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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
Study period:
27 Nov. 1996-25 Dec. 1996
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-B (Determination of the "Ready" Biodegradability - Modified OECD Screening Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Severn Trent Water Plc sewage treatment plant at Belper, Derbyshire, UK
- Preparation of inoculum for exposure: The effluent sample was filtered through Postlip filter paper (approximately first 200 ml discarded) and the filtrate maintained on continuous aeration at 21 C prior to use.
Duration of test (contact time):
28 d
Initial conc.:
113 mg/L
Based on:
test mat.
Initial conc.:
40 mg/L
Based on:
other: TOD
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium: see below
- Solubilising agent (type and concentration if used): no
- Test temperature: 25 +/- 2 C
- pH: 7.4
- pH adjusted: yes on sampling days
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 3 litre glass culture vessel
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: The culture vessels were covered with polypropylene top to reduce evaporation and constantly aerated with compressed air via a narrow bore glass tube.
- Other: Eachculture vessel was also stirred constantly by magnetic stirrers.

SAMPLING
- Sampling frequency: at 0 hrs and on days 1,2,3,6,8,10, 14,16, 21,23,27 and 28.
- Sampling method: Approximately 20 ml were withdrawn by plastic disposable syringe and filtered through 0.45 um Gelman Acrocap disposable filters. The approximate 5 ml of filtrate was discarded.
- Other: Prior to sampling for analysis any losss due to evaporation were corrected by the addition of deionised water and any material adhering to the culture vessel resuspended.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, in duplicate
- Abiotic sterile control: no
- Toxicity control: The toxicity control was motted from this test as the results of an acute tocicity to bacteria (Safepharm Laboratories project no. 988/002) showed that there to be no toxic effects to bacteria at a concentration of 10000 mg/L.
- Other: Each vessel was inoculated with sewage treatment micro-organisms at a rate of 0.5 ml/L

Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (DOC removal)
Value:
11
Sampling time:
28 d
Results with reference substance:
The standard material, sodium benzoate, attained 98% degradation after 28 days, thereby confirming the suitability of the inoculum and culture conditions.
Validity criteria fulfilled:
yes
Remarks:
the standard material attained more than 70% degradation within 14 days.
Interpretation of results:
other: not readily biodegradable
Conclusions:
The substance or its degradation products attained 11% degradation after 28 days and therefore cannot be considered as readily biodegradable under conditions of OECD 301E. As no abiotic control was established in the study a clear identification of degradation processes is not possible. However, the observations show clear indication that degradation products of AAPH are also not readily biodegradable.
Endpoint:
biodegradation in water: screening test, other
Type of information:
experimental study
Adequacy of study:
key study
Study period:
30.11.16-28.04.17
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
yes
Remarks:
uncritial deviation in temperature (lower)
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Remarks:
adaptation unlikely
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf.
Date of collection: 09. Dec. 2016, batch no: 20161209
- Laboratory culture:
- Method of cultivation:
- Storage conditions:
- Storage length:
- Preparation of inoculum for exposure:
- Pretreatment: filtered, double washed (tapwater), re-suspended in test medium, aerated
- Concentration of sludge: 4160 mg (dw) suspended solids/L
- Initial cell/biomass concentration:
- Water filtered: yes/no
- Type and size of filter used, if any:
Duration of test (contact time):
28 d
Initial conc.:
55.6 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: freshly prepared standard medium acc. guideline
- Additional substrate:
- Solubilising agent (type and concentration if used):
- Test temperature: 18.7 - 21.7 °C
- pH: blanks: 7.3, positive control 7.1, test item 7.0, abiotic contr. 6.5, tox contr 6.8
- pH adjusted: no
- CEC (meq/100 g):
- Aeration of dilution water:
- Suspended solids concentration: see above
- Continuous darkness: not stated
- Other:

TEST SYSTEM
- Culturing apparatus: 2000 mL flasks
- Number of culture flasks/concentration: 2, 20 mg organic carbon/L (nom), 56.0 mg/L test item
- Method used to create aerobic conditions: aeration with purified (act. charcoal), CO2-scrubbed, moisteded air, Ba(OH)2 control
- Method used to create anaerobic conditions: -
- Measuring equipment: carbon analyser TOC multi N/C 2100S, Analytik Jena (at least duplicate measurement)
- Test performed in closed vessels due to significant volatility of test substance: no
- Test performed in open system: -
- Details of trap for CO2 and volatile organics if used: 100 mL 0.25 M NaOH solution
- Other:

SAMPLING
- Sampling frequency: on day 0, 2,4,7,9,11,15,17,23,29
- Sampling method: 1 mL samples were taken from scrubber flasks, on day 28 test flasks were acidified (5 mL 2M HCl)
- Sterility check if applicable:
- Sample storage before analysis:
- Other:

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes
- Toxicity control: yes
- Other:

STATISTICAL METHODS:
Reference substance:
aniline
Key result
Parameter:
% degradation (CO2 evolution)
Value:
ca. 20.8
St. dev.:
0.2
Sampling time:
28 d
Results with reference substance:
89.7 (± 3.5) % after 28 days
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Only about 20 % degradation of the test item was observed under test conditions failing the defined criteria for readily biodegradation. Degradation missed 60 % within 28 days, though. Therefore, the test item is considered as “not ultimately biodegradable within 28 days”, too.
However, at the end of the test no plateau of degradation was reached yet, indicating further biodegradation is possible.

Description of key information

Biodegradation of 2,2'-azobis(2 -methylpropionamidine) dihydrochloride and its degradation products were examined in two screening tests for readily biodegradability indicating a low rate of biodegradation under test conditions.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information