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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 July 01, 2009 to July 09, 2009
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)
Deviations:
yes
Remarks:
see 'Principles of method if other than guideline'
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Deviations:
no
Principles of method if other than guideline:
Periodic analyses of well water for potential contaminants were not preformed according to Good Laboratory Practice Standards, but were performed using a certified laboratory and standard U.S. EPA analytical methods.
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Mean measured test concentrations were determined from samples of test water collected from the batches of test solutions prepared for each treatment and control group at the beginning of the test, and from each replicate per treatment and control group at test termination.
Vehicle:
no
Details on test solutions:
Daphnids were exposed to a geometric series of five test concentrations and a negative (UV sterilized well water) control. Two replicate test chambers were maintained in each treatment and control group, with 10 daphnids in each test chamber, for a total of 20 daphnids per test concentration. Nominal test concentrations were selected based upon the results of an exploratory range finding toxicity test. Nominal test substance concentrations selected for the definitive study were: 3.1, 6.3, 13, 25 and 50 mgL.
Test organisms (species):
Daphnia magna
Details on test organisms:
Species: Cladoceran (Daphnia magna)
Age: < 24 hr at test initiation
Source: Wildlife International, Ltd. Maryland, USA
Feeding during test: Not fed during the exposure period
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
136 mg CaCO3/L (at test initiation)
Test temperature:
20.2 – 20.6 st. C (Daily measurements)
20.0 – 20.5 st. C (Continuous Measurements)
pH:
8.5 – 8.9
Dissolved oxygen:
7.7 – 8.8 mg/L (≥86% of air saturation)
Conductivity:
356 μS/cm (at test initiation)
Nominal and measured concentrations:
Nominal: negative control; 3.1 mg/L; 6.3 mg/L; 13 mg/L; 25 mg/L; 50 mg/L
Mean Measured: < LOQ; 2.9 mg/L; 6.0 mg/L; 14 mg/L; 24 mg/L; 48 mg/L
Details on test conditions:
Light intensity: 451 lux (at test initiation)
Photoperiod: 16-hour light: 8 hour darkness with 30 min. transition period
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
15 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: Confidence intervals
Remarks:
12 to 17 mg/L
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
6 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
After 48-hours of exposure, all daphnids in the 2.9 and 6.0 mg MON 51803/L treatment groups appeared normal, with no overt signs of toxicity through out the test. Immobility at 48-hours in the 14, 24 and 48 mg test substance/L treatment groups was 40, 95 and 100%, respectively, with lethargy noted among surviving daphnids in the 14 and 24 mg test substance/L treatment group.
Reported statistics and error estimates:
The immobility data were analyzed using the computer program of C. E. Stephan. The program was designed to calculate the EC50 value and the 95% confidence interval by probit analysis, the moving average method, and binomial probability with nonlinear interpolation (8, 9, 10). In this study, the probit method was used to calculate both the 24 and 48-hour EC50 values. The no-immobility concentration and NOEC were determined by visual interpretation of the immobility and observation data.
Validity criteria fulfilled:
yes
Conclusions:
Under the study conditions, the 48 h EC50 value was 15 mg/L, with a 95% confidence interval of 12 to 17 mg/L. The slope of the concentration-response curve was 8.202. The no-immobility concentration and the NOEC were both 6.0 mg/L.
Executive summary:

A study was conducted to determine the toxicity of the test substance to Daphnia magna according to OECD Guideline 202, EU Method C.2 and EPA OPPTS Method 850.1010, in compliance with GLP. Daphnids were exposed to a geometric series of five test concentrations and a negative (UV sterilized well water) control. Two replicate test chambers were maintained in each treatment and control group, with 10 daphnids in each test chamber, for a total of 20 daphnids per test concentration. Nominal concentrations were selected based upon the results of an exploratory range finding toxicity study. Nominal test substance concentrations selected for the definitive study were: 3.1, 6.3, 13, 25 and 50 mgL, which corresponded to 2.9; 6.0; 14; 24 and 48 mg/L mean measured values. Observations of immobility and other clinical signs were made approximately 3, 24 and 48 h after test initiation. Cumulative percent immobility observed in the treatment groups was used to determine EC50 values at 24 and 48 h. The no- immobility concentration and the NOEC were estimated by visual interpretation of the immobility and observation data. Under the study conditions, the 48 h EC50 was 15 mg/L, with a 95% confidence interval of 12 to 17 mg/L. The slope of the concentration-response curve was 8.202. The no-immobility concentration and the NOEC were both 6.0 mg/L (Minderhout, 2010).

Description of key information

A study was conducted to determine the toxicity of the test substance to Daphnia magna according to OECD Guideline 202, EU Method C.2 and EPA OPPTS Method 850.1010, in compliance with GLP. Daphnids were exposed to a geometric series of five test concentrations and a negative (UV sterilized well water) control. Two replicate test chambers were maintained in each treatment and control group, with 10 daphnids in each test chamber, for a total of 20 daphnids per test concentration. Nominal concentrations were selected based upon the results of an exploratory range finding toxicity study. Nominal test substance concentrations selected for the definitive study were: 3.1, 6.3, 13, 25 and 50 mgL, which corresponded to 2.9; 6.0; 14; 24 and 48 mg/L mean measured values. Observations of immobility and other clinical signs were made approximately 3, 24 and 48 h after test initiation. Cumulative percent immobility observed in the treatment groups was used to determine EC50 values at 24 and 48 h. The no- immobility concentration and the NOEC were estimated by visual interpretation of the immobility and observation data. Under the study conditions, the 48 h EC50 was 15 mg/L, with a 95% confidence interval of 12 to 17 mg/L. The slope of the concentration-response curve was 8.202. The no-immobility concentration and the NOEC were both 6.0 mg/L (Minderhout, 2010).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
15 mg/L

Additional information