Reaction mass of diethyl adipate and diethyl glutarate and diethyl succinate

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:

10/05/2017-16/11/2017

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)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

Activated sludge, municipal wastewater treatment plant, Breisgauer Bucht, 30 mg dry solids per litre. The treatment plant clarifies predominantly domestic wastewater and has a capacity of 600.000 inhabitant equivalents. Sampling date of activated sludge was on 7 August 2017. The dry solid content of the activated sludge was 3.9 g/L. It was determined by weight measurements after drying at 105°C for 4 hours (mean of triplicate measurements). The activated sludge was washed twice with tap water by settling the sludge, decanting the supernatant and re-suspending the sludge.

Duration of test (contact time):

28 d

Initial conc.:

> 10 - < 20 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

In total three reactors containing the test item, three reactors containing only inoculum (blank), three reactors containing the reference compound and one reactor containing test item and
reference compound (toxicity control) were set up.

- Test item:
The test item was pipetted directly into the test vessels. 50.6 μL were pipetted into the test vessels, corresponding to a test concentration of 20.0 mg/L organic carbon.
- Reference substance:
A stock solution of 10.0 g/L sodium benzoate in water was prepared. 5.15 mL of this stock solution were added into the reference vessels corresponding to a concentration of mg/L organic carbon.
- Toxicity control:
50.6 μL of the test item and 5.15 mL of the reference stock solution (10 g/L) were added to the toxicity control vessel corresponding to a concentration of 40.0 mg/L organic carbon.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

76.5

Sampling time:

28 d

Remarks on result:

other: mean of the 3 flasks

Details on results:

The degradation extent of the test item at the end of the test was 76.5% (28 d after acidification, mean of three replicates. A mean degradation of >60% was measured on day 7 and was thus reached within a 10d-window.
The degradation extent in the toxicity control was 78.2% within 14 days, the test substance had no inhibitory effect on the inoculum.

Results with reference substance:

The reference compound sodium benzoate reached the pass level for ready biodegradability within 3 days

Table 1: Ultimate biodegradation after x days (% of ThCO2)

reactor	day	0	3	7	10	14	21	28	29
7 8 9	Test flasks	0	48.7	71.8	76.0	83.6	84.0	88.0	88.5
		0	38.2	64.0	69.1	74.3	75.7	72.4	70.5
		0	42.0	68.8	67.5	68.8	70.3	69.4	70.6
4 5 6	reference flasks	0	65.8	80.3	86.0	88.0	96.4	101.0	101.9
		0	58.4	76.7	77.6	77.5	84.6	89.2	88.9
		0	66.2	73.3	78.6	77.8	80.2	77.7	76.2
10	Toxicity control Testitem Reference item	0	36.6	64.6	75.1	78.2	85.1	84.7	85.6

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item reached the criteria for ready biodegradability (60% of ThCO2 within a 10-d window).

Executive summary:

A CO2 Evolution Test according to OECD 301 B (July 1992) was conducted in order to investigate the ready biodegradability of Reaction mass of diethyl adipate and diethyl glutarate and diethyl succinate. The degradation extent of the test item at the end of the test was 76.5% after 28 days (after acidification, mean of three replicates). A mean degradation of >60% was measured on day 7 and was thus reached within a 10d-window. Therefore the test item reached the criteria for ready biodegradability (60% of ThCO2 within a 10-dwindow).

Description of key information

The ready biodegradability of the test item was investigated in a GLP-compliant ready biodegradability screening study performed in accordance with OECD Guideline No. 301B. The degradation of the test item at the end of the test was 76.5% (based on ThCO2) after 28 days. The test item reached the criteria for ready biodegradability according to the OECD criteria (≥ 60% ThOD and fulfilment of the 10-d window). The test item is thus considered "readily biodegradable".

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The ready biodegradability of the test item was investigated in one GLP-compliant study performed in accordance with OECD Guideline No. 301B, without deviations. The study is considered as reliable (Klimisch 1) and is selected as a key study for the endpoint.