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Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012-05-25 to 2012-05-29
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Qualifier:
according to
Guideline:
EU Method C.1 (Acute Toxicity for Fish)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Water samples (2 x 20 mL) for chemical analysis were taken of fresh test media at test start (before fish addition) at 48 h (aged test solution and newly prepared solution) and at test end.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
Due to the very low water solubility of the test item, a Water Accommodated Fraction (WAF) of the test item was applied.
A test preparation with a loading of 100 mg test item per litre was prepared according to the OECD guidance No. 23 and stirred slowly, using a star shape
magnetic stirring bar for about 48 h at room temperature (about 20°C).
Finally, the test preparation was filtered using a 0.2 μm filter (Sartolab 150v, PES-membrane, Sartorius Stedim Biotech S.A., Aubagne Cedex, France) to separate insoluble parts from the aqueous phase.
The filtrated WAF was used to prepare different diluted eluates.
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
TEST ORGANISM
- Strain: Oncorhynchus mykiss (Teleostei, Salmonidae)
- Source: Sauerländer Forellen GmbH, Saalhauser Straße 8, 57368 Lennestadt-Gleierbrück, Germany
- Age at study initiation (mean and range, SD):
- Length at study initiation (length definition, mean, range and SD): mean 4.6 cm, SD 0.2 cm
- Weight at study initiation (mean and range, SD): mean 0.98 g, SD 0.2 g
- Method of breeding: Fertilised eggs in eye-point stage were transferred to the fish holding device.
- Feeding during test
No feeding of the fish occurred during the test as well as 24 h before test start.

ACCLIMATION
- Acclimation period:
- Acclimation conditions (same as test or not): same as test conditions
- Type and amount of food: Fish were fed ad-libitum throughout the holding period with trout food daily.
- Health during acclimation (any mortality observed): The criteria of the test guideline were followed. Only healthy fish without diseases and abnormalities were used in the study. Mortality of the batch was less than 5 % during the last week before start of the study.

Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Post exposure observation period:
Mortality and clinical signs of the fish were recorded at 3 h, 24 h, 48 h, 72 h and 96 h after addition of the test solution.
Hardness:
Total hardness: 1.0 mmol/L
Test temperature:
The temperature was in the range of 15.3-15.5°C.
pH:
The pH in the test vessels was between 8.2 and 8.6, showed no influence of tellurium dioxide, and remained constant until the end of the study.
Dissolved oxygen:
The water was aerated to the point of oxygen saturation, in all test vessels between 99 % and 103 %.
Details on test conditions:
TEST SYSTEM
- Test vessel: full glass aquaria of 28 L with 20 L of test solution
- Aeration: slightly aerated via a glass capillary
- Type of flow-through (e.g. peristaltic or proportional diluter): A complete renewal of the test media was performed after 48 h.
- Renewal rate of test solution (frequency/flow rate):
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Purified drinking water
- Total organic carbon: DOC content - 0.7426 mg/L
- Total hardness: 1.1 mmol/L
- Metals: copper < 1.47 μg/L; iron < 2.92 μg/L ; manganese < 0.79 μg/L; zinc < 3.61 μg/L
- Chlorine: total residual chlorine < 0.02 mg/L
- Alkalinity: 1.6 mmol/L
- Conductivity: 234.8 µS/cm
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: light/dark cycle of 14/10 h


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortality and clinical signs (sub-lethal and abnormal behaviour) of the fish were recorded at 3 h, 24 h, 48 h, 72 h and 96 h after addition of the test solution.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 50 % serial dilution of the maximum nominal test concentration

- Range finding study
- Test concentrations: 100, 10 1 mg/L WAF
- Results used to determine the conditions for the definitive study:
Mortality was observed at the concentration of 100 mg/L after 48 h (one animal) 72 h (further 3 animals).
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 46.4 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Remarks:
Tellurium dioxide
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 37.1 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Remarks:
Tellurium
Basis for effect:
mortality
Details on results:
Neither clinical signs nor mortality were observed throughout the study.
The LC50 of tellurium dioxide was determined to be > 100 mg/L (nominal), corresponding to > 46.4 mg/L (mean measured).
Reported statistics and error estimates:
It was not possible to determine the LC50 because no mortality was observed. For the same reason no statistical evaluation was performed.
Validity criteria fulfilled:
yes
Conclusions:
The LC50 of tellurium dioxide was determined to be > 100 mg/L (nominal), corresponding to > 46.4 mg/L (mean measured).
Executive summary:

In a 96-h acute toxicity study, rainbow trout (Oncorhynchus mykiss) were exposed to tellurium dioxide at concentrations of 0, 6.25, 12.5, 25.0, 50.0, and 100.0 mg/L nominal under semic-static conditions. Each treatment consisted of seven fish.

Due to the very low water solubility of tellurium dioxide, a Water Accommodated Fraction (WAF) of the test item was applied.

The arithmetic means of measured concentrations were determined to be 0, 3.00, 6.05, 11.5, 24.2 and 46.4 mg tellurium dioxide/L, by ICP-MS.

Neither clinical signs nor mortality could be observed throughout the study.

The 96-h LC50 was:

> 100 mg tellurium dioxide/L (nominal)

> 46.4 mg tellurium dioxide (mean measured)

> 37.1 mg tellurium (mean measured)

All validity criteria for controls mentioned by the OECD guideline were met:

Mortality did not exceed 10 % in the controls at the end of the test.

The dissolved oxygen concentration was ≥ 60 % of the air saturation in the test vessels and control throughout the test.

Description of key information

Study was conducted according to Regulation (EC) No 440/2008: test method C. 1

Key value for chemical safety assessment

LC50 for freshwater fish:
46.4 mg/L

Additional information

In a 96-h acute toxicity study, rainbow trout (Oncorhynchus mykiss) were exposed to tellurium dioxide at concentrations of 0, 6.25, 12.5, 25.0, 50.0, and 100.0 mg/L nominal under semic-static conditions. Each treatment consisted of seven fish.

Due to the very low water solubility of tellurium dioxide, a Water Accommodated Fraction (WAF) of the test item was applied.

The arithmetic means of measured concentrations were determined to be 0, 3.00, 6.05, 11.5, 24.2 and 46.4 mg tellurium dioxide/L, by ICP-MS.

Neither clinical signs nor mortality could be observed throughout the study.

The 96-h LC50 was:

> 100 mg tellurium dioxide/L (nominal)

> 46.4 mg tellurium dioxide/L (mean measured)

> 37.1 mg tellurium/L (mean measured)