1,3-dihydro-5-methoxy-2H-benzimidazole-2-thione

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Experimental test result performed using standard OECD test guidelines

Justification for type of information:

Experimental test result performed using standard OECD test guidelines

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Principles of method if other than guideline:

Acute Toxicity Study of test material on Zebra Fish (Danio rerio) in a Static System (96 Hours)

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

The test substance was soluble in water. Therefore, the test solution was prepared by dissolving 62.5 mg, 125 mg, 250 mg, 500 mg& 1 g of the test substance in 10 liters of potable water (passed through reverse osmosis system) with continuous stirring for achieving test concentrations of 6.25 mg/L, 12.5 mg/L, 25 mg/L, 50 mg/l & 100 mg/L, respectively

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: Zebra Fish
- Strain: Danio rerio
- Source: Orange City Aquarium, Sitabuldi, Nagpur, MS (India)
- Age at study initiation (mean and range, SD):3-4 months
- Length at study initiation (length definition, mean, range and SD):average 2.28 cm
- Weight at study initiation (mean and range, SD):0.115 g (approx.)
- Method of breeding:
- Feeding during test
- Food type: Standard brand feed,
- Amount: No data available
- Frequency: once daily

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

pH:

7.0

Dissolved oxygen:

5.94 mg/L

Nominal and measured concentrations:

6.25 mg/L, 12.5 mg/L, 25 mg/L, 50 mg/l & 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: glass bowl aquaria of 12 inch each
- Material, size, headspace, fill volume: water capacity of 10 liters
- Aeration: Aeration in test vessels was provided 1 day before the start of experiment
- Renewal rate of test solution (frequency/flow rate):
- No. of organisms per vessel: 8 fishes
- No. of vessels per concentration (replicates):
- No. of vessels per control (replicates):
- No. of vessels per vehicle control (replicates):
- Biomass loading rate:

OTHER TEST CONDITIONS
- Adjustment of pH: 7.3
- Photoperiod: 12 hours light and 12-hour darkness

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 50 - < 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

Determination or calculation of the median lethal concentration (LC 50) and the symptoms of the nominal concentrations were done after 24, 48, 72 and 96 hours. LC0 (96 hours) (highest concentration at which no mortality was observed) = 50 mg/L
LC50 (96 hours) Experimental = > 50 mg/L
LC100 (96 hours) (lowest concentration at which 100% mortality was observed) = 100% mortality was not observed in any of the concentration

Sublethal observations / clinical signs:

Mortality and symptoms

Nominal conc. (mg/l)	Number of fish	Mortality (cumulated) after
		24h	48h	72h	96h
0 (control)	8	-	-	-	-
6.25	8	-	-	-	-
12.5	8	-	-	-	-
25	8	-	-	-	-
50	8	-	-	-	-
100	8	7	-	-	-

 

Visible Symptoms: Fishes were swimming slowly with showing any abnormal symptoms.

Nominal conc. (mg/l)	Number of fish	Symptoms after
		24h	48h	72h	96h
0 (control)	8	NS8	NS8	NS8	NS8
6.25	8	NS8	NS8	NS8	NS8
12.5	8	NS8	NS8	NS8	NS8
25	8	NS8	NS8	NS8	NS8
50	8	NS8	NS8	NS8	NS8
100	8	NS7	NS7	NS7	NS7

 

Explanation of symptoms:

A: apathy

N: narcotic-like state

C: swimming near water surface

D: swimming at the bottom of bowl

M: Slow movements compared to control

NS: No abnormal symptoms

Number behind symbol for symptom= number of affected fish

 

Conclusions:

Based on nominal concentrations, experimental median lethal Concentrations [LC-0 (96 h)] for test material on Zebra Fish were found to be > 50 mg/L. The LC50 was calulated to be 75 mg/L.

Executive summary:

Fish Acute Toxicity test according to OECD Guideline 203 was conducted for test material.The test substance was soluble in water. Therefore, the test solution was prepared by dissolving 62.5 mg, 125 mg, 250 mg, 500 mg& 1 g of the test substance in 10 liters of potable water (passed through reverse osmosis system) with continuous stirring for achieving test concentrations of 6.25 mg/L, 12.5 mg/L, 25 mg/L, 50 mg/l & 100 mg/L, respectively. The nominal concentration selected for the experiment were 6.25 mg/L, 12.5 mg/L, 25 mg/L, 50 mg/l & 100 mg/L and Zebra fish were exposed to these concentration for 96 hours. The fishes were slowly swimming without showing any abnormal symptoms. No mortalities were found in the control aquaria.The lethal concentrations LC0 was found to be 50 mg/L. And LC50 was calculated to be 75 mg/l.

Description of key information

Short term toxicity to fish:

Fish Acute Toxicity test according to OECD Guideline 203 was conducted for test material.The test substance was soluble in water. Therefore, the test solution was prepared by dissolving 62.5 mg, 125 mg, 250 mg, 500 mg& 1 g of the test substance in 10 liters of potable water (passed through reverse osmosis system) with continuous stirring for achieving test concentrations of 6.25 mg/L, 12.5 mg/L, 25 mg/L, 50 mg/l & 100 mg/L, respectively.The nominal concentration selected for the experiment were 6.25 mg/L, 12.5 mg/L, 25 mg/L, 50 mg/l & 100 mg/L and Zebra fish were exposed to these concentration for 96 hours. The fishes were slowly swimming without showing any abnormal symptoms. No mortalities were found in the control aquaria.The lethal concentrations LC0 was found to be 50 mg/L. And LC50 was calculated to be 75 mg/l.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

75 mg/L

Additional information

Short term toxicity to fish:

Fish Acute Toxicity test according to OECD Guideline 203 was conducted for test material.The test substance was soluble in water. Therefore, the test solution was prepared by dissolving 62.5 mg, 125 mg, 250 mg, 500 mg& 1 g of the test substance in 10 liters of potable water (passed through reverse osmosis system) with continuous stirring for achieving test concentrations of 6.25 mg/L, 12.5 mg/L, 25 mg/L, 50 mg/l & 100 mg/L, respectively.The nominal concentration selected for the experiment were 6.25 mg/L, 12.5 mg/L, 25 mg/L, 50 mg/l & 100 mg/L and Zebra fish were exposed to these concentration for 96 hours. The fishes were slowly swimming without showing any abnormal symptoms. No mortalities were found in the control aquaria.The lethal concentrations LC0 was found to be 50 mg/L. And LC50 was calculated to be 75 mg/l.