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EC number: 402-140-1 | CAS number: 17865-32-6 CHMMS; CHMS; DYNASYLAN 9407; Z-6187
- 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
![](https://echa.europa.eu/o/diss-blank-theme/images/factsheets/A-REACH/factsheet/print_ecotoxicological-information.png)
Toxicity to microorganisms
Administrative data
Link to relevant study record(s)
- Endpoint:
- activated sludge respiration inhibition testing
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 1997-05-12 to 1997-05-16
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
- GLP compliance:
- yes
- Details on test solutions:
- Test article amounts of 49, 26, 12, 6 and 3 mg were weighed and ejected into 1000-ml brown glass flasks, filled with 284 ml of deionised water and stirred. Stirring continued for 30 hours.
- Test organisms (species):
- activated sludge of a predominantly domestic sewage
- Details on inoculum:
- Activated sludge from a domestic wastewater treatment plant (ARA Ergolz II, Fullinsdorf/Switzerland).
Washed by centrifugation, supernatant decanted, solid material resuspended.
Dry weight of activated sludge 4 g/l. - Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 3 h
- Post exposure observation period:
- Oxygen consumption measured over a period of up to ten minutes (Winkler flasks and oxygen electrode)
- Test temperature:
- 22°C
- Nominal and measured concentrations:
- 6, 12, 24, 50 and 100 mg/l nominal.
- Reference substance (positive control):
- yes
- Remarks:
- 3, 5-Dichlorophenol
- Key result
- Duration:
- 3 h
- Dose descriptor:
- EC50
- Effect conc.:
- > 100 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- inhibition of total respiration
- Remarks:
- respiration rate
- Details on results:
- In comparison to the inoculum controls the respiration rate of the activated sludge was not inhibited at nominal concentrations of 6, 12, 24, 50 and 100 mg/l. Based on the appearance of test substance in the deionised water by visual assessment after 30 minutes of stirring, but prior to addition of synthetic sewage feed and activated sludge, and obvious excess of test article was present in all test flasks bu the test article droplets were generally finely distributed. EC50 and EC20 values are clearly higher than the limit of water solubility of the substance under the present conditions, or >100 mg/l nominal.
- Results with reference substance (positive control):
- 3hr EC50 19.6 mg/l
- Validity criteria fulfilled:
- yes
- Conclusions:
- An activated sludge respiration inhibition 3hr EC50 value of >100 mg/l (nominal) was determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.
- Endpoint:
- activated sludge respiration inhibition testing
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
- Deviations:
- yes
- Remarks:
- Minor deviations only. These did not affect the integrity or outcome of the study.
- GLP compliance:
- yes (incl. QA statement)
- Analytical monitoring:
- no
- Vehicle:
- no
- Details on test solutions:
- Owing to the limited water solubility of the substance the solutions for both the range-finder and definitive tests were prepared by direct addition of the substance to the vessels containing mixtures of reverse-osmosis water and synthetic sewage. These solutions were ultrasonicated for approximately 10 minutes in order to attempt to disperse the test substance as an emulsion prior to adding the inoculum.
For the range finding test the following four concentrations of DCPMS were tested (each tested in duplicate): 1.0, 10, 100 and 1,000 mg/l.
For the definitive test the following five concentrations of DCPMS were tested (each tested in duplicate): 1,000, 2,000, 5,000, 10,000 and 20,000 mg/l.
Observations during the definitive test indicated that the test substance tended to spread as an oily film over the surface of the solution during ultrasonication and that only partial emulsification was noted at the two highest concentrations tested of 10,000 and 20,000 mg/l.
3,5-Dichlorophenol was used as a reference inhibitor. A stock solution of this substance was prepared by dissolving 0.125 g in 250 ml of reverse-osmosis water before use. The reference inhibitor was tested at conentrations of 5, 15 and 45 mg/l (single replicates of each) in both the range finding test and the definitive test).
Two separate 1 litre batches of 100-fold OECD synthetic sewage concentrate were prepared. The first batch was used to feed the inoculum before and after the range finding test and to provide the substrate for the test mixtures in the range finding test. The second batch was used to feed the inoculum once in the period between the range finding test and the definitive test and also in the definitive test.
For the range finding test, the incubations were started sequentially at timed intervals by adding 200 ml inoculum to 300 ml of the aqeuous solutions containing the DCPMS and synthetic sewage (16 ml). The controls consisted of 200 ml inoculum added to 300 ml in reverse-osmosis water containing 16 ml synthetic sewage. The reference substance solutions were similarly prepared with the appropriate volumes of 3,5-dichlorophenol stock solution.
For the definitive test, the test solutions were prepared in the same way but, owing to the limited amount of test substance available, all volumes were halved (a final volume of 250 ml rather than 500 ml was used). - Test organisms (species):
- activated sludge of a predominantly domestic sewage
- Details on inoculum:
- The activated sludge sample was collected from a return sludge channel at a sewage treatment works treating predominantly domestic waste water. On arrival at the laboratory the sludge sample was continually aerated prior to use.
The inoculum was prepared by dilution of the activated sludge sample in tap water to give a total volume of 8 litres with a dry suspended solids concentration of around 4 g/l. The inoculum was not acclimatised or adapted to the test substance before use in the test.
Once prepared the inoculum was maintained by feeding overnight with 100-fold OECD synthetic sewage conceentrate at a rate of 50 ml/l prior to the rangefinding test. The inoculum was used in the range finding test on the day after collection and was kept continually aerated throughout this period.
The suspended solids concentration of the inoculum was re-determined immediately prior to the definitive test and a subsample was adjusted (diluted) with dechlorinated tap water to give a suspended solids contents of 4 g/l. The pH of the inoculum was determined to be 7.49 which is within the permitted range of the test and so the inoculum was used without further pH adjustment. - Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 3 h
- Hardness:
- Reverse-osmosis water used.
- Test temperature:
- The temperature during the tests was in the range 20.2 to 21.7°C which is within the range of 20 +/- 2 °C required in the Test Guideline.
- Nominal and measured concentrations:
- The nominal concentrations of DCPMS were 1.0, 10, 100 and 1,000 mg/l in the range-finder test and 1,000, 2,000, 5,000, 10,000 and 20,000 mg/l in the definitive test.
- Details on test conditions:
- The test solutions were incubated for 3 hours with aeration. At the end of the incubation period, sub-samples of each solution were used for dissolved oxygen measurements. For this a portion of the test mixture was transfered to fill a 250 ml sampling bottle containing a magnetic stirrer bar. A dissolved oxygen probe was then inserted into the sample bottle, the bottle sealed and continually stirred, and the dissolved oxygen concetration continually recorded on a chart. The respiration rate was derived from the longest liner portion of the trace.
The reduction in respiration rate was determined as the difference between mean control and the test respiration rate expressed as a percentage of the mean control respiration rate. - Reference substance (positive control):
- yes
- Remarks:
- 3,5-Dichlorophenol
- Key result
- Duration:
- 3 h
- Dose descriptor:
- EC50
- Effect conc.:
- > 20 000 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- inhibition of total respiration
- Details on results:
- For the range-finder test no significant inhibition of respiration was observed with DCPMS at concentrations of 1.0 and 10 mg/l compared with the control solution. The percentage inhibitation relative to the controls seen at 100 mg/l and 1,000 mg/l was 15% and 29% respectively. Linear regression analysis (using log 10 concentration values) of these effects data gave the following estimated EC20 and EC50 (regression coefficient 0.9998).
EC20 = 233 mg/l
EC50 = 27,339 mg/l (note: extrapolated above the highest concentration tested).
For the definitive study, it was found the the mean respiration rate recorded for the controls was around 18% higher than recored in the corresponding samples in the range-finding study (see Tables below). The reason for this was not known but it was suggested in the test report that this may be related to adaptation of to the synthetic sewage substrate that was used to feed the inoculum during the interval between the range-finding and definintive study.
The percantagae inhibition compared with the control solution seen in the definitive test was between 17% and 24% at all concentrations tested and so it was not possible to determine an EC50 value.
The test report noted that there was a small descrepancy between the results of the range finding test (which found 29% inhibition at 1,000 mg/l and suggested and EC50 of around 27,000 mg/l) and the definitive test (which showed a maximum 24% inhibition at concentrations up to 20,000 mg/l). The report suggested that this discrepancy may result from inhibition of nitrification by DCPMS with no effect on carbonaeceous respiration. It was noted that carbonaceous respiration usually exceeds nitrogenous oxygen demand roughly in the proportion 70:30 and so the 29% inhibition seen in the range-finding test may suggest that nitrification was inhibited at 1,000 mg/l in this test. For the definitive test the highest inhibition was lower than in the range-finding test at 24%. The test report indicates that the reason for this was unknown but it was suggested that it was possible that the ratio of the carbonaceous respiration to nitrogenous oxygen demand may have shifted to approximately 75:25 by the time the sludge sample was used in the definitive test an again selective inhibition of nitrification would then explain the data seen. This is supported by the plateau observed in the definitive test where relatively little further inhibition occurred at concentrations above 1,000 mg/l. The test report indicates, however that further work with a method designed to assess chemicals for inhibition of nitrification would be required in order to resolve this matter conclusively.
It should be noted that the concentrations tested in the definitive study are all above the water solubility of the test substance. - Results with reference substance (positive control):
- For the range-finding test, the following effect concentrations were determined for 3,5-dichlorophenol.
EC20 = 2 mg/l
EC50 = 6 mg/l
EC80 = 15 mg/l
In the definitive test, the following effect concentrations were determined for 3,5-dichlorophenol
EC20 = 6 mg/l
EC50 = 15 mg/l
EC80 = 38 mg/l - Reported statistics and error estimates:
- The effect concentrations were estimated using linear regression analysis of the log 10 [concentration] against percentage inhibition of respiration rate.
The following regression coefficients were reported.
DCPMS - range-finding study = 0.9998.
DCPMS - definitive study = no regression analysis possible
3,5-dichlorophenol - range-finding study = 0.96077
3,5-dichlorophenol - definitive study = 0.99829 - Validity criteria fulfilled:
- yes
- Conclusions:
- The EC50 for DCPMS on respiration of activated sludge was found to be in excess of 20,000 mg/l.
- Endpoint:
- activated sludge respiration inhibition testing
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- other: Huls Method (oxygen consumption test)
- Principles of method if other than guideline:
- Determation of the toxicity to bacteria in an oxygen consumption test.
- GLP compliance:
- yes (incl. QA statement)
- Analytical monitoring:
- no
- Vehicle:
- yes
- Details on test solutions:
- Test solutions were made up using an emulsifier (nonylphenol ethoxylate (10 EO)/propoxylate (5 PO). The following concentrations of DCPMS were tested: 0.97, 9,7, 97 and 970 mg/l based on active substance.
Sterile control solutions were prepared using HgCl2 at a concentration of 3 mg/l.
The test medium was mineral salts medium containing glucose. - Test organisms (species):
- Pseudomonas putida
- Details on inoculum:
- The test species was Pseudomonas putida Migula. The inoculum concentration used was ca. 100,000 cells/ml.
- Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 5 h
- Remarks on exposure duration:
- The actual exposure duration was 4.92 hours.
- Test temperature:
- The tests were carried out at a temperature of 24.9 to 25.9 °C (mean 25.3 °C).
- Reference substance (positive control):
- no
- Duration:
- 5 h
- Dose descriptor:
- EC10
- Effect conc.:
- > 970 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: oxygen consumption
- Duration:
- 5 h
- Dose descriptor:
- EC50
- Effect conc.:
- > 970 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: oxygen consumption
- Details on results:
- No significant effect on oxygen consumption was seen in the test solutions with DCPMS when compared with controls at any concentration tested.
- Validity criteria fulfilled:
- yes
- Conclusions:
- The EC10 and EC50 for DCPMS was found to be in excess of 970 mg/l.
- Endpoint:
- activated sludge respiration inhibition testing
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
- GLP compliance:
- yes (incl. QA statement)
- Analytical monitoring:
- no
- Details on test solutions:
- The following five concentrations of DCPMS were tested: 20, 40.4, 60.4 78.4 and 100 mg/l.
The test solutions were prepared by adding 200 ml inoculum to 300 ml of the aqueous solutions containing the test substance and synthetic sewage (16 ml). The controls consisted of 200 ml inoculum added to 300 ml water containing 16 ml synthetic sewage. The reference substance solutions were similarly prepared with the appropriate amounts of 3,5-dichlorophenol. - Test organisms (species):
- activated sludge of a predominantly domestic sewage
- Details on inoculum:
- The activated sludge sample was collected from a municipal waste water treatment plant. The sludge was diluted in drinking water to give a suspended solids conentration of 2 g/l.
- Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 3 h
- Test temperature:
- The test temperature was in the range 20.5 to 22.0°C.
- pH:
- The pH of the solutions was in the range 8.1 to 8.4.
- Nominal and measured concentrations:
- The nominal concentrations of DCPMS were 20, 40.4, 60.4, 78.4 and 100 mg/l.
- Details on test conditions:
- The test solutions were incubated for 3 hours. The dissolved oxygen concentration was determined at the start and end of the incubation period and the respiration rate determined.
- Reference substance (positive control):
- yes
- Remarks:
- 3,5-dichlorophenol
- Key result
- Duration:
- 3 h
- Dose descriptor:
- EC10
- Effect conc.:
- > 100 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- inhibition of total respiration
- Details on results:
- The test substance was found to have little or no effect on the respiration rate compared with the controls at any concentration test. The highest reduction in respiration rate compared with the controls was 5.4% at a DCPMS concentration of 40.4 mg/l.
- Results with reference substance (positive control):
- The EC50 for the reference substance (3,5-dichlorophenol) was estimated to be 5.4 mg/l.
- Validity criteria fulfilled:
- yes
- Conclusions:
- The EC10 for DCPMS on respiration of activated sludge was found to be in excess of 100 mg/l.
Referenceopen allclose all
Table 2: Controls, reference substance (3, 5-dichlorophenol) and test substance: oxygen consumption and percentage inhibition of the respiration rate.
|
Flask |
Nominal concentration (mg/l) |
Oxygen consumption (mg O2/l/min) |
% Inhibition respiration rate |
1 |
Inoculum control |
0 |
0.935 |
- |
12 |
Inoculum control |
0 |
1.004 |
- |
|
Mean |
0.970 |
|
|
|
|
|||
7 |
Test substance |
100 |
0.976 |
-0.7 |
8 |
Test substance |
50 |
1.061 |
-9.4 |
9 |
Test substance |
24 |
0.979 |
-1.0 |
10 |
Test substance |
12 |
1.029 |
-6.1 |
11 |
Test substance |
6 |
1.066 |
-10.0 |
|
|
|||
2 |
Reference substance |
100 |
0.094 |
90.3 |
3 |
Reference substance |
32 |
0.198 |
79.6 |
4 |
Reference substance |
10 |
0.778 |
19.8 |
5 |
Reference substance |
3.2 |
0.975 |
-0.6 |
The results from the range-finding study are summarised in Table 1.
Table 1: Respiration rate and inhibition data from the range-finding study
Treatment | Replicate | Respiration rate (mg O2/l . h) | Percentage inhibition | |||
Individual values | Mean | |||||
Control | 1 (start of series) | 50.20 | 49.31 | - | ||
2 (start of series) | 49.50 | |||||
3 (end of series) | 49.61 | |||||
4 (end of series) | 47.91 | |||||
1.0 mg/l DCMPS | 1 | 49.40 | 48.23 | 2% | ||
2 | 47.06 | |||||
10 mg/l DCMPS | 1 | 49.70 | 49.23 | 0% | ||
2 | 48.75 | |||||
100 mg/l DCMPS | 1 | 42.13 | 41.91 | 15% | ||
2 | 41.68 | |||||
1,000 mg/l DCMPS | 1 | 35.71 | 34.89 | 29% | ||
2 | 34.06 | |||||
5 mg/l 3,5-dichlorophenol | 1 | 29.15 | 41% | |||
15 mg/l 3,5-dichlorophenol | 1 | 11.13 | 77% | |||
45 mg/l 3,5 -dichlorophenol | 1 | 5.39 | 89% |
The results from the definitive study are summarised in Table 2.
Table 2: Respiration rate and inhibition data from the definitive study
Treatment | Replicate | Respiration rate (mg O2/l . h) | Percentage inhibition | |||
Individual values | Mean | |||||
Control | 1 (start of series) | 54.95 | 58.40 | - | ||
2 (start of series) | 57.46 | |||||
3 (end of series) | 68.451 | |||||
4 (end of series) | 62.79 | |||||
1,000 mg/l DCMPS | 1 | 49.40 | 48.23 | 2% | ||
2 | 47.06 | |||||
10 mg/l DCMPS | 1 | 49.70 | 49.23 | 0% | ||
2 | 48.75 | |||||
100 mg/l DCMPS | 1 | 42.13 | 41.91 | 15% | ||
2 | 41.68 | |||||
1,000 mg/l DCMPS | 1 | 35.71 | 34.89 | 29% | ||
2 | 34.06 | |||||
5 mg/l 3,5-dichlorophenol | 1 | 29.15 | 41% | |||
15 mg/l 3,5-dichlorophenol | 1 | 11.13 | 77% | |||
45 mg/l 3,5 -dichlorophenol | 1 | 5.39 | 89% |
The results are summarised in Table 1.
Table 1: Oxygen consumption and inhibition test
Treatment | Mean dissloved oxygen concentration (mg O2/l) | Oxygen consumption (mg O2/l) | Percentage inhibition | |
Start of test | End of test | |||
Controls (four replicates) | 8.71 | 4.05 | 4.66 | |
0.97 mg/l DCPMS (2 replicates) | 8.83 | 4.13 | 4.70 | -0.9% |
9.7 mg/l DCPMS (2 replicates) | 8.83 | 4.19 | 4.65 | 0.3% |
97 mg/l DCPMS (2 replicates) | 8.67 | 4.23 | 4.44 | 4.8% |
970 mg/l DCPMS (2 replicates) | 8.84 | 4.07 | 4.77 | -2.3% |
The results from the study are summarised in Table 1.
Table 1: Respiration rate and inhibition data
Treatment | Respiration rate (mg O2/l . h) | Percentage inhibition |
5 mg/l 3,5-dichlorophenol | 9.35 | 47.4% |
7 mg/l 3,5-dichlorophenol | 7.30 | 58.9% |
10 mg/l 3,5-dichlorophenol | 4.89 | 72.5% |
100 mg/l DCPMS | 16.95 | 4.6% |
78.4 mg/l DCPMS | 18.00 | -1.3% |
60.4 mg/l DCPMS | 17.70 | 0.4% |
40.4 mg/l DCPMS | 16.80 | 5.4% |
20 mg/l DCPMS | 17.04 | 4.1% |
Control - replicate 1 | 17.27 | |
Control - replicate 2 | 18.26 |
Description of key information
Toxicity to microorganisms:
Parent substance: Activated sludge respiration inhibition EC50 >1000 mg/L based on weight of evidence from three respiration inhibition tests for the structurally-related substance dicyclopentyldimethoxysilane.
Hydrolysis product: Activated sludge respiration inhibition EC50 >100 mg/L (nominal), based on read-across from the structurally-related substance dicyclopentyldichlorosilane.
Key value for chemical safety assessment
Additional information
There are no microorganism toxicity data available for cyclohexyl(dimethoxy)methylsilane, therefore good quality data for the structurally-related substance dicyclopentyl(dimethoxy)silane (CAS 126990-35-0), have been read across. The hydrolysis of the submission substance has been read-across from dicyclopentyl(dimethoxy)silane. The target and source substances both hydrolyse moderately rapidly to structurally-related hydrolysis products, cyclohexylmethylsilanediol and dicyclopentylsilanediol respectively. The other hydrolysis product is methanol for both substances. In view of the hydrolysis half-life (19 hours at pH 7 and 25°C), the assessment of the STP is based on that of the parent substance.
Methanol does not have adverse effects on microorganisms (OECD 2004).
Cyclohexyl(dimethoxy)methylsilane (CAS 17865-32-6) and dicyclopentyl(dimethoxy)silane (CAS 126990-35-0) are within a group of substances within which in general, there is no evidence of significant toxicity to microorganisms. This group consists of substances containing a number of different functional groups but specific read-across is between substances with similar functionality.
Table 7.4.2 presents microorganism toxicity data available for substances relevant to cyclohexyl(dimethoxy)methylsilane.
It is considered valid to read-across the results for dicyclopentyl(dimethoxy)silane (CAS 126990-35-0) to fill the data gap for the registered substance since the source and target substances generate structurally analogous silanol hydrolysis products.
Additional information is given in a supporting report (PFA, 2013j) attached in Section 13.
Table: Microorganism toxicity data for relevant substances
CAS |
Name |
Result: E(I)C50 (mg/L) |
Result: NOEC (or EC10/ EC20) (mg/L) |
Guideline |
Test method |
Species |
Duration |
Klimisch code |
1066-40-6 |
Hydroxytrimethylsilane |
6670 |
|
OECD 209 and ISO 1892 |
ASRI |
|
uncertain |
2 |
31795-24-1 |
Potassium methylsilanetriolate |
|
EC10 >100 |
OECD 209 |
ASRI |
|
3 h |
1 |
139147-73-2 |
Silane, dichlorodicyclopentyl- |
>100 |
|
OECD 209 |
ASRI |
|
3 h |
1 |
124-70-9 |
Dichloro(methyl)(vinyl)silane |
>100 |
EC10 >100 |
OECD 209 |
ASRI |
|
3 h |
1 |
126990-35-0 |
Dicyclopentyldimethoxysilane |
>water solubility; >water solubility; >water solubility (WOE) |
|
OECD 209/EU C11/Huls AG method (WOE) |
ASRI/ASRI/oxygen consumption P. putida (WOE) |
|
3 h; 3h; 3h (WOE) |
1/1/2 (WOE)
|
1000-50-6 |
Butylchlorodimethylsilane |
>340 |
|
88/302/EC |
ASRI |
|
3h |
1 |
13154-25-1 |
Chlorotri(3-methyl-propyl)silane |
>1000 (nominal, parent) |
100 (nominal, parent) |
OECD 209 |
ASRI |
|
3 h |
2 |
5894-60-0 |
Trichloro(hexadecyl)silane |
>1000 |
≥1000 Nitrification control indicated no heterotrophic inhibition of respiration rate |
OECD 209 |
ASRI |
|
3h |
1 |
75-94-5 |
Trichloro(vinyl)silane |
|
>100 |
OECD 209 |
ASRI |
|
3h |
1 |
1185-55-3 |
Trimethoxy(methyl)silane |
>100 |
EC10 >100 |
OECD 209 |
ASRI |
|
3h |
1 |
17980-47-1 |
Triethoxyisobutylsilane |
>1000 |
≥1000 |
OECD 209 |
ASRI |
|
3h |
1 |
2943-75-1 |
Triethoxyoctylsilane |
>1000 |
≥1000 Nitrification control indicated no heterotrophic inhibition of respiration rate |
OECD 209 |
ASRI |
|
3 h |
1 |
16068-37-4 |
4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disiladecane |
>8000 |
8000 |
DIN 38 412, Part 8 (Pseudomonas cell multiplication inhibition test) |
growth inhibition test |
P. putida |
16 h |
1 |
35435-21-3 |
Triethoxy(2,4,4-trimethylpentyl)silane |
>100 |
|
OECD 209 |
ASRI |
|
3h |
1 |
87135-01-1 |
1,6-Bis(trimethoxysilyl)hexane |
>1000 |
|
OECD 209 |
ASRI |
|
3h |
1 |
87135-01-1 |
1,6-Bis(trimethoxysilyl)hexane |
>1000 |
|
OECD 209 |
ASRI |
|
3h |
1 |
16415-12-6 |
Hexadecyltrimethoxysilane |
>1000 |
Nitrification control indicated no heterotrophic inhibition of respiration rate. |
OECD 209 |
ASRI |
|
3 h |
1 |
18395-30-7 |
Trimethoxy(2-methylpropyl)silane |
|
EC10 1.3 ml/L |
Huls AG method |
oxygen consumption |
P. putida |
5.8 h |
2 |
2768-02-7 |
Trimethoxyvinylsilane |
|
EC10 1.1 ml/L |
Huls AG method |
oxygen consumption |
P. putida |
5 h |
2 |
142877-45-0 |
Silane, trimethoxy(1,1,2-trimethylpropyl)- |
>1000 |
≥1000 |
OECD 209 |
ASRI |
|
3 h |
1 |
The effect of dicyclopentyl(dimethoxy)silane on the respiration rate of activated sludge has been investigated in two studies using standard guidelines and conducted according to GLP. In both studies no effects were seen at the highest concentration tested (20000 mg/L and 100 mg/L). The effect on the respiration rate of Pseudomonas putida has also been investigated, in a study conducted according to GLP. No effects were seen at the highest concentration tested (970 mg/L).
These studies were conducted at concentrations far higher than the water solubility of the parent substance. Where the experimentally derived EC50 is higher than the aqueous solubility, it can still be used as valid information to derive a PNECstp as untreated wastewater may well contain undissolved material above the limit of solubility. However, 20000 mg/L is considered to represent an unrealistic release rate, and therefore the value is capped at 1000 mg/L.
It is expected that cyclohexyl(dimethoxy)methylsilane would show a similarly low level of toxicity to microbial processes. This conclusion is supported by the information from a toxicity control from a ready biodegradation test (outlined in IUCLID Section 5.2.1, CSR Section 4.1.2.1) which showed that cyclohexyl(dimethoxy)methylsilane at concentrations up to 10 mg/L was not inhibitory to the degradation of sodium benzoate.
No data are available for the hydrolysis product of the submission substance, cyclohexylmethylsilanediol. An EC50 of >100 mg/L (nominal) has been determined for the structurally-related substance dicyclopentyldichlorosilane (CAS 139147-73-2), which has a similar hydrolysis product to cyclohexyl(dimethoxy)methylsilane.
Dicyclopentyldichlorosilane hydrolyses very rapidly, and the activated sludge would have been exposed to the hydrolysis product, dicyclopentylsilanediol. The other hydrolysis product of dicyclopentyldichlorosilane is HCl. Effects of hydrochloric acid on microorganisms are limited to those that result from changes to pH in unbuffered media.
Reference:
PFA (2013j). Peter Fisk Associates, STP Microorganism toxicity Main Analogue Group report, PFA.300.003.006
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