Oxacycloheptadec-10-en-2-one

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Data is from experimental study report

Qualifier:

according to guideline

Guideline:

OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test)

Version / remarks:

stock solution prepared in water by passive dosing (no solvent).

GLP compliance:

no

Radiolabelling:

no

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Remarks:

Stream of good ecological quality and without known point sources close to sampling point

Details on source and properties of surface water:

- Details on collection (e.g. location, sampling depth, contamination history, procedure): Natural water sampled from Gudenåen (DK) 15th of June 2020. WGS84: 56°6'23.2"N 9°43'17.4"E
- Other details of sample (eg: colour and turbidity): The water was quite clear with a slight light brown hint. Total suspended solids was 2.0 mg/L, total dissolved solids was 210 mg/L.
- Sampling depth: 5-20 cm below surface. No pre-treatment of the natural water.
- Storage conditions: Water kept at 20 ± 1,5°C during transport to lab (4 hours), then stored at 12°C until test setup within 30 hours of sampling.
- Storage length: 30 hrs
- Temperature (°C) at time of collection: 20.0°C.
- pH at time of collection: 6.5
- Biomass (e.g. in mg microbial C/100 mg, CFU or other):
Plate count (24 hours incubation): 36 CFU/mL
Plate count (72 hours incubation): 1300 CFU/mL
- Water filtered: no
- Other: Dissolved non-volatile organic carbon (NVOC) was measured instead of DOC/TOC and was 4.4 mg/L.

Duration of test (contact time):

> 3 - < 7 d

Initial conc.:

0.002 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

TEST CONDITIONS
- Volume of test solution/treatment: 14.5 mL surface water used in each test system, spiked with 0.5 mL stock solution prepared in water by passive dosing.
- Composition of medium: Natural water used as medium
- Test temperature: 12°C
- pH: 6.5
- pH adjusted: no
- Aeration of dilution water: No aeration during test
- Suspended solids concentration: 2.0 mg/l
- Continuous darkness: yes
- Other: Conductivity: 334 µS/cm
- Non volatile dissolved organic carbon in natural water: 4.4 mg/L

TEST SYSTEM
- Culturing apparatus: 20 mL amber headspace vials
- Number of replicates: 15-18 replicate biotic and 15-18 replicate abiotic test systems were used.
- Method used to create aerobic conditions: Aerobic conditions created by using aerobic natural water (initial oxygen content 9.0 mg/L at 20 °C) and incubating using a headspace of 5 mL with a low test substance concentration of 0.002 mg/l.
- Test performed in closed vessels due to significant volatility of test substance: yes, test performed in closed vials.

SAMPLING
- Sampling frequency: At five time-points, three biotic and three abiotic test systems were sacrificed for analysis (day3 and 7).
- Sampling method used per analysis type: Tests systems were put directly on the autosampler of the GCMS without storage.

DESCRIPTION OF CONTROL AND/OR BLANK TREATMENT PREPARATION
CONTROL AND BLANK SYSTEM
Blank test systems were prepared and incubated with biotic and abiotic test systsems and analyzed at each time-point (signal well below the 3% dilution of initial test concentration).
Carryover was < 1.0% and since test systems were analyzed alternating biotic and abiotic test systems this constitutes the detection limit in this test.

STATISTICAL METHODS: Triplicate ratios of biotic/abiotic test system peak areas were calculated for each time point and used in Graph-pad Prism 8.4.3 to fit the first order degradation model with lag phase: Y=IF(x0, Y0=1, K>0

Key result

% Degr.:

> 99

Parameter:

test mat. analysis

Sampling time:

7 d

Remarks on result:

other: primary degradation

Key result

Compartment:

natural water

DT50:

0.6 d

Type:

(pseudo-)first order (= half-life)

Temp.:

12 °C

Remarks on result:

other: Other details not known

Other kinetic parameters:

first order rate constant

Transformation products:

not measured

Evaporation of parent compound:

no

Volatile metabolites:

not specified

Residues:

not specified

Validity criteria fulfilled:

not specified

Conclusions:

Primary biodegradation in surface water from a Danish stream was determined by compound specified analysis and was performed following the modified OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test). The (pseudo-)first order (= half-life) (DT50) of the test chemical was evaluated to be 0.6 days at 12°C. Primary percentage degradation of the test chemical was determined to be >99% at 7 days. Hence, test chemical was considered to be not persistent in surface water.

Executive summary:

Primary biodegradation in surface water from a Danish stream was determined by compound specified analysis. The study was performed following the modified OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test) under aerobic conditions. Natural water (stream of good ecological quality and without known point sources close to sampling point) sampled from Gudenåen (DK) 16th of June 2020. WGS84: 56°6'23.2"N 9°43'17.4"E at a dept of 5 -20 cm below surface was used as a surface water. The water was quite clear with a slight light brown hint. Total suspended solids was 2.0 mg/L, total dissolved solids was 210 mg/L. No pre-treatment was done of the natural water. Water kept at 20 ± 1.5°C during transport to lab (4 hours), then stored at 12°C until test setup within 30 hours of sampling. The temperature and pH at the time of collection of the sample was 20.0°C and 6.5 pH. Biomass i.e., plate count at 24 and 72 hr was 36 CFU/ml and 1281 CFU/ml, respectively. Water was not filtered. Dissolved non-volatile organic carbon (NVOC) was measured instead of DOC/TOC and was 4.4 mg/L. Study was performed using 20 mL amber headspace closed vials. A large no. of biotic test systems (15 -18 replicates) consisting of 14.5 ml surface water and 0.5 ml stock solution was prepared test vials. Stock solution was prepared in water by equilibrium partioning from a pre-loaded silicone rod (passive dosing). This method for preparing stock solutions avoids the need for solvents for spiking. A similar number of abiotic control test systems were prepared using 14.5 ml MilliQ water and 0.5 ml stock solution. Blanks were prepared with 15 ml MilliQ water. Aerobic conditions created by using aerobic natural water (initial oxygen content 9.0 mg/L at 20 °C)  and incubating using a headspace of 5 mL with a low test substance concentration of 0.002 mg/l. Test was conducted at a temperature of 12°C and pH of 6.5 under continuous darkness with conductivity of 334 µS/cm while rolling. pH of the test medium (natural water) was not adjusted. No aeration was provided during the study. Suspended solid concentrations uded in the study was 2.0 mg/l. At 5 -6 time-points, 3 biotic and 3 abiotic test systems were sacrificed for analysis (day 2, 6, 9, 14 and 21). Tests systems were put directly on the autosampler of the GCMS without storage. Blank test systems were prepared and incubated with biotic and abiotic test systems and analyzed at each time-point (signal well below the 3% dilution of initial test concentration). Analysis was carried out using direct immersion solid phase microextraction coupled to GC-MS. Carryover was < 1.0% and since test systems were analyzed alternating biotic and abiotic test systems this constitutes the detection limit in this test. Biodegradation was then evaluated by the ratio between peak areas in the biotic and abiotic test systems. Triplicate ratios of biotic/abiotic test system peak areas were calculated for each time point and used in Graph-pad Prism 8.4.3 to fit the first order degradation model with lag phase. The (pseudo-)first order (= half-life) (DT50) of the test chemical was evaluated to be 0.6 days at 12°C. Primary percentage degradation of the test chemical was determined to be >99% at 7 days. Thus, on the basis of results, test chemical was considered to be not persistent in surface water.

Reference 2

Endpoint:

biodegradation in water: sediment simulation testing

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is readily biodegradable

Description of key information

Primary biodegradation in surface water from a Danish stream was determined by compound specified analysis. The study was performed following the modified OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test) under aerobic conditions. Natural water (stream of good ecological quality and without known point sources close to sampling point) sampled from Gudenåen (DK) 16th of June 2020. WGS84: 56°6'23.2"N 9°43'17.4"E at a dept of 5 -20 cm below surface was used as a surface water. The water was quite clear with a slight light brown hint. Total suspended solids was 2.0 mg/L, total dissolved solids was 210 mg/L. No pre-treatment was done of the natural water. Water kept at 20 ± 1.5°C during transport to lab (4 hours), then stored at 12°C until test setup within 30 hours of sampling. The temperature and pH at the time of collection of the sample was 20.0°C and 6.5 pH. Biomass i.e., plate count at 24 and 72 hr was 36 CFU/ml and 1281 CFU/ml, respectively. Water was not filtered. Dissolved non-volatile organic carbon (NVOC) was measured instead of DOC/TOC and was 4.4 mg/L. Study was performed using 20 mL amber headspace closed vials. A large no. of biotic test systems (15 -18 replicates) consisting of 14.5 ml surface water and 0.5 ml stock solution was prepared test vials. Stock solution was prepared in water by equilibrium partioning from a pre-loaded silicone rod (passive dosing). This method for preparing stock solutions avoids the need for solvents for spiking. A similar number of abiotic control test systems were prepared using 14.5 ml MilliQ water and 0.5 ml stock solution. Blanks were prepared with 15 ml MilliQ water. Aerobic conditions created by using aerobic natural water (initial oxygen content 9.0 mg/L at 20 °C)  and incubating using a headspace of 5 mL with a low test substance concentration of 0.002 mg/l. Test was conducted at a temperature of 12°C and pH of 6.5 under continuous darkness with conductivity of 334 µS/cm while rolling. pH of the test medium (natural water) was not adjusted. No aeration was provided during the study. Suspended solid concentrations uded in the study was 2.0 mg/l. At 5 -6 time-points, 3 biotic and 3 abiotic test systems were sacrificed for analysis (day 2, 6, 9, 14 and 21). Tests systems were put directly on the autosampler of the GCMS without storage. Blank test systems were prepared and incubated with biotic and abiotic test systems and analyzed at each time-point (signal well below the 3% dilution of initial test concentration). Analysis was carried out using direct immersion solid phase microextraction coupled to GC-MS. Carryover was < 1.0% and since test systems were analyzed alternating biotic and abiotic test systems this constitutes the detection limit in this test. Biodegradation was then evaluated by the ratio between peak areas in the biotic and abiotic test systems. Triplicate ratios of biotic/abiotic test system peak areas were calculated for each time point and used in Graph-pad Prism 8.4.3 to fit the first order degradation model with lag phase. The (pseudo-)first order (= half-life) (DT50) of the test chemical was evaluated to be 0.6 days at 12°C. Primary percentage degradation of the test chemical was determined to be >99% at 7 days. Thus, on the basis of results, test chemical was considered to be not persistent in surface water.

In accordance with column 2 of Annex IX of the REACH regulation, testing for this end point is scientifically not necessary and does not need to be conducted since the test chemical is readily biodegradable in water.

Key value for chemical safety assessment

Half-life in freshwater:

0.6 d

at the temperature of:

12 °C

Additional information

Primary biodegradation in surface water from a Danish stream was determined by compound specified analysis. The study was performed following the modified OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test) under aerobic conditions. Natural water (stream of good ecological quality and without known point sources close to sampling point) sampled from Gudenåen (DK) 16th of June 2020. WGS84: 56°6'23.2"N 9°43'17.4"E at a dept of 5 -20 cm below surface was used as a surface water. The water was quite clear with a slight light brown hint. Total suspended solids was 2.0 mg/L, total dissolved solids was 210 mg/L. No pre-treatment was done of the natural water. Water kept at 20 ± 1.5°C during transport to lab (4 hours), then stored at 12°C until test setup within 30 hours of sampling. The temperature and pH at the time of collection of the sample was 20.0°C and 6.5 pH. Biomass i.e., plate count at 24 and 72 hr was 36 CFU/ml and 1281 CFU/ml, respectively. Water was not filtered. Dissolved non-volatile organic carbon (NVOC) was measured instead of DOC/TOC and was 4.4 mg/L. Study was performed using 20 mL amber headspace closed vials. A large no. of biotic test systems (15 -18 replicates) consisting of 14.5 ml surface water and 0.5 ml stock solution was prepared test vials. Stock solution was prepared in water by equilibrium partioning from a pre-loaded silicone rod (passive dosing). This method for preparing stock solutions avoids the need for solvents for spiking. A similar number of abiotic control test systems were prepared using 14.5 ml MilliQ water and 0.5 ml stock solution. Blanks were prepared with 15 ml MilliQ water. Aerobic conditions created by using aerobic natural water (initial oxygen content 9.0 mg/L at 20 °C)  and incubating using a headspace of 5 mL with a low test substance concentration of 0.002 mg/l. Test was conducted at a temperature of 12°C and pH of 6.5 under continuous darkness with conductivity of 334 µS/cm while rolling. pH of the test medium (natural water) was not adjusted. No aeration was provided during the study. Suspended solid concentrations uded in the study was 2.0 mg/l. At 5 -6 time-points, 3 biotic and 3 abiotic test systems were sacrificed for analysis (day 2, 6, 9, 14 and 21). Tests systems were put directly on the autosampler of the GCMS without storage. Blank test systems were prepared and incubated with biotic and abiotic test systems and analyzed at each time-point (signal well below the 3% dilution of initial test concentration). Analysis was carried out using direct immersion solid phase microextraction coupled to GC-MS. Carryover was < 1.0% and since test systems were analyzed alternating biotic and abiotic test systems this constitutes the detection limit in this test. Biodegradation was then evaluated by the ratio between peak areas in the biotic and abiotic test systems. Triplicate ratios of biotic/abiotic test system peak areas were calculated for each time point and used in Graph-pad Prism 8.4.3 to fit the first order degradation model with lag phase. The (pseudo-)first order (= half-life) (DT50) of the test chemical was evaluated to be 0.6 days at 12°C. Primary percentage degradation of the test chemical was determined to be >99% at 7 days. Thus, on the basis of results, test chemical was considered to be not persistent in surface water.

In accordance with column 2 of Annex IX of the REACH regulation, testing for this end point is scientifically not necessary and does not need to be conducted since the test chemical is readily biodegradable in water.