Hydrocotyle asiatica, ext.

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:

2019

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

other: EU C.3: „Freshwater Alga and Cyanobacteria, Growth Inhibition Test“

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

For determination of the test item concentrations, samples were taken from the test item treated groups and control at the start and end of the test.

Vehicle:

no

Details on test solutions:

OECD medium, prepared in the laboratory

Test organisms (species):

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

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

21 24 °C controlled at +/- 2 °C

pH:

8 +/- 1

Nominal and measured concentrations:

The following nominal concentrations were tested: 6.25, 12.5, 25.0, 50.0 and 100.0 mg/L.

Reference substance (positive control):

yes

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

12.74 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

6.04 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yeld

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

6.25 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.:

6.25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yeld

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

34.29 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.:

15.85 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yeld

Results with reference substance (positive control):

Potassium dichromate:
72h ErC50: 0.80 mg/L, (95 % confidence limits: 0.49 – 1.49 mg/L)
72h EyC50: 0.50 mg/L, (95 % confidence limits: 0.39 – 0.63 mg/L)

Reported statistics and error estimates:

For the determination of the NOEC, Jonckheere-Terpstra Test (α=0.05), and for determination of the ECx (based on growth rate and yield) values Probit analysis was used.

Validity criteria fulfilled:

yes

Conclusions:

In this study, the EC50 values were 34.29 mg/L/72h and 15.85 mg/L/72h for growth rate and yeld, respectively. The NOECs were 6.25 mg/L/72h and 6.25 mg//72hL for growth rate and yeld, respectively.
The study was regarded as “reliable with restriction” (Klimish score 2), because the toxicity values were determined on the basis of the analytical measurement of the main components Madecassicoside and of the Asiaticoside, that are expected to be hydrolytically instable (see hydrolysis study).

Description of key information

In the study with Raphidocelis subcapitata the EC50 values were 34.29 mg/L/72h and 15.85 mg/L/72h for growth rate and yeld, respectively. The NOECs were 6.25 mg/L/72h and 6.25 mg//72hL for growth rate and yeld, respectively.

The study was regarded as “ reliable with restriction” (Klimish score 2), because the toxicity values were determined on the basis of the analytical measurement of the main components Madecassicoside and of the Asiaticoside, that are expected to be hydrolytically instable (see hydrolysis study).

Key value for chemical safety assessment

EC50 for freshwater algae:

15.85 mg/L

EC10 or NOEC for freshwater algae:

6.25 mg/L