N-glycyl-L-tyrosine

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

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)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control and limit concentration

- Sample storage conditions before analysis: samples from the start of the study were stored in freezer until measurement

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: a concentration of 100 mg anhydrous form of test item/L (nominal) was prepared with direct addition of the test item, mixed into the algal growth medium (OECD Medium)
- Controls: OECD Medium
- Test concentration separation factor: limit test
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): no

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Raphidocelis subcapitata
- Strain: 61.81 SAG
- Source (laboratory, culture collection): Collection of Algal Cultures, Inst. Plant Physiology, University of Göttingen, GERMANY

ACCLIMATION
- Culturing media and conditions (same as test or not): same conditions as the test
- Any deformed or abnormal cells observed: no

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

22.6-23.0°C measured in the flask
22.0-23.6°C measured within the climate chamber

pH:

7.29–8.76

Nominal and measured concentrations:

115 mg test item /L (nominal) corresponding to 100 mg N-Glycyl-L-tyrosine/L (calculated as anhydrous form of test item)
As the measured concentration deviated not more than 20 per cent from the nominal during the test, biological results are based on the nominal test item concentration.

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL Erlenmeyer flasks
- Type (delete if not applicable): open
- Aeration: Erlenmeyer flasks were continuously shaken ; flasks were covered with air-permeable stoppers
- Initial cells density: approximately 10000 algal cells per mL test medium
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: flasks were continuously illuminated
- Light intensity and quality: ~ 8162 lux (equivalent to ~110 µE/m2/s)

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


TEST CONCENTRATIONS
- Spacing factor for test concentrations: limit test
- Range finding study: yes
- Test concentrations of Range finding study: 0.1, 1, 10, 100 mg N-Glycyl-L-tyrosine/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

For the evaluation of the quality of the algae and validation of the experimental conditions, potassium dichromate is tested once a year to demonstrate satisfactory test conditions.

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 115 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 115 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 115 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 115 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

yield

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Results with reference substance (positive control):

ErC50 1.01 mg/L
95 % conf. limits 0.81 – 1.26 mg/L

Reported statistics and error estimates:

For determination of the NOEC and the ECx the approaches recommended in the OECD guideline 201 were used. An effect was considered to be significant if statistical analysis of the data obtained for the test concentrations compared with those obtained in the negative control revealed significant inhibition of growth rate or inhibition of yield (William Multiple Sequential t-test, α=0.05, one-sided, smaller). This statistical comparison was preceded by a check on normal distribution of the data (Shapiro-Wilk’s Test) and a test for homogeneity of the variances (Levene’s test).
ToxRat Professional v 3.3.0 (ToxRat Solutions® GmbH, Germany) was used to perform the data analysis.

number of cells - cell concentrations (x 10⁴ cell/mL) during the experiment

Test group	Replicate	0h	24h	48h	72h
Control	1	1	5	18	68
	2	1	4	16	72
	3	1	3	18	67
	4	1	3	20	73
	5	1	4	16	65
	6	1	4	20	73
	Mean	1	3.7	18	69.7
	SD	0	0.8	1.8	3.4
100 mg N-Glycyl-L-tyrosine /L (nominal)	1	1	4	21	73
	2	1	5	17	65
	3	1	4	16	72
	4	1	4	17	70
	5	1	4	20	66
	6	1	3	19	71
	Mean	1	4	18.3	69.5
	SD	0	0.6	2	3.3

 

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the present study with Raphidocelis subcapitata, the test item had no toxic effect on growth rate and yield of this freshwater algae species at the Limit concentration (100 mg N-Glycyl-L-tyrosine/L).

Description of key information

ErC50 (72 h): >100 mg/L (nominal, OECD201)

NOErC (72h): >/= 100 mg/L (nominal, OECD201)

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

100 mg/L