Phosphoric acid C12-alkyl and C18-alkyl esters, potassium salts

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to section 13 for "Read-Across justification".

Reason / purpose for cross-reference:

read-across source

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and yield

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and yield

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and yield

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and yield

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 2012-02-17 to 2012-03-22

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:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Analyses of DOC (dissolved organic carbon) were made by TC/IC (total carbon/inorganic carbon) measurement using the carbon analyser TOC multi N/C 2100 S (Analytik Jena AG). Samples were taken after preparation of the treatments at the start of the test and at the end of the test and were filtrated with membrane filters (pore diameter 0.45 µm). The samples were measured directly. Each sample was measured at least in duplicate.

Vehicle:

no

Details on test solutions:

As solubility lies below 125 mg/L, the water-accommodated fraction (WAF) was prepared for the test. This was done by weighing the nominal load, adding the appropriate amount of deionised water and shaking for 24 hours. After membrane filtration, the solutions were used to prepare the treatments. Since the solutions were diluted by algal pre-culture and nutrient medium, 1.25 times the nominal amount was used in preparation of the WAF.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: unicellular freshwater green algae
- Strain: Chodat
- Source: MBM Sciencebridge GmbH (Institut für Pflanzenphysiologie of Universität Göttingen)
- Method of cultivation: The algae are kept as stock culture on solid agar at 8 °C.

ACCLIMATION
- Acclimation period: a pre-culture was prepared from the stock culture and was incubated for 96 hours.
- Culturing media and conditions: as pre-culture medium the OECD medium, prepared according to OECD 201, was used.
- Any deformed or abnormal cells observed: no

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

26 - 27 °C

pH:

7.1 - 8.1

Nominal and measured concentrations:

One treatment group - 100 mg/L (nominal concentration)
No measured concentration.

Details on test conditions:

TEST SYSTEM
- Test vessel: beakers
- Type: open
- Material, size, headspace, fill volume: glass, 50 mL
- Aeration: no
- Initial cells density: 3.5E+4 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: nutritien medium (a 10-fold concentrated OECD medium) was used to prepare the culture for the test.
- Culture medium different from test medium: 10-fold concentrated version of the culture medium

OTHER TEST CONDITIONS
- Light intensity and quality: 4800 lux

Reference substance (positive control):

yes

Remarks:

Ptassium dichromate K2Cr2O7

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and yield

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and yield

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and yield

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and yield

Details on results:

- Cell numbers: The cell numbers were determined by photometric measurement of optical density at 440 nm. In the control and the treatment group the cell number was increasing during the exposure period.
- Microscopic observations: In the control and in the treatment group normal growth of the algae was observed.

Results with reference substance (positive control):

The followinf biological results for the reference substance were determined:
72h NOEC = 0.25 mg/L
72h LOEC = 0.4 mg/L
72h ErC50 = 1.4 mg/L
72h EyC50 = 0.38 mg/L

Reported statistics and error estimates:

As the differences between the nominal treatment of 100 mg/L and the control were not significant, the NOEC and LOEC were stated as 100 mg/L.

Analytical Determination

The measured DOC-values of the blank controls and the treatment both lay below the limit of quantification, due to the very low solubility in medium. As no quantification of the test item in the treatments was possible, the biological results were based on the nominal concentration.

Validity

The cell concentration in the control should increase by a factor of at least 16 within 72h.The cell concentration increased by a factor of 130.

Mean coefficient of variation of daily growth rates should not be above 35 %. It was 16 %.

Coefficient of variation of average growth rate during the whole test period should be maximum 7 %. It was 4 %.

The validity criteria were fulfiled and the test is considered as valid.

Results

Because on the poor solubility in water, the analytical determinations of the test item showed poor correlation between nominal and measured concentrations. The measured DOC values in the test solution and in the control were below the limit of quantification. Therefore, the determination of the results was based on the nominal concentration.

The following effects of the test item on the test system were observed under the conditions reported (nominal concentration 100 mg/L, 72 h exposition, 26 - 27 °C): A NOEC of >=100 mg/L and, therefore, no LOEC were observed for all three endpoints. The endpoints biomass integral, growth rate and yield showed inhibitions below 50 % in this study, therefore, the respective ECs lie above 100 mg/L. No observations were made which might cause doubts concerning the validity of the study outcome. The result of the test can be considered valid.

Table 1. Inhibition Values of Single Replicates

Concentration (mg/L)	Replicate	Inhibition Growth Rate µ	Inhibition Area under the Curve AUC	Inhibition Yield
0	1	1.81	9.98	9.92
0	2	-6.81	-25.44	-37.24
0	3	1.63	7.98	9.15
0	4	3.26	9.48	16.11
0	5	-2.60	-8.98	-11.73
0	6	2.70	6.98	13.79
0	Mean	0!	0!	0!
0	SD	3.92	14.35	20.77
100	1	1.12	6.48	6.83
100	2	-0.75	-2.74	-2.06
100	3	3.93	9.23	18.81
100	4	2.98	14.71	14.95
100	5	-2.45	-9.98	-10.95
100	6	1.12	4.99	6.83
100	Mean	0.99	3.78	5.73
100	SD	2.35	8.83	10.93

Validity criteria fulfilled:

yes

Conclusions:

The growth inhibition of the test item on unicellular green algae was determined after 72 hours exposure. The EC10 and EC50 based on the growth rate were determined to be >100 mg/L. As no significant difference between the control and the treatment group was observed, the NOEC and LOEC were stated to be 100 mg/L.

Executive summary:

The acute toxicity of the test item to unicellular green algae Desmodesmus subspicatus was determined according to the OECD Guideline 201 and EU Council Regulation No. 440/2008 method C.3. A static test was performed as a limit test with a concentration of 100 mg/L. The test item solution was prepared as water-accomodation fraction (WAF) solution. The test item was dissolved in nutrition solution - 10 -fold concentrated OECD medium. Pre-cultured algae were exposed to the test concentration and the control, respectively, for 72 hours. Analyses of dissolved organic carbon (DOC) were made by TC/IC measurement usind carbon analyser.The measured DOC-values of the blank controls and the treatment both lay below the limit of quantification due to the very low solubility in medium, threfore, the biological results were based on the nominal concentrations. No abnormal appeareance and shape of the cells was observed in the treatment and the control group. The growth rate of the control and the treatment groups was significantly not different. Therefore, the NOEC and LOEC were stated as 100 mg/L. The EC10 and EC50 based on growth rate and yield corresponded to the nominal concentration >100 mg/L.

Description of key information

Based on a read-across approach, the toxicity to unicellular green algae as EC10 and EC50 based on growth rate was determined to be >100 mg/L and the NOEC to be 100 mg/L, respectively.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

100 mg/L

Additional information

No data on the substance itself is available. The test substance is a mixture of C12 and C18 chain phosphoric acid esters. Therefore, read-across approach to the C18 phosphoric acid ester was applied. A read-across study assessing the toxicity to aquatic algae of 1-Octanol, phosphate, potassium salt (CAS 68987-29-1) is available. This study was used to address the endpoint "Toxicity to aquatic algae and cyanobacteria".

The acute toxicity of CAS 68987-29-1 to unicellular green algae Desmodesmus subspicatus was determined according to the OECD Guideline 201 and EU Council Regulation No. 440/2008 method C.3. A static test was performed as a limit test with a concentration of 100 mg/L. The test item solution was prepared as water-accomodation fraction (WAF) solution. The test item was dissolved in nutrition solution - 10 -fold concentrated OECD medium. Pre-cultured algae were exposed to the test concentration and the control, respectively, for 72 hours. Analyses of dissolved organic carbon (DOC) were made by TC/IC measurement usind carbon analyser.The measured DOC-values of the blank controls and the treatment both lay below the limit of quantification due to the very low solubility in medium, threfore, the biological results were based on the nominal concentrations. No abnormal appeareance and shape of the cells was observed in the treatment and the control group. The growth rate of the control and the treatment groups was significantly not different. Therefore, the NOEC and LOEC were stated as 100 mg/L. The EC10 and EC50 based on growth rate and yield corresponded to the nominal concentration >100 mg/L.

In conclusion, the test substance is expected to have the same effect on aquatic algae, therefore, the EC10 and EC50 of the test substance are considered to be >100 mg/L and the NOEC and LOEC to be 100 mg/L.