentration: 2
- Measuring equipment: The emitted CO2 was trapped in 0.25 M NaOH. Two scrubbers containing 100 mL each were connected in series to the test vessels.

SAMPLING
Analyses of the emitted CO2 were made by IC measurement using the carbon analyser TOC multi N/C 2100S, Analytik Jena. Each sample was measured in duplicate or triplicate, respectively (depending on the variation between the measured values).
- Sampling frequency: 10 samples were taken in order to determine the emitted CO2 (on day 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29). The sample volume was 1 mL.

CONTROL AND BLANK SYSTEM
- Apparatus blank: 2, containing mineral medium only
- Blank Controls: 2, containing mineral medium and inoculum
- Positive control flasks: 2, containing positive control, mineral medium and inoculum
- Abiotic sterile control: 1, containing test item, mineral medium and HgCl2
- Toxicity control: 1, containing test item, positive control, mineral medium and inoculum

Reference substance:

aniline

Remarks:

23.9 mg/L TOC

Key result

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

28 d

Results with reference substance:

Degradation 82.7% after 28 days

Degradation Values [%]:  

Day	Positive Control 1	Positive Control 2	Positive Control Mean	Test 1	Test 2	Test Mean	Abiotic Control	Toxicity Control
2	0.2	2.8	1.5	0.6	1.1	0.8	0.8	1.9
4	1.7	-0.4	0.6	-0.6	-1.1	-0.8	1.9	2.8
7	40.6	42.7	41.7	-3.2	0.7	-1.2	0.9	24.1
9	59.3	64.9	62.1	-4.0	0.4	-1.8	0.9	34.2
11	65.3	70.8	68.0	-1.9	0.9	-0.5	0.9	34.7
14	76.4	80.4	78.4	-3.0	1.0	-1.0	0.7	40.8
18	80.1	82.3	81.2	-3.4	2.5	-0.5	1.1	42.3
23	78.1	79.3	78.7	-2.8	2.0	-0.4	1.1	39.7
29	82.1	83.2	82.7	-1.6	1.3	-0.2	0.7	39.6

As the measured IC values in the test flasks are very low, measurement uncertainties lead to negative degradation values while in fact no degradation has taken place.

Degradation behaviour of positive control and toxicity control was normal. Abiotic degradation reached 0.7 %. Both replicates of the test item showed very good correspondence.

As degradation in the toxicity flask was 40.8 % after 14 days, the test item can be stated as “not toxic towards the inoculum in a concentration of 23.3 mg/L”. 

 

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test item is considered as not readily biodegradable and not ultimately biodegradable, within 28 days.

Executive summary:

The test item Bis(4-(1,1,3,3-tetramethylbutyl)phenyl)ether was tested using a concentration of nominally 20 mg organic carbon/LBis(4-(1,1,3,3-tetramethylbutyl)phenyl)ether in test medium following OECD 301B and EU-Method C.4-C.

 

Aniline was chosen as positive control.

Activated sludge was used as inoculum (concentration in the test 25.0 mg dry matter/L). The test was left running for 28 days.

All validity criteria were met. Degradation of the positive control surpassed the pass level of 60 % after 9 days.

 

For the test item Bis(4-(1,1,3,3-tetramethylbutyl)phenyl)ether no biodegradation was observed after 28 days. The 10-day window could not be determined. The criterion of reaching 60% of degradation after 28 days is not met. Bis(4-(1,1,3,3-tetramethylbutyl)phenyl)ether is therefore considered as not readily biodegradable and not ultimately biodegradable, within 28 days.

Description of key information

The test item Bis(4-(1,1,3,3-tetramethylbutyl)phenyl)ether was tested using a concentration of nominally 20 mg organic carbon/LBis(4-(1,1,3,3-tetramethylbutyl)phenyl)ether in test medium following OECD 301B and EU-Method C.4-C.

For the test item Bis(4-(1,1,3,3-tetramethylbutyl)phenyl)ether no biodegradation was observed after 28 days. The 10-day window could not be determined. The criterion of reaching 60% of degradation after 28 days is not met. Bis(4-(1,1,3,3-tetramethylbutyl)phenyl)ether is therefore considered as not readily biodegradable and not ultimately biodegradable, within 28 days.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater