Linseed oil, ester with pentaerythritol

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From October 30, 2017 to December 21, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Deviations:

yes

Remarks:

Deviations are very minor and doesn’t have any impact on study outcome.

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

yes

Remarks:

Deviations are very minor and doesn’t have any impact on study outcome.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

At the start and at the end of each experiment

Vehicle:

yes

Remarks:

water-accommodated fractions

Details on test solutions:

Test solutions preparation: Before each experiment, the water-accommodated fractions (WAF) of the concentrations to be tested were prepared. In experiment I and II, this was done by weighing the nominal load, adding the appropriate amount of algal medium (demineralised water enriched with minerals but without algae) and stirring for 7 d. During stirring the solutions become turbid (second experiment: only the highest concentrated treatment). Therefore, the resulting turbid solutions were filtrated through 0.45 μm nylon filters. These solutions were used for preparation of the treatments. In experiment III, the nominal load was weighted, the appropriate amount of demineralized water was added followed by stirring for 7 d. To the stock solutions for algal medium
the lower aqueous phase was added. These solutions were used for preparation of the treatments.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

- Source: MBM Sciencebridge GmbH (Institut für Pflanzenphysiologie of Universität Göttingen).
- The algae are kept as stock culture on solid agar at 2 - 8 °C..

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

20.5 - 22.8°C

pH:

7.1 - 8.3

Nominal and measured concentrations:

0.1, 0.32, 1, 3.2 g/L (experiment I) (nominal), 30.03, 25.60, 20.72 and 42.17 mg/L (measured)
1, 3.2, 10, 32, 100 mg/L (experiment II) (nominal), -0.07, -0.07, 0.21, -0.07 and 1.87 mg/L (measured)
0.1, 0.32, 1, 3.2, 10 g/L (experiment III) (nominal), 0.00, 0.00, 0.19, 1.77 and 39.48 mg/L (measured)

Details on test conditions:

Treatments tested:
0.1, 0.32, 1, 3.2 g/L (experiment I) (nominal), 30.03, 25.60, 20.72 and 42.17 mg/L (measured)
1, 3.2, 10, 32, 100 mg/L (experiment II) (nominal), -0.07, -0.07, 0.21, -0.07 and 1.87 mg/L (measured)
0.1, 0.32, 1, 3.2, 10 g/L (experiment III) (nominal), 0.00, 0.00, 0.19, 1.77 and 39.48 mg/L (measured)

The concentrations to be tested were based on non GLP pre-tests.

In experiment I membrane filtration of the turbid solution at the concentration 10 g/L was not possible. Therefore, this treatment was not tested.

Number of replicates:

6 replicates for the blank control
3 replicates for each treatment

Vessels: glass flasks, total volume 65 mL

Duration: 72 hours

Lighting: 5000 lux

Temperature:
20.5 – 22.6 °C (experiment I)
21.3 – 22.6 °C (experiment II)
21.5 – 22.8 °C (experiment III)
Replicates (Blank control): 45 ±1 mL algal medium and algae
Replicates (Treatments): 45 ±1 mL test solution and algae

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 96 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 19 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 0.9 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.9 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Results with reference substance (positive control):

The 72h-EC50 values of potassium dichromate (K2Cr2O7) were determined in a separate reference test. The values lay within the range of the laboratory (growth rate 0.73 - 1.10 mg/L, yield 0.21 – 0.66 mg/L).

Inhibition values (experiment I):

Nominal concentration in g/L	% Inhibition
	Growth Rate (0-72h)	Yield (0-72h)
Blank control	0	0
0.1	42.56	82.11
0.32	42.73	82.24
1	42.67	85.82
3.2	48.02	86.07

Inhibition values (experiment II):

Nominal concentration in mg/L	% Inhibition
	Growth Rate (0-72h)	Yield (0-72h)
Blank control	0	0
1	-7.17	-31.44
3.2	-9.58	-44.17
10	-9.18	-42.34
32	-1.4	-6.56
100	-5.17	-21.73

Inhibition values (experiment III):

Nominal concentration in mg/L	% Inhibition
	Growth Rate (0-72h)	Yield (0-72h)
Blank control	0	0
0.1	-1.38	-4.75
0.32	0.92	2.8
1	10.36	32.07
3.2	9.86	31.15
10	43.82	81.76

Biological results of the test substance (based on experiment III):

Parameter	Value	95% confidence interval
NOEC (Growth Rate) 72 h	0.9 mg/L	`--
NOEC (Yield) 72 h	0.9 mg/L	`--
LOEC (Growth Rate) 72 h	5.2 mg/L	`--
LOEC (Yield) 72 h	5.2 mg/L	`--
72h ErC10	11 mg/L	6.2 mg/L – 21 mg/L
72h EyC10	1.9 mg/L	0.5 mg/L – 7.3 mg/L
72h ErC50	96 mg/L	41 mg/L – 218 mg/L
72h EyC50	19 mg/L	4.1 mg/L – 89 mg/L

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions, the 72 h EC50 in Desmodesmus subspicatus was determined to be 96 mg/L and 19 mg/L (measured) for growth rate and biomass respectively.

Executive summary:

A study was conducted to determine the short term toxicity of the test substance to aquatic algae and cyanobacteria according OECD Guideline 201, in compliance with GLP. Desmodesmus subspicatus was exposed to the different concentrations of WAF of the test substance under static conditions. Three valid experiments were performed. The first experiment was performed using 5 nominal concentrations ranging from 0.1 to 10 g/L. Strong inhibition of algal growth was observed in all treatments. Therefore, a second experiment was performed using lower concentrations. The second experiment was performed using 5 concentrations between 1 – 100 mg/L. In this experiment, no inhibition was observed in any treatment. The measured test substance concentration and the inhibition at the concentration 100 mg/L in both experiments were inconsistent. In both experiments the water-accommodated fractions (WAFs) were prepared by stirring the nominal loads of test substance in algal medium (demineralised water enriched with minerals but without algae) for 7 d. The lower aqueous phase was used for preparation of the treatments. During stirring of the solutions of test substance in algal test medium, the solutions become turbid (in the second experiment only the highest test concentration 100 mg/L). This might be caused by a reaction between dissolved test substance and the ingredients of the test medium. It cannot be excluded that inhibition of algal growth in the first experiment was caused by a modified composition of the test medium. Therefore, a third experiment was performed. The third experiment was performed using 5 concentrations between 0.1 – 10 g/L. In this experiment, the water-accommodated fractions (WAFs) were prepared by stirring the nominal loads of test substance in demineralised water for 7 d. To the necessary amounts of stock solutions for preparation of algal medium the lower aqueous phase was added. These solutions were used for preparation of the treatments. In this experiment, the solutions were not turbid and significant inhibition of algal growth was observed in the 3 highest concentrated treatments. In this experiment, inhibition was caused by toxicity of the test substance and not by modified composition of the test medium. Therefore, only the result of the third experiment was used for determination of the biological results. At the start and at the end of each test, the content of the test substance in the test solutions was estimated by determination of the dissolved organic carbon (DOC) content in the test solutions. The lowest concentrated treatment was not used for the statistical evaluation, because no test substance was measurable and no inhibition of algal growth was observed in this treatment. In the other treatments the measured concentrations at the beginning were in conformance with the different loading rates. At the end of the test, a strong loss of test substance was observed especially in the lower concentrated treatments. Less inhibition of algal growth results in a higher amount of biomass in the test solution. Certainly, loss of test substance was caused by adsorption or ingestion of dissolved test substance onto the algal cells. That means a part of the test substance was present in the test solution, but not measurable. Therefore, the biological results were based on the measured start concentration. Under the study conditions, the 72 h EC50 in Desmodesmus subspicatus was determined to be 96 mg/L and 19 mg/L (measured) for growth rate and biomass, respectively (Muckle, 2018).

 

Key value for chemical safety assessment

EC50 for freshwater algae:

96 mg/L

EC10 or NOEC for freshwater algae:

0.9 mg/L

Additional information

Linseed oil, ester with pentaerythritol

A study was conducted to determine the short term toxicity of the test substance to aquatic algae and cyanobacteria according OECD Guideline 201, in compliance with GLP. Desmodesmus subspicatus was exposed to the different concentrations of WAF of the test substance under static conditions. Three valid experiments were performed. The first experiment was performed using 5 nominal concentrations ranging from 0.1 to 10 g/L. Strong inhibition of algal growth was observed in all treatments. Therefore, a second experiment was performed using lower concentrations. The second experiment was performed using 5 concentrations between 1 – 100 mg/L. In this experiment, no inhibition was observed in any treatment. The measured test substance concentration and the inhibition at the concentration 100 mg/L in both experiments were inconsistent. In both experiments the water-accommodated fractions (WAFs) were prepared by stirring the nominal loads of test substance in algal medium (demineralised water enriched with minerals but without algae) for 7 d. The lower aqueous phase was used for preparation of the treatments. During stirring of the solutions of test substance in algal test medium, the solutions become turbid (in the second experiment only the highest test concentration 100 mg/L). This might be caused by a reaction between dissolved test substance and the ingredients of the test medium. It cannot be excluded that inhibition of algal growth in the first experiment was caused by a modified composition of the test medium. Therefore, a third experiment was performed. The third experiment was performed using 5 concentrations between 0.1 – 10 g/L. In this experiment, the water-accommodated fractions (WAFs) were prepared by stirring the nominal loads of test substance in demineralised water for 7 d. To the necessary amounts of stock solutions for preparation of algal medium the lower aqueous phase was added. These solutions were used for preparation of the treatments. In this experiment, the solutions were not turbid and significant inhibition of algal growth was observed in the 3 highest concentrated treatments. In this experiment, inhibition was caused by toxicity of the test substance and not by modified composition of the test medium. Therefore, only the result of the third experiment was used for determination of the biological results.At the start and at the end of each test, the content of the test substance in the test solutions was estimated by determination of the dissolved organic carbon (DOC) content in the test solutions. The lowest concentrated treatment was not used for the statistical evaluation, because no test substance was measurable and no inhibition of algal growth was observed in this treatment. In the other treatments the measured concentrations at the beginning were in conformance with the different loading rates. At the end of the test, a strong loss of test substance was observed especially in the lower concentrated treatments. Less inhibition of algal growthresults in a higher amount of biomass in the test solution. Certainly, loss of test substance was caused by adsorption or ingestion of dissolved test substance onto the algal cells. That means a part of the test substance was present in the test solution, but not measurable. Therefore, the biological results were based on the measured start concentration.The NOEC for growth rate and yield were determined to be 0.90 mg/L (measured). Under the study conditions, the 72 h EC50 of the test substance in Desmodesmus subspicatus was determined to be 96 mg/L and 19 mg/L (measured) for growth rate and biomass respectively (Muckle, 2018).