Pregna-1,4,6-triene-3,20-dione, 17-hydroxy-

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

Study period:

Jan - Apr 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

17-Hydroxy-1,4,6-pregnatriene-3,20-dione

EC Number:

613-906-1

Cas Number:

66212-25-7

Molecular formula:

C21 H26 O3

IUPAC Name:

17-Hydroxy-1,4,6-pregnatriene-3,20-dione

Test material form:

solid: bulk

Sampling and analysis

Analytical monitoring:

yes

Remarks:

TOC

Details on sampling:

- Concentrations: saturated solution
- Sampling method: Samples were taken after 0 and 96 h.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: For the stock solution 50.1 mg were dissolved in 500 mL demineralized water. This solution was used for the highest test concentration of 4.4 mg/L taking into account the further dilution by introducing the nutrient solution and the algae suspension. To achieve the other test concentrations of 0.04 and 0.4, the solution was diluted 1:100 and 1:10.
- Eluate: no
- Differential loading: no
- Controls: yes, test medium control

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

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

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Test conditions

Test temperature:

24.5 °C

pH:

7.7 - 7.8 start
9.8 - 9.9 end

Nominal and measured concentrations:

nominal: saturated solution, dilutions 1:10, 1:100
measured: 4.4 mg/L mean value

Details on test conditions:

TEST SYSTEM
- Initial cells density: 5000 cells/mL
- Control end cells density: approx. 2120000 cells/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

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Coulter counter after 24, 48, 72 and 96 h

CULTURING APPARATUS
-Details on culturing apparatus used: temperature-controlled shaker

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

> 4.4 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

> 4.4 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Any other information on results incl. tables

Table 1: Inhibition of the growth of Scenedesmus subspicatus after 96 hours exposure to 1,4,6 -Trienol

Dilution	Inhibition in percent
of saturated solution	Biomass (integral)	Growth rate
Control	0	0
1:100	46,9	9,7
1:10	0,5	1,5
Saturated solution	4,7	1,4

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

ErC50 (96 h) > 4.4 mg/L (mean measured, satuated solution)

Executive summary:

The purpose of this study was to determine the effects of the test compound 1,4,6-Trienol on the growth of the green algae Scenedesmus subspicatus. The study was conducted in agreement with the OECD guideline no. 201.

The test substance was incubated in all aqueous solution including nutrients with an algae population of Scenedesmus subspicatus for a test duration of approximately 96 hours. The incubation period was extended to 96 hours, since the cell concentration was initially lower than recommended by the guideline. The nutrient solution was made up of mainly nitrate, phosphates and some trace elements. The algae were incubated in an incubator shaker under continuous light. The test concentrations were a saturated solution and dilutions of 1:10 and 1:100. The algae were exposed to each concentration in triplicates. Six vessels were prepared for the control. The concentration of a saturated solution of 1,4,6 -Trienol was analysed by a TOC analyzer and calculated based on the molecular formula. It was estimated with 4.4 mg/L. 1,4,6-Trienol had no inhibitory effect on the growth of the Scenedesmus subspicatus and thus the study resulted in an EC50 (96 h) > 4.4 mg/L based on growth rate and reproduction.