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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:
15 September - 18 September 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Fully documented study run under GLP and according to international guidelines.
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
Higher temperature in the main (21.6 to 22.4 °C) and reference study (22.1 to 22.2 °C) than stated in the guideline. As no immobility occurred in the control during the test, this deviation was stated as uncritical.
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
yes
Remarks:
Higher temperature in the main (21.6 to 22.4 °C) and reference study (22.1 to 22.2 °C) than stated in the guideline. As no immobility occurred in the control during the test, this deviation was stated as uncritical.
Qualifier:
according to
Guideline:
ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))
Deviations:
yes
Remarks:
Higher temperature in the main (21.6 to 22.4 °C) and reference study (22.1 to 22.2 °C) than stated in the guideline. As no immobility occurred in the control during the test, this deviation was stated as uncritical.
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Samples were taken after preparation of the treatments at the start of the test and at the end of the test and were filtrated with membrane filters (pore diameter 0.45 µm). The samples were measured directly. Each sample was measured at least in duplicate.
Vehicle:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna STRAUS
- Strain: Berlin
- Source: Umweltbundesamt Berlin
- Age at study initiation (mean and range, SD): Less than 24 hours
- Feeding during test: None


ACCLIMATION
- Acclimation period: 30 min
- Acclimation conditions (same as test or not): Same as test (just in daphnia medium)
- Health during acclimation (any mortality observed): Only animals which showed no apparent damage were used for the test.

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
250 mg CaCO3/L
Test temperature:
21.6 – 22.4 °C (deviation within the test ±1 °C)
pH:
7.5 - 7.7 after 48h
Dissolved oxygen:
7.5 - 8.6 mg/l after 48h. The concentration of dissolved oxygen stayed above 7.5 mg/L throughout the test.
Nominal and measured concentrations:
Nominal and measured concentrations: See table in "Any other information on materials and methods incl. tables"
Details on test conditions:
TEST SYSTEM
- Test vessel: closed glass vessels
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: total volume 130 mL
- Aeration: After preparation, the dilution water is aerated.
- No. of organisms per vessel: five
- No. of vessels per concentration (replicates): four
- No. of vessels per control (replicates): four


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Deionised water with an enrichment of certain minerals (as demanded in the guidelines) was used in the test.


OTHER TEST CONDITIONS
- Adjustment of pH: the pH of the dilution water was adjusted to 7.8 ±0.2.
- Photoperiod: no information available
- Light intensity: no information available

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : After 24 and 48 hours, the immobilised daphnia were counted. Daphnia are considered immobilised if they perform no movements or are only able to move their antennae when the beaker is gently agitated.
Reference substance (positive control):
yes
Remarks:
K2Cr2O7
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
47 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
dissolved
Remarks:
dissolved organic carbon
Basis for effect:
other: immobilisation
Duration:
24 h
Dose descriptor:
NOEC
Effect conc.:
31 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
dissolved
Remarks:
organic carbon
Basis for effect:
other: immobilisation
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
46 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
dissolved
Remarks:
dissolved organic carbon
Basis for effect:
other: immobilisation
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
31 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
dissolved
Remarks:
dissolved organic carbon
Basis for effect:
other: immobilisation
Duration:
24 h
Dose descriptor:
EC100
Effect conc.:
> 47 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
other: dissolved organic carbon
Basis for effect:
other: immobilisation
Duration:
48 h
Dose descriptor:
EC100
Effect conc.:
> 47 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
other: dissolved organic carbon
Basis for effect:
other: immobilisation
Details on results:
One concentration showed toxicity (75% immobilisation after 48 h). None of the animals were immobilised in the control.
Results with reference substance (positive control):
The 24h-EC50i of potassium dichromate was tested in a current reference test. The value was determined as 1.1 mg/L, lying within the demanded range of 0.6 – 1.7 mg/L.
Reported statistics and error estimates:
The estimation of the EC50 was accomplished using the software OriginTM. The calculated values for p resp. χ2 are given in the graph (see illustration). The data were evaluated using sigmoidal fit on a linear-logarithmic scale. If a sigmoidal fit is used, no confidence interval can be calculated. Since there was only one value between 0 % and 100 % immobility, a linear fit with a probability-y-axis could not be performed.

In the control, none of the daphnia died or showed any signs of abnormal behaviour throughout the test.

Immobilities

Nominal Concentration in mg/L

Immobility 24 hours

Immobility 48 hours

abs.

in %

abs.

in %

0

0

0

0

0

0

0

0

0

0

0

10

0

0

0

0

0

0

0

0

0

0

18

0

0

0

0

0

0

0

0

0

0

32

0

0

0

0

0

0

0

0

0

0

56

0

0

0

0

0

0

0

0

0

0

100

1

3

2

4

50

1

4

5

5

75

 

pH and O2, Temperature

The pH values in the test media and the control ranged from 7.5 to 7.7. The concentration of dissolved oxygen stayed above 7.5 mg/L throughout the test. Temperature range was 21.6 – 22.4 °C. The details are given in the following tables:

pH and O2-values

Nominal Concentration in mg/L

pH

O2-Concentration in mg/L

0 h

48 h

0 h

48 h

0

7.7

7.6

8.3

7.7

10

7.7

7.6

8.3

7.5

18

7.7

7.6

8.3

7.6

32

7.7

7.7

8.3

8.6

56

7.7

7.6

8.3

8.1

100

7.7

7.5

8.3

7.5

Temperature

Temperature in °C

0 h

24 h

48 h

22.4

22.0

21.6

Positive Control

The pH values in the test media and the control ranged from 7.6 to 7.8. The concentration of dissolved oxygen stayed above 7.3 mg/L throughout the test. Temperature range was 22.1 – 22.2 °C. The details are given in the following table

Immobilities, pH and O2-values

Nom. Conc. in mg/L

Immobility

pH

O2-Concentration in
mg/L

abs.

in %

t = 0 h

t = 24 h

t = 0 h

t = 24 h

0

0

0

0

0

0

7.7

7.8

8.4

7.4

0.5

0

0

0

0

0

7.7

7.8

8.3

7.3

0.625

0

0

0

0

0

7.7

7.8

8.3

7.3

1.0

0

2

0

2

20

7.7

7.8

8.3

7.3

1.25

3

5

4

3

75

7.7

7.8

8.3

7.4

1.5

4

5

4

4

85

7.6

7.8

8.1

7.2

2.0

5

5

5

5

100

7.6

7.8

8.1

7.5

2.5

5

5

5

5

100

7.6

7.7

8.1

7.5

3.0

5

5

5

5

100

7.6

7.6

8.0

7.5

 

Temperature

Temperature in °C

0 h

24 h

22.2

22.1

Biological Results Positive Control

Parameter

Value

95%-confidence interval

NOEC 24 h

0.625 mg/L

not determinable

24h EC50i

1.1 mg/L

not determinable

24h EC100i

2.0 mg/L

not determinable

 

Validity criteria fulfilled:
yes
Conclusions:
The following results were determined for the test item "2-propanol and 2-butanol production, distn. residues" (species: Daphnia magna): 24h-NOEC = 31 mg/L; 48h-NOEC = 31 mg/L; 24h-EC50i = 47 mg/L; 48h-EC50i = 46 mg/L.
Based on these data in combination with the fact that the substance is not readily biodegradable, a classification into aquatic chronic category 3 (H412) (corresponding to R52/53) is required (EC50 band: 10 - 100 mg/L).
Executive summary:

The 24h- and 48h-EC50i of "2-propanol and 2-butanol production, distn. residues" (main constituent 2,2'-oxybisbutane (DSBE), DIPE, SBA and 2 -methylpropan-2 -ol (TBA)) were determined against Daphnia magna Straus according to OECD 202 resp. EU C.2.

The experiment was performed using five concentrations ranging from 10 to 100 mg/L (nominal). Twenty daphnia were exposed to the test item for 48 hours in a static test system. As the test item is volatile, the study was performed in completely filled and closed vessels. After 24 and 48 hours, the immobilised daphnia were counted.

One concentration showed toxicity (75% immobilisation after 48 h). None of the animals were immobilised in the control.

The 24h-EC50i of potassium dichromate was tested in a current reference test. The value was determined as 1.1 mg/L, lying within the demanded range of 0.6 – 1.7 mg/L.

At the beginning and at the end of the test, the content of test item was determined by DOC-determination in the test solutions. The content of the test item was calculated from content of organic carbon of the test item (76%) The recovery after 48 hours ranged from 81 to 129% of the start concentration. The correlation between nominal and measured concentration was poor. Therefore, the geometric mean of the measured concentration was used for the determination of the biological results.

The following results were determined for the test item "2-propanol and 2-butanol production, distn. residues" (species: Daphnia magna):

24h-NOEC = 31 mg/L

48h-NOEC = 31 mg/L

24h-EC50i = 47 mg/L 

48h-EC50i = 46 mg/L 

Description of key information

The following results were determined for the test item "2-propanol and 2-butanol production, distn. residues" (main constituent 2,2'-oxybisbutane (DSBE), DIPE, SBA and 2 -methylpropan-2-ol (TBA)) (species: Daphnia magna): 24h-NOEC = 31 mg/L; 48h-NOEC = 31 mg/L; 24h-EC50i = 47 mg/L; 48h-EC50i = 46 mg/L

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
46 mg/L

Additional information

The EC50 value and the NOEC for the immobilisation of Daphnia magna of "2-propanol and 2-butanol production, distn. residues" (main constituent 2,2'-oxybisbutane (DSBE), DIPE, SBA and 2-methylpropan-2-ol (TBA)) was measured according to OECD 202, respectively EU C.2 guideline under GLP. The following results were obtained: 24h-NOEC = 31 mg/L; 48h-NOEC = 31 mg/L; 24h-EC50i = 47 mg/L; 48h-EC50i = 46 mg/L

The analytical determinations of the test item showed poor correlation between nominal and measured concentrations and acceptable recovery rates. This is probably attributable to the high volatility of the test item. Therefore, the determination of the results of the test item "2-propanol and 2-butanol production, distn. residues" was based on the geometric mean of the measured concentrations.

Based on these data in combination with the fact that the substance is not readily biodegradable, a classification into aquatic chronic category 3 (H412) according to the CLP regulation (corresponding to R52/53) is necessary (EC50 band 10 - 100 mg/L).

Based on the lowest EC50 value of three species daphnia, algae and fish (available studies), an aquatic PNEC value was calculated for the risk assessment.