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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From February 15, 2006 to July 14, 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
- Name of test material (as cited in study report): Flotigam K2C (dry residue)
- Physical state: Colourless, wax-like solid
- Analytical purity: 98%
- Composition of test material, percentage of components: Dicocosalkyl dimethyl ammoniumchloride- 98 %
- Lot/batch No.: DEGE141103
- Expiration date of the lot/batch: August 2007
- Stability under test conditions: Stable (ca. 0.1% aqueous solution)
- Storage condition of test material: Room temperature, protected from moisture and light.
- Other:
- Soluble in water at 20°C.
- pH value = 5.3 (1% a.i. in water)
- Density = ca. 0.9g/cm3 at 20°C
- TOC= 73%
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Municipal sewage treatment plant, D-31137 Hildesheim
- Storage conditions: in an aerobic condition by aeration with CO2 free air.
- Storage length: 7 d
- Pretreatment: The activated sludge was washed twice with autoclaved tap water. After the second washing the settled sludge was filled up with mineral salts medium and was maintained in an aerobic condition by aeration with CO2-free air for 7 days. 10ml/L were used to initiate inoculation.
- Initial cell/biomass concentration: 10E7 - 10E8 CFU/L
- Water filtered: no
Duration of test (contact time):
28 d
Initial conc.:
10 mg/L
Based on:
test mat.
Initial conc.:
20 mg/L
Based on:
other: humic acid
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral salts medium according to OECD 301 B/CO2 Evolution Test.
- Test temperature: 22±2°C
- Aeration of dilution water: 30 - 100 mL/min
- Continuous darkness: no (low-light conditions)
- Other:
- Dispersion treatment: Continuously stirring.


TEST SYSTEM
- Culturing apparatus: 5000 mL brown glass bottles
- Number of culture flasks/concentration: 2 for test item concentration, 1 for the reference item, 2 for the inoculum control, 1 for the toxicity control and 2 for the humic acid control.
- Measuring equipment: pH-meter, Thermohygrograph, type 3.015/3 K, Flow meter, Analytical balance, Balance, Ultrasound.


SAMPLING
- Sampling frequency: The room temperature was measured continuously by a thermohygrograph. Determination of CO2 was carried out by titration subsequent to complete adsorption of the released CO2 in an alkaline solution (0.0125 mol/L Ba(OH)2). Back titration of the residual Ba(OH)2 with 0.05 N HCl was carried out three times a week during the first ten days and thereafter twice weekly. On day 28, the pH value of all solutions was measured prior to acidification.


CONTROL AND BLANK SYSTEM
- Inoculum blank: Mineral salts medium
- Abiotic sterile control: Mineral salts medium +20 mg/L humic acid
- Toxicity control: Test item and reference item in test concentration + 20 mg/L humic acid.


STATISTICAL METHODS: No data
Reference substance:
benzoic acid, sodium salt
Preliminary study:
No data
Test performance:
No data
Key result
Parameter:
% degradation (CO2 evolution)
Value:
61
Sampling time:
28 d
Remarks on result:
other: The value reported is the mean biodegradation, calculated from the 2 replicates of test item.
Details on results:
- In the toxicity control 50 % biodegradation occurred within 14 d and came to 67 % after 28 d. The biodegradation of the reference item was not inhibited by the test item.
- The mean biodegradation of the test item was 61 %. The 10 % level (beginning of biodegradation) was reached by the 1st test item replicate after 12 d, by the 2nd replicate after 6 d. The 2nd test item replicate reached the pass level of 60% after 26 d and came to 66% after 28 d. The 1st replicate came to 56% after 28 d.
- The test material is regarded as biodegradable after 28 d. The test item complies with the biodegradability criteria as laid down in Annex III of Regulation (EC) No 648/2004 on detergents.
Results with reference substance:
The adaptation phase of the functional control changes after 2 d into the degradation phase (degradation ≥ 10 %). The course of the degradation phase is rapid and reaches a degradation rate of 60 % after 7 d. The degradation came to 100 % after 14 d. The validity criterion degradation ≥ 60 % after 14 d is fulfilled.

CO2 -Production and Biodegradation

The total amount of CO2 produced in 28 d was analysed by titration in 12 measurements. The 28 d values are shown in comparison to the readily degradable functional control in summarized form in Table 1.

Table 1: CO2-Production and Biodegradation after 28 d 

CO2 production

After 28 d

Control

Mv

Functional

Control

20 mg/L

Humic acid

control

Test item

10 mg/L

No 1

Test item

10 mg/L

No. 2

Toxicity

Control

20 + 10 mg/L

Gross [mg/ 3 L]

          [mg/L]

169.0

56.3

-

172.8

57.6

-

-

-

Net     [mg/ 3L]

          [mg/L]

-

-

151.4

50.5

-

-

45.3

15.1

53.2

17.7

140.0

46.7

Theor. [mg/ 3L]

          [mg/L]

-

-

127.8

42.6

-

-

80.4

26.8

80.4

26.8

208.2

69.4

Degradation [%]

After 28 d

-

100

-

56

66

67

In the control a maximum of 56.3 mg CO2/L and in the humic acid control 57.6 mg CO2/L were formed after 28 d (validity criterion: 70 mg CO2 /L after 28 d).

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Under the test conditions, test material (containing 98 % dicocosalkyldimethylammoniumchloride) was considered as readily biodegradable after 28 d.
Executive summary:

The biodegradability was determined with a non adapted activated sludge for the test material (containing 98 % dicocosalkyl dimethylammonium chloride) over a test period of 28 d in the Modified Sturm Test. The study was conducted according to OECD 301 B / CO2 evolution test.

The test material was tested with a concentration of 10 mg/L in duplicates, corresponding to carbon content (TOC) of 7.3 mg C/L in the test vessels. To reduce the toxicity of the test material 20 mg/L humic acid was added to the test item and toxicity control replicates. The biodegradation of the test material was followed by titrimetric analyses of the quantity of CO2 produced by the respiration of bacteria. The degradation was finished on Day 28 by acidification and the last titration was made on Day 29, after the soluble CO2 was turned out over a period of 24 h. The percentage CO2 production was calculated in relation to the theoretical CO2 (ThCO2) of the test material.

Sodium benzoate was used as functional control. The percentage degradation of the functional control reached the pass level of 60 % after 7 d. The degradation came to 100 % after 14 d. In the toxicity control containing both test and reference item a biodegradation rate of 50 % occurred within 14 d and came to 67 % after 28 d. The biodegradation of the reference item was not inhibited by the test item in the toxicity control. The 10 % level (beginning of biodegradation) was reached by the 1st replicate after 12 d, by the 2nd replicate after 6 d. The 2nd replicate reached the pass level of 60 % after 26 d and came to 66 % after 28 d. The 1st replicate came to 56 % after 28 d. The mean biodegradation came to 61 % after 28 d. The validity criteria according to the guideline are fulfilled.Under the test conditions, test material (containing 98 % dicocosalkyl dimethyl ammonium chloride) was considered as readily biodegradable after 28 d (Fiebig S, 2006).

Description of key information

The biodegradability was determined with a non adapted activated sludge for the test material (containing 98 % dicocosalkyl dimethylammonium chloride) over a test period of 28 d in the Modified Sturm Test. The study was conducted according to OECD 301 B / CO2 evolution test.

The test material was tested with a concentration of 10 mg/L in duplicates, corresponding to carbon content (TOC) of 7.3 mg C/L in the test vessels. To reduce the toxicity of the test material 20 mg/L humic acid was added to the test item and toxicity control replicates. The biodegradation of the test material was followed by titrimetric analyses of the quantity of CO2 produced by the respiration of bacteria. The degradation was finished on Day 28 by acidification and the last titration was made on Day 29, after the soluble CO2 was turned out over a period of 24 h. The percentage CO2 production was calculated in relation to the theoretical CO2 (ThCO2) of the test material.

Sodium benzoate was used as functional control. The percentage degradation of the functional control reached the pass level of 60 % after 7 d. The degradation came to 100 % after 14 d. In the toxicity control containing both test and reference item a biodegradation rate of 50 % occurred within 14 d and came to 67 % after 28 d. The biodegradation of the reference item was not inhibited by the test item in the toxicity control. The 10 % level (beginning of biodegradation) was reached by the 1st replicate after 12 d, by the 2nd replicate after 6 d. The 2nd replicate reached the pass level of 60 % after 26 d and came to 66 % after 28 d. The 1st replicate came to 56 % after 28 d. The mean biodegradation came to 61 % after 28 d. The validity criteria according to the guideline are fulfilled.Under the test conditions, test material (containing 98 % dicocosalkyl dimethyl ammonium chloride) was considered as readily biodegradable after 28 d (Fiebig S, 2006).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

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