Potassium isooctadecanoate

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:

2017

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

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Product description: Potassium isooctadecanoate/potassium isostearate
Name: Isooctadecanoic acid, potassium salt
CAS No.: 66469-15-6
Physical state: off white to yellowish solid at 20 °C
Batch No.: PFS-755-169
Re-certification date of batch: 12 December 2017
Purity: 100 % (UVCB)
pH, 10% in DI water 8.0 - 9.0
Stability: stable under test conditions
Storage condition of test material: Room temperature, protected from light

Analytical monitoring:

yes

Details on sampling:

Samples were taken in 3 replicates from three test concentrations (50 mg/l, 200 mg/l and 800 mg/l loading rate) and the control (NC) at 0 h, 24 h, 48 h and 72 h from the separate test vessels without daphnids. For stabilisation of the sample 2 mL acetonitrile were added into the 4 mL glass vials. With every sampling 2 mL test-solution were taken and filled into 4 mL glass vials. The pipette tip was rinsed with the test solution-acetonitril-mixture in the glass vial two or three times. Two of the replicates were stored at 5°C +/- 3°C until being sent to the analytical laboratory. The third retain samples were kept in the freezer until finalization of the study. Proper departure and arrival of the samples were documented.

Vehicle:

no

Details on test solutions:

Due to the low solubility of the test item, the test was performed with a water saturated fraction in M4 medium with a nominal concentration (LR) of 800 mg/L. Therefore 401.7 mg of the test item was added to 500 mL M4 medium. The solution was shaken in a 500 mL glass bottle for 24 h (+/- 1h) in the dark at room temperature (25.7 – 25.9 °C). For shaking an overhead shaker was used (about 15 rpm). After shaking was stopped, undissolved material were allowed to sediment for a period of 25 min After the settling time, the saturated fraction of the solution was transferred into a beaker glass by siphoning. The solution was
turbid. Therefore the solution was filtered with a glass fibre filter (1-2 µm, MN 85/70 BF; Lot:106572/1) as a pre-filtration first and in the second step with a nylon filter (0.45 µm, PES Nalgene, Lot: 1191856) to prepare a clear test solution. The pH was 8.6. The controls (NC) with M4 medium only was treated the same way as the test solution. Further test concentrations was prepared by diluting the test solution (saturated fraction) with M4 medium.

Test organisms (species):

Daphnia magna

Details on test organisms:

The test organism Daphnia magna Straus originates from the clone breeding of the Federal Environment Agency, department IV 2.4, Berlin, and was cultivated at Hydrotox GmbH since October 2012. The daphnids are cultured at 20 ± 2 °C with 16 h light : 8 h dark and placed into fresh M4 medium twice a week. They are kept at approx. 10 animals / 200 mL and fed on workdays with Desmodesmus subspicatus algae corresponding to 0.1 mg C × daphnid-1 × day-1. The test organisms used were 0.75 - 21 h old at the start of the test. Quality assurance takes place at regular intervals by testing the sensitivity of the test organisms
to the reference item potassium dichromate. The recent quality testing was performed in February 2017 with EC50 = 1.32 mg/L (1.24 – 1.41 mg/L Cl-95%) (24 h) which is in the declared range of 0.6 - 2.1 mg/L (24 h) according to OECD 202.

Test type:

static

Water media type:

freshwater

Remarks:

M4 medium

Limit test:

no

Total exposure duration:

48 h

Hardness:

M4 medium

Test temperature:

The temperature during the exposure was 20.8 – 21.3 °C (required 18 - 22 °C, constant within ± 1 °C).

pH:

The pH was 7.9 - 7.7 in the control and 7.9 – 8.6 in the test item treatments.

Dissolved oxygen:

The dissolved oxygen concentration was 8.0 – 8.3 mg/L in the control and 6.8 – 8.0 mg/L in the test item treatments.

Salinity:

M4 medium

Conductivity:

M4 medium

Nominal and measured concentrations:

A preliminary test without GLP was performed before start of this GLP-study. Nominal concentrations of 10, 100 and 1000 mg/L test item resulted in 0, 0 and 100 % immobility after 48 h exposure, respectively. But the mobility of daphnids in 100 mg/L has clearly slowed. In the present study, five nominal Loading Rates (LR) of 50 - 800 mg/L test item were applied.

Analysis
In the control, the test item was not detected. In the test item treatments the test item was detected but the calculated concentration of the samples was below the limit of quantification (< LOQ)of the validated method and therefore no calculation of the final concentration (taking into account the dilution factor of 2) were possible. A calibration below 10 mg/L was not feasible in the test medium.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOELR

Effect conc.:

200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EL10

Effect conc.:

155.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

mobility

Remarks on result:

other: (95%-CI: n.d.)

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

185.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

mobility

Remarks on result:

other: 95%-CI: n.d.

Duration:

24 h

Dose descriptor:

NOELR

Effect conc.:

200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

LOELR

Effect conc.:

400 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EL10

Effect conc.:

318.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

mobility

Remarks on result:

other: (95%-CI: 197.9 – 400.0)

Duration:

24 h

Dose descriptor:

EL50

Effect conc.:

572.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

mobility

Remarks on result:

other: (95%-CI: 470.2 – 726.3)

Details on results:

The Daphnia magna acute immobilisation test was performed with five loading rates between 50 mg/L and 800 mg/L. Because of the low solubility of the test item, resulting in a very low recovery rate, all results are given in relation to the nominal test item concentrations. The following results were obtained:
ELR50 (24 h): 572.9 mg/l (95%-CI: 470.2 – 726.3 mg/l)
ELR50 (48 h): 185.9 mg/l (95%-CI: n.d.)

Results with reference substance (positive control):

Quality assurance takes place at regular intervals by testing the sensitivity of the test organisms to the reference item potassium dichromate. The recent quality testing was performed in February 2017 with EC50 = 1.32 mg/L (1.24 – 1.41 mg/L Cl-95%) (24 h) which is in the declared range of 0.6 - 2.1 mg/L (24 h) according to OECD 202.

Reported statistics and error estimates:

The effect occurrence after 24 h and 48 h exposure was calculated. With the statistical software ToxRat Professional 2.10.05 (ToxRat Solutions GmbH, Alsdorf, Germany), EC and LOEC/NOEC were determined as far as mathematically possible.

Results of the D. magna Immobilisation Test

Immobility after 24 h and 48 h exposure

Nominal test item concentration [mg/L]	Immobile Daphnia (replicates 1 – 4)												Immobility [%]
	0h				24 h				48 h				24 h	48 h
	1	2	3	4	1	2	3	4	1	2	3	4
NC	0	0	0	0	0	0	0	0	0	0	0	0	0	0
50	0	0	0	0	0	0	0	0	0	0	0	0	0	0
100	0	0	0	0	0	0	0	0	0	0	0	0	0	0
200	0	0	0	0	0	0	0	0	4	4	3	3	0	70
400	0	0	0	0	2	0	1	2	5	5	5	5	25	100
800	0	0	0	0	4	3	4	4	5	5	5	5	75	100

Effect concentrations

The effect concentrations after 24 h and 48 h exposure were calculated with the statistical software ToxRat Professional 3.2.1. Although the measured test item concentrations are not within ± 20 % of the nominal concentrations, all results are given in relation to the nominal test item concentrations. As only three of the five test item concentrations were measured within the chemical analysis and the results of the measurement showed a high variability and below the limit of quantification, it is not feasible to conduct the data evaluation based on the measured test item concentrations.

Effect concentration after 24 h and 48 h exposure

Lowest/No Observed Loading Rate (95 % Confidence Limits (CL))	Nominal loading rate [mg/l]
	24 h	48 h
ELR50	572.9 (95%-CI: 470.2 – 726.3)	185.9 (95%-CI: n.d.)
ELR10	318.6 (95%-CI: 197.9 – 400.0)	155.5 (95%-CI: n.d.)
LOELR	400.0	200.0
NOELR	200.0	100.0

n.d.: not determined due to mathematical reasons or inappropriate data

Validity criteria fulfilled:

yes

Conclusions:

The Daphnia magna acute immobilisation test was performed with five loading rates between 50 mg/L and 800 mg/L. Because of the low solubility of the test item, resulting in a very low recovery rate, all results are given in relation to the nominal test item concentrations. The following results were obtained:
ELR50 (24 h): 572.9 mg/l (95%-CI: 470.2 – 726.3 mg/l) and ELR50 (48 h): 185.9 (95%-CI: n.d.).

Executive summary:

In an OECD 202 GLP study the Daphnia magna acute immobilisation of the test item was analyzed with five loading rates between 50 mg/L and 800 mg/L. Because of the low solubility of the test item, resulting in a very low recovery rate, all results are given in relation to the nominal test item concentrations.The following results were obtained: ELR50 (24 h): 572.9 mg/l (95%-CI: 470.2 – 726.3 mg/l) and ELR50 (48 h): 185.9 (95%-CI: n.d.).

Description of key information

The Daphnia magna acute immobilisation test was performed with five loading rates between 50 mg/L and 800 mg/L. Because of the low solubility of the test item, resulting in a very low recovery rate, all results are given in relation to the nominal test item concentrations.The following results were obtained: ELR50 (24 h): 572.9 mg/l (95%-CI: 470.2 – 726.3 mg/l) and ELR50 (48 h): 185.9 (95%-CI: n.d.).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

185.9 mg/L