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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)
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
Samples were taken from the control and each test concentration from the bulk test preparation at 0 hours and from the pooled replicates at 48 hours for quantitative analysis. All samples were stored frozen prior to analysis.
Vehicle:
no
Details on test solutions:
Reconstituted water (ISO medium) with following composition wasused for both the range-finding and definitive tests.

Ingredient
Final Concentration (mg/L)
H3BO3
0.715
MnCl2.4H2O
0.090
LiCl
0.077
RbCl
0.018
SrCl2.6H2O
0.038
NaBr
0.004
Na2MoO4.2H2O
0.016
CuCl2.2H2O
0.004
ZnCl2
0.013
CoCl2.6H2O
0.010
KI
0.0033
Na2SeO3
0.0022
NH4VO3
0.00058
Na2EDTA.2H2O
0.625
FeSO4.7H2O
0.249
CaCl2.2H2O
293.8
NaHCO3
64.8
MgSO4.7H2O
123.3
Na2SiO3.9H2O
10
KCl
5.8
NaNO3
0.274
K2HPO4
0.184
KH2PO4
0.143
Thiamine hydrochloride
0.075
Cyanocobalamine (vitamin B12)
0.0010
D(+) biotin (vitamin H)
0.00075
The pH of the prepared media was 7.9 ± 0.3 and stored at approximately 21 ºC.

Test organisms (species):
Daphnia magna
Details on test organisms:
The test was carried out using 1st instar Daphnia magna derived from in-house laboratory cultures.
Adult daphnia were maintained in 150 mL glass beakers containing ISO medium in a temperature controlled room maintaining the water temperature at 18 to 22 °C. The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods. Each culture was fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension. Culture conditions ensured that reproduction was by parthenogenesis. Gravid adults were isolated the day before initiation of the test, such that the young daphnids produced overnight were less than 24 hours old. These young were removed from the cultures and used for testing. The diet and diluent water are considered not to contain any contaminant that would affect the integrity or outcome of the study.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
No
Hardness:
See composition under Details on test solution
Test temperature:
18-22 C
pH:
7.9
Dissolved oxygen:
> 3 mg/l
Nominal and measured concentrations:
Analysis of the 56 and 100 mg/L test preparations at 0 hours showed measured test concentrations be near nominal.
Analysis of the 32 mg/L test preparation at 0 hours showed that a concentration of 74% of nominal was obtained. There was no significant
change in the measured concentrations at 48 hours. Given that concentrations at the NOEC and above were near nominal, it was considered
appropriate to base the results on the nominal test concentrations.
Details on test conditions:
Adult daphnia were maintained in 150 mL glass beakers containing Elendt M7 medium in a temperature controlled room maintaining the water temperature at 18 to 22 °C. The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods. Each culture was fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension. Culture conditions ensured that reproduction was by parthenogenesis. Gravid adults were isolated the day before initiation of the test, such that the young daphnids produced overnight were less than 24 hours old. These young were removed from the cultures and used for testing. The diet and diluent water are considered not to contain any contaminant that would affect the integrity or outcome of the study.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
56 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
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:
LOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
Range finding test
No immobilization was observed at the test concentration of 0.10 mg/L, however, immobilization was observed at 1.0, 10 and 100 mg/L.
Based on this information, test concentrations of 10, 18, 32, 56 and 100 mg/L were selected for the definitive test.
Chemical analysis of the 10 and 100 mg/L test preparations at 0 hours showed measured test concentrations to range from 86% to 89%
of nominal concentrations. There was no significant change in the measured concentrations at 48 hours indicating that the test
item was stable under test conditions.

Definitive Test
Verification of Test Concentrations
Analysis of the 56 and 100 mg/L test preparations at 0 hours (see Annex 5) showed measured test concentrations be near nominal. Analysis of the 32 mg/L test preparation at 0 hours showed that a concentration of 74% of nominal was obtained. There was no significant change in the measured concentrations at 48 hours. Given that concentrations at the NOEC and above were near nominal,it was considered appropriate to base the results on the
nominal test concentrations.

Immobilization Data
Analysis of the immobilization data by Probit analysis using Linear Maximum-Likelihood regression at 24 and 48 hours based on the nominal test
concentrations gave the following results: The No Observed Effect Concentrations after 24 and 48 hours exposure were 100 and
56 mg/L respectively. The Lowest Observed Effect Concentration after 48 hours exposure was 100 mg/L.

Sub-Lethal Effects
Sub-lethal effects of exposure were observed in all test concentrations. These responses were
trapping at the surface and reduced mobility (see Table 2).

Validation Criteria
The test was considered to be valid given that no more than 10% of the control daphnids
showed immobilization or other signs of disease or stress and that the oxygen concentration
at the end of the test was equal to or greater than 3 mg/L in the control and test vessels.

Water Quality Criteria
Water quality measurements confirm the water quality to be within required range. Temperature was maintained at approximately 22 °C throughout the test,
while there were no treatment related differences for oxygen concentration or pH.
Throughout the test the light intensity was observed to be in the range 507 to 522 Lux.

Observations on Test Item Solubility
At the start and throughout the test all control and test solutions were observed to be clear
colorless solutions.
Results with reference substance (positive control):
The results from the positive control with potassium dichromate were within the normal range for this reference item.
24 h EC50=1.3 ml/l
48 h EC50=1.2 mg/l
Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity of the chlorohexanol to the freshwater invertebrate Daphnia magna has been investigated using OECD 202 method and gave a 48-Hour EC50 value of greater than 100 mg/L. The No Observed Effect Concentration was 56 mg/L for 48 h exposure.
Executive summary:

The acute toxicity of the chlorohexanol to the freshwater invertebrate Daphnia magna has been investigated using OECD 202 method and gave a 48-Hour EC50 value of greater than 100 mg/L. The No Observed Effect Concentration was 56 mg/L for 48 h exposure.

Description of key information

The acute toxicity of the chlorohexanol to the freshwater invertebrate Daphnia magna has been investigated using OECD 202 method and gave a 48-Hour EC50 value of greater than 100 mg/L. The No Observed Effect Concentration was 56 mg/L for 48 h exposure.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
100 mg/L

Additional information