Octadecyl 3-mercaptopropionate

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:

2018-06-14 to 2019-01-04

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)

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Qualifier:

according to guideline

Guideline:

other: OECD Series on Testing and Assessment, No. 23, "Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures"

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Name: ODMP
Chemical Name: Octadecyl 3-Mercaptopropionat
CAS No.: 31778-15-1
Batch No.: 0061486
Purity: 98.5 %, according to certificate of analysis
Manufacturing Date: December 21, 2017
CoA Reference Number P907/2016
Aggregate State at Room Temperature: solid
Colour: clear, colourless
Expiry Date: December 20, 2018
Storage Conditions at Test Facility: At 4 +/- 4 °C, in the dark

Analytical monitoring:

yes

Details on sampling:

Four samples from the freshly prepared test media of all test concentrations and the control were taken at the start of the test. For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, four samples from the test media of all test concentrations and the control were collected at the end of the test (after 48 hours) by pouring together the contents of the test beakers of each treatment.

Vehicle:

no

Details on test solutions:

Test Concentrations: Due to the low limit of water solubility of the test item, a filtrate of nominal 100 mg/L and dilutions of 1:3.16, 1:10, 1:31.65 and 1:100 of this filtrate (spacing factor 3.16) and a control were tested. The analytically verified concentrations were below the limit of quantification (0.05 mg/L). Control: In the control, test water was used without addition of the test item.
Dosage of Test Item: The test item is not well soluble in test medium. To avoid physical effects of undissolved test item on the daphnids, no concentrations above the solubility limit of the test item in test water was tested. Therefore, a supersaturated stock solution of nominal 100 mg test item/L was prepared by suspending 100 mg test item in 1000 mL test water. The stock suspension was stirred for 24 hours at room temperature in the dark to dissolve as much test item as possible. Then, non-dissolved fractions of the test item were separated from the test medium by membrane filtration (0.45 µm cellulose acetate filter). The solution with dissolved test item was used as the test medium of the highest test concentration and to prepare the desired 1:3.16, 1:10, 1:31.65 and 1:100 dilutions. The test media were prepared just before introduction of the daphnids (= start of the test).

Test organisms (species):

Daphnia magna

Details on test organisms:

Species: Daphnia magna (Straus), clone 5
Age at Test Start: From 6.25 to 23.0 hours old Sex: Female
Origin: The daphnids introduced in the test were taken from ibacon's in house laboratory culture.
Breeding Conditions: The daphnids were bred in the laboratories of ibacon under similar temperature and light conditions as used in the test. The cultivation of the parental daphnids was performed in Elendt M4 medium (see 6.5). The test organisms were not first brood progeny. The daphnids in the stock culture were fed at least on all working days with green algae (Desmodesmus subspicatus) freshly grown in the laboratories of ibacon.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

Water Hardness: 2.5 mmol/L (= 250 mg/L) as Calcium Carbonate

Test temperature:

20.6 to 21.1°C at test start; 20.5 to 20.7°C at test end

pH:

8.1 to 8.2 at test start;7.9 at test end; and thus the pH-value did not vary by more than 1.5

Dissolved oxygen:

7.5 to 9.0 mg/L at test start; 8.7 mg/L at test end

Nominal and measured concentrations:

Due to the low limit of water solubility of the test item, a filtrate of nominal 100 mg/L and dilutions of 1:3.16, 1:10, 1:31.65 and 1:100 of this filtrate (spacing factor 3.16) and a control were tested. The analytically verified concentrations were below the limit of quantification (0.05 mg/L).

Details on test conditions:

Test Environment: Controlled environment room
Measurement of pH, Dissolved Oxygen and Water Temperature:
The water temperature, pH-values and dissolved oxygen concentrations were determined at test start and test end in each treatment group.
Water Temperature: 20.6 to 21.1 °C at test start; 20.5 to 20.7 °C at test end
pH-Values: 8.1 to 8.2 at test start; 7.9 at test end; and thus the pH-value did not vary by more than 1.5 Dissolved Oxygen Concentration: 7.5 to 9.0 mg/L at test start; 8.7 mg/L at test end
Light Regime: 6 h light : 8 h dark
Light Intensity: The light intensity was 370 to 700 lux (measured once during the test).

Reference substance (positive control):

yes

Remarks:

For the evaluation of the quality of the Daphnia clone and the consistency of the experimental conditions, the reference item potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions.

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

After 48 hours of exposure no immobilisation of the test animals was observed in the control and in all concentrations of the test item
No toxic effect of the test item ODMP to Daphnia magna was assessed in a static concentration-response test which was performed using nominal concentrations of up to 100 mg test item/L.

Results with reference substance (positive control):

In the most recent test with the reference item potassium dichromate performed in January 2018, the EC50 after 24 hours was determined to be 1.06 mg test item/L, indicating that the sensitivity of the daphnids was consistent with the level proposed by the OECD 202 guideline (EC50-24 h between 0.6 and 2.1 mg potassium dichromate/L).

Reported statistics and error estimates:

No statistical analysis was performed.
The EC50 could not be quantified due to the absence of toxicity of the test item. The NOEC and the LOEC were determined directly from the raw data.

Validity criteria fulfilled:

yes

Remarks:

Control Immobilisation Rate was 0 % and furthermore no daphnid showed signs of disease or stress. Dissolved Oxygen Concentration was above or equal 8.7 mg O2/L in the control and test vessels at the end of the test.

Conclusions:

After 48 hours of exposure no immobilisation of the test animals was observed in the control and in all concentrations of the test item
No toxic effect of the test item ODMP to Daphnia magna was assessed in a static concentration-response test which was performed using nominal concentrations of up to 100 mg test item/L.

Executive summary:

A short-term toxicity study according to OECD TG 202 was conducted to determine the influence of the test item ODMP on the mobility of Daphnia magna.

This study encompassed 6 treatment groups (5 dose rates of the test item and a control) each containing 20 individuals. The mobility of the daphnids was determined in a static 48-hour test by visual observation after 24 and 48 hours.

Due to the low limit of water solubility of the test item, a filtrate of nominal 100 mg/L and dilutions of 1:3.16, 1:10, 1:31.65 and 1:100 of this filtrate (spacing factor 3.16) and a control were tested. The analytically verified concentrations were below the limit of quantification (0.05 mg/L).

After 48 hours of exposure no immobilisation of the test animals was observed in the control and up to and including the filtrate of 100 mg test item per L.

Analytical test results:

The quantification of the test item ODMP in the test samples was performed using gas chromatography with MS detection. In all samples, from test start and test end (48 hours test duration), the test item concentration was below the LOD of the method (0.05 mg test item/L) due to the low water solubility of the test item. During the test the algae were exposed to an amount of test item below the detection limit of the method applied.

No toxic effect of the test item ODMP to Daphnia magna was assessed in a static concentration-response test which was performed using nominal concentrations of up to 100 mg test item/L.

The filtrate of a 100 mg test item/L solution was used as highest test concentration, but analytical verification of the concentrations was below the limit of detection of 0.05 mg test item/L. The 48-hour NOEC was determined to be at least the filtrate of nominal 100 mg test item/L. The NOEC might even be higher than this concentration, but concentrations in excess of nominal 100 mg test item/L or the limit of solubility have not been tested according to the recommendations of the test guidelines. The 48-hour LOEC and the 48-hour EC50 were clearly higher than the filtrate of nominal 100 mg test item/L. These values could not be quantified due to the absence of toxicity of ODMP up to the filtrate of nominal 100 mg test item/L, the concentration representing the limit of solubility. The initial concentrations and the maintenance of the exposure concentrations during the test could not be verified in the analytical part. The water solubility and thus test item concentrations were below the limit of detection of 0.05 mg test item/L.

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

Description of key information

According to the results of the experimental test carried out, ODMP is not toxic to daphnia. The 48 -hour EC50 were clearly higher than the filtrate of nominal 100 mg test item/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

100 mg/L

Additional information

A short-term toxicity study according to OECD TG 202 was conducted to determine the influence of the test item ODMP on the mobility of Daphnia magna.

This study encompassed 6 treatment groups (5 dose rates of the test item and a control) each containing 20 individuals. The mobility of the daphnids was determined in a static 48-hour test by visual observation after 24 and 48 hours.

Due to the low limit of water solubility of the test item, a filtrate of nominal 100 mg/L and dilutions of 1:3.16, 1:10, 1:31.65 and 1:100 of this filtrate (spacing factor 3.16) and a control were tested. The analytically verified concentrations were below the limit of quantification (0.05 mg/L).

After 48 hours of exposure no immobilisation of the test animals was observed in the control and up to and including the filtrate of 100 mg test item per L.

Analytical test results:

The quantification of the test item ODMP in the test samples was performed using gas chromatography with MS detection. In all samples, from test start and test end (48 hours test duration), the test item concentration was below the LOD of the method (0.05 mg test item/L) due to the low water solubility of the test item. During the test the algae were exposed to an amount of test item below the detection limit of the method applied.

No toxic effect of the test item ODMP to Daphnia magna was assessed in a static concentration-response test which was performed using nominal concentrations of up to 100 mg test item/L.

The filtrate of a 100 mg test item/L solution was used as highest test concentration, but analytical verification of the concentrations was below the limit of detection of 0.05 mg test item/L. The 48-hour NOEC was determined to be at least the filtrate of nominal 100 mg test item/L. The NOEC might even be higher than this concentration, but concentrations in excess of nominal 100 mg test item/L or the limit of solubility have not been tested according to the recommendations of the test guidelines. The 48-hour LOEC and the 48-hour EC50 were clearly higher than the filtrate of nominal 100 mg test item/L. These values could not be quantified due to the absence of toxicity of ODMP up to the filtrate of nominal 100 mg test item/L, the concentration representing the limit of solubility. The initial concentrations and the maintenance of the exposure concentrations during the test could not be verified in the analytical part. The water solubility and thus test item concentrations were below the limit of detection of 0.05 mg test item/L.