Allyltrimethylsilane

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 Jun - 12 Jul 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

2006

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom

Test material

Test material information

Constituent 1

Reference substance name:

Allyltrimethylsilane

EC Number:

212-104-5

EC Name:

Allyltrimethylsilane

Cas Number:

762-72-1

Molecular formula:

C6H14Si

IUPAC Name:

allyltrimethylsilane

Test material form:

liquid

Sampling and analysis

Analytical monitoring:

yes

Remarks:

GC

Details on sampling:

- Concentrations: 2.6, 6.4, 16, 40 and 100% v/v saturated solution
- Sampling method: Samples were taken from the control and each test group from the bulk test preparation at 0 hours and from the pooled replicates at 72 hours for quantitative analysis. All samples were analyzed on the day of sampling. Additional samples of each test concentration were incubated alongside the test to provide samples for analysis at 24 and 48 hours.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Preliminary solubility work conducted indicated that it was not possible to obtain a testable solution of the test item using traditional methods of preparation e.g. ultrasonication and high shear mixing. A preliminary media preparation trial indicated that a dissolved test item concentration of approximately 4.3 mg/L was obtained from a saturated solution method of preparation indicating this to be the limit of water solubility of this item under test conditions. For more details see field "any other information on material and methods incl. tables".
- Method: Six nominal amounts of test item (27.8 mg) were each dispersed under the surface of 555 mL of culture media in completely filled glass conical flasks sealed with ground glass stoppers to give initial test item dispersions of 50 mg/L. These were shaken in an incubator at approximately 150 rpm at a temperature of 21°C for 24 hours. Then any undissolved test item was removed by filtration of the pooled replicate flasks, through a 0.2 µm Gelman Acrocap filter (first approximate 100 mL used to pre-condition the filter was discarded) to produce a 100% v/v saturated solution of the test item. A series of dilutions was made from this saturated solution to give further stock solutions of 2.6, 6.4, 16 and 40% v/v saturated solution. An aliquot (1800 mL) of each of the stock solutions was separately inoculated with 6.3 mL of algal suspension to give the required test concentrations of 2.6, 6.4, 16, 40 and 100% v/v saturated solution.
- Differential loading: No
- Controls: Culture medium only

Test organisms

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: CCAP 278/4
- Source: Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd, Scottish Marine Institute, Oban, Scotland
- Age of inoculum (at test initiation): 3 to 4 days before the start of the test, inoculum cultures of algae was set up.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

24 ± 1 ºC

pH:

7.8 - 10.6

Nominal and measured concentrations:

Nominal concentrations: 0 (control), 2.6, 6.4, 16, 40 and 100% v/v saturated solution
Geometric mean measured concentrations: < LOQ (control), 0.069, 0.12, 0.27, 0.63 and 1.0 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL glass stoppered conical flasks
- Type: closed with ground glass stoppers
- Fill volume: 250 mL
- Aeration: no
- Initial cells density: 5 x 10^3 cells/mL
- Control end cells density: 7.10 x 10^5
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: AAP medium (according to the guideline) and an additional 250 mg/L of NaHCO3 was added to the culture medium prior to use.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reverse osmosis purified deionized water
- Culture medium different from test medium: no
- Intervals of water quality measurement: The pH of the control and each test preparation was determined at initiation of the test and after 72 hours exposure. The pH was measured using a Hach HQ30d Flexi handheld meter. The temperature within the incubator was recorded daily.

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: warm white light (380 - 730 nm), approx. 7000 lux

EFFECT PARAMETERS MEASURED: At 25, 46 and 72 hours: cell densities, at 72 hours: shape and size of the algal cells was inspected microscopically and any abnormalities were recorded.
- Determination of cell concentrations: Coulter® Multisizer Particle Counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.5
- Range finding study: yes
- Test concentrations: 0.10, 1.0, 10 and 100% v/v saturated solution
- Results used to determine the conditions for the definitive study: no effect on growth at the test concentrations of 0.10, 1.0 and 10% v/v saturated solution. Growth was observed to be reduced at 100% v/v saturated solution.

Reference substance (positive control):

yes

Remarks:

performed twice in a 12 month period with potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

No abnormalities were detected in the control or test cultures at 0.069 and 0.12 mg/L. Some cell clumping was observed to be present in the test cultures at 0.27 and 0.63 mg/L whilst some misshapen cells were observed to be present in the test culture at 1.0 mg/L.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50 (growth rate): 1.5 mg/L; 95% confidence limits 1.3 to 1.7 mg/L
- Other: NOEC (growth rate): 0.50 mg/L, LOEC (growth rate): 1.0 mg/L

Reported statistics and error estimates:

Statistical analysis of the growth rate data was carried out for the control and all test concentrations using one way analysis of variance incorporating Bartlett's test for homogeneity of variance (Sokal and Rohlf, 1981) and Dunnett's multiple comparison procedure for comparing several treatments with a control (Dunnett, 1955).

Any other information on results incl. tables

Table 1: Further effect values

ResponseVariable	EC50 (mg/L)	95% Confidence Limits (mg/L)	No Observed Effect Concentration (NOEC) (mg/L)	Lowest Observed Effect Concentration (LOEC) (mg/L)
Growth Rate	> 1.0	Not determined	0.63	1.0
Yield	> 1.0	Not determined	0.63	1.0

Table 2: Analytical results.

Nominal concentration of the test item in samples (% v/v saturated solution)	Determined concentration of the test item (mg/L)				Geometric mean (mg/L)
	0 hours	24 hours	48 hours	72 hours
Control	< LOQ	Not measured	Not measured	Not detected
2.6	0.133	< LOQ	< LOQ	Not detected	0.069
6.4	0.265	0.167	< LOQ	< LOQ	0.12
16	0.619	0.307	0.220	< LOQ	0.27
40	1.57	0.765	0.509	< LOQ	0.63
100	4.02	0.858	0.637	0.277	1.0

Table 3: Cell densities after 25, 46 and 72 hours after test initiation.

Geometric mean measured concentration (mg/L)		Cell densities* (cells per mL)
		25 hour	46 Hour	72 Hour
Control	R1	3.50E+04	1.94E+05	7.32E+05
	R2	3.31E+04	1.83E+05	7.05E+05
	R3	3.70E+04	2.16E+05	6.84E+05
	R4	3.55E+04	2.00E+05	7.02E+05
	R5	3.36E+04	1.73E+05	6.90E+05
	R6	3.21E+04	1.83E+05	7.44E+05
	Mean	3.44E+04	1.92E+05	7.10E+05
0.069	R1	3.42E+04	1.85E+05	6.53E+05
	R2	3.66E+04	1.96E+05	7.53E+05
	R3	3.17E+04	2.51E+05	7.27E+05
	Mean	3.42E+04	2.11E+05	7.11E+05
0.12	R1	3.36E+04	1.96E+05	7.41E+05
	R2	3.41E+04	2.12E+05	7.69E+05
	R3	3.89E+04	1.96E+05	7.40E+05
	Mean	3.55E+04	2.01E+05	7.50E+05
0.27	R1	2.87E+04	1.61E+05	7.16E+05
	R2	2.84E+04	1.86E+05	7.15E+05
	R3	2.89E+04	1.57E+05	6.74E+05
	Mean	2.87E+04	1.68E+05	7.02E+05
0.63	R1	2.38E+04	1.41E+05	6.67E+05
	R2	2.60E+04	1.41E+05	6.72E+05
	R3	2.23E+04	1.37E+05	6.09E+05
	Mean	2.40E+04	1.40E+05	6.49E+05
1.0	R1	1.82E+04	8.86E+04	5.17E+05
	R2	1.56E+04	6.57E+04	4.03E+05
	R3	2.09E+04	1.04E+05	5.42E+05
	Mean	1.82E+04	8.61E+04	4.87E+05

*  Cell densities represent the mean number of cells per mL calculated from the mean of the cell counts from 3 counts for each of the replicateflasks.

R = Replicate

Table 4: Daily specific growth rates for the control cultures  

Treatment		Daily Specific Growth Rate (cells/mL/hour)
		Day 0 to 1	Day 1 to 2	Day 2 to 3
Control	R1	0.078	0.082	0.051
	R2	0.076	0.081	0.052
	R3	0.080	0.084	0.044
	R4	0.078	0.082	0.048
	R5	0.076	0.078	0.053
	R6	0.074	0.083	0.054
	Mean	0.077	0.082	0.050

Table 5: Inhibition of growth rate and yield.

Geometric mean measured concentration (mg/L)		Growth rate (cells/mL/hour)		Yield (cells/mL)
		0 to 72 Hour	% Inhibition	0 to 72 Hour	% Inhibition*
Control	R1	0.069	-	7.27E+05	-
	R2	0.069		7.00E+05
	R3	0.068		6.79E+05
	R4	0.069		6.97E+05
	R5	0.068		6.85E+05
	R6	0.069		7.39E+05
	Mean	0.069		7.05E+05
	SD	0.001		2.38E+04
0.069	R1	0.068	1	6.48E+05
	R2	0.070	[1]	7.48E+05
	R3	0.069	0	7.22E+05
	Mean	0.069	0	7.06E+05	0
	SD	0.001		5.17E+04
0.12	R1	0.069	0	7.36E+05
	R2	0.070	[1]	7.64E+05
	R3	0.069	0	7.35E+05
	Mean	0.069	[0]	7.45E+05	[6]
	SD	0.001		1.66E+04
0.27	R1	0.069	0	7.11E+05
	R2	0.069	0	7.10E+05
	R3	0.068	1	6.69E+05
	Mean	0.069	0	6.97E+05	1
	SD	0.001		2.37E+04
0.63	R1	0.068	1	6.62E+05
	R2	0.068	1	6.67E+05
	R3	0.067	3	6.04E+05
	Mean	0.068	2	6.44E+05	9
	SD	0.001		3.48E+04
1.0	R1	0.064	7	5.12E+05
	R2	0.061	12	3.98E+05
	R3	0.065	6	5.37E+05
	Mean	0.063	8	4.82E+05	32
	SD	0.002		7.39E+04

*          In accordance with the OECD test guideline only the mean value for yield for each test concentration is calculated

R  = Replicate

-    = Notapplicable

SD = Standard deviation

[ ] = Increase in growth compared to controls

Table 6: Validity criteria for OECD 201.

Criterion from the guideline	Outcome	Validity criterion fulfilled
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.	142	yes
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%	25%	yes
The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.	1%	yes

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.