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EC number: 237-198-5 | CAS number: 13684-56-5
Biodegradation in water and sediment: simulation tests
Administrative data
Link to relevant study record(s)
- Endpoint:
- biodegradation in water and sediment: simulation testing, other
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2004-08-31 to 2005-02-16.
Amended: 2006-02-28 - Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Reason / purpose for cross-reference:
- reference to other study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 308 (Aerobic and Anaerobic Transformation in Aquatic Sediment Systems)
- GLP compliance:
- yes (incl. QA statement)
- Radiolabelling:
- yes
- Oxygen conditions:
- aerobic
- Inoculum or test system:
- natural water / sediment: freshwater
- Details on inoculum:
- - Source of inoculum wastewater (e.g. location, contamination history): Fresh water aquatic-sediment systems Turkey Creek and Choptank River Both from USA
- Storage conditions: The sediment and associated water were stored under refrigerated conditions.
- Temperature (°C) at time of collection, Oxygen concentration (mg/L), pH at time of collection: The temperature, pH and dissolved oxygen of the waters were measured at the time of collection.
- Other: The study was carried out using two water/sediment systems originating from Turkey Creek (USA) and Upper Choptank River (USA). Aerobic sediment samples were collected from the upper 5-10 cm sediment layer under approximately 1-8 cm of water. Aerobic water samples were collected at the surface (air-water interface) from the same locations. The sediments were passed through a 2.0 mm sieve. The characteristics of the sediment and the associated water layer are summarised in Table 1 and Table 2. - Duration of test (contact time):
- 100 d
- Initial conc.:
- 25 µg/L
- Based on:
- act. ingr.
- Parameter followed for biodegradation estimation:
- radiochem. meas.
- Details on study design:
- TEST CONDITIONS
- Solubilising agent (type and concentration if used):
- Test temperature: The mineralisation chambers were placed in water baths set to maintain approximately 20 °C. The water baths were covered with aluminium foil to protect the test chambers from light.
The transformation and characterization test chambers were placed in a temperature-controlled chamber, set to maintain approximately 20 °C, for acclimation and testing. The acclimation period lasted seven days. Additional abiotic test chambers were prepared with sterilized water and sediment.
- Continuous darkness: yes
- Other: Three different test systems were used for transformation, mineralisation and characterisation. Transformation test chambers: Each flask contained 100 or 150 g saturated sediment for Turkey Creek and Choptank River test chambers, respectively, and 280 mL water for Turkey Creek test chambers and 420 mL for Choptank River test chambers, corresponding to a target ratio of sediment to water of 3.6 to 1. The inlet tube was connected to an in- house air supply. Air was continuously purged through the test chambers at a slow rate. The outlet tube was connected to the trapping apparatus consisting of three glass bottles. The first bottle was empty, while the other two bottles each contained 100 mL of trapping solution. The trapping solution was 1.5 N KOH in water, and was intended to trap CO2. Gasses leaving each test chamber passed through an empty bottle, and then bubbled through two KOH traps.
The mineralisation test chambers: Each flask contained 150 or 220 g saturated sediment for Turkey Creek and Choptank River test chambers, respectively, and 280 mL water for Turkey Creek test chambers and 420 mL for Choptank River test chambers, corresponding to a target ratio of sediment to water of 3.6 to 1. The inlet tube was connected to an air supply, while the other outlet tube was connected to the trapping apparatus. Air was continuously purged through the test chambers, and the flow meter was adjusted to provide a bubbling rate of approximately 7 to 15 bubbles every 10 seconds in the traps. The displaced gasses passed through an empty trap bottle, two bottles containing trapping solution, another empty bottle, a quartz column packed with cupric oxide inserted through a tube furnace, another empty trap, and two more traps containing trapping solution. The trapping solution was 1.5 N KOH in water. Each non-empty trap was filled with 100 mL of trapping solution. The tube furnaces were maintained at approximately 800 °C, and temperatures were recorded each working day
The characterization test chambers: Each flask contained 520 or and 480 g saturated sediment for Turkey Creek and Choptank River test chambers, respectively, and 1465 mL water for Turkey Creek test chambers and 920 mL for Choptank River test chambers, corresponding to a target ratio of sediment to water of 3.6 to 1. The inlet tube was connected to an inhouse air supply. Air was continuously purged through the characterization chambers at a slow rate.
The application solutions were added directly to the water layer in each test chamber. The nominal concentration of test substance in the water layer of all treated test chambers was 25 µg a.s./L. The application rate was equivalent to a surface application rate of 250 g a.s./ha, applied to a water column 100 cm in depth. - Reference substance:
- aniline
- Compartment:
- natural water / sediment
- DT50:
- 2 d
- Temp.:
- 20 °C
- Remarks on result:
- other: Turkey Creek System (FOMC modelling)
- Compartment:
- natural water / sediment
- DT50:
- 0.85 d
- Temp.:
- 20 °C
- Remarks on result:
- other: Choptank River System (FOMC modelling)
- Transformation products:
- yes
- No.:
- #1
- Details on transformation products:
- FORMATION AND DECLINE OF EACH TRANSFORMATION PRODUCT DURING TEST & FORMATION AND DECLINE OF EACH TRANSFORMATION PRODUCT DURING TEST:
The amount of desmedipham decreased in the water of Turkey Creek test systems from from 92.2 to 4.2% AR. In Choptank River test systems the amount of desmedipham decreased from from 71.5% to 1.5% AR. The region labeled 'Polars' represented the non-retained or early eluting materials. Small peaks were observed in regions 2 and 3 for some samples. These peaks were usually broad and indistinct, and the materials were not identified. The radioactivity found in regions 1 & 4 were summed and presented as "Others".
In the sediment of Turkey Creek desmedipham was detected with amounts = 0.2% AR. In sediment of Choptank River test systems, desmedipham was detected only in one replicate with 11.4% AR. Aniline reached a maximum amount of 15.0% AR decreased to 10.2% AR in Turkey Creek test systems. In sediment of Choptank River test systems, aniline was detected with 10% AR in one replicate at DAT-0.
In the total Turkey Creek system, desmedipham decreased from 92.2% AR to 4.2% AR. In total Choptank River systems, desmedipham decreased from 77.2% AR to 1.5% AR. In total Turkey Creek system aniline reached a maximum amount of 16.2% AR and declined to 0.9% AR. In total Choptank River system aniline reached a maximum amount of 11.5% AR and declined to 0.2% AR. - Details on results:
- Results indicated that the anticipated standardized aerobic conditions were maintained over the duration of the laboratory study. The measured amounts of dissolved oxygen, pH values and redox potentials are presented above.
A summary of key data on total recovery and the distribution of radioactivity into the various components formed in water and sediment is given in Table 3 and Table 4.
Material balance:
The amount of desmedipham decreased in the water of Turkey Creek test systems from from 92.2 to 4.2% AR. In Choptank River test systems the amount of desmedipham decreased from from 71.5% to 1.5% AR. The total radioactivity found in each transformation test chamber was calculated from the sum of the amounts found in the aqueous fractions, sediment extracts, and solids remaining after extraction. These totals were added to the cumulative total 14C-gasses found in the mineralization chambers at each sampling interval to determine the material balances. On DAT-0, the material balances were greater than 100% AR. At the end of the test, the mean material balances for both abiotic test systems were > 91% AR; the mean material balance for the biotic Turkey Creek systems was 89% (Table 1); and the mean material balance for the biotic Choptank River systems was 81% AR (Table 2). Material balances declined as more mineralization occured. This was most likely due to variances between the transformation and mineralization test systems.
Volatilisation
The abiotic test chambers demonstrated the least amount of mineralisation with mean cumulative totals of 0.4% AR for both test systems. The mean cumulative totals from the biotic test chambers were 33% AR for the Turkey Creek systems and 35% AR for the Choptank River systems. Most of the cumulative total 14C-gasses (> 99% AR) from the biotic systems was found in the "CO2" traps. The contribution of total radioactivity recovered from the spacing bottles was most likely due to transfer of some of the KOH solution from the other traps. - Conclusions:
- Desmedipham was hydrolyzed in aquatic systems to form aniline. The half-life of desmedipham was estimated to be approximately 0.6 days in Turkey Creek Systems and 1.4 days in Choptank River Systems.
The largest percentages of the hydrolysis products were found in the abiotic aqueous fractions collected 6 hours after dosing.
The greatest amounts of radioactivity in the sediment extracts were found in samples collected through day 14 for the biotic systems, and on day 100 for the abiotic systems.
Desmedipham dissipated from the aqueous-sediment systems. Following hydrolysis, the 14C products were mineralized. By the end of the test, the total 14CO2 produced from biotic systems was approximately 34%, and less than 1% from abiotic systems. - Executive summary:
The aerobic aquatic metabolism of desmedipham was investigated in two fresh water aquatic-sediment systems Turkey Creek and Choptank River Both from USA, using [aniline-UL-14C]desmedipham, at 20 °C in the dark for up to 101 days. A study application rate of 25µg/L was applied. The application rate was equivalent to a surface application rate of 250 g a.s./ha, applied to a water column 100 cm in depth. The mean material balances for all four test systems were > 90% AR. The amount of desmedipham decreased in the water of Turkey Creek test systems from 92.2 to 4.2% AR. In Choptank River test systems the amount of desmedipham decreased from 71.5% to 1.5% AR. One major metabolite was identified as aniline with mean maximum amounts of 8.7 and 11.5% AR, decreasing to 0.9% AR (DAT-14) and 0.2% AR (DAT-30) in Turkey Creek and Choptank River test systems, respectively.
The degradation of desmedipham in total system was fast in both river systems resulting to best fit DT50 values of 1.3 and 0.37 days in Turkey Creek and Choptank River, respectively. The respective DT90 values were 6.7 and 2.8 days. The max amount of desmedipham found in sediment was 11.4 % in Choptank River. It was not possible to calculate Level II degradation values for water and sediment phases for aniline labeled desmedipham in either system due to too little data available for sediments. In the sediment of Turkey Creek desmedipham was detected with amounts ≤ 0.2 AR until DAT 7. In sediment of Choptank River test systems, desmedipham was detected only in one replicate at DAT-0 with 11.4% AR.
Desmedipham was rapidly hydrolysed to its main metabolite aniline in the water phase. Aniline was further degraded, but no DT50 values could be obtained due to inconsistent residue decline.
The amount of CO2 increased to 32.5 and 31.8 % of AR at the end of the test showing quite high rate of mineralisation in both systems. The amout of CO2 in abiotic systems was 1% of AR showing the importance of microbial degradation for mineralization.
- Endpoint:
- biodegradation in water: simulation testing on ultimate degradation in surface water
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2013-01-03 to 2014-02-07
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Reason / purpose for cross-reference:
- reference to other study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test)
- Version / remarks:
- 2004
- GLP compliance:
- yes (incl. QA statement)
- Radiolabelling:
- yes
- Oxygen conditions:
- aerobic
- Inoculum or test system:
- natural water
- Remarks:
- Pond water
- Details on source and properties of surface water:
- - Details on collection (e.g. location, sampling depth, contamination history, procedure): Water was freshly sampled from a pond in Biederthal, France in December, 2012. The sampling site is specified in the table below. The water was sampled from the surface at a depth of about 0 to 10 cm. The sampling location was in an area not submitted to effluent discharges and located far from human activity.
- Storage conditions: 4 °C in the dark.
- Type and size of filter used, if any: The sample was transported in sealed containers and filtered through a 0.2 mm sieve. - Duration of test (contact time):
- 62 d
- Initial conc.:
- 0.01 mg/L
- Based on:
- test mat.
- Initial conc.:
- 0.1 mg/L
- Based on:
- test mat.
- Parameter followed for biodegradation estimation:
- radiochem. meas.
- Details on study design:
- TEST CONDITIONS
- Volume of test solution/treatment: Each system consisted of an open gas-flow-system with 300 mL conical flasks containing 100 mL of natural water.
- Test temperature: Samples were incubated at a controlled temperature of 21.0 ± 0.2 °C in the dark, under aerobic conditions.
- Other: Application rates of 0.1 and 0.01 mg/L were applied for the low and the high concentration samples, respectively. In addition, an experiment was performed under sterile conditions at the high concentration. Methanol was used for the preparation of the application solutions. Each flask was aerated with moistened air. The samples were continuously and gently stirred to maintain particles and micro-organisms in suspension. Agitation also facilitated oxygen transfer from headspace to liquid, in a way that aerobic conditions were maintained. Additionally, degradation of [14C-U] benzoic acid was monitored using the same experimental set- up in order to test the microbial activity of the test water.
After treatment, samples were connected to a trapping system equipped with a total of two absorption traps, one containing ethylene glycol and the other 2N NaOH (in this sequence) to trap organic volatiles and 14CO2, respectively. - Reference substance:
- benzoic acid, sodium salt
- Remarks:
- Radiolabelled benzoic acid
- Compartment:
- natural water
- % Recovery:
- 100.9
- Remarks on result:
- other: 0 DAT
- Compartment:
- natural water
- % CO2:
- 0.1
- % Other volatiles:
- 1.6
- % Recovery:
- 104.2
- Remarks on result:
- other: 1 DAT
- Compartment:
- natural water
- % CO2:
- 0.2
- % Other volatiles:
- 3
- % Recovery:
- 101.4
- Remarks on result:
- other: 3 DAT
- Compartment:
- natural water
- % CO2:
- 1
- % Other volatiles:
- 10.4
- % Recovery:
- 99.5
- Remarks on result:
- other: 7 DAT
- Compartment:
- natural water
- % CO2:
- 2
- % Other volatiles:
- 49.5
- % Recovery:
- 98
- Remarks on result:
- other: 14 DAT
- Compartment:
- natural water
- % CO2:
- 2.3
- % Other volatiles:
- 25.9
- % Recovery:
- 99.3
- Remarks on result:
- other: 30 DAT
- Compartment:
- natural water
- % CO2:
- 5
- % Other volatiles:
- 43.9
- % Recovery:
- 101.9
- Remarks on result:
- other: 62 DAT
- DT50:
- < 1 d
- Temp.:
- 21 °C
- Remarks on result:
- other: As the test item completely degraded within one day of incubation, no degradation rates were calculated.
- Transformation products:
- not specified
- Remarks:
- Diphenyl urea (not detected in low system) & Aniline
- Details on transformation products:
- At the first sampling interval (time 0), the test item represented 100.9%, 101.3% and 101.0% AR in the high dose, high dose sterile and low dose system, respectively.
- Maximum occurrence of each transformation product:
In all systems, desmedipham degraded rapidly within the first 24 hours of incubation under formation of metabolite M2, which was identified as aniline by co-chromatography using HPLC and TLC. The amount of aniline, representing 102.5, 99.3 and 96.8% AR in the high dose, high dose sterile and low dose system at DAT- 1, respectively, declined to 53.0, 58.0 and 41.3% AR in the respective systems until DAT-62. Subsequently, in the high dose system a minor metabolite M1, characterized as diphenyl urea by LC-MS/MS and co- chromatography, was detected and represented 18.0, 3.2 and 4.0% AR (mean values) at DAT-3, 7 and 14, respectively. Formation of diphenyl urea was also observed in the high dose sterile system from DAT-3 to DAT- 62, with mean values between 3.4% and 17.2% of AR. However, diphenyl urea could not be detected in the low dose test system. - Volatile metabolites:
- yes
- Details on results:
- Results indicated that the anticipated standardized conditions were maintained and that the water was microbially active. The pH in the water ranged from 7.61 to 8.44 for all test systems treated with desmedipham. Oxygen contents (range from 6.21 to 9.30 mg/L) indicated aerobic conditions in the water for all experiments. Similar values were determined in untreated control samples which demonstrate that the test item had no significant effects on the physico-chemical parameters of the test system.
The total mean recoveries were 100.7 ± 2.6% AR for the high dose, 100.2 ± 3.2% AR for the high dose sterile and 98.8 ± 2.2% AR for the low dose experiment.
Formation of radioactive carbon dioxide represented 5.0% AR in the high dose, 0.1% AR in the sterile and 5.2% AR in the low dose system after 62 days. The amount of radioactive carbon dioxide, dissolved in the water layer, was negligible. Within 62 days of incubation, volatile products other than 14CO2 increased from initially 0% to 43.9%, 33.0% and 51.3% AR in the water phase of the high dose, high dose sterile and low dose system, respectively.
RESULTS OF SUPPLEMENTARY EXPERIMENT (if any): The reference substance benzoic acid degraded from initially 92.3% to 0% of AR within 7 days of incubation indicating high microbial activity in the test water. - Results with reference substance:
- The reference substance benzoic acid degraded from initially 92.3% to 0% of AR within 7 days of incubation indicating high microbial activity in the test water.
- Conclusions:
- In conclusion, desmedipham, regardless of its concentration, degraded rapidly in natural surface water systems within 24 hours of incubation.
The main metabolite, in both high dose and low dose system, was aniline (M2). Subsequently, in the high dose system a minor metabolite M1, characterized as diphenylurea by LC-MS/MS and co-chromatography, was detected and accounted for 18.0%, 3.2% and 4.0% of AR (mean values) after 3, 7 and 14 days of incubation, respectively. In addition the formation of diphenylurea (M1), with mean values between 3.4% and 17.2% AR, was observed in the high dose sterile system from DAT 3 to DAT 62. - Executive summary:
Aerobic mineralisation of [Aniline-UL-14C] Desmedipham in surface water was investigated under defined laboratory conditions in the dark. For this purpose the radiolabelled test item was applied to 100 mL of natural pond water at concentrations of 0.1 and 0.01 mg/L. Additionally, the high concentration experiment was performed under sterile conditions in order to gain information about abiotic degradability of the test item. The test flasks were incubated for a period of 62 days at 21.0 ± 0.2°C under aerobic conditions by gently stirring the water. Radiolabelled benzoic acid was used as reference substance to check the sufficiency of microbial activity of the test water. Sufficient activity is reached if at least 90% of the acid degrades within 14 days of incubation.
The freshly collected water samples were passed through a 0.2 mm sieve and filled into 350 mL conical flasks. After treatment, the flasks were incubated under continuous ventilation with moistened air. The exiting air was passed through a trapping system consisting of ethylene glycol and sodium hydroxide flasks in series.
Duplicate samples (replicate A and B) per system were then worked up to incubation day 0, 1, 3, 7, 14, 30 and 62. After sampling, the pH and the oxygen concentration in water were determined together with the total radioactivity present in the water layer and in the volatile traps. Aliquots of water samples were then analysed, directly or after a concentration step, by HPLC for parent and metabolites. Radioactive carbon dioxide dissolved in the water layer was extracted from the water layer by adding soda lime followed by acidification and trapping the released carbon dioxide.
Total mean recoveries were 100.7 ± 2.6% of applied radioactivity (AR) for the high dose, 100.2 ± 3.2% AR for the high dose sterile and 98.8 ± 2.2% AR for the low dose experiments.
Immediately after treatment (time 0), mean values of 100.9%, 101.3% and 101.0% of AR were measured in the water phases of the high dose, high dose sterile and low dose system, respectively. After 62 days of incubation, the amount of radioactivity (mean values) in the respective systems represented 53.0% of AR for the high dose, 64.9% of AR for the high dose sterile and 41.3% of AR for the low dose system. Correspondingly, radioactive carbon dioxide represented 5.0% of AR in the high dose, 0.1% of AR in the sterile and 5.2% of AR in the low dose system after 62 days. Volatile products other than 14CO2 increased from initially 0% to 43.9%, 33.0% and 51.3% of AR in the water phase of the high dose, high dose sterile and low dose system, respectively.
The reference substance benzoic acid degraded completely from initially 92.3% to 0% AR within 7 days of incubation indicating high microbial activity in the test water.
At the first sampling interval (time 0), the test item represented 103.6% and 101.0% of AR in the high dose and low dose system respectively. In both high dose and low dose system the test item degraded completely within the first 24 hours of incubation, under formation of metabolite M2, which was identified by co-chromatography as aniline. The amount of aniline (M2) declined from initially 102.5%, 99.3% and 96.8% of AR in the high dose, high dose sterile and low dose system, respectively at DAT 1 to 53.0%, 58.0% and 41.3% of AR in the respective systems at DAT 62.
Subsequently, a minor metabolite M1, characterized as diphenylurea by LC-MS/MS and cochromatography, was detected in the high dose system, representing 18.0%, 3.2% and 4.0% of AR after 3, 7 and 14 days of incubation, respectively. Formation of diphenylurea (M1), with mean values between 3.4% and 17.2% AR, was also observed in the high dose sterile system from DAT 3 to DAT 62. However, diphenylurea (M1) could not be detected in the low dose test system.
In conclusion, desmedipham, regardless of its concentration, degraded rapidly in natural surface water systems within 24 hours of incubation. The main metabolite, in both the high and low dose system, was aniline (M2). Subsequently, in the high dose system a minor metabolite M1, characterized as diphenylurea by LC-MS/MS and co-chromatography, was detected and accounted for 18.0%, 3.2% and 4.0% of AR (mean values) after 3, 7 and 14 days of incubation, respectively. In addition the formation of diphenylurea (M1), with mean values between 3.6% and 19.0% AR, was observed in the high dose sterile system from DAT 3 to DAT 62.
- Endpoint:
- biodegradation in water: sediment simulation testing
- Type of information:
- calculation (if not (Q)SAR)
- Adequacy of study:
- key study
- Study period:
- 13-07-2016
- Reliability:
- 1 (reliable without restriction)
- Reason / purpose for cross-reference:
- reference to other study
- Reason / purpose for cross-reference:
- reference to other study
- Reason / purpose for cross-reference:
- reference to other study
- Reason / purpose for cross-reference:
- reference to other study
- Reason / purpose for cross-reference:
- reference to other study
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Data were processed and evaluated according to the recommendations of the FOCUS kinetics reports (FOCUS, 2006).
- GLP compliance:
- no
- Remarks:
- GLP is not relevant for studies following FOCUS guidance to calculate endpoints.
- Specific details on test material used for the study:
- The test material is desmedipham
- Inoculum or test system:
- other: FOCUS - Kinetic evaluation
- Details on study design:
- Figure 1 shows the proposed metabolism scheme which includes the relevant pathways in water-sediment systems. The main metabolites are EHPC and aniline.
- Compartment:
- entire system
- DT50:
- 0.093 d
- Type:
- other: SFO
- Temp.:
- 20 °C
- Compartment:
- water
- DT50:
- 0.051 d
- Type:
- other: SFO
- Temp.:
- 20 °C
- Compartment:
- sediment
- DT50:
- 29 d
- Type:
- other: SFO
- Temp.:
- 20 °C
- Transformation products:
- not specified
- Remarks:
- This is a kinetic evaluation
- Details on results:
- Residue data from five aerobic water/sediment degradation studies M-228785-01-1, M-147032-01-1, M-221610-01-1, M-493999-01-1 and M-494009-01-1 were used. In these studies, the degradation of desmedipham was studied in water/sediment systems CMS pond, OCR pond, Illingen pond, Spiegelberg creek, Turkey Creek, Choptank River, OVP, SW, Rhine River and Anwil pond under aerobic conditions in the dark in the laboratory for up to 121 days at 20 °C.
A kinetic analysis of residue data was performed with the software KinGUI 2 according to FOCUS DegKinetics Report (2006) to derive half-lives for desmedipham and its metabolites EHPC and aniline.
The most appropriate kinetic model for modelling purpose and trigger evaluation was selected on the basis of a detailed statistical analysis including visual assessment of the goodness of the fits, chi2 scaled-error criterion, t- test significance, correlation analysis and standard deviation. The DT50 value was calculated from the resulting kinetic parameters. Generally, where the evaluations were done using SFO kinetics, the persistence endpoints are equal to those for modelling purposes. Where desmedipham showed non-SFO behaviour, then modelling and persistence endpoints were obtained using different kinetic models, according to FOCUS (2006).
According to the recommendations of FOCUS (2006), (Level I) dissipation half-lives of desmedipham in water and sediment were determined as well as the degradation DT50 for the total system and formation fractions to the relevant metabolite (EHPC or aniline). The Level II degradation assessment (desmedipham exchange between water and sediment compartments) was also assessed, if possible.
Generally, measured and reported replicates were taken into account separately. The data were checked for consistency and clear outliers. Data for non-extractable residues (NER) and CO2 were not explicitly considered in the evaluation (i.e., open system). The initial amount M0 of the parent substance was fitted, while M0 for the metabolite was fixed to zero. All kinetic rates and formation fractions were optimised for achieving a best fit of the model to the observed residue data. The degradation scheme below was implemented for Level I degradation.
For the residues in the total system, which were evaluated using a compartmental kinetic model describing the whole degradation pathway, the following procedure was applied:
- At day 0, the whole amount of metabolites, non-extractable residues (NER) and CO2 were attributed to the parent compound and respectively metabolite concentrations on day 0 were set to 0 %. Also, parent compound at day 0 was completely attributed to the water phase and its amount in the sediment phase was set to 0 %, as the application was made to the water phase.
- In case of residues below LOQ or LOD, the first non detect at the end of the curve was set to 0.5 X LOQ: the curve can be cut thereafter, if no later detect follows. The last non-detect at the beginning of a curve (for metabolites) was set to 0.5 X LOQ if it occurred later than day 0. Samples reported as < LOQ and lying between two detects were also set to 0.5 X LOQ.
As the fit of the kinetic analysis was not acceptable, a second approach was conducted. This second approach considered physico- chemical properties of desmedipham. Desmedipham has a geomean Koc of 3894 [mL/g] and once it appears in the sediment phase it is very unlikely that it will be transferred back to the water phase due to its highly sorbing properties. - Executive summary:
The degradation and dissipation behaviour of desmedipham in water-sediment systems was investigated by kinetic evaluation of five aerobic laboratory water-sediment studies conducted with 14C-labelled desmedipham (either [phenyl-UL-14C]-AE B049913 or [14C-aniline]-AE B038107) in pairs of test systems.
According to the recommendations of FOCUS (2006), (Level I) dissipation half-lives of desmedipham in water and sediment were determined as well as the degradation DT50 for the total system and formation fractions to the relevant metabolite (EHPC or aniline). An overview of the arithmetic mean DT50 values for use as inputs in environmental fate models is given in (Table 1) as well as for use in assessing persistence endpoints (Table 2). A Level II degradation assessment (desmedipham exchange between water and sediment compartments) was also assessed (Table 1). This was facilitated by the high Koc of desmedipham, allowing a simplification of the process.
Generally, where the evaluations were done using SFO kinetics, the persistence endpoints are equal to those for modelling purposes. Where desmedipham showed a non-SFO behaviour, then modelling and persistence endpoints were obtained using different kinetic models, according to FOCUS (2006).
Table 1: Summary of degradation (DegT50) values in the total system and dissipation (DT50) values in water and sediment of desmedipham and its metabolites EHPC and aniline: for modelling purposes.
Desmedipham
EHPC
Aniline
Compartment
DT50
[d]
DT50
[d]
DT50
[d]
Total system degradation
0.093 (median)
22.6 (geo. mean)
3.7 (geo. mean)
Water dissipation
0.051 (median)
12.4 (geo. mean)
2.2 (geo. mean)
Sediment dissipation
Water/sediment degradation:
29.0 (single value)
54.7 (w/case)
Water: 2.7 (arithmetic mean) Sediment: 21.4 (single value)
Table 2: Summary of of degradation (DegT50) values in the total system and dissipation (DT50) values in water and sediment of desmedipham and its metabolites EHPC and aniline: for checking against persistence triggers.
Desmedipham
EHPC
Aniline
Compartment
DT50
DT50
DT50
[d]
[d]
[d]
Total system degradation
0.093 (median)
18.9 (geo. mean)
3.7 (geo. mean)
Water dissipation
0.051 (median)
10.8 (geo. mean)
34.5 (w/case)
Sediment dissipation
29.0 (single value)
54.7 (w/case)
- Endpoint:
- biodegradation in water: simulation testing on ultimate degradation in surface water
- Type of information:
- calculation (if not (Q)SAR)
- Adequacy of study:
- key study
- Study period:
- 2014-09-17
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Reason / purpose for cross-reference:
- reference to other study
- Qualifier:
- according to guideline
- Guideline:
- other: FOCUS Kinetics Work Group
- Version / remarks:
- 2006, 2011
- GLP compliance:
- no
- Remarks:
- GLP is not relevant for studies following FOCUS guidance to calculate endpoints.
- Radiolabelling:
- yes
- Inoculum or test system:
- other: FOCUS - Kinetic evaluation
- Details on study design:
- The metabolic pathway of desmedipham in surface water proposed in M-477210-01-1 is given in Figure 1. Relevant metabolites of desmedipham in water are aniline and diphenylurea.
- Compartment:
- natural water
- DT50:
- 0.12 d
- Type:
- other: SFO
- Temp.:
- 21 °C
- Remarks on result:
- other: Low conc.
- Key result
- Compartment:
- natural water
- DT50:
- 0.28 d
- Temp.:
- 12 °C
- Remarks on result:
- other: Calculated from 21 °C
- Transformation products:
- yes
- Remarks:
- Diphenyl urea & Aniline
- Details on results:
- Degradation of desmedipham and its metabolites aniline and diphenyl urea was described with SFO kinetics. As the decline phase for aniline could be described well, and due to the good visual and statistical fit, endpoints were derived (Table 1). The pathway fit did not result in satisfactory visual or statistical fit for metabolite diphenyl urea. Therefore, no degradation endpoints were derived for the metabolite diphenyl urea. However, as the overall model fit was good, the pathway fit was used to derive the formation fraction for this metabolite.
As no reliable degradation endpoints could be derived for diphenyl urea from the pathway fit, the decline curve for this metabolite was fitted from its maximum occurrence. The value on sampling day 7 that was initially set to ½ LOD for the pathway fit according to FOCUS (2006; 2011), was excluded in the kinetic fit from maximum occurrence. This resulted in a better model fit and more conservative degradation endpoints. - Conclusions:
- RMS comments and conclusion: The study followed the OECD test guideline 309. According to the OECD TG the most stable parts should be 14C labelled to ensure the determination of the total mineralisation. In this study only the aniline labelled desmedipham was used. Biological activity of the test water was confirmed by the degradation of reference substance UL-14C-benzoic acid within 14 days of incubation. Concentrations were according to the test guideline and the pH of the tested natural water ranged from 7.61 to 8.44 in which pH the hydrolysis is significant. In the hydrolysis studies the DT50 for desmedipham was around 2.4 hours in pH 8. Desmedipham degraded extremely fast in surface water with a half-life of < 1 day. The degradation proceeded by the formation of aniline and diphenyl urea, carbon dioxide and other volatile products. The formation of CO2 was slightly lower in the sterile condition showing the need of microbial degradation for mineralisation. The calculated DT50 values for desmedipham were 0.01 and 0.39 days for high and low concentrations, respectively.
- Executive summary:
The aerobic mineralisation of desmedipham and its metabolites in surface water was investigated under laboratory conditions in the dark in the study M-477210-01-1. The present report describes a kinetic analysis of the residue data of desmedipham and its metabolites in surface water following the guidance of the FOCUS Kinetics Work Group, in order to derive half-lives and formation fractions suitable for use in exposure assessment. The model fit as well as the statistical evaluation of the results was carried out with the in-house developed software KinGUI, version 2.1. The selection of the most appropriate kinetic model was based on a detailed statistical analysis including visual assessment, χ2-error statistic, t-test significance, correlation analysis and standard deviation.
Referenceopen allclose all
Table 3: Degradation of [aniline-UL-14C]desmedipham in water/sediment system Turkey Creek (values expressed as % AR)
Compound/Matrix | Repl. No. | DAT | |||||||||
0 | 0.25 | 1 | 2 | 7 | 14 | 30 | 63 | 100 | |||
desmedipham | Water 1 | 1 2 | 89.4 95.0 | 78.8 74.2 | 55.7 43.4 | 25.3 34.3 | 5.3 2.8 | 5.0 3.3 | n.a. n.a. | n.a. n.a. | n.a. n.a. |
Mean | 92.2 | 76.5 | 49.6 | 29.8 | 4.1 | 4.2 | n.a. | n.a. | n.a. | ||
Sediment | 1 2 | n.a. n.a. | 0.1 0.3 | 0.1 n.a. | n.a. 0.2 | 0.1 0.1 | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | |
Mean | n.a. | 0.2 | 0.1 4 | 0.2 4 | 0.1 | n.a. | n.a. | n.a. | n.a. | ||
Total System 5 | 1 2 | 89.4 95.0 | 78.9 74.5 | 55.8 43.4 | 25.3 34.5 | 5.4 2.9 | 5.0 3.3 | n.a. n.a. | n.a. n.a. | n.a. n.a. | |
Mean | 92.2 | 76.7 | 49.6 | 29.8 | 4.2 | 4.2 | n.a. | n.a. | n.a. | ||
aniline |
Water 1 | 1 2 | 0.4 0.5 | 1.5 2.8 | 7.2 10.1 | 3.1 2.4 | 5.0 0.2 | 0.9 0.9 | n.a. n.a. | n.a. n.a. | n.a. n.a. |
Mean | 0.5 | 2.2 | 8.7 | 2.8 | 2.6 | 0.9 | n.a. | n.a. | n.a. | ||
Sediment | 1 2 | n.a. n.a. | 9.7 13.3 | 15.0 n.a. | n.a. 13.3 | 7.7 12.7 | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | |
Mean | n.a. | 11.5 | 15.0 4 | 13.3 4 | 10.2 | n.a. | n.a. | n.a. | n.a. | ||
Total System 5 | 1 2 | 0.4 0.5 | 11.2 16.1 | 22.2 10.1 | 3.1 15.7 | 12.7 12.9 | 0.9 0.9 | n.a. n.a. | n.a. n.a. | n.a. n.a. | |
Mean | 0.5 | 13.7 | 16.2 | 9.4 | 12.8 | 0.9 | n.a. | n.a. | n.a. | ||
Region 2 2, 6 |
Water | 1 2 Mean | 0.3 0.8 0.5 | 0.2 1.0 0.6 | 0.5 1.5 1.0 | 1.0 0.9 0.9 | 1.2 0.8 1.0 | 1.7 2.0 1.8 | n.a. n.a. n.a. | n.a. n.a. n.a. | n.a. n.a. n.a. |
Region 3 2, 6 |
Water | 1 2 Mean | 1.9 1.5 1.7 | 2.5 2.1 2.3 | 2.4 4.6 3.5 | 2.0 1.9 2.0 | 3.2 2.5 2.9 | 5.0 3.4 4.2 | n.a. n.a. n.a. | n.a. n.a. n.a. | n.a. n.a. n.a. |
Unknown 3 |
Water | 1 2 Mean | n.a. n.a. n.a. | 0.4 0.4 0.4 | 0.5 0.6 0.6 | 2.9 2.1 2.5 | 0.7 n.a. 0.7 4 | 0.3 0.1 0.2 | n.a. n.a. n.a. | n.a. n.a. n.a. | n.a. n.a. n.a. |
Polars 2, 7 |
Water | 1 2 Mean | 0.7 0.9 0.8 | 0.4 0.8 0.6 | 1.0 0.1 0.5 | 0.8 1.3 1.0 | 1.4 0.8 1.1 | 1.1 1.7 1.4 | n.a. n.a. n.a. | n.a. n.a. n.a. | n.a. n.a. n.a. |
Others 8 | Water 1 | Mean | 5.6 | 6.2 | 11.4 | 10.0 | 7.6 | 2.1 | n.a. | n.a. | n.a. |
Sediment | Mean | n.a. | 1.3 | 2.2 | 1.6 | 2.2 | n.a. | n.a. | n.a. | n.a. | |
Total System | Mean | 5.6 | 4.4 | 7.3 | 2.4 | 3.4 | 0.5 | n.a. | n.a. | n.a. | |
Water | 1 2 Mean | 102.9 99.8 101.4 | 96.5 94.8 95.6 | 87.8 92.6 90.2 | 85.9 85.7 85.8 | 49.0 19.1 34.1 | 48.7 40.8 44.7 | 29.6 12.4 21.0 | 14.2 22.2 18.2 | 5.2 6.8 6.0 | |
Extractable Residues | 1 2 Mean | 1.3 0.8 1.0 | 10.7 15.5 13.1 | 17.3 7.8 12.5 | 8.4 15.1 11.7 | 10.4 14.6 12.5 | 9.6 7.1 8.3 | 5.6 6.6 6.1 | 4.1 8.4 6.3 | 6.0 3.1 4.6 | |
Non-extractable Residues | 1 2 | 0.1 0.1 | 2.2 3.4 | 5.2 2.4 | 5.7 6.8 | 31.4 52.4 | 36.0 36.6 | 28.8 51.8 | 36.9 40.2 | 44.1 47.5 | |
Mean | 0.1 | 2.8 | 3.8 | 6.3 | 41.9 | 36.3 | 40.3 | 38.5 | 45.8 | ||
Transformation Chamber Total Recovery | Mean | 102.4 | 111.5 | 106.5 | 103.8 | 88.5 | 89.4 | 67.5 | 63.1 | 56.4 | |
Material Balance 9 | Mean | 102.4 | 111.5 | 106.5 | 103.8 | 88.7 | 90.6 | 77.8 | 85.6 | 89.0 | |
n.a.: not analysed
1 sum of aqueous fraction and ethyl acetate fraction after partitioning of water
2 in ethyl acetate fraction after partitioning of water
3 region just above desmedipham in aqueous fraction after partitioning of water; a small peak was observed in this region for some samples.
4 Results from single samples rather than means
5 single values of water and sediment are summed up to total single values; mean values calculated from total single values
6 small peaks were observed in regions 2 and 3 for some samples. These peaks were usually broad and indistinct
7 non-retained or early eluting materials
8 sum of broad and indistinct radiodetection signals
9 Sum of radioactivity in transformation chambers (water and sediment) and mineralisation chambers
Table 4: Degradation of [aniline-UL-14C]desmedipham in water/sediment system Choptank River (values expressed as % AR)
Compound/Matrix | Repl. No. | DAT | |||||||||
0 | 0.25 | 1 | 2 | 7 | 14 | 30 | 63 | 100 | |||
desmedipham | Water 1 | 1 2 | 65.2 71.0 | 57.3 47.4 | 16.6 17.0 | 10.4 12.3 | 8.1 6.2 | 2.9 4.4 | 3.1 0.1 | 0.1 0.1 | n.a. n.a. |
Mean | 68.1 | 52.4 | 16.8 | 11.4 | 7.15 | 3.7 | 1.6 | 0.1 | n.a. | ||
Sediment | 1 2 | 11.4 n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | |
Mean | 11.4 4 | n.a. | n.a. | n.a. | n.a. | n.a. | n.a. | n.a. | n.a. | ||
Total System 5 | 1 2 | 76.6 71.0 | 57.3 47.4 | 16.6 17.0 | 10.4 12.3 | 8.1 6.2 | 2.9 4.4 | 3.1 0.1 | 0.1 0.1 | n.a. n.a. | |
Mean | 73.8 | 52.4 | 16.8 | 11.4 | 7.15 | 3.7 | 1.6 | 0.1 | n.a. | ||
aniline |
Water 1 | 1 2 | 3.4 2.4 | 2.0 7.1 | 8.2 14.8 | 3.9 3.3 | 10.1 11.5 | 0.5 1.2 | 0.8 0.4 | 0.2 0.1 | n.a. n.a. |
Mean | 2.9 | 4.6 | 11.5 | 3.6 | 10.8 | 0.9 | 0.6 | 0.2 | n.a. | ||
Sediment | 1 2 | 1.0 n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | n.a. n.a. | |
Mean | 1.0 4 | n.a. | n.a. | n.a. | n.a. | n.a. | n.a. | n.a. | n.a. | ||
Total System 5 | 1 2 | 4.4 2.4 | 2.0 7.1 | 8.2 14.8 | 3.9 3.3 | 10.1 11.5 | 0.5 1.2 | 0.8 0.4 | 0.2 0.1 | n.a. n.a. | |
Mean | 3.4 | 4.6 | 11.5 | 3.6 | 10.8 | 0.9 | 0.6 | 0.2 | n.a. | ||
Region 2 2, 6 |
Water | 1 2 Mean | 1.6 1.6 1.6 | 1.1 0.8 1.0 | 1.0 3.2 2.1 | 5.0 5.1 5.0 | 3.5 4.0 3.7 | 3.9 3.8 3.8 | 0.9 n.a. 0.9 4 | n.a. n.a. n.a. | n.a. n.a. n.a. |
Region 3 2, 6 |
Water | 1 2 Mean | 2.1 5.0 3.5 | 4.5 2.3 3.4 | 2.1 2.9 2.5 | 2.6 2.6 2.6 | 6.8 5.3 6.1 | 6.6 5.0 5.8 | 4.5 n.a. 4.5 4 | n.a. n.a. n.a. | n.a. n.a. n.a. |
Unknown 3 |
Water | 1 2 Mean | n.a. n.a. n.a. | 0.4 4.0 2.2 | 1.2 1.8 1.5 | 3.8 3.4 3.6 | 1.5 1.5 1.5 | 0.0 0.4 0.2 | 0.0 0.0 0.0 | 0.0 0.0 0.0 | n.a. n.a. n.a. |
Polars 2, 7 |
Water | 1 2 Mean | 6.2 2.9 4.6 | 0.5 1.9 1.2 | 2.6 0.5 1.6 | 1.3 1.0 1.1 | 2.8 2.9 2.9 | 1.1 1.5 1.3 | 1.3 n.a. 1.3 4 | n.a. n.a. n.a. | n.a. n.a. n.a. |
Others 8 | Water | Mean | 17.0 | 9.8 | 17.1 | 13.5 | 12.3 | 3.6 | 2.3 | 0.6 | n.a. |
Sediment | Mean | 2.0 | n.a. | n.a. | n.a. | n.a. | n.a. | n.a. | n.a. | n.a. | |
Total System | Mean | 19.0 | 9.8 | 17.1 | 13.5 | 12.3 | 3.6 | 2.3 | 0.6 | n.a. | |
Water | 1 2 Mean | 101.2 102.2 101.7 | 92.6 97.6 95.1 | 92.1 94.2 93.2 | 88.5 91.2 89.8 | 81.3 82.6 81.9 | 42.1 57.0 49.6 | 39.6 29.0 34.3 | 27.6 22.4 25.0 | 12.7 13.5 13.1 | |
Extractable Residues | 1 2 Mean | 14.4 2.8 8.6 | 7.0 2.7 4.8 | 6.3 5.3 5.8 | 6.3 4.9 5.6 | 6.2 6.7 6.5 | 7.0 9.4 8.2 | 5.2 8.1 6.7 | 3.7 4.1 3.9 | 1.7 2.0 1.8 | |
Non-extractable Residues | 1 2 | 0.3 0.1 | 1.6 0.6 | 1.8 1.6 | 3.0 3.2 | 8.8 10.8 | 24.6 16.3 | 13.2 26.3 | 34.6 44.9 | 31.9 35.4 | |
Mean | 0.2 | 1.1 | 1.7 | 3.1 | 9.8 | 20.4 | 19.8 | 39.7 | 33.7 | ||
Transformation Chamber Total Recovery | Mean | 110.5 | 101.0 | 100.7 | 98.6 | 98.2 | 78.2 | 60.7 | 68.7 | 48.6 | |
Material Balance 9 | Mean | 110.5 | 101.0 | 100.7 | 98.6 | 98.7 | 80.6 | 71.8 | 93.5 | 83.3 | |
n.a.: not analysed
1 sum of aqueous fraction and ethyl acetate fraction after partitioning of water
2 in ethyl acetate fraction after partitioning of water
3 region just above desmedipham in aqueous fraction after partitioning of water; a small peak was observed in this region for some samples.
4 Results from single samples rather than means
5 single values of water and sediment are summed up to total single values; mean values calculated from total single values
6 small peaks were observed in regions 2 and 3 for some samples. These peaks were usually broad and indistinct
7 non-retained or early eluting materials
8 sum of broad and indistinct radiodetection signals
9 Sum of radioactivity in transformation chambers (water and sediment) and mineralisation chambers
Mineralization test chambers were collected and processed at the end of the 101-day test. Each processed chamber yielded three samples: an aqueous fraction, a sediment extract, and solids remaining after extraction. The total 14C found in each sample was used to calculate the percent of dosed radioactivity. The total radioactivity found in each mineralization test chamber was calculated from the sum of the amounts found in the aqueous fractions, sediment extracts, solids remaining after extraction, and the cumulative total 14C-gasses. The mean material balances for all four test systems were > 90% AR.
Table 5: Mineralisation of [aniline-UL-14C]desmedipham in water/sediment system Turkey Creek (values expressed as % AR)
Matrix | Repl. No. | DAT | ||||||||||
7 | 14 | 21 | 28 | 35 | 49 | 63 | 77 | 91 | 101 | blanks | ||
CO2 | 1 2 Mean | 0.19 0.10 0.15 | 1.48 0.47 0.98 | 5.41 4.87 5.14 | 4.08 3.95 4.01 | 2.89 3.19 3.04 | 3.62 4.33 3.97 | 4.52 5.80 5.16 | 3.59 5.89 4.74 | 2.75 3.84 3.30 | 3.97 0.03 2.00 | 0.00 0.00 0.00 |
Sum | 0.15 | 1.13 | 6.27 | 10.28 | 13.32 | 17.29 | 22.45 | 27.19 | 30.49 | 32.49 | 32.49 | |
VOC | 1 2 Mean | 0.00 0.00 0.00 | 0.01 0.00 0.02 | 0.02 0.01 0.01 | 0.01 0.01 0.01 | 0.00 0.00 0.00 | 0.01 0.01 0.01 | 0.00 0.00 0.00 | 0.01 0.00 0.01 | 0.07 0.05 0.06 | 0.07 0.02 0.04 | 0.00 0.00 0.00 |
Sum | 0.00 | 0.02 | 0.03 | 0.04 | 0.04 | 0.05 | 0.05 | 0.06 | 0.12 | 0.16 | 0.16 | |
Total Volatiles | Mean Sum | 0.15 0.15 | 1.00 1.15 | 5.15 6.30 | 4.03 10.33 | 3.04 13.37 | 3.98 17.35 | 5.16 22.51 | 4.75 27.26 | 3.36 30.62 | 2.04 32.64 | 0.00 32.64 |
Table 6: Mineralisation of [aniline-UL-14C]desmedipham in water/sediment system Choptank River (values expressed as % AR)
Matrix | Repl. No. | DAT | ||||||||||
7 | 14 | 21 | 28 | 35 | 49 | 63 | 77 | 91 | 101 | blanks | ||
CO2 | 1 2 Mean | 0.44 0.59 0.51 | 1.07 2.68 1.87 | 1.85 3.84 2.85 | 3.07 8.63 5.85 | 2.42 6.66 4.54 | 3.19 7.07 5.13 | 2.90 5.06 3.98 | 2.82 4.15 3.49 | 3.90 0.52 2.21 | 2.72 0.03 1.36 | 5.39. 0.00 2.70 |
Sum | 0.51 | 2.38 | 5.23 | 11.08 | 15.62 | 20.75 | 24.74 | 28.22 | 30.43 | 31.79 | 34.49 | |
VOC | 1 2 Mean | 0.00 0.02 0.01 | 0.00 0.02 0.01 | 0.01 0.01 0.01 | 0.00 0.00 0.00 | 0.00 0.00 0.00 | 0.01 0.01 0.01 | 0.01 0.00 0.01 | 0.01 0.01 0.01 | 0.06 0.05 0.06 | 0.04 0.01 0.03 | 0.00 0.00 0.00 |
Sum | 0.01 | 0.02 | 0.03 | 0.03 | 0.03 | 0.04 | 0.05 | 0.06 | 0.12 | 0.15 | 0.15 | |
Total Volatiles | Mean Sum | 0.53 0.53 | 1.88 2.41 | 2.86 5.27 | 5.85 11.12 | 4.54 15.66 | 5.14 20.80 | 3.98 24.76 | 3.50 28.28 | 2.27 30.55 | 1.40 31.95 | 2.70 34.65 |
Table 1: Degradation of desmedipham in natural pond water under aerobic conditions (high concentration, single and mean values expressed as % AR_
Compound | Replicate | DAT | ||||||
0 | 1 | 3 | 7 | 14 | 30 | 62 | ||
desmedipham | (A) (B) | 101.2 100.7 | n.d. n.d. | n.d. n.d. | n.d. n.d. | n.d. n.d. | n.d. n.d. | n.d. n.d. |
Mean | 100.9 | n.d. | n.d. | n.d. | n.d. | n.d. | n.d. | |
diphenyl urea (M1) | (A) (B) | n.d. n.d. | n.d. n.d. | 16.9 19.0 | n.d. 6.4 | 3.6 4.4 | n.d. n.d. | n.d. n.d. |
Mean | n.d. | n.d. | 18.0 | 3.2 | 4.0 | n.d. | n.d. | |
aniline | (A) (B) | n.d. n.d. | 99.5 105.4 | 81.4 79.0 | 94.3 75.5 | 44.5 40.3 | 69.2 72.9 | 47.6 58.4 |
Mean | n.d. | 102.5 | 80.2 | 84.9 | 42.4 | 71.0 | 53.0 | |
Aqueous phase | (A) (B) | 101.2 100.7 | 99.5 105.4 | 98.3 98.0 | 94.3 81.9 | 48.1 44.7 | 69.2 72.9 | 47.6 58.4 |
Mean | 100.9 | 102.5 | 98.2 | 88.1 | 46.4 | 71.0 | 53.0 | |
Carbon dioxide | (A) (B) | n.p. n.p. | 0.1 0.1 | 0.1 0.2 | 0.9 1.2 | 2.3 1.8 | 1.9 2.7 | 4.0 6.0 |
Mean | n.p. | 0.1 | 0.2 | 1.0 | 2.0 | 2.3 | 5.0 | |
Other Volatiles | (A) (B) | n.p. n.p. | 0.5 2.7 | 2.8 3.3 | 5.2 15.6 | 47.1 52.0 | 27.8 24.0 | 51.5 36.4 |
Mean | n.p. | 1.6 | 3.0 | 10.4 | 49.5 | 25.9 | 43.9 | |
Total % Recovery* | (A) (B) | 101.2 100.7 | 100.1 108.2 | 101.2 101.5 | 100.4 98.6 | 97.4 98.5 | 99.0 99.7 | 103.0 100.8 |
Mean | 100.9 | 104.2 | 101.4 | 99.5 | 98.0 | 99.3 | 101.9 | |
n.d.: not detected; n.p.: not performed; DAT: days after treatment
Table 2: Degradation of desmedipham in natural pond water under aerobic conditions (sterile, high concentration, single values expressed as % AR)
Compound | DAT | ||||||
0 | 1 | 3 | 7 | 14 1 | 30 | 62 | |
desmedipham | 101.3 | n.d. | n.d. | n.d. | n.d. | n.d. | n.d. |
diphenyl urea (M1) | n.d. | n.d. | 8.3 | 17.2 | 5.9 | 3.4 | 6.5 |
aniline | n.d. | 99.3 | 78.6 | 80.7 | 46.8 | 76.3 | 58.4 |
Aqueous phase | 101.3 | 99.3 | 86.9 | 97.9 | 52.7 | 79.7 | 64.9 |
Carbon dioxide | n.p. | 0.1 | 0.1 | < 0.1 | 0.6 | 0.1 | 0.1 |
Other Volatiles | n.p. | 4.1 | 16.2 | 3.2 | 46.9 | 14.5 | 33.0 |
Total % Recovery | 101.3 | 103.5 | 103.1 | 101.1 | 100.2 | 94.3 | 98.0 |
n.d.: not detected; n.p.: not performed; DAT: days after treatment
1 between DAT-7 and DAT-14 the air flow through the high dose (sterile) test system was changed, resulting in an aberration of the DAT-14 values.
Table 3: Degradation of desmedipham in natural pond water under aerobic conditions (low concentration, single and mean values expressed as % AR)
Compound | Replicate | DAT | ||||||
0 | 1 | 3 | 7 | 14 | 30 | 62 | ||
| (A) | 99.8 | n.d. | n.d. | n.d. | n.d. | n.d. | n.d. |
desmedipham | (B) | 102.3 | n.d. | n.d. | n.d. | n.d. | n.d. | n.d. |
| Mean | 101.0 | n.d. | n.d. | n.d. | n.d. | n.d. | n.d. |
diphenyl urea (M1) | (A) (B) Mean | n.d. n.d. n.d. | n.d. n.d. n.d. | n.d. n.d. n.d. | n.d. n.d. n.d. | n.d. n.d. n.d. | n.d. n.d. n.d. | n.d. n.d. n.d. |
| (A) | n.d. | 94.5 | 94.4 | 80.6 | 48.4 | 50.7 | 48.0 |
aniline | (B) | n.d. | 99.2 | 93.4 | 82.6 | 57.5 | 39.6 | 34.7 |
| Mean | n.d. | 96.8 | 93.9 | 81.6 | 53.0 | 45.1 | 41.3 |
| (A) | 99.8 | 94.5 | 94.4 | 80.6 | 48.4 | 50.7 | 48.0 |
Aqueous phase | (B) | 102.3 | 99.2 | 93.4 | 82.6 | 57.5 | 39.6 | 34.7 |
| Mean | 101.0 | 96.8 | 93.9 | 81.6 | 53.0 | 45.1 | 41.3 |
| (A) | n.p. | 0.6 | 0.4 | 2.8 | 4.7 | 10.2 | 6.0 |
Carbon dioxide | (B) | n.p. | 0.4 | 0.7 | 2.6 | 5.1 | 3.6 | 4.4 |
| Mean | n.p. | 0.5 | 0.6 | 2.7 | 4.9 | 6.9 | 5.2 |
| (A) | n.p. | 2.2 | 0.3 | 12.1 | 45.8 | 40.6 | 42.5 |
Other Volatiles | (B) | n.p. | 1.8 | 5.3 | 13.6 | 35.2 | 57.0 | 60.1 |
| Mean | n.p. | 2.0 | 2.8 | 12.8 | 40.5 | 48.8 | 51.3 |
| (A) | 99.8 | 97.2 | 95.0 | 95.5 | 98.9 | 101.5 | 96.6 |
Total % Recovery* | (B) | 102.3 | 101.4 | 99.5 | 98.7 | 97.8 | 100.2 | 99.2 |
| Mean | 101.0 | 99.3 | 97.3 | 97.1 | 98.4 | 100.9 | 97.9 |
n.d.: not detected; n.p.: not performed; DAT: days after treatment
Table 3: Total system DT50 values for desmedipham and results of statistical evaluation of the reliable model fits for modelling purposes
Water/Sediment System | pH | Kinetic Model | DT50
[days] | DT90
[days] | Chi2 Error [%] | t-test probability | Visual
Assessment | |||
water | sediment | |||||||||
Curve | Residues | |||||||||
CMS pond (phenoxy) | 6.2 | 4.4 | SFO | 4.1 | 13.6 | 5.9 | < 0.001 | + | + | |
CMS pond (aniline) | 6.2 | 4.4 | FOMC | 3.5 1 | 11.6 | 5.6 |
| + | + | |
OCR pond (phenoxy) | 7.3 | 6.3 | SFO | 0.13 | 0.43 | 3.3 | < 0.001 | ++ | ++ | |
OCR pond (aniline) | 7.3 | 6.3 | SFO | 0.13 | 0.42 | 0.7 | < 0.001 | ++ | ++ | |
Illingen pond (phenoxy) | 7.7 | 7.7 | SFO | 0.052 | 0.17 | 1.5 | < 0.001 | ++ | ++ | |
Spiegelberg creek (phenoxy) | 8.1 | 7.5 | SFO | 0.050 | 0.17 | 2.4 | < 0.001 | ++ | ++ | |
Turkey Creek (aniline) | 5.6 | 5.6 | FOMC | 2.0 1 | 6.7 | 4.1 |
| ++ | ++ | |
Choptank River (aniline) | 7.1 | 7.1 | FOMC | 0.85 1 | 2.8 | 10.9 |
| + | + | |
OVP (phenoxy) | 8.14 | 7.6 | FOMC | 0.00321 | 0.011 | 1.7 |
| ++ | ++ | |
SW (phenoxy) | 9.05 | 7.4 | SFO | 0.055 | 0.18 | 6.7 | < 0.001 | ++ | ++ | |
Rhine River (aniline) | 8.2 | 7.26 | SFO | 0.035 | 0.12 | 0.5 | < 0.001 | ++ | ++ | |
Anwil pond (aniline) | 8.26 | 6.55 | SFO | 0.045 | 0.15 | 0.1 | < 0.001 | ++ | ++ | |
Arithmetic mean | 0.91 |
| ||||||||
Geometric mean | 0.16 | |||||||||
Median | 0.093 | |||||||||
1 derived from DT90 FOMC curve fit
Table 4: Total system DT50 values for desmedipham and results of statistical evaluation of the reliable model fits for persistence endpoints
Water/Sediment System | Kinetic Model | DT50 [days] | DT90 [days] | Chi2 Error [%] | t-test probability | Visual Assessment | |
Curve | Residues | ||||||
CMS pond (phenoxy) | SFO | 4.1 | 13.6 | 5.9 | < 0.001 | + | + |
CMS pond (aniline) | FOMC | 2.4 | 11.6 | 5.6 |
| ++ | + |
OCR pond (phenoxy) | SFO | 0.13 | 0.43 | 3.3 | < 0.001 | ++ | ++ |
OCR pond (aniline) | SFO | 0.13 | 0.42 | 0.7 | < 0.001 | ++ | ++ |
Illingen pond (phenoxy) | SFO | 0.052 | 0.173 | 1.5 | < 0.001 | ++ | ++ |
Spiegelberg creek (phenoxy) | SFO | 0.050 | 0.17 | 2.4 | < 0.001 | ++ | ++ |
Turkey Creek (aniline) | FOMC | 1.3 | 6.7 | 4.1 | n.a. | ++ | ++ |
Choptank River (aniline) | FOMC | 0.37 | 2.8 | 10.9 | n.a. | + | + |
OVP (phenoxy) | FOMC | 0.00022 | 0.011 | 1.7 | n.a. | ++ | ++ |
SW (phenoxy) | SFO | 0.055 | 0.183 | 6.7 | < 0.001 | ++ | ++ |
Rhine River (aniline) | SFO | 0.035 | 0.116 | 0.5 | < 0.001 | ++ | ++ |
Anwil pond (aniline) | SFO | 0.045 | 0.1 | 0.1 | < 0.001 | ++ | ++ |
Arithmetic mean | 0.72 |
| |||||
Geometric mean | 0.11 | ||||||
Median | 0.093 | ||||||
Table 1: Summary of the kinetic evaluation of the degradation of aniline labelled desmedipham in aerobic mineralisation test
Compound | kinetic model | M0 | ff | parameter | DT50 [days] | DT90 [days] | Chi2 [%] | prob > t |
Desmediphamhigh | SFO | 100.9 |
| k = 6.0010 | 0.004 | 0.01 | 0.4 | k: <<0.001 |
Anilinehigh | SFO |
| 1 (0.917 1) | k = 0.0545 | 75.9 | 252.1 | 6.1 | k: < 0.001 |
Anilinelow 2 | SFO |
| 0.916 | k = 0.0192 | 34.9 | 115.9 | 11.8 | k: < 0.001 |
Diphenyl ureahigh | SFO |
| 0.080 | k = 0.0091 | 12.8 | 42.4 | 111.5 | k: 0.2313 |
Diphenyl ureahigh | SFO | 17.9 | 0.083 3 | k = 0.2574 | 2.7 4 | 8.9 4 | 1.5 4 | k: < 0.001 4 |
Desmediphamlow | SFO | 101.0 |
| k = 5.944 | 0.12 | 0.39 | 0.02 | k: 0.009 |
Study conclusion (Chapple and Heruth, 2014):
Desmediphamhigh SFO: fit visually (2 data points) and statistically acceptable (X2 0.4 %) (comment RMS: agreed) Anilinehigh SFO: fit visually (2 data points) and statistically acceptable (X2 6.1 %) (comment RMS: agreed) Anilinelow SFO: fit visually and statistically acceptable (X2 9.2 %) Diphenyl ureahigh SFO: fit visually and not statistically acceptable (X2 111.5 %) (comment RMS: residual plot show too high variability) Diphenyl ureahigh SFOmax onwards: fit visually and statistically acceptable (X2 1.5 %) (comment RMS: agreed) Desmediphamlow SFO: fit visually (2 data points) and statistically acceptable (X2 0.02 %) (comment RMS: agreed) | ||||||||
1 calculated from 1 - FF of diphenyl urea
2 the visual assessment for aniline was better using the DFOP model but as the statistical fit was not significantly better than with SFO it was decided to choose SFO kinetics
3 estimated from pathway fit
4 estimated from decline curve of metabolite from maximum occurrence onwards (SFO)
Description of key information
The half life in freshwater is based on the low concentration aerobic mineralisation study and the half life in freshwater sediment is based on a total system median value from five water/sediment studies (see Chapple and Heruth (2014) for full table of kinetics).
Both values are based on the modelling endpoints (following FOCUS guidance).
In the table below all available studies are listed. For some studies only the results are presented since they are not considered relevant due to the reasons given under “Assessment”. All available studies have been evaluated within the scope of Plant Protection Regulation in the respective Draft Renewal Assessment Report (DAR) under Regulation (EC) 1107/2009.
| Test type | Result | Assessment | Reference |
| Carried out following OECD 308 guidelines in two water/sediment systems | Desmedipham decreased to 4.2 - 1.5% AR in two water sediment total systems. DT50 values 0.85 to 2.0 days (at 20°C) | Key study | Schaefer and Stenzel (2006) |
| OECD 309 Aerobic mineralisation test | Desmedipham degraded rapidly in natural surface water (within 24 hours) | Key study | Adam (2014) |
| Kinetics report carried out in line with FOCUS guidelines | DT50 values of 0.004 and 0.12 days in high and low concentration systems, respectively at 21 °C. Key value of 0.28 days at 12 °C. | Key study | Chapple and Heruth (2014) |
| Carried out following FOCUS guidelines | Total system degradation DT50 0.093 days (20 °C) | Key study | Chapple (2016) |
| Carried out following BBA guidelines | Rapid degradation shown with DT50 < 1 day (20 °C) | Supporting study | Seyfried (1995) |
| Carried out following EPA/SETAC guidelines | Rapid partitioning and degradation shown DT values 0.1 to 4 days (20 °C). | Supporting study with further metabolite identification work carried out under Andre (2003) | Sabourin (2003) |
| Position paper | Rapid partitioning and degradation shown DT values 0.1 to 4 days (20 °C). | Position paper relating to Sabourin (2003) | Burr (2003) |
| Carried out following SETAC guidelines | Rapid degradation shown with DT50 < 1 day (at 20 °C) | Supporting study | van Noorloos (2003) |
| Guidance not stated but in line with OECD 308 | Rapid degradation shown with DT50 < 1 day (at 20 °C) | Supporting study | Heintze (2003) |
| Degradation of desmedipham in a sediment/water microecosystem | No result specified. | The study was not considered valid in DAR due to many deficiencies in the study (material balance not acceptable, water properties not given, no information, whether study was performed in dark conditions). | Forster (1991) |
| Kinetic evaluation in water/sediment | No result specified. | Superseded kinetics- not required | Schaefer (2003) |
| Anaerobic aquatic behavior in a simulated sediment / water ecosystem | No result specified. | Anaerobic conditions and not considered to be valid in the DAR | Forster (1991) |
| Supplemental work | Phenol was identified as a metabolite from the water/sediment study of Sabourin (2003). | Metabolite identification work from study Sabourin (2003). | Andre (2003) |
Persistence Assessment
In the OECD 309 aerobic mineralisation study in surface water the amount of non-extractible residues can be assumed to be negligible (based on total mean recoveries of > 100.7 and 100.2 % AR for the high dose and low dose respectively). So, the calculated DT50 value for desmedipham (of 0.28 days at 12 oC) can be assumed to reflect true degradation. However, the breakdown products also need consideration. When converted to 12 oC the aniline metabolite has a DT50 of 81.1 days and the diphenyl urea has a DT50 of 6.3 days.
This compares against a persistence (P) cut off value of > 40 days in fresh water or a very persistent (vP) cut off value of > 60 days in fresh water. So, although desmedipham breaks down rapidly- it must be considered as being vP due to the aniline metabolite.
For the sediment compartment, degradation kinetics for the total water/sediment system are compared against the trigger values.
The DT50 values quoted in the study and kinetics report (taken from the crop protection dossier) do not take the non-extracted residues (NER) into account, so cannot be directly compared to the P- and vP-criteria. Looking at the amount of NER, it can be seen that they increased during the study reaching maximum levels of 33.7- 48.5 % AR at the end of the study (on day 100). However, when the NER is considered to be the parent compound and values are added to the concentration of desmedipham , acceptable DT50 values (following FOCUS guidance) cannot be calculated due to the rising levels of NER at the end of the study.
Alternatively, in the key study M-493999-01-1, the mineralisation was measured in two water/sediment systems up to 101 days. Using these values mineralisation DT50 values of 164 days (Turkey SFO) and 180 days (Choptank SFO) can be calculated at test temperature. When converted to 12 oC this gives a mean value of > 365 days which is greater than the trigger value of > 120 days (P) or > 180 days (vP) for freshwater sediment.
Key value for chemical safety assessment
- Half-life in freshwater:
- 0.28 d
- at the temperature of:
- 12 °C
- Half-life in freshwater sediment:
- 0.16 d
- at the temperature of:
- 12 °C
Additional information
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