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EC number: 240-815-0 | CAS number: 16752-77-5
- 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
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Hydrolysis
Administrative data
Link to relevant study record(s)
- Endpoint:
- hydrolysis
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- guideline study without detailed documentation
- Qualifier:
- according to guideline
- Guideline:
- other: U.S. EPA Subdivision D, 63-13
- Deviations:
- no
- GLP compliance:
- no
- Specific details on test material used for the study:
- - Substance name: Methomyl
- Purity: Not reported - Radiolabelling:
- no
- Analytical monitoring:
- no
- Buffers:
- - pH: 5, 7, 9
- Duration:
- 30 d
- pH:
- 5
- Duration:
- 30 d
- pH:
- 7
- Duration:
- 30 d
- pH:
- 9
- Number of replicates:
- One
- Positive controls:
- no
- Negative controls:
- no
- Transformation products:
- not measured
- Key result
- pH:
- 9
- DT50:
- 30 d
- Key result
- Remarks on result:
- other: The test substance was stable in sterile distilled water for 30 days at pH 5 and 7
- Validity criteria fulfilled:
- not specified
- Conclusions:
- The test substance was stable in sterile distilled water for 30 days at pH 5 and 7, but decomposed with a half-life of 30 days at pH 9.
- Executive summary:
The objective of the study was to determine the stability of the test substance in sterile distilled water at pH levels of 5, 7 and 9, following the guideline U.S. EPA 63-13.
The test substance was stable in sterile distilled water for 30 days at pH 5 and 7, but decomposed with a half-life of 30 days at pH 9.
- Endpoint:
- hydrolysis
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 111 (Hydrolysis as a Function of pH)
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EPA OPPTS 835.2120 (Hydrolysis of Parent and Degradates as a Function of pH at 25°C)
- Deviations:
- no
- GLP compliance:
- yes
- Specific details on test material used for the study:
- Purity: 99.8%
- Radiolabelling:
- yes
- Analytical monitoring:
- yes
- Details on sampling:
- - Sampling intervals:
pH 4 and 7, 30 and 40 °C: Days 0, 3, 7, 14, 21, 25, 28, 31
pH4 60 °C: Days 0, 1, 3, 4, 8, 11, 15, 18, 31
pH7 60 °C: Days 0, 0.9, 1.2, 2, 3, 4, 7, 8, 11
pH9 25 °C: Days 0, 1, 2, 5, 7, 16, 21, 30
pH9 35 °C: Days 0, 0.8, 1, 2, 3, 4, 6, 7, 12
pH9 45 °C: Days 0, 0.1, 0.2, 0.3, 0.5, 1, 1.3, 2, 3
- Sampling method: The test system solutions were aliquoted from the volumetric flasks to HPLC vials and analyzed directly by HPLC. Individual vials were removed from incubation at each time point; 1-mL aliquots of the test solution were removed, added to HPLC vials and analyzed by HPLC directly.
- Sampling intervals/times for pH: The pH of each buffer solution was measured at the time of preparation. The pH of each test sample solution was measured after addition of the test substance and at the end of the hydrolysis testing.
- Sampling intervals/times for sterility check: At the initiation and termination of all tests, sterility of the test solutions was verified using 3M™ Petrifilm™, with the exception of initiation of the pH 9 tests at 25 °C and 35 °C, and the termination of the pH 7 at 60 °C test. An aliquot of each test solution (1 mL) was applied on a Petrifilm™ and incubated at 30 °C for at least 3 days following completion of the experimental test. The incubated Petrifilms™ were counted for potential contaminated biological species. Microbial enumeration to show sterility was not completed at initiation of the pH 9 tests at 25 °C and 35 °C, or the termination of the pH 7 at 60 °C test. Sterility testing was completed at termination for the pH 9 tests and showed sterility under the test conditions. For the pH 7, 60 °C test, the termination samples were removed from storage (freezer) and microbial enumeration was performed and showed sterility. In these cases, sterility was shown after the end of the study showing no contamination of the samples. Therefore, there was no negative impact due to this deviation.
- Sample storage conditions before analysis: All samples were analyzed on the sampling day when possible. Samples were stored frozen after the initial analysis. - Details on test conditions:
- A preliminary test (Tier 1) was conducted. A [14C]methomyl stock solution was prepared by adding 29 μL of R-12438-A (MM-12445-00001) to a 25-mL volumetric flask and bringing the flask volume with 0.01 M pH 4 buffer. This solution was given the ABC designation of R-12445-A with a concentration of 1.15 mg/L. A [14C]methomyl stock solution was prepared by adding 29 μL of R-12438-A (MM-12445-00001) to a 25-mL volumetric flask and bringing the flask volume with 0.01 M pH 7 buffer. This solution was given the ABC designation of R-12445-B with a concentration of 1.09 mg/L. The preliminary test was conducted from 24 June to 29 June 2015 at pH 4 and pH 7. Greater than 10% hydrolysis of the test substance was observed at both pHs; therefore, a Tier 2 definitive test was conducted.
For the Definitive test (Tier 2) Test solutions were prepared by adding aliquots of the 849.0 μg/mL stock solution to volumetric flasks. The flasks were then brought to volume with the appropriate buffer. If necessary, the stock solution was concentrated under nitrogen so the amount of organic solvent in all test solutions was ≤ 0.5%. These test solutions were then aliquoted with no headspace into individual autoclaved amber borosilicate vials with sterilized PTFE lined caps. The individual hydrolysis test vessels were wrapped in aluminum foil and placed into the appropriate incubators. On Day 0, the test system solutions were aliquoted from the volumetric flasks to HPLC vials and analyzed directly by HPLC. Individual vials were removed from incubation at each time point; 1-mL aliquots of the test solution were removed, added to HPLC vials and analyzed by HPLC directly. When sampling was complete, the amber test sample vials were stored frozen. The sampling schedule was described above.
Identification of hydrolysis products (Tier 3) was conducted. Metabolites were chromatographically separated and assigned by HPLC by comparing retention times with authentic reference standards. High-performance liquid chromatography/ultra-violet detection (HPLC/UV) analysis using a different column packing material was used as the confirmatory method. - Duration:
- 31 d
- pH:
- 4
- Temp.:
- 30 °C
- Duration:
- 31 d
- pH:
- 4
- Temp.:
- 40 °C
- Duration:
- 31 d
- pH:
- 4
- Temp.:
- 60 °C
- Duration:
- 31 d
- pH:
- 7
- Temp.:
- 30 °C
- Duration:
- 31 d
- pH:
- 7
- Temp.:
- 40 °C
- Duration:
- 31 d
- pH:
- 7
- Temp.:
- 60 °C
- Duration:
- 30 d
- pH:
- 9
- Temp.:
- 25 °C
- Duration:
- 12 d
- pH:
- 9
- Temp.:
- 35 °C
- Duration:
- 3 d
- pH:
- 9
- Temp.:
- 45 °C
- Number of replicates:
- 2
- Positive controls:
- no
- Statistical methods:
- Mean results were calculated from the results of individual replicates. Where assessment of the variability within replicates was required, mainly for analytical data, coefficients of variance were calculated.
- Preliminary study:
- In the preliminary experiment, methomyl was shown to be hydrolytically unstable at pH 4 and 7, and prior information about the hydrolysis of the test substance at pH 9 led to all pH levels being tested in the definitive experiment.
- Transformation products:
- yes
- No.:
- #1
- No.:
- #2
- Details on hydrolysis and appearance of transformation product(s):
- Degradation in all pH buffers proceeded primarily via hydrolysis of the carbamate ester of methomyl to form IN-X1177 and then the formation of acetonitrile (ACN).
- Key result
- pH:
- 4
- Temp.:
- 30 °C
- Hydrolysis rate constant:
- 0.002 d-1
- DT50:
- 319 d
- Type:
- (pseudo-)first order (= half-life)
- Key result
- pH:
- 4
- Temp.:
- 40 °C
- Hydrolysis rate constant:
- 0.007 d-1
- DT50:
- 100 d
- Type:
- (pseudo-)first order (= half-life)
- Key result
- pH:
- 4
- Temp.:
- 60 °C
- Hydrolysis rate constant:
- 0.079 d-1
- DT50:
- 8.79 d
- Type:
- (pseudo-)first order (= half-life)
- Key result
- pH:
- 7
- Temp.:
- 30 °C
- Hydrolysis rate constant:
- 0.003 d-1
- DT50:
- 273 d
- Type:
- (pseudo-)first order (= half-life)
- Key result
- pH:
- 7
- Temp.:
- 40 °C
- Hydrolysis rate constant:
- 0.014 d-1
- DT50:
- 50 d
- Type:
- (pseudo-)first order (= half-life)
- Key result
- pH:
- 7
- Temp.:
- 60 °C
- Hydrolysis rate constant:
- 0.25 d-1
- DT50:
- 2.81 d
- Type:
- (pseudo-)first order (= half-life)
- Key result
- pH:
- 9
- Temp.:
- 25 °C
- Hydrolysis rate constant:
- 0.051 d-1
- DT50:
- 13.7 d
- Type:
- (pseudo-)first order (= half-life)
- Key result
- pH:
- 9
- Temp.:
- 35 °C
- Hydrolysis rate constant:
- 0.25 d-1
- DT50:
- 2.77 d
- Type:
- (pseudo-)first order (= half-life)
- Key result
- pH:
- 9
- Temp.:
- 45 °C
- Hydrolysis rate constant:
- 0.94 d-1
- DT50:
- 0.734 d
- Type:
- (pseudo-)first order (= half-life)
- Validity criteria fulfilled:
- yes
- Conclusions:
- Methomyl was unstable at all pH and temperature conditions; however, hydrolysis occurred at a more rapid rate at higher temperatures across the pH range tested. Based on these results, methomyl would be expected to hydrolyze in the environment.
- Executive summary:
The hydrolysis of [14C] methomyl was studied in sterile aqueous solutions buffered at pH 4 (0.01 M phthalate), 7 (0.01 M phosphate), and 9 (0.01 M borate). The tests were conducted at three different temperatures: pH 4 and 7 (30°C, 40°C, and 60°C) and pH 9 (25°C, 35°C, and 45°C). The concentration of the test substance was 0.947 to 1.15µg/mL (approximately 1 ppm (or mg/L)). In the preliminary experiment, methomyl was shown to be hydrolytically unstable at pH 4 and 7, and prior information about the hydrolysis of the test substance at pH 9 led to all pH levels being tested in the definitive experiment. Buffer solutions at pH 4, 7, and 9 were fortified with test substance, incubated at temperatures ranging from 25 to 60 °C, and analyzed at various intervals by High Performance Liquid Chromatography (HPLC) with an in-line radiochemical detector and liquid scintillation counting (LSC).
The material balance was quantitative for all samples and was in the range of 89.8 to 106.6% applied radioactivity (% AR).
Degradation in all pH buffers proceeded primarily via hydrolysis of the carbamate ester of methomyl to form IN-X1177 and then the formation of acetonitrile (ACN). Methomyl and metabolites, IN-X1177 and ACN, were assigned by comparison of the HPLC retention times with respective reference standards. ACN was confirmed through a secondary HPLC method, as well as through volatilization experiments.
The percentage of parent methomyl was plotted against time for each pH level and temperature, and the DT50values were determined using SFO (single first order) kinetics, which displayed a good fit to the data. At pH 4, the DT50 values were 319, 100, and 8.79 days at 30, 40, and 60°C, respectively. At pH 7, the DT50 values were 273, 50.0, and 2.81 days at 30, 40, and 60°C, respectively. At pH 9, the DT50 values were 13.7, 2.77, and 0.734 days at 25, 35, and 45°C, respectively.
This study demonstrated that methomyl was unstable at all pH and temperature conditions; however, hydrolysis occurred at a more rapid rate at higher temperatures across the pH range tested. Based on these results, methomyl would be expected to hydrolyze in the environment.
Referenceopen allclose all
pH | Temperature (degC) | Maximum Amount of Metobilte Detected at Teimpoint (expressed as % AR) | |
IN-X1177 | ACN | ||
4 | 30 | 4.1 (Day 31) | 3.3 (Day 28) |
4 | 40 | 11.6 (Day 31) | 7.4 (Day 28) |
4 | 60 | 41.2 (Day 18) | 36.3 (Day 31) |
7 | 30 | 11.3 (Day 31) | 1.4 (Day 14) |
7 | 40 | 36.0 (Day 31) | 1.6 (Day 25) |
7 | 60 | 90.7 (Day 11) | 1.6 (Day 7) |
9 | 25 | 78.2 (Day 30) | 1.5 (Day 16) |
9 | 35 | 94.1 (Day 12) | 1.5 (Day 3) |
9 | 45 | 92.9 (Day 3) | 1.5 (Day 0.2) |
Description of key information
Study Type |
Study Details | Value | Guideline | Reliability |
Hydryolysis | Tested at pH 5 and pH 9 |
Stable at pH = 5 DT50 = 30 days at pH = 9 |
EPA 63-13 |
2 |
Hydrolysis | Tested at pH 5, 7, and 9 | Unstable at all pH and temperature conditions. Hydrolysis occurred at a more rapid rate at higher temperatures across the pH range tested. pH 4, the DT50 values were 319, 100, and 8.79 days at 30, 40, and 60°C, respectively. pH 7, the DT50 values were 273, 50.0, and 2.81 days at 30, 40, and 60°C, respectively. pH 9, the DT50 values were 13.7, 2.77, and 0.734 days at 25, 35, and 45°C, respectively |
OECD 111 OPPTS 835.2120 |
1 |
Key value for chemical safety assessment
- Half-life for hydrolysis:
- 273 d
- at the temperature of:
- 30 °C
Additional information
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.
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