ethyl N2-dodecanoyl-.sc.l.sc.-argininate hydrochloride

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:

From March 3, 2000 to February 12, 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Guideline study with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

Directive 92/69/EC method C3

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Substance: L.A.E.
Purity: 90%
Batch number: 2625
Expiry date March 14, 2001.

Analytical monitoring:

yes

Details on sampling:

At the start of the definitive test, 2 samples (20 ml) were taken from an additional flask containing the freshly-prepared control and test media; after 72 hours, the contents of the replicate flasks for each group were pooled and further samples taken for analysis. Additional samples were also taken fiom flasks containing dehydrated LAE at 0.0640 and 1.5 mg/l but with no algal cells, in order to obtain information on the extent of adsorption/absorption of the test substance by the algal cells. On each occasion, one sarnple fiom each set was analysed immediately and the other was stored in a fieezer in case further analysis was required.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A concentrated, aqueous stock solution was prepared by adding the test substance (15 mg) to culture medium (90 ml) in a volumetric flask. To aid dissolution, the contents of the flask were treated with ultrasound for ten minutes before being made up to volume (100 ml). This preparation was serially diluted in nutrient medium to give five intermediate stock solutions (0.64, 1.41 ,3.10, 6.82 and 15 mg/L). An aliquot (10 ml) of the appropriate stock solution was then added to each of the test vessels to provide the test media.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Strain: Nº CCAP 278/4
- Source (laboratory, culture collection): Axenic, unicellular, agar slope cultures of algae were obtained from de Culture Collection of Algae and Protozoa, Institue of Freshwater Ecology, Cumbria, UK.
- Method of cultivation: The agar slope cultures were stored in an illuminated refiigerator. Sterile algal nutrient medium was inoculated with cells aseptically removed from the slope culture; these primary liquid cultures (50 ml) were incubated for approximately three days in an orbital incubator under continuous illumination at nominal temperatures in the range 21 to 25 ºC. Subsequently, appropriate volumes of these primary cultures were aseptically transferred to fresh sterile algal nutrient medium to prepare secondary liquid cultures; these cultures were incubated, as stated above, for a fiirther three days to provide an inoculum in the log phase of growth, characterised by a cell density of 1.10 x 10E06 cells/ml. Aliquots of this culture were used in the study.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21.1-23.2 ºC

pH:

7.3-7.8

Nominal and measured concentrations:

Nominal concentrations: 0.0640, 0.141, 0.310, 0682 and 1.5 mg/L.
Measured concentrations (0 hours): nd, 0.0788, 0.243, 0.588 and 1.25 mg/L.

nd: non detected (< 0.0284 mg/L)

Details on test conditions:

TEST SYSTEM
- Test vessel: Conical flask
- Material, size, headspace, fill volume: (250 ml) each containing 100 ml of control or test culture
- Type: closed: loosely plugged with non-absorbent cotton wool
- Initial cells density: 1.10x10E(+6) cells/ml
- No. of vessels per concentration (replicates): Triplicates
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Intervals of water quality measurement: The temperature and pH of control and test flasks at the start and end of the test were recorded.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Light intensity and quality: continous illumination of approximately 8775 lux provided by 4x30W "cool white" 1 metre fluorescent tubes.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: cell densities were measured using a haemacytometer (Improved Neubauer)
- Other: Samples were taken from control and test at 24, 48 and 72 hours.

TEST CONCENTRATIONS
- Range finding study with concentrations: 0.1, 1, 10 and 100 mg/L
- Test concentrations (Nominal): 0.0640, 0141, 0.310, 0682 and 1.5 mg/L

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.461 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95% CL=0.243-0.588

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.723 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL=0.588-1.19

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.243 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

No microscopic abnormalities of the cells were detected.

Reported statistics and error estimates:

EC were calculated by a computer program using percentage effect and test concentrations. (Stephan; 1977, 1982).

Validity criteria fulfilled:

yes

Remarks:

(The cell density in the control culture was increased by a factor > 16 within three days).

Conclusions:

After 72 hours of exposure to dehydrated LAE, the NOEC was 0.243 mg/L and EC50 (growth rate) was 0.723 mg/L.

Executive summary:

The Algal growth test was performed according to OECD 201 and EU method C.3. After 72 hours of exposure to dehydrated N^α-Lauroyl-L-arginine ethyl ester monohydrochloride (L.A.E), the NOEC parameter was 0.243 mg/L and EC50 (growth rate) was 0.723 mg/L.

Description of key information

Test method according to OED 201 and EU method C.3. GLP study. After 72 hours of exposure to dehydrated LAE, the NOEC was 0.243 mg/L and EC50 (growth rate ) 0.723 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

0.723 mg/L

EC10 or NOEC for freshwater algae:

0.243 mg/L