Pregna-1,4,6-triene-3,20-dione, 17-(acetyloxy)-

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:

June 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

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-Acetoxy-1,4,6-pregnatriene-3,20-dione

EC Number:

607-988-8

Cas Number:

2668-75-9

Molecular formula:

C23 H28 O4

IUPAC Name:

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

Sampling and analysis

Analytical monitoring:

yes

Remarks:

TOC

Details on sampling:

- Concentrations: saturated solution
- Sampling method: 0 h

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: For the preparation of the test concentrations 100 mg of ZK 5560 were suspended in 1000 mL demineralized water under constant stirring for 24 hours. Thereafter, the suspension was filtered through a glassfibre filter. The resulted solution was used as the highest test concentration and as the basis for further dilutions 1:2, 1:4, 1:8 and 1:16 with demineralized water.
- 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
- Strain: obtained from the "Sammlung von Algenkulturen, Universität Göttingen"
- Method of cultivation: kept on slant agar containing a nutrient solution at 13 - 18 °C and light/dark rhythm (12h/12h).

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

24 °C

pH:

0 h: 8.2 - 8.3
72 h: 7.8 - 9.4

Nominal and measured concentrations:

nominal: 100, 50, 25, 12.5, 6.25 mg/L
measured saturated solution: 18.2 mg/L
extrapolated to dilutions: 9.1, 4.6, 2.3, 1.1 mg/L

Details on test conditions:

TEST SYSTEM
- Initial cells density: 10000 cells/mL
- Control end cells density: approx. 3825600 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 2

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 and 72 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:

72 h

Dose descriptor:

EC50

Effect conc.:

3.4 mg/L

95% CI:

>= 3.2 - <= 3.5

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.6 mg/L

95% CI:

>= 1.5 - <= 1.7

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Any other information on results incl. tables

Table 1: Inhibition of the growth rate (%) of Scenedesmus subspicatus; after 72 hours exposure to Delta-1,6 -Hydroxyprogesteronacetat

Dilution of ZK 5560	Concentration mg/l	Inhibition in %
		Biomass (integral)	Growth rate
Control	0,0 (control)	0	0
1 : 16	1,1	29	5,3
1 : 8	2,3	68,5	22,2
1 : 4	4,6	95,2	71,2
1 : 2	9,1	98	86,9
Saturated solution	18,2	98,7	88,5

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

ErC50 (72 h): 3.4 mg/L (95% CI: 3.2 - 3.5 mg/L)

Executive summary:

The test substance Delta-1,6-Hydroxyprogesteronacetat was incubated in an aqueous solution including nutrients with an algae population of Scenedesmus subspicatus for a test duration of approximately 72 hours. The nutrient solution was made up of mainly nitrate, phosphates and some trace elements. For the preparation of the test concentrations 100 mg of test substance were suspended in 1000 mL demineralized water under constant stirring for 24 hours. Thereafter, the suspension Was filtered through a glassfibre filter. The resulted solution was used as the highest test concentration and as the basis for further dilutions 1 :2, 1 :4, 1:8 and 1: 16 with demineralized water. A sample of the stock solution was taken directly after preparation for an organic carbon analysis with a TOC analyser. The substance concentration was calculated on the basis of the molecular formula. The concentration was 22.8: mg/L. The further test concentrations were extrapolated from the result of the TOC-analysis and are shown in the table below. The algae were exposed to each concentrationil1 triplicate. Six vessels were prepared for the control. As a parameter for the growth of the algae population, the cell concentrations of the test and control solutions were counted with an electronic particle counter ("Coulter Counter"). The increase of biomass and the growth rate were calculated on the basis of the cell counts. The calculated biomass and growth rate of each concentration were compared to those of the controls, and the inhibition was calculated. The test substance had a clear concentration-related inhibitory effect on the growth of Scenedesmus subspicatus starting at the lowest concentration of 1.1 mg/L. The EbC50 (biomass) was 1.6 mg/L(95% confidence intervals 1.5 - 1.7 mg/L) and the ErC50 (growth rate) was 3.4 mg/L (95% confidence intervals 3.2 - 3.5 mg/l). Accordingly, Delta-Hydroxyprogesteronacetat is toxic to the algae Scenedesmus subspicatus.