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Ecotoxicological information

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:
1989-08-03 - 1989-08-05
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Remarks:
Study performed according to local guideline (Austria) but not according to GLP. The study is well performed and the results can be considered reliable (Klimisch 2). Because the test was semi-static test substance loss is not expected to have occurred.
Qualifier:
according to guideline
Guideline:
other: öNORM M 6263, Teil 2 (semi-static test)
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
TEST ORGANISM
- Common name: rainbow trout
- Age at study initiation (mean and range, SD): not reported
- Length at study initiation (length definition, mean, range and SD): 4-6 cm (initially)
- Feeding during test: no
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
none
Hardness:
138.84 mg CaCO3/L (tap water)
Test temperature:
15°C
pH:
8.3 (in highest test concentration)
Dissolved oxygen:
not applicable (constant aeration)
Salinity:
not applicable
Nominal and measured concentrations:
Nominal: control + 1, 3, 10, 30, 40, 42, 48, 51, 54, 57, 58, 63, 67, 70, 85, 100, 300 g/L
Details on test conditions:
TEST SYSTEM
- Test vessel: glass aquarium, 25x17x17 (18x12x18) cm
- Aeration: continuous, 20 mL/min/L
- Renewal rate of test solution (frequency/flow rate): renewal after 24 h
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mortality after 48 h
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
31 200 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
recalculated to pure substance
Basis for effect:
mortality (fish)
Remarks on result:
other: confidence interval 26400-36000 mg/L
Details on results:
LC0 = 28800 mg/L
LC100 = 34800 mg/L
LOEC = 30600 mg/L
Reported statistics and error estimates:
not reported
Validity criteria fulfilled:
yes
Conclusions:
In this semi-static 48-h toxicity test with juvenile rainbow trout (Salmo gairdneri), an LC50 value of 31200 mg/L (pure substance) was obtained, indicating low toxicity of the substance.
Executive summary:

In a semi-static 48-h acute toxicity study, Salmo gairdneri (rainbow trout) were exposed to N-methylmorpholine oxide at nominal concentrations of 1, 3, 10, 30, 40, 42, 48, 51, 54, 57, 58, 63, 67, 70, 85, 100, 300 g/L. The 48-h LC50 was 31200 mg/L (nominal concentration).

The study was conducted according to national standards (Austria) but not GLP and is generally well documented. In summary, it satisfies the criteria for an acute toxicity study in fish. The study duration was shorter compared to the current OECD 203 guideline for testing short-term toxicity to fish (48 hours versus 96 hours). However, the concentrations tested were much higher than current guidelines advise for and therefore it can be assumed, that at lower, relevant concentrations effects will not be observed and fish will not be the most sensitive species. For these reasons and animal welfare reasons, repetition of the study is not necessary.

Results synopsis

Test organism: Salmo gairdneri (rainbow trout), length = 4-6 cm at study start

Test type: semi-static

LC50: 31200 mg/L (nominal concentration)

Endpoint(s) affected: Mortality

Description of key information

In a semi-static 48-h acute toxicity study, Salmo gairdneri (rainbow trout) were exposed to N-methylmorpholine oxide at nominal concentrations of 1, 3, 10, 30, 40, 42, 48, 51, 54, 57, 58, 63, 67, 70, 85, 100, 300 g/L. The 48-h LC50was 31200 mg/L (nominal concentration).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
31 200 mg/L

Additional information

Short-term toxicity of the test substance to fish was investigated by exposing Oncorhynchus mykiss (Rainbow trout) during 96 hours in a semi-static test, according to a local guideline (öNORM M 6263, Teil 2). This resulted in an LC50 value of 31200 mg/L.

The study duration was shorter compared to the current OECD 203 guideline for testing short-term toxicity to fish (48 hours versus 96 hours). However, the concentrations tested were much higher than current guidelines advise for and therefore it can be assumed, that at lower, relevant concentrations effects will not be observed and fish will not be the most sensitive species. For these reasons and animal welfare reasons, repetition of the study is not necessary.