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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:
from 2010-01 to 2010-03
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
Institut für Biologische Analytik und Consulting IBACON GmbH, Arheilger Weg 17, 64380 Rossdorf, Germany
Specific details on test material used for the study:
MCPP-P Acid
Purity: 91.7%
Batch: 20043
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Aerobic activated sludge, microorganisms from a domestic waste water treatment plant was supplied by the sewage plant in Darmstadt, Germany.
The activated sludge was washed by centrifugation. The solid material was re-suspended in tap water and centrifuged again. The procedure was repeated three times. The sediment was re-suspended in test water and aerated to two days. The ratio wet to dry weight sludge was determined. Corresponding to this rate 1.5 g dry material per liter was mixed with test water and used for the experiment.
Duration of test (contact time):
28 d
Initial conc.:
83 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Test water: standard OECD medium
- Solubilising agent: no
- Test temperature: 22+- 1 °C
- Suspended solids concentration: 1.5 g dry material per liter
- pH: start: 7.5-7.6; end: 6.8-7.4
- pH adjustment: no
- Continuous darkness: yes
- Other: climatised room

TEST SYSTEM
- Culturing apparatus:
- Number of culture flasks/concentration: 2

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 replicates, 5 mL activated sludge
- Abiotic sterile control: yes, one; 20.5 mg test item + 5 mL HgCl2
- Toxicity control: yes, one; 20.0 mg test item + 20.2 mg reference item + 5 mL activated sludge
- Other:

STATISTICAL METHODS:
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
85
Sampling time:
28 d
Details on results:
In the toxicity control containing both the test item and the reference item, 75 % biodegradation was noted within 14 days and 83 % biodegradation after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms.
Key result
Parameter:
COD
Value:
1.64 g O2/g test mat.
Results with reference substance:
The reference compound sodium benzoate showed 76 % degradation after 7 days and 87 % degradation after 14 days.

MCPP-P acid contains no nitrogen, therefore, the evaluation of biodegradation had to be based on THOD(NH4).

The 10-d window was passed from day 8 to day 18.

Validity criteria fulfilled:
yes
Remarks:
(The percent degradation of the reference compound sodium benzoate reached the level of >= 40 % after 7 days and >= 65 % after 14 days.)
Interpretation of results:
readily biodegradable
Conclusions:
For MCPP-P acid the 28-day degradation was 85 % and for the positive control (with reference substance benzoic acid, sodium salt) the biodegradation was 87 % after 14 days. In conclusion, MCPP-P acid is considered to be "Readily Biodegradable".
Executive summary:

Biodegradation in water was investigated with MCPP-P acid (read-across). MCPP-P acid is the main hydrolysis product of MCPP-P 2-EHE.

 

To test for its ready biodegradability potential, MCPP-P acid was incubated for 28 days in continuously stirred 250 mL closed flask in the dark with an inoculum of mixed population of aquatic microorganisms (activated sludge) from domestic wastewater treatment plants. In this assay, biodegradation was estimated by biological oxygen demand (BOD) over time. BOD was determined daily measuring the drop in pressure in the automated respirometer flasks. The incubation temperature was 22 ± 1 °C, pH was 7.5 – 7.6. The concentration of inoculum was 30 mg/L and the concentration of the test substance was 1.5 g/L. For MCPP-P acid the 28-day degradation was 85 % and for the positive control (with reference substance benzoic acid, sodium salt) the biodegradation was 87 % after 14 days. In conclusion MCPP-P acid is considered to be "Readily Biodegradable".

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Please refer to section 13 for "Read Across justification".
Reason / purpose for cross-reference:
read-across source
Key result
Parameter:
% degradation (O2 consumption)
Value:
85
Sampling time:
28 d
Key result
Parameter:
COD
Value:
1.64 g O2/g test mat.

Description of key information

For MCPP-P acid the 28-day degradation was 85 % and for the positive control (with reference substance benzoic acid, sodium salt) the biodegradation was 87 % after 14 days. In conclusion, MCPP-P acid is considered to be "Readily Biodegradable".

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Biodegradation in water was investigated with MCPP-P acid as this acid is the major hydrolysis product of MCPP-P 2-EHE (read-across).

To test for its ready biodegradability potential, MCPP-P acid was incubated for 28 days in continuously stirred 250 mL closed flask in the dark with an inoculum of mixed population of aquatic microorganisms (activated sludge) from domestic wastewater treatment plants. In this assay, biodegradation was estimated by biological oxygen demand (BOD) over time. BOD was determined daily measuring the drop in pressure in the automated respirometer flasks. The incubation temperature was 22 ± 1 °C, pH was 7.5 – 7.6. The concentration of inoculum was 30 mg/L and the concentration of the test substance was 1.5 g/L. For MCPP-P acid the 28-day degradation was 85 % and for the positive control (with reference substance benzoic acid, sodium salt) the biodegradation was 87 % after 14 days. In conclusion MCPP-P acid is considered to be "Readily Biodegradable".