3-acetylthiazolidine-4-carboxylic acid

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:

2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

not specified

Vehicle:

yes

Details on test solutions:

All solutions were sterilized before use.
Composition of the Solutions:
6.4.1 Stock Solution I
NH4Cl 1500 mg
MgCl2*6H2O 1200 mg
CaCl2*2H2O 1800 mg
MgSO4*7H2O 1500 mg
KH2PO4 160 mg
H2O deionised ad 1000 mL
6.4.2 Stock Solution II
FeCl3*6H2O 64 mg
Na2EDTA*2H2O 100 mg
H2O deionised ad 1000 mL
6.4.3 Stock Solution III
H3BO3 185 mg
MnCl2*4H2O 415 mg
ZnCl2 3 mg
CoCl2*6H2O 1.5 mg
CuCl2*2H2O 0.01 mg
Na2MoO4*2H2O 7 mg
H2O deionised ad 1000 mL
6.4.4 Stock Solution IV
NaHCO3 50 g
H2O deionised ad 1000 mL
6.4.5 Algal medium (OECD TG 201)
Stock solution I 10.0 mL
Stock solution II 1.0 mL
Stock solution III 1.0 mL
Stock solution IV 1.0 mL
H2O deionised ad 1000 mL

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Unicellular freshwater green alga.
Genus Desmodesmus
Species subspicatus
SAG Strain Number 86.81
Taxonomic position Chlorophyta - Chlorophyceae

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21.5 – 22.5 °C

Details on test conditions:

Duration: 72 hours
Treatments: 100 / 46 / 22 / 10 / 4.6 mg/L (nominal)
The concentrations to be tested are based on a non GLP pre-test.
Temperature: 21.5 – 22.5 °C
Lighting: within the specified range (4440 – 8880 Lux)
Measurement: cell number via electronic cell counter (Measurement range: 5 – 12 µm)
Replicates
Treatments: 3 vessels, each filled with 45 ±1 mL test solution and algae
1 vessel, filled with 45 ±1 mL test solution without algae for analytical determination

Blank Control: 6 vessels, each filled with 45 ±1 mL algal medium and al-gae
1 vessel filled with 45 ±1 mL algal medium without algae for analytical determination

Reference substance (positive control):

yes

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

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

78.43 mg/L

95% CI:

> 40.98 - < 150.11

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

46 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

46 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Calculation of results was performed with the help of a validated software (Microsoft Ex-cel®). The estimation of the biological data was accomplished using the software ToxRat® Professional, version 3.3.0. The details of calculation are stated in Annex 5: Statistical cal-culation using ToxRat® Professional 3.3.0.
The following values were determined.
Table 10 Biological Results of the Test Item

Parameter	Value	95 % confidence interval
NOEC (Growth Rate) 72 h	46.00 mg/L	--
NOEC (Yield) 72 h	46.00 mg/L	--
LOEC (Growth Rate) 72 h	100.00 mg/L	--
LOEC (Yield) 72 h	100.00 mg/L	--
72h ErC10	> 100.00 mg/L*	--
72h EyC10	78.43 mg/L	40.98 – 150.11 mg/L
72h ErC50	> 100.00 mg/L	--
72h EyC50	> 100.00 mg/L	--

Due to the low inhibition values, the EC50 was not determined by statistical evaluations, but is stated as higher than the highest tested concentration of 100 mg/L
For the endpoint growth rate, an EC10 of 141.16 mg/L was extrapolated by the program. This value lies far above the highest tested concentration 100 mg/L Therefore for the end-point growth rate the EC10 was reported as the range > 100 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

The study was performed using 5 concentrations ranging from 4.6 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 ± 1 hours with an electronic cell counter. Growth rate µ and the yield were determined from the cell number at the respective observation times.
Slight but statistically significant inhibition of algal growth was observed only at the highest tested concentration of 100 mg/L.
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 101 % and 108 % of the nominal concentrations at the beginning of the test and between 104 % and 117 % of the nominal concentrations at the end of the test. Therefore, the determination of the results was based on the nominal concentration (see Guidance Doc. No.23 (§176)).
Due to the low inhibition values, the EC50 was not determined by statistical evaluations, but is stated as higher than the highest tested concentration of 100 mg/L.
For the growth rate, a value for EC10 of 141.16 mg/L, was extrapolated by the program which was far above the highest concentration tested. The EC10 is therefore also given as higher than 100 mg/L.
The 72h-EC50 values of potassium dichromate were determined in a separate reference test. The values were within the range of the laboratory.
The pH of the blank control should not fluctuate by more than 1.5 units. The change was 0.6 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 4.6 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 ± 1 hours with an electronic cell counter. Growth rate µ and the yield were determined from the cell number at the respective observation times.
Slight but statistically significant inhibition of algal growth was observed only at the highest concentration of 100 mg/L.
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 101 % and 108 % of the nominal concentrations at the beginning of the test and between 104 % and 117 % of the nominal concentrations at the end of the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations (see OECD 201 (§ 39)).
Therefore, the determination of the biological results was based on the nominal concentra-tion (see Guidance Doc. No.23 (§176)).
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 0.64 - 1.10 mg/L, yield 0.21 – 0.66 mg/L).

The following results for the test item 3-acetylthiazolidine-4-carboxylic acid were determined:
Table 3 Results of the test item
Endpoint NOEC LOEC EC10 EC50
Growth Rate 46.00 mg/L 100.00 mg/L >100.00 mg/L >100.00 mg/L
Yield 46.00 mg/L 100.00 mg/L 78.43 mg/L >100.00 mg/L

Note: The NOEC is determined by comparing each treatment with the blank control using a hypothesis test. A statistically insignificant variation is considered as "no observed effect". In contrast, EC10 is determined by regression analysis and read from the toxicity vs. con-centration graph. Due to the low inhibition values, the EC50 was not determined by statisti-cal evaluations, but is stated as higher than the highest tested concentration of 100 mg/L.
For the growth rate, a value for EC10 of 141.16 mg/L, was extrapolated by the program which was far above the highest concentration tested. The EC10 is therefore also given as higher than 100 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

100 mg/L