ethyl N-acetyl-3,5-dinitro-L-tyrosinate

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2021

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

L-Tyrosine, N-acetyl-3,5-dinitro-, etyhl ester

Cas Number:

29358-99-4

Molecular formula:

C13H15N3O8

IUPAC Name:

L-Tyrosine, N-acetyl-3,5-dinitro-, etyhl ester

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

21.4-22.1 °C

pH:

7.2-7.8

Nominal and measured concentrations:

1 / 3.2 / 10 / 32 / 100 mg/L nominal concentration

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

<= 3.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

yield

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

<= 3.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 3.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

yield

Effect concentrations 4

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 3.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 5

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

19.51 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 6

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

2.14 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

yield

Effect concentrations 7

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

31.99 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

yield

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

One valid experiment was performed.
The study was performed using 5 concentrations ranging from 1 to 100 mg/L (nominal). Incubation time (test system Desmodesmus subspicatus) was 72 hours. The cell concen-tration of each replicate was determined by measuring the cell numbers every 24 hours with an electronic particle counter. Growth rate µ and the yield were determined from the cell number at the respective observation times.
Significant inhibition of algal growth was observed in all tested concentrations for growth rate and yield.

At the start and at the end of the test, the content of the test item in the test solutions was determined using HPLC.
The measured concentrations lay between 84 % and 95 % of the nominal concentrations at the beginning of the test and between 91 % and 102 % of the nominal concentrations at the end of the test. Therefore, the determination of the biological results was based on the nominal concentrations (see Guidance Doc. No.23 (§176)).

In the four highest concentrations, a clear dose-response relationship was observed in ac-cordance with the measured concentrations. However, in the lowest concentration 1 mg/l the inhibition was slightly higher than in the concentration 10 mg/L.
The analytical measurements showed that the inhibition in the lowest concentration was not caused by the test substance. Therefore, the lowest concentration was excluded from the evaluation. The consideration of the lowest concentration would falsify the determination of EC10.

The 72h-EC50 values of potassium dichromate (K2Cr2O7, CAS No. 7778-50-9) were deter-mined in a separate reference test. The values lay within the range of the laboratory (growth rate 0.65 - 1.10 mg/L, yield 0.21 – 0.66 mg/L).

The pH of the blank control should not fluctuate by more than 1.5 units. The change was 0.1 units in the blank control.

All validity criteria were met.
No observations were made which might cause doubts concerning the validity of the study outcome. The result of the test can be considered valid.

Executive summary:

One valid experiment was performed.

The study was performed using 5 concentrations ranging from 1 to 100 mg/L (nominal). Incubation time (test system Desmodesmus subspicatus) was 72 hours. The cell concentration of each replicate was determined by measuring the cell numbers every 24 hours with an electronic particle counter. Growth rate µ and the yield[1] were determined from the cell number at the respective observation times.

Significant inhibition of algal growth was observed in all tested concentrations for growth rate and yield.

 

At the start and at the end of the test, the content of the test item in the test solutions was determined using HPLC.

The measured concentrations lay between 84 % and 95 % of the nominal concentrations at the beginning of the test and between 91 % and 102 % of the nominal concentrations at the end of the test. Therefore, the determination of the biological results was based on the nominal concentrations (see Guidance Doc. No.23 (§176)).

 

In the four highest concentrations, a clear dose-response relationship was observed in accordance with the measured concentrations. However, in the lowest concentration 1 mg/l the inhibition was slightly higher than in the concentration 10 mg/L.

The analytical measurements showed that the inhibition in the lowest concentration was not caused by the test substance. Therefore, the lowest concentration was excluded from the evaluation. The consideration of the lowest concentration would falsify the determination of EC₁₀.

 

The 72h-EC₅₀ values of potassium dichromate (K₂Cr₂O₇, CAS No. 7778-50-9) were determined in a separate reference test. The values lay within the range of the laboratory (growth rate 0.65 - 1.10 mg/L, yield 0.21 – 0.66 mg/L).

 

 

 

The following results for the test item L-Tyrosine, N-acetyl-3,5-dinitro-, ethyl ester were determined:

Table 3             Results of the test item

Endpoint	NOEC	LOEC	EC10	EC50
Growth Rate	< 3.2 mg/L	≤ 3.2 mg/L	19.51mg/L	n. d.
Yield	< 3.2 mg/L	≤ 3.2 mg/L	2.14 mg/L	31.99 mg/L

n. d. = not determinable due to mathematical reasons or inappropriate data

 

Note: According to the guideline, NOEC is determined by comparing of the respective treatment with the blank control. Statistically insignificant variation is considered as “no observed effect”, although the EC₁₀ which is read from the graph toxicity vs. concentration may lie lower.

 

[1] Yield (according to OECD Guideline 201) is defined as the biomass at the end of the exposure period minus the biomass at the start of the exposure period. Calculation see under 8.2 Growth and growth inhibition are quantified from measurements of the algal biomass as a function of time. Algal biomass is defined as the dry weight per volume, e.g. mg algae/L test solution. However, dry weight is difficult to measure and therefore surrogate parameters are used. Of these surrogates, cell counts are most often used.