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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:
1993
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Reference:
Composition 1
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
chemical analyses were not performed
GLP compliance:
no
Test material information:
Composition 1
Specific details on test material used for the study:
- Lot/batch No.: RCD/GU 2892
- Physical state: Solid
- Analytical purity: 91.6%
- Sample code: ECO 42
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
0.1 g/L stock solution was prepared by by adding 0.1 g to approximately 80 mL deionized water. The mixture was stirred for 30 minutes. Thereafter, deionised water was added up to a final volume of 1L. A clear homogeneous solution was obtained.
Test concentrations were prepared by dilution of the stock solution in Dutch Standard Water: control (0), 0.01, 0.018, 0.032, 0.058 and 0.105 mg/L nominal.
Test organisms (species):
Daphnia magna
Details on test organisms:
The test was performed with Daphnia magna (water fleas), of which a continuous culture is maintained at the Akzo Research Laboratories, Amhem. The animals used in the test were less than 24 hours old at the beginning of the test and were obtained from parent animals having an age of 24 weeks.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
approximately 12°dH
Test temperature:
19.9 - 20.4°C
pH:
8.1
Dissolved oxygen:
8.8 mg/L or 97%
Salinity:
Fresh water
Nominal and measured concentrations:
0.01, 0.0 18, 0.032, 0.058 and 0.105 mg/L nominal
Details on test conditions:
As test vessels were used 400 mL glass beakers containing 250 mL of test medium, which were covered with a glass plate. Each beaker contained 5 animals. In the definitive test per test concentration and control 20 animals were tested, divided into four batches of 5 animals each. The diluting water used for the preparation of the test concentrations was a synthetic water, Dutch Standard Water, having a pH of approximately 8.2 and a hardness of approximately 12"dH, containing per litre of deionized water:
100 mg of NaHC03
20 mg of KHCO,
200 mg of CaCI2.2H2O
180 mg of MgSO4.7H2O
The delonised water used had a conductivity of less than 5 p S/cm, a TOCcontent of less than 2 mg/L and contained no more than 0.01 mg copper/L.
The test was carried out in a temperature controlled room.
During the test the air temperature was continuously registered.
The light regime was 16 hours of ambient light per day, supplied by fluorescent tubes.
Measurements of pH and the oxygen concentrations were carried out at the beginning and at the end of the test in one random beaker per test concentration and control.
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.037 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
mobility
Remarks on result:
other: 95% CL 0.03 - 0.04 mg/L
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
0.016 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
mobility
Details on results:
At 0.01 mg/L, which was the lowest concentration tested, one animal was immobile after 48h. This is in the range of immobilization also allowed by the quality criteria for the control group. At the next higher concentration (0.018 mg/L) all animals survived and therefore, the NOEC after 48h amounts to 0.018 mg/L.
The lowest concentration producing 100% immobilization within 48h was 0.058 mg/L. The EC50 (48h) was calculated to be 0.04 mg/L with 95% confidence limits of 0.03 and 0.04 mg/L.
Reported statistics and error estimates:
The LC50, was calculated with a programme (Akzo programme SKBT, version 1.0). using both the binomial test method and the trimmed Spearman-Karber method.

Table 1. Mobility results

Immobility in the definitive test  
Concentration  Number of mobile animals
of test substance Test duration (h)  
mg/L   0 24 48
Control
0.01 1 5 5 5
2 5 5 5
3 5 5 5
4 5 5 5
Total 20 20 20
0.018 1 5 5 5
2 5 5 5
3 5 5 5
4 5 5 5
Total 20 20 20
0.032 1 5 5 5
2 5 5 5
3 5 4 2
4 5 5 2
total 20 19 14
0.058 1 5 0 0
2 5 1 0
3 5 1 0
4 5 1 0
total 20 3 0
0.105 1 5 0 0
2 5 0 0
3 5 0 0
4 5 0 0
  total 20 0 0
Conclusions:
Under the study conditions, the 48h EC50 and NOEC of the test substance was calculated to be 0.04 mg/L (equivalent to 0.037 mg a.i./L) and 0.018 mg/L (equivalent to 0.016 mg a.i./L), respectively.
Executive summary:

A study was conducted to determine the short-term toxicity of the test substance (91.6% active ingredient) to aquatic invertebrates according to OECD Guideline 202. Twenty Daphnia magna per group were exposed under static conditions to nominal concentrations of 0.01, 0.018, 0.032, 0.058 and 0.105 mg/L. Immobility was recoded at regular intervals. No analytical dose verification was conducted. At 0.01 mg/L, one animal was immobile after 48 h. This was in the range allowed by the quality criteria for the control group. At the next higher concentration of 0.018 mg/L, all animals survived. The 48 h NOEC was therefore established at 0.018 mg/L. The lowest concentration producing 100% immobilization was 0.058 mg/L. Under the study conditions, the 48 h EC50 was calculated to be 0.04 mg/L (equivalent to 0.037 mg a.i./L), with 95% confidence limits of 0.03 and 0.04 mg/L (Mark, 1993).

Description of key information

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.037 mg/L

Additional information

A study was conducted to determine the short-term toxicity of the test substance (91.6% active ingredient) to aquatic invertebrates according to OECD Guideline 202. Twenty Daphnia magna per group were exposed under static conditions to nominal concentrations of 0.01, 0.018, 0.032, 0.058 and 0.105 mg/L. Immobility was recoded at regular intervals. No analytical dose verification was conducted. At 0.01 mg/L, one animal was immobile after 48 h. This was in the range allowed by the quality criteria for the control group. At the next higher concentration of 0.018 mg/L, all animals survived. The 48 h NOEC was therefore established at 0.018 mg/L. The lowest concentration producing 100% immobilization was 0.058 mg/L. Under the study conditions, the 48 h EC50 was calculated to be 0.04 mg/L (equivalent to 0.037 mg a.i./L), with 95% confidence limits of 0.03 and 0.04 mg/L (Mark, 1993).