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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:
2006-07-10 - 2006-07-12
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: ‘Testing Methods for New Chemical Substances’ of Pharmaceutical and Food Safety Bureau (PFSB), Ministry of Health, Labour and Welfare
Deviations:
not specified
Qualifier:
according to
Guideline:
other: Environmental Policy Bureau-Ministry of the Environment (November 21, 2003 No. 1121002; November 13, 2003, No. 2; Manufacturing Industries Bureau, Ministry of Economy, Trade and Industry No. 031121002)
Deviations:
not specified
GLP compliance:
yes
Remarks:
"Standard Concerning Testing Facility Relating to New Chemical Substances" (November 21, 2003 No. 1121003; PFSB, Ministry of Health, Labour and Welfare November 17, 2003, No. 3; Environmental Policy Bureau, Ministry of the Environment No. 031121004)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 10, 13, 18, 24 and 32 mg/L and a control
- Sampling method: At the beginning of exposure (test start = 0h), 13 mL were taken from each prepared solution, and after 48 hours (test end) equal amounts of test solutions were collected from the middle layer of each test container and analyzed by HPLC method.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Defined amounts of the test material were disolved in test water (Elendt M4) as homogeneously as possible, to obtain the test solutions of the desired test concentrations.
- Controls: Elendt M4 test medium only.
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): No. Visual check and filtration by 22 μm membrane filter confirmed > 400 mg/L solubility by measuring the concentration of the test substance by HPLC.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Source: National Environmental Institute of the Ministry of the Environment of Japan (receipt 1997-02-05)
- Management after receipt: subculture rearing (maximum breeding period: 4 weeks; water changing frequency: at least twice a week)
- Feeding during test: No.
- Age of test organism at test start: Juveniles less than 24-hour-old.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
at test start: 253 - 258 mg CaCO3/L
at test end (48 h): 242 - 252 mg CaCO3/L
Test temperature:
at test start (0 h): 20.5 °C
at test end (48 h): 20.5 °C
pH:
at test start (0 h): 7.9
at test end (48 h): 7.9
Dissolved oxygen:
at test start (0 h): 8.5 mg/L
at test end (48 h): 8.4 - 8.5 mg/L
Nominal and measured concentrations:
Nominal concentrations: 10, 13, 18, 24 and 32 mg/L (spacing factor 1.3) and a control
Geometric mean measured concentrations: 9.65, 12.5, 17.2, 23.3 and 30.8 mg/L and a control
Details on test conditions:
TEST SYSTEM
- Material, size, headspace, fill volume: 100 mL/vessel
- Aeration: no
- No. of organisms per vessel: 5 daphnia/vessel
- No. of vessels per concentration (replicates): 4 vessels/test group
- No. of vessels per control (replicates): 4 vessels/control

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4 (see "Any other information on materials and methods incl. tables")
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16-hour light/8-hour dark
- Light intensity: Indoor light

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : The number of swimming inhibition of Daphnia was observed 24 and 48 hours after the initiation of exposure. After gently moving the test container, if swimming did not swim during the observation period of 15 seconds, it was considered to be swimming-inhibited.

VEHICLE CONTROL PERFORMED: no

RANGE-FINDING STUDY
- Results used to determine the conditions for the definitive study: Within a preliminary test an 48h-EC0 of 10 mg/L and an 48h-EC100 of 32 mg/L was determined. Accordingly, the test concentrations were set to 10, 13, 18, 24 and 32 mg/L (spacing factor 1.3).
Reference substance (positive control):
yes
Remarks:
potassium dichromate, guaranteed reagent
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
9.7 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
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
Duration:
48 h
Dose descriptor:
EC100
Effect conc.:
23 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC0
Effect conc.:
13 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
18 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC100
Effect conc.:
23 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Other biological observations: Environmental factors that seemed to have influenced the reliability of the test results were not recognized.
- Mortality of control: The swimming inhibition rate in the control group exposed for 48 hours was 0%, and the daphnia floated on the water surface was 0%, satisfying the test establishment condition.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: The slight change in the concentration of the test substance was considered to be mainly due to decomposition by light.
- Effect concentrations exceeding solubility of substance in test medium: No. Visual check and filtration by 22 μm membrane filter confirmed >400 mg/L solubility by measuring the concentration of the test substance by HPLC.
Results with reference substance (positive control):
- Results with reference substance valid? Yes.
- Relevant effect levels: 48h-EC50 = 0.75 mg/L (the average EC50 value after October 1999 in the test facility was 0.89 mg/L, S.D.= 0.22 mg/L, n = 16 (M4 water)).
Reported statistics and error estimates:
EC50 was calculated by the Probit method.
Validity criteria fulfilled:
yes
Conclusions:
The study was performed under GLP according to relevant Japanese test guidelines, without deviations which may have impact on the validity of the study. Thus, the results were obtained via a scientifically reasonable method. Hence, there is no doubt that the obtained results are not reliable. According to the reported 48h-EC50 value of 15 mg/L the test substance possesses a certain toxic potential towards aquatic invertebrates.
Executive summary:

In the present study the acute toxicity of Benzalaceton towards aquatic invertebrates was investigated according to relevant Japanese test guidelines (‘ ‘Testing Methods for New Chemical Substances’ of Pharmaceutical and Food Safety Bureau (PFSB), Ministry of Health, Labour and Welfare, as well as Environmental Policy Bureau-Ministry of the Environment (November 21, 2003 No. 1121002; November 13, 2003, No. 2; Manufacturing Industries Bureau, Ministry of Economy, Trade and Industry No. 031121002)), without deviations which may have impact on the validity of the study. No GLP certificate is included, however, the study was performed under GLP compliance.

Daphnia magna was used as test organisms. 20 animals per test group were exposed to test substance concentrations of 10, 13, 18, 24 and 32 mg/L for 48 hours in a static test. A control was included and the reference substance potassium dichromate was tested at regular intervals. Under the conditions used for the test, the following effect concentrations were determined based on immobilisation:

48h-EC50 = 15 mg/L

48h-EC0 = 9.7 mg/L

48h-EC100 = 23 mg/L

As a conclusion of the analytical part of this study, a slight change in the concentration of the test substance in the test solutions at test start and test end was observed, which was considered to be mainly due to decomposition by light. Therefore, the geometric mean value was calculated using the measured values at the beginning and at the end of exposure. The biological results were based on the geometric mean measured concentrations of the test substance accordingly.

Description of key information

Japanese guideline study (GLP), Daphnia magna: EC50 (48h) = 15 mg/L (geometric mean)

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
15 mg/L

Additional information

The acute toxicity of Benzalaceton towards aquatic invertebrates was investigated according to relevant Japanese test guidelines (‘Testing Methods for New Chemical Substances’ of Pharmaceutical and Food Safety Bureau (PFSB), Ministry of Health, Labour and Welfare, as well as Environmental Policy Bureau-Ministry of the Environment (November 21, 2003 No. 1121002; November 13, 2003, No. 2; Manufacturing Industries Bureau, Ministry of Economy, Trade and Industry No. 031121002)), without deviations which may have impact on the validity of the study (Kureha, 2006). No GLP certificate is included, however, the study was performed under GLP compliance. Daphnia magna was used as test organisms. 20 animals per test group were exposed to test substance concentrations of 10, 13, 18, 24 and 32 mg/L for 48 hours in a static test. A control was included and the reference substance potassium dichromate was tested at regular intervals. Under the conditions used for the test, a 48h-EC0 of 9.7 mg/L, a 48h-EC50 of 15 mg/L and a 48h-EC100 of 23 mg/L were determined based on immobilisation. As a conclusion of the analytical part of this study, a slight change in the concentration of the test substance in the test solutions at test start and test end was observed, which was considered to be mainly due to decomposition by light. Therefore, the geometric mean value was calculated using the measured values at the beginning and at the end of exposure. The biological results were based on the geometric mean measured concentrations of the test substance accordingly.

As supporting information, the acute toxicity of the test substance to daphnids was predicted by the computer program ECOSAR v1.11 (EPIWIN v4.1) by US EPA. An extensive set of structure – activity relationships (SARs) is utilized by the computer program, to predict the acute and chronic toxicity for three trophic levels for aquatic species.The mode of toxic action for most neutral organic chemicals is narcosis, and many chemical classes present toxicity to organisms via narcosis (i.e. ethers, alcohols, ketones). However, some organic chemical classes have been identified as having a more specific mode of toxicity. These are typically organics that are reactive and ionizable and that exhibit excess toxicity in addition to narcosis (i.e. acrylates, epoxides, anilines).The query substance belongs to the specific EOSAR class of Vinyl/Allyl Ketones. However, the SAR for neutral organics is more reliable due to the larger training set. In addition, the result with the neutral organic SAR is lower than with the specific Vinyl/Allyl Ketones SAR. This indicates that narcosis induced by the neutral organic is the primary toxic effect of benzalacetone. For daphnids an LC50 value of 63.32 mg/L is predicted with the neutral organic SAR.