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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose for cross-reference:
reference to same study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Concentrations:0, 4.6, 10, 22, 46, 100 mg/L (nominal)
- Sampling method: Samples for concentration control analysis were taken from each freshly prepared solution (0 h and 24 h) in additionally prepared vessels without daphnids and at the end of each exposure interval (after approx. 24 h and 48 h) from all test vessels with mobile daphnids and the lowest concentration with 100% immobilisation (pooled replicates).
- Sample storage conditions before analysis: Samples were immediately cooled on ice after collection. The samples were transported cooled on ice to the Analytical Laboratory on the day of sampling.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- The test solutions were prepared separately by directly adding test substance to test medium and stirring in a closed 1L volumetric flask for approximately 20 min at 20 ± 2 °C until visibly dissolved. Test concentrations 4.6, 10, 22 and 46 mg/L were visibly clear over the exposure period. Test concentration 100 mg/L showed optical inhomogeneity (streaks) on the surface directly after preparation, but was visibly clear over the exposure period.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna STRAUS
- Source: The clone of Daphnia magna STRAUS 1820 used was supplied by the Institut National de Recherche Chimique Appliquée,
France, in 1978. From this date on this clone was cultured and bred continuously in the Ecotoxicology Laboratory of Experimental Toxicology and
Ecology, BASF SE, Ludwigshafen Germany.
- Age at study initiation (mean and range, SD): < 24 hours (at least 3rd brood progeny)
- Feeding during test: No feeding during the exposure period.

ACCLIMATION
- The Daphnia are cultured under the identical conditions as the test including test media (Elendt M4), water quality, and temperature (20 ±1°C).

Test type:
other: static-renewal exposure via test water
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
2.34
Test temperature:
19.6 – 20.3°C (continuous monitoring)
pH:
7.7-7.9
Dissolved oxygen:
8.3-8.9 mg/L
Nominal and measured concentrations:
Nominal: 0 (control), 4.6, 10, 22, 46, 100 mg/L
Mean measured concentrations: 0 (control), 6.81, 10.7, 19.7, 42.4, 89.5 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Test tubes (glass) sealed with gas impermeable Teflon caps. (nominal volume 23 mL)
- Material, size, headspace, fill volume: approx. 23 mL, the test vessels were completely filled
- Type (delete if not applicable): closed
- Aeration: none
- Renewal rate of test solution (frequency/flow rate): Static-renewal exposure via test water.
- No. of organisms per vessel: 5 animals
- No. of vessels per concentration (replicates): 4 replicates with test animals (5 animals per replicate)
- No. of vessels per control (replicates): 1
- Biomass loading rate: 5 animals / test vessel (0.2 animals/mL)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: A synthetic fresh water (Elendt M4) is used as media for culture and test purposes. For the composition of this M4 medium see OECD 202.
- Total organic carbon: < 2 mg/L
- Ca/mg ratio: about 4 : 1
- Conductivity: 550 - 650 μS/cm


OTHER TEST CONDITIONS
- Adjustment of pH: No adjustment of the pH during the test.
- Light intensity: About 161 – 664 lux at a wave length of 400 -750 nm; 16 hours light : 8 hours darkness

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Each test vessel was visually checked for immobilized daphnids after 0, 24 and 48 hours. In addition any abnormal behavior or appearance was documented. For test renewal, daphnids in each replicate were captured with a wide bore pipette and transferred into test vessels with fresh test solution. Throughout the test, the appearance of the test solutions and dissolution behavior of the test substance was observed and recorded daily in old and new test solutions. The chemical and physical parameters of the test medium (total hardness, acid capacity, pH and conductivity) were determined after aeration and prior to use in the test.
The pH and oxygen content of the test solutions was measured after 0h and 24h (new test solutions) in an additional replicate without daphnids and after 24 h and 48h (old test solutions) in replicate 1 of each tested concentration. In addition, temperature was measured continuously during the whole exposure period in a separate vessel filled with water proximal to the test vessels.

TEST CONCENTRATIONS

- Test concentrations: In a preliminary range finding test (experimental conduct in accordance with GLP but without a GLP status) the 48 hour
EC50 was between 10 and 38 mg/L. However, in a first experiment (with GLP status) the 48-h EC50 was >40 mg/L.
The concentrations for this study were selected in accordance with the requirements set forth in the test guidelines and based on the results of the first experiment (experimental conduct in accordance with GLP, with a GLP status).
Reference substance (positive control):
yes
Remarks:
potassium dichromate (K2Cr2O7)
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
11.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 9.4-13.9 mg/L
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
12.1 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 10.5-13.9 mg/L
Details on results:
Since the measured concentrations deviated markedly from the nominal concentrations, the effect concentration, which is based on the mean measured concentrations should be preferably used for the evaluation of the test substance.
Results with reference substance (positive control):
Tests with a reference substance, potassium dichromate (K2Cr2O7), are conducted monthly. Reference substance tests are conducted according to OECD 202 guidelines and in accordance with GLP, but without a GLP status.
The EC50(24h) of the reference substance potassium dichromate was 1.06 mg/L (experiment date: 09 Feb 2012, project number: 50E0063/043039).
This result is within the range of 0.6 – 2.1 mg/L (ISO 6341) and indicates that the culture of Daphnia magna used in this study is responding normally to toxic stress.
Validity criteria fulfilled:
yes
Conclusions:
The nominal EC50 (mobility) of the test item on Daphnia magna is 11.4mg/L.
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The structures of the target and source substances are identical and differ only with respect to the ratio of enantiomers where the target substance is a single pure L-isomer and the source substance is an equimolar mixture of L and D isomers.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target substance, L-Citronellyl nitrile, is a mono-constituent substance (EC No. 695-909-8, CAS no. 35931-93-2).
The source substance, DL-Citronellyl nitrile, is a mono-constituent substance (EC No. 257-288-8, CAS no. 51566-62-2).
The source and target substances are both of high purity with a low concentration of impurities.

3. ANALOGUE APPROACH JUSTIFICATION
The read across hypothesis is based on structural similarity where the only difference between target and source molecules is the enantiomeric ratio. In a non-chiral environment the target and source chemicals will have identical properties but in the chiral environment of living organisms the enantiomers may possess different carcinogenicity and teratogenicity (in a chiral environment, stereoisomers might experience selective absorption, protein binding, transport, enzyme interactions and metabolism, receptor interactions, and DNA binding). Therefore, as a precaution for the developmental toxicity endpoint it is suggested that the NOAEL 250 mg/kg bw/day for L-Citronellyl nitrile is used instead of 500 mg/kg bw/day, as it is not known which form is more potent in vivo. All other endpoints are considered to be acceptable for this substance assuming that 50% of the target compound is available in the test material.

4. DATA MATRIX
Please refer to the data matrix included in the read-across justification document attached in Section 13.2.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Concentrations:0, 4.6, 10, 22, 46, 100 mg/L (nominal)
- Sampling method: Samples for concentration control analysis were taken from each freshly prepared solution (0 h and 24 h) in additionally prepared vessels without daphnids and at the end of each exposure interval (after approx. 24 h and 48 h) from all test vessels with mobile daphnids and the lowest concentration with 100% immobilisation (pooled replicates).
- Sample storage conditions before analysis: Samples were immediately cooled on ice after collection. The samples were transported cooled on ice to the Analytical Laboratory on the day of sampling.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- The test solutions were prepared separately by directly adding test substance to test medium and stirring in a closed 1L volumetric flask for approximately 20 min at 20 ± 2 °C until visibly dissolved. Test concentrations 4.6, 10, 22 and 46 mg/L were visibly clear over the exposure period. Test concentration 100 mg/L showed optical inhomogeneity (streaks) on the surface directly after preparation, but was visibly clear over the exposure period.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna STRAUS
- Source: The clone of Daphnia magna STRAUS 1820 used was supplied by the Institut National de Recherche Chimique Appliquée,
France, in 1978. From this date on this clone was cultured and bred continuously in the Ecotoxicology Laboratory of Experimental Toxicology and
Ecology, BASF SE, Ludwigshafen Germany.
- Age at study initiation (mean and range, SD): < 24 hours (at least 3rd brood progeny)
- Feeding during test: No feeding during the exposure period.

ACCLIMATION
- The Daphnia are cultured under the identical conditions as the test including test media (Elendt M4), water quality, and temperature (20 ±1°C).

Test type:
other: static-renewal exposure via test water
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
2.34
Test temperature:
19.6 – 20.3°C (continuous monitoring)
pH:
7.7-7.9
Dissolved oxygen:
8.3-8.9 mg/L
Nominal and measured concentrations:
Nominal: 0 (control), 4.6, 10, 22, 46, 100 mg/L
Mean measured concentrations: 0 (control), 6.81, 10.7, 19.7, 42.4, 89.5 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Test tubes (glass) sealed with gas impermeable Teflon caps. (nominal volume 23 mL)
- Material, size, headspace, fill volume: approx. 23 mL, the test vessels were completely filled
- Type (delete if not applicable): closed
- Aeration: none
- Renewal rate of test solution (frequency/flow rate): Static-renewal exposure via test water.
- No. of organisms per vessel: 5 animals
- No. of vessels per concentration (replicates): 4 replicates with test animals (5 animals per replicate)
- No. of vessels per control (replicates): 1
- Biomass loading rate: 5 animals / test vessel (0.2 animals/mL)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: A synthetic fresh water (Elendt M4) is used as media for culture and test purposes. For the composition of this M4 medium see OECD 202.
- Total organic carbon: < 2 mg/L
- Ca/mg ratio: about 4 : 1
- Conductivity: 550 - 650 μS/cm


OTHER TEST CONDITIONS
- Adjustment of pH: No adjustment of the pH during the test.
- Light intensity: About 161 – 664 lux at a wave length of 400 -750 nm; 16 hours light : 8 hours darkness

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Each test vessel was visually checked for immobilized daphnids after 0, 24 and 48 hours. In addition any abnormal behavior or appearance was documented. For test renewal, daphnids in each replicate were captured with a wide bore pipette and transferred into test vessels with fresh test solution. Throughout the test, the appearance of the test solutions and dissolution behavior of the test substance was observed and recorded daily in old and new test solutions. The chemical and physical parameters of the test medium (total hardness, acid capacity, pH and conductivity) were determined after aeration and prior to use in the test.
The pH and oxygen content of the test solutions was measured after 0h and 24h (new test solutions) in an additional replicate without daphnids and after 24 h and 48h (old test solutions) in replicate 1 of each tested concentration. In addition, temperature was measured continuously during the whole exposure period in a separate vessel filled with water proximal to the test vessels.

TEST CONCENTRATIONS

- Test concentrations: In a preliminary range finding test (experimental conduct in accordance with GLP but without a GLP status) the 48 hour
EC50 was between 10 and 38 mg/L. However, in a first experiment (with GLP status) the 48-h EC50 was >40 mg/L.
The concentrations for this study were selected in accordance with the requirements set forth in the test guidelines and based on the results of the first experiment (experimental conduct in accordance with GLP, with a GLP status).
Reference substance (positive control):
yes
Remarks:
potassium dichromate (K2Cr2O7)
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
11.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 9.4-13.9 mg/L
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
12.1 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 10.5-13.9 mg/L
Details on results:
Since the measured concentrations deviated markedly from the nominal concentrations, the effect concentration, which is based on the mean measured concentrations should be preferably used for the evaluation of the test substance.
Results with reference substance (positive control):
Tests with a reference substance, potassium dichromate (K2Cr2O7), are conducted monthly. Reference substance tests are conducted according to OECD 202 guidelines and in accordance with GLP, but without a GLP status.
The EC50(24h) of the reference substance potassium dichromate was 1.06 mg/L (experiment date: 09 Feb 2012, project number: 50E0063/043039).
This result is within the range of 0.6 – 2.1 mg/L (ISO 6341) and indicates that the culture of Daphnia magna used in this study is responding normally to toxic stress.
Validity criteria fulfilled:
yes
Conclusions:
The nominal EC50 (mobility) of the test item on Daphnia magna is 11.4mg/L.

Description of key information

This endpoint was fulfilled using read across from 3,7-dimethyloct-6-enenitrile (EC 257-288-8 / CAS 51566-62-2), for which the following results were obtained. The short-term toxicity to aquatic invertebrates was assessed according to test guideline OECD 202. The nominal EC50 (mobility) of the test item on Daphnia magna is 11.4 mg/L.

The EC50 based on mean measured concentrations is 12.1 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
11.4 mg/L

Additional information