Diethoxy(methyl)silane

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994-05-10 to 1994-05-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 500 mg/l nominal treatment
- Sampling method: Samples of test media were taken at the start and end of the test.
- Sample storage conditions before analysis: Refrigerated

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A 500 mg/l nominal concentration of the test substance was prepared by stirring overnight.
- Controls: Dilution water (algal growth medium)

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa (CCAP), Institute of Freshwater Ecology, Ambleside, Cumbria, U.K.
- Age of inoculum (at test initiation): Cultures in exponential growth
- Method of cultivation: Axenic cultures maitained in liquid medium.


ACCLIMATION
- Culturing media and conditions: same as test

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

no data

Test temperature:

24ºC

pH:

Control: 7.9 - 9.6

500 mg/l treatment: 7.9 - 9.3

Dissolved oxygen:

no data

Salinity:

not applicable

Nominal and measured concentrations:

Nominal concentration: 500 mg/l
Measured concentration at start of test: 486 mg/l
Measured concentration at end of test: 508 mg/l
Mean measured concentration: 497 mg/l
Mean measured concentration as a % of nominal: 99.4
The test results are presented and interpreted with reference to nominal concentrations.

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Type: closed
- Material, size, headspace, fill volume: Glass, 250 ml, no headspace, full
- Aeration: no
- Renewal rate of test solution (frequency/flow rate): no
- Initial cells density: 10000 cells/ml
- Control end cells density: ≈250000 cells/ml
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 4

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Standard algal growth medium in accordance with EU test method.
- Culture medium different from test medium: no


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: Continuous
- Light intensity and quality: 12527 - 11745 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 500 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 500 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 500 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 500 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes
- Any stimulation of growth found in any treatment: no

Reported statistics and error estimates:

No toxic effects were observed in the test media, the test results were therefore not subject to statistical analysis.

Validity criteria fulfilled:

yes

Conclusions:

A 72-h EC50 value of > 500 mg/l and NOEC of ≥ 500 mg/l have been determined for the effects of the test substance on growth rate of Pseudokirchnerella subcapitata (tested as: Selenastrum capricornutum) based on nominal concentration of the substance. However it is likely that the test organisms were primarily exposed to the hydrolysis products of the substance.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to the attached justification below and the overall justification for grouping of substances attached in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 500 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 500 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Description of key information

ErC50 (72 h) > 500 mg/L and NOErC (72 h) ≥ 500 mg/L (nominal, EU Method C.3); based on read across from CAS 2031 -67 -6

Key value for chemical safety assessment

EC50 for freshwater algae:

500 mg/L

EC10 or NOEC for freshwater algae:

500 mg/L

Additional information

There are no reliable data available on the toxicity of diethoxy(methyl)silane (CAS 2031-62-1) to aquatic algae. In accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5 “Grouping of substances and read-across” and in accordance with the read across assessment framework (RAAF, ECHA 2017) a read-across from the analogous substance triethoxy(methyl)silane (CAS 2031-67-6) has been applied to support the environmental hazard assessment of diethoxy(methyl)silane. Details on the read across justification can be found in the attached justification in the respective target entry and in the overall justification for grouping of substances attached in IUCLID Section 13.

A 72-h ErC50 value of > 500 mg/L and a NOErC of ≥ 500 mg/L have been determined for the effects of triethoxy(methyl)silane (CAS 2031-67-6) on the growth rate of Pseudokirchneriella subcapitata based on nominal concentration of the substance. The study was conducted according to a standard guideline (EU Method C.3) and GLP (1994). Since the substance hydrolyses rapidly (< 2 min at pH 7 and 25 °C), it is very likely that the test organisms were predominantly exposed to the hydrolysis product retained in the test media.

On the basis of the read across data, no toxicity of diethoxy(methyl)silane (CAS 2031-62-1) to aquatic algae is expected.