Prasterone

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:

May - Aug 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: stock solution
- Sampling time: study start

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: For the stock solution 100 mg of prasterone were suspended in 1000 mL demineralized water, ultrasonified for approximately 30 min and constantly stirred for approximately 24 hours at room temperature. Thereafter, the suspension was filtered through a glass-fiber filter (0.2 μm). The pH value was measured in the stock solution. It was pH 8.8.
Since in a preceding test using the undiluted stock solution for preparing the test solutions, the inhibition was more than 99 % at the lowest concentration, a further test was performed in which the filtered solution was 1:100 diluted and then used to prepare the highest test concentration This was 1:1.25 dilution by adding nutrient solution and inoculum. This solution was further diluted 1:5, 1:10, 1:25, 1:50 and 1:100 with demineralized water, nutrient solution (2.5 mL) and inoculum (2.5 mL) for the other concentrations, all by an electronically controlled syringe.
- Eluate:
- Differential loading:
- Controls: yes, test medium control

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Age of inoculum (at test initiation): 72 h
- Source (laboratory, culture collection): "Sammlung von Algenkulturen, Universität Göttingen"
- Method of cultivation: This culture was dissolved in a liquid nutrient solution and subsequently transferred approximately once weekly.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23 - 24 °C

pH:

7.1 - 7.5

Nominal and measured concentrations:

Measured: 0.002, 0.005, 0.01, 0.024, 0.048, 0.192 mg/L

Details on test conditions:

TEST SYSTEM
- Aeration: intermittent stirring
- Initial cells density: 100000 cells per mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: approximately 5200 lux

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: fluoresence every 24 h (wavelength of 320 and 800 nm for agitation and measurement, respectively)
- Other: microscopic examination

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.01 mg/L

95% CI:

>= 0.01 - <= 0.03

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.004 mg/L

95% CI:

>= 0.002 - <= 0.005

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes
- Unusual cell shape: The cells at dilution from 1:10 onwards showed a damage of the membrane.

Validity criteria fulfilled:

yes

Conclusions:

ErC50 (72 h): 0.01 mg/L

Executive summary:

The acute toxicity of Prasterone to alga (Desmodesmus subspicatus) was tested according to OECD guideline 201 'Alga, Growth Inhibition Test' (2006). During 72 hours exposure an ErC50 of 0.01 mg/L was measured.

Description of key information

The acute toxicity of Prasterone to alga (Desmodesmus subspicatus) was tested according to OECD guideline 201 (2006). During 72 hours exposure an ErC50 of 0.01 mg/L was measured.

Key value for chemical safety assessment

EC50 for freshwater algae:

0.01 mg/L

Additional information

should read "< 1 mg/L"