2,3-dichlorobenzoic acid

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

48 h

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2,3-dichlorobenzoic acid

EC Number:

200-039-5

EC Name:

2,3-dichlorobenzoic acid

Cas Number:

50-45-3

Molecular formula:

C7H4Cl2O2

IUPAC Name:

2,3-dichlorobenzoic acid

Test material form:

solid: crystalline

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

yes

Details on test solutions:

The test organism was bred and held in Elendt M4 medium which was also used for preparing of test item solutions. The stock solution was prepared by measuring 225.07 mg of test item into 1 500 ml Elendt M4 growth medium. The suspension was stirred till complete dilution. After
stirring the stock solution was clear and colourless. The nominal concentration of stock solution was 150.05 mg/L.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

Test species: Daphnia magna Straus
Age: < 24 hours neonates
Origin: National Institute of Environmental Health
Date of arriving: 16 May 2013
Culture conditions: The test species is maintained in Elendt M4 medium with culture conditions at 21±1 °C and a light/dark cycle of 16/8 hours with light intensities of less than 1000 Lux. The cultures are fed with centrifugalized green alga (Pseudokirchneriella subcapitata) cells daily at weekdays.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test conditions

Test temperature:

The stock, breeding and test cultures were kept at the same conditions in thermostat (temperature: 21 ± 1 °C; light/dark cycle: 16/8 hour). These conditions ensure that the reproduction was by parthenogenesis.
The temperature of thermostat was recorded daily and registered continuously by Extech datalogger. The temperature inside the thermostat at the test vessels was measured and registered continuously by Extech SD200 thermometer and datalogger.

pH:

The pH and dissolved oxygen were measured at the beginning and at the end of the test. At the beginning of the test the pH and the dissolved oxygen were measured from the remaining test solutions of the concurrent test vessels at each dilution levels. At the end of the test the pH and the dissolved oxygen were measured in each test vessel.

Dissolved oxygen:

The pH and dissolved oxygen were measured at the beginning and at the end of the test. At the beginning of the test the pH and the dissolved oxygen were measured from the remaining test solutions of the concurrent test vessels at each dilution levels. At the end of the test the pH and the dissolved oxygen were measured in each test vessel.

Nominal and measured concentrations:

The toxic property of test item was investigated at six concentrations which were prepared by different dilutions of stock solution of test item. Elendt M4 medium was
used for dilution of stock solution. In the test the following nominal concentrations were applied: 150; 120; 90; 75; 60 and 50 mg/L. The following actual concentrations were calculated from the measured values in the test: 154.38; 122.71; 91.04; 77.05; 61.37 and 47.94 mg test item/L.

Details on test conditions:

At each concentration level four replicates were prepared. Each test vessel contained 5 daphnids in 50 ml test solution. The test vessels were covered with plastic lids and were kept in thermostat at 21 ± 1 °C and 16/8 hours light/dark cycle. The controls were kept under the same conditions in Elendt M4 medium.
Selection of young daphnids: On the first day of the test, all of juvenile daphnids were removed from the selected breeding cultures by sieving. Juvenile daphnids were disposed. Next day the neonates (which are younger than 24 hours) were separated from the parental culture by filtering and were transferred into test vessels.
Preparation of stock solution: The preparation of stock and test solutions was based on the preliminary non GLP range finding test [9]. As the Range Finding Test was not performed in compliance with the GLP-Regulations it is excluded from the Statement of Compliance in the final report, but the raw data of this test are archived under the study code of present study. For the stock solution 225.07 mg of test item was measured into 1 500 ml Elendt M4
medium. The suspension was stirred till complete dissolution. After stirring the stock solution was clear and colourless. The nominal concentration of stock solution was 150.05 mg/L.
Preparation of test solutions: Six dilution levels were prepared by mixing appropriate volume of Elendt M4 medium and stock solution of the test item. The maximum separation factor between of test vessels was 1.33. The following table shows the preparation of the different dilution levels. The volume of the prepared test solutions was 300 ml.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 154.38 mg/L

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: The test item has no toxic effect even at the highest concentration level (154.38 mg/L) the EC50 concentrations were not determinable.

Details on results:

The effective concentrations (ECx) were calculated with Probit analysis using linear max. Likelihood regression. The EC10, EC20 and EC50 were calculated for immobility at
both 24 h and 48 h period. As the test item has no toxic effect even at the highest concentration level (154.38 mg/L) the ECx concentrations were not determinable.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

As the test item has no toxic effect at even the highest concentration level (154.38 mg/L) the ECx concentrations were not determinable. According to the ToxRat
statistical software the NOEC ≥ 154.38 mg/L. In this Daphnia sp., Acute Immobilisation Test for 2,3-Dichlorobenzoic acid the results indicated that the test item is not hazardous to the aquatic environment [48 hr EC50 (for Crustacea) > 100 mg/L]