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Ecotoxicological information

Short-term toxicity to fish

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short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1998-10-18 to 1998-10-23
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to guideline
OECD Guideline 203 (Fish, Acute Toxicity Test)
GLP compliance:
yes (incl. QA statement)
Analysis of test medium was not conducted in a GLP laboratory
Analytical monitoring:
Details on sampling:
- Concentrations: Control and 1000 mg/L

- Sampling method: A sample of freshly prepared and 24 hour-old test medium was taken for analysis.

- Sample storage conditions before analysis: no data
Details on test solutions:

- Method: Suspensions of the test substance were prepared at loading rates of 10, 100 and 1000 mg/L by weighing the test substance onto small polyethylene platelets and transferring these to the media preparation vessels (5 litre polyethylene flasks). The appropriate volume of dilution water was added and then the flask contents were then shaken (130 rpm) for 20 hours. The vessels were then transferred into a constant temperature water bath before introducing the fish.

- Controls: Dilution water

- Evidence of undissolved material: undissolved test material was observed to be present in the test vessels.
Test organisms (species):
Danio rerio (previous name: Brachydanio rerio)
Details on test organisms:

- Common name: Zebra fish

- Source: Aquafarm Ryba, Zeven, Germany

- Length at study initiation: approximately 3 cm


- Acclimation period: no data

- Acclimation conditions (same as test or not): no data

- Type and amount of food: no data

- Feeding frequency: no data

- Health during acclimation (any mortality observed): no data
Test type:
Water media type:
Limit test:
Total exposure duration:
96 h
no data
Test temperature:
Dissolved oxygen:
7.7-8.0 mg/L
Nominal and measured concentrations:
Nominal concentrations: 0(Control), 10, 100 and 1000 mg/L.

The measured concentrations of test substance in the 1000 mg/L treatment measured on one occasion ranged between 185-220 mg/L in fresly prepared medium and 64-150 mg/L in 24-h old medium. These concentrations exceed the solubility of the test substance. The test results are presented and interpreted with reference to nominal loading rate.
Details on test conditions:

- Test vessel: Flask

- Type: open

- Material, size, fill volume: Polyethylene, 5 litre with 5 litre fill volume

- Aeration: yes

- Renewal rate of test solution (frequency/flow rate): daily

- No. of organisms per vessel: 3 fish in 10 and 100 mg/L treatments, 7 fish in 1000 mg/L treatment and Control

- No. of vessels per concentration (replicates): 1

- No. of vessels per control (replicates): 1


- Source/preparation of dilution water: Drinking water consistent with OECD 203 test guideline

- Intervals of water quality measurement: Daily


- Adjustment of pH: adjusted to pH 7.0 twice per day using 1M HCl

- Photoperiod: no data

- Light intensity: no data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mortality after 24, 48, 72 and 96 hours.


- Spacing factor for test concentrations: 10

- Justification for using less concentrations than requested by guideline: the test design was a combined range-finding and limit test

- Range finding study: yes

- Test concentrations: 10, 100 and 1000 mg/L loading rates

- Results used to determine the conditions for the definitive study: no effects at 1000 mg/L
Reference substance (positive control):
96 h
Dose descriptor:
Effect conc.:
> 1 000 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
96 h
Dose descriptor:
Effect conc.:
>= 1 000 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Details on results:
- Mortality of control: 0

- Effect concentrations exceeding solubility of substance in test medium: Test media were dispersions and undissolved test material was observed to be present.
Reported statistics and error estimates:
No toxic effects were observed in the test and therefore statistical analysis of the results was not required.
Sublethal observations / clinical signs:

No effects were observed in the test

Validity criteria fulfilled:
A test medium prepared at a nominal loading rate 1000 mg/L of the test substance was not acutely toxic to Brachydanio rerio over 96 hours (96-h LL50: >1000 mg/L). A NOELR of ≥1000 mg/L was determined in the same test.

Description of key information

LL50 (96 h): > 1000 mg/l test mat. (nominal, highest concentration tested) based on mortality of Danio rerio (reported as: Brachydanio rerio) (OECD Guideline 203 (Fish, Acute Toxicity Test)).

Key value for chemical safety assessment

Additional information

A 96-hour LL50 value of >1000 mg/l has been determined for the 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 mortality of Danio rerio (reported as Brachydanio rerio), in a test conducted according to OECD TG 203 and in compliance with GLP (Evonik Degussa, 1998a). A supporting study reported a 48-hour LL50 > 130 mg/l test mat. (dispersion) (nominal) was obtained with Oryzias latipes (Evonik Degussa, 1999).

In both tests, 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.

The key study was selected because it was obtained in accordance with a standard guideline method for the endpoint and was assigned a higher reliability rating.