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EC number: 266-096-3 | CAS number: 66063-05-6
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Adsorption / desorption
Administrative data
Link to relevant study record(s)
- Endpoint:
- adsorption / desorption: screening
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 1989-02-27
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- guideline study with acceptable restrictions
- Qualifier:
- according to guideline
- Guideline:
- other: US FIFRA N-163-1 40 CFR, Sec. 158.130 & 158.50
- Deviations:
- yes
- Remarks:
- The history of the soil with respect to the use of pesticides is not given.
- GLP compliance:
- yes (incl. QA statement)
- Remarks:
- Good laboratory practice requirements of 40 CFR Part 160 do not apply to the study described.
- Type of method:
- batch equilibrium method
- Media:
- soil
- Radiolabelling:
- yes
- Test temperature:
- 25°C
- Analytical monitoring:
- yes
- Details on sampling:
- - Concentrations: 0.0179, 0.0915, 0.143 and 0.186 mg/L
- Sampling interval: 0, 4, 6, 8, 16, 24, 36, 48 hours
- Sample storage before analysis: refrigerated - Details on matrix:
- Four soils were used; the soil characterisation is given in Table 1.
The history of the soil with respect to the use of pesticides is not given. The appropriate soil to water ratio for the four soils was determined in a preliminary study. In the definitive test, each soil experiment was performed in duplicate at four test substance concentrations (measured concentrations 0.0179, 0.0915, 0.143 and 0.186 mg/L). - Details on test conditions:
- TEST CONDITIONS
- pH: 6.96 - 7.51
TEST SYSTEM
- Type, size and further details on reaction vessel: Ten-mL Pyrex culture tubes with teflon lined screw caps were used as sample containers. The culture tubes and caps were sterilized by autoclaving at 250°F and 15 psi for one hour.
- Water filtered (i.e. yes/no; type of size of filter used, if any): Yes, 0.22 micron filter.
- Amount of soil: 1 g
- Number of reaction vessels: Two replicates each of the four soil types were sampled
The test substance was dosed (after evaporation from the solvent) from a 0.01M CaCl2 solution in sterile culture tubes, each containing one gram (dry weight) of soil. The soil suspensions were shaken in the dark, on a mechanical shaker, in an environmental controlled room (temp = 25 ± 2ºC) for six hours. Subsequently, the vessels were centrifuged and the supernatant was removed and the volume was recorded. The radioactivity of the supernatant was determined in triplicate by LSC analysis and the stability of the compound by TLC. For desorption purposes, appropriate volumes of fresh 0.01M CaCl2 solution (equal to the amount removed after centrifugation) were added to each sample and soil suspensions were shaken for 24h and subsequently treated similar as during the adsorption process. At the end of the test the remaining soil was extracted to characterize the adsorbed 14C activity in the soil. - Key result
- Sample No.:
- #1
- Type:
- Kd
- Value:
- 55 L/kg
- Temp.:
- 25 °C
- Matrix:
- sand
- % Org. carbon:
- 0.526
- Remarks on result:
- other: KFoc: 10441, 1/n:1.1770
- Key result
- Sample No.:
- #2
- Type:
- Kd
- Value:
- 28.4 L/kg
- Temp.:
- 25 °C
- Matrix:
- Sandy loam
- % Org. carbon:
- 0.577
- Remarks on result:
- other: KFoc: 4912, 1/n: 1.0519
- Key result
- Sample No.:
- #3
- Type:
- Kd
- Value:
- 36.9 L/kg
- Temp.:
- 25 °C
- Matrix:
- Silt loam
- % Org. carbon:
- 1.53
- Remarks on result:
- other: KFoc: 2414, 1/n: 0.9058
- Key result
- Sample No.:
- #4
- Type:
- Kd
- Value:
- 56.7 L/kg
- Temp.:
- 25 °C
- Matrix:
- Clay loam
- % Org. carbon:
- 1.16
- Remarks on result:
- other: KFoc: 4899, 1/n: 1.2058
- Recovery of test material:
- The total radioactivity recoveries for sand, sandy loam, silt loam and clay loam were 106%, 91.7%, 103% and 106%. The equilibrium pH of the adsorption phase, as measured in each sample, varied between 6.96 and 7.51. LSC analysis of a duplicate control containing the aqueous test solution without soil, in the preliminary test, showed that there was no adsorption to the glass walls of the test tubes.
- Concentration of test substance at end of adsorption equilibration period:
- At the end of the adsorption phase, the percentage Pencycuron in the soil extracts was 64.2, 67.8, 51.9 and 73.5 after six hours equilibration in sand, sandy loam, silt loam and clay loam, respectively.
- Concentration of test substance at end of desorption equilibration period:
- After desorption the percentage Pencycuron in the soil extracts was 85.0, 92.5, 87.3 and 84.6, showing that Pencycuron is weekly desorbed.
- Details on results (Batch equilibrium method):
- PRELIMINARY TEST
- Other: 1 to 10 soil to water ratio with an equilibrium time of 6 hours were the appropriate difinitive study parameters for all four soil types.
MAIN TEST: PERFORMANCE
The adsorption constants Kd and Koc, as calculated from the Freundlich isotherms for the four soils, ranged from 28.4 to 56.7 L/kg and 2414 to 10441 L/kg, respectively. The desorption values were from 48.2 to104 L/kg and from 5560 to 19829 L/kg, respectively. The results of the test as adsorption and desorption coefficients and the Freundlich constants 1/n are summarized in Table 2. - TLC of the 2 mg/L test solution at test inititation (pencycuron represented 89.7% of the radioactivity) and after equilibration (pencycuron represented 64.2%, 67.8%, 51.9% and 73.5% of the radioactivity in sand, sandy loam, silt loam and clay loam, respectively) showed that pencycuron was not stable in the test solution. TLC of soil extracts from post-desorbed soils showed that in extracts of sand, sandy loam, silt loam and clay loam, respectively, pencycuron represented 85.0%, 92.5%, 87.3% and 84.6% of the radioactivity. The amount of test material adsorbed to soil was calculated as the difference between the amount of radioactivity present in the adsorption solution after adsorption and that initially added to each tube. Since this method involves no correction for degradation in the aqueous phase, the amount of pencycuron adsorbed to soil was underestimated by this method, and the equilibrium concentration of pencycuron overestimated, hence the adsorption coefficients are underestimated. Although there is some doubt about the accuracy of the reported Freundlich adsorption coefficients, they are accepted as worst case values.
- Sorption in these four soils was not related to soil organic carbon content (linear regression analysis of the KF values versus % oc gave r2 = 0002), and also not to soil pH (r2 = 0.26 for plot of KF values versus soil pH) or clay content (r2 = 0.03 for plot of KF values versus percentage clay).
- Validity criteria fulfilled:
- yes
- Remarks:
- Minor deviations; Some degradation was observed in the study, so underestimates the adsorption to soil. These were accepted as being worst case values. The history of the soil with respect to the use of pesticides is not given. The study was accepted.
- Conclusions:
- The adsorption constants Kd and Koc, as calculated from the Freundlich isotherms for the four soils, ranged from 28.4 to 56.7 L/kg and 2414 to 10441 L/kg, respectively. The desorption values were from 48.2 to104 L/kg and from 5560 to 19829 L/kg, respectively. 1/n ranged from 1.0615 to 1.2078.
- Executive summary:
The adsorption/desorption test was performed with the radio-labelled active substance [methylene-14C]Pencycuron using 4 soils, sand, sandy loam, silt loam and a clay loam.
each soil experiment was performed in duplicate at four test substance concentrations (measured concentrations 0.0179, 0.0915, 0.143 and 0.186 mg/L). The test substance was dosed (after evaporation from the solvent) from a 0.01M CaCl2 solution in sterile culture tubes, each containing one gram (dry weight) of soil. The soil suspensions were shaken in the dark, on a mechanical shaker, in an environmental controlled room (temp = 25 ± 2ºC) for six hours. Subsequently, the vessels were centrifuged and the supernatant was removed and the volume was recorded. The radioactivity of the supernatant was determined in triplicate by LSC analysis and the stability of the compound by TLC.
Following the desorption soils were extracted to charaterize adsorbed radioactivity in the soil.
Reference
Table 2: Adsorption and desorption coefficients of Pencycuron in four soils
Soil type | % organic carbon | adsorption in | L/kg | desorption | |||
Kd | KFoc | 1/n | Kd | Koc | 1/n | ||
sand | 0.526 | 55.0 | 10441 | 1.1770 | 104 | 19829 | 1.2078 |
sandy loam | 0.577 | 28.4 | 4912 | 1.0519 | 48.2 | 8329 | 1.0709 |
silt loam | 1.53 | 36.9 | 2414 | 0.9058 | 99.6 | 6526 | 1.0615 |
clay loam | 1.16 | 56.7 | 4899 | 1.2058 | 64.4 | 5560 | 1.1173 |
Description of key information
The calculated KFoc(ads) values varied between 2414 and 10441 L/kg (median value: 4906 L/kg). The Freundlich exponents 1/n were in the range of 0.9058 to 1.1770.
Test Type | Result | Assessment | Reference |
Batch adsorption study to US FIFRA N-163-1 guidelines | KFoc range 2414 to 10441 L/kg (median value of 4906 L/kg) reported with 1/n of 0.9058 to 1.1770. Some deficiencies in study- but accepted as providing worst case values. | Key study | Daly (1989) |
Key value for chemical safety assessment
- Koc at 20 °C:
- 4 906
Additional information
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