Decanoic acid, monoester with glycerol

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27 Nov - 1 Dec 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umwelt, Wasserwirtschaft und Gewerbeschutz Rheinland-Pfalz, Mainz, Germany

Test material

Test material information

Constituent 1

Reference substance name:

Esterification product of glycerol and C8-C12 (even numbered) fatty acids

Molecular formula:

not applicable, substance is UVCB

IUPAC Name:

Esterification product of glycerol and C8-C12 (even numbered) fatty acids

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control and all test item concentrations

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The water-accommodated fractions (WAF) of the concentrations to be tested were prepared. This was done by weighing the nominal load, adding the appropriate amount of algal medium (demineralised water enriched with minerals but without algae) and shaking for 24 hours. After membrane filtration (0.45 µm, PTFE-filter), the solutions were used to prepare the treatments.
- Eluate: no
- Differential loading: yes
- Controls: blank control; positive control
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): After filtration, the test solutions were clear.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: freshwater green algae
- Strain: SAG 86.81
- Source (laboratory, culture collection): obtained in January 2016 by MBM Sciencebridge GmbH, Institut für Pflanzenphysiologie of Universität Göttingen, Germany
- Method of cultivation: The algae are kept as stock culture on solid agar at 2 - 8 °C. From the stock culture, a permanent culture was prepared. From an aliquot of the permanent culture, the pre-culture was prepared.

ACCLIMATION
- Acclimation period: 4 days
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: no

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

21.6 – 22.6 °C

pH:

Control: 7.8 - 7.9
Treatments: 7.4 - 7.8

Nominal and measured concentrations:

nominal: 1 / 3.2 / 10 / 32 / 100 mg/L and control
measured: test item not detectable after 72 h

Details on test conditions:

TEST SYSTEM
- Test vessel: glass flasks with a total volume of 65 mL; flasks were covered with perforated plastic foil acting as a stopper
- Aeration: constantly shaken
- Initial cells density: 2.8 *10E+03 cells/mL
- Control end cells density: 3.6 *10E+05 (mean) ± 1.6 *10E+03 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, according to guideline

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline
- Intervals of water quality measurement: pH and temperature measured at test start and end

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continuous light
- Light intensity: 5000 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: The cell concentration of each replicate was determined by measuring the cell numbers every 24 hours with an electronic particle counter. Growth rate µ and the yield were determined from the cell number at the respective observation times. Additionally, the treatments were examined microscopically at the end of the test in order to assess the appearance of the algae and detect abnormalities.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Range finding study: not reported

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

33 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

WAF

Basis for effect:

growth rate

Remarks on result:

other: 95% CI: 7.2 - 142 mg/L

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EL10

Effect conc.:

4.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

WAF

Basis for effect:

growth rate

Remarks on result:

other: 95% CI: 1.2 - 15 mg/L

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

3.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

WAF

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

13 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

WAF

Basis for effect:

other: yield

Remarks on result:

other: 95% CI: 9.5 - 18 mg/L

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EL10

Effect conc.:

7.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

WAF

Basis for effect:

other: yield

Remarks on result:

other: 95% CI: 6.1 - 9.2 mg/L

Effect concentrations 6

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

WAF

Basis for effect:

other: yield

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): Microscopically, cells appeared normal and healthy in the blank control and the three lowest treatments at the end of the test. No cells were visible at the the two highest concentrations.
- For details on biological results, please refer to section "Any other information on results incl. tables"

Results with reference substance (positive control):

- Results with reference substance valid? yes
- The 72h-EC50 values of potassium dichromate were determined in a separate reference test. The values are within the range of the laboratory (growth rate 0.73 - 1.10 mg/L, yield 0.21 – 0.66 mg/L).
- ErC50 (72 h) = 0.94 mg/L (95% CI: 0.90 - 0.98 mg/L)
- EyC50 (72 h) = 0.42 mg/L (95% CI: 0.39 - 0.45 mg/L)

Any other information on results incl. tables

Table 1: Biological results; cell numbers

Nominal Loading Rate in mg/L	Parameter	Cell Number/mL
		0 h	24 h	48 h	72 h
Blank control	Mean	2800	12050	38687	360727
Blank control	SD	0	652	4455	16371
1	Mean	2800	11140	30947	338413
1	SD	0	1512	3685	19816
3.2	Mean	2800	11020	34640	335167
3.2	SD	0	661	1922	21650
10	Mean	2800	11707	32113	257133
10	SD	0	439	806	31787
32	Mean	2800	6487	9693	10433
32	SD	0	948	2017	2005
100	Mean	2800	37887	38840	21660
100	SD	0	8890	6687	1735

Table 2: Inhibition values for growth rate and yield

Nominal Loading Rate in mg/L	% Inhibition
	Growth Rate (0-72h)	Yield (0-72h)
Blank control	0	0
1	1.32	6.23
3.2	1.52	7.14
10	7.06	28.94
32	73.19	97.87
100	57.93	94.73

Table 3: Validity criteria

Criterion from the guideline	Outcome	Validity criterion fulfilled
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.	factor of 129	yes
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%	34%	yes
The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.	1%	yes

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.