4,4,13,13-tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1998-09-24 to 1998-09-26

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Guideline study with acceptable restrictions. The study was conducted according to an appropriate OECD test guideline. It was not compliant with GLP. The restriction was that there was no analysis of exposure concentrations and it is likely that the solubility of the test substance was exceeded in the test.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

no

Analytical monitoring:

no

Details on sampling:

not applicable

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: 10 mg and 1 mg of the test substance were weighed onto a small polyethylene platelett. The plateletts were then transferred to 1 litre polyethylene bottles. The bottles were each filled with 1 litre of oxygen-saturated dilution water and sealed with a screw cap. They were then shaken for 20 hours at 20+/-1.5ºC before being allowed to settle for 4 hours. The resulting solutions were then transferred into four replicate 100 ml polyethylene test vessels. The vessels were sealed during the exposure period.

- Controls: Dilution water

- Evidence of undissolved material (e.g. precipitate, surface film, etc): the solubility of the test substance is noted as being in the order of 1 mg/l and therefore it is possible that undissolved test material was present at the highest loading rate.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Source: Dr. Knie, LWA

- Age at study initiation (mean and range, SD): <24 hours

- Method of breeding: laboratory stock culture

- Feeding during test: none

ACCLIMATION

- Acclimation conditions: same as test

- Type and amount of food: green algae Scenedesmus subspicatus

- Feeding frequency: daily

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

no data

Test temperature:

21.0-21.4ºC

pH:

7.20-7.43

Dissolved oxygen:

7.5-8.0 mg/l

Salinity:

not applicable

Nominal and measured concentrations:

Nominal loading rates: 1 and 10 mg/l

Details on test conditions:

TEST SYSTEM

- Test vessel: flasks

- Type: closed

- Material, size, headspace, fill volume: polyethylene, 100 ml, no headspace, 100 ml

- Aeration: none
- Other: The test vessels were placed on a light table to discourage the test organisms from coming into contact with undissolved test substance on the surface of the test medium.

- Renewal rate of test solution (frequency/flow rate): 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 dahnid/20 ml test medium

TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: drinking water

- Culture medium different from test medium: no

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

OTHER TEST CONDITIONS

- Adjustment of pH: no

- Photoperiod: 16 h light, 8 h dark

EFFECT PARAMETERS MEASURED: mobility after 24 and 48 hours

TEST CONCENTRATIONS

- Spacing factor for test loading rates: 10

- Justification for using less concentrations than requested by guideline: no data

- Range finding study: no data

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

< 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

< 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

< 1 mg/L

Nominal / measured:

nominal

Conc. based on:

other: expected water solubility of the test substance

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

< 1 mg/L

Nominal / measured:

nominal

Conc. based on:

other: expected water solubility of the test substance

Basis for effect:

mobility

Details on results:

- Other biological observations: Microscopic examination of the test organisms exposed to both treatments showed evidence of physical fouling of the antennae with the test substance. The report authors attribute the observed immobility of the test organisms to this phenomenon.

- Mortality of control: 0

- Effect concentrations exceeding solubility of substance in test medium: The report authors note the presence of undissolved test material causing fouling of the test organisms.

Results with reference substance (positive control):

no data

Reported statistics and error estimates:

No statistical test were applied to the results

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)	0	0
1	75	75
10	95	100

Validity criteria fulfilled:

yes

Conclusions:

A 48-h EL50 value of <1 mg/l and NOELR of <1 mg/l) have been determined for the effects of the test substance on mobility of Daphnia magna. It is likely that the observed effects on the test organisms resulted, at least in part, from exposure to undissolved test material even though steps were taken to avoid this in the test procedure.

Description of key information

EL₅₀ (48 h): <1 mg/l (nominal) based on: mobility of Daphnia magna (nominal) (OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test). Evidence of physical fouling was seen in the test at both loading levels and therefore effects seen are attributed to physical effects caused by undissolved test substance or precipitated by-products. Therefore, this value is not used as the basis of PNECaquatic values.

Additional information

A 48-hour EL₅₀ value of <1 mg/l has been determined for effects of 4,4,13,13-tetraethoxy-3,14 -dioxa-8,9-diatha-4,13-disilahexadecane (S2) (CAS 56706-10-6, EC 260-350-7) on the mobility of Daphnia magna in a test conducted according to OECD TG 202 (Evonik Degussa, 1998b). In this study, the water solubility of the substance (0.014 mg/l at 20°C) was exceeded at the tested loading rates and undissolved test substance was observed to be present in the test media. It is likely that, because of the test medium preparation method and exposure regime, the test organisms were exposed to a mixture of the parent substance, the hydrolysis products and undissolved test substance and/or precipitated oligomeric by-products. It is likely that the observed effects on the test organisms resulted, at least in part, from exposure to undissolved test material or precipitate, even though steps were taken to avoid this in the test procedure. The results of this test were selected as key in preference to those of a second test of equal reliability, because they gave a more conservative 48 h EL₅₀.

A 48-hour EL₅₀ value of >10 mg/l has been determined for the effects of the read-across substance, bis[3-(triethoxysilyl)propyl]polysulfides (CAS 211519-85-6, EC 915-673-4), on the mobility of Daphnia magna. The water solubility of the substance (0.01-0.014 mg/l, estimated) was exceeded at the tested loading rates and undissolved test substance was observed to be present in the test media. It is likely that, because of the prolonged test medium preparation phase, the test organisms were exposed to a mixture of the parent constituents and a mixture of the monomeric silanol hydrolysis product and its siloxane oligomers. Insoluble oligomers may have precipitated out of solution to an extent during the media preparation and during the test. The test results have been interpreted in this context. This is reflected in the observation of turbidity in test media, although no analytical verification was performed. The test substance is a multiconstituent reaction mass of 4,4,15,15-tetraethoxy-3,16-dioxa-8,9,10,11-tetrathia-4,15-disilaoctadecane and 4,4,14,14-tetraethoxy-3,15-dioxa-8,9,10-trithia-4,14-disilaheptadecane and 4,4,13,13-tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane. One constituent is the registered substance (CAS 56706-10-6).