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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
Study period:
28-jul-2009 to 19-aug-2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study has been performed according to OECD and/or EC guidelines and according to GLP principles.
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
Qualifier:
according to
Guideline:
ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
The batch of 2 -sec-butylphenol tested was a clear colourless liquid with a purity of 99.6%.
Analytical monitoring:
yes
Details on sampling:
- Concentrations: all test concentrations and the control
- Sampling method: volume, 2 ml from the approximate centre of the test vessels at t=0 h and t=48 h
- Sample storage conditions before analysis: Samples were stored in a freezer until analysis
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Preparation of test solutions started with the highest concentration of 100 mg/l. No special treatment other than a short period of magnetic stirring (15 minutes) was applied to completely dissolve this concentration in test medium. The lower test concentrations were prepared by subsequent dilution. The final test solutions were all clear and colourless.

Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Source: In-house laboratory culture
- Age at study initiation: < 24 hours
- Method of breeding: With newborn daphnids, i.e. less than 3 days old, by placing about 250 of them into 5 litres of medium in an all-glass culture vessel.
- Feeding during test: No

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
180 mg/l expressed as CaCO3
Test temperature:
Between 19.1 and 20.0°C
pH:
At t=0 h: 7.6
At t=48 h: 7.9
Dissolved oxygen:
At t=0 h: 8.9-9.0
At t=48 h: 9.0
Nominal and measured concentrations:
Combined limit test/Range-finding:
Nominal concentrations: 0.1, 1, 10 and 100 mg/l
Measured concentration of 1 mg/l:
At t=0 h: 98 % of nominal
At t=48 h: 97 % of initial
Final test
Nominal concentrations: 1, 1.8, 3.2, 5.6 and 10 mg/l
Measured concentrations:
At t=0 h: 101 to 104 % of nominal
At t=48 h: 97 to 102 % of initial

Details on test conditions:
- Test vessel: 100 ml, all glass
- Type (delete if not applicable): open - ~80 ml,
- Material, size, headspace, fill volume: glass, 100 ml, normal headspace
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Adjusted ISO medium
- Culture medium different from test medium: yes, for culturing M7 medium is used

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours photoperiod daily

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : EC50 daily

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8
- Test concentrations: 1, 1.8, 3.2, 5.6 and 10 mg/l


Reference substance (positive control):
yes
Remarks:
potassium dichromate (K2Cr2O7)
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
1.8 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
3.7 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% confidence interval between 3.4 and 4.3 mg/l
Details on results:
- Behavioural abnormalities: no
- Mortality of control: no
- Other adverse effects control: no

Results with reference substance (positive control):
- Results with reference substance valid? Yes
- EC50/LC50:
The 24h-EC50 was 0.84 mg/l with a 95% confidence interval between 0.78 and 0.94 mg/l.

The 48h-EC50 was 0.75 mg/l with a 95% confidence interval between 0.56 and 1.0 mg/l.

Validity criteria fulfilled:
yes
Conclusions:
2-sec-butylphenol did not induce acute immobilisation of Daphnia magna at 1.8 mg/l after 48 hours of exposure (NOEC).

The 48h-EC50 was 3.7 mg/l based on analytically confirmed nominal exposure concentrations (95% confidence interval between 3.4 and 4.3 mg/l).
Executive summary:

A study was perform to assess the acute toxicity in Daphnia magna of the test material 2 -sec-butylphenol. The method followed the OECD Guidelines No. 202, 2004. In addition, the procedures were designed to meet the test methods of the Commission regulation (EC) No 440/2008, Part C.2, 2008 and the ISO International Standard 6341, 1996.

The batch of 2 -sec-butylphenol tested was a clear colourless liquid with a purity of 99.6% and completely soluble in test medium at the concentrations tested.

Preparation of test solutions started with the highest concentration of 100 mg/l. No special treatment other than a short period of magnetic stirring (15 minutes) was applied to completely dissolve this concentration in test medium. The lower test concentrations were prepared by subsequent dilution.

A final test was performed based on the results of a preceding combined limit/range-finding test. Twenty daphnia per test group (4 vessels, 5 per vessel) were exposed to a control and nominal 2 -sec-butylphenol concentrations of 1.0, 1.8, 3.2, 5.6 and 10 mg/l. Samples for analytical confirmation of actual exposure concentrations were taken at the start and at the end of the 48 -hour test period.

Analyses showed that the measured concentrations were in agreement with nominal and stable during the 48 -hour test period (100 -104%).

The study met the acceptability criteria prescribed by the protocol and was considered valid.

2 -sec-butylphenol did not induce acute immobilisation of Daphnia magna at 1.8 mg/l after 48 hours of exposure (NOEC).

The 48 -EC50 was 3.7 mg/l based on analytically confirmed nominal exposure concentrations (95% confidence interval between 3.4 and 4.3 mg/l).

Description of key information

2 -sec-butylphenol did not induce acute immobilisation of Daphnia magna at 1.8 mg/l after 48 hours of exposure (NOEC).
The 48 -EC50 was 3.7 mg/l based on analytically confirmed nominal exposure concentrations (95% confidence interval between 3.4 and 4.3 mg/l).

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
3.7 mg/L

Additional information

A study was perform to assess the acute toxicity in Daphnia magna of the test material 2 -sec-butylphenol. The method followed the OECD Guidelines No. 202, 2004. In addition, the procedures were designed to meet the test methods of the Commission regulation (EC) No 440/2008, Part C.2, 2008 and the ISO International Standard 6341, 1996.

The batch of 2 -sec-butylphenol tested was a clear colourless liquid with a purity of 99.6% and completely soluble in test medium at the concentrations tested.

Preparation of test solutions started with the highest concentration of 100 mg/l. No special treatment other than a short period of magnetic stirring (15 minutes) was applied to completely dissolve this concentration in test medium. The lower test concentrations were prepared by subsequent dilution.

A final test was performed based on the results of a preceding combined limit/range-finding test. Twenty daphnia per test group (4 vessels, 5 per vessel) were exposed to a control and nominal 2 -sec-butylphenol concentrations of 1.0, 1.8, 3.2, 5.6 and 10 mg/l. Samples for analytical confirmation of actual exposure concentrations were taken at the start and at the end of the 48 -hour test period.

Analyses showed that the measured concentrations were in agreement with nominal and stable during the 48 -hour test period (100 -104%).

The study met the acceptability criteria prescribed by the protocol and was considered valid.