2-Propenoic acid, methyl ester, reaction products with 2-ethyl-1-hexanamine and sodium hydroxide

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:

experimental study

Adequacy of study:

key study

Study period:

January 30, 2018 - July 16, 2018

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

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Composition of test material: Sodium-2-ethylhexyliminomonopropionate and Sodium-2-ethylhexyliminodipropionate
- Analytical purity: >=99%
- Purity test date: 13 December 2017
- Lot/batch No.: WI6K21X06-FD1
- Expiration date of the lot/batch: 05 December 2018
- Appearance: White paste
- Storage: At room temperature

Analytical monitoring:

yes

Details on sampling:

- Sampling method: At t = 0h and t = 72h from all test concentrations and the control
- Sample storage conditions before analysis: Samples were stored in a freezer (≤-15°C) until analysis

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test item was completely soluble in test medium at the concentrations tested. Preparation of test solutions started with the highest concentration of 112 mg/L in the combined limit range-finding test and 100 mg/L in the final test, applying approximately a 15 minute period of magnetic stirring to accelerate dissolution of the test item in medium. The pH of the stock solutions was adjusted from 9.7 to 8.1 in the combined limit/range-finding test and from 9.5 to 8.2 in the final test with 1 mol HCl/L. Lower test concentrations were prepared by subsequent dilutions of the highest concentration in test medium. All test solutions were clear and colorless at the end of the preparation procedure. After preparation, volumes of 50 mL were added to each replicate of the respective test concentration. Subsequently, 1 mL of an algal suspension was added to each replicate providing a cell density of 104 cells/mL.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name:
- Strain: NIVA CHL 1
- Source (laboratory, culture collection): In-house laboratory culture
- Method of cultivation: Algae stock cultures were started by inoculating growth medium (M1) with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light (60-120 µE/m2/s, 400-700 nm) in a climate room at a temperature of 21-24°C

ACCLIMATION
- Acclimation period: 3-4 days before the start of the test
- Culturing media and conditions: Cells from the algal stock culture were inoculated in culture medium (M2) at a cell density of 10,000 cells/mL. The pre-culture was maintained under the same conditions as used in the test

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21.2-23.5°C

pH:

8.0-8.2

Nominal and measured concentrations:

Nominal test concentrations: control, 0.10, 0.32, 1.0, 3.2 and 10 mg/L (final test)

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL, all-glass vessels
- Type: Closed
- Fill volume: 50 mL of test solution
- Aeration: No
- Renewal of test solution: No (static test)
- Initial cells density: 10,000 cells/mL
- Control end cells density: 868,000 cells/mL (final test, t = 72h)
- No. of vessels per concentration (replicates): 3 (with algae) + 1 (without algae)
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: Yes (M2 medium)

TEST MEDIUM / WATER PARAMETERS
- Dilution water: Milli-RO water
- Culture medium different from test medium: Yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no
- Adjustment of pH: Yes
- Photoperiod: Continuous illumination
- Light intensity and quality: 82-85 µE.m-2.s-1

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: Counting chamber
- Other: At the end of the final test, microscopic observations were performed on the 1.0 mg/L test concentration to observe for any abnormal appearance of the algae

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Range finding study: Yes (control, 0.11, 1.1, 11 and 112 mg/L)

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: based on analytically confirmed nominal concentrations

Remarks:

95% CL 1.7-2.0 mg/L

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.43 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: based on analytically confirmed nominal concentrations

Remarks:

95% CL 0.36-0.50 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: based on analytically confirmed nominal concentrations

Remarks:

based on biological relevance

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.55 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: based on analytically confirmed nominal concentrations

Remarks:

95% CL 0.48-0.64 mg/L

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.18 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: based on analytically confirmed nominal concentrations

Remarks:

95% CL 0.14-0.24 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: based on analytically confirmed nominal concentrations

Remarks:

based on biological relevance

Details on results:

MEASURED CONCENTRATIONS
Samples taken from all test concentrations and the control were analysed. The final test item exposure concentrations were calculated based on the responses of the two constituents separately measured. The measured concentrations for the test item were at the level of nominal (90-110%) throughout the test, based on the responses of both constituents. Based on these results, the effect parameters were based on analytically confirmed nominal concentrations.

INHIBITION OF GROWTH RATE AND INHIBITION OF YIELD
Growth rate and yield were in the range of the control at the lowest test concentration during the 72 hour test period, whereas at higher concentrations growth rate and yield were increasingly inhibited. Statistically significant inhibition of growth rate and yield was found at test concentrations of 0.32 mg/L and higher. The inhibition of growth rate observed at the concentrations of 0.32 mg/L was however, considered biologically not relevant (i.e. was <10%). Therefore, the NOEC based on biological relevance was set at 0.32 mg/L. Microscopic observations at the end of the test revealed a normal and healthy appearance of the algal cells exposed to 1.0 mg/L when compared to the control.

ACCEPTABILITY OF THE TEST
1. In the control, cell density increased by an average factor of at least 16 within the exposure period (i.e. 87).
2. The mean coefficient of variation for section-by-section specific growth rates in the control cultures did not exceed 35% (i.e. 23%).
3. The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures did not exceed 7% (i.e. 1.1%).
The study met the acceptability criteria prescribed by the study plan and was considered valid.

Results with reference substance (positive control):

The EC50 for growth rate inhibition in the reference test with potassium dichromate (72h-ErC50) was 1.6 mg/L with a 95% confidence interval ranging from 1.5 to 1.6 mg/L. The historical ranges for growth rate inhibition lie between 0.82 and 2.3 mg/L. Hence, the 72h-ErC50 for the algal culture tested corresponds with this range.

The EC50 for yield inhibition in the reference test with potassium dichromate (72h-EyC50) was 0.50 mg/L with a 95% confidence interval ranging from 0.48 to 0.52 mg/L. The historical ranges for yield inhibition lie between 0.43 and 1.1 mg/L. Hence, the 72h-EyC50 for the algal culture tested corresponds with this range.

Growth rate and percentage inhibition for the total test period

Test item Nominal conc. (mg/L)	Mean	Std. Dev.	n	%Inhibition
Control	1.487	0.0160	6
0.10	1.499	0.0262	3	-0.77
0.32	1.376	0.0989	3	7.5^#
1.0	1.025	0.0270	3	31*
3.2	0.550	0.0774	3	63*
10	0.009	0.0155	3	99*

* - effect was statistically significant,^#- effect was statistically significant but biologically not relevant (<10%).

Yield and percentage inhibition for the total test period

Test item Nominal conc. (mg/L)	Mean	Std. Dev.	n	%Inhibition
Control	85.8	4.17	6
0.10	88.9	7.22	3	-3.7
0.32	62.8	17.65	3	27*
1.0	20.7	1.78	3	76*
3.2	4.3	1.26	3	95*
10	0.0	0.05	3	100*

* - effect was statistically significant.

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the present study, the test item significantly reduced the growth rate of the freshwater algae Raphidocelis subcapitata at nominally 1.0 mg/L and higher.

The EC50 for growth rate inhibition (72h-ERC50) was 1.9 mg/L with a 95% confidence interval ranging from 1.7 to 2.0 mg/L; the EC10 for growth rate inhibition (72h-ERC10) was 0.43 mg/L with a 95% confidence interval ranging from 0.36 to 0.50 mg/L; the 72h-NOEC for growth rate inhibition was 0.32 mg/L based on biological relevance; he 72h-NOEC for growth rate inhibition was 0.10 mg/L based on statistical significance.

The EC50 for yield inhibition (72h-EYC50) was 0.55 mg/L with a 95% confidence interval ranging from 0.48 to 0.64 mg/L; the EC10 for yield inhibition (72h-EYC10) was 0.18 mg/L with a 95% confidence interval ranging from 0.14 to 0.24 mg/L; the 72h-NOEC for yield inhibition was 0.10 mg/L based on both biological relevance and statistical significance.

Executive summary:

The toxicity of the test item to freshwater green algae Raphidocelis subcapitata was determined in a GLP-compliant study performed in accordance with OECD Guideline No. 201. A 72-hour 50% effective concentration ErC50 of 1.9 mg/L (95% CL 1.7-2.0 mg/L) and a 72-hour 10% effective concentration ErC10 of 0.43 mg/L (95% CL 0.36-0.50 mg/L) were obtained for growth rate inhibition, based on analytically confirmed nominal concentrations.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

12/9/1995 - 15/9/1995

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study, GLP, quality criteria met. no details on test material identity. no analytical measurement of test concentrations.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not relevant

Analytical monitoring:

no

Details on sampling:

Not relevant

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The stock cultures were maintained, and the tests peformed, in deionised water with added nutrients. Before use, the water was sterilised by autoclaving at 120ºC for 15 minutes. Sterile nutrient stock solutions were then added and the pH value adjusted to 8.0 +/- 0.2 to obtain the culture medium.
- Controls: Yes, blanks

Test organisms (species):

Chlorella vulgaris

Details on test organisms:

TEST ORGANISM
- Common name: Chlorella vulgaris
- Strain: CCAP 211/12
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa
- Method of cultivation: at 20 +/- 1ºC, 6000 - 10000 lux continuous white light and 200 rpm shaking.

ACCLIMATION
- Acclimation period: 3-4 days
- Culturing media and conditions (same as test or not): same as test

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

Not relevant

Hardness:

No data

Test temperature:

No data

pH:

7.7 - 9.8

Dissolved oxygen:

No data

Salinity:

Not relevant

Nominal and measured concentrations:

Nominal concentrations: 0, 63, 125, 250, 500 and 1000 mg/l (0, 25.2, 50, 100, 200 and 400 mg/l based on active ingredient).

Details on test conditions:

TEST SYSTEM
- Initial cells density: 0.71 x 10^4 cells/ml
- Control end cells density: 238.8 x 10^4 cells/ml
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: no
- Detailed composition if non-standard medium was used:
NH4Cl: 15 mg/l
MgCl2.6H2O: 12 mg/l
CaCl2.2H2O: 18 mg/l
MgSO4.7H2O: 15 mg/l
KH2PO4: 1.6 mg/l
FeCl3.6H2O: 0.08 mg/l
Na2EDTA.2H2O: 0.1 mg/l
H3BO3: 0.185 mg/l
MnCl2.4H2O: 0.415 mg/l
ZnCl2: 0.003 mg/l
CoCl2.6H2O: 0.0015 mg/l
CuCl2.2H2O: 10^-5 mg/l
Na2MoO4.2H2O: 0.007 mg/l
NaHCO3: 50 mg/l

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionised water
- Culture medium different from test medium: No
- Intervals of water quality measurement: start and end of the test (0 and 72 hours)

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: No
- Photoperiod: Continuous
- Light intensity and quality: white light, 6000 - 10000 lux

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 400 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 400 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes
- Any stimulation of growth found in any treatment: Yes, growth stimulation found in all treatents after 72 hours, except for 1000 mg/l based on growth rate

Results with reference substance (positive control):

Not relevant

Reported statistics and error estimates:

No data

For detailed results, see attached file "Results.docx".

Validity criteria fulfilled:

yes

Remarks:

16-fold increase in cell density in controls, pH increase within acceptable limits except for 63 mg/l treatment (2.1 increase)

Conclusions:

The acute (72h-EC50) toxicity of test item towards Chlorella vulgaris is > 400 mg a.i./l.

Executive summary:

The acute toxicity of test item towards Chlorella vulgaris was investigated according to OECD Guideline 201 under GLP. Algae were exposed to nominal concentrations of 63, 125, 250, 500 and 1000 mg/l (25.2, 50, 100, 200 and 400 mg/l based on active ingredient) for 72 hours and cell densities and biomass were measured. The 72h-EC50 for biomass and growth rate were found to be > 400 mg/l.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study has been performed under GLP according to protocol.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

The NaHCO3 concentration of the test medium was 150 mg/L instead of 50 mg/L, biomass (dw/mL) was not determined at the end of the test in the control vessels, chemical analyses were also performed on parallel test vessels without algae.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

At the start of the test, samples were taken from all test concentrations and the control and stock solution. At the end of the test samples were taken from all parallel concentrations and the parallel control as well as from all actual test vessels at all concentrations. All samples were diluted with leaching solution.

At least 10 mL was sampled in each case this was diluted 1:1 with leaching solution. The samples were then gently shaken and transferred into the analytical vials for analysis. With each transfer step the pipettes used were rinsed with the solution to be analysed and the solution discarded before sampling for the actual analysis.
Samples from the actual test replicates were filtered using a 0.45 µm filter to remove algae. Filters were primed with the relevant solution before use.
Samples taken at the start of the test were stored in the refrigerator until analysis. No stability samples were included because it was seen in the Daphnia reproduction study that sample concentration was stable during storage.

Vehicle:

no

Details on test solutions:

Preparation of the stock solution:
The test substance is readily dissolved in water. A stock solution of 1.010 g/L of test material was prepared in a 100 mL volumetric flask. An accurately measured amount of 0.1010 g of test material, weighed out on an analytical balance, was loaded in 100 mL test medium. The stock solution was then stirred and a clear homogenous solution was obtained.
The pH of the stock solution was checked and found to be 8.9, and was therefore adjusted with 1 M HCl solution to 7.9.
The stock solution was stirred while adequate amounts were taken for test solutions.

Preparation of the test solutions:
The test solutions were prepared by addition of the adequate amounts of stock solution to the test vessels which contained a certain amount of dilution water.
Based on the results of a range finding study which gave no inhibition at 10 mg/L and major inhibition at 100 mg/L the following final nominal test concentrations were prepared: 7.5, 15, 30, 60 and 120 mg/L.
Control vessels containing only test medium were included in the test.
An additional parallel series with the same concentrations but without addition of inoculum were also prepared for chemical analyses. This series was held under the same conditions as the test series.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

The test was carried out with the freshwater unicellular algae P. subcapitata (CCAP 278/4) obtained from the Culture Collection of Algae and Protozoa SAMS Research Services Ltd. Dunstaffnage Marine Laboratory, Dunbeg, Argyll, Scotland. After purchasing this strain was cultured and maintained. Cultures on sloped agar tubes were stored at 4°C in the dark until required. Exponentially growing cultures are maintained at 23 ± 2°C in a temperature-controlled illuminated orbital incubator and are re-cultured under sterile conditions weekly to keep the algae in this phase.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21.5 - 22.1 °C

pH:

8.2 - 8.7

Nominal and measured concentrations:

Nominal: 7.5, 15, 30, 60 and 120 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL Erlenmeyer flasks
- Aeration: no
- Initial cells density: 1E04 cells/mL
- Control end cells density: 1.44E06 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, OECD medium with 150 mg/L CaCO3 instead of 50 mg/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Culture medium was prepared by diluting the stock mineral salts in an appropriate vessel. This medium was sterilized by filter sterilization (0.2 µm).
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continuous light
- Light intensity and quality: 108.7 µmol/m2/s and 106.5 µmol/m2/s at the beginning and end, respectively

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: spectrophotometer

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study
No inhibition at 10 mg/L and major inhibition at 100 mg/L

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 120 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

> 120 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

Analytical results:
The results of measured concentrations in the test series were all above 80% of the nominal concentrations (see Table VIII).
The responses seen in the lowest test concentration sampled at the end of the test was 144% of nominal, which was not as expected. Because the measured concentration of the sample taken at the start of the test was close to nominal this is considered anomalous and it is not taken into account.
As all other test concentrations showed comparable recoveries at the start and the end of the test it can be concluded that the concentrations were stable over a period of 72h.
Also the stock solution used to make the test solutions showed a good recovery of 99%.

Toxicity:
The results reported are based on nominal test substance concentrations. All reported concentrations refer to the test substance as received and are thus not corrected for active ingredient content.
No effect was found on growth rate up to the highest test concentration, therefore NOEC is equal to or greater than 120 mg/L and LOEC is greater than 120 mg/L. The ErC10 and ErC50 could not be determined, subsequently no confidence limits could be calculated.

Results with reference substance (positive control):

The sensitivity of the algae was checked by performing a growth inhibition test with a reference compound (potassium dichromate) and found to be between the set EC50 values of 0.25 to 2.0 mg/L.

Reported statistics and error estimates:

The Lowest Observed Effect Concentration (LOEC) was determined by comparison of the growth at each concentration and the control using threshold values from the William’s test. The No Observed Effect Concentration (NOEC) was derived from the results as the first concentration below the LOEC value, where growth shows no significant inhibition relative to the control values. All computations were performed using the TOXCALC version 5.023 program.

Criteria for chemical analysis:

Parameter	Limit	Measured
Linearity (R^2)	≥0.98	0.9997
Repeatability (CV (%)) at lowest standard	≤ 20	2.6
Repeatability (CV (%)) at highest standard	≤ 20	1.4
Calculated concentrations of calibration standards (% of nominal)	≥ 80and≤120	82.3-101.1^1
System stability (% of nominal)	≤10	≤10^2
Recovery from medium (%)	≥ 70and≤120	99

CV = coefficient of variation

¹One standard deviated more than 20% from the nominal value, therefore this standard was rejected.

²Where deviations were greater than 10 the results were rejected and repeated where possible/necessary.

Validity criteria fulfilled:

yes

Conclusions:

The study was performed according to protocol under GLP and is therefore valid without restrictions (reliability 1). The results can be used for classification and labelling and risk assessment.

Executive summary:

In order to predict effects of chemicals in an aquatic environment, the toxicity to freshwater algae was assessed. The algal toxicity was determined in the Algal Growth Inhibition Test in accordance with OECD, EEC and ISO test guidelines and with the OECD Principles of Good Laboratory Practice.

Slight modifications to the guideline were applied to ensure good growth and pH control of the cultures.

 

The toxicity of Sodium capryliminodipropionate to an exponentially growing culture of P. subcapitata was determined over an exposure period of 72 hours.

No effect was found on growth rate up to the highest test concentration, therefore NOEC is equal to or greater than 120 mg/L and LOEC is greater than 120 mg/L. The E_rC₁₀andE_rC₅₀could not be determined.

The test was conducted in a mineral salts medium in acclimatized illuminated orbital incubator. The maximum variation in pH was 0.5 units.

 

The test is valid as shown by

- the increase of the extinction of the control over 72 h by a factor of 144.

- the mean coefficient of variation for section-by-section specific growth rates in the control cultures is 29%.

- the coefficient of variation of average specific growth rates during the whole test period in the replicate control cultures is 0.4%.    

 

The results of the chemical analyses show that the concentrations in the test solutions at the start and at the end of the test in the test vessels are close to the nominal concentration. All measured concentration stayed within 80 to 120% of the nominal, except for one test sample taken at the end of the test. As the test concentration at the start of the test was close to nominal and there were no effects found up to the highest concentration tested, this was not considered to have an impact on the outcome of the test. Nominal test substance concentrations are used to calculate the effects.

Description of key information

The toxicity of 2-Propenoic acid, methyl ester, reaction products with 2-ethyl-1-hexanamine and sodium hydroxide (methanol free) to freshwater green algaeRaphidocelis subcapitatawas determined in a GLP-compliant study performed in accordance with OECD Guideline No. 201. A 72-hour 50% effective concentration ErC50 of 1.9 mg/L (95% CL 1.7-2.0 mg/L) and a 72-hour 10% effective concentration ErC10 of 0.43 mg/L (95% CL 0.36-0.50 mg/L) were obtained for growth rate inhibition, based on analytically confirmed nominal concentrations.

Key value for chemical safety assessment

EC50 for freshwater algae:

1.9 mg/L

EC10 or NOEC for freshwater algae:

0.43 mg/L

Additional information

The toxicity of 2-Propenoic acid, methyl ester, reaction products with 2-ethyl-1-hexanamine and sodium hydroxide (methanol free) to freshwater green algaeRaphidocelis subcapitatawas investigated in one GLP-compliant study performed in accordance with standard methods, without deviations. The study is considered as reliable (Klimisch 1) and is selected as a key study for the endpoint.

The endpoint study summary for 2-Propenoic acid, methyl ester, reaction products with 2-ethyl-1-hexanamine and sodium hydroxide (methanol free) is linked to study record(s) on the substance itself but also to study record(s) on an analogue substance, a.k.a. Sodium 3-[(2-carboxyethyl)(2-ethylhexyl)amino]propanoate (CAS RN 94441-92-6 / EC 305-318-6). The latter is used as source substance to fill datagaps on 2-Propenoic acid, methyl ester, reaction products with 2-ethyl-1-hexanamine and sodium hydroxide (methanol free) for particular endpoints pertaining to environmental fate, aquatic toxicity and human health toxicity. Several aquatic toxicity data are thus reported for the source substance (e.g.toxicity to aquatic invertebrates, toxicity to aquatic plants – identified as “supporting studies”) to support the read-across approach (cf. read-across justification document attached in "13 Assessment reports").