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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Reference
Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September 2019 - March 2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test)
Deviations:
no
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: Eurofins EAG, Columbia MO on July 26, 2019, lot number 88676-1-5-1
- Expiration date of the lot/batch: no
- Purity test date:

RADIOLABELLING INFORMATION (if applicable)
- Radiochemical purity: radiochemical purity was 100%, and the A total of 0.5 mCi was supplied,
- Specific activity: specific activity was 164 µCi/mg.
- Locations of the label: on aliphatic carbon
- Expiration date of radiochemical substance: not stated

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: The test substance was stored in a freezer.
Radiolabelling:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
natural water: freshwater
Details on source and properties of surface water:
- Details on collection (e.g. location, sampling depth, contamination history, procedure):The water used in this study was collected from Tuckahoe Lake, Queen Anne MD on September 16, 2019. The test system was selected to be consistent with study guidelines. The water was collected from the surface (air:water interface). The water was clear, with visibility to 4 feet (i.e., low turbidity).
- Storage conditions: The water was stored refrigerated prior to dispensing for use.
- Storage length:
- Temperature (°C) at time of collection: 24.5 °C
- pH at time of collection:7.31
- Electrical conductivity: NA
- Redox potential (mv) initial/final: NA
- Oxygen concentration (mg/l) initial/final:dissolved oxygen (DO) level was 8.70 mg/L
- Hardness (CaCO3):NA
- Dissolved organic carbon (%): 2.4 ppm
- Biomass (e.g. in mg microbial C/100 mg, CFU or other):2.4 × 10^3 CFU/mL
- Water filtered: yes
- Type and size of filter used, if any:100 µm nylon filter


Duration of test (contact time):
60 d
Initial conc.:
10 µg/L
Based on:
test mat.
Initial conc.:
100 µg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
radiochem. meas.
test mat. analysis
Details on study design:
TEST CONDITIONS
- Volume of test solution/treatment: 50 mL
- Composition of medium:
Total Nitrogen: 3.1 ppm
Ammonium Nitrogen: 1.0 ppm
Nitrate: 2.7 ppm
Nitrite: <0.1 ppm
Total Phosphorus: 0.1 ppm
Dissolved orthophosphate: 0.1 ppm
Total organic carbon: 2.6 ppm
Dissolved organic carbon: 2.4 ppm
Biological Oxygen Demand: 1.1 ppm

- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Test temperature: 11.4 to 12.1 OC
- pH: 7.31
- pH adjusted: no
- CEC (meq/100 g):
- Aeration of dilution water:
- Suspended solids concentration: 15 mg/L
- Continuous darkness: yes
- Any indication of the test material adsorbing to the walls of the test apparatus: no
- Other:

TEST SYSTEM
- Culturing apparatus: test vessels were glass serum bottles of approximately 156 mL volume sealed with silicone/PTFE septa and crimp caps.
- Number of culture flasks/concentration: 16 for 10 microgram/L, 16 for 100microgram/L
- Method used to create aerobic conditions: Aerobic conditions were monitored by dissolved oxygen measurements in control vessels.
- Method used to create anaerobic conditions:
- Method used to control oxygen conditions:
- Measuring equipment:

- Test performed in closed vessels due to significant volatility of test substance: to collect co2 gas
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: At each sampling interval, vessels selected for analysis were attached to an air flow-through system designed to purge vessel headspace with air, and collect 14C volatile gases and 14CO2. Effluent gases were passed through ethylene glycol to trap organic volatiles, followed by an alkali solution to trap evolved carbon dioxide.
- Other:

SAMPLING
- Sampling frequency: Days 7, 14, 28, 42, and 60.
- Sampling method used per analysis type: Following removal from incubation, vessels were connected to an air flow-through system designed to purge the vessel headspace and trap 14CO2 and 14C volatile gases. The vessels’ septa were pierced with hypodermic needles in two places to provide intake and outflow ports. The intake port was open to room air via connection to a flowmeter in order to monitor airflow. The outflow port was connected to a series of gas trapping vials. Effluent from each test vessel was drawn through the trapping vials via a vacuum source. The trapping train consisted of four 40-mL vials. The first vial was empty to act as a security trap. The second vial contained 25 mL of ethylene glycol (EG) to trap 14C volatile gases. The third vial was empty to act as another security trap, and the fourth vial contained 25 mL of 1.5 M potassium hydroxide (KOH) to trap 14CO2. The KOH trap was connected to a vacuum manifold to draw air through the test vessel and traps. The vacuum manifold was equipped with individual valves for each test vessel. Connections were made with tygon and teflon tubing. Sterile syringe filters (Whatman 0.2 µm) were attached to the intake line of each of the sterilized vessels during purging. Air flow was typically set to maintain a flow rate of approximately 17 mL/min. to produce slow, steady bubbling in the trap vials. Vessel headspaces were purged with at least 5 headspace-volumes of air. Three replicate 1-mL aliquots of each EG and KOH trap were taken for LSC analysis.
- Sterility check if applicable:
- Sample storage before analysis: no
- Other:

DESCRIPTION OF CONTROL AND/OR BLANK TREATMENT PREPARATION
CONTROL AND BLANK SYSTEM
- Inoculum blank: 7 flasks
- Abiotic sterile control: 8 flasks for 100 microgram/L
- Toxicity control:
- Other: solvent control: 7 flasks

STATISTICAL METHODS:The disappearance rates of parent FR-513 from the test systems and formation rates of 14C gases (mineralization) were not sufficient for statistical evaluation and were not modeled.
Reference substance:
benzoic acid, sodium salt
Key result
Compartment:
natural water: freshwater
DT50:
> 60 d
Type:
(pseudo-)first order (= half-life)
Temp.:
12 °C
Mineralization rate (in CO2):
0 d-1
Transformation products:
no
Remarks:
Not in all of the flasks minor peaks in HPLC chromatograms appers
Evaporation of parent compound:
no
Volatile metabolites:
no
Residues:
no
Details on results:
TEST CONDITIONS
- Aerobicity (or anaerobicity), moisture, temperature and other experimental conditions maintained throughout the study: Yes
- Anomalies or problems encountered (if yes): no

TRANSFORMATION PRODUCTS
Two sections in HPLC chromatogram were detected for transformation products. Reagion of interest 1 and 3. These areas were identifiy in some of the flsks and were below 10% . all efforts to identify reagion of interest 3 were failed.

TOTAL UNIDENTIFIED RADIOACTIVITY (RANGE) OF APPLIED AMOUNT:

EXTRACTABLE RESIDUES
- % of applied amount at day 0:
- % of applied amount at end of study period:

NON-EXTRACTABLE RESIDUES
- % of applied amount at day 0:
- % of applied amount at end of study period:

MINERALISATION
- % of applied radioactivity present as CO2 at end of study:0

VOLATILIZATION
- % of the applied radioactivity present as volatile organics at end of study:0

STERILE TREATMENTS (if used)
- Transformation of the parent compound:no
- Formation of transformation products:no
- Formation of extractable and non-extractable residues:no
- Volatilization:no

Validity criteria fulfilled:
yes
Conclusions:
Parent FR-513 remained intact in the Tuckahoe Lake water test system in this study. The DT50 and DT90 are both reported as >60 days, the duration of the study.
14C gas production was insufficient to determine a rate of mineralization, and the T50 for ultimate degradation is reported as >60 days, the duration of the study.
Data from sterile vessels indicated that no degradation took place in the absence of biological activity.
A standard plate count verified microbial presence, and mineralization data from reference vessels indicated that the microbial population was viable and active over the course of the study.

Executive summary:

Parent FR-513 remained intact in the Tuckahoe Lake water test system in this study. The DT50and DT90are both reported as >60 days, the duration of the study.

 


Description of key information

Key value for chemical safety assessment

Half-life in freshwater:
60 d
at the temperature of:
12 °C

Additional information