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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:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Analytical monitoring in the test setups with fish delivered unclear results. This does not invalidate the overall significance of the results.
according to guideline
OECD Guideline 203 (Fish, Acute Toxicity Test)
GLP compliance:
Specific details on test material used for the study:
- Source and lot/batch No.of test material: 104663
- Purity: 98.9%

White powder
Test substance is not volatile
Analytical monitoring:
Details on sampling:
- Concentrations: Samples from vessels with nominal concentrations of 1.05, 0.32 and 0.1 mg/L test substance were taken at 0, 24, 48, 72 and 96 hours
Test organisms (species):
Danio rerio (previous name: Brachydanio rerio)
Details on test organisms:
- Common name: Zebrafish
- Source: Fischzucht Krämers, D-42781 Haan, Germany
- Length at study initiation: 2 +/- 1 cm

- Acclimation period: Acclimation to the test conditions eight days prior to test start, daily feeding until one day before test start
- Type and amount of food during acclimation: Tetra AniMin, Tetra Werke, Melle, Germany
- Feeding frequency during acclimation: 5 times / week
Test type:
Water media type:
Limit test:
Total exposure duration:
96 h
No data
Test temperature:
20.5 – 21.3 °C
7.2 – 7.6
Dissolved oxygen:
7.9 – 8.8 mg/L
No data
Nominal and measured concentrations:
Initial concentrations: Control, 0.1, 0.18, 0.32, 0.58, 1.05 mg/L
Actual concentrations: Two measurements were performed to monitor the test substance concentration in the test aquaria. The first measurement was performed in parallel to the test, but gave inconsistent results with far too high recoveries. A second measurement was then performed on frozen samples but the results appear also unreliable.
Analyses from a blank aquarium (without fish) revealed time-dependent depletion to 47% of the initial value after 96 h. These results are in accordance with a fully reliable analytical monitoring procedure.
Details on test conditions:
- Test vessel: 10 L-aquaria, filled with 7 L medium
- Aeration: No data
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- Biomass loading rate: 0.63 g fish /L

- Source/preparation of dilution water: Reconstituted water as given in guideline OECD 203
- Culture medium different from test medium: Yes, flow-through system using tap water

- Adjustment of pH: No
- Photoperiod: 12:12 hours light:dark cycle
- Light intensity: No data

Mortality. After 3, 24, 48, 72, and 96 hours mortality, pH and oxygen content were recorded
Reference substance (positive control):
not required by guideline
96 h
Dose descriptor:
Effect conc.:
0.18 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Key result
96 h
Dose descriptor:
Effect conc.:
0.18 - 0.32 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
96 h
Dose descriptor:
Effect conc.:
0.58 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Details on results:
- Behavioural abnormalities: In the medium dose group (0.32 mg/L) slower movements and orientation to the ground was observed after 24 and 48 hrs.
- Mortality of control: none
Reported statistics and error estimates:
Calculation of median effect concentration (EC50) after 24, 48, 72 and 96 hours, referring to nominal and measured concentrations
Validity criteria fulfilled:
The test results indicate that octenidine dihydrochloride is acutely toxic towards fish.
Executive summary:

The test was performed according to the OECD guideline 203 (1984).Brachidanio rerio(Zebrafish) was used as test organism.Seven fish were exposed to each of the five nominal concentrations of the test substance between 0.1 and 1.05 mg/L and to a control. The test was performed at 21 °C and 12:12 hours light: dark cycle in an artificial medium according to the guideline. Test duration was 96 hours and survival was assessed every 24 hours. pH, dissolved oxygen and test substance concentrations were measured in the same intervals.

Octenidine dihydrochloride was found to be acutely toxic towards fish. A clear concentration-response relationship can be deduced from the study results.All validity criteria according the test guideline OECD 203 are met within the study.

Analytical monitoring of the actual test concentrations in vessels with fish gave inconsistent and unsatisfactory results due to unknown reasons. Analysis of concentrations in a blank vessel without fish revealed time-dependent depletion to 47% of the initial value after 96 h. This percentage is in accordance with the results from a fully reliable analytical procedure. Subsequently, the geometric mean of the measured initial (0 h) and final percent values (96 h) is used as an average value of octenidine dihydrochloride exposition over the test duration of 96 h:


Mean average concentration = 67.9% of nominal concentration

The decreasing concentrations cannot be ascribed to volatility or hydrolysis, as octenidine dihydrochloride is non-volatile and stable in aequeous solution. Another possibility is adsorption to glass container walls, therefore the results from the blank vessel without fish can reliably be used as an estimate for non-biological adsorption.


0.122 mg/L (measured average)

(calculation 0.18 mg/L * 0.679 =0.122 mg/L)


> 0.122 mg/L but < 0.217 mg/L (measured average)

(calculation 0.18 mg/L * 0.679 = 0.122 mg/L ;
0.32 mg/L * 0.679 = 0. 217 mg/L )

We propose to be use the arithmetic mean of 0.122 mg/L and 0.217 mg/L as LC50 :

LC50= 0.17 mg/L


0.394 mg/L (measured average)

(calculation 0.58 mg/L * 0.679 = 0.394 mg/L)

Description of key information

In a study on the acute toxicity of octenidine dihydrochloride towards fish the LC50 was determined to be between 0.122 and 0.217 mg/L (arithmetic mean = 0.17 mg/L), employing the zebrafish (Brachydanio rerio) as the test organism.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
0.17 mg/L

Additional information

Analytical monitoring of the test substance was performed during this study. However, for unknown reasons results from vessels with organisms delivered inconsistent and unreliable results. Therefore, measured concentrations refer to the results from blank vessels without organisms, which were set up in parallel to the biotests.