Trimethoxy(2,4,4-trimethylpentyl)silane

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Data waiving:

other justification

Justification for data waiving:

the study does not need to be conducted because a long-term aquatic toxicity study on invertebrates is available

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

2002-05-09 to 2002-08-17

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The test report summary clearly states “..the undiluted filtrate with the maximum concentration of dissolved respectively very fine dispersed test substance was used as stock solution for lower concentrated test media.” Nominal and measured test concentrations were inconsistent.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

The test media were not prepared in accordance with OECD guidance for testing difficult substances.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Nominal treatments: 0 (Control), 2.15, 4.64, 10.0, 21.5, 46.4 and 100 mg/L

- Sampling method: One aliquot from the freshly prepared test media of all test concentrations was taken at the start of the test before filling the test vessels. A combined aliquot was collected from the test media of all 4 replicate test vessels at each concentration at the end of the test.

- Sample storage conditions before analysis: Samples were stored at -20ºC prior to analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: A stock suspension of the test substance was prepared at a nominal loading rate of 100 mg/L by shaking for approximately 48 hours. The suspension was then filtered through a 0.45 μm cellulose acetate filter. Further treatments were prepared by dilution of the resulting stock solution.

- Controls: Dilution water

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Source: IRChA, France

- Age at study initiation: 6-24 hours

- Method of breeding: Laboratory stock culture

- Feeding during test: none

ACCLIMATION

- Acclimation period: at least 1 week

- Acclimation conditions: same as test

- Type and amount of food: log-phase Scenedesmus subspicatus and a small amount of aerated sewage sludge

- Feeding frequency: not reported

- Health during acclimation (any mortality observed): not reported

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg/l as CaCO3

Test temperature:

20+/-1ºC

pH:

7.61-8.16

Dissolved oxygen:

≥80% ASV

Salinity:

not applicable

Nominal and measured concentrations:

- Nominal treatments: 0 (Control), 2.15, 4.64, 10.0, 21.5, 46.4 and 100 mg/L

- The measured concentrations at the start and end of the test were <20% of the theoretical values. The discrepancy is attributed by the report author to the low solubility of the substance.

The test results are expressed in the test report relative to nominal concentrations (loading rates). The results have been reinterpreted by the reviewer with reference to the measured DOC concentrations and corresponding test substance concentrations.

Details on test conditions:

TEST SYSTEM

- Test vessel:

- Type: open

- Material, size, fill volume: glass, 50 mL with 50 mL of test medium

- Aeration: none

- Renewal rate of test solution: static test

- No. of organisms per vessel: 5

- No. of vessels per concentration (replicates): 4

- No. of vessels per control (replicates): 4

- Biomass loading rate: 1 daphnid/10 mL

TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: reconstituted fresh water

- Alkalinity: 0.8 mmol/L

- Ca/mg ratio: 4:1

- Intervals of water quality measurement: start and end of test

OTHER TEST CONDITIONS

- Adjustment of pH: no

- Photoperiod: 16 hours light, 8 hours dark

- Light intensity: approximately 500 lux

EFFECT PARAMETERS MEASURED: mobility after 24 and 48 hours

TEST CONCENTRATIONS

- Spacing factor for test concentrations: 2.2

- Range finding study

- Results used to determine the conditions for the definitive study: no data

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

2.15 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

13 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 2.0-36

Details on results:

- Immobilisation of control: 5%

- Any observations that might cause a difference between measured and nominal values: It is speculated in the test report that the lack of agreement between nominal and measured exposure concentrations may be a consequence of the low solubility of the test substance.

Reported statistics and error estimates:

EC50 (EL50) values based on nominal concentrations were calculated by linear regression employing probit analysis (Probit Program Version 1.5, U.S. Environmental Protection Agency, 1992). The NOELR values were taken directly from the raw data.

Table 1. Test results

Nominal test substance loading rate (mg/L)	Mean percentage immobilisation after 24 hours	Mean percentage immobilisation after 48 hours
0 (Control)	2.5	5
2.15	0	5
4.64	10	40
10.0	5	20
21.5	30	70
46.4	70	95
100	70	95

Table 2. Results of analysis of test media

Nominal test substance loading rate (mg/L)	Theoretical DOC concentration (mg/L)	Actual DOC concentration at start of test (mg/L)	Actual DOC concentration at end of test (mg/L)
2.15	1.2	1.2	1.6
4.64	2.5	1.3	1.3
10.0	5.4	1.6	1.6
21.5	11.6	1.6	2.0
46.4	25.1	3.8	4.9
100	54.0	8.0	8.1

Validity criteria fulfilled:

no

Conclusions:

A 48-h EL50 value of 13 mg/l and a NOELR of 2.15 mg/l have been determined for the effects of the test substance on mobility of Daphnia magna based on nominal test substance loading rates. The study was severely compromised by significant methodological deficiencies or use of unsuitable test system; results not fit for purpose.

Additional information

In accordance with Column 2 of REACH Annex VII, the short-term aquatic toxicity study with invertebrates does not need to be conducted as a reliable long-term aquatic toxicity study with invertebrates is available.