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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
At the start of the final test, duplicate samples were taken from the vessel used for the fish test. Done to determine if the solution was homogenous. The study integrity was not adversely affected by the deviation.
GLP compliance:
yes
Specific details on test material used for the study:
Clear colourless liquid, purity 96.5%.
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
A stock solution of 100 pentamethyl-trioxepane was prepared in M7 medium after 15 min. of magnetic stirring.
Test organisms (species):
Daphnia magna
Details on test organisms:
In house laboratory culture with a known history. Each batch was started with daphnids < 3days old. 250 daphnids in 5L M7 medium in a glass vessel. Max. age 4 weeks. Medium temp. 18-22 °C. Feed: daily, suspension of fresh water algae

Age at study initiation: < 24 hours
Test type:
static
Water media type:
other: M7 medium
Remarks:
Tap water purified by reverse osmosis, milli-RO, from which ISO medium is prepared.; M7 medium is prepared with the ISO medium.
Limit test:
no
Total exposure duration:
48 h
Hardness:
250 mg/l pH: 8.0 ± 0.2 after aeration
Test temperature:
19.3 - 20.2 °C
pH:
7.9-8.0
Dissolved oxygen:
9.3
Nominal and measured concentrations:
Nominal concentrations:
Range-finding test: blank-control, 0.1, 1, 10 and 100 mg/l. final test: 100 mg/l

Measured concentrations:
Final test: T=0 not detected in control and 75.8 and 72.2 in the samples. T=48 not detected in control and 60.3 in sample and 48.6 in reserve sample. At the end of the test the conc. declined > 80% therefore further calculations were performed with the measured conc.
Details on test conditions:
see Any other information on materials and methods incl. tables
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
63 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
other: no daphnia became immobilized at any test conc.
Remarks on result:
other: also 24 h
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 63 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
other: no daphnia became immobilized at any test conc.
Remarks on result:
other: also 24 h
Details on results:
Range-finding test and final test: no daphnia became immobilized at any of the test concentrations.

The value of pentamethyl-trioxepane in solution measured at the end (48h) of the test in the sample and the reserve varies 60.3 mg/ml and 48.3 mg/ml. This variation may result from variability in the analytical method. Therefore the mean of these values is used for further calculations. The average exposure concentration was calculated to be 63 mg/l.

Control group: 20 daphnia, 5 per 80 ml test medium without the test substance or other additives vessel in quadruplicate.  

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the present study pentamethyl-trioxepane did not induce acute immobilization of Daphnia magna at 63 mg/l after 48 hours of exposure (NOEC). 24 & 48h-EC50 >63 mg/l.
Executive summary:

24 & 48h-EC50>63 mg/l.

Description of key information

Under the conditions of the present study pentamethyl-trioxepane did not induce acute immobilization of Daphnia magna at 63 mg/l after 48 hours of exposure (NOEC). 24 & 48h-EC50 >63 mg/l.

Key value for chemical safety assessment

Additional information