1,3-bis(hydroxymethyl)urea

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:

from 2011-07-28 to 2011-09-22

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

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: ISO 9439 Water Quality - Evaluation in an aqueous medium of the "ultimate" aerobic biodegradability of organic compounds - Method by analysis of released carbon dioxide.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Municipal activated sludge from the wastewater treatment plant of Mannheim, Germany
- Storage conditions: aerated antil use
- Storage length: 2 days
- Preparation of inoculum for exposure: A suitable aliquot of the activated sludge suspension was sieved by a finely woven mesh with a mesh size about 1 mm.
- Pretreatment: To reduce the content of inorganic carbon in the blank controls the activated sludge was aerated with carbon dioxide free air for about 48 hours at 22 ± 2° C.
- Concentration of sludge: 6.0 g/L dry weight
- Water filtered: yes
- Size of filter used: 1 mm

Duration of test (contact time):

28 d

Initial conc.:

71 mg/L

Based on:

TOC

Remarks:

20 mg TOC/L

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: as recommended in OECD 301B
- Test temperature: 22 ± 2 °C
- pH: 7.4 ± 0.2
- pH adjusted: yes
- Aeration of dilution water: yes
- Suspended solids concentration: 6.0 g/L dry weight
- Continuous darkness: yes/no

TEST SYSTEM
- Culturing apparatus: 2 L incubation bottles
- Number of culture flasks/concentration: 2 blank control assays, 2 test substance assays, 1 inhibition control test assay, 1 reference substance assay

Reference substance:

aniline

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 95 - <= 98

Sampling time:

28 d

Parameter:

% degradation (CO2 evolution)

Value:

9

Sampling time:

4 d

Parameter:

% degradation (CO2 evolution)

Value:

54

Sampling time:

14 d

Parameter:

% degradation (CO2 evolution)

Value:

92

Sampling time:

21 d

VALIDITY CRITERIA

Measured DIC-concentrations in the blank controls at begin of exposure (mean value): 0.6 mg/L

Amount of produced CO2 in the blank controls at the end of exposure (mean value): 16.1 mg/L

Deviation of the degree of biodegradation of the test substance in the plateau phase should be <20 %: yes

The degree of biodegradation of the reference substance should be >60 % CO2/ThCO2 after 14 days: yes

The degree of biodegradation in the inhibition control should be >25 % CO2/ThCO2 after 14 days: yes

The content of DIC in the blank control at start of exposure at the test concentration of 20 mg/L TOC should be <1 mg/L: yes

The amount of produced CO2 in the inoculum blank (“blank controls”) at the end of exposure (mean value) should be <70 mg/L: yes

DEGREE OF BIODEGRADATION

 

Duration of the adaptation phase: 4 days

Degree of biodegradation of the test substance at the end of the ten-day window: --

Degree of DOC removal of test substance at the end of exposure: 90-100 %

Degree of biodegradation of the test substance at the end of exposure, mean value: 90-100 % CO2/ThCO2

 

Reference substance: aniline

Degree of biodegradation of the reference substance after 14 days: 61 % CO2/ThCO2

Degree of biodegradation in the inhibition control after 14 days: 62 % CO2/ThCO2

Test temperature: 22 ± 2 °C

 

Test substance:

Total Organic Carbon (TOC): 282 mg/g

Reference substance: aniline

Stock solution, initial weight: 399.2 mg/L

Theoretical Organic Carbon (ThOC): 309 mg/L (calculated by inital weight)

 

Table 1. Degree of biodegradation; [% CO2/ThCO2]

Test duration [days]	RS	IH	TS1	TS2	TS mv
0 1 4 7 11 14 18 21 25 27 28	0 0 9 37 51 61 71 77 81 82 84	0 1 19 40 55 62 69 82 89 90 91	0 1 10 22 42 54 84 91 94 95 95	0 1 8 21 41 53 79 92 96 97 98	0 1 9 22 42 54 82 92 95 96 97

 

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The required pass level of degree of biodegradation of 60 % CO2/ThCO2 within 10 days was not reached, 54 % CO2/ThCO2 degradation at day 14 was measured. The degree of biodegradation after an exposure period of 28 days was 90 - 100 % CO2/ThCO2. The test item has a purity of 72 % and contains 28 % impurities. These impurities can contribute to a delayed degradation, thus, the 10-day window criterion is not relevant for a substance with different impurities. In addition, it is highly likely that at higher purity the test item will fulfill the set criterion for ready biodegradability as the obtained degradation at the end of the 10-day window was very close to the set criterion. As the test substance is only 72 % pure and contains big share of impurities, the 10-day window does not apply, therefore, the test item is considered as readily biodegradable.

Executive summary:

The ready biodegradability of the test substance was investigated in accordance with the EC 440/2008 Method C.4-C and OECD guideline 301 B: CO2 Evolution test (1992). The biodegradation of the test substance was followed by exposing it to microorganisms from the secondary effluent of a domestic waste water treatment plant over 28 days. The method assesses the ready biodegradability of a test substance under aerobic conditions at 22 ± 2 °C in the dark. During this period the biodegradation was determined on the basis of the removal of DOC. The degree of biodegradation was calculated by the amount of oxygen taken up by the test substance (corrected for that in the blank inoculum control) as a percentage of ThCO2 or CO2. As a reference compound (procedure control), aniline was tested simultaneously under the same conditions. In the procedure controls, the reference compound aniline was readily biodegraded by an average of 84 % after 28 days of exposure. At the end of the test (28 days), the test substance was biodegraded by an average of 90 - 100 %. The test item was degraded at 54 % after 14 days which is set as the end of the 10-day window. This value is very close to the set criterion for readily biodegradable substances – 60 % CO2/ThCO2 degradation in a 10-day window. As the substance contains around 28 % impurities, which can degrade outside of the set 10-day window, although, the test substance is regarded as mono-constituent substance; the 10-day window does not apply. At higher purity of the test item the set criterion for ready biodegradability in 10-day window is very likely to be fulfilled. Therefore, the test item is considered readily biodegradable in the CO2 evolution test.

Description of key information

The required pass level of degree of biodegradation of 60 % CO2/ThCO2 within 10 days was not reached, 54 % CO2/ThCO2 degradation at day 14 was measured. The degree of biodegradation after an exposure period of 28 days was 90 - 100 % CO2/ThCO2. The test item has a purity of 72 % and contains 28 % impurities. These impurities can contribute to a delayed degradation, thus, the 10-day window criterion is not relevant for a substance with different impurities. In addition, it is highly likely that at higher purity the test item will fulfill the set criterion for ready biodegradability as the obtained degradation at the end of the 10-day window was very close to the set criterion. As the test substance is only 72 % pure and contains big share of impurities, the 10-day window does not apply, therefore, the test item is considered as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The ready biodegradability of the test substance was investigated in accordance with the EC 440/2008 Method C.4-C and OECD guideline 301 B: CO2 Evolution test (1992). The biodegradation of the test substance was followed by exposing it to microorganisms from the secondary effluent of a domestic waste water treatment plant over 28 days. The method assesses the ready biodegradability of a test substance under aerobic conditions at 22 ± 2 °C in the dark. During this period the biodegradation was determined on the basis of the removal of DOC. The degree of biodegradation was calculated by the amount of oxygen taken up by the test substance (corrected for that in the blank inoculum control) as a percentage of ThCO2 or CO2. As a reference compound (procedure control), aniline was tested simultaneously under the same conditions. In the procedure controls, the reference compound aniline was readily biodegraded by an average of 84 % after 28 days of exposure. At the end of the test (28 days), the test substance was biodegraded by an average of 90 - 100 %. The test item was degraded at 54 % after 14 days which is set as the end of the 10-day window. This value is very close to the set criterion for readily biodegradable substances – 60 % CO2/ThCO2 degradation in a 10-day window. As the substance contains around 28 % impurities, which can degrade outside of the set 10-day window, although, the test substance is regarded as mono-constituent substance; the 10-day window does not apply. At higher purity of the test item the set criterion for ready biodegradability in 10-day window is very likely to be fulfilled. Therefore, the test item is considered readily biodegradable in the CO2 evolution test.