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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:
2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
not applicable
GLP compliance:
yes (incl. certificate)
Test material information:
Composition 1
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
TEST ORGANISMS:
- Type : mixed population of aquatic microorganisms (activated sludge)
- Origin : aeration tank of a wastewater plant treating predominantly domestic sewage (Wupper area water authority, WWTP Odenthal)
- Date of collection : 2016-02-01
- Concentration of inoculum : 30 mg/L suspended solids

PRE-TREATMENT OF THE INOCULUM:
- Before use, the inoculum was stored for one day at room temperature under continuous shaking with aeration
- The sludge was washed twice by adding mineral medium and centrifuging for 10 min at 2000 rpm and 20 °C and decanting off the supernatant
- An aliquot of the wet sludge was dried in order to determine the wet weight / dry weight ratio of the sludge and to prepare a stock suspension (activated sludge) of 3 g dw/L
- The calculated amount of sludge, needed to achieve 300 mL of this stock suspension, was dissolved in mineral medium and then filled up to a defined end volume
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
PRE-TREATMENT OF THE TEST SUBSTANCE:
- 25 mg of the test item were weighed out and filled with 200 mL of mineral medium
- afterwards the volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg test item/L

PRE-TREATMENT OF THE REFERENCE COMPOUND:
- 25 mg of the reference compound were weighed out and filled with 200 mL of mineral medium
- afterwards the volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg reference compound/L

PRE-TREATMENT OF THE TOXICITY CONTROL:
- 25 mg of the test item and 25 mg of the reference compound were weighed out and filled with 200 mL of mineral medium
- afterwards the flask volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg test item and reference compound/L

EXPOSURE CONDITIONS:
- Test volume: 250 mL
- Test apparatus: OxiTopControl System (WTW)
- Number of culture flasks/concentration: 3 (test item), 2 (reference compound), 3 (inoculum blank), 1 (toxicity control)
- Mixing: 1 magnetic stirrer per test vessel
- Test performed in closed vessels: Yes
- Incubation temperature : 22 ± 1 °C
- Test temperature: 22 ± 1°C
- pH: 6.9-7.9 (measured in the test flasks after 28 days)
- pH adjusted: no
- Aeration of dilution water: no
- Continuous darkness: yes

SAMPLING
- Sampling frequency: The BOD (in mg O2/L) was measured daily

CONTROL AND BLANK SYSTEM
- Inoculum blank: Blanks with inoculum and without test item were run in parallel (3 replicates)
Reference substance:
benzoic acid, sodium salt
Remarks:
(Acros Organics) Purity: 99.9 %; Batch-No.: A0357641
Key result
Parameter:
% degradation (O2 consumption)
Value:
11
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
4
Sampling time:
7 d
Parameter:
% degradation (O2 consumption)
Value:
6
Sampling time:
14 d
Parameter:
% degradation (O2 consumption)
Value:
9
Sampling time:
21 d
Details on results:
The toxicity control exhibited degradation rates > 25 % within 14 days.
Results with reference substance:
The reference compound sodium benzoate showed 90 % degradation after 14 days.
Validity criteria fulfilled:
yes
Remarks:
ready biodegradation of reference compound >= 60 % within 14 days; toxicity control exhibited degradation rates > 25 % within 14 days; Replicates difference < 20 %; Oxygen uptake of the inoculum blank was <= 60 mg/L; no pH influence
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Bromhydrin-valerat showed 11 % degradation within 28 days. The reference compound sodium benzoate was degraded to 90% .
Executive summary:

The study was conducted in accordance with the Council Regulation (EC) No 440/2008, Method C.4-D "Manometric Respirometry Test (2008)". This test method is in all essential parts identical with OECD Guideline 301 F (adopted July 1992). A suspension of the test substance in a mineral medium was inoculated and incubated for 28 d under aerobic conditions. During this period, degradation of Bromhydrin-valerat was followed by continuous automated BOD determinations. The 28-day degradation was 11 % while a biodegradation of 90% was observed for the positive control (with reference substance sodium benzoate). In conclusion Bromhydrin-valerat is not readily biodegradable under test conditions.

Description of key information

Bromhydrin-valerat showed 11 % degradation within 28 days.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Bromhydrin-valerat is considered to be "Not Readily Biodegradable".

The reference compound sodium benzoate was degraded to 90% .