Octanoic acid, 1,1'-(1,3-propanediyl) ester

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From November 2021 to July , 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed according to OECD and according to GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Version / remarks:

2012

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.20 (Daphnia magna Reproduction Test)

Version / remarks:

None

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

GLP according to Chemikaliengesetz and Directive 88/320/EEC

Specific details on test material used for the study:

CAS number: 56519-71-2
Vapour pressure: 0.0791 mPa (20°C)
Density: 0.93 g/cm³ (20°C)
Log Kow: 7.6

Analytical monitoring:

yes

Details on sampling:

Sampling was performed three times per week in fresh and aged test media.
Samples of fresh test solutions were taken from the test solution preparations before adding of daphnids.
For aged test solutions, samples were taken from a representative test vessel per treatment.
In addition, the test item concentrations were measured in the acetonic stock solutions once per week. Samples were stabilized with ACN immediately after sampling and stored at ≤ -18 °C until analysis.

Vehicle:

yes

Remarks:

Acetone was used as test vehicle

Details on test solutions:

The test was performed as a limit test with one loading rate of 10 mg/L test item.
The water control consisted of dilution water only. Since the test item was applied using a solvent, an additional solvent control containing the same concentration of solvent as all test concentrations (0.01 % v/v, corresponding to 0.1 mL/L) was prepared.
Test solutions were exchanged three times per week.
For preparation of test solutions, an appropriate amount of the individual acetonic application solution was added to e.g. 1000 mL of test medium.
Care was taken to ensure that the amount of acetone was the same in all test concentrations and did not exceed 0.01 % v/v, corresponding to 0.1 mL/L. The test solutions were sonicated for 1 hour and afterwards stirred for the following 23 hours to ensure a homogenous distribution of the test item. To separate insoluble parts from the aqueous phase the test solutions were left to stand for 24 hours. The first approximately 100 - 200 mL were drained from the port at the bottom of the glass flask and then discarded to remove any insoluble test item which might have dropped to the ground. The following about 500 - 600 mL were released and used as test solution.
The test solutions were freshly prepared before test start and before each renewal three times a week following the same procedure.

Test organisms (species):

Daphnia magna

Details on test organisms:

The test organisms were young Daphnia magna, 4 – 24 hours old. Origin of the cladocerans is the German Federal Environment Agency, Institut für Wasser-, Boden- und Lufthygiene. Specimens used in the test are bred in the laboratory of the Fraunhofer IME for over 15 years.

Adult Daphnia, at least 3 weeks old, were separated from the stock population by sieving. Batches of 30 to 50 animals were held at room temperature (around 20°C in ca. 1.8 L dilution water for one week.
During this week, the daphnids were fed daily with an algal suspension (Desmodesmus subspicatus) and ArtemioFluid (JBL GmbH & Co. KG). Algae growing in the log-phase were centrifuged and the pellet was re-suspended in a few mL of medium. 5 mL of this suspension was given to about 1.8 L Daphnia medium. The water was changed three times per week. Newborn D. magna were separated by sieving, the first generation was discarded. Individuals applied in the test were transferred with a bore Pasteur pipette a few hours after sieving to ensure applying only healthy specimens.

Test type:

semi-static

Water media type:

freshwater

Remarks:

Purified, Cu-reduced tap water was used as holding- and dilution water. The purification includes filtration with activated charcoal and aeration. To avoid copper contamination, plastic water pipes are used for the testing facilities

Limit test:

yes

Total exposure duration:

21 d

Post exposure observation period:

No post exposure observation

Hardness:

Hardness of the Cu-reduced water was below the recommended range (>140 mg/L as CaCO3) for Daphnia magna indicated in the guideline. Therefore, the dilution water was enriched with an appropriate amount of CaCl¬2 to increase the hardness, resulting in values of about 250 – 350 mg CaCO3/L

Test temperature:

The test temperature during the test was at 20°C ± 2°C.

pH:

The pH was within a range of 6 – 9 in fresh test solutions (7.50 – 8.27). In aged test solutions, the pH was between 8.03 and 9.33.

Dissolved oxygen:

The dissolved oxygen saturation was between 5.81 mg/L and 14.1 mg/L (63.9 – 169 % air saturation).

Salinity:

None

Nominal and measured concentrations:

The test was performed at one loading rate of 10 mg/L test item and with water and solvent controls.

Details on test conditions:

- Test Environment: Controlled environment room
- Oxygen concentration, pH value, and temperature of the test solutions were checked directly before adding the animals and at each water renewal in new and aged test solutions.
- Hardness was checked in the control and the loading rate once per week.
- pH-Value of Test Medium: pH 6 - 9; the pH-value should not vary by more than 1.5 units
- Oxygen Concentration: >= 3 mg/L
- Water Temperature: 18 °C - 22 °C
- Measurement of Light Intensity: The light intensity was measured at least once during the test.
- Light Regime: 16 h light : 8 h dark
- Light Intensity: 10 - 1200 lux
- Recording: Test conditions were recorded with suitable instruments and documented in the raw data.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

immobilisation

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

immobilisation

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: length

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: length

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: age of first reproduction

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: age of first reproduction

Details on results:

- First of all, no individual died in the control or solvent control.
- One daphnid died in the treatment level of 10 mg test item/L (nominal). There was no significant difference in survival of individuals between the controls and the treatment level.
- In addition, no significant reduction of the adult body length of individuals measured at test end was observed between the controls and the treatment level. Daphnids showed a mean size of 4.32 mm in the pooled control and 4.16 mm in the treatment level.
- No other abnormalities like discoloration or inactivity were observed. No other clinical signs as presence of winter eggs occurred.

- The cumulative offspring per survived and introduced parent was at 93.5 in the control and at 124.3 in the solvent control. For comparison of the treatment with the controls, the pooled reproduction data of control and solvent control were used.
- The pooled control showed a cumulative offspring of 108.9 juveniles per adult daphnid. There was no significant difference between the controls and the treatment of 10 mg test item/L (nominal) with 105.9 juveniles per survived adult daphnid. Thus, no significant effect in terms of a reduced reproduction of daphnids was identified.

- For the age of the first reproduction no significant effect could be observed between the pooled controls and the treatment level. Age at the first brood was at 10.1 days for the controls and at 11.1 days for the treatment level.

Results with reference substance (positive control):

The results of the latest reference study (September 2021) were in agreement with historical 24 h EC50-values obtained in the laboratory, and the stated range given in the OECD guideline (EC50 = 0.6 – 2.1 mg/L).
Immobilization after 24 h:
Control: 5.0 %
0.40 mg RS/L: 5.0 %
0.60 mg RS/L: 15.0 %
0.90 mg RS/L: 25.0 %
1.35 mg RS/L: 90.0 %
2.00 mg RS/L: 100 %
24 h EC50 value:
Immobilization: 0.937 mg/L (95% CL : 0.565 – 1.561 mg/L)

Validity criteria fulfilled:

yes

Remarks:

The test fulfils all validity criteria of the OECD guideline 211

Conclusions:

The 21-day toxicity of the test item Propanediol Dicaprylate to the test organism Daphnia magna was determined in a semi-static system (OECD 211) exposed to one nominal loading rate of 10.0 mg/L with three media renewals per week.

The concentrations of the test item in the test media were determined by chemical analysis of the test item in the aqueous phase of the control and the treatment level using UHPLC-MS/MS. However, it was not possible to quantify reasonable test item concentrations in the aqueous samples taken throughout the study. Measurements of the acetonic stock solutions used for application of the test item showed a correct dosing. Thus, the effect assessment was performed based on the nominal loading rate of 10 mg test item/L.

During the 21-day exposure period, no significant effect of the test item on the investigated endpoints reproduction of survived and introduced parent daphnids, immobilisation of parent daphnids, length at test end, age of first reproduction and development rate of the test organisms Daphnia magna were observed.

For the relevant endpoints reproduction and survival, the NOEL was set to be higher than the applied loading rate and is therefore determined to be ≥ 10 mg test item/L nominal loading. The LOEL was determined to be > 10 mg test item/L nominal loading.

Executive summary:

The influence of the test item Propanediol Dicaprylate on the reproduction of aquatic invertebrates, represented by Daphnia magna, was investigated. The test was performed as a limit test with one loading rate in a 21-day semi-static exposure according to the OECD guideline 211. Untreated control replicates were run in parallel. The control and the treatment group consisted of 10 replicates with one daphnid each (individual exposure). Effects on the reproductive performance, survival, growth (adult length at test termination), development rate and intrinsic rate r of population increase were investigated.

For the investigation of reproduction, the daphnids were exposed to a control, a solvent control and one nominal loading rate of 10 mg test item/L.

The test item concentrations in the treatment level were measured in aqueous samples at fresh and representative aged test solutions three times per week at media renewal. In addition, samples of acetonic stock solutions used for application of the test item were measured once per week.
The concentrations of the test item in the test media were determined by chemical analysis of the test item in the aqueous phase of the control and the treatment level using UHPLC-MS/MS. However, it was not possible to quantify reasonable test item concentrations in the aqueous samples taken throughout the study. Measurements of the acetonic stock solutions used for application of the test item showed a correct dosing. Thus, the effect assessment was performed based on the nominal loading rate of 10 mg test item/L.

Due to the use of a solvent for application of the test item, a solvent control was introduced.
The evaluation of effects was based on the pooled data of the control and the solvent control.

If the parental mortality follows a concentration-response pattern, according to the guideline OECD 211 [5], it is required to report the NOEC/NOEL and ECX/ELX for the cumulative offspring per introduced parent provided these values are lower than in the cumulative offspring per survivor. The recent study was performed as limit test with one loading rate. Therefore, the Cochram-Armitage test could not be performed. However, no immobility occurred in the tested loading rate. Thus, according to OECD 211 NOEL values should be reported based in the cumulative offspring per survivor. Nevertheless, since no immobility was observed, NOEL values are the same for the cumulative offspring per survived and per introduced daphnid. Therefore, both endpoints are reported.
To be valid, the maximum control mortality in females must not exceed 20% and the mean offspring number at day 21 must be at least 60.0. In present test, mortality was 0% and mean offspring number was 108.9. With respect to all these criteria the test is valid.

The NOEL and LOEL values for the investigated parameters are presented based on the nominal loading rates of the test item.
After 21 days, no statistically significant effect was observed for the investigated endpoints reproduction of survived and introduced parent daphnids, immobilisation of parent daphnids, length at test end, age of first reproduction and development rate of the test organisms Daphnia magna were observed.

For the relevant endpoints reproduction and survival, the NOEL was set to be higher than the applied loading rate and is therefore determined to be ≥ 10 mg test item/L nominal loading. The LOEL was determined to be > 10 mg test item/L nominal loading.

Table: NOEL and LOEL values based on the nominal loading rate of the test item for the exposure of Daphnia magna for 21 days.

Parameter	LOEL	NOEL
Nominal Loading rate [mg/L]
Offspring per survived parent	> 10.0	≥ 10.0
Offspring per introduced parent	> 10.0	≥ 10.0
Immobility	> 10.0	≥ 10.0
Length	> 10.0	≥ 10.0
Age of first reproduction	> 10.0	≥ 10.0
Development rate	> 10.0	≥ 10.0

Conclusion
The test organisms Daphnia magna showed no significant effects after the 21-day exposure period to the test item Propanediol Dicaprylate in terms of the relevant endpoints : reproduction, immobilisation, length and age of first reproduction.

For these endpoints, the NOEL was set to be higher than the applied loading rate and is therefore determined to be ≥ 10 mg test item/L nominal loading. The LOEL was determined to be > 10 mg test item/L nominal loading.

Description of key information

the NOEL was set to be higher than the applied loading rate and is therefore determined to be ≥ 10 mg test item/L nominal loading. The LOEL was determined to be > 10 mg test item/L nominal loading.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Remarks:

Relevant endpoints : reproduction, immobilisation, length and age of first reproduction

Effect concentration:

>= 10 mg/L

Additional information

The test organisms Daphnia magna showed no significant effects after the 21-day exposure period to the test item Propanediol Dicaprylate in terms of the relevant endpoints : reproduction, immobilisation, length and age of first reproduction.

For these endpoints, the NOEL was set to be higher than the applied loading rate and is therefore determined to be ≥ 10 mg test item/L nominal loading. The LOEL was determined to be > 10 mg test item/L nominal loading.