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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
in 1988
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Reason / purpose:
reference to same study
Related information:
Composition 1
Reference:
Composition 0
Qualifier:
according to
Guideline:
other: The test was conducted in line with the provisional procedure "Extended toxicity test using Daphnia magna" proposed by the Federal Environmental Agency, Germany.
Version / remarks:
1984
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
GLP compliance:
no
Test material information:
Composition 1
Analytical monitoring:
yes
Details on sampling:
- Concentrations: all test concentrations, blank preparations (without test organisms or feed)
- Sampling method: samples were taken twice from selected concentration levels of the test series during the test period and analysed chemically. The first sampling was on one of the transfer days before day 7 (period when no offspring appeared). The second sampling was between day 16 and 21. The concentrations were determined in the freshly prepared solutions and in old test solutions after 48 h or 72 h, respectively.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: test substance in the stock solution was fully dissolved quantitatively and optically by stirring with magnets. Then the test solutions were prprepared by diluting the stock solution in 1:2 dilution steps with standardised artificial medium (DIN 38412).
- Controls: yes
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no, test substance optically dissolved
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Strain/clone: IRCHA
- Source: own (maintained since 1978)
- Age of parental stock (mean and range, SD): 24 h-old
- Feeding during test
- Food type: Tetramin (fish feed) and activated sludge
- Amount: 15 - 20 mg COD/L
- Frequency: daily

ACCLIMATION
- Acclimation period: 24 h
- Type and amount of food: green algae Scenedesmus sp., 2 mL of a 9 g dry algae/L suspension
- Feeding frequency: daily
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Hardness:
2.5 mmol/L (Ca/Mg in dilution water)
Test temperature:
25 +- 1°C
pH:
7 - 8.0
Dissolved oxygen:
58 - 69%
Nominal and measured concentrations:
Nominal: 0 (control), 0.8, 1.6, 3.1, 6.3, 12.5, 25, 50 mg/L
Measured: 1.3 mg/L as minimum measured concentration is equivalent to 6.3 mg/L nominal concentration
Details on test conditions:
TEST SYSTEM
- Test vessel: wide-neck bottles
- Type: closed
- Material, size, headspace, fill volume: glass, ground-glass stoppers
- Aeration: no
- Renewal rate of test solution (frequency/flow rate): 3 times/week
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 1 animal/50 mL

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: 90% deionized water, 10% tap water
- Na/K ratio: 10:1
- Culture medium different from test medium: yes, culture medium: aerated tap water, test medium: artificial medium according to DIN 38412
- Intervals of water quality measurement: at each transfer day

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 9 h light : 15 h dark
- Light intensity: fluorescent lamps with 40/25 W

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : parent mortality, reproduction, appearance of first offspring

RANGE-FINDING STUDY
- Test concentrations: same test concentrations, performed for 3 days
- Results used to determine the conditions for the definitive study: yes, dilution steps have been derived from a preliminary 24 h acute toxicity test (24 h-EC50: 286 mg/L).
Reference substance (positive control):
yes
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
6.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: The most sensitive endpoint was parental mortality beside the reproduction and the number of offspring
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
1.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: The most sensitive endpoint was parental mortality beside the reproduction and the number of offspring
Details on results:
- Mortality of parent animals: 9.1% (control), most sensitive parameter
- No. of offspring produced per day per female: 68.0 (control, SD: 10.6%, coefficient of variation: 15.6%)
- Time to first brood release: 7 days (control)
- Effect concentrations exceeding solubility of substance in test medium: no, optically clear test solutions
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Relevant effect levels: The 24 h-EC50 was determined at 0.35 mg/L which indicates a normal toxicity response of the test organisms
- Other: 73 organic and inorganic substances were tested. No explicit positive control was used. Potassium dichromate was tested in a 24 h acute toxicity test which is the positive control in acute toxicity tests (OECD 202).

Table 1: Long-term toxicity results with Ethyl propionate

Chronic toxicity test with D. magna

21 d - NOEC

(nominal)

21 d - NOEC

(minimum measured)

6.3 mg/L

1.3 mg/L

The results are based on 7 test concentrations each with 4 replicates. Only the most sensitive endpoint was stated for chronic toxicity (parental animal mortality). The nominal concentrations were analytically verified.

Validity criteria fulfilled:
yes
Conclusions:
The long-term toxicity of the test substance on Daphnia magna was determined according to the provisional procedure "Extended toxicity test using Daphnia magna" (1984) proposed by the Federal Environmental Agency, Germany. The 21 d-NOEC value for parental mortality as the most sensitive parameter obtained for the test substance was 6.3 mg/L (nominal) and 1.3 mg/L (minimum measured). For further assessments the NOEC value of 1.3 mg/L is taken as key result because the deviation between measured and nominal concentration was more than 20%.

Description of key information

21 d - NOEC = 1.3 mg/L (minimum measured)

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
1.3 mg/L

Additional information

The long-term toxicity of the test substance on Daphnia magna was determined according to the provisional procedure "Extended toxicity test using Daphnia magna" (1984) proposed by the Federal Environmental Agency, Germany. Individuals were exposed to the test substance at 0.8, 1.6, 3.1, 6.3, 12.5, 25, 50 mg/L, which were analytically verified, for 21 days. No further details were reported about the analytical methods used. The NOEC value for parental mortality as the most sensitive parameter obtained for the test substance was 6.3 mg/L (nominal) and 1.3 mg/L (minimum measured). For further assessments the NOEC value of 1.3 mg/L is taken as key reult because the deviation between measured and nominal concentration was more than 20%.