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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)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
Samples were taken from the control and each test group (R1 and R2 replicates were pooled) at 0 and 48 hours for quantitative analysis.
Vehicle:
no
Details on test solutions:
200mg of test material was dissolved into reconstituted water and adjusted to a volume of 2 litres to give a 100 mg/l stock solution. Dilutions were made from this stock solution to generate test concentrations of 10, 18, 32 and 56 mg/l. Each concentration preparation was mixed by inversion to ensure homogeneity. The concentration and stability in each test preparation were verified by chemical analysis (at 0 and 48 hours).
Test organisms (species):
Daphnia magna
Details on test organisms:
The test was conducted using 1st instar Daphnia magna from in-house laboratory cultures.
TEST ORGANISM
- Common name: Daphnia magna
- Source: In-house laboratory cultures
- Age at study initiation (mean and range, SD): < 24 hours old
- Method of breeding: Reproduction was by parthenogenesis
- Feeding during test: none
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
250 mg/l CaCO3
Test temperature:
20 - 21 degrees C
pH:
7.9 - 8.1
Dissolved oxygen:
8.9 - 9.1 mg O2/l
Nominal and measured concentrations:
Nominal concentrations: 0, 10, 18, 32, 56 and 100 mg/l
Details on test conditions:
TEST SYSTEM
- Test vessel: 300ml glass conical flask
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 300 ml conical flask (with minimal headspace to restrict volatilisation loss).
- Aeration: none
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light and 8 hours darkness (with 20 minute dawn and dusk transition period)

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.010, 0.10, 1.0, 10 and 100 mg/l
- Results used to determine the conditions for the definitive study: yes (0, 10, 18, 32, 56 and 100 mg/l were used in the definitive test)
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
38 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL: 30 - 47 mg/l
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
47 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL: 40 - 55 mg/l
Duration:
24 h
Dose descriptor:
NOEC
Effect conc.:
18 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Details on results:
Analysis of the test concentrations at 0 and 48 hours confirmed measured test concentrations ranged from 96% to 108% of the nominal values and so the results have been based on nominal test concentrations only.
Results with reference substance (positive control):
The mean 48-h EC50 value calculated from all positive controls was 0.78 mg/l. The NOEC at 24 hours and 48 hours were 0.56 and 0.32 mg/l respectively (based on zero immobilisation at this concentration). These potassium dichromate positive control results were within the normal range for this reference material.
Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of this study the 48 hour EC50 is 38 mg/l and the NOEC is 10 mg/l.
Executive summary:

The acute toxicity of dihydromyrcenol to Daphnia magna was studied under static conditions.  Daphnids were exposed to test chemical at nominal concentrations of 0, 10, 18, 32, 56 and 100 mg/l (confirmed by analysis to have represent achieved concentrations) for 48 hours.  Mortality/immobilization or other adverse effects were observed daily.  The 48–hour EC50was 38 mg/l.  The 48–hr NOEC based on immobilization was 10 mg/l. 

 

Results Synopsis

 

Test Organism Age: 1st instar (<24 hours old)

Test Type: Static

 

48h EC50:  38 mg/l             

48h NOEL: 10 mg/l                       

Description of key information

Reliable experimental data with the test item are available to assess acute toxicity to daphnia magna. 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
38 mg/L

Additional information

A 48h EC50 value of 38 mg/l was obtained from the key study of the test item toxicity to aquatic invertebrates.This value correlates well with the acute toxicity to Daphnia magna study using the read-across analogue substance linalool which reports a 48h EC50 value of 59 mg/l (Linalool, OECD SIDS report, 2002).