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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:
from 29-OCT-2007 to 11-JAN-2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: The concentration of the test item Dimethyl 2-methyl glutarate was analytically measured in the duplicate test medium samples of the single test concentration taken at the start and the end of the test. From the control, one of the duplicate samples was analyzed from each of the sampling times.
- Sampling method: Duplicate samples were taken from each treatment before the start of the test and at the end of the test after 48 hours. For the 48-hour stability samples, the contents of the respective replicates were combined prior to sampling.
- Sample storage conditions before analysis: Immediately after sampling, all samples were stored deep-frozen (at about -20°C). The stability of the test item in samples under the storage conditions was confirmed in a pre-experiment (non-GLP).
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method:
The test medium was prepared by dissolving 50.2 mg of test item completely in 500 ml of test water using ultrasonic treatment for 15 minutes and intense stirring for 20 minutes at room temperature. The test medium was prepared just before introduction of the daphnids (i.e., start of the test).
- Controls: test water without addition of the test item
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain: defined by the supplier as clone 5
- Source: originally supplied by the University of Sheffield / UK in 1992. Since that time, the clone has been bred at RCC Laboratories
- Age at study initiation (mean and range, SD): the organisms used in the test were 6-24 hours old and were not first brood progeny.
- Weight at study initiation (mean and range, SD): no data
- Length at study initiation (length definition, mean, range and SD): no data
- Method of breeding: in reconstituted water of the quality identical to the water quality used in the tests (in respect to pH, main ions, and total hardness) and under temperature and light conditions identical to those of the tests
- Feeding during test : no

ACCLIMATION
- Acclimation period: no

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
2.5 mmol/L (= 250 mg/L as CaCO3)

Test temperature:
20°C

pH:
7.7

Dissolved oxygen:
8.3-8.7 mg/L

Salinity:
not applicable

Nominal and measured concentrations:
Nominal concentration : 100 mg/L

Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type: closed to reduce the loss of water by evaporation and to avoid the entry of dust into the solutions.
- Material, size, headspace, fill volume: The test was performed in 100-mL glass beakers filled with 50 mL of test medium.
- Aeration: The test water was aerated prior to the start of the study until oxygen saturation was reached, but was not aerated during the test period.
- Type of flow-through (e.g. peristaltic or proportional diluter): none (static test)
- Renewal rate of test solution (frequency/flow rate): no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 10 mL test medium per daphnia


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted test water according to ISO 6341 (ISO Standard 6341 (1996): Water quality - Determination of the inhibition of the mobility of Daphnia magna Straus (Cladocera, Crustacea) - Acute toxicity test) : analytical grade salts dissolved in purified water
- CaCl2 × 2H2O: 2.0 mmol/L (294 mg/L)
- MgSO4 × 7H2O: 0.5 mmol/L (123 mg/L)
- NaHCO3: 0.75 mmol/L (65 mg/L)
- KCl: 0.075 mmol/L (5.8 mg/L)
- Water hardness: 2.5 mmol/L (250 mg/L) as CaCO3
- Total organic carbon: no data
- Particulate matter: no data
- Metals, Pesticides, Chlorine: no data
- Alkalinity: 0.8 mmol/L
- Ca/mg ratio: 4:1 (based on molarity)
- Na/K ratio: 10:1 (based on molarity)
- Conductivity: no data
- Culture medium different from test medium: no
- Intervals of water quality measurement: At the start and at the end of the test, the pH values, the dissolved oxygen concentrations and the water temperature were determined at the single test concentration and in the control.
The appearance of the test media was visually recorded at the start of the test and after 24 and 48 hours.


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: A 16-hour light to 8-hour dark cycle with a 30 minute transition period was used.
- Light intensity: between approximately 490 and 650 Lux

EFFECT PARAMETERS MEASURED
The daphnids were observed for immobility after 24 and 48 hours of exposure (daphnids not being able to swim within 15 seconds after gentle agitation of the test beaker are considered to be immobilized).
The NOEC and EC0 were determined directly from the raw data.
The EC50 and the EC100 could not be determined due to the absence of a toxic effect of the test item in this test.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not relevant (limit test)
- Range finding study : yes
- Test concentrations: loading rate of 100 mg/L
- Results used to determine the conditions for the definitive study: no mortality at the undiluted loading rate.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
APPEARANCE OF THE TEST MEDIUM
No remarkable observations were made concerning the appearance of the test medium. The test medium was a clear solution throughout the whole test duration.

ANALYTICAL MONITORING
The measured concentration of the test item in the test medium at the start and the end of the test was 98 and 81% of the nominal value, respectively. Thus, the test item was sufficiently stable during the test period of 48 hours.

BIOLOGICAL RESULTS
In the control and in the test medium of the test item concentration of 100 mg/L, no immobilized daphnids were determined during the test period of 48 hours.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Mortality: no data
- 48 h EC50: 0.84 mg/L (acceptance range : 0.53-1.1 mg/L) (potassium dichromate)
For evaluation of the quality of the daphnia clone and the experimental conditions, potassium dichromate is tested as a positive control twice a year. The result of the latest positive control test in June 2007 (48 hour EC50: 0.84 mg/L, RCC Study No. B42704) indicated that the sensitivity of the test organisms was within the historical range of the RCC laboratory (48 hour EC50 from 1996 to 2007: 0.53 - 1.1 mg/L).


Reported statistics and error estimates:
None

Effect of Dimethyl 2-methyl glutarate on the Mobility of Daphnia magna:

Nominal test item concentration

(mg/L)

No. of

daphnids

tested

Immobilized

daphnids after

24 hours

          No.                   %

Immobilized

daphnids after

48 hours

          No.                   %

Control

20

0

0

0

0

100

20

0

0

0

0

Validity criteria fulfilled:
yes
Conclusions:
The test item Dimethyl 2-methyl glutarate no acute toxic effects on Daphnia magna up to the concentration of 100 mg/L.
Executive summary:

The acute toxicity of the test item Dimethyl 2-methyl glutarate to Daphnia magna was determined in a 48-hour static test according to the EU Commission Directive 92/69/EEC, Part C.2 (1992) and the OECD Guideline for Testing of Chemicals, No. 202 (2004).

Daphnids were exposed to control and test chemical at a nominal concentration of 100 mg/L for 48 hr. Mortality/immobilization were observed daily. 

In the control and in the test medium of the test item concentration of 100 mg/L, no immobilized daphnids were determined during the test period of 48 hours.

The 48-hour NOEC (highest concentration tested without toxic effects after the exposure period of 48 hours) and the 48-hour EC0 of Dimethyl 2-methyl glutarate to Daphnia magna were determined to be at least 100 mg/L. These values might even be higher but concentrations above 100 mg/L were not tested, in accordance with the test guidelines. The 48-hour EC50 and the 48-hour EC100 were clearly higher than 100 mg/L. These values could not be quantified due to the absence of toxicity of dimethyl 2-methyl glutarate at the test concentration of 100 mg/L.

Description of key information

The 48-hour EC50 (Daphnia magna) of Dimethyl 2-methyl glutarate was > 100 mg/L based on the mobility. Hence, Dimethyl 2-methyl glutarate is not harmful for the daphnids.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
100 mg/L

Additional information

One experimental study, scored as Klimisch 1, is available (Bätscher R., 2008) and selected as a key study.