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Environmental fate & pathways

Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
The test was inoculated with effluent of the sewage treatment plant Hochdahl (1 mL/L). The effluent from the sewage treatment plant predominantly treating domestic sewage was filtered through a coarse paper filter, the first 200 mL being discarded.
Duration of test (contact time):
28 d
Initial conc.:
10 mg/L
Based on:
DOC
Initial conc.:
5 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
Stock solutions (i.e. 1000 mg/L) of the test substance and reference were prepared and calculated aliquots were added to the final test solutions. The final concentration of test substance was => 5 respectively 10 mg/L DOC. The final concentration of the reference was => 10 mg/L DOC.
Reference substance:
other: sodium benzoate
Key result
Parameter:
% degradation (DOC removal)
Value:
98
Sampling time:
28 d
Details on results:
Results are tabulated in 'Any other information on results incl. tables'.
Results with reference substance:
Results of the reference substance are tabulaten in 'Any other information on results incl. tables'

Table: DOC removal of test substance

Day

% DOC removal 5 mg DOC

% DOC removal 10 mg DOC

7

55

51

14

98

98

21

95

98

28

95

98

 

Table: Reference (soodium benzoate)

Day

% DOC removal

7

96

14

98

21

100

28

98

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2007-01-24 to 2001-03-07
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
equivalent or similar to guideline
Guideline:
other: DIN 38414 part 8
Deviations:
yes
Principles of method if other than guideline:
a defined amount of test substance was added to the inoculum. The biodegradability was measured by comparing the inoculum control with the inoculum containing the test substance.
GLP compliance:
no
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Name of test item (as cited by study report): Sodium-N-lauryl-ß-iminodipropionate, Deriphat 160 C
- Physical state: Yellowish liquid
- Analytical purity: 30% active substance
- Lot/batch No.: S65250007
- Expiration date of the lot/batch: 2007-09-01

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature
Oxygen conditions:
anaerobic
Inoculum or test system:
anaerobic sludge
Details on inoculum:
- Source of inoculum/activated sludge: STP Düsseldorf, Germany
- Method of cultivation: Predominantly digested sludge (89%, approx. 27 days of age) mixed with activated aerobic sludge (11%)
Duration of test (contact time):
41 d
Initial conc.:
2 g/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
other: digester gas evolution (CH4 and CO2)
Details on study design:
TEST CONDITIONS
- Test temperature: 35 ± 1°C
- pH: 7.3 to 7.6

TEST SYSTEM
- Number of culture flasks/concentration: 2

SAMPLING
- Sampling frequency: Daily

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2




Parameter:
other: digester gas evolution (CH4 and CO2)
Value:
0
Sampling time:
41 d
Interpretation of results:
under test conditions no biodegradation observed

Description of key information

Readily biodegradable (according to OECD criteria).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The biodegradation potential of the substance in water was determined in a non-GLP screening study according to OECD TG 301 E (DOC Removal Test) (Henkel KGaA, 2006). In this study 5 and 10 mg/L test substance (expressed as DOC) was inoculated with non-adapted activated sludge from a domestic sewage treatment plant for 28 days under aerobic conditions in the dark. After the 28-day incubation period the substance was biodegraded almost completely (98%). The 10-day window criterion was met. Based on these findings, the substance is classified as readily biodegradable.

As supporting information, the biodegradation potential of the test substance in water under anaerobic conditions was determined in a non-GLP study according to DIN 38414-8 (Chemisch-biologische Laboratorien, 2007). In this study, 2 g/L test substance was inoculated with anaerobic sludge (predominantly digested sludge mixed with activated aerobic sludge) for 41 days. Digester gas evolution (CH4 and CO2) was measured daily as a parameter for biodegradation estimation. After the 41 -day incubation period, no biodegradation was observed (0%). Therefore, the substance was classified as not biodegradable under anaerobic test conditions.