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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: screening test, other
Type of information:
experimental study
Adequacy of study:
key study
Study period:
19 January 2019 (Study Initiation to 16 May 2019 (Experimental Completion)
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Remarks:
The test guidelines were suggested test solution concentration would be 2 to 5 mg/L, but considering low water solubility of the test item, study was performed at the maximum solubility which can be achieved for the test item.
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
yes
Remarks:
The test guidelines were suggested test solution concentration would be 2 to 5 mg/L, but considering low water solubility of the test item, study was performed at the maximum solubility which can be achieved for the test item.
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source of test material: Nitika Pharmaceutical Specialities Pvt. Ltd.
- Lot/batch No.of test material: IRST7H780L
- Expiration date of the lot/batch: August 2023
- Purity test (release) date: September 2018

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature (ambient), in original container as supplied by the Sponsor.
- Stability under test conditions: Assumed stable for the duration of the study
- Solubility and stability of the test substance in the solvent/vehicle: The test item (as supplied, and taking purity into account) was transferred into a 10 mL volumetric flask, dissolved in 7 mL of 1% IGEPAL solution and sonicated for 5 minutes. The volume was made up with 1% IGEPAL solution [stock solution 132.93 mg/L]. . Final concentration of test item in mineral medium was 0.13 mg/L. The test guidelines state a test solution concentration of 2 to 5 mg/L, but considering low water solubility of the test item, the study was performed at the maximum acheivable solubility for the test item.
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: None

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing:
Stock Solution of Test Item: A weight of 20.45 mg test item (as supplied, and taking purity into account) was transferred into a 10 mL volumetric flask, dissolved in 7 mL of 1% IGEPAL solution and sonicated for 5 minutes. The volume was made up with 1% IGEPAL solution [stock solution 132.93 mg/L, TI].
Bulk Solution of Test Item: The test suspension was prepared by adding 4.0 mL of test item stock solution (TI) and 4.0 mL of inoculum to 3992 mL of mineral medium in a 5 L conical flask. The solution was mixed thoroughly. The final concentration of test item in mineral medium was 0.13 mg/L.

OTHER SPECIFICS:
- measurement of pH, osmolality, and precipitate in the culture medium to which the test chemical is added: Stock solution pH recorded, osmolality and presence of any precipitate not specified.
Oxygen conditions:
anaerobic
Inoculum or test system:
sewage, domestic, adapted
Details on inoculum:
- Source of inoculum/activated sludge: Secondary effluent from the JRF Sewage Treatment Plant treating predominantly domestic sewage was used as the inoculum.
- Laboratory culture: Yes
- Method of cultivation: Incubation was performed under dark conditions at 22 ± 2°C.
- Storage conditions: Not specified
- Storage length: Not specified
- Preparation of inoculum for exposure: Secondary effluent from the JRF Sewage Treatment Plant treating predominantly domestic sewage was used as the inoculum. The Secondary effluent was filtered through a Whatman No. 1 filter paper. The inoculum was pre-conditioned by aerating at 22 ± 2 °C for 6 days. The inoculum was analysed for microorganism concentration and confirmed as 1 x 105 CFU/mL.
- Pretreatment: The inoculum was pre-conditioned by aerating at 22 ± 2 °C for 6 days.
- Concentration of sludge: 1 x 105 CFU/mL.
- Initial cell/biomass concentration: Not specified
- Water filtered: yes
- Type and size of filter used, if any: The Secondary effluent was filtered through a Whatman No. 1 filter paper.
Duration of test (contact time):
28 d
Initial conc.:
0.13 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium: prepared in Milli-Q water (g/100 ml)
Stock Solutions Chemicals used Quantity (g) Final volume (mL)
A Potassium dihydrogen orthophosphate 0.850 100
Dipotassium hydrogen orthophosphate 2.175
Disodium hydrogen orthophosphate dihydrate 3.340
Ammonium chloride 0.050
B Calcium chloride dihydrate 3.640 100
C Magnesium sulphate heptahydrate 2.250 100
D Iron (III) chloride hexahydrate 0.0250 100

- Additional substrate: no
- Solubilising agent (type and concentration if used): IGEPAL (1% solution) used as the solubilizing agent to meet the criteria for the blank control
- Test temperature: 22 ± 2°C, under dark conditions
- pH: 7.43
- pH adjusted: no
- Aeration of dilution water: yes, the mineral medium was strongly aerated for 20 minutes and allowed to stand for 20 h at 22 ± °C. All operations were performed in a horizontal laminar flow under aseptic conditions.
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 5L conical flasks
- Number of culture flasks/concentration: 2.
- Method used to create aerobic conditions: The inoculum was pre-conditioned by aerating at 22 ± 2 °C for 6 days
- Measuring equipment: Dissolved Oxygen meter
- Test performed in closed vessels due to significant volatility of test substance: no, test item not volatile
- Test performed in open system: no,closed bottle test used in accordance with OECD 301D

SAMPLING
- Sampling frequency: 0, 7, 14, 21 and 28 days
- Sampling method: Dissolved Oxygen (DO) Meter used to determine DO concetration in flasks at timepoints of 0, 7, 14, 21 and 28 days
- Sample storage before analysis: n/a

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, the inoculum blank was prepared by mixing 4.0 mL inoculum with 3996 mL of mineral medium in a conical flask of 5 L capacity. The solution was mixed thoroughly.
- Abiotic sterile control: no
- Toxicity control: yes, the toxicity control was prepared by mixing 2.0 mL stock solution of Sodium benzoate, 2.0 mL stock solution of test item and 2.0 mL of inoculum to 1994 mL of mineral medium in a conical flask of 2 L capacity. The solution was mixed thoroughly. The final concentration was 2.10 mg/L of reference substance and 0.13 mg/L of test item in mineral medium.

STATISTICAL METHODS: n/a
Reference substance:
benzoic acid, sodium salt
Preliminary study:
No
Key result
Parameter:
% degradation (DOC removal)
Value:
552.68
Sampling time:
28 d
Parameter:
% degradation (DOC removal)
Value:
468.07
Sampling time:
21 d
Parameter:
% degradation (DOC removal)
Value:
369.39
Sampling time:
14 d
Parameter:
% degradation (DOC removal)
Value:
290.43
Sampling time:
7 d
Results with reference substance:
The percent degradation of the reference substance (Sodium benzoate) on days 7, 14, 21, and 28 was 76.89, 78.63, 84.03, and 98.02 %, respectively.

Treatment % Degradation (Based on ThOD)
7 14 21 28
Procedure Control 76.89 78.63 84.03 98.02
Test Solution 290.43 369.39 468.07 552.68
Toxicity Control 153.64 171.28 - -
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test item was readily biodegradable and not toxic to microorganisms in the inoculum.

Description of key information

Based on the results of this test, the test item was readily biodegradable and not toxic to microorganisms in the inoculum.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information