Ethyl L-threoninate

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:

2007.08.21 - 2007.08.24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline for Testing of Chemical No. 201 "Freshwater Alga and Cyanobacteria, Growth Inhibition Test". ISO International Standard 8692 "Water quality - Freshwater algal growth inhibition test with unicellular green algae.

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material: Siegfried Ltd., Switzerland; lot. TSC9153(NN); batch. 0706H016(Siegfried)
Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Melting point: 50-55°C
- Boiling point: 180.7-202.1°C
- Water solubility (under test conditions): > 4,000 g/L (20ºC)
OTHER PROPERTIES (if relevant for this endpoint)
- Results of test for ready biodegradability: 97+/-3% of the ThOD after 28 days

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: -20ºC

Analytical monitoring:

yes

Remarks:

TOC analyses were not carried out in compliance with the GLP principles

Details on sampling:

Concentrations: Subsamples from control (as background determination) and from the test concentrations 500 mg/L, 1,000 mg/L and 2000 mg/L
- Sampling method: samples taken from flasks with test solution but without algae (blanks) at the initiation and the termination of the test.

Vehicle:

no

Details on test solutions:

Identity and concentration of auxiliary solvent for dispersal: The test substance was disolved in test medium. The test medium was prepared from Millipore water according to ISO 8692 standard.

Test organisms (species):

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

Details on test organisms:

(clone: NIVA, CHL 1). The algae was received from NIVA, Norway and cultured at DHI under the test conditions prior to the start of the
test.

Test type:

other: continuous shaking

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

cell density at beginning of the test and after 24, 48 and 72 ± 2 hours

Hardness:

24 mg CaCO3/L

Test temperature:

23.1 ± 0°C (measured)

pH:

7.9-8.1 (start)
7.6-8.8 (end)

Variation start-end < 1 pH unit

Dissolved oxygen:

no data

Salinity:

NA

Nominal and measured concentrations:

Nominal
concentration Sampling time Theoretical organic carbon content Actually measured organic carbon content
(mg TOC/L) (mg TOC/L)
Control 0 hours 0 <2*
Control 72 hours 0 <2*
500 mg/L 0 hours 245 220
500 mg/L 72 hours 245 231
1,000 mg/L 0 hours 490 427
1,000 mg/L 72 hours 490 444
2,000 mg/L 0 hours 979 919
2,000 mg/L 72 hours 979 847

Details on test conditions:

The algae were incubated for approx. 72 hours under continuous shaking (approx. 120 RPM)

TEST SYSTEM
- Test vessel: The test was performed in glass flasks with wide neck and a total capacity of 250 mL, each containing 100 mL of test solution
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: 100mL
- Aeration: no
- Type of flow-through (e.g. peristaltic or proportional diluter): static
- Renewal rate of test solution (frequency/flow rate): no renewal
- Initial cells density: The cell density was approx. 9,000 cells/mL at test start, measured in the control by use of a Beckman Coulter MultisizerTM 3 Coulter Counter®.
- Control end cells density:
- No. of vessels per concentration (replicates):3
- No. of vessels per control (replicates):6
- No. of vessels per vehicle control (replicates): NA

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
- Culture medium different from test medium: No
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous
- Light intensity and quality:
Constant illumination from a panel of fluorescent light with anintensity of approx. 60-120 μmol × m-2 × sec-1.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
-The cell density was approx. 9,000 cells/mL at test start, measured in the control by use of a Beckman Coulter MultisizerTM 3 Coulter Counter®. The density was measured in the control mixture as in-vivo fluorescence at the beginning of the test and after 24, 48 and 72
± 2 hours of incubation in triplicate test flasks and the six controls. The fluorescence was measured by use of a Turner TD-700 Laboratory Fluorometer.

Reference substance (positive control):

yes

Remarks:

potassium dichromate (K2Cr2O7, Merck 4864, Batch No. K30614564 227)ko½

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 2 000 mg/L

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1 118 mg/L

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

> 2 000 mg/L

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

500 mg/L

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 1 000 mg/L

Basis for effect:

growth rate

Results with reference substance (positive control):

potassium dichromate (K2Cr2O7, Merck 4864, Batch No. K30614564 227)
NOEC EC10 EC50
0.2mg/L 0.34 mg/L(0.27-0.40) 0.80mg/L (0.73-0.86)

Reported statistics and error estimates:

VKI (1999): TOXEDO Ver. 1.5. Program for statistical estimation of EC values,
based on experimental data from ecotoxicological assays.

US-EPA (1989): Short term methods for estimating the chronic toxicity of effluents
and receiving waters to freshwater organisms. Computer program: Dunnett’s
procedure in the analysis of data from short term toxicity tests with aquatic organisms.
US-EPA, Cincinnati, Version 1.1.

no

Validity criteria fulfilled:

yes

Conclusions:

A NOEC = 500 mg/L for the growth rate was determined. EC10 and EC50 were 1,118 mg/L and > 2,000 mg/L, respectively

Executive summary:

The test substance L-TEE was tested according to the OECD 201, which is further specified in the ISO International Standard 8692.

L-TEE was tested at the following nominal concentrations: 0 (control); 20; 50; 100; 200; 500; 1,000 and 2,000 mg/L. The growth of the algae during 72 hours was followed by measuring the fluorescence at the beginning of the test and every 24 hours. In order to verify the actual test concentrations, samples of the test solutions were collected for chemical analysis. The actual test concentrations were verified by analysis of the Total Organic Carbon (TOC) content.

The test results can be summarised as follows:

• The TOC analyses performed on subsamples from the three highest test concentrations at the initiation and termination of the test, respectively, showed a recovery of the test substance in the range of 86-94%. As it is thus demonstrated that the concentration of the test substance was satisfactorily maintained within ± 20% of the nominal value, the obtained results are based on the nominal test concentrations.

• At a concentration of 20-500 mg/L, no effect was observed on the growth rate of Pseudokirchneriella subcapitata. Significant inhibition of the growth of Pseudokirchneriella subcapitata was observed at concentrations from 1,000-2,000 mg/L.

• NOEC for the growth rate was 500 mg/L. EC10 was 1,118 mg/L and EC50 was >2,000 mg/L.

Description of key information

A NOEC = 500  mg/L for the growth rate was determined. EC10 and EC50 were 1,118 mg/L and > 2,000 mg/L, respectively

Key value for chemical safety assessment

EC50 for freshwater algae:

2 000 mg/L

EC10 or NOEC for freshwater algae:

1 188 mg/L