2,3,3-trimethyl-3H-indole-5-carboxylic acid

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:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: Letale Wirkung beim Zebra baerbling Brachydanio rerio (LC 0, LC 50, LC 100; 48 - 96 h), UBA test protocol Mai 1984

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

no

Analytical monitoring:

no

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

Name: Zebra fish (Danio rerio)
Source: West Aquarium GmbH (Germany)
Date of birth: not reported
Date supplied: not reported
Temperature: 20 - 24 °C
Dissolved oxygen: > 5 mg/L
Feeding: Commercial fish food, daily. Feeding discontinued 24 h prior to test start.
Mortalities during acclimatisation period: < 5 %
Medication: none

Holding and dilution water
Reconstituted water prepared according to the recommendations of ISO (hardness: 13° dH, acidity: 0.1 +/- 0.02 mmol/l, Ca / Mg: 4:1, pH: 8.0 – 8.4, oxygen: >= 90 % of saturation). This freshly prepared standard dilution water was used for the maintenance of the test animals under flow-through conditions and for the preparation of stock and test solutions of the test item.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

13 °dH

Test temperature:

19.5 - 21.5 °C

pH:

4.2 - 7.1

Dissolved oxygen:

8.0 - 9.6

Nominal and measured concentrations:

nominal concentrations: 12.5, 17.7, 25.0, 35.4, 50.0, 70.7, 100.0, 2000 mg/L

Details on test conditions:

Test vessels: glass aquaria holding 5 L of test media covered by glass plates
Experimental design: 8 test concentrations, 10 fish per test concentration, no feeding during the exposure period
Method of initiation: fish were placed in prepared media
Photoperiod: 16 h light: 8 h dark
Temperature: 19.5 to 21.5 °C
Aeration: gentle aeration via narrow glass tubes
Method of administration: direct weighing
Medium renewal: none
Criteria of effects: absence of response to physical stimulation; in addition to observations on mortality at 2, 24, 48, 72 and 96 hours, type and incidence of sub lethal effects compared with control fish were observed

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

70.7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

24 h

Dose descriptor:

LC100

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: due to decreased pH

Details on results:

The mortality was 100 % at concentrations > 100 mg/L after 24 h. According to the test guidelines acute fish tests should be carried out without adjustment of pH and OECD guideline describes water with a pH 6.0 to 8.5 is preferable for the test. However, the pH decreased in the test from 7.2 to 4.2 during 24 h due to intrinsic property of the test material. Thus it is most likely that the low pH-value is the reason for the mortality and not the toxicity of the substance. Therefore no LC50 could be determined and just a LC0 of >=70.7 mg/L is derived.

Sublethal observations / clinical signs:

concentration of test item, number of fish: normal swimming behaviour/abnormal swimming behaviour/dead and pH-values

	24 h (pH)	48 h (pH)	72 h (pH)	96 h (pH)
12.5 mg/L	10/0/0 (5.5)	10/0/0 (6.0)	10/0/0 (6.1)	10/0/0 (6.5)
17.7 mg/L	10/0/0 (6.3)	10/0/0 (6.4)	10/0/0 (6.5)	10/0/0 (6.5)
25 mg/L	10/0/0 (6.5)	10/0/0 (6.4)	10/0/0 (6.5)	10/0/0 (6.5)
35.4 mg/L	10/0/0 (6.3)	10/0/0 (6.5)	10/0/0 (6.4)	10/0/0 (6.5)
50 mg/L	10/0/0 (6.2)	10/0/0 (5.9)	10/0/0 (5.9)	10/0/0 (5.9)
70.7 mg/L	10/0/0 (6.6)	10/0/0 (5.9)	10/0/0 (5.8)	10/0/0 (5.8)
100 mg/L	10/0/10 (4.6)	-	-	-
2000 mg/L	10/0/10 (4.2)	-	-	-

Conclusions:

For 2,3,3-trimethyl-3H-indole-5-carboxylic acid the mortality of fish at concentrations > 100 mg/L is probably due to decreased ph-values and not toxicity. Thus no LC50 could be determined and just a LC0 of >=70.7 mg/L is derived.

Executive summary:

The study was conducted according to UBA test protocol: Letale Wirkung beim Zebrabaerbling Brachydanio rerio, (LC 0, LC 50, LC 100; 48 – 96H) Mai 1984, which is comparable to the OECD Guideline for Testing of Chemicals No. 203 'Fish, Acute Toxicity Test' and assesses the acute toxic effects (mortality) of various concentrations of 2,3,3 -trimethyl-3H-indole-5 -carboxylic acid to a freshwater fish species.

The test was conducted for 96 h as a static test and 10 fish (Brachydanio rerio) were tested per concentration. The fishs were exposed to 8 concentrations (12.5, 17.7, 25.0, 35.4, 50.0, 70.7, 100.0, 2000 mg/L (nominal)) of 2,3,3-trimethyl-3H-indole-5-carboxylic acid. During the test a temperature range of 20 - 22 °C was maintained in the test vessels, with a maximum temperature fluctuation of +/- 1 °C in the test. The temperature, the pH and the oxygen values were measured at the beginning of the test and every 24 hours thereafter. Mortalities and abnormal behaviour were recorded at 24-hour intervals.

The mortality was 100 % at concentrations > 100 mg/L after 24 h. However, this effect could also be ascribed to the decrease of the pH-value after 24 h (4.6 at 100 mg/L and 4.2 at 2000 mg/L) due to intrinsic properties of 2,3,3-trimethyl-3H-indole-5-carboxylic acid as Brachydanio rerio should be kept at pH-values between 6.0 and 8.0 according to the test guideline. At a concentration of 70.7 mg/L the pH-value is 6.6 after 24 h and 5.8 after 96 h. No mortality is observed at this concentration. Thus it is most likely that the low pH-value is the reason for mortality at 100 mg/L and not the toxicity of the substance. Therefore no LC50 could be determined and just a LC0 of >=70.7 mg/L is derived.

Description of key information

A study was conducted according to UBA test protocol "Letale Wirkung beim Zebrabaerbling Brachydanio rerio, (LC 0, LC 50, LC 100; 48 – 96H) Mai 1984", which is comparable to the OECD Guideline for Testing of Chemicals No. 203 'Fish, Acute Toxicity Test'. The test was conducted for 96 h as a static test and 10 fish (Brachydanio rerio) were tested per concentration. The fishs were exposed to 8 concentrations (12.5, 17.7, 25.0, 35.4, 50.0, 70.7, 100.0, 2000 mg/L (nominal)) of 2,3,3-trimethyl-3H-indole-5-carboxylic acid.

The mortality was 100 % at concentrations > 100 mg/L after 24 h. However, this effect could also be ascribed to the decrease of the pH-value after 24 h (4.6 at 100 mg/L and 4.2 at 2000 mg/L) due to intrinsic properties of 2,3,3-trimethyl-3H-indole-5-carboxylic acid as Brachydanio rerio should be kept at pH-values between 6.0 and 8.0 according to the test guideline.

At a concentration of 70.7 mg/L the pH-value is 6.6 after 24 h and 5.8 after 96 h. No mortality is observed at this concentration. Thus it is most likely that the low pH-value is the reason for mortality at 100 mg/L and not the toxicity of the substance. Therefore no LC50 could be determined and just a LC0 of >=70.7 mg/L is derived.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

70.7 mg/L

Additional information

"Should read: LC0 >= 70.7 mg/L"