1-(2-aminoethyl)imidazolidin-2-one

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:

2015-10-20 until 2016-05-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Version / remarks:

July 17, 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

other: Secondary effluent, microorganisms from a domestic waste water treatment plant

Details on inoculum:

The inoculum: Secondary effluent, microorganisms from a domestic waste water treatment plant.
Origin: The secondary effluent was supplied from the sewage plant for domestic sewage in Veszprém, Hungary.
Conditioning: After collection of a fresh sample of secondary effluent it was allowed to settle for approximately one hour then filtrated through a coarse filter paper. Thereafter the filtrate was aerated until use.

Duration of test (contact time):

28 d

Initial conc.:

5 mg/L

Based on:

COD

Remarks:

The chosen test item concentration was based on the measured chemical oxygen demand (COD): 1.21 ±0.023 mg O2/mg test item and on the performed 14-d preliminary test.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: reconstituted water (OECD and EEC recommended) was prepared using deionised water and analytical grade reagents. see table below
- Test temperature: between 21°C and 23.1°C.
- pH: was measured before the beginning of the test in the mineral medium: 7.22
- pH adjusted: no
- Aeration of dilution water: The test medium was aerated for 20 minutes and allowed to stand for about 20 hours at the test temperature.
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: BOD bottles (300 ml) with special neck and glass stoppers.
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aeration, no more data
- Measuring equipment:
COD Measurement: The COD (chemical oxygen demand) of the test item was determined in the analytical department of the test facility using Lovibond® COD Measuring System.
Measurement of oxygen: The oxygen concentrations were measured with an oxygen meter with a stirring O2 electrode.
Measurement of total oxidised N, Nitrite and nitrate: During the performed 14-days preliminary test the concentration of dissolved oxygen resulted a mean of 7.25 mg O2/L after 14 days of incubation in the test item flasks (1a and 1b), which was nearly at the control level (7.30 mg O2/L), a mean of 0.8% biodegradation was noted within 14 days of the test item, therefore measurement of the total oxidised nitrogen (nitrate and nitrite) concentrations was not performed during the definitive study.
Measurement of temperature: Temperature was measured continuously and registered on weekdays.

SAMPLING : no data

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (2 replicates)
- Abiotic sterile control: no
- Toxicity control: yes (2 replicates)
- Other: group containing the reference item (3.6 mg/L) and inoculum (procedure control, 2 replicates)

STATISTICAL METHODS: none

Reference substance:

benzoic acid, sodium salt

Remarks:

(3.6 mg/L)

Preliminary study:

During the performed 14-days preliminary test the concentration of dissolved oxygen resulted a mean of 7.25 mg O2/L after 14 days of incubation in the test item flasks (1a and 1b), which was nearly at the control level (7.30 mg O2/L), a mean of 0.8% biodegradation was noted within 14 days of the test item, therefore measurement of the total oxidised nitrogen (nitrate and nitrite) concentrations was not performed during the definitive study.

Test performance:

All validity criteria were respected:
- Oxygen depletion in the inoculum control did not exceed 1.5 mg O2/L after 28 days.
- The residual oxygen concentration in the test flasks did not drop below 0.5 mg O2/L at any time.
- The difference of duplicate values for the degradation at any time during the test was less than 20 %.
- The percentage degradation of the reference item reached the level for ready biodegradability (> 60 %) within 14 days.
- The percentage degradation in the toxicity control containing both the test item and the reference item reached the level for ready biodegradability (> 25 %) by exposure day 14.

Parameter:

% degradation (O2 consumption)

Value:

5.8

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

5.8

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

7.4

Sampling time:

21 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

10.7

Sampling time:

28 d

Details on results:

Under the test conditions the percentage biodegradation of AEEU reached a mean of 10.7 % after 28 days based on the measured COD of the test item. Therefore the test item is considered not readily biodegradable.
According to the test guidelines the pass level for ready biodegradability is removal of 60 % ThOD.
In the toxicity control containing both, the test item and the reference item Sodium benzoate, a mean of 39.6% biodegradation was noted within 14 days and 38.4% biodegradation after 28 days of incubation.

Results with reference substance:

The reference item Sodium benzoate was sufficiently degraded to a mean of 75.0% after 14 days, and to a mean of 79.2 % after 28 days of incubation, based on ThODNH4, thus confirming the suitability of the used inoculum.

Table 1. Dissolved Oxygen Concentrations at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration	Flask	mg O2/L after n days of exposure
	[mg/L]	No.	0	7	14	21	28
Test item		1a	8.5	7.2	7.1	7.1	6.5
	5.0	1b	8.4	7.2	7.1	7.0	6.6
		mean	8.45	7.20	7.10	7.05	6.55
Reference item		2a	8.5	4.1	2.9	2.6	2.5
	3.6	2b	8.5	4.1	3.1	2.6	2.5
		mean	8.50	4.10	3.00	2.60	2.50
Inoculum control	–	3a	8.5	7.6	7.5	7.5	7.2
		3b	8.5	7.6	7.5	7.6	7.3
		mean	8.50	7.60	7.50	7.55	7.25
Toxicity control	Test item: 5.0 Reference item: 3.6	4a	8.5	4.0	2.6	2.5	2.5
		4b	8.5	4.1	2.6	2.5	2.5
		mean	8.50	4.05	2.60	2.50	2.50

 

Table 2.Oxygen Depletion at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration	Flask	mg O2/L after n days of exposure
	[mg/L]	No.	7	14	21	28
Test item	5.0	1a	0.40	0.40	0.45	0.75
		1b	0.30	0.30	0.45	0.55
Reference item	3.6	2a	3.50	4.60	4.95	4.75
		2b	3.50	4.40	4.95	4.75
Toxicity control	Test item: 5.0 Reference item: 3.6	4a	3.60	4.90	5.05	4.75
		4b	3.50	4.90	5.05	4.75

 

oxygen depletion : (mt0 - mtx) - (mb0 - mbx), where:

mt0 : oxygen concentration (mg/L) of test group on day 0 (1a, 2a, 4a and 1b, 2b, 4b from Table 1)

mtx: oxygen concentration (mg/L) of test group on day x (1a, 2a, 4a and 1b, 2b, 4b from Table 1)

mb0: oxygen concentration (mg/L) of inoculum blank on day 0 (mean of 3a and 3b from Table 1)

mbx: oxygen concentration (mg/L) of inoculum blank on day x (mean of 3a and 3b from Table 1)

 

Table 3.BOD at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration	Flask	BOD after n days of exposure
	[mg/L]	No.	7	14	21	28
Test item	5.0	1a	0.08	0.08	0.09	0.15
		1b	0.06	0.06	0.09	0.11
Reference item	3.6	2a	0.97	1.28	1.38	1.32
		2b	0.97	1.22	1.38	1.32
Toxicity control	Test item: 5.0 Reference item: 3.6	4a	0.42	0.57	0.59	0.55
		4b	0.41	0.57	0.59	0.55

 

BOD = (mg O2 uptake/L of T.i. and/or R.i.-mg O2 uptake/L of i.control) / (mg T.i. and/or R.i./L in flask) = mg O₂uptake/mg T.i and/or R.i.

where:

T.i.  =  test item

R.i.  =   reference item

i.control  =  inoculum control

Table 4. Percentage Biodegradation at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration	Flask	Percent of biodegradation after n days of exposure
	[mg/L]	No.	7	14	21	28
Test item		1a	6.6	6.6	7.4	12.4
	5.0	1b	5.0	5.0	7.4	9.1
		mean	5.8	5.8	7.4	10.7
Reference item		2a	58.3	76.7	82.5	79.2
	3.6	2b	58.3	73.3	82.5	79.2
		mean	58.3	75.0	82.5	79.2
Toxicity control	Test item: 5.0 Reference item: 3.6	4a	29.1	39.6	40.8	38.4
		4b	28.3	39.6	40.8	38.4
		mean	28.7	39.6	40.8	38.4

Biodegradation % = (BOD (mg O2/mg T.i. or R.i.)) / (COD (mg O2/mg T.i.) or ThOD NH4 (mg O2/mg R.i.)) x 100

where:

T.i.  =  test item

R.i.  =  reference item

i.control =  inoculum control

 

COD of test item= 1.21 ± 0.023 mg O₂/mg test item

ThOD_NH4of reference item = 1.67 mg O₂/mg reference item

 

The biodegradation in the toxicity control was calculated according to the following formula:

(BOD (mg O2/mg T.i. or R.i.)) / ((COD (mg O2/mg T.i.) + ThOD NH4 (mg O2/mg R.i.)*1/2)) x 100

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Under the test conditions the percentage biodegradation of AEEU reached a mean of 10.7 % after 28 days based on the measured COD of the test item. Therefore the test item is considered not readily biodegradable.

Executive summary:

The test item AEEU was investigated for its ready biodegradability in a Closed Bottle Test (OECD 301 D) over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item Sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. The test system was a microbial inoculum of good quality, derived from a sample of secondary effluent taken from the aeration tank of a domestic waste water treatment plant. Under the test conditions the percentage biodegradation of AEEU reached a mean of 10.7 % after 28 days based on the measured COD of the test item. Therefore the test item is considered not readily biodegradable. According to the test guidelines the pass level for ready biodegradability is removal of 60 % ThOD.

Description of key information

AEEU attained 10.7% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301D.

Additional information

A GLP-compliant study, scored as Klimisch 1 and flagged as a key study, is available on AEEU, giving 10.7% degradation after 28 days (OECD Guideline No 301D) and revealing that AEEU cannot be considered to be readily biodegradable (K. Sipos, 2016).