Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Qualifier:
according to guideline
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material:test item supplied by sponsor/91112Y
- Expiration date of the lot/batch:12 March 2021
- Purity:92.4%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material:controlled room temperature (15-25℃, ≤70% relative humidity), protected from light and humidity (tight closed container)


Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The secondary effluent was supplied from the sewage plant for domestic sewage in Veszprém county, Hungary.

- Preparation of inoculum for exposure: The secondary effluent used for this study was allowed to settle approximately for an hour, then the decanted effluent was aerated until use (not later than an hour).
Duration of test (contact time):
28 d
Initial conc.:
1.5 mg/L
Based on:
COD
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Solubilising agent (type and concentration if used):deionised water

- Test temperature: The test was carried out in an incubator and controlled environment room (during the formulation and oxygen measuring) at a temperature of 22 ± 2 °C according to guideline.The test flasks were placed into an incubator and kept at 21.3± 22.9°C, in the dark. The temperature was measured on weekdays during the experiment.

- pH: The pH value of the test water was checked prior start of the experiment. The pH of the test water was 7.24.


TEST SYSTEM
- Culturing apparatus: BOD bottles (300 mL) with special neck and glass stoppers.

- Number of culture flasks/concentration:
10 bottles containing the test item and inoculum
10 bottles containing the reference item and inoculum (procedure control)
10 bottles containing only inoculum (inoculum control)
10 bottles containing the test item, reference item and inoculum (toxicity control)

- Method used to create aerobic conditions: The test medium was aerated for 20 minutes and allowed to stand for about 20 hours at the test temperature.

- Measuring equipment:
The oxygen concentrations were measured with an oxygen meter with a stirring O2 electrode. Oxygen measurements were performed in duplicate on days 0, 7, 14, 21 and 28.The COD (chemical oxygen demand) of the test item was determined in the analytical department of the test facility using Lovibond® COD Measuring System.


CONTROL AND BLANK SYSTEM
- Inoculum blank: Only filtered inoculum was added to aqueous test medium.
- Toxicity control: The test Item and the reference item stock solution were mixed into aqueous test medium.


STATISTICAL METHODS:
Reference substance:
benzoic acid, sodium salt
Preliminary study:
The chosen test item concentration was based on the measured chemical oxygen demand (COD): 4.05 ±0.338 mg test item (which is relatively higher than usual)and on the performed 14-d preliminary test.
The concentration of dissolved oxygen resulted a mean of 7.30 mg O2/L after 14 days of incubation in the test item flasks (1a and 1b) in the preliminary test, which resulted a mean of 0.8 % biodegradation within 14 days of the test item, therefore samples for nitrate and nitrite analysis was not taken and measurement of the total oxidised Nitrogen (nitrate and nitrite) concentrations was not performed.
Test performance:
The incubation period of the closed bottle test was 28 days. The oxygen concentrations were measured with an oxygen meter with a stirring O2 electrode. Oxygen measurements were performed in duplicate on days 0, 7, 14, 21 and 28.
Key result
Parameter:
% degradation (O2 consumption)
Value:
14.8
Sampling time:
28 d
Details on results:
In the toxicity control containing both, the test item and the reference item Sodium benzoate, a mean of 35.0 % biodegradation was noted within 14 days and 41.2 % biodegradation after 28 days of incubation.
According to the test guidelines the test item can be assumed to be not inhibitory at the applied concentration level of 1.5 mg/L on the secondary effluent microorganisms because degradation was >25 % within 14 days.
Results with reference substance:
The reference item Sodium benzoate was sufficiently degraded to a mean of 80.0% after 14 days, and to a mean of 91.7 % after 28 days of incubation, based on ThOD, thus confirming the suitability of the used inoculum.

Table:Percentage Biodegradation at Different Time Intervals during the Exposure Period of 28 Days

Day No. % Biodegradation
Test substance Reference substance Toxicity control
7 5.8 74.2 34.0
14 9.9 80.0 35.0
21 9.9 86.7 39.4
28 14.8 91.7 41.2
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Under the test conditions the percentage biodegradation of Test Item reached a mean of 14.8 % after 28 days based on the COD of the test item. According to the test guidelines the pass level for ready biodegradability is removal of 60 % COD/ThOD. Therefore, the test item is considered not readily biodegradable.
Executive summary:

The ready biodegradability was determined in a study in accordance with OECD TG 301D and in compliance with GLP criteria. The test concentration was 1.50 mg/L based on measured chemical oxygen demand (COD). The test medium was inoculated with secondary effluent from  a domestic wastewater treatment plant. The oxygen concentrations were measured  in duplicate on days 0, 7, 14, 21 and 28.Sodium benzoate was used as a reference substance and achieved a mean of 80.0% biodegradation after 14 days confirming the suitability of the inoculum and the test conditions. Complete biodegradation of the test substance (i.e. 100%) was observed at day 10 under the conditions of the test. Under the test conditions the percentage biodegradation of Test Item reached a mean of 14.8 % after 28 days based on the COD of the test item. According to the test guidelines the pass level for ready biodegradability is removal of 60 % COD/ThOD. Therefore, the test item is considered not readily biodegradable.

Description of key information

Biodegradation (%) is 14.8 % after 28 days based on the COD of the test item (OECD301D,GLP).Therefore, the test item is considered not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
not biodegradable
Type of water:
freshwater

Additional information