5-methylheptan-3-one oxime

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25-March-2014 to 22-April-2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch: PE0083052
Purity: 96.30% (sum of the two isomers)

Analytical monitoring:

yes

Details on sampling:

Range-finding test concentrations: 0.10, 1.0, 10 and 100 mg/L.
Definitive test concentrations: 2.6, 6.4, 16, 40 and 100 mg/L.

Range-finding test:
A sample of each test concentration was taken for chemical analysis from the initial range-finding test at 0 and 48 hours in order to determine the stability of the test item under test conditions. All samples were stored frozen prior to analysis. Only concentrations within the range to be used for the definitive test were analyzed.

Verification of Test Concentrations
Water samples were taken from the control and the 2.6, 6.4, 16, 40 and 100 mg/L test groups (replicates R1 - R4 pooled) at 0 and 48 hours for quantitative analysis. Samples were stored frozen prior to analysis.
Duplicate samples and samples of the 2.6 and 6.4 mg/L test groups were taken and stored frozen for further analysis if necessary.
Only samples at the No Observed Effect Concentration and above were analyzed.

Vehicle:

no

Details on test solutions:

An amount of test item (nominally 500 mg) was dissolved in test water and the volume adjusted to 5 liters to give the 100 mg/L test concentration from which a series of dilutions were made to give the remaining test concentrations of 2.6, 6.4, 16 and 40 mg/L.
Each stock solution and prepared concentration was inverted several times to ensure adequate mixing and homogeneity.
Standard reconstituted water (ISO medium) used for both the range-finding and definitive tests

Test organisms (species):

Daphnia magna

Details on test organisms:

The test was carried out using 1st instar Daphnia magna derived from in-house laboratory cultures.
Adult daphnia were maintained in 150 mL glass beakers containing Elendt M7 medium in a temperature controlled room 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 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.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

20°C

pH:

7.8 - 8.3

Dissolved oxygen:

8.8 - 9.1 mg O2/L

Nominal and measured concentrations:

Nominal: control, 2.6, 6.4, 16, 40 and 100mg/L

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

44 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CL = 35 - 54 mg/L

Details on results:

The percentage mobility in the test item groups after 48 hours was respectively 5, 0, 0, 40 and 100%. Analysis of the test preparations at 0 and 48 hours showed measured test concentrations to be near nominal values and so the effect results are based on nominal test concentrations only. The results are
- 48 Hour EC50 = 44 mg/L, 95% Confidence Limits = 35 - 54 mg/L
- No Observed effect Concentration (NOEC) = 16 mg/L
- Lowest Observed Effect Concentration (LOEC) = 40 mg/L

Results with reference substance (positive control):

The health of the Daphnia culture and the overall quality of the test organism is monitored regularly by using the reference toxicant, potassium dichromate. The most recent reference test performed in a separate study (Study Number 41400711) resulted in an EC50 (24h) of 0.87 mg/l and EC (48h) of 0.71 mg/L. The results were within the normal range for this reference item.

Range-finding Tests

In the initial range-finding test no immobilization was observed at the test concentration of 0.10 mg/L. However, immobilization was observed at 1.0, 10 and 100 mg/L with 30, 20 and 100% immobilization observed respectively.

Chemical analysis of the 1.0 and 100 mg/L test preparations (see Appendix 5) showed measured concentrations of 0.582 and 69.5 mg/L respectively at 0 hours and 0.525 and 64.9 mg/L respectively at 48 hours indicating that the test item was stable under test conditions. The low recovery from the range finding test indicates a potential error during preparation of the exposure solutions.

As results from the initial range-finding test indicated an interrupted dose response, a second range-finding test was conducted. In the second range-finding test no immobilization was observed at the test concentrations of 0.10, 1.0 and 10 mg/L. However, 100% immobilization was observed at 100 mg/L.

Based on this information test concentrations of 2.6, 6.4, 16, 40 and 100 mg/L were selected for the definitive test.

 

Definitive Test

Verification of Test Concentrations

Analysis of the test preparations at 0 and 48 hours (see Appendix 5) showed measured test concentrations to be near nominal and hence it was considered appropriate to calculate the EC50 values in terms of the nominal test concentrations only.

 

Immobilization Data

Analysis of the immobilization data by the probit method at 24 hours and by the trimmed Spearman-Karber method at 48 hours based on the nominal test concentrations gave the following results:

 

24 Hour EC50 = 90 mg/L,

48 Hour EC50 = 44 mg/L, 95% Confidence limits = 35 – 54 mg/L

 

The No Observed Effect Concentrations after 24 and 48 hours exposure were 40 and 16 mg/L respectively. The Lowest Observed Effect Concentrations after 24 and 48 hours exposure were 40 and 100 mg/L respectively. The single immobilized daphnia recorded in the 2.6 mg/L test concentration was considered to be due to natural causes.

 

Validation Criteria

The test was considered to be valid given that none 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 ≥3 mg/L in the control and test vessels.

 

Water Quality Criteria

The results of the water quality measurements are given in Table 4. Temperature was maintained at approximately 20 °C throughout the test, while there were no treatment related differences for oxygen concentration or pH.

 

Observations on Test Item Solubility

At the start and throughout the test all test preparations were observed to be clear colourless solutions.

 

CONCLUSION

Exposure of Daphnia magna to the test item has been investigated and gave the following results:

48 Hour EC50 = 44 mg/L

95% Confidence Limits = 35 - 54 mg/L

No Observed effect Concentration (NOEC) = 16 mg/L

Lowest Observed Effect Concentration (LOEC) = 40 mg/L

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the present study the 48h-EC50 was determined to be 44 mg/l based on nominal concentrations (95% Confidence Limits = 35 - 54 mg/L).

Executive summary:

Introduction

A study was performed to assess the acute toxicity of the test item to Daphnia magna. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (April 2004) No 202, "Daphnia sp., Acute Immobilisation Test" referenced as Method C.2 of Commission Regulation (EC) No. 440/2008.

 

Methods

Following preliminary range-finding tests, twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test item at concentrations of 2.6, 6.4, 16, 40 and 100 mg/L for 48 hours at a temperature of approximately 20 °C under static test conditions. The number of immobilized daphnia were recorded after 24 and 48 hours.

 

Results

Analysis of the test preparations at 0 and 48 hours showed measured test concentrations to be near nominal values and so the results are based on nominal test concentrations only. Exposure of Daphnia magna to the test item gave the following results:

 

48 Hour EC50 = 44 mg/L

95% Confidence Limits = 35 - 54 mg/L

No Observed effect Concentration (NOEC) = 16 mg/L

Lowest Observed Effect Concentration (LOEC) = 40 mg/L

Description of key information

The acute toxicity of the test item to daphnia magna has been investigated. The 48h EC50 was determined to be 44 mg/L based on nominal concentrations (95% confidence interval between 35 and 54 mg/L).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

44 mg/L

Additional information

Following a preliminary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of test item at concentrations of 2.6, 6.4, 16, 40 and 100mg/L for 48 hours at a temperature of approximately 20°C under static test conditions. The number of immobilized daphnia was recorded after 24 and 48 hours. The percentage mobility in the test item groups after 48 hours was respectively 5, 0, 0, 40 and 100%. The single immobilized daphnia recorded in the 2.6 mg/L test concentration was considered to be due to natural causes. Analysis of the test preparations at 0 and 48 hours showed measured test concentrations to be near nominal values and so the effect results are based on nominal test concentrations only.