Registration Dossier
Registration Dossier
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EC number: 602-927-1 | CAS number: 123312-89-0
Biodegradation in soil
Administrative data
Link to relevant study record(s)
- Endpoint:
- biodegradation in soil: simulation testing
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 02 Feb 1993 to 06 Oct 1995
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- other: EPA Subdivision N Pesticide Guideline 162-1 and 162-2 (Aerobic and Anaerobic Soil Metabolism Studies)
- Version / remarks:
- October 1982
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- other: Richtlinie für die amtliche Prüfung von Pflanzenschutzmitteln, Teil IV, 4-1: "Verbleib von Pflanzenschutzmitteln im Boden - Abbau, Umbau und Metabolismus".
- Version / remarks:
- December 1986
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- other: Dutch Registration Guideline, Section G.1: Behaviour in Soil; Question G.1.1: Information about the nature of the metabolites and the rate at which these are formed.
- Version / remarks:
- January 1987
- Deviations:
- no
- GLP compliance:
- yes
- Test type:
- laboratory
- Radiolabelling:
- yes
- Remarks:
- [14C]-labelled at position 6 of triazine ring
- Oxygen conditions:
- aerobic/anaerobic
- Soil classification:
- USDA (US Department of Agriculture)
- Year:
- 1 992
- Soil no.:
- #1
- Soil type:
- silt loam
- % Clay:
- 13.9
- % Silt:
- 54.9
- % Sand:
- 31.2
- % Org. C:
- 2.7
- pH:
- 7
- CEC:
- 17.66 meq/100 g soil d.w.
- Soil no.:
- #2
- Soil type:
- loamy sand
- % Clay:
- 5.1
- % Silt:
- 13.5
- % Sand:
- 81.4
- % Org. C:
- 2.2
- pH:
- 7.2
- CEC:
- 14.95 meq/100 g soil d.w.
- Details on soil characteristics:
- - Soil preparation: Before use, the soils were sieved through a 2 mm sieve. If necessary the soil were slightly air-dried prior to sieving.
ADDITIONAL PROPERTIES
Les Evouettes soil (Soil #1)
- Origin: Les Evouettes, VS, Switzerland
- Date of analysis: 27 Oct 1992
- CaCO (%): 7.1
- Total Nitrogen (%): 0.11
- Field capacity (%) (soil moisture at suction pressure of 2.5 pF): 54.4
Collombey soil (Soil #2)
- Origin: Collombey, VS, Switzerland
- Date of analysis: 27 Oct 1992
- CaCO (%): 8.0
- Total Nitrogen (%): 0.27
- Field capacity (%) (soil moisture at suction pressure of 2.5 pF): 29.7 - Soil No.:
- #1
- Duration:
- 361 d
- Soil No.:
- #2
- Duration:
- 361 d
- Soil No.:
- #1
- Initial conc.:
- 0.3 mg/kg soil d.w.
- Based on:
- act. ingr.
- Soil No.:
- #1
- Initial conc.:
- 1.5 mg/kg soil d.w.
- Based on:
- act. ingr.
- Soil No.:
- #2
- Initial conc.:
- 0.3 mg/kg soil d.w.
- Based on:
- act. ingr.
- Soil No.:
- #2
- Initial conc.:
- 1.5 mg/kg soil d.w.
- Based on:
- act. ingr.
- Parameter followed for biodegradation estimation:
- CO2 evolution
- radiochem. meas.
- Soil No.:
- #1
- Temp.:
- 20 ± 1 °C, in the dark.
- Humidity:
- The soil moisture was held at 75% of the field capacity.
- Microbial biomass:
- Day 0: 70.1 mg C/100 g soil; Day 90: 49.9 mg C/100 g soil; Day 180: 54.3 mg C/100 g soil; Day 361: 51.0 mg C/100 g soil
- Soil No.:
- #2
- Temp.:
- 20 ± 1 °C, in the dark.
- Humidity:
- The soil moisture was held at 75% of the field capacity.
- Microbial biomass:
- Day 0: 52.3 mg C/100 g soil; Day 90: 40.7 mg C/100 g soil; Day 180: 45.8 mg C/100 g soil; Day 361: 37.8 mg C/100 g soil
- Details on experimental conditions:
- INCUBATION APPARATUS
The studies were performed in open all-glass gas-flow-systems. The aerobic experiments were continuously ventilated with air at a flow rate of 60 mL/min. For the sterile conditions the air was passed through a 0.2 μm sterile filter. The anaerobic experiment, which was installed after 10 days of aerobic incubation, was waterlogged (200 mL) and ventilated two times per day with nitrogen (60 mL/min) for 30 minutes. The effluent air was passed through:
- 2-methoxyethanol (1x; about 50 mL)
- 0.2 N H2S04 (1x; about 50 mL)
- 2 N NaOH (2x; each about 50 mL)
Depending on the amount of volatile radioactivity found in the various absorption solutions, they were followed over the whole incubation period or omitted after 1-2 months if no radioactivity was trapped. Soil samples for the determination of microbial biomass were incubated in open all-glass gas-flow-systems flasks as described above. No absorption flasks were set up.
EXPERIMENTAL DESIGN
- Sample sizes: 200 g soil (dry weight) per system
- Number of aerobic samples: 33
- Number of aerobic/anaerobic samples: 16
- Number of aerobic/sterile samples: 6
- Number of microbial biomass samples: 24
- Sterilisation: For the sterile experiment, soil samples were autoclaved prior to the treatment.
- Determination microbial biomass: The microbial biomass in the soils was determined by using the respiratory method of Anderson and Domsch
TEST SUBSTANCE PREPARATION
- Stock solution: Prior to the preparations of the treatment solution, about 10.5 mg of radiolabelled test substance was dissolved in accurately 50 mL of acetone. Thereafter, the amount of radioactive material present was determined by LSC (Liquid Scintillation Counting) to be 10.23 mg, i.e. 21.38 MBq (0.58 mCi) with a specific radioactivity of 2.09 MBq/mg (56.49 μCi/mg).
- Treatment solution: For preparation of the treatment solution, a volume of 38.0 mL of the stock solution was transferred into a 100 mL volumetric flask and adjusted with water to the final volume. The content of active ingredient in this solutions was 7.775 mg, i.e. 77. 75 μg/mL.
- 0.3 ppm treatment rate: Volumes of exactly 767 ± 1.4 μl (59.63 μg) of the treatment solution were added to exactly 200 g of soil (based on the soil dry weight). For this purpose, small portions of the treatment solution were added to the soil surface by means of a Hamilton Syringe. After addition of each portion the soil was thoroughly mixed. After the complete application, the soil moisture was adjusted by adding the appropriate amount of water.
- 1.5 ppm treatment rate: The higher treatment rate was set-up for Les Evouettes soil incubated under aerobic and aerobic/anaerobic conditions to facilitate metabolite identification. For this purpose, an aliquot of 50.55 mL (3.93 mg) of the treatment solution was slowly added to 2620 g soil (based on the soil dry weight) under stirring in a kneading machine (Hobart Universal Kitchen Machine, Model N 50). Thereafter, the soil was mixed for additional 10 minutes and the acetone allowed to evaporate. The soil moisture was adjusted by adding the appropriate amount of water. The homogeneous distribution of the test substance in the soil was proven by combustion of five randomly collected aliquots of soil after adjusting the soil moisture. The measured concentration of the test substance in soil was 1.485 ± 0.0058 mg/kg soil dry weight. - Soil No.:
- #1
- % Recovery:
- 98.2
- St. dev.:
- 6.6
- Remarks on result:
- other: Evouettes Soil under Aerobic Conditions
- Remarks:
- Mean recovery and St.Dev calculated by registrant
- Soil No.:
- #2
- % Recovery:
- 98.5
- St. dev.:
- 4.5
- Remarks on result:
- other: Collombey Soil under Aerobic Conditions
- Remarks:
- Mean recovery and St.Dev calculated by registrant.
- Soil No.:
- #1
- % Recovery:
- 100
- St. dev.:
- 4.7
- Remarks on result:
- other: Les Evouettes Soil under 10 Days of Aerobic and 91 Days of Anaerobic Conditions
- Remarks:
- Mean recovery (101.9%) and St.Dev calculated by registrant.
- Soil No.:
- #2
- % Recovery:
- 100
- St. dev.:
- 7
- Remarks on result:
- other: Collombey under 10 Days of Aerobic and 91 Days of Anaerobic Conditions
- Remarks:
- Mean recovery (101.1%) and St.Dev calculated by registrant.
- Soil No.:
- #1
- % Recovery:
- 100
- St. dev.:
- 4.8
- Remarks on result:
- other: Les Evouettes Soil under Aerobic/Sterile Conditions
- Remarks:
- Mean recovery (102.2%) and St.Dev calculated by registrant.
- Key result
- Soil No.:
- #1
- DT50:
- 2.9 d
- Type:
- (pseudo-)first order (= half-life)
- Temp.:
- 20 °C
- Remarks on result:
- other: Les Evouettes Soil under Aerobic Conditions
- Key result
- Soil No.:
- #2
- DT50:
- 2.3 d
- Type:
- (pseudo-)first order (= half-life)
- Temp.:
- 20 °C
- Remarks on result:
- other: Collombey Soil under Aerobic Conditions
- Soil No.:
- #1
- DT50:
- 380.9 d
- Type:
- (pseudo-)first order (= half-life)
- Temp.:
- 20 °C
- Remarks on result:
- other: Les Evouettes Soil under Aerobic/Anaerobic Conditions
- Soil No.:
- #2
- DT50:
- 707.3 d
- Type:
- (pseudo-)first order (= half-life)
- Temp.:
- 20 °C
- Remarks on result:
- other: Collombey Soil under Aerobic/Anaerobic Conditions
- Soil No.:
- #1
- DT50:
- 33 d
- Type:
- (pseudo-)first order (= half-life)
- Temp.:
- 20 °C
- Remarks on result:
- other: Les Evouettes Soil under Aerobic/Sterile Conditions
- Transformation products:
- yes
- Details on transformation products:
- RATES OF DEGRADATION OF THE TEST SUBSTANCE AND MAJOR METABOLITES
Based on the concentration of the parent molecule found after various time intervals the degradation rate constants of the test substance were determined by applying a two-compartment model for the degradation of the parent molecule under aerobic conditions and pseudo first order reaction kinetics for the degradation of the parent molecule under anaerobic and aerobic/sterile conditions. Under aerobic conditions, the test substance was broken down in the Les Evouettes and Collombey soil, with calculated half-lives of 2.9 and 2.3 days, respectively. The calculated DT-90 values for the same soils, were 29 and 18 days, respectively. Under sterile conditions the degradation of the test substance in Les Evouettes was slower, with DT-50 and DT-90 values of 33 and 110 days. Under aerobic/anaerobic conditions degradation of the test substance in both soils was only observed during the 10 days aerobic phase (average half-life 2.5 days). In the following anaerobic phase practically no degradation was observed. Under all incubation conditions, four major degradation products (M1, UM3, M8 and M2), reaching values of ~ 10% of the radioactivity applied were observed. The half-lives of these degradation products were calculated based on the concentration of the molecule found at various time intervals after reaching the maximum concentration in the system. The degradation rate constants were determined by applying pseudo first order reaction kinetics. Metabolite M1 disappeared with half-lives of 123 and 12.3 days from aerobic incubated Les Evouettes and Collombey soil systems, respectively. In the same soils during anaerobic conditions, M1 was broken down with calculated half-lives of 77 and 82 days, respectively. Metabolite fraction UM3 disappeared with half-live of 45 and 39 days from aerobic incubated Les Evouettes soil and anaerobic incubated Collombey soil, respectively. The calculated half-life for M8 in Collombey soil under aerobic conditions was 127 days. M2 was degraded in Collombey soil with calculated half-lives of 62 and 50 days incubated under aerobic and anaerobic conditions, respectively. In aerobic incubated Les Evouettes soil, M2 disappeared with a DT-50 value of 291 days. All extracted metabolites had a transient character.
DEGRADATION PATHWAY OF THE TRIAZINERING MOIETY IN SOIL
HPLC analysis of extracts of soils incubated under the various conditions, showed that
The test substance was mainly metabolised under aerobic conditions. Practically no degradation was observed under anaerobic conditions, and only minor degradation was found under sterile conditions. Therefore, the discussion will be limited to the aerobic breakdown of the molecule. Beside the parent molecule, twelve metabolite fractions could be detected. However, only five of these metabolite fractions reached significant amounts of> 5% of the radioactivity initially applied. The individual metabolites were separated and purified by a series of HPLC runs on RP18 columns. The structures of the purified metabolites were proven by co-chromatography on HPLC and 2D-TLC and by comparative mass spectrometry. The structure of metabolite fraction M1 was further analysed by proton nuclear magnetic resonance spectrometry. The test substance was first degraded to metabolite M1, reaching with 24.9 and 30.7% of the dose applied its highest concentrations after 14 days in Les Evouettes and 3 days in Collombey soil, respectively. For structure identification of metabolite M1 by proton nuclear magnetic resonance and mass spectrometry, isolated amounts of M1 from the present study (about 6 μg) and metabolite M1-TH (about 35 μg) were combined. Metabolite M1 was further degraded following at least 3 metabolic pathways. One major pathway was the degradation of the molecule by oxidation ·at the pyridine moiety, yielding metabolite M2, reaching at highest 11 % and 24% of the applied radioactivity in Les Evouettes and Collombey soil, respectively. Metabolite M2 was further degraded by oxidation of the triazine hydroxy group to the corresponding ketone forming metabolite M8, which accounted for maximally 8.2 and 10% of the dose in Les Evouettes and Collombey soil, respectively. M8 was subsequently metabolized by cleavage between the triazine and the pyridine rings leading to M5, followed by mineralization to CO2. Metabolite M5 was formed in maximum quantities of 4.4 and 5.4% in Les Evouettes and Collombey soil, respectively. Minor routes of degradation were leading to M9, which was detected only in Collombey soil (2.8% at day 3), and M5. Metabolite M5 accounted for maximally 4.4% in Les Evouettes soil. In Collombey soil metabolites UM3, M5 and M9 were determined to maximally 4.2, 5.4 and 2.8%, respectively. Polar and transient metabolite UM3 proved to be resistant against mild acidic (0.1 N HCl 7 days room temp.; 3 min 80°C) and basic (0.1 N NaOH 6 days room temp.; 3 min 80°C) conditions. Only under strong acidic conditions (5 N HCl after heating for 5h at 120°C, UM3 was partly degraded into 2-3 fractions which could not be further analysed. When UM3 was submitted to mass spectrometry a molecular weight of 380 da but no fragmentation was observed. Furthermore, it was found that UM3 was a unique metabolite formed only from the triazine ring labelled compound and not from the pyridine ring labelled compound. Therefore, it is concluded that UM3 represented a stable conjugate of the triazine moiety or fragments of it with natural constituents of the soil. All metabolites formed were transient in nature. The pronounced formation of 14C-CO2 (up to 30% of the applied radioactivity after 361 days) indicated the complete breakdown of the triazine moiety with time. - Evaporation of parent compound:
- no
- Volatile metabolites:
- no
- Remarks:
- No radioactivity (<0.1 %) other than 14C-CO2 was detected.
- Residues:
- yes
- Remarks:
- See 'Details on results'
- Details on results:
- MICROBIAL BIOMASS
At the beginning of the study, microbial biomass was 70.1 and 52.3 mg microbial carbon per 100 g soil for Les Evouettes and Collombey soil, respectively. In Les Evouettes soil, the microbial biomass decreased during incubation to 49.9, 54.3, and 51.0 mg C/100 g soil after 90, 180, and 361 days of incubation, respectively. For the same period, the corresponding microbial biomass in Collombey soil was 40.7, 45.8, and 37.8 mg C/100 g soil. These values indicate, that sufficient microbial activity was present in both soils at the beginning of the study, approaching lower values for both soils at the end of the incubation period. Therefore, a certain influence of the decreasing biomass on the degradation rates of the parent molecule and various metabolites within the increasing incubation period may be assumed.
RECOVERY AND RADIOACTIVITY
The recovery of radioactivity for the aerobic incubation was, on average, 98.2 ± 6.57% and
98.8 ± 4.53% for Les Evouettes and Collombey soil, respectively. For the same soils incubated under anaerobic conditions, the corresponding values were 101.9 ± 4.72% and 101.0 ± 7.03%. The recovery for Les Evouettes soil incubated under sterile aerobic conditions was on average 102.1 ± 4.81 % of the radioactivity applied. On average for all incubated soil systems, the recovery of radioactivity was 99.6 ± 5.6%. The lowest observed recovery was 90.1 % and the corresponding maximum value was 109.3% of the radioactivity applied.
EXTRACTABILITY
For the test substance incubation under aerobic conditions, extractable radioactivity steadily decreased with time, finally reaching 18.8 and 5.8% of the radioactivity applied to Les Evouettes silt loam and Collombey loamy sand, respectively. Accordingly, the non-extractable fraction increased in the same samples up to 50.6 and 63.7% of the dose initially applied. Under aerobic/anaerobic conditions; the extractable fraction decreased within the 10 days of aerobic incubation to 86.2 and 85.6% of the radioactivity applied in Les Evouettes and Collombey soil, respectively. During the following anaerobic incubation period of three months, a slower but continuous decrease of extractable radioactivity could be observed, reaching lowest values of 62.2 and 55.1 % of the dose initially applied to Les Evouettes and Collombey soil, respectively. For the same samples, the non-extractable fraction increased to 35.1 and 51.0% of the radioactivity applied. For the test substance incubation in Les Evouettes soil under aerobic/sterile conditions, extractable radioactivity decreased to 68.7% of the dose applied. The corresponding non-extractable fraction increased to 29.7% of the radioactivity initially applied. The radioactivity liberated by harsh extraction procedures from soil samples after one year of aerobic incubation was 4.2 and 1.8 % of the radioactivity applied to Les Evouettes and Collombey soil, respectively. After three months of anaerobic incubation the radioactivity extracted by this procedure was 3.2 and 4.0% of the dose applied to Les Evouettes and Collombey soil, respectively. For sterile incubated Les Evouettes soil the radioactivity liberated by harsh extraction procedures was only 3.9% of the dose initially applied. No further attempts to analyse this minor amounts of liberated radioactivity were made.
BOUND RESIDUE FRACTIONATION
Non-extractables of aerobic incubated Les Evouettes and Collombey soil after harsh extraction
were further submitted to bound residue fractionation. The major radioactive fraction in both soils was the humin fraction, accounting for 44.8 and 60.3% of the dose applied to Les Evouettes and Collombey soil, respectively. For both soils, the fulvic acid fraction and the humic acid fraction were only 1.4 and 0.2% of the radioactivity initially applied to the soils, respectively.
VOLATILES
Under all incubation conditions, no other volatile radioactivity (<0.1 %) than 14C-CO2 could be detected. For aerobic incubation of the test substance, 14C-CO2 reached after one year of incubation 23.6 and 30.0% of the radioactivity applied to Les Evouettes and Collombey soil, respectively. For the same soils incubated under aerobic/anaerobic conditions, the formation of 14C-CO2 was mainly observed during the aerobic period, accounting after ten days of incubation for 1.2 and 1.6% of the radioactivity applied. Thereafter, only low amounts of 14C-CO2 were formed, reaching after 3 months of anaerobic incubation 2.4 and 2.5% of the radioactivity applied, respectively. Under aerobic/sterile incubation conditions practically no volatile radioactivity (≤1 %) was observed. - Conclusions:
- The aerobic, anaerobic and aerobic/sterile DT50 values in the Les Evouettes soil were 2.9, 381 and 33 days, respectively. The aerobic and anaerobic DT50 values in the Collombey soil were 2.3 and 707 days, respectively.
- Executive summary:
Two soils were treated with radiolabelled test substance (labelled in the triazine ring) at the highest proposed field use rate of 0.3 kg a.i. per ha and incubated under aerobic (361 days), aerobic/anaerobic (90 days) and aerobic/sterile (90 days) conditions in the laboratory at a temperature of 20°C. The study was performed in accordance with BBA Part IV, 4-1 and in compliance with GLP. The objectives of the study were to provide information on the rate of degradation of the test substance, the rate of formation and decline of degradation products and to determine its metabolic pathway in soil. The study has shown that the test substance was rapidly broken down in soil with half-lives lower than one week under aerobic incubation conditions. Under aerobic/sterile conditions, the half-life of the test substance was about one month, demonstrating the abiotic degradability of the test substance. Practically no degradation of the parent molecule was observed under anaerobic incubation conditions. The aerobic, anaerobic and aerobic/sterile DT50 values in the Les Evouettes soil were 2.9, 381 and 33 days, respectively. The aerobic and anaerobic DT50 values in the Collombey soil were 2.3 and 707 days, respectively.
The recovery of radioactivity was, on average, 98.2±6.57% and 98.5±4.53% for Les Evouettes and Collombey soil, respectively. For the same soils incubated under anaerobic conditions, the corresponding figures were 101.9±4.72% and 101.0±7.03%. The recovery for Les Evouettes soil incubated under sterile aerobic conditions was on average 102.1±4.81 % of the radioactivity applied. On average for all incubated soil systems, the recovery of radioactivity was 99.6±5.6%. Under aerobic incubation conditions,the test substancewas mainly degraded into M1, which was further degraded after at least 3 different degradation pathways. One major pathway was the degradation of the molecule by oxidation at the pyridine moiety, yielding metabolite M2, reaching at highest 11% and 24% of the applied radioactivity 90 and 29 days after treatment in Les Evouettes and Collombey soil, respectively. M2 was further degraded by oxidation of the triazine hydroxy group to the corresponding ketone forming metabolite M8, which accounted for maximally 8.2 (day 239) and 10% (day 14) of the dose in Les Evouettes and Collombey soil, respectively. M8 was subsequently metabolized by cleavage between the triazine and the pyridine rings leading to M5 which was formed in maximum quantities of 4.4 and 5.4%, 29 days after treatment in Les Evouettes and Collombey soil, respectively.
Under anaerobic and sterile conditions no metabolites other than those observed under aerobic conditions were formed. Non-extractable radioactivity accounted for 50.6, 63.7 and 29.7% of the dose applied in aerobic incubated Les Evouettes and Collombey soil and sterile incubated Les Evouettes soil, respectively. Harsh extraction procedures of soils from incubation day 361 liberated only marginal amounts of radioactivity (≤4.2%). Organic matter fractionation with aerobic incubated soils after the harsh extraction procedure demonstrate that the major radioactive fraction in both soils was the humin fraction, accounting for 44.8 and 60.3% of the dose applied in Les Evouettes and Collombey soil, respectively. For both soils, the fulvic acid fraction and the humic acid fraction were only 1.4 and 0.2% of the radioactivity initially applied to the soils, respectively. Furthermore, it was clearly demonstrated, that the triazine ring moiety was considerably mineralized to carbon dioxide accounting for up to 30 and 23.6% of the dose applied after one year of incubation in Les Evouettes and Collombey soil, respectively. Therefore, it can be assumed that the triazine ring moiety of the test substance will completely disappear from soil environment with time.
- Endpoint:
- biodegradation in soil: simulation testing
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 31 Jul 1992 to 31 Oct 1995
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- other: Richtlinie für die amtliche Prüfung von Pflanzenschutzmitteln, Teil IV, 4-1: "Verbleib von Pflanzenschutzmitteln im Boden - Abbau, Umbau und Metabolismus".
- Version / remarks:
- December 1986
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- other: EPA Subdivision N Pesticide Guideline 162-1 and 162-2 (Aerobic and Anaerobic Soil Metabolism Studies)
- Version / remarks:
- October 1982
- Deviations:
- no
- GLP compliance:
- yes
- Test type:
- laboratory
- Radiolabelling:
- yes
- Remarks:
- [14C]-labelled at position 6 of triazine ring
- Oxygen conditions:
- aerobic
- Soil classification:
- USDA (US Department of Agriculture)
- Year:
- 1 992
- Soil no.:
- #1
- Soil type:
- silt loam
- % Clay:
- 13.6
- % Silt:
- 56.9
- % Sand:
- 29.5
- % Org. C:
- 2.3
- pH:
- 7.3
- CEC:
- 14 meq/100 g soil d.w.
- Soil no.:
- #2
- Soil type:
- loamy sand
- % Clay:
- 5.6
- % Silt:
- 12
- % Sand:
- 82.4
- % Org. C:
- 1.9
- pH:
- 7.2
- CEC:
- 13.9 meq/100 g soil d.w.
- Soil no.:
- #3
- Soil type:
- sand
- % Clay:
- 6.9
- % Silt:
- 8.7
- % Sand:
- 84.7
- % Org. C:
- 1.98
- pH:
- 6.6
- CEC:
- 11.6 meq/100 g soil d.w.
- Details on soil characteristics:
- - Soil preparation: Soils were passed through a 2 mm sieve and the moisture content determined by drying triplicate sub-samples in an oven at 120°C for 16 hours.
- Moisture determination: The sieved soils contained 23.1% (Les Evouettes), 6.3% (Collombey) and 2.5% (Speyer) water by weight. The maximum water holding capacity (MWC) of each soil was also determined. For each soil separately, a glass column (4 cm internal diameter), fitted with a stopcock and plugged with sand or cotton wool, was filled with sieved soil to a height of 30 cm. The column was infiltrated with water from below until the water level was 3 - 5 cm above the soil surface. The column was left in this state for 24 hours to ensure complete saturation, when it was then allowed to drain - once this was complete, the soil was removed from the column and the water content of the soil determined as described above. See 'Any other information on materials and methods incl. tables' for the calculated MWC values per soil.
ADDITIONAL PROPERTIES
Les Evouettes soil (Soil #1)
- CaCO (%): 8.4
- Total Nitrogen (%): 0.28
Collombey soil (Soil #2)
- CaCO (%): 8.10
- Total Nitrogen (%): 0.23
Speyer 2.2 soil (Soil #3)
- CaCO (%): 0.00
- Total Nitrogen (%): 0.18 - Soil No.:
- #1
- Duration:
- 122 d
- Soil No.:
- #2
- Duration:
- 122 d
- Soil No.:
- #3
- Duration:
- 180 d
- Initial conc.:
- 1 mg/kg soil d.w.
- Based on:
- test mat.
- Remarks:
- 2.5 times the normal field application rate
- Parameter followed for biodegradation estimation:
- CO2 evolution
- radiochem. meas.
- Soil No.:
- #1
- Temp.:
- 20 °C
- Humidity:
- See 'Any other information on materials and methods incl. tables'
- Microbial biomass:
- At the start of the study, the biomass was high ranging from 93 - 96 mg carbon/100 g soil. After about six months incubation, the biomass in these soils had decreased significantly, to 42 - 59 mg carbon/100 g soil.
- Soil No.:
- #2
- Temp.:
- 20 °C
- Humidity:
- See 'Any other information on materials and methods incl. tables'
- Microbial biomass:
- At the start of the study, the biomass was high ranging from 93 - 96 mg carbon/100 g soil. After about six months incubation, the biomass in these soils had decreased significantly, to 42 - 59 mg carbon/100 g soil.
- Soil No.:
- #3
- Temp.:
- 20 °C
- Humidity:
- See 'Any other information on materials and methods incl. tables'
- Microbial biomass:
- A low biomass (34 mg carbon/100 g soil) was observed at the start of the study.
- Details on experimental conditions:
- EXPERIMENTAL DESIGN
- Test apparatus: During the acclimatisation period (14 days) the dishes of soil were housed on stainless steel racks in glass columns in a temperature-controlled room at 20°C in darkness. Humidified air was passed through each column to prevent drying out of the soils. Following test substance application, the dishes (with the exception of those taken for time-zero analysis) were adjusted to the desired water content and transferred back into the glass columns at 20°C in darkness, so that for each soil type, two columns were established, each initially containing 10 dishes of soil. (During the acclimatisation and incubation periods, recorded temperatures lay in the range 19.3 - 20.5°C). Each column was connected into a separate gas-flow system arranged in series as follows:
a) water bottle to humidify the air flow;
b) glass column housing the treated soil dishes, containing in the outlet (neck), polyurethane foam bungs;
c) empty trap to prevent transfer of trapping solutions into the column;
d) trap 1 containing 2-(2-ethoxyethoxy)ethanol (ethyl digol);
e) trap 2 containing 2M aqueous potassium hydroxide solution;
f) trap 3 containing 0.1M hydrochloric acid.
- Biomass determination: Additional dishes of soil (60 g dry weight) were established for subsequent measurement of the microbial biomass. These soils were acclimatised, housed and maintained under the same conditions as the treated soils (although no trapping solutions were employed). A further flask of untreated soil with associated foam bungs and trapping solutions was also established to provide radioassay blanks for the trapping media. The microbial biomass of each soil type was determined according to a published method. Determinations were made at the start of the study (two days prior to test substance application) and after 193 days incubation, using soil samples established for this purpose.
- Details of traps for CO2 and organic volatile, if any: The purpose of the foam bungs and ethyl digol was to trap neutral volatile organic compounds including any volatilised test substance. The purpose of the potassium hydroxide trap was to trap 14CO2. During the study, a stream of air was passed continuously through each system at a rate of approximately 50 mL/minute. A further flask of untreated soil with associated foam bungs and trapping solutions was also established to provide radioassay blanks for the trapping media.
TEST SOLUTION APPLICATION
A solution of the radiolabelled test substance in acetone was prepared at a concentration of about 0.27 mg/mL. For each soil type a total of 22 soil dishes were treated with the radiolabelled test substance. Aliquots (230 μL) of this application solution were evenly applied to the surface of each soil with no subsequent mixing. Once the solution had been applied, each dish was weighed and made up to the desired water content (40% MWC). The quantity of test substance applied to each soil was accurately determined by dispensing seven 230 μL aliquots of the application solution, taken at different times during the applications, into 50 mL volumetric flasks containing acetonitrile. These flasks were made up to volume and triplicate aliquots (1 mL) radioassayed. From these measurements, each soil received 7.5912E+06 dpm (3.42 μCi, 127 kBq); this rate was equivalent to 63 μ.g test substance per soil sample or 1.04 μg/g (mg/kg) soil (dry weight), or 0.27 kg/ha on a surface area basis. The dishes of soil destined for subsequent measurement of biomass were treated with the same volume (i.e. 230 μ.L) of acetone. - Soil No.:
- #1
- % Recovery:
- 94.7
- St. dev.:
- 3.5
- Remarks on result:
- other: Recovery and St. Dev. calculated by registrant
- Soil No.:
- #2
- % Recovery:
- 93.8
- St. dev.:
- 3.2
- Remarks on result:
- other: Recovery and St. Dev. calculated by registrant
- Soil No.:
- #3
- % Recovery:
- 96.2
- St. dev.:
- 1.6
- Remarks on result:
- other: Recovery and St. Dev. calculated by registrant
- Key result
- Soil No.:
- #1
- DT50:
- 5.4 d
- Type:
- (pseudo-)first order (= half-life)
- Temp.:
- 20 °C
- Key result
- Soil No.:
- #2
- DT50:
- 4.8 d
- Type:
- (pseudo-)first order (= half-life)
- Temp.:
- 20 °C
- Key result
- Soil No.:
- #3
- DT50:
- 29.1 d
- Type:
- (pseudo-)first order (= half-life)
- Temp.:
- 20 °C
- Transformation products:
- yes
- Details on transformation products:
- The degradation products of the radiolabelled test substance were quantified by HPLC method 2. The major degradation product, and most likely the initial metabolite of the test substance in soil, was M1. This component corresponded, in two chromatographic systems. In Les Evouettes silt loam and Collombey loamy sand soils, the levels of M1 increased from 18-21 % AR after 3 days to 34 - 38% AR after 7 or 14 days, and then declined thereafter. In Speyer 2.2 sand soil peak levels (ca. 15 % AR) of M1 were observed slightly later, after 33 days incubation. Calculated dissipation half-lives for M1 were 43.1, 20.8 and 66.0 days for Les Evouettes, Collombey and Speyer soils, respectively. A region of the chromatogram close to the solvent front contained at least two components (M5 and H3(not further identified)), together with the poorly defined region in between (H2; not further identified). In Les Evouettes and Collombey soils the level of M5 increased to 8 - 11 % AR after 33 - 60 days incubation and then declined thereafter. In Speyer 2.2 soil the level of M5 continued to rise throughout the study to about 13 % AR after 180 days. Although M5 chromatographed close to the solvent front it was likely to be comprised of mainly one component. Maximal levels of component H3 were similar to those of M5, representing up to 8 - 12% AR in the three soil types. Again, peak levels were reached in Speyer 2.2 soil later (122 days) than in the other two soil types (33 days). Component/region H2 represented up to 5 - 8 % AR in Les Evouettes and Collombey soil and up to about 4% AR in Speyer 2.2 soil.
- Evaporation of parent compound:
- no
- Volatile metabolites:
- not specified
- Remarks:
- Not specified other than CO2
- Residues:
- not specified
- Details on results:
- The results are tabulated in 'Any other information on results incl. tables'.
RECOVERY
For each soil sample, the material balance of radioactivity was calculated as the sum of extracted, non-extracted and volatile radioactivity. The recoveries of radioactivity from all soils treated with the radiolabelled test substance were in the range 86.2 - 100.5% applied radioactivity (% AR), and all except four of these were greater than 90% AR.
VOLATILES
Production of volatile radioactivity from Les Evouettes silt loam and Collombey loamy sand soils was similar throughout the study, amounting to about 19% AR after 122 days incubation. Production from Speyer 2.2 sand soil was lower, amounting to about 11 % AR after 122 days and about 16% AR after 180 days incubation. All of the volatile radioactivity in each case was trapped by aqueous potassium hydroxide solution, and was characterised as 14CO2 as, following the addition of saturated barium chloride solution, the radioactivity was detected exclusively in the precipitate. Evolution of 14CO2 from all three soil types occurred at a fairly constant rate throughout the study.
EXTRACTION OF RADIOACTIVITY FROM SOIL
The quantities of radioactivity extracted by solvents declined from about 95 % AR at time zero to about 20- 30% AR after 122 days incubation (Les Evouettes and Collombey soils) and about 33% AR after 180 days incubation (Speyer 2.2 soil). Although the proportion of extractable radioactivity recovered in the initial acetone/water extracts declined with time, the absolute recoveries (in terms of % AR) in the water and acetone reflux extracts remained fairly constant throughout. Non-extractable radioactivity increased from 1 - 3 % AR at time zero to 40 - 50 % AR after 122 or 180 days incubation.
CHROMATOGRAPHIC ANALYSIS OF SOIL EXTRACTS
- Selection of systems: All extracts were analysed by TLC in solvent system A and also by HPLC (method 2). Both methods separated the test substance and a number of degradation products, although as the HPLC method provided the better resolution (especially of the test substance itself), this system was chosen for their quantification. The TLC method also apparently over-estimated the amount of test substance, compared with HPLC, particularly in later samples. This was shown - after chromatography (TLC) of extracts from a 60 days incubated sample, excision of the 'test substance' band, extraction and re-chromatography by HPLC - to be due to other degradation products migrating with a similar Rf to the test substance. HPLC method 2 and TLC systems A and D were used for co-chromatographic analyses of the reference substances with test extracts.
- Quantification of the test substance in soil: Extracts of soil taken for analysis immediately after test substance application contained single radioactive components corresponding to the test substance. This demonstrated the stability and quantitative recovery of the test substance during extraction and chromatography. In Les Evouettes silt loam and Collombey loamy sand soils the degradation of the radiolabelled test substance appeared to be slightly biphasic. The main rapid phase saw the mean proportion of the test substance in soil decline from 91 - 92% AR at time zero to 5 - 6% AR after 33 days. After 122 days the test substance represented about 1 % AR in these soils. This probably reflected the decreasing microbiological activity of these soils with time through carbon starvation. It is well documented that in sieved soils the organisms outgrow their carbon source and therefore microbiological activity decreases with time. This conclusion is supported by the decline in microbial biomass in these soils during the study. Due to its very low microbial biomass the rate of degradation in Speyer 2.2 sand soil was considerably lower than in the other soil types and was fairly constant throughout, such that the mean proportion of the test substance declined from 91 % AR at time zero to 5 % AR after 180 days. - Conclusions:
- DT50 and values for the test substance were 5.4, 4.8 and 29.1 days for Les Evouettes, Collombey and Speyer 2.2 soils, respectively.
- Executive summary:
The degradation of the test substance was studied in three soil types under aerobic conditions: a silt loam (Les Evouettes), a loamy sand (Collombey) and a sand (Speyer 2.2). The study was performed in accordance with BBA Part IV, 4-1 and in compliance with GLP. The test substance, labelled with carbon-14 in its triazine ring, was applied to soil at a rate of 1.0 mg/kg. Soils were incubated in darkness at 20°C for periods of up to four or six months. Total recoveries of radioactivity from all soil samples were in the range of 86.2 - 100.5 % of the amount applied. The quantities of radioactivity extracted by solvents declined from about 95 % applied radioactivity at time zero to about 20 - 30% applied radioactivity after 122 days incubation (Les Evouettes and Collombey soils) and about 33 % applied radioactivity after 180 days incubation (Speyer 2.2 soil). Although the proportion of extractable radioactivity recovered in the initial acetone/water extracts declined with time, the absolute recoveries (in terms of % applied radioactivity) in the water and acetone reflux extracts remained fairly constant throughout. Non-extractable radioactivity increased from 1 - 3 % applied radioactivity at time zero to 40 - 50 % applied radioactivity after 122 or 180 days incubation. The proportion of unchanged test substance in Les Evouettes and Collombey soils declined exponentially to 5 - 6% of the amount applied after 33 days incubation and to about 1 % after 122 days. The test substance was degraded more slowly in Speyer 2.2 soil and at a fairly constant rate over 180 days of incubation. DT50 and values for the test substance were 5.4, 4.8 and 29.1 days for Les Evouettes, Collombey and Speyer 2.2 soils, respectively.
Volatile radioactivity, which was entirely associated with 14CO2 , was evolved at fairly constant rates from all three soil types. In Les Evouettes and Collombey soils this amounted to about 19% applied radioactivity after 122 days, while in Speyer 2.2, production was lower, amounting to about 16% applied radioactivity after 180 days. Extractable degradation products were separated and quantified by high performance liquid chromatography. This resolved around six metabolites of the test substance, of which the major species (M1) represented up to 34 - 38% applied radioactivity in Les Evouettes and Collombey soils after 7 or 14 days. This component, which was the initial metabolite of the test substance, was formed in Speyer 2.2 soil at a lower rate and to a lesser extent (ca. 15% applied radioactivity after 33 days). Metabolite M1 disappeared from Les Evouettes, Collombey and Speyer soils with half-lives of 43.1, 20.8 and 66.0 days, respectively. Another major component (M5) which represented a maximum of 8 - 11 % applied radioactivity in Les Evouettes and Collombey soils after 33 - 60 days, but whose level continued to rise throughout the study in Speyer 2.2 soil (to 13 % applied radioactivity after 180 days). This metabolite is derived from test substance by hydrolysis of the diazo bond and oxidation of the carbon-5 atom in the triazine ring.
- Endpoint:
- biodegradation in soil: simulation testing
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 04 Jul 1994 to 27 Oct 1995
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- other: EPA Subdivision N Pesticide Guideline 162-1 and 162-2 (Aerobic and Anaerobic Soil Metabolism Studies)
- Version / remarks:
- October 1982
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- other: Richtlinie für die amtliche Prüfung von Pflanzenschutzmitteln, Teil IV, 4-1: "Verbleib von Pflanzenschutzmitteln im Boden - Abbau, Umbau und Metabolismus".
- Version / remarks:
- December 1986
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- other: Dutch Registration Guideline, Section G.1: Behaviour in Soil; Question G.1.1: Information about the nature of the metabolites and the rate at which these are formed.
- Version / remarks:
- January 1987
- Deviations:
- no
- GLP compliance:
- yes
- Test type:
- laboratory
- Radiolabelling:
- yes
- Remarks:
- [14C]-labelled at position position 5 of the pyridine ring
- Oxygen conditions:
- aerobic
- Soil classification:
- USDA (US Department of Agriculture)
- Year:
- 1 993
- Soil no.:
- #1
- Soil type:
- silt loam
- % Clay:
- 13.9
- % Silt:
- 54.3
- % Sand:
- 31.8
- % Org. C:
- 2.1
- pH:
- 7.3
- CEC:
- 14 meq/100 g soil d.w.
- Soil no.:
- #2
- Soil type:
- sandy loam
- % Clay:
- 11.8
- % Silt:
- 23.7
- % Sand:
- 64.5
- % Org. C:
- 1.7
- pH:
- 7.2
- CEC:
- 11.9 meq/100 g soil d.w.
- Details on soil characteristics:
- PROPERTIES OF THE SOILS
- Preparation: Before use, the soils were sieved through a 2 mm sieve. If necessary the soils were slightly air-dried prior to sieving.
An overview of the soil characteristics is presented in 'Any other information on materials and methods incl. tables'. - Duration:
- 363 d
- Initial conc.:
- 0.3 mg/kg soil d.w.
- Based on:
- act. ingr.
- Remarks:
- recommended field rate
- Initial conc.:
- 3 mg/kg soil d.w.
- Based on:
- act. ingr.
- Remarks:
- high dose rate for isolation of metabolites
- Parameter followed for biodegradation estimation:
- CO2 evolution
- radiochem. meas.
- Temp.:
- 20 ± 0.7°C
- Humidity:
- The soil moisture was held at 75% of the field capacity. It was adjusted weekly during the first month and thereafter in about two-weeks intervals.
- Microbial biomass:
- See 'Any other information on materials and methods incl. tables'.
- Details on experimental conditions:
- INCUBATION
- System: The studies were performed in open all-glass gas-flow-systems.
- Ventilation: The aerobic experiments were continuously ventilated with air at a flow rate of 60 mL/min. The effluent air was passed through 0.2 N H2SO4 (1x; about 50 mL) and 2 N NaOH (2x; each about 50 mL). Depending on the amount of volatile radioactivity found in the various absorption solutions, they were followed over the whole incubation period or omitted after 1-2 months if no radioactivity was trapped.
- Microbial biomass samples: Soil samples for the determination of microbial biomass were incubated in open all glass gas-flow-systems as described here. No absorption flasks were set up.
EXPERIMENTAL DESIGN
- Sample sizes: 200 g soil d.w. per system
- Number of replication treatments: 2 per time point for the 0.3 mg/kg treatment. 6 samples were used for the 3 mg/kg treatment.
PREPARATION OF THE RADIOLABELLED TEST SUBSTANCE
For the preparation of the stock-solution 9.49 mg of [5-14C] pyridine-test substance was dissolved in 50 ml of acetone. For preparation of application-solution-1, used for the low dosed samples, 20 mL of the stock-solution were taken and made up to 50 mL by addition of water. The final concentration of the test substance in application-solution-1 was 3.93 mg/50 mL. For preparation of application-solution-2, used for the high dosed samples, the remaining amount of the stock-solution and application-solution-1 was combined and made up to 50 mL by addition of water. The final concentration of the test substance in application-solution-2 was 6.04 mg/50 mL.
TREATMENT PREPARATION
For the low dosed samples volumes of 760 μL (59.77 μg) of application-solution-1 were added to 200 g soil (based on the soil dry weight; 59.77 μg/200 g soil; 29.89 μg/100 g soil). For the preparation of high dosed soil samples 5 ml (0.6 mg) of application solution-2 were added to 200 g soil (based on the soil dry weight; 0.6 mg/200 g soil; 0.3 mg/100 g soil). - Soil No.:
- #1
- % Recovery:
- 100
- St. dev.:
- 2.22
- Remarks on result:
- other: mean recovery of applied radioactivity (RA) was 105.4%.
- Remarks:
- Mean and St.Dev. calculated by registrant.
- Soil No.:
- #2
- % Recovery:
- 97.8
- St. dev.:
- 5.76
- Remarks on result:
- other:
- Remarks:
- Mean and St.Dev. calculated by registrant.
- Key result
- Soil No.:
- #1
- DT50:
- 4 d
- Type:
- other: biphasic according to first-order kinetics (overall)
- Temp.:
- 20 °C
- Key result
- Soil No.:
- #2
- DT50:
- 2 d
- Type:
- other: biphasic according to first-order kinetics (overall)
- Temp.:
- 20 °C
- Soil No.:
- #1
- DT50:
- 3 d
- Type:
- other: biphasic according to first-order kinetics (fast reactions)
- Temp.:
- 20 °C
- Soil No.:
- #1
- DT50:
- 102 d
- Type:
- other: biphasic according to first-order kinetics (slow reactions)
- Temp.:
- 20 °C
- Soil No.:
- #2
- DT50:
- 1 d
- Type:
- other: biphasic according to first-order kinetics (fast reactions)
- Temp.:
- 20 °C
- Soil No.:
- #2
- DT50:
- 10 d
- Type:
- other: biphasic according to first-order kinetics (slow reactions)
- Temp.:
- 20 °C
- Transformation products:
- yes
- Details on transformation products:
- FORMATION AND DECLINE OF DEGRADATION PRODUCTS
Three major radioactive fractions were formed, i.e. M1, MB4 and MB5.
- Les Evouettes (Soil #1): In Les Evouettes soil M1 reached with 53.67% its maximum at day 14, MB4 accounted for maximally 8.79% at day 150 and MB5 was determined at a quantity of 19.9% after 90 days. Metabolites M1 and MB5 were transient metabolites representing 6.12 and 12.71% after 363 days, respectively. The amount of fraction MB4 was with 8.18% after 363 days practically unchanged. The degradation halflives (overall) of M1 and MB5 were calculated to be 74 and 389 days. All other radioactive fractions were only of minor quantity, reaching maximally 4.21% of the radioactivity applied.
- Collombey (Soil #2): In Collombey soil M1 accounted for maximally 44.97% at day 3. Radioactive fractions MB4 and MB5 reached their maxima at day 59 and 30 and amounted to 7.14 and 22.93%, respectively. At the end of the incubation time (day 363) M1, MB4 and MB5 decreased to 1.57, 3.03 and 2.54%, respectively. Fraction M1, MB4 and MB5 were transient in nature in Collombey soil, their degradation half-lives (overal[) were calculated to be 21, 335 and 78 days, respectively. Other radioactive fractions were only of minor quantity, reaching maximally 4.52% of the radioactivity applied.
PATHWAY OF DEGRADATION OF THE TEST SUBSTANCE IN SOIL UNDER AEROBIC CONDITIONS
From the structural information and the kinetic data of the present study the pathway was derived for the degradation of the test substance in soil under aerobic conditions. The test substance is degraded by hydroxylation of the methylene group in the triazine ring, leading to metabolite M1. In subsequent reactions metabolite M1 is primarily oxidized at pos. 6 of the pyridine ring leading to metabolite MB5, followed by further oxidation of the previously formed alcohol to the ketone MB4. Further degradation of M1 proceeded via cleavage of the bridge between the triazine and the pyridine ring yielding 3-pyridinecarboxaldehyde (M3). As terminal degradation products CO2 and bound residues were observed. - Evaporation of parent compound:
- no
- Volatile metabolites:
- yes
- Remarks:
- Predominantly CO2, other volatiles accounted maximally to 0.01 %
- Residues:
- yes
- Remarks:
- As terminal degradation products CO2 and bound residues were observed.
- Details on results:
- The results are tabulated in 'Any other information on results incl. tables'.
RECOVERY AND DISTRIBUTION PATTERNS OF RADIOACTIVITY
The recoveries ranged between 101.89 and 109.44% for Les Evouettes soil and between 91.38 and 111.05% for Collombey soil incubated under aerobic conditions.
- Les Evouettes (Soil #1): The extractable portion of the radioactivity (cold and Soxhlet extracts) decreased from 107.71% at day 0 to 40.11% at day 363. After cold and Soxhlet extraction selected samples were submitted to harsh extractions. Radioactivity determined in the harsh extracts was maximally 6.66% of the applied radioactivity. Non-extractable radioactivity reached 41.68% of the totally applied radioactivity after 363 days. Volatile radioactivity in form of 14CO2, resulting from the breakdown of the pyridine ring, increased to 22.17% within 363 days. Volatiles other than 14CO2 reached maximally 0.01% of the dose in a few samples.
- Collombey (Soil #2): The extractable portion of the radioactivity (cold and Soxhlet extracts) decreased from 108.95% at day 0 to 16.84% at day 363. When compared with Les Evouettes soil the latter figure was about 2.4 times lower indicating the higher biological activity of the soil. After cold and Soxhlet extraction selected samples were subjected to harsh extractions. Radioactivity determined in the harsh extracts was maximally 8.96% of the applied radioactivity. Unextractable radioactivity was slightly higher compared to Les Evouettes soil samples reaching 47.37% of the totally applied radioactivity after 363 days. Volatile radioactivity in form of 14CO2 (other volatiles accounted maximally to 0.01 %) reached with 30.55% significantly higher values than in Les Evouettes soil.
BOUND RESIDUE FRACTIONATION
Non-extractables of aerobic incubated Les Evouettes and Collombey soil after harsh extraction were further submitted to bound residue fractionation. The major radioactive fraction in both soils was the humin fraction, accounting for more than 20% of the dose applied in Les Evouettes and Collombey soil. For the latter soils, the fulvic acid fraction ranged between 6.56 and 10.05% and the humic acid fraction accounted for 2. 78 and 6. 79% of the radioactivity initially applied, respectively.
DEGRADATION OF THE TEST SUBSTANCE
The test substance was rapidly degraded in Les Evouettes and Collombey soil under aerobic conditions, reaching 363 days after treatment 3.03 and 1.03% of the dose, respectively. The rate of degradation of the test substance under aerobic conditions was faster in Collombey compared to Les Evouettes soil. Degradation half-lives of 2 and 4 days (overall degradation half-life) were determined for Collombey and Les Evouettes soil, respectively. Comparing the fast and slow degradation reactions, as calculated from the rate constants k1 and k2 of the two-compartment model, significant differences are obvious for the slow degradation reactions (described by k2): Collombey: 10 days, Les Evouettes: 102 days. The latter result may partly be due to a stronger adsorption of the test compound onto the soil, containing higher amounts of organic carbon. However, the slower degradation rate observed from about day 10 on accounted only for 20% of the dose applied thus influencing the DT-90 value of the compound in Les Evouettes soil. DT-90 values calculated were 104 and 18 days for Les Evouettes and Collombey soil, respectively. - Conclusions:
- The test substance was rapidly degraded in Les Evouettes and Collombey soils under aerobic conditions with half-lives of 4 and 2 days, respectively. The degradation pathways and the degradation products formed were equal in both systems. The dissipation of the major degradation products formed was faster in Collombey soil than in Les Evouettes soil.
- Executive summary:
The objectives of the present soil metabolism study were to provide information on the rate of degradation of the test substance, the rate of formation and decline of degradation products and the metabolism in two different soils. The study was performed in accordance with BBA Part IV, 4-1, EPA Pesticide Assessment Guidance 164-1 and Dutch Registration Guideline G.1 and was in compliance with GLP. Samples of two soils (Les Evouettes and Collombey) were treated with [5 -14C] pyridine labelled test substance at a field use rate corresponding to 0.3 kg a.i./ha (recommended field rate) and incubated under aerobic conditions in the dark at a temperature of 20±0. 7 °C. For aerobic incubation samples were taken 0, 1, 3, 7, 14,30, 59, 90, 150, 272 and 363 days after treatment.
In Les Evouettes soil the extractable portion of the radioactivity decreased from 107.71% at day 0 to 40.11% at day 363. Unextractable radioactivity reached 41.68% of the totally applied radioactivity after 363 days. Cumulative production of 14CO2, resulting from the breakdown of the pyridine ring amounted to 22.17% at the end of the incubation time. In Collombey soil the extractable portion of the radioactivity accounted for 108.95% at day 0 and decreased to 16.84% at day 363. When compared to Les Evouettes soil the latter figure was less than half of the corresponding figure. The unextractable radioactivity was slightly higher compared to Les Evouettes soil samples reaching 47.37% of the totally applied radioactivity after 363 days. 14CO2 formed during the incubation time reached 30.55%, significantly higher values than in Les Evouettes soil thus indicating a higher biological activity of Collombey soil. When non-extractables of selected soil samples were submitted to harsh (e.g. reflux under neutral and acidic conditions) procedures, between 5.10 and 8.96% of the radioactivity applied were liberated. Fractionation of the bound residue by the soil organic matter fractionation method showed that the majority of the radioactivity was associated with the humin fraction (15.5-24.6 %). In the fulvic acid and humic acid fractions 6.6-10.5% and 2.8-6.8% were found.
The test substance was rapidly degraded in Les Evouettes and Collombey soil under aerobic conditions, reaching 3.03 and 1.03% of the applied amount at the end of the study, respectively. The degradation under aerobic conditions was bi-phasic in nature. When fitted to a two-compartment model using a bi-exponential function, primary half-lives (fast reaction) observed were 3 and 1 days for Les Evouettes and Collombey soil, respectively. Thereafter, significantly slower degradation rates were observed, i.e. the corresponding half-lives were 102 and 10 days. However, the overall degradation half-life times were determined to be 4 and 2 days for Les Evouettes and Collombey soil, respectivley, while the DT-90 values in the corresponding soils were 104 and 18 days.
The test substance was degraded by hydroxylation of the methylene group in the triazine ring, leading to the alcohol M1, which was the major metabolite formed. It accounted after 14 and 3 days at maximum for 53.67 and 44.97% in Les Evouettes and Collombey soil, respectively. The latter metabolite was transient in nature and decreased after 363 days to 6.12 and 1.57% in Les Evouettes and Collombey soil, respectively. Its overall degradation half-life was determined to be 74 and 21 days in Les Evouettes and Collombey soil, respectively. In subsequent reactions metabolite M1 was primarily oxidized at pos. 6 of the pyridine ring forming metabolite MB5 as a further transient metabolite, degrading with half-lives of 389 and 78 days in Les Evouettes and Collombey soil, respectively. In following reactions MB5 was further oxidized to the ketone metabolite MB4. Metabolite MB4 reached with 8.79-8.18 % after 150 to 363 days an apparent plateau in Les Evouettes soil. In Collombey soil MB4 reached its highest concentration with 7.14 % after 59 days. At the end of the study its amount was 3.03 %. Its calculated half-life in the latter soil was 335 days. As minor pathway the degradation of metabolite M1 into metabolite M3 was observed. Finally the formation of CO2 and bound residues was observed.
- Endpoint:
- biodegradation in soil: simulation testing
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 13 Nov 2009 to 01 Nov 2011
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)
- Version / remarks:
- April 2002
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- other: EC Directive 95/36/EC, Active Substances, Section 7.1.1 (July 1995) European Community Commission Directive 95/36/EC of July 14 1995, Amending Council Directive 91/414/EEC: 7.1.1.1 Aerobic Degradation (Route Study) and 7.1.1.2.1 Laboratory Studies (Rate)
- Version / remarks:
- July 1995
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- other: SETAC-EUROPE Procedures for Assessing the Environmental Fate and Ecotoxicity of Pesticides: Section 1.1 (Laboratory Aerobic Soil Degradation Studies)
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Test type:
- laboratory
- Radiolabelling:
- yes
- Remarks:
- [14C]-labelled at either position 6 of the triazine ring or position 5 of the pyridine ring
- Oxygen conditions:
- aerobic
- Soil classification:
- USDA (US Department of Agriculture)
- Year:
- 2 009
- Soil type:
- sandy clay loam
- % Clay:
- 25
- % Silt:
- 24
- % Sand:
- 51
- % Org. C:
- 2.5
- pH:
- >= 6.1 - <= 6.9
- CEC:
- 18.9 meq/100 g soil d.w.
- Bulk density (g/cm³):
- 1.5
- Details on soil characteristics:
- A detailed overview of the soil characteristics is presented in 'Any other information on materials and methods incl. tables'.
Soil preparation: the soil was sieved (2 mm mesh) with theminimum of air-drying and was stored in loosely tied plastic bags in an incubator routinely maintained at 4 ± 2°C. Aliquots of the sieved soil were taken and air-dried for determination of physico-chemical characteristics. - Duration:
- 120 d
- Initial conc.:
- 0.8 mg/kg soil d.w.
- Based on:
- act. ingr.
- Remarks:
- equivalent to a single field application rate of 600 g ai/ha, incorporated into the soil to a depth of 5 cm and assuming a soil bulk density of 1.5 g/cm3.
- Temp.:
- 20 ± 1 °C
- Humidity:
- Soils were adjusted to pF2 moisture tension (29.8%)
- Microbial biomass:
- The quantity of microbial biomass carbon constituted 3.9% at the time of treatment. At the end of the 120 DAT incubation period the microbial biomass carbon constituted a minimum 1.8% of soil organic carbon.
- Details on experimental conditions:
- EXPERIMENTAL DESIGN
- Stock preparation: A stock solution of [pyridinyl-14C]- and [triazinyl-14C]-test substance in methanol were prepared. The prepared stock solutions had a concentration of 0.768 and 0.645 mg/mL by liquid scintillation counting (LSC) assay, respectively. The radiochemical purity of test item in the stock solutions were ≥ 98% and ≥ 99% by HPLC, respectively.
- Soil condition: Fresh
- Soil (g/replicate): 100 g (dry weight) per replicate
- Number of replicates: 2
- Test apparatus: Glass flask, moist air flow through system, connections made with glass and PVC tubing
- Details of traps for CO2 and organic volatile, if any: Volatile products produced were trapped using a flow-through system. Air was pulled (using a vacuum pump) through a water trap, then through the incubation vessel and any volatiles were collected in outlet 2M sodium hydroxide traps. At each sampling interval the traps associated with the sampled vessels were removed and quantified by LSC. Additionally traps were analysed and replenished with fresh reagents at intervals up to 40 days.
- Confirmation of carbon dioxide in sodium hydroxide traps: The nature of the radioactivity trapped in the sodium hydroxide traps was investigated by addition of barium chloride solution. Analyses were performed on traps associated with a single unit from the 120 DAT timepoint for each of the two incubation groups. A saturated solution of barium chloride in water (8 mL) was added to a sub-sample (4 mL) of the pooled traps and mixed. Only the first of the sodium hydroxide traps was used because
there was no radioactivity in second trap. The sample was allowed to stand for at least 1 hour, centrifuged (2000 g, 10 minutes) and the radioactivity in the supernatant was determined by LSC. Any dissolved 14CO2 present precipitated as insoluble barium [14C]-carbonate during this process. - % Recovery:
- 96.4
- St. dev.:
- 1.55
- Remarks on result:
- other: [Pyridinyl-14C]-test substance recovery
- Remarks:
- Mean % Recovery and St.Dev calculated by registrant
- % Recovery:
- 95.4
- St. dev.:
- 3.3
- Remarks on result:
- other: [Triazinyl-14C]-test substance recovery
- Remarks:
- Mean % Recovery and St.Dev calculated by registrant
- Key result
- DT50:
- 5 d
- Type:
- (pseudo-)first order (= half-life)
- Temp.:
- 20 °C
- Remarks on result:
- other: both labels
- Transformation products:
- yes
- Details on transformation products:
- [Pyridinyl-14C]-test substance degradation
Levels of parent compound decreased quickly over the 120 day incubation period from an initial value of 85.9% to 5.0% AR at 24 DAT, this decreased further to 0.6% AR at the end of the incubation period. In addition to parent, four metabolites were identified and present at ≥ 5% AR. M3, M1, M4 and M7 were present at up to 14.4% (2 DAT), 11.4% (5 DAT), 13.0% (10 DAT) and 13.7% AR (15, 24 DAT), respectively, before decreasing to ≤ 1% AR by the end of the incubation period.
[Triazinyl-14C]-test substance degradation
Levels of parent compound decreased quickly over the 120 day incubation period from an initial value of 89.4% to 5.9% AR at 24 DAT, this decreased further to 0.6% AR at the end of the incubation period. In addition to parenttwo metabolites were identified and present at ≥ 10% AR. M1 and M4 were present at up to 13.8% (5 DAT) and 12.0% AR (15 DAT), respectively.
Verification of metabolites by a second technique (TLC) was performed using reference standards. Parent and metabolites were confirmed using 1D-TLC and 2D-TLC methods. - Evaporation of parent compound:
- no
- Volatile metabolites:
- yes
- Remarks:
- see 'Details on results'
- Residues:
- yes
- Remarks:
- see 'Details on results'
- Details on results:
- MICROBIAL BIOMASS
The quantity of microbial biomass carbon constituted 3.9% at the time of treatment. At the end of the 120 DAT incubation period the microbial biomass carbon constituted a minimum 1.8% of soil organic carbon. This indicated the soil supported a viable microbial population and that the soil was suitable for use in a laboratory degradation study.
APPLICATION RATE
The amount of [14C]-test substance applied to each soil vessel was determined by LSC quantification of the treatment solution at the time of application. The final soil concentrations achieved were 80.7 μg/100g and 82.9 μg/100g for [pyridinyl-14C]-test substance and [triazinyl-14C]-test substance, respectively, (equivalent to a field application rate of 605 and 622 g ai/ha, respectively). The radioactivity added to each unit was 173.9 and 190.1 kBq for [pyridinyl-14C]-test substance and [triazinyl-14C]-test substance, respectively. The application solution was shown to be homogeneous throughout each application, with coefficient of variation between the pre-and post- application homogeneity checks being a maximum of 2.3%.
RADIOACTIVE RESIDUES IN SOIL EXTRACTS
The total extractability at 0 DAT was high (ranging from 93.9 to 98.8% AR) and decreased to 4.0% (pyridinyl label) and 12.0% (triazinyl label) at 120 DAT. A further 4.2 and 8.3% AR
was recovered in additional soil extracts and a reflux extract in a single sample treated with [triazinyl-14C]-test substance at 120 DAT using harsh extraction conditions.
UNEXTRACTED RADIOACTIVITY
Unextracted radioactivity increased from 3.9 to 4.4% AR at 0 DAT to reach maximum levels of 26.8% AR (pyridinyl, 24 DAT) and 52.7% AR (triazinyl, 80 DAT) before decreasing to 19.6 to 43.3% AR at 120 DAT. Further characterisation of the unextracted soil residue was carried out on a single 120 DAT soil sample from each incubation group. An extraction was undertaken which separated the natural organic matter present in soil into three fractions: fulvic acids (soluble in both acid and alkali), humic acids (soluble in alkali but insoluble in acid) and humin (insoluble in both acid and alkali). Radioactivity was recovered from all three fractions indicating progressive assimilation and metabolism of the test compound within the soil organic matter fractions.
VOLATILE DEGRADATION PRODUCTS
Significant levels of volatile radioactivity were formed during the incubation period increasing to 72.8% (pyridinyl label) and 30.9% AR (triazinyl label) at 120 DAT. Carbon dioxide was proven in each incubation group by barium carbonate precipitation of the radioactivity from a pooled sample of the traps following addition of barium chloride solution. - Conclusions:
- The route and rate of degradation of [14C]-test substance was investigated in one soil, 18 Acres. The test substance degraded rapidly in 18 Acres soil. The DegT50 and DegT90 values using single first-order kinetics were 5 and 16 days, respectively.
- Executive summary:
STUDY DESIGN
The rate and route of degradation of [pyridinyl-14C]-test substance and [triazinyl-14C]-test substance was investigated in 18 Acres soil. [Pyridinyl-14C]-test substance and [triazinyl-14C]-test substance were applied at a nominal rate of 0.8 mg/kg dry weight of soil, which is equivalent to a single field application rate of 600 g ai/ha, incorporated into the soil to a depth of 5 cm and assuming a soil bulk density of 1.5 g/cm3. The soil samples were incubated under aerobic conditions in the laboratory and maintained under moist (approximately pF2), dark conditions at 20 ± 1°C for up to 120 days. Duplicate samples were taken for analysis at 0, 6, 12 hours, 1, 2, 5, 10, 15, 24, 50, 80 and 120 days after treatment (DAT). At each sampling time, samples were analysed for extractable parent compound, degradation products and unextracted residues. Any volatile radioactivity was continuously flushed from the vessels and collected in liquid traps. A mass balance was determined for each sample.
CONCLUSIONS
The route and rate of degradation of [14C]-test substance was investigated in one soil, 18 Acres. The test substance degraded rapidly in 18 Acres soil. The DegT50 and DegT90 values using single first-order kinetics were 5 and 16 days, respectively. Eight metabolites were present in the total extracts at ≥ 5% of applied radioactivity for two or more timepoints. M3, M1, M4 and M7 were present at up to 14.4%, 13.8%, 13.0% and 13.7% AR, respectively. Significant portions of applied radioactivity 72.8 and 30.9% were evolved as carbon dioxide during the 120 day incubation period for samples treated with [pyridinyl-14C]-test substance and [triazinyl-14C]-test substance, respectively. Levels of radioactivity in unextracted residues reached maximum levels of 19.6 and 43.3% for [pyridinyl-14C]-test substance and [triazinyl-14C]-test substance, respectively. The mass balances were between 92.2 and 102.7% AR throughout the incubation period.
Referenceopen allclose all
Table: Distribution Pattern of Radioactivity for the Degradation of the test substance in Les Evouettes Soil under Aerobic Conditions (Values are given in % of the radioactivity applied)
Incubation Time [days] |
Radioactive fraction |
Recovery |
|||
CO2 |
Volatiles |
Extractables |
Non-extractables |
||
0 |
DL |
DL |
101.6 |
1.6 |
103.2 |
1 |
≤0.2 |
DL |
91.1 |
15.0 |
106.2 |
3 |
0.2 |
DL |
95.6 |
10.7 |
106.5 |
7 |
0.8 |
DL |
87.5 |
17.0 |
105.3 |
14 |
1.0 |
DL |
77.2 |
21.2 |
99.4 |
29 |
1.9 |
DL |
66.6 |
31.6 |
100.1 |
61 |
4.0 |
DL |
52.4 |
37.8 |
94.2 |
90 |
2.8 |
DL |
45.8 |
41.5 |
90.1 |
180 |
13.4 |
DL |
31.8 |
45.3 |
90.5 |
239 |
17.9 |
DL |
26.8 |
46.5 |
91.2 |
361 |
23.6 |
DL |
18.8 |
50.6 |
93.0 |
Detection limit (DL) = 0.1%
Table: Distribution Pattern of Radioactivity for the Degradation of the test substance in Collombey Soil under Aerobic Conditions (Values are given in % of the radioactivity applied)
Incubation Time [days] |
Radioactive fraction |
Recovery |
|||
CO2 |
Volatiles |
Extractables |
Non-extractables |
||
0 |
DL |
DL |
103.9 |
1.2 |
105.0 |
1 |
≤0.2 |
DL |
94.1 |
8.1 |
102.3 |
3 |
0.3 |
DL |
92.4 |
9.7 |
102.4 |
7 |
0.4 |
DL |
87.1 |
15.1 |
102.6 |
14 |
0.3 |
DL |
77.2 |
21.3 |
98.7 |
29 |
2.4 |
DL |
62.3 |
27.2 |
91.9 |
61 |
4.6 |
DL |
41.9 |
45.6 |
92.1 |
90 |
8.1 |
DL |
32.7 |
53.0 |
93.8 |
180 |
18.5 |
DL |
17.5 |
59.7 |
95.7 |
239 |
25.0 |
DL |
11.9 |
62.2 |
99.1 |
361 |
30.0 |
DL |
5.8 |
63.7 |
99.5 |
Detection limit (DL) = 0.1%
Table: Distribution Pattern of Radioactivity for the Degradation of the test substance in Les Evouettes Soil under 10 Days of Aerobic and 91 Days of Anaerobic Conditions
Incubation Time [days] |
Radioactive fraction |
Recovery |
|||
CO2 |
Volatiles |
Extractables |
Non-extractables |
||
-10 (aerobic) |
DL |
DL |
102.6 |
1.9 |
104.4 |
0 |
1.2 |
DL |
86.2 |
20.1 |
107.5 |
30 |
0.8 |
DL |
70.4 |
24.0 |
95.2 |
60 |
2.0 |
DL |
68.3 |
32.5 |
102.8 |
91 |
2.4 |
DL |
62.2 |
35.1 |
99.7 |
Detection limit (DL) = 0.1%
Table: Distribution Pattern of Radioactivity for the Degradation of the test substance in Collombey under 10 Days of Aerobic and 91 Days of Anaerobic Conditions
Incubation Time [days] |
Radioactive fraction |
Recovery |
|||
CO2 |
Volatiles |
Extractables |
Non-extractables |
||
-10 (aerobic) |
DL |
DL |
103.3 |
1.1 |
104.4 |
0 |
1.6 |
DL |
85.6 |
17.6 |
104.8 |
30 |
2.1 |
DL |
70.2 |
23.4 |
95.7 |
60 |
2.4 |
DL |
60.8 |
28.6 |
91.8 |
91 |
2.5 |
DL |
55.1 |
51.0 |
108.6 |
Detection limit (DL) = 0.1%
Table: Distribution Pattern of Radioactivity for the Degradation of the test substance in Les Evouettes Soil under Aerobic/Sterile Conditions
Incubation Time [days] |
Radioactive fraction |
Recovery |
|||
CO2 |
Volatiles |
Extractables |
Non-extractables |
||
0 |
DL |
DL |
108.2 |
1.1 |
109.3 |
29 |
0.3 |
DL |
84.7 |
14.8 |
99.8 |
61 |
0.4 |
DL |
77.9 |
21.7 |
100.0 |
90 |
1.0 |
DL |
68.7 |
29.7 |
99.5 |
Detection limit (DL) = 0.1%
Table: Harsh Extraction Of Bound Residue
|
Sample |
||||
A |
B |
C |
D |
E |
|
Non-Extractables after Soxhlet Extraction |
50.6 |
63.7 |
35.1 |
51.0 |
29.7 |
Acetonitrile:Water, reflux |
2.6 |
1.1 |
2.5 |
3.0 |
3.1 |
Acetonitrile:Water pH<2, reflux |
1.7 |
0.7 |
0.8 |
1.0 |
0.8 |
Total Harsh Extract |
4.2 |
1.8 |
3.2 |
4.0 |
3.9 |
Remaining Bound Residue |
46.4 |
61.9 |
31.9 |
47.0 |
25.8 |
Samples A: Les Evouettes, aerobic incubation day 361,
Samples B: Collombey aerobic incubationday 361,
Samples C: Les Evouettes, aerobic/anaerobic incubation day 101,
Samples D: Collombey aerobic / anaerobic incubation day 101,
Samples E: Les Evouettes, aerobic / sterile incubation day 90
Table: Fractionation of Humic Substance (Values arc given in% of the radioactivity applied)
|
Sample |
|
Les Evouettes |
Collombey |
|
Non-Extractables after Harsh Extraction |
46.4 |
61.9 |
Fulvic Acid |
1.4 |
1.4 |
Humic Acid |
0.2 |
0.2 |
Humin |
44.8 |
60.3 |
Total |
46.4 |
61.9 |
Table: Degradation rate of the test substance and metabolites in Les Evouettes Soil Under Aerobic Conditions
Constant |
Parent |
M1 |
UM3 |
M2 |
Model |
Two Comp. |
One Comp. |
One Comp. |
One Comp. |
r-squared |
0.99837 |
0.79025 |
0.96651 |
0.90426 |
Chi-squared |
2.83488 |
11.65083 |
3.96378 |
1.88757 |
C01 |
70.71 |
19.97 |
25.33 |
11.71 |
K1 |
0.38288 |
0.00565 |
0.01528 |
0.00238 |
C02 |
30.09 |
- |
- |
- |
K2 |
0.03713 |
- |
- |
- |
DT50 [d] |
2.9 |
122.7 |
45.4 |
291.2 |
DT90 [d] |
29 |
408 |
151 |
967 |
UM - unknown metabolite
Table: Degradation Rate of the test substance and Metabolites in Les Evouettes Soil under Aerobic/Anaerobic Conditions
Constant |
Parent |
M1 |
M8 |
M2 |
Model |
Two Comp. |
One Comp. |
One Comp. |
One Comp. |
r-squared |
0.99923 |
0.99061 |
0.95344 |
0.98031 |
Chi-squared |
1.33242 |
0.82071 |
0.64826 |
1.86417 |
C01 |
61.65 |
22.92 |
9.82 |
22.96 |
K1 |
0.56749 |
0.05631 |
0.00546 |
0.01 |
C02 |
40.50 |
- |
- |
- |
K2 |
0.07735 |
- |
- |
- |
DT50 [d] |
2.3 |
12.3 |
127.0 |
62.1 |
DT90 [d] |
18 |
41 |
422 |
206 |
UM - unknown metabolite
Table: Degradation Rate of the test substance and Metabolites in Collombey Soil under Aerobic/Anaerobic Conditions
Constant |
Parent |
M1 |
Model |
One Comp. |
One Comp. |
r-squared |
0.48949 |
0.81218 |
Chi-squared |
4.56910 |
44.46091 |
C01 |
26.66 |
38.48 |
K1 |
0.00182 |
0.00905 |
C02 |
- |
- |
K2 |
- |
- |
DT50 [d] |
380.9 |
76.6 |
DT90 [d] |
n.d. |
254 |
Table: Regression Output for the Degradation of the test substance and Metabolites in Les Evouettes Soil under Aerobic/Sterile Conditions
Constant |
Parent |
M1 |
UM3 |
M2 |
Model |
One Comp. |
One Comp. |
One Comp. |
One Comp. |
r-squared |
0.06703 |
0.99182 |
0.95921 |
0.89908 |
Chi-squared |
12.71054 |
027556 |
1.27924 |
4.15932 |
C01 |
22.23 |
20.55 |
13.2613.26 |
15.04 |
K1 |
0.00098 |
0.00847 |
0.01771 |
0.01 |
C02 |
- |
- |
- |
- |
K2 |
- |
- |
- |
- |
DT50 [d] |
707.3 |
81.8 |
39.1 |
50.0 |
DT90 [d] |
n.d. |
272 |
130 |
166 |
UM - unknown metabolite
Table: Regression Output for the Degradation of test substance and Metabolites in Les Evouettes soil under Aerobic/Sterile Conditions
Constant |
Parent |
Model |
One Comp. |
r-squared |
0.96564 |
Chi-squared |
76.64371 |
C01 |
105.09 |
K1 |
0.02099 |
C02 |
- |
K2 |
- |
DT50 [d] |
33.0 |
DT90 [d] |
110 |
Table: Extraction and recovery of radioactivity from Les Evouettes silt loam soil after application of the radiolabelled test substance at a rate of 1.0 mg/kg (results are expressed in % applied radioactivity).
Time after application (days) |
Sample number |
Storage column |
Extracted |
Not extracted |
Volatiles |
Total recovery |
|||
Acetone/ water |
Water |
Acetone (Soxhlet) |
Totalextracted |
||||||
0 0 |
9 16 |
- - |
95.5 94.1 |
- - |
- - |
95.5 94.1 |
2.9 2.6 |
- - |
98.4 96.7 |
3 |
6 |
A |
80.9 |
2.8 |
6.6 |
90.3 |
6.9 |
0.1 |
97.3 |
3 |
7 |
A |
79.2 |
2.5 |
6.1 |
87.8 |
6.2 |
0.1 |
94.1 |
7 |
10 |
A |
70.7 |
2.9 |
0.6 |
74.2 |
11.5 |
0.5 |
86.2 |
7 |
20 |
A |
71.3 |
2.8 |
9.3 |
83.4 |
11.7 |
0.5 |
95.6 |
14 |
11 |
A |
62.8 |
0.9 |
6.4 |
70.1 |
17.5 |
1.9 |
89.5 |
14 |
18 |
A |
62.4 |
1.0 |
9.0 |
72.4 |
18.4 |
1.9 |
92.7 |
33 |
4 |
A |
42.7 |
3.0 |
9.2 |
54.9 |
33.0 |
5.9 |
93.8 |
33 |
15 |
A |
42.9 |
3.4 |
10.6 |
56.9 |
35.5 |
5.9 |
98.3 |
60 |
1 |
A |
32.4 |
2.2 |
8.3 |
42.9 |
40.2 |
10.9 |
94.0 |
60 |
13 |
A |
31.9 |
2.3 |
8.6 |
42.8 |
42.5 |
10.9 |
96.2 |
90 |
14 |
B |
23.2 |
1.9 |
8.2 |
33.3 |
52.7 |
14.5 |
100.5 |
90 |
21 |
B |
23.3 |
2.0 |
7.7 |
33.0 |
44.4 |
14.5 |
91.9 |
122 |
8 |
B |
18.4 |
1.2 |
6.8 |
26.4 |
50.5 |
18.5 |
95.4 |
122 |
17 |
B |
20.7 |
1.3 |
8.9 |
30.9 |
44.6 |
18.5 |
94.0 |
Table: Extraction and recovery of radioactivity from Collombey loamy sand soil after application of the radiolabelled test substance at a rate of 1.0 mg/kg (results are expressed in % applied radioactivity).
Time after application (days) |
Sample number |
Storage column |
Extracted |
Not extracted |
Volatiles |
Total recovery |
|||
Acetone/ water |
Water |
Acetone (Soxhlet) |
Total extracted |
||||||
0 |
28 |
- |
98.2 |
- |
- |
98.2 |
1.0 |
- |
99.2 |
0 |
41 |
- |
95.6 |
- |
- |
95.6 |
1.5 |
- |
97.1 |
3 |
34 |
C |
86.2 |
1.7 |
3.4 |
91.3 |
5.5 |
0.1 |
96.9 |
3 |
40 |
C |
88.2 |
1.6 |
4.0 |
93.8 |
4.5 |
0.1 |
98.4 |
7 |
27 |
C |
74.8 |
2.0 |
4.4 |
81.2 |
11.4 |
0.6 |
93.2 |
7 |
37 |
C |
78.8 |
1.9 |
5.0 |
85.7 |
11.1 |
0.6 |
97.4 |
14 |
35 |
C |
67.4 |
1.0 |
4.9 |
73.3 |
19.3 |
1.7 |
94.3 |
14 |
44 |
C |
66.4 |
1.1 |
5.7 |
73.2 |
18.5 |
1.7 |
93.4 |
33 |
30 |
C |
43.9 |
3.6 |
5.3 |
52.8 |
36.0 |
5.4 |
94.2 |
33 |
33 |
C |
45.9 |
3.7 |
5.9 |
55.5 |
30.9 |
5.4 |
91.8 |
60 |
25 |
C |
28.0 |
3.1 |
4.3 |
35.4 |
46.0 |
10.8 |
92.2 |
60 |
29 |
C |
28.8 |
2.9 |
4.1 |
35.8 |
45.7 |
10.8 |
92.3 |
90 |
23 |
D |
19.9 |
2.5 |
5.4 |
27.8 |
48.6 |
14.7 |
91.1 |
90 |
36 |
D |
20.1 |
2.6 |
4.8 |
27.5 |
46.4 |
14.7 |
88.6 |
122 |
31 |
D |
13.9 |
1.3 |
4.4 |
19.6 |
52.0 |
18.8 |
90.4 |
122 |
38 |
D |
14.l |
1.2 |
4.6 |
19.9 |
51.1 |
18.8 |
89.8 |
Table: Extraction and recovery of radioactivity from Speyer 2.2 sand soil after application of the radiolabelled test substance at a rate of 1.0 mg/kg (results are expressed in % applied radioactivity).
Time after application (days) |
Sample number |
Storage column |
Extracted |
Not extracted |
Volatiles |
Total recovery |
|||
Acetone/ water |
Water |
Acetone (Soxhlet) |
Total extracted |
||||||
0 0 |
48 63 |
- - |
94.7 95.4 |
- - |
- - |
94.7 95.4 |
3.2 2.9 |
- - |
97.9 98.3 |
3 |
55 |
E |
76.2 |
2.9 |
11.2 |
90.3 |
5.4 |
0.1 |
95.8 |
3 |
56 |
E |
80.8 |
2.7 |
9.9 |
93.4 |
5.4 |
0.1 |
98.9 |
7 |
59 |
E |
74.8 |
2.8 |
12.8 |
90.4 |
7.7 |
0.3 |
98.4 |
7 |
66 |
E |
71.4 |
3.0 |
12.7 |
87.1 |
8.6 |
0.3 |
96.0 |
14 14 |
61 64 |
E E |
65.8 65.3 |
0.8 0.8 |
10.8 10.6 |
77.4 76.7 |
17.0 15.6 |
0.8 0.8 |
95.2 93.1 |
33 33 |
45 52 |
E E |
50.7 52.9 |
3.5 3.4 |
14.3 13.3 |
68.5 69.6 |
23.7 23.5 |
2.6 2.6 |
94.8 95.7 |
60 60 |
47 50 |
E E |
46.0 44.7 |
2.1 2.1 |
9.8 12.8 |
57.9 59.6 |
31.9 30.1 |
5.6 5.6 |
95.4 95.3 |
90 90 |
62 65 |
F F |
37.5 36.0 |
2.1 1.9 |
12.3 13.6 |
51.9 51.5 |
37.3 35.0 |
8.5 8.5 |
97.7 95.0 |
122 |
46 |
F |
30.5 |
1.2 |
11.0 |
42.7 |
40.5 |
11.4 |
94.6 |
122 |
53 |
F |
30.4 |
1.3 |
9.8 |
41.5 |
43.3 |
11.4 |
96.2 |
180 |
49 |
F |
20.6 |
2.0 |
10.0 |
32.6 |
46.1 |
16.3 |
95.0 |
180 |
60 |
F |
21.1 |
2.1 |
10.6 |
33.8 |
47.8 |
16.3 |
97.9 |
Table: Production of volatile radioactivity from Les Evouettes silt loam soil after application of the radiolabelled test substance at a rate of 1.0 mg/kg (results expressed as % applied radioactivity)
Time interval (days) |
Storage column |
Number of soils contributing |
Trap 2 % |
Cumulative total volatiles % |
0 - 3 |
A |
10 |
0.07 |
0.07 |
B |
10 |
0.18 |
0.18 |
|
3 - 7 |
A |
8 |
0.43 |
0.50 |
B |
10 |
0.45 |
0.63 |
|
7 - 14 |
A |
6 |
1.35 |
1.85 |
B |
10 |
1.16 |
1.79 |
|
14 - 21 |
A |
4 |
1.53 |
3.38 |
B |
10 |
1.29 |
3.08 |
|
21 - 33 |
A |
4 |
2.50 |
5.88 |
B |
10 |
2.22 |
5.30 |
|
33 - 45 |
A |
2 |
2.38 |
8.26 |
B |
10 |
2.28 |
7.58 |
|
45 - 60 |
A |
2 |
2.65 |
10.91 |
B |
10 |
2.51 |
10.09 |
|
60 - 75 |
B |
10 |
2.33 |
12.42 |
75 - 90 |
B |
10 |
2.06 |
14.48 |
90 - 105 |
B |
8 |
1.99 |
16.47 |
105 - 122 |
B |
8 |
2.07 |
18.54 |
The quantity of radioactivity in each of these trapping media was below the limit of accurate determination. This varied from 0.002 to 0.04% applied radioactivity depending on the trapping medium and the number of soils contributing.
Table: Production of volatile radioactivity from Collombey loamy sand soil after application of the radiolabelled test substance at a rate of 1.0 mg/kg (results expressed as % applied radioactivity)
Time interval (days) |
Storage column |
Number of soils contributing |
Trap 2 % |
Cumulative total volatiles % |
0-3 |
C |
10 |
0.11 |
0.11 |
D |
10 |
0.15 |
0.15 |
|
3 - 7 |
C |
8 |
0.44 |
0.55 |
D |
10 |
0.38 |
0.53 |
|
7 - 14 |
C |
6 |
1.12 |
1.67 |
D |
10 |
0.90 |
1.43 |
|
14 - 21 |
C |
4 |
1.29 |
2.96 |
D |
10 |
1.22 |
2.65 |
|
21 - 33 |
C |
4 |
2.47 |
5.43 |
D |
10 |
2.51 |
5.16 |
|
33 - 45 |
C |
2 |
2.51 |
7.94 |
D |
10 |
2.36 |
7.52 |
|
45 - 60 |
C |
2 |
2.83 |
10.77 |
D |
10 |
1.87 |
9.39 |
|
60 - 75 |
D |
10 |
2.96 |
12.35 |
75 - 90 |
D |
10 |
2.37 |
14.72 |
90 - 105 |
D |
8 |
2.11 |
16.83 |
105 - 122 |
D |
8 |
1.97 |
18.80 |
The quantity of radioactivity in each of these trapping media was below the limit of accurate determination. This varied from 0.002 to 0.04% applied radioactivity depending on the trapping medium and the number of soils contributing.
Table: Production of volatile radioactivity from Speyer 2.2 sand soil after application of the radiolabelled test substance at a rate of 1.0 mg/kg (results expressed as % applied radioactivity)
Time interval (days) |
Storage column |
Number of soils contributing |
Trap 2 % |
Cumulative total volatiles % |
0 - 3 |
E |
10 |
0.11 |
0.11 |
F |
10 |
0.11 |
0.11 |
|
3 - 7 |
E |
8 |
0.20 |
0.31 |
F |
10 |
0.22 |
0.33 |
|
7 - 14 |
E |
6 |
0.50 |
0.81 |
F |
10 |
0.51 |
0.84 |
|
14 - 21 |
E |
4 |
0.62 |
1.43 |
F |
10 |
0.61 |
1.45 |
|
21 - 33 |
E |
4 |
1.15 |
2.58 |
F |
10 |
1.14 |
2.59 |
|
33 - 45 |
E |
2 |
1.36 |
3.94 |
F |
10 |
1.26 |
3.85 |
|
45 - 60 |
E |
2 |
1.70 |
5.64 |
F |
10 |
1.57 |
5.42 |
|
60 - 75 |
F |
10 |
1.58 |
7.00 |
75 - 90 |
F |
10 |
1.50 |
8.50 |
90 - 105 |
F |
8 |
1.48 |
9.98 |
105 - 122 |
F |
8 |
1.46 |
11.44 |
122 - 136 |
F |
6 |
1.27 |
12.71 |
136 - 151 |
F |
6 |
1.29 |
14.00 |
151 - 164 |
F |
6 |
1.06 |
15.06 |
164 - 180 |
F |
6 |
1.24 |
16.30 |
The quantity of radioactivity in each of these trapping media was below the limit of accurate determination. This varied from 0.002 to 0.04% applied radioactivity depending on the trapping medium and the number of soils contributing.
Table: Measurements of the microbial biomass in the test soils. Results are expressed as mg microbial carbon/100 g dry weight soil
Time after test substance application (days) |
Les Evouettes silt loam |
Collombey loamy sand |
Speyer 2.2 sand |
-2 |
93 |
96 |
34 |
193 |
42 |
59 |
34 |
Table: Proportions of the test substance remaining in extracts of Les Evouettes silt loam soil. Results are expressed as % applied radioactivity.
Time after application(days) |
Sample number |
Test substance % |
(mean) |
0 |
9 16 |
91.3 90.2 |
(90.8) |
3 |
6 7 |
57.3 56.1 |
(56.7) |
7 |
10 20 |
37.7 29.6 |
(33.7) |
14 |
11 18 |
17.3 22.7 |
(20.0) |
33 |
4 15 |
6.2 6.4 |
(6.3) |
60 |
1 13 |
2.7 3.0 |
(2.9) |
90 |
14 21 |
1.8 1.7 |
(1.8) |
122 |
8 17 |
1.3 1.4 |
(1.4) |
Table: Proportions of the test substance remaining in extracts of Collombey loamy sand soil. Results are expressed as % applied radioactivity.
Time after application (days) |
Sample number |
Test substance % |
(mean) |
0 |
28 41 |
94.0 90.4 |
(92.2) |
3 |
34 40 |
63.5 65.9 |
(64.7) |
7 |
27 37 |
26.5 32.1 |
(29.3) |
14 |
35 44 |
14.9 14.1 |
(14.5) |
33 |
30 33 |
4.1 5.4 |
(4.8) |
60 |
25 29 |
1.3 1.3 |
(1.3) |
90 |
23 36 |
0.6 0.9 |
(0.8) |
122 |
31 38 |
0.4 0.5 |
(0.5) |
Table: Proportions of the test substance remaining in extracts of Speyer 2.2 sand soil. Results are expressed as % applied radioactivity.
Time after application (days) |
Sample number |
Test substance % |
(mean) |
0 |
48 63 |
90.3 90.8 |
(90.6) |
3 |
55 56 |
74.0 77.6 |
(75.8) |
7 |
59 66 |
70.9 63.9 |
(67.4) |
14 |
61 64 |
53.4 49.8 |
(51.6) |
33 |
45 52 |
33.6 37.0 |
(35.3) |
60 |
47 50 |
20.7 22.2 |
(21.5) |
90 |
62 65 |
14.1 18.4 |
(16.3) |
122 |
46 53 |
9.1 8.2 |
(8.7) |
180 |
49 60 |
4.7 5.1 |
(4.9) |
Table: DT50 and DT90 values for the test substance and DT50 values for metabolite M1 in the test soils
Substance |
Soil |
DT50 (days) |
DT90 (days) |
Rate constant (per day) |
Chi2 |
Test substance |
Les Evouettes silt loam |
5.4 |
18.1 |
0.12731 |
16.24594 |
Collombey loamy sand |
4.8 |
16.1 |
0.14327 |
10.87897 |
|
Speyer 2.2 sand |
29.1 |
96.6 |
0.02383 |
29.73514 |
|
M1 |
Les Evouettes silt loam |
43.1 |
- |
0.01609 |
0.46557 |
Collombey loamy sand |
20.8 |
- |
0.03329 |
1.44500 |
|
Speyer 2. 2 sand |
66.0 |
- |
0.01051 |
0.60893 |
Table: Mean Distribution of Radioactivity during Degradation of [5-14C] Pyridine-ring labelled test substance in Les Evouettes Soil under Aerobic Conditions
Time |
Volatiles |
Vol. Total |
Extractable |
Non-Extractable |
Total Recovery |
|||
NaOH |
H2SO4 |
|
Cold |
Soxhlet |
Total |
|||
[% Radioactivity applied] |
||||||||
0 |
0.00 |
0.00 |
0.00 |
103.54 |
4.16 |
107.71 |
1.74 |
109.44 |
1 |
0.09 |
0.00 |
0.09 |
91.32 |
6.52 |
97.84 |
5.30 |
103.23 |
3 |
0.21 |
0.00 |
0.21 |
83.36 |
12.16 |
95.52 |
8.37 |
104.09 |
7 |
0.47 |
0.00 |
0.47 |
76.84 |
16.92 |
93.76 |
11.30 |
105.53 |
14 |
1.07 |
0.00 |
1.07 |
68.16 |
23.19 |
91.35 |
13.09 |
105.50 |
30 |
2.41 |
0.00 |
2.41 |
57.11 |
30.30 |
87.42 |
16.28 |
106.11 |
59 |
4.98 |
0.00 |
4.98 |
47.86 |
22.92 |
70.79 |
30.91 |
106.67 |
90 |
7.23 |
0.01 |
7.24 |
42.84 |
26.71 |
69.56 |
31.68 |
108.48 |
150 |
10.23 |
0.00 |
10.23 |
31.71 |
29.94 |
61.65 |
32.64 |
104.52 |
272 |
17.87 |
0.01 |
17.87 |
21.28 |
21.80 |
43.09 |
40.93 |
101.89 |
363 |
22.17 |
0.00 |
22.17 |
21.07 |
19.05 |
40.11 |
41.68 |
103.96 |
Table: Distribution of Radioactivity during Degradation of [5-14C] Pyridine-ring labelled test substance in Collombey Soil under Aerobic Conditions
Time |
Volatiles |
Vol. Total |
Extractable |
Non-Extractable |
Total Recovery |
|||
NaOH |
H2SO4 |
|
Cold |
Soxhlet |
Total |
|||
[% Radioactivity applied] |
||||||||
0 |
0.00 |
0.00 |
0.00 |
107.10 |
1.85 |
108.95 |
2.10 |
111.05 |
1 |
0.09 |
0.00 |
0.09 |
89.83 |
4.26 |
94.10 |
3.32 |
97.51 |
3 |
0.22 |
0.00 |
0.22 |
82.13 |
11.27 |
93.39 |
9.00 |
102.61 |
7 |
0.17 |
0.01 |
0.18 |
76.87 |
10.08 |
86.96 |
6.59 |
93.72 |
14 |
2.27 |
0.00 |
2.27 |
62.75 |
11.66 |
74.41 |
17.36 |
94.04 |
30 |
5.10 |
0.00 |
5.10 |
47.54 |
14.78 |
62.32 |
23.97 |
91.38 |
59 |
11.09 |
0.01 |
11.10 |
33.90 |
11.34 |
45.24 |
39.77 |
96.11 |
90 [#1] |
13.01 |
0.00 |
13.01 |
25.63 |
0.00 |
25.63 |
60.53 |
99.17 |
150 [#2] |
18.64 |
0.01 |
18.65 |
17.77 |
0.00 |
17.77 |
65.95 |
102.37 |
272 |
26.68 |
0.00 |
26.68 |
11.33 |
10.32 |
21.65 |
44.38 |
92.72 |
363 |
30.55 |
0.00 |
30.55 |
9.91 |
6.92 |
16.84 |
47.37 |
94.76 |
(#1] (#2]: After Soxhlet extraction the total recovery of these samples were below 90%, respectively. Therefore soil samples were combusted after cold extraction (without Soxhlet extraction). The latter results were used for the balance table (The amount of radioactivity recovered by soxhlet extraction was: [#1]: 9.12% [#2]: 6.65%)
Table: Harsh Extraction of selected Samples
Soil (aerobic incubation) |
Sampling Time |
Method A |
Method B |
Total |
[days] |
[% Appl.] |
|||
Evouettes |
150 |
4.63 |
1.55 |
6.18 |
Evouettes |
272 |
4.69 |
1.97 |
6.66 |
Collombey |
90 |
6.40 |
2.56 |
8.96 |
Collombey |
272 |
2.97 |
2.13 |
5.10 |
A) Reflux with acetonitrile / water 4:1 / 2 h
B) Reflux with acetonitrile / 0.1 mol HCL 9:1 / 2 h
Tables: Degradation Kinetics of the test substance and major Metabolites in Les Evouettes and Collombey Soil under Aerobic Conditions
|
Les Evouettes |
||
Test substance |
M1 |
MB5 |
|
Chi-squared |
20.17606 |
4.34182 |
0.62187 |
C01 |
78.08451 |
14.48262 |
20.30684 |
k1 (per day) |
0.24990 |
0.03087 |
0.00178 |
C02 |
20.8 |
39.7 |
- |
k2 (per day) |
0.00681 |
0.00607 |
- |
DT-50(1) (days) |
3 |
- |
- |
DT-50(2) (days) |
102 |
- |
- |
DT-50ov (days) |
4 |
74 |
389 |
DT-90ov (days) |
104 |
330 |
1294 |
|
Collombey |
|||
Test substance |
M1 |
MB4 |
MB5 |
|
Chi-squared |
4.76185 |
1.03539 |
1.33043 |
7.3308 |
C01 |
63.23869 |
39.79676 |
6.20919 |
22.87503 |
k1 (per day) |
0.49955 |
0.03379 |
0.00207 |
0.00889 |
C02 |
32.3 |
0.58849 |
- |
- |
k2 (per day) |
0.06751 |
4.15l5E-07 |
- |
- |
DT-50(1) (days) |
1 |
- |
- |
- |
DT-50(2) (days) |
10 |
- |
- |
- |
DT-50ov (days) |
2 |
21 |
335 |
78 |
DT-90ov (days) |
18 |
73 |
1112 |
259 |
DT-50(1): of fast degradation reactions
DT-50(2): of slow degradation reactions
DT-50ov: overall
DT-90ov: overall
Table: Distribution and Recovery of Radioactivity in [Pyridinyl-14C]-test substance Treated Soil
Sampling Interval |
0 DAT |
6 HAT |
12 HAT |
1 DAT |
2 DAT |
5 DAT |
10 DAT |
|||||||
Unit Code |
A1 |
A2 |
A5 |
A10 |
B25 |
B26 |
A9 |
A6 |
A7 |
A8 |
A11 |
A12 |
A13 |
A14 |
Initial Soil Extract (Ext 1) |
92.9 |
94.8 |
90.0 |
92.5 |
90.5 |
89.1 |
88.7 |
88.2 |
86.9 |
84.3 |
73.3 |
73.6 |
57.2 |
57.5 |
Mean |
93.9 |
91.3 |
89.8 |
88.5 |
85.6 |
73.5 |
57.4 |
|||||||
Residue |
4.2 |
4.5 |
6.9 |
6.0 |
7.1 |
7.1 |
8.9 |
8.4 |
10.8 |
10.7 |
17.7 |
17.5 |
23.3 |
22.4 |
Mean |
4.4 |
6.5 |
7.1 |
8.7 |
10.8 |
17.6 |
22.9 |
|||||||
Total in Soil |
97.1 |
99.3 |
96.9 |
98.5 |
97.6 |
96.2 |
97.6 |
96.6 |
97.7 |
95.0 |
91.0 |
91.1 |
80.5 |
79.9 |
Mean |
97.9 |
97.7 |
96.9 |
97.1 |
96.4 |
91.1 |
80.2 |
|||||||
Sodium Hydroxide Trap 1 |
NA |
NA |
0.2 |
0.2 |
0.4 |
0.3 |
0.7 |
0.7 |
1.4 |
1.3 |
5.7 |
5.7 |
14.4 |
15.2 |
Mean |
NA |
0.2 |
0.4 |
0.7 |
1.4 |
5.7 |
14.8 |
|||||||
Sodium Hydroxide Trap 2 |
NA |
NA |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
0.1 |
0.3 |
ND |
ND |
ND |
Mean |
NA |
ND |
ND |
ND |
0.1 |
0.2 |
ND |
|||||||
Total in Traps |
NA |
NA |
0.2 |
0.2 |
0.4 |
0.3 |
0.8 |
0.7 |
1.4 |
1.4 |
6.0 |
5.7 |
14.4 |
15.2 |
Mean |
NA |
0.2 |
0.4 |
0.8 |
1.4 |
5.9 |
14.8 |
|||||||
Mass Balance |
97.1 |
99.3 |
97.1 |
98.7 |
98.0 |
96.5 |
98.4 |
97.3 |
99.1 |
96.4 |
97.0 |
96.8 |
94.9 |
95.1 |
Mean |
98.2 |
97.9 |
97.3 |
97.9 |
97.8 |
96.9 |
95.0 |
|||||||
Continued
Sampling Interval |
15 DAT |
24 DAT |
50 DAT |
80 DAT |
120 DAT |
|||||
Unit Code |
A15 |
A16 |
A17 |
A18 |
A19 |
A20 |
A21 |
A22 |
A23 |
A24 |
Initial Soil Extract (Ext 1) |
45.5 |
45.4 |
31.5 |
30.5 |
14.3 |
14.3 |
7.2 |
6.5 |
4.0 |
3.9 |
Mean |
45.5 |
31.0 |
14.3 |
6.9 |
4.0 |
|||||
Residue |
24.9 |
25.5 |
26.5 |
27.0 |
23.8 |
23.7 |
21.4 |
23.8 |
20.0 |
19.1 |
Mean |
25.2 |
26.8 |
23.8 |
22.6 |
19.6 |
|||||
Total in Soil |
70.4 |
70.9 |
58.0 |
57.5 |
38.1 |
38.0 |
28.6 |
30.3 |
24.0 |
23.0 |
Mean |
70.7 |
57.8 |
38.1 |
29.5 |
23.5 |
|||||
Sodium Hydroxide Trap 1 |
22.9 |
23.4 |
36.2 |
36.1 |
57.7 |
57.0 |
66.9 |
65.9 |
72.4 |
72.8 |
Mean |
23.2 |
36.2 |
57.4 |
66.4 |
72.6 |
|||||
Sodium Hydroxide Trap 2 |
ND |
ND |
0.1 |
ND |
ND |
0.1 |
ND |
0.5 |
ND |
0.3 |
Mean |
ND |
0.1 |
0.1 |
0.3 |
0.2 |
|||||
Total in Traps |
22.9 |
23.4 |
36.3 |
36.2 |
57.7 |
57.0 |
66.9 |
66.4 |
72.4 |
73.1 |
Mean |
23.2 |
36.3 |
57.4 |
66.7 |
72.8 |
|||||
Mass Balance |
93.3 |
94.3 |
94.3 |
93.7 |
95.8 |
95.0 |
95.5 |
96.7 |
96.4 |
96.1 |
Mean |
93.8 |
94.0 |
95.4 |
96.1 |
96.3 |
|||||
All values are % applied radioactivity
HAT – Hours after treatment, DAT – Days after treatment
NA – Not Applicable, ND – Not detected (< 0.1%)
Table: Distribution and Recovery of Radioactivity in [Triazinyl-14C]-test substance Treated Soil
Sampling Interval |
0 DAT |
6 HAT |
12 HAT |
1 DAT |
2 DAT |
5 DAT |
10 DAT |
|||||||
Unit Code |
B1 |
B2 |
B9 |
B10 |
B17 |
B18 |
B5 |
B6 |
B7 |
B8 |
B11 |
B12 |
B13 |
B14 |
Initial Soil Extract (Ext 1) |
99.8 |
97.7 |
90.6 |
90.2 |
93.0 |
91.6 |
88.1 |
85.3 |
86.6 |
84.7 |
72.9 |
74.4 |
62.0 |
61.2 |
Mean |
98.8 |
90.4 |
92.3 |
86.7 |
85.7 |
73.7 |
61.6 |
|||||||
Secondary Soil Extract (Ext 4 and 5) |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
Mean |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
|||||||
Reflux Extract (Ext 6) |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
Mean |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
|||||||
Residue |
3.8 |
4.0 |
6.4 |
6.4 |
6.9 |
7.6 |
8.9 |
9.0 |
11.2 |
12.2 |
20.4 |
20.3 |
27.7 |
27.6 |
Mean |
3.9 |
6.4 |
7.3 |
9.0 |
11.7 |
20.4 |
27.7 |
|||||||
Total in Soil |
103.6 |
101.7 |
97.0 |
96.6 |
99.9 |
99.2 |
97.0 |
94.3 |
97.8 |
96.9 |
93.3 |
94.7 |
89.7 |
88.8 |
Mean |
102.7 |
96.8 |
99.6 |
95.7 |
97.4 |
94.0 |
89.3 |
|||||||
Sodium Hydroxide Trap 1 |
NA |
NA |
ND |
ND |
ND |
ND |
0.1 |
0.1 |
0.1 |
0.2 |
1.1 |
1.1 |
3.8 |
3.9 |
Mean |
NA |
ND |
ND |
0.1 |
0.2 |
1.1 |
3.9 |
|||||||
Sodium Hydroxide Trap 2 |
NA |
NA |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
Mean |
NA |
ND |
ND |
ND |
ND |
ND |
ND |
|||||||
Total in Traps |
NA |
NA |
ND |
ND |
ND |
ND |
0.1 |
0.1 |
0.1 |
0.2 |
1.1 |
1.1 |
3.8 |
3.9 |
Mean |
NA |
ND |
ND |
0.1 |
0.2 |
1.1 |
3.9 |
|||||||
Mass Balance |
103.6 |
101.7 |
97.0 |
96.6 |
99.9 |
99.2 |
97.1 |
94.4 |
97.9 |
97.1 |
94.4 |
95.8 |
93.5 |
92.7 |
Mean |
102.7 |
96.8 |
99.6 |
95.8 |
97.5 |
95.1 |
93.1 |
|||||||
Continued
Sampling Interval |
15 DAT |
24 DAT |
50 DAT |
80 DAT |
120 DAT |
|||||
Unit Code |
B15 |
B16 |
B3 |
B4 |
B19 |
B20 |
B21 |
B22 |
B23 |
B24 |
Initial Soil Extract (Ext 1) |
53.7 |
52.6 |
40.7 |
39.8 |
26.6 |
27.7 |
15.5 |
15.8 |
11.6 |
12.3 |
Mean |
53.2 |
40.3 |
27.2 |
15.7 |
12.0 |
|||||
Secondary Soil Extract (Ext 4 and 5) |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
4.2 |
Mean |
NA |
NA |
NA |
NA |
NA |
|||||
Reflux Extract (Ext 6) |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
NA |
8.3 |
Mean |
NA |
NA |
NA |
NA |
NA |
|||||
Residue |
32.6 |
35.1 |
42.1 |
40.0 |
47.2 |
46.5 |
52.9 |
52.4 |
49.1 |
37.5 |
Mean |
33.9 |
41.1 |
46.9 |
52.7 |
43.3 |
|||||
Total in Soil |
86.3 |
87.7 |
82.8 |
79.8 |
73.8 |
74.2 |
68.4 |
68.2 |
60.7 |
62.3 |
Mean |
87.0 |
81.3 |
74.0 |
68.3 |
61.5 |
|||||
Sodium Hydroxide Trap 1 |
6.6 |
6.5 |
10.6 |
10.9 |
18.4 |
19.1 |
24.7 |
23.8 |
31.0 |
30.6 |
Mean |
6.6 |
10.8 |
18.8 |
24.3 |
30.8 |
|||||
Sodium Hydroxide Trap 2 |
ND |
0.1 |
ND |
0.1 |
ND |
0.1 |
ND |
ND |
ND |
0.1 |
Mean |
0.1 |
0.1 |
0.1 |
ND |
0.1 |
|||||
Total in Traps |
6.6 |
6.6 |
10.6 |
11.1 |
18.4 |
19.2 |
24.7 |
23.9 |
31.1 |
30.7 |
Mean |
6.6 |
10.9 |
18.8 |
24.3 |
30.9 |
|||||
Mass Balance |
92.9 |
94.3 |
93.4 |
90.9 |
92.2 |
93.4 |
93.1 |
92.1 |
91.8 |
93.0 |
Mean |
93.6 |
92.2 |
92.8 |
92.6 |
92.4 |
|||||
All values are % applied radioactivity
HAT – Hours after treatment, DAT – Days after treatment
NA – Not Applicable, ND – Not detected (< 0.1%)
Table: Summary of DegT50 Values
Radiolabel |
SFO |
||||
DegT50(days) |
DegT90(days) |
Chi2 |
R2 |
Prob > t |
|
Both Labels |
5 |
16 |
7.39 |
0.9875 |
1.3 x 10-26 |
Description of key information
Aerobic biodegradation in soil has been evaluated in a variety of soils across multiple studies. The laboratory half-life in soil ranges from 2 days in sandy loam to 29.1 days in sand. An overall geometric mean (n = 8) DT50 of 4.6 days was derived.
All available data was assessed and the studies representing the worst-case effects were included as weight-of-evidence studies. Other studies are included as supporting information. The weight-of-evidence studies are considered to be worst-case and were selected for the CSA.
Key value for chemical safety assessment
- Half-life in soil:
- 4.6 d
- at the temperature of:
- 20 °C
Additional information
Table: Overview of available data for the test item on biodegradation in soil
Method |
Guideline / GLP |
Endpoint |
Value (days) |
Reference |
|||
Test medium |
pH |
CEC (meq/100g soil dw) |
%OC |
||||
Sandy clay Loam (18 Acres) |
6.9 |
18.9 |
2.5 |
OECD TG 307 / GLP |
DT50 |
5 |
Dixon, 2012 |
Silt loam (Les Evouettes) |
7.3 |
14.00 |
2.1 |
BBA Part IV 4-1 |
DT50 |
4 |
Schulze-Aurich, 1996 |
Sandy loam (Collombey) |
7.2 |
11.90 |
1.70 |
DT50 |
2 |
||
Silt loam (Les Evouettes) |
7.3 |
14.0 |
2.3 |
BBA Part IV 4-1 |
DT50 |
5.4 |
Kirkpatrick, 1996 |
Loamy sand (Collombey) |
7.2 |
13.9 |
1.9 |
DT50 |
4.8 |
||
Sand (Speyer 2.2) |
6.6 |
11.6 |
1.98 |
DT50 |
29.1 |
||
Silt loam (Les Evouettes) |
7.0 |
17.66 |
2.7 |
BBA Part IV 4-1 |
DT50 |
2.9 |
Gonzalez-Valero, 1996 |
Loamy sand (Collombey) |
7.2 |
14.95 |
2.2 |
DT50 |
2.3 |
||
Overall geometric mean (n=8) |
4.6 |
|
|||||
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
