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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 2013-05-28 to 2013-07-25
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)
Version / remarks:
(Adopted: 13 April 2004)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: Testing Methods for New Chemical Substances, 2011.03.31, No. 0331-07, Ministry of Health, Labor and Welfare; 2011.03.29 No 5, Ministry of Economy, Trade and Industry; No. 110331009, Ministry of Environment, Japan; V. Daphnids acute immobilization test.
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
- Analytical purity: 100%
- Lot/batch No.: KNC110310
Analytical monitoring:
yes
Details on sampling:
- Concentrations: control, 10, 18, 32, 56, 100 mg/L
- Sampling method: An aliquot was taken from the remaining unused test solution of each test group at initiation and termination of the test. The samples were taken from mid-depth of each replicate without agitation.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A 0.12 g aliquot of a test substance was weighted. A stock solution was prepared by mixing the test substance with dilution water to volume 120 mg/L. Each test solution was prepared by diluting appropriate volumes of stock solution with the dilution water to volume 500 mL.
- Eluate: no
- Differential loading: no
- Controls: yes, test medium control
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Source: in-house culture (originally obtained from National Institute for Environmental Studies, Japan (Independent Administrative Institution): 28 Oct 1996)
- Age at study initiation: < 24 hours; females
- Feeding during test: none

ACCLIMATION
- Parental acclimation period: 14 d
- Parental acclimation conditions (same as test or not): same as test
- Type and amount of food: Commercial condensed live Chlorella vulgaris and YCT (suspended solution of yeast, dried alfalfa and Tetramin); amount: 0.1 - 0.2 mg C/daphnid/day depending on their reproductive activity.
- Health during acclimation (any mortality observed): mortality was below 5% (practically 3.8%)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
230 mg CaCO3/L, measured by Total hardness test kit HA-DT (HACH COMPANY Ltd.)
Test temperature:
20.0 - 20.8 °C, measured by Water temperature meter CT-460WR (Custom Corporation)
pH:
7.9, measured by pH meter D-51 (Horiba Ltd.)
Dissolved oxygen:
8.4 - 8.6 mg/L, measured by DO meter Model 58 (YSI/Nanotech Inc.)
Nominal and measured concentrations:
Nominal: 0, 10, 18, 32, 56, 100 mg/L
Measured: 0, 10, 18, 32.3, 56.0, 100 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 mL glass beakers closed with a lid (100 mL fill volume)
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: artificial dilution water, Elendt M4.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light / 8 h dark
- Light intensity: room lightning (6.18 - 9.22 µE/m²/s)

EFFECT PARAMETERS MEASURED: mobility and toxic symptoms after 24 and 48 h; DO and pH of the test solutions in all groups measured at initiation and termination of the exposure.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0, 10, 32, 100 mg/L
- Results used to determine the conditions for the definitive study: As the 48 hour EC50 in the range finding test was found to be around 100 mg/L, the definitive test was conducted at nominal concentrations of 10, 18, 32, 56 and 100 mg/L with a spacing factor of 1.8.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities: Immobilization was not observed, apart from the concentration 100 mg/L after 48 hours where immobilization reached 20%.
- Mortality of control: none
- Abnormal responses: Decrease of spontaneous swimming was observed at 32 mg/L and above after 48 h exposure.
Results with reference substance (positive control):
EC50 (48h): 0.84 mg/L. The reference substance was tested in a 6-month interval.
Reported statistics and error estimates:
Immobilization rates (%) were calculated for each test group by dividing number of immobile daphnids by number of daphnids tested. A computer program (StatLight#08 regression analysis, version 2.00, Yukms Co., Ltd.) is used to perform the statistical analyses including Probit, Moving average or Binomial method.

Table 1: Immobilization rate of Daphnia magna

Immobilization [%]
Nominal concentration [mg/L] 24 hours 48 hours
0 0 0
10 0 0
18 0 0
32 0 0
56 0 0
100 0 20

The measured test concentrations were in the range of 100 - 101% of nominal.

Validity criteria fulfilled:
yes
Conclusions:
A 48-hour median effect concentration (EC50) of test item for Daphnía magna was >100 mg/L based on the mean measured concentration.
Executive summary:

A 48-hour EC50 of test item for Daphnía magna was determined from an acute immobilization test based on OECD 202. A static definitive test was conducted at nominal concentrations of 10, 18, 32, 56 and 100 mg/L with a spacing factor of 1.8 according to the results of a range finding test.

Abnormal swimming (decrease of spontaneous swimming) was observed at 32.3 mg/L and above after 48-hour exposure.

Immobilization rates at 10.0, 18.0, 32.3, 56.0 and 100 mg/L were 0, 0, 0, 0 and 20%, respectively, after 48-hour exposure.

Therefore, 48-hour median effect concentration (EC50) of test item for Daphnía magna was >100 mg/L based on the mean measured concentration.

Description of key information

The acute toxicity of test item for Daphnía magna was determined from an acute immobilization test based on OECD 202. The 48-hour median effect concentration (EC50) of test item for Daphnía magna was >100 mg/L based on the mean measured concentration.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
100 mg/L

Additional information