Methyl (R)-2-(4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy)propionate

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: sediment simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

other: Biologische Bundesanstalt Guidelines, Part IV, Section 5-1

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EC Directive 91/414/EEC

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

(Pyridine-4,5-14C) DE-535 methyl ester
Lot #: GHD-1352-31a, sub-sample INV 89/36
Radiochemical purity: 89.3%
Radioactivity: 13.3 µCi
Specific activity: 70.1 µCi/mg (26.5 mCi/mmole)


(Phenyl-(UL)-14C) DE-535 methyl ester
Lot #: GHD-1284-99a, sub-sample INV 89/31
Radiochemical purity: 99+%
Radioactivity: 4.7 µCi
Specific activity: 46.3 µCi/mg (17.5 mCi/mmole)

Radiolabelling:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water / sediment: freshwater

Details on source and properties of surface water:

- Details on collection: Institute of Freshwater Ecology (lFE) , River Laboratory, Wareham, Dorset
- Mean water depth above sediment (cm): 13.8 ± 0.8 (Mill stream pond) and 14.3 ± 3.4 (Iron hatch run-off)
- Storage conditions: 3 to 7.5°C
- Water temperature just below surface (°C): 10.5 ± 0.2 (Mill stream pond) and 10.5 ± 0.3 (Iron hatch run-off)
- Water temperature 5 ern above sediment (°C): 10.2 ± 0.2 (Mill stream pond) and 10.1 ± 0.1 (Iron hatch run-off)
- pH: 7.74 ± 0.05 (Mill stream pond) and 8.12 ± 0.02 (Iron hatch run-off)
- Redox potential (mv): +310 (Mill stream pond) and +270 (Iron hatch run-off)
- Oxygen concentration 5 cm above the sediment (%): 98.3 (Mill stream pond) ± 1.5 and 99.0 ± 1.0 (Iron hatch run-off)
- Hardness (mg/L as CaCO3): 274.14 (Mill stream pond) and 342.41 (Iron hatch run-off)
- Dissolved organic carbon (%): 7.1 (Mill stream pond) and 0.3 (Iron hatch run-off)
- Biomass (e.g. in mg microbial C/100 mg, CFU or other):

Details on source and properties of sediment:

- Details on collection: Institute of Freshwater Ecology (lFE) , River Laboratory, Wareham, Dorset
- Storage conditions: 3 to 7.5°C
- Textural classification (i.e. %sand/silt/clay): 0/70.1/30.0 (Mill stream pond) and 24.3/73.8/1.9 (Iron hatch run-off)
- pH (I :2.5) extract in water: 7.6 (Mill stream pond) and 7.9 (Iron hatch run-off)
- pH (1 :2.5) extract in 1M KCI: 7.3 (Mill stream pond) and 7.9 (Iron hatch run-off)
- Organic carbon (%): 7.1 (Mill stream pond) and 0.3 (Iron hatch run-off)
- Biomass (µg /g soil): 1208.35 (Mill stream pond) and 347.21 (Iron hatch run-off)
- Cation exchange capacity (CEC) (mEq/100 g): 44.7 (Mill stream pond) and 0.2 (Iron hatch run-off)
- Total nitrogen (%): 0.79 (Mill stream pond) and 0.02 (Iron hatch run-off)
- Total phosphorus (%): 0.28 (Mill stream pond) and 0.02 (Iron hatch run-off)
- Dry mass (%): 20 (Mill stream pond) and 79 (Iron hatch run-off)
- Sediment samples sieved: Yes

Duration of test (contact time):

100 d

Initial conc.:

108 other: g/ha

Based on:

act. ingr.

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

TEST CONDITIONS
- Volume of test solution/treatment: 43-46 µL
- Test temperature: 20 ± 2°C
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: Borosilicate glass cylinders (ca 4.5 cm diameter)
- Number of culture flasks/concentration: 4
- Method used to create aerobic conditions: During the equilibrium period the aquatic units were slightly agitated on an orbital shaker and moistened carbon dioxide-free air was drawn over the water surface.

- Test performed in closed vessels due to significant volatility of test substance:
- Test performed in open system:
- Details of trap for CO2 and volatile organics if used: The effluent air was passed in series through an empty trap for security followed by ethanediol for polar volatiles, an additional security trap to prevent any contamination of ethanediol with ethanolamine and two ethanolamine traps to collect evolved carbon dioxide.

SAMPLING
Duplicate units from treatment groups A and B were removed for analysis at intervals of 0 (immediately after application), 6, 24 and 48 hours and 7, 14, 30, 59 and 100 days after test substance application. Single units from treatment groups C and D were removed for analysis at intervals of 0 (immediately after application), 7, 30, 59 and 100 days after test substance application. Duplicate units from treatment groups E and F were removed for radiochemical analysis at intervals of 30 and 100 days after test article application and at 29 and 98 days, a small portion (<1 mL) of the water was removed from each vessel for sterility testing.

Compartment:

natural water / sediment: freshwater

% Recovery:

93.79

Remarks on result:

other: Mill stream pond aquatic system (phenyl label)

Compartment:

natural water / sediment: freshwater

% Recovery:

90.13

Remarks on result:

other: Iron hatch run-off aquatic system (phenly label)

Compartment:

natural water / sediment: freshwater

% Recovery:

96.78

Remarks on result:

other: Irradiated Mill stream pond aquatic system (pyridine label)

Compartment:

natural water / sediment: freshwater

% Recovery:

97.36

Remarks on result:

other: Irradiated Iron hatch run-off aquatic system (pyridine label)

Key result

Compartment:

natural water: freshwater

DT50:

0.2 d

Temp.:

20 °C

Remarks on result:

other: Mill stream pond (surface water)

Remarks:

pyridine label

Key result

Compartment:

natural water / sediment: freshwater

DT50:

0.2 d

Temp.:

20 °C

Remarks on result:

other: Mill stream pond (total system)

Remarks:

pyridine label

Key result

Compartment:

natural water: freshwater

DT50:

0.29 d

Temp.:

20 °C

Remarks on result:

other: Iron hatch run-off (surface water)

Remarks:

pyridine label

Key result

Compartment:

natural water / sediment: freshwater

DT50:

0.31 d

Temp.:

20 °C

Remarks on result:

other: Iron hatch run-off (total system)

Remarks:

pyridine label

Transformation products:

yes

Remarks:

DE-535 acid (ca 90 to 92% at 48 h); DE-535 pyridinol which accounted for ca 33% and ca 21% of applied radioactivity in the silty loam and sandy system, respectively after 100 days

No.:

#1

No.:

#2

Volatile metabolites:

yes

Conclusions:

The test substance was rapidly hydrolyzed to DE-535 acid. The DE-535 acid then undergoes microbial degradation resulting in formation of the pyridinol as the major product and extensive mineralization of the phenyl ring. Lower levels of DE-535 phenol and up to four other degradation products are formed. Sediment bound residues are formed as a result of microbial degradation rather than by sorption of parent ester or acid.

Executive summary:

The degradation of (14C)-test substance has been studied in two water-sediment systems (a high organic silty loam sediment and a low organic sandy sediment) over a 100 day period. Two radio-labelled forms of the test substance were used to enable the fate of the pyridine and phenyl ring systems to be studied independently. In addition, one of the radio labelled forms of the test substance was applied to gamma irradiated incubation units to distinguish the purely physicochemical processes from the microbiological processes. The study was conducted to meet the requirements of Biologische Bundesanstalt Guidelines, Part IV, Section 5-1 and also satisfies the requirements of the EC directive 91/414/EEC.

Samples of each water-sediment system were dispensed into glass cylinders (ca 4.5 cm diameter) to produce incubation units containing a 2.5 cm sediment layer covered with associated water to a depth of 6 cm. Moistened carbon dioxide-free air was drawn over the water surface and the units were maintained in the dark at 20 ± 2°C for 47 days (32 days for irradiated units) to enable equilibrium to be established. Following the acclimatization period, (14C)-test substance ester was applied to each unit at a rate equivalent to 108 g ai per ha. The air drawn over the surface of the units was passed through a series of traps to collect evolved volatile radio-labelled material.

Duplicate incubation units treated with (pyridine-4,5-14C)-test substance were removed for analysis at intervals of 0, 6, 24 and 48 hours and 7, 14, 30, 59 and 100 days after test substance application. Single incubation units treated with (phenyl-(UL)-14C)-test substance were removed for analysis at intervals of 0, 7, 30, 59 and 100 days. Duplicate irradiated incubation units treated with (pyridine-4,5-14C)-test substance were removed for analysis at intervals of 30 and 100 days after test substance application. The trap reagents were also collected for analysis and replenished at the same sampling intervals.

The surface water in each incubation unit was separated from the sediment by aspiration. The radioactivity in the water was determined by liquid scintillation counting (LSC) and the water was acidified to prevent base hydrolysis of the test article. Radioactivity in surface water was extracted into ether and analysed for test substance and degradation products by high performance liquid chromatography (HPLC).

Following application of (pyridine-4,5-14C)-test substance, levels of radioactivity in the surface water decreased from ca 80% at zero-time to ca 32% after 100 days in the high organic silty loam system. A similar decrease from ca 74% to ca 31% was observed in the lower organic sandy system. The levels of radioactivity in the sediment extracts were generally higher in the silty loam sediment (ca 40% and 32% after 30 and 100 days respectively) than in the sandy sediment (ca 20% and 11% respectively). In both sediment-water systems, non-extractable radioactivity in the sediment increased from <1% at zero time to ca 9 to 11% after 30 days and ca 25 to 27% after 100 days. Levels of radioactivity in volatile traps were low (<5%) in the silty loam system but higher levels (ca 11% at 100 days) were detected in ethanolamine traps from the sandy system. This was probably due to evolution of 14CO2 at later timepoints which coincided with a decrease in mass balance in the sandy system (ca 88% at 59 days; ca 81% at 100 days) which may have resulted from evolution of other 14C-Iabelled volatile products which were not trapped in the system. Mass balance was ca 93 to 103% for the silty loam system and ca 95 to 100% up to 30 days in the sandy system.

Following application of (phenyl-14C) labelled test substance, the distribution of radioactivity between water and sediment at the early timepoints was similar to that obtained from the (pyridine-14C) label. At later timepoints, levels of radioactivity in ethanolamine traps were higher and accounted for ca 47% and 53% of applied radioactivity in the silty loam and sandy system respectively after 100 days.

In sediment-water systems irradiated to produce sterility, the distribution of radioactivity was very different from non-sterile systems. No volatile products were detected. Non-extractable sediment residues were low (<5 %) throughout the 100-day incubation period and the distribution of radioactivity between water and sediment extracts was very similar at 30 and 100 days for both systems.

Chromatographic analysis of water and sediment extracts following application of (pyridine-14C)-test substance indicated rapid degradation of parent material in both sediment-water systems with <2% remaining after 48 h. A concomitant increase in the levels of DE-535 acid (ca 90 to 92 % at 48 h) was observed. Subsequent degradation of the acid was slower and the major product was DE-535 pyridinol which accounted for ca 33% and ca 21 % of applied radioactivity in the silty loam and sandy system respectively after 100 days. Lower levels (ca 5% and 1% respectively) of the DE-535 phenol were detected. Three unknown degradation products were detected and accounted for maxima of ca 0.8 %, 5.9% and 5.2% of applied radioactivity respectively. In general, the chromatographic profiles obtained after application of the (phenyl-14C) label were qualitatively and quantitatively similar to those obtained for the (pyridine-14C) label (excluding the pyridinol for which no corresponding phenyl ring containing product was detected). A high proportion (ca 15%) of unknown 3 was detected 30 days after application of the (phenyl-14C) labelled test substance to the silty loam system although lower levels (<4 %) were found at all other timepoints. In sediment-water systems irradiated to produce sterility, DE-535 acid was the only major degradation product and accounted for >90% of applied radioactivity after 30 and 100 days.

Degradation half-life (DT-50) values for the test substance in the silty loam and sandy sediment-water systems were 0.2 and 0.3 days, respectively. Corresponding DT-90 values were 0.7 and 1.0 days respectively. Degradation rates in surface water and the total sediment-water system were very similar. Further degradation of the DE-535 acid proceeded with DT-50 values of 43 and 36 days, respectively and DT-90 values of 143 and 120 days, respectively. The stability of DE-535 acid in the sediment-water systems irradiated to produce sterility indicated that initial conversion of the ester to the acid is a chemical hydrolytic process but subsequent degradation of the acid is due to microbial activity.

In summary, the test substance was rapidly hydrolyzed to DE-535 acid. The DE-535 acid then undergoes microbial degradation resulting in formation of the pyridinol as the major product and extensive mineralization of the phenyl ring. Lower levels of DE-535 phenol and up to four other degradation products are formed. Sediment bound residues are formed as a result of microbial degradation rather than by sorption of parent ester or acid.

Reference 2

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

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

(R)-Haloxyfop-Ph-UL-14C methyl ester
Radiochemical purity: 99.1%
Radioactivity: 13.3 mCi
Specific activity: 34.7 mCi/mmol


Haloxyfop methyl pyridine-2,6-14C
Radiochemical purity: 99.1%
Radioactivity: 23.0 mCi
Specific activity: 19.4 mCi/mmol

Radiolabelling:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: freshwater

Details on source and properties of surface water:

- Details on collection: Calwich Abbey lake (Staffordshire, England) which is a shallow lake located at a height of 95 m above sea level. The surface water was filtered through a 100 μm mesh size filter, at collection, prior to use. Sampling depth is 20-30 cm.
- Storage conditions: Refrigerated (ca 4°C)

Parameters measured at field sampling:
Temperature [°C]: 16.1
pH: 8.03
Oxygen concentration [%]: 85.7
Conductivity (ppm): 257
Sampling depth [cm]: 20-30
Colour: Clear, Colourless

Parameters measured post-collection
TOC [mg/L]: 26.4
DOC [mg/L]: 25.8
Conductivity [μS/cm]: 571
pH: 7.8
Total suspended solids [mg/L]: 29.9
EDTA Hardness [mg CaCO3/L]: 222
Nitrate [mg/L]: 19.2
Nitrite [mg/L]: 7.64
Ammonium [mg/L]: 13.7
Phosphate [mg/L]: <0.3
N total [mg/L]: 20.5
P total [mg/L]: <0.1
CBOD [mg/L]: 6.7

Duration of test (contact time):

60 d

Initial conc.:

9 µg/L

Based on:

test mat.

Initial conc.:

90 µg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

TEST CONDITIONS
- Volume of test solution/treatment: Phenyl low dose: 79.0-91.6 μL; Pyridine low dose: 88.0-95.2 μL; Phenyl high dose: 195.0-212.0 μL; Pyridine high dose: 174.0-212.2 μL
- Test temperature: 20 ± 2°C
- pH: 8.40-8.73
- Aeration of dilution water: Moist air passed over samples
- Suspended solids concentration:
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: 250 mL duran flasks
- Number of culture flasks/concentration: 18 (low and high dose test substance concentration); 8 (sterile control); 2 (blank control); 8 (reference control)
- Method used to create aerobic conditions: Moist air passed over samples
- Details of trap for CO2 and volatile organics if used: Individual traps were associated with each sample and air in the system was continuously purged throughout the duration of the study headspace of acidified samples were purged and passed through two consecutive 2M NaOH traps at each timepoint.

SAMPLING
- Sampling frequency: Zero Time, 1, 4, and 8 hours post treatment and then 1, 2, 30 and 60 days post application
- Sampling method used per analysis type: Take aliquots of samples to check sterility (sterile groups only). Sample decanted and weighed. Duplicate aliquots analysed by LSC and aliquots from each sample removed for HPLC analysis. Samples acidified and returned to the rig and for 1 hour. Duplicate aliquots of acidified sample analysed by LSC. Acetonitrile apparatus wash carried out on selected samples with mass balance <95% and duplicate aliquots analysed by LSC.
- Sterility check if applicable: Zero time, Day 1, Day 30 and Day 60 samples checked against a positive and negative control after at least 48 hours exposure
- Sample storage before analysis: -20 ºC

STATISTICAL METHODS: Statistical analyses included calculations of means, standard deviations and correlation coefficients for the interpretation and summarization of results. Regressions, means, standard deviations and correlation coefficients were calculated using Microsoft Excel™. Values calculated using Microsoft Excel™ were calculated from the displayed values as opposed to the maximum precision available. Radiochromatograms were reconstructed from the LSC data pertaining to the HPLC fractions using Laura software (LabLogic, Version 4.2.4.50). Calculations are performed to full precision using the Laura software and the final values have been rounded for the purpose of reporting.

Reference substance:

benzoic acid, sodium salt

Remarks:

10 µg/L

Compartment:

natural water: freshwater

% Recovery:

94.6

Remarks on result:

other:

Remarks:

Recovery of [14C-Phenyl]-test substance applied to surface water at a concentration of 9 μg/L

Compartment:

natural water: freshwater

% Recovery:

95.7

Remarks on result:

other:

Remarks:

Recovery of [14C-Pyridine]-test substance applied to surface water at a concentration of 9 μg/L

Compartment:

natural water: freshwater

% Recovery:

95.8

Remarks on result:

other:

Remarks:

Recovery of [14C-Phenyl]-test substance applied to surface water at a concentration of 90 μg/L

Compartment:

natural water: freshwater

% Recovery:

96.1

Remarks on result:

other:

Remarks:

Recovery of [14C-Pyridine]-test substance applied to surface water at a concentration of 90 μg/L

Compartment:

natural water: freshwater

% Recovery:

97.9

Remarks on result:

other:

Remarks:

Recovery of [14C-Phenyl]-test substance applied to sterilized surface water at a concentration of 90 μg/L

Compartment:

natural water: freshwater

% Recovery:

97.5

Remarks on result:

other:

Remarks:

Recovery of [14C-Pyridine]-test substance applied to sterilized surface water at a concentration of 90 μg/L

Key result

Compartment:

natural water: freshwater

DT50:

14.3 h

Type:

other: Simple first-order

Temp.:

20 °C

Remarks on result:

other: Low concentration (9 μg/L)

Key result

Compartment:

natural water: freshwater

DT50:

16.4 h

Type:

other: Simple first-order

Temp.:

20 °C

Remarks on result:

other: High concentration (9 μg/L)

Transformation products:

yes

Remarks:

Haloxyfop acid (93.2-97.0% at Day 30)

No.:

#1

Details on transformation products:

- Pathways for transformation: The test substance degraded rapidly to its acid derivative via O-demethylation of the methyl ester group. No significant difference was observed between the degradation pattern of mineralisation and sterile groups and therefore the degradation was deemed to be abiotic.

Details on results:

MAJOR TRANSFORMATION PRODUCTS
- Phenyl Low Rate Samples (9 μg/L): HPLC analysis of phenyl low rate surface water samples demonstrated that the test substance accounted for a mean of 91.7% AR at zero time and decreased to 15.1% AR by 48 hours after treatment and at Day 30 no test substance was detected. A single significant degradation product was identified as haloxyfop acid which steadily increased throughout the study reaching a mean maximum value of 93.2% AR at Day 30.
- Pyridine Low Rate Samples (9 μg/L): HPLC analysis of pyridine low rate surface water samples demonstrated that the test substance accounted for a mean of 93.1% AR at zero time and decreased to 13.2% AR by 48 hours after treatment and at Day 30 no test substance was detected. A single significant degradation product was identified as haloxyfop acid which steadily increased throughout the study reaching a mean maximum value of 93.3% AR at Day 30.
- Phenyl High Rate Samples (90 μg/L): HPLC analysis of phenyl high rate surface water samples demonstrated that the test substance accounted for a mean of 90.0% AR at zero time and decreased to 18.9% AR by 48 hours after treatment and at Day 30 no test substance was detected. A single significant degradation product was identified as haloxyfop acid which steadily increased throughout the study reaching a mean maximum value of 96.4% AR at Day 30.
- Pyridine High Rate Samples (90 μg/L): HPLC analysis of high rate surface water samples demonstrated that the test substance accounted for a mean of 92.0% AR at zero time and decreased to 18.5% AR by 48 hours after treatment and at Day 30 no test substance was detected. A single significant degradation product was identified as haloxyfop acid which steadily increased throughout the study reaching a mean maximum value of 97.0% AR at Day 30.
- Sterile Samples (90 μg/L): HPLC analysis of sterile samples demonstrated that the test substance accounted for a mean range of 82.9-89.9% AR at zero time and decreased to 47.7-53.9% AR by 24 hours after treatment and at Day 30 no test substance was detected. A single significant degradation product was identified as haloxyfop acid which steadily increased throughout the study reaching a mean maximum value of 97.2% AR at Day 61.

MINOR TRANSFORMATION PRODUCTS
- Individual minor transformation products did not exceed 1.2-4.7% AR at any time point.

MINERALISATION
- % of applied radioactivity present as CO2 at end of study: The test substance did not mineralize in surface water during the 60 day study. All test systems showed minimal mineralisation with a mean maximum ≤1.7% 14CO2 formed at any individual time point.

Results with reference substance:

Reference controls demonstrated the degradation of [14C]-sodium benzoate to 14CO2 in surface water. The majority of radioactivity was recovered as 14CO2 at 21 days after treatment (14CO2 accounted for a mean of 86.4% AR) indicating that a viable microbial population was established.

Simple First-Order Degradation Rates of the Test Substance in Surface Water:

Concentration	DT50 [hours]	DT90 [hours]	Rate constant, k	R2	Chi2 error%	Prob>t
Low (9μg/L)	14.3	47.4	0.04858	0.9884	4.95	3.69E-18
High (90μg/L)	16.4	54.3	0.04237	0.9879	5.16	3.06E-18

Validity criteria fulfilled:

yes

Conclusions:

The test substance did not mineralize in surface water during the 60 day study. DT50 values of 14.3 and 16.4 hours were calculated for low and high concentration samples respectively. Sterile samples showed identical degradation to each mineralisation group demonstrating the transformation of the test substance in surface water was abiotic.

Executive summary:

The aerobic mineralisation of [14C]-test substance was studied at two concentrations (9 μg/L and 90 μg/L) in one surface water at 20 ± 2°C in the dark for 60 days. The experiment was conducted in accordance with the OECD Guideline 309. Samples were collected at zero time, 1, 4, and 8 hours post treatment, and then at 1, 2, 30 and 60/61 days post treatment. Samples were acidified and connected to a series of trapping solutions to release and collect any 14CO2 in solution. The test substance residues in surface water were analysed by HPLC by direct injection of the surface water samples. Identification of the transformation products was achieved by co-chromatography and LC-MS/MS in select representative samples.

The radioactivity balance was within 89.9-99.9% and 91.9-98.7% of the applied radioactivity (AR) for 9 μg/L and 90 μg/L concentrations, respectively. The concentration of the parent compound decreased from 91.7-93.1 % at zero time, to 13.2-15.1% AR at 2 days post treatment for the 9 μg/L concentration groups; and from 90-92.0% at zero time to 18.5-18.9% AR at 2 days post treatment for the 90 μg/L concentration groups. After 30 days of incubation no test substance was detected. The major transformation product detected was haloxyfop acid, with maximum concentrations of 91.5-94.0% and 93.7-94.8% AR, observed at test termination, for 9 μg/L and 90 μg/L groups, respectively. Minor transformation products did not exceed an individual maximum of 4.7% AR and therefore did not warrant further investigation.

At the end of the study, the evolved CO2 was minimal and did not exceed 1.7% AR in any sample.

The DT50 values of the test substance were 14.3 and 16.4 hours at low and high concentrations, respectively.

Description of key information

 

Study Type	Study Details	Value	Guideline	Reliability
Biodegradation in water and sediment	Aerobic Mineralisation in Surface Water	DT50 14.3 hours (at 9 µg/L) and 16.4 hours (at 90 µg/L)	OECD 309	1
biodegradation in water: sediment simulation testing	Aerobic biodegradation	DT50 0.2 to 0.31 days	Biologische Bundesanstalt Guidelines, Part IV, Section 5-1	1