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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:
13-12-2016 to 15-12-2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Experimental test result performed using standard OECD test guidelines
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Principles of method if other than guideline:
Determination of short term toxicity to aquatic invertebrates using OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test).
GLP compliance:
no
Specific details on test material used for the study:
- Name of test material (as cited in study report): benzimidazole
- Molecular formula: C7 H6 N2
- Molecular weight: 118.1384 g/mol
- Smiles notation: c12c(nc[nH]1)cccc2
- Inchl : 1S/C7H6N2/c1-2-4-7-6(3-1)8-5-9-7/h1-5H,(H,8,9)
- Substance type: Organic
- Physical state: solid
Analytical monitoring:
yes
Vehicle:
yes
Details on test solutions:
The stock solution (120 mg/L) was prepared by dissolving powder in reconstituted water. The solution was kept in ultrasonic bath for 20 min. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with reconstituted test water.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water flea
- Strain: Straus
- Source: Own breeding at University of Chemistry and Technology, Prague
- Age at study initiation (mean and range, SD): The animals used for the test shall be less than 24 h old and should not be first brood progeny
- Feeding during test: No feeding
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Remarks on exposure duration:
± 1 hr
Test temperature:
20±1°C
pH:
Test: 8.0 (changed to 7.5 during test)
Control: 7.9 (changed to 7.6 during test)
Dissolved oxygen:
higher than 7.9 mg/L at the end of test
Nominal and measured concentrations:
0, 7.5, 15, 30, 60 and 120 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 50 ml glass vessel
- fill volume: 25 ml
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
Natural water (surface or ground water), reconstituted water or dechlorinated tap water are acceptable as culturing and dilution water if D. magna survives in it for the duration of the culturing, acclimation and testing without showing signs of stress. Waters in the range pH 6 to pH 9, with hardness between 140 mg/l and 275 mg/l (as CaCO3) are recommended.
As an example, the preparation of dilution water meeting the requirements is described below.
Dissolve known quantities of reagents in water. The dilution water prepared shall have a pH of 7.8 ± 0.5, a hardness of (225 ± 50) mg/l (expressed as CaCO3), a molar Ca + Mg ratio close to 4 + 1 and a dissolved oxygen concentration above 7 mg/l.

Prepare the solutions specified below:
- Calcium chloride solution: Dissolve 117.6 g of calcium chloride dihydrate (CaCl2.2H2O) in water (4.2) and make up to 1 l with water (4.2).
- Magnesium sulfate solution: Dissolve 49.3 g of magnesium sulfate heptahydrate (MgSO4.7H2O) in water (4.2) and make up to 1 l with water (4.2).
- Sodium bicarbonate solution: Dissolve 25.9 g of sodium bicarbonate (NaHCO3) in water (4.2) and make up to 1 l with water (4.2).
- Potassium chloride solution: Dissolve 2.3 g of potassium chloride (KCI) in water (4.2) and make up to 1 l with water (4.2).

Mixing
Mix 2.5 ml of each of the four solutions and make up to 1 l with water.
The dilution water shall be aerated until the dissolved oxygen concentration has reached saturation and the pH has stabilized. If necessary, adjust the pH to 7.8 ± 0.5 by adding sodium hydroxide (NaOH) solution or hydrochloric acid (HCI). The dilution water prepared in this way shall not be further aerated before use.

- Sodium hydroxide solution, e.g. [NaOH] : 1 mol/l.
- Hydrochloric acid, e.g. [HCl] : 1 mol/l.

Reference substance:
Dissolve 600 mg of potassium dichromate (K2Cr2O7) in water and make up to 1 l with water (4.2).

OTHER TEST CONDITIONS
- Adjustment of pH: no adjustment done
- Photoperiod: No - Darkness
- Light intensity:

CALCULATION:
EC50 was calculated using non linear regression by the software Prism 4.0
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (K2Cr2O7)
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
55.5 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL: 43.5-70.8
Results with reference substance (positive control):
- Results with reference substance valid
- EC50: 0.79 mg/L (24 hours)
Reported statistics and error estimates:
EC 50 was calculated using non-linear regression by the software prism 4.0
Validity criteria fulfilled:
yes
Conclusions:
Experimental study for inhibition of mobility of daphnids was carried out with the benzimidazole according to OECD Guideline 202. The median effective concentration (EC50) for the test substance benzimidazole, in Daphnia magna was determined to be 55.5 mg/L on the basis of mobiity inhibition effects in a 48 hour study.
Executive summary:

Experimental study for inhibition of the mobility of daphnids was carried out with the benzimidazole according to OECD Guideline 202. The animals used for the test shall be less than 24 h old and should not be of first brood progeny. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with reconstituted test water. The test substance was tested at the concentrations 0, 7.5, 15, 30, 60 and 120 mg/L. The test was performed under static conditions in a static fresh water system at 20±1°C temperature. Effects on immobilisation were observed for 48 hours. EC50 was calculated using non linear regression by the software Prism 4.0. After the experiment, the median effective concentration (EC50) for the test substance, benzimidazole, in Daphnia magna was determined to be 55.5 mg/L on the basis of immobilisation effects. Based on the EC50 value chemical consider to be toxic and classified as aquatic chronic 3 as per the CLP classification criteria. But as the chemical was readily biodegradable in water, thus it not exist for longer period of time. Thus on that basis chemical consider to be nontoxic and not classified as per the CLP classification criteria.

Description of key information

Experimental study for inhibition of the mobility of daphnids was carried out with the benzimidazole according to OECD Guideline 202. The animals used for the test shall be less than 24 h old and should not be of first brood progeny. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with reconstituted test water. The test substance was tested at the concentrations 0, 7.5, 15, 30, 60 and 120 mg/L. The test was performed under static conditions in a static fresh water system at 20±1°C temperature. Effects on immobilisation were observed for 48 hours. EC50 was calculated using non linear regression by the software Prism 4.0. After the experiment, the median effective concentration (EC50) for the test substance, benzimidazole, in Daphnia magna was determined to be 55.5 mg/L on the basis of immobilisation effects. Based on the EC50 value chemical consider to be toxic and classified as aquatic chronic 3 as per the CLP classification criteria. But as the chemical was readily biodegradable in water, thus it not exist for longer period of time. Thus on that basis chemical consider to be nontoxic and not classified as per the CLP classification criteria.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
55.5 mg/L

Additional information

Experimental study for inhibition of the mobility of daphnids was carried out with the benzimidazole according to OECD Guideline 202. The animals used for the test shall be less than 24 h old and should not be of first brood progeny. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with reconstituted test water. The test substance was tested at the concentrations 0, 7.5, 15, 30, 60 and 120 mg/L. The test was performed under static conditions in a static fresh water system at 20±1°C temperature. Effects on immobilisation were observed for 48 hours. EC50 was calculated using non linear regression by the software Prism 4.0. After the experiment, the median effective concentration (EC50) for the test substance, benzimidazole, in Daphnia magna was determined to be 55.5 mg/L on the basis of immobilisation effects. Based on the EC50 value chemical consider to be toxic and classified as aquatic chronic 3 as per the CLP classification criteria. But as the chemical was readily biodegradable in water, thus it not exist for longer period of time. Thus on that basis chemical consider to be nontoxic and not classified as per the CLP classification criteria.