(6-Bromo-2-pyridinyl)(4-methylphenyl)methanone

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:

Experimental start date 03 December 2018, Experimental completion date 31 January 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

Study Plan stated Daphnia cultures to be fed a Tetramin suspension, however the range-finding and definitive test cultures were fed GM 300 fish food suspension. Deviation was considered to have not affected the integrity or validity of the study.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

1

Reference substance name:

2-bromo-6-(4-methylbenzoyl)pyridine

EC Number:

618-079-0

Cas Number:

87848-95-1

Molecular formula:

C13H10BrNO

IUPAC Name:

2-bromo-6-(4-methylbenzoyl)pyridine

Specific details on test material used for the study:

Identification : 2-Bromo-6-(4-toluoyl)pyridine
CAS Number : 87848-95-1
Batch: 800295520
Purity: 99.5%
Physical State/Appearance :
- Envigo : Beige Powder
- Sponsor : White to buff powder
Expiry Date : 03 July 2020
Storage Conditions : Room temperature in the dark

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Preparation of Test Samples
The test samples were analyzed on the day of receipt. The test item was extracted from the test samples using a solid phase extraction cartridge (C18, 500 mg/ 3 mL). The cartridge was packed with glass wool prior to being pre-conditioned with 10 mL of acetonitrile and 10 mL of water. The samples were drawn through the cartridge under reduced pressure. Subsequently, the cartridge was eluted with 5 mL of acetonitrile into a 10 mL volumetric flask. The solution was made up to the mark with water. If required the test samples were further diluted with water: acetonitrile (50:50 v/v).

Test solutions

Vehicle:

not specified

Details on test solutions:

A nominal amount of test item (550 mg) was dispersed in 11 liters of test water with the aid of propeller stirring at approximately 1500 rpm for 24 hours. After 24 hours the stirring was stopped and any undissolved test item was removed by filtration through a 0.2 μm Gelman Acrocap filter (the first approximate 500 mL used to pre-condition the filter was discarded) to give a 100% v/v saturated solution of the test item. A series of dilutions was made from this saturated solution to give further test concentrations of 56, 32, 18 and 10% v/v saturated solution.
Each prepared concentration was inverted several times to ensure adequate mixing and homogeneity.
The concentration and stability of the test item in the test preparations was verified by chemical analysis at 0 and 48 hours

Test organisms

Details on test organisms:

Test System and Supporting Information
The test was carried out using first instar Daphnia magna derived from in-house laboratory cultures.
Adult daphnids were maintained in 150 mL glass vessels containing 100 mL Elendt M7 medium in a temperature controlled room maintaining the water temperature at approximately 20 °C. The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods. Each culture was fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and GM 300 fish feed suspension. Culture conditions ensured that reproduction was by parthenogenesis. Gravid adults were isolated the day before initiation of the test, such that the young daphnids produced overnight were less than 24 hours old. These young were removed from the cultures and used for testing. The diet and diluent water are considered not to contain any contaminant that would affect the integrity or outcome of the study.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Test temperature:

19-21°C

pH:

7.8-8.0

Dissolved oxygen:

8.9-9.4 mg O2/L

Nominal and measured concentrations:

Nominal: 10, 18, 32, 56 and 100% v/v saturated solution.
Analysis of the test preparations at 0 hours showed measured test concentrations to range from 0.45 to 4.9 mg/L. There was no significant change in the measured concentrations at 48 hours (93% to 105% of the 0-Hour measured test concentrations) and so the results are based on 0-Hour measured test concentrations.
Measured: 0.45, 0.81, 1.4, 2.4, 4.9 mg/L

Details on test conditions:

Test Water
Reconstituted water (Elendt M7 medium) was used for both the range-finding and definitive tests

Exposure Conditions
In definitive test 150 mL glass vessels containing approximately 100 mL of test preparation were used. At the start of the test five daphnids were placed in each test and control vessel at random, containing the test preparations. Four replicate test and control vessels were prepared. The test vessels were then covered to reduce evaporation and maintained in a temperature controlled room maintaining the water temperature at 18 to 22 °C with a maximum deviation of ±1 °C and a photoperiod of 16 hours light (between 200 and 1200 Lux) and 8 hours darkness with 20 minute dawn and dusk transition periods. The daphnids were not individually identified, received no food during exposure and the test vessels were not aerated.
The control group was maintained under identical conditions but not exposed to the test item.
The test preparations were not renewed during the 48-Hour exposure period.

Assessments
Test Organism Observations
Any immobilization or adverse reactions to exposure were recorded at 24 and 48 hours after the start of exposure. The criterion of effect used was that Daphnia were considered to be immobilized if they were unable to swim within 15 seconds after gentle agitation.

Water Quality Criteria
Water temperature was recorded daily throughout the test. Dissolved oxygen concentrations and pH were recorded at the start and termination of the test. The pH and dissolved oxygen concentration were measured using a Hach Flexi handheld meter whilst the temperature was measured using a Hanna Instruments HI 93510 digital thermometer.
The light intensity during the light period was measured using an ATP Instrumentation Lux meter.
The appearance of the test media was recorded daily.

Verification of Test Concentrations
Samples were taken from the control and each of the test groups from the bulk test preparation at 0 hours and from the pooled replicates at 48 hours for immediate quantitative analysis. Duplicate sets of samples were taken at 0 and 48 hours and stored frozen for further analysis if necessary.

Data Evaluation
Statistical Analysis
The EC50 value and associated confidence limits at 24 and 48 hours and the slope of the response curve and its standard error were calculated by Probit analysis using Linear Maximum-Likelihood regression. The Lowest Observed Effect Concentration (LOEC) and the No Observed Effect Concentration (NOEC) at 24 and 48 hours were calculated using the Step-down Cochran-Armitage Test Procedure. All results were calculated using the ToxRat Professional computer software package (TOXRAT).

Validation Criteria
The results of the test are considered valid if the following performance criteria are met:
• No more than 10% of the control daphnids show immobilization or other signs of disease or stress (e.g. discoloration or unusual behavior such as trapping at the surface water).
• The dissolved oxygen concentration at the end of the test is equal to or greater than 3 mg/L in the control and test vessels.

Reference substance (positive control):

yes

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

3.2 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 2

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1.4 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 3

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

2.4 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

Definitive Test
Verification of Test Concentrations
Analysis of the test preparations at 0 hours showed measured test concentrations to range from 0.45 to 4.9 mg/L. There was no significant change in the measured concentrations at 48 hours (93% to 105% of the 0-Hour measured test concentrations) and so the results are based on 0-Hour measured test concentrations.

Immobilization Data
Analysis of the immobilization data by Probit analysis using Linear Maximum-Likelihood regression method at 24 and 48 hours based on the 0-Hour measured test concentrations gave the following results:
24h EC50 = 4.4 mg/L
48h EC50 = 3.2 mg/L (95%CL: 2.7 - 3.9)
The No Observed Effect Concentrations (NOEC) after 24 and 48 hours exposure were 2.4 and 1.4 mg/L, respectively. The Lowest Observed Effect Concentrations (LOEC) after 24 and 48 hours exposure were 4.9 and 2.4 mg/L, respectively.
The slopes and their standard errors of the response curves at 24 and 48 hours were 20 (standard error = 0.49) and 5.9 (standard error = 0.038) respectively.

Sub-Lethal Effects
Sub-lethal effects of exposure were observed in the control, 2.4 and 4.9 mg/L test concentrations. These responses were trapped at the surface, reduced mobility and pale in coloration.

Validation Criteria
The test was considered to be valid given that no more than 10% of the control daphnids showed immobilization or other signs of disease or stress and that the oxygen concentration at the end of the test was equal to or greater than 3 mg/L in the control and test vessels.

Water Quality Criteria
Temperature was maintained at 19 °C to 21 °C throughout the test, while there were no treatment related differences for oxygen concentration or pH.
Throughout the test the light intensity was observed to be in the range 790 to 941 Lux.

Observations
At the start and throughout the test all control and test solutions were observed to be clear colorless solutions.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Exposure of Daphnia magna to the test item has been investigated and gave the following results based on the 0-Hour measured test concentrations:
EC50 = 3.2 mg/L (95%CL: 2.7 - 3.9)
NOEC = 1.4 mg/L
LOEC = 2.4 mg/L