N-octylpyridin-4-amine

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 09 April 2018, Experimental completion date 23 May 2018

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)

Deviations:

yes

Remarks:

At the time of signing the study plan, no test item information was available for the test item. Test item information was subsequently provided, however, a study plan amendment to the study plan was not issued. The information is included in the report.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

N-octylpyridin-4-amine

EC Number:

265-019-0

EC Name:

N-octylpyridin-4-amine

Cas Number:

64690-19-3

Molecular formula:

C13H22N2

IUPAC Name:

N-octylpyridin-4-amine

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Verification of Test Concentrations
Samples were taken from the control and each test group from the bulk test preparation at 0 hours and from the pooled replicates at 48 hours for quantitative analysis. All samples were stored frozen prior to analysis. The chemical analysis was conducted by the Residue Analytical Services at Envigo - Eye. A set of duplicate samples was taken on each sampling occasion and stored frozen in the Department of Ecotoxicology at Envigo – Shardlow, for further analysis if necessary.

Test solutions

Vehicle:

no

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 in order to pre-condition the filter was discarded), to give a 100% v/v saturated solution. A series of dilutions was made from this saturated solution to give further test concentrations of 0.1, 0.32, 1.0, 3.2 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 were verified by chemical analysis at 0 and 48 hours by the Residue Analytical Services at Envigo - Eye

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

The test was carried out using first instar Daphnia magna derived from in-house laboratory cultures.
Adult daphnids were maintained in 150 mL glass beakers containing 100 mL Elendt M7 medium in a temperature controlled room maintaining the water temperature at 18 to 22 °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 Tetramin® flake food 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.
A positive control (Envigo study number LK67NP) used potassium dichromate as the reference item. The positive control was conducted between 23 January 2018 to 25 January 2018.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

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 daphnids were considered to be immobilized if they were unable to swim within 15 seconds after gentle agitation.

Test conditions

Details on test conditions:

Exposure Conditions
As in the range-finding tests 150 mL glass beakers 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 held 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 exposure period.

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 test group from the bulk test preparation at 0 hours and from the pooled replicates at 48 hours for quantitative analysis. All samples were stored frozen prior to analysis. The chemical analysis was conducted by the Residue Analytical Services at Envigo - Eye. A set of duplicate samples was taken on each sampling occasion and stored frozen in the Department of Ecotoxicology at Envigo – Shardlow, for further analysis if necessary.

Statistical Analysis
The EC50 values and associated confidence limits at 24 and 48 hours and the slope of the response curve and its standard error were calculated by Logit 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.

Major Computerized Systems
The following computerized system was used in the study:
ToxRat Statistics
Delta control system Building management

Results and discussion

Effect concentrations

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.94 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

Verification of Test Concentrations
Chemical analysis of the test preparations at 0 hours showed measured test concentrations to range from 0.044 to 5.2 mg/L. With the exception of the 0.10% v/v saturated solution which declined from 0.044 to 0.034 mg/L (77% of the 0-Hour measured test concentration), there was no significant change in the measured concentrations at 48 hours. Given that no immobilization of the Daphnia was observed in the 0.32% v/v saturated solution it was considered appropriate to base the results of the test on the 0-Hour measured test concentrations of 0.044, 0.13, 0.50, 1.4 and 5.2 mg/L.

Immobilization Data
Analysis of the immobilization data by Logit analysis using Linear Maximum-Likelihood regression at 24 and 48 hours based on the 0-Hour measured test concentrations gave the following results:
EC50 24h: 1.7 mg/L
EC50 24h: 0.94 mg/L
The NOEC after 24 and 48 hours exposure was 0.50 mg/L. The LOEC after 24 and 48 hours exposure was 1.4 mg/L. The slopes and their standard errors of the response curves at 24 and 48 hours were 7.5 (standard error = 0.061) and 8.0 (standard error = 0.056) respectively.

Sub-Lethal Effects
Sub-lethal effects of exposure were observed in all test concentrations except at 5.2 mg/L where all Daphnia were immobilized. These responses were 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 20 °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 676 to 705 Lux.

Observations on Test Item Solubility
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:
24h EC50: 0.94 mg/L
NOEC: 0.50 mg/L
LOEC: 1.4 mg/L