L-aspartic acid, sodium salt

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

23 March 2006

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

sodium 2-amino-3-carboxypropanoate

Cas Number:

323194-76-9

Molecular formula:

C4H7NO4.xNa

IUPAC Name:

sodium 2-amino-3-carboxypropanoate

Test material form:

solid: particulate/powder

Details on test material:

Name: L-aspartic acid, sodium salt monohydrate 1
Batch/Lot number: Z201125/ VG29848563
CAS number: 323194-76-9
Anhydrous substance name: L-aspartic acid, sodium salt, CAS: 17090-93-6
Appearance: Solid, white, crystalline powder
Purity: 98%
Expiry date: 24 November 2022
Storage conditions: Room temperature (15-25 ºC), protected from humidity (tight closed
container)

Specific details on test material used for the study:

Information supplied by the Sponsor:

Name: L-aspartic acid sodium salt monohydrate
Lot number: Z201125 / VG29848563
CAS number: 323194-76-9
Description: Solid, crystalline powder, white
Expiry date: 24 November 2022
Purity: min. 98 %
Storage conditions: Room temperature (15-25ºC, below 70% relative humidity)
Safety precautions: Routine safety precautions (lab coat, gloves, safety glasses, face mask) for unknown materials will be applied to assure personnel health and safety.

The certificate of analysis is presented in Appendix 3.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

For determination of the test item concentration, samples were taken from the test solutions and the controls at the start, at 24, 48 hours
and at the end of the experiment. Samples were transferred immediately after collection for
concentration measurement to the Test Facility.
The concentration analyses were conducted under the control of the Analyst, based on the analytical
method validation and in compliance with the relevant SOPs of the Test Facility. The results are
included in the Study Report as Appendix 2.

Test solutions

Vehicle:

no

Details on test solutions:

The stock solution was prepared just before inoculation with the algae (start of the experiment) by dissolving 0.0702g of test material in 700 mL OECD medium. The test solutions were prepared by diluting the stock solution.

Test organisms

Test organisms (species):

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

Details on test organisms:

Raphidocelis subcapitata

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Test temperature:

22 +-1 °C.

pH:

The pH was measured in the control and in the highest test concentration at the start and in each of these test vessels at the end of the experiment. The pH varied by not more than 1.5 units of the controls.

Details on test conditions:

The vessels were held for the duration of the study in a climate chamber, the test temperature was measured continuously with a min/max thermometer and remained between 21.3 and 22.8 °C. The pH was measured in the control and in the highest test concentration at the start and in each of these test vessels at the end of the experiment. The pH varied by not more than 1.5 units of the controls.
Illumination: fluorescent lamps were used with continuous lighting with light intensity of
6941 – 8128 lux.

Reference substance (positive control):

yes

Remarks:

For the evaluation of the quality of the algal cultures and the experimental conditions, potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions.

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC100

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

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

Details on results:

In the 72-h algal growth inhibition test on Raphidocelis subcapitata, the 72-h EC50 value based on growth rate was determined to be higher than 100 mg/L and based on yield was calculated to be higher than 100 mg/L. The NOEC related to growth rates was determined to be 100 mg/L and related to yield it was determined to be 100 mg/L.
The results are based on the nominal concentration.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

In the 72-h algal growth inhibition test on Raphidocelis subcapitata, the 72-h EC50 value based on growth rate was determined to be higher than 100 mg/L and based on yield was calculated to be higher than 100 mg/L. The NOEC related to growth rates was determined to be 100 mg/L and related to yield it was determined to be 100 mg/L.
The results are based on the nominal concentration.

Executive summary:

The purpose of this study was to determine the effect of the test item on the growth of a unicellular green algal species Raphidocelis subcapitata. Exponentially growing cultures of Raphidocelis subcapitata were exposed to the test item over several generations under defined conditions.

 

As slight inhibition was seen in the highest concentration in the preliminary study, a full test with 5 test concentrations was carried out in the main test. The test design included three replicates of the test concentrations and six replicates for the untreated control.

 

As the test item was expected not to be stable for 72 hours, analytical measurements were carried out daily. However the concentration decreased, the final values were over 80% of the start concentration in the higher doses. As all the EC values are over the highest dose, all biological results are based on nominal concentrations.

 

The initial biomass in the test cultures was set to 10⁴ cells/mL.

Glass flasks with total capacity of ~250 mL were used as test vessels. The volume of the test liquid in the vessels was 100 mL. The test vessels were covered with air-permeable stoppers.

 

 

Table 1. Summary of Biological Endpoints

Parameter	Growth rate (r) [mg/L]	Yield (y) [mg/L]
72-h EC50	>100	>100
72-h EC100	>100	>100
72-h NOEC	100	100

 

 

 

Conclusion:   In the 72-h algal growth inhibition test on Raphidocelis subcapitata, the 72-h EC₅₀ value based on growth rate was determined to be higher than 100 mg/L and based on yield was calculated to be higher than 100 mg/L. The NOEC related to growth rates was determined to be 100 mg/L and related to yield it was determined to be 100 mg/L.

The results are based on the nominal concentration.