6-Amino-5-chloro-2-cyclopyrimidine-4-carboxylic acid

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

Study period:

09 May 2007 - 17 Jun 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 308 (Aerobic and Anaerobic Transformation in Aquatic Sediment Systems)

Version / remarks:

2002

Qualifier:

according to guideline

Guideline:

EPA Subdivision N Pesticide Guideline 162-3 (Anaerobic Aquatic Metabolism)

Version / remarks:

1982

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Oxygen conditions:

anaerobic

Inoculum or test system:

natural water / sediment: freshwater

Details on source and properties of surface water:

- Details on collection:Calwich Abbey Lake, Derbyshire, UK
- Storage conditions: at 4°C, aerobic
- Storage length: 19 days
- pH at time of collection: 7.6
- Electrical conductivity: 572
- Hardness (CaCO3): 265
- Dissolved organic carbon (%): 20.7
- Water sieved: yes, (0.212 mm)

Details on source and properties of sediment:

- Details on collection: Silt Loam (Calwich Abbey Lake, Derbyshire, UK)
- Storage conditions: at 4°C, aerobic
- Storage length: 19 days
- Textural classification (i.e. %sand/silt/clay): sand 22%, silt 59%, clay 19% (Silt Loam)
- pH at time of collection: 7.4
- Organic carbon (%): 4.8
- CEC (meq/100 g): 17.5
- Biomass: 897.27μg organic carbon/ g sediment
- Sediment samples sieved: yes (2 mm sieve)

Duration of test (contact time):

365 d

Initial conc.:

0.39 other: µg/g total water

Based on:

act. ingr.

Initial conc.:

13 210 575 other: dpm, 5.951 μCi

Based on:

other: Radioactivity

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

TEST CONDITIONS
- Volume of test solution/treatment: depth: ca. 3 cm sediment, ca. 10.5 cm water /dry sediment: total system water ratio sediment 1: ca. 1:3.8 and sediment 2 ca 1:7.2 based on weight
- Test temperature: 20 ± 2°C
- pH: 6.8 to 8.0 (sediment); 7.3 to 9.2 (surface water)
- pH adjusted: no
- Continuous darkness: yes
- Any indication of the test material adsorbing to the walls of the test apparatus: not applicable

TEST SYSTEM
- Culturing apparatus: Glass incubation vessel, moist air flow through system for aerobic incubation, connections made with glass and PVC tubing
- Number of culture flasks/concentration: 13
- Method used to create aerobic conditions: flow of moist air just below water surface
- Details of trap for CO2 and volatile organics if used: ethanediol to trap non-specific 14C-organic volatiles, and 2M sodium hydroxide to collect 14CO2.
- Other: Acclimatisation period of 14-15 d

SAMPLING
- Sampling frequency: 0, 1, 3, 7, 14, 21, 30, 60, 90, 120, 180, 273 and 365 days post application.
- Sampling method used per analysis type: surface water was separated by decanting or pipetting. Sediments were extracted by heating in a sonic bath at 60°C with 100 mL of 0.2% formic acid:acetonitrile (2:8, v/v) for 30 minutes.
- Sample storage before analysis: at ca. - 20°C, < 30 d

Compartment:

natural water / sediment: freshwater

% Recovery:

96.83

Compartment:

natural water / sediment: freshwater

DT50:

> 365 d

Type:

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

Temp.:

20 °C

Compartment:

natural water / sediment: freshwater

DT50:

> 775 d

Type:

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

Temp.:

12 °C

Remarks on result:

other: Re-calculated using Arrhenius equation.

Transformation products:

no

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

TOTAL UNIDENTIFIED RADIOACTIVITY (RANGE) OF APPLIED AMOUNT:

EXTRACTABLE RESIDUES
- % of applied amount at day 0.001
- % of applied amount at end of study period: 0.098

NON-EXTRACTABLE RESIDUES
- % of applied amount at day 0:0.17
- % of applied amount at end of study period: 17.08 at Day 180, 10.12 at Day 365

MINERALISATION
- % of applied radioactivity present as CO2 at end of study: 0.07

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

Validity criteria fulfilled:

not specified

Conclusions:

The substance is considered to be stable under testing conditions. Significant degradation was not found with a DT50 > 365 d at 20 °C. Instead the substance dissipated gradually from the water phase through partitioning into the sediment.

Reference 2

Endpoint:

biodegradation in water: sediment simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26 Jun 2007 - 03 Jul 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 308 (Aerobic and Anaerobic Transformation in Aquatic Sediment Systems)

Version / remarks:

2002

Qualifier:

according to guideline

Guideline:

EPA Subdivision N Pesticide Guideline 162-4 (Aerobic Aquatic Metabolism)

Version / remarks:

1982

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water / sediment: freshwater

Details on source and properties of surface water:

- Details on collection:
Sediment/ water system 1: Swiss Lake, Chatsworth, Derbyshire, England; sampling debth: 60-70 cm on 18 June, 2007.
Sediment/ water system 2: Calwich Abbey Lake, Derbyshire, UK; sampling debth: 10-15 cm on 19 June, 2007.
- Storage conditions: at 4°C, aerobic
- Storage length: 19 days
- Temperature (°C) at time of collection:
Sediment/ water system 1: 15°C
Sediment/ water system 2: 18°C
- pH at time of collection:
Sediment/ water system 1: 6.2
Sediment/ water system 2: 7.8
- Electrical conductivity (µS/cm):
Sediment/ water system 1: 84
Sediment/ water system 2: 392
- Hardness (CaCO3):
Sediment/ water system 1: 25
Sediment/ water system 2: 197
- Dissolved organic carbon (%):
Sediment/ water system 1: 20.8
Sediment/ water system 2: 18.4
- Water filtered: no

Details on source and properties of sediment:

- Details on collection:
Sediment/ water system 1: Sand (Swiss Lake, Chatsworth, Derbyshire, England); sampling debth: 5-10 cm on 18 June, 2007.
Sediment/ water system 2: Silt Loam (Calwich Abbey Lake, Derbyshire, UK); sampling debth: 0-10 cm on 19 June, 2007.
- Storage conditions: at 4°C, aerobic
- Storage length: 19 days
- Textural classification (i.e. %sand/silt/clay):
Sediment/ water system 1: sand 90%, silt 6%, clay 4% (Sand)
Sediment/ water system 2: sand 8%, silt 74%, clay 18% (Silt Loam)
- pH at time of collection:
Sediment/ water system 1: 5.5 (in water)
Sediment/ water system 2: 7.6 (in water)
- Organic carbon (%):
Sediment/ water system 1: 0.9%
Sediment/ water system 2: 4.6%
- CEC (meq/100 g):
Sediment/ water system 1: 3.2
Sediment/ water system 2: 15.4
- Biomass:
Sediment/ water system 1: 499 μg organic carbon/ g sediment
Sediment/ water system 2: 851 μg organic carbon/ g sediment
- Sediment samples sieved: yes (2 mm sieve)

Duration of test (contact time):

100 d

Initial conc.:

ca. 0.4 other: µg/g total water

Based on:

act. ingr.

Initial conc.:

7 337 850 other: dpm, 3.305 μCi

Based on:

other: Radioactivity

Remarks:

Sand Test System

Initial conc.:

13 448 175 other: dpm, 6.058 μCi

Based on:

other: Radioactivity

Remarks:

Silt Loam Test System

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

TEST CONDITIONS
- Volume of test solution/treatment: depth: ca. 3 cm sediment, ca. 10.5 cm water /dry sediment: total system water ratio sediment 1: ca. 1:3.8 and sediment 2 ca 1:7.2 based on weight
- Solubilising agent (type and concentration if used): acetonitrile (25 mL)
- Test temperature: 20 ± 2 °C
- pH:
sediment: 5.40 to 7.06 (sand), 6.73 to 7.42 (Silt loam)
water: 6.47 to 8.07 (sand), 6.99 to 8.58 (Silt loam)
- pH adjusted: no
- Continuous darkness: yes
- Any indication of the test material adsorbing to the walls of the test apparatus: not applicable

TEST SYSTEM
- Culturing apparatus: Glass incubation vessel, moist air flow through system for aerobic incubation, connections made with glass and PVC tubing
- Number of culture flasks/concentration: 24
- Method used to create aerobic conditions: flow of moist air just below water surface
- Details of trap for CO2 and volatile organics if used: ethanediol to trap non-specific 14C-organic volatiles, and 2M sodium hydroxide to collect 14CO2.
- Other: Acclimatisation period of 18 d

SAMPLING
- Sampling frequency: after 1, 3, 7, 14, 28, 56, 70, 84, and 100 days of incubation
- Sampling method used per analysis type: surface water was separated by decanting or pipetting. Sediments were extracted by heating in a sonic bath at 60 °C with 100 mL of 0.2% formic acid:acetonitrile (2:8, v/v) for 30 minutes.
- Sample storage before analysis: at ca. -20 °C, < 30 d

Compartment:

natural water / sediment: freshwater

% Recovery:

98.11

Remarks on result:

other: sediment/water system 1 (sand)

Compartment:

natural water / sediment: freshwater

% Recovery:

99.57

Remarks on result:

other: sediment/water system 2 (Silt loam)

Compartment:

natural water / sediment: freshwater

DT50:

> 365 d

Type:

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

Temp.:

20 °C

Remarks on result:

other: extrapolated

Remarks:

sediment water system 1

Compartment:

natural water / sediment: freshwater

DT50:

> 365 d

Type:

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

Temp.:

20 °C

Remarks on result:

other: extrapolated

Remarks:

sediment water system 2

Compartment:

natural water / sediment: freshwater

DT50:

> 775 d

Type:

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

Temp.:

12 °C

Remarks on result:

other: Re-calculated using Arrhenius equation for sediment water system 1 + 2.

Transformation products:

no

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

MINOR TRANSFORMATION PRODUCTS
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed: 2.42 at day 0
- Range of maximum concentrations in % of the applied amount at end of study period: 1.11 at day 100

TOTAL UNIDENTIFIED RADIOACTIVITY (RANGE) OF APPLIED AMOUNT:

EXTRACTABLE RESIDUES (sand)
- % of applied amount at day 0: 0.36% AR (total extractable radioactivity)
- % of applied amount at end of study period: 15.27% (total extractable radioactivity)

NON-EXTRACTABLE RESIDUES (sand)
- % of applied amount at day 0: not relevant
- % of applied amount at end of study period: 6.54% AR at Day 70, 6.25% AR at Day 100

MINERALISATION (sand)
- % of applied radioactivity present as CO2 at end of study: 0.68% AR

VOLATILIZATION (sand)
- % of the applied radioactivity present as volatile organics at end of study: 0.04% AR
--------------------------------------------------------------------------------------------------------------------
EXTRACTABLE RESIDUES (Silt loam)
- % of applied amount at day 0: 0.23% AR (total extractable radioactivity)
- % of applied amount at end of study period: 32.07% (total extractable radioactivity)

NON-EXTRACTABLE RESIDUES (Silt loam)
- % of applied amount at day 0: not relevant
- % of applied amount at end of study period: 11.08% AR at Day 56, 10.35% AR at Day 100

MINERALISATION (Silt loam)
- % of applied radioactivity present as CO2 at end of study: 0.23% AR

VOLATILIZATION (Silt loam)
- % of the applied radioactivity present as volatile organics at end of study: none

Validity criteria fulfilled:

not applicable

Conclusions:

The substance is considered to be stable under testing conditions. Significant degradation was not found with a DT50 > 365 d at 20 °C. Instead the substance dissipated gradually from the water phase through partitioning into the sediment.

Description of key information

DT50 water/sediment = > 365 d (OECD 308, aerob and anaerob conditions, 20°C)

DT 50 water/sediment = > 775 d (OECD 308, aerob and anaerob conditions, recalculated to 12 °C)

Additional information

Two studies determining the route and rate of degradation of the test substance are available. Both studies are conducted according to OECD 308 and GLP in the dark at a test temperature of 20±2°C.

The first study assesses the fate of the test substance under anaerobic conditions in an aquatic sediment test system from a natural location. The radiolabelled test substance was applied to the sediment system at a rate of 0.39 μg ai/g of water. Treated vessels were incubated for up to 365 days under anaerobic conditions. Surface water and extractable sediment radioactivity were quantified by LSC. Radioactive components in extractable sediment extracts and surface waters were quantified separately by reversed phase HPLC with on-line radiodetection. Nonextractable test substance residues were quantified by combustion analysis.

The test substance dissipated gradually from the water phase and partitioned to the sediment. No significant degradation products were observed in the surface water or the sediment although an increase in the non-extractable residues indicated that the test substance was incorporated into the sediment organic fraction. The first-order DT50 value for degradation in the water phase, and total system was > 365 days.

In the second study, the route of degradation of the test substance is determined in two aquatic sediment test systems under aerobic conditions. The radiolabelled test item was applied to the two sediment systems at a nominal rate of 0.4 μg a.i./g of water. Treated vessels were incubated for up to 100 days under aerobic conditions. Surface water and extractable sediment radioactivity were quantified by LSC. Radioactive components in extractable sediment extracts and surface waters were quantified separately by reversed phase HPLC with on-line radiodetection. Nonextractable test substance residues were quantified by combustion analysis.

The test substance dissipated gradually from the water phase through partitioning into the sediment. No significant degradation products were observed in the surface water or the sediment although an increase in the non-extractable residues indicated that the test substance was incorporated into the sediment organic fraction. The first-order DT50 value for degradation in the water phase, sediment and total system for was > 365 days for both sediments.