Reaction mass of stigmast-5-en-3-β-ol and stigmasta-5,22-dien-3-β-ol and (24R)-ergost-5-en-3β-ol

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Report date:

2022

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of (24R)-ergost-5-en-3β-ol and stigmast-5-en-3-β-ol and stigmasta-5,22-dien-3-β-ol

EC Number:

904-790-6

Molecular formula:

C28H48O; C29H50O; C29H48O

IUPAC Name:

Reaction mass of (24R)-ergost-5-en-3β-ol and stigmast-5-en-3-β-ol and stigmasta-5,22-dien-3-β-ol

Sampling and analysis

Analytical monitoring:

no

Test solutions

Details on test solutions:

The test concentrations were chosen based on the results of a no GLP test.
A limit test at nominal concentration of 100.0 mg test item/L was performed.
A negative control with algal growth medium only was also tested.

At the test start a stock solution of 100.0 mg test item/L was prepared by direct weighing into
algal growth medium (0.0500 g of test item into 500 mL of reconstituted water).

Test organisms

Test organisms (species):

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

Details on test organisms:

The study was performed with the unicellular, fresh-water green algae Pseudokirchneriella
subcapitata strain (formerly known as Selenastrum capricornutum), cultured in the
laboratories of the Test Facility and originally purchased from the Institute of Plant
Physiology of the University of Göttingen, Germany.
The algae were cultured in a climatic chamber at 24 ± 2°C under continuous uniform
illumination in the range 4440-8880 Lux in the spectral range 400-700 nm. The culture
medium was the same of the test medium; the stock cultures were weekly transferred to
fresh medium and maintained in continuous shaking to ensure the necessary amount of CO2
and to keep algae in suspension. Cultures containing deformed or abnormal cells were
discarded.
Only exponentially growing algal cultures have been used to start the test.

Study design

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

The percent inhibition of end-points growth rate and yield at 24, 48
and 72 hours of exposure compared to the negative control. Cell density was measured every 24 hours.
Microscopic observation was also be performed to verify a normal and healthy appearance of
the inoculum culture and to observe any abnormal appearance of the algae (as may be
caused by the exposure to the test substance) at the end of the test.
No remarkable observations were made concerning the appearance of the cells of the
inoculum culture and of the test item tested concentration.

Test conditions

Test temperature:

23.55 – 24.53°C.

pH:

Test start: 7.91 for negative control and 7.78 for test item solution
Test end: 7.45 for negative control and 7.67 for test item solution
(as mean value between replicates)

Nominal and measured concentrations:

100 mg/l nominal

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

At the end of the test, no growth rate inhibition and no yield inhibition, compared to the negative control, was observed for the nominal test item concentration.