Pregn-4-ene-3,20-dione, 21-(acetyloxy)-6-fluoro-16-methyl-, (6.alpha.,16.alpha.)-

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:

Oct 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to OECD guideline under GLP

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Principles of method if other than guideline:

Not relevant

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

21-Acetoxy-6 alpha-fluoro-16 alpha-methyl-4-pregnene-3,20-dione

EC Number:

603-033-4

Cas Number:

1251-28-1

Molecular formula:

C24 H33 F O4

IUPAC Name:

21-Acetoxy-6 alpha-fluoro-16 alpha-methyl-4-pregnene-3,20-dione

Details on test material:

- Name of test material (as cited in study report): Alpha-FM-DOCA
- Analytical Purity: 71%
- Lot/batch No.: 21602001

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 0.3-1.8 mg/L

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.3 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 72 hours exposure to ZK 4841

Dilution	Concentration	Inhibition in percent
of ZK 46865	(mg/I)	Biomass (integral)	Growth rate
Control	0	0	0
1 :100	0,05	3,8	1,4
1: 50	0,11	-13,9	-5,4
1: 25	0,22	38,4	10,6
1: 13	0,43	68,8	32,5
1: 6	0,87	82,3	49

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

ZK 4841 had an inhibitory, concentration-related effect on the growth of Scenedesmus subspicatus. The EbC50 (biomass) and the ErC50 (growth
rate) were estimated on the basis of the calculated concentrations of ZK 4841 using the organic carbon concentration in the stock
solution. The EbC50 was 0.2 mg/L (no confidence interval could be given), the ErC50 was 1.1 mg/L (95% confidence interval: 0.3-1.8).

Executive summary:

The purpose of this study was to determine the effects of the test compound Alpha-FM-DOCA (ZK 4841) on the growth of the green algae Scenedesmus subspicatus.

The test substance 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 solution, a suspension of 100 mg/I was stirred for 24 hours. This suspension was filtered through a glass fibre filter. The saturated solution obtained by this procedure was used for the highest test concentration. It was further diluted

1:6.3, 1:12.5, 1:25, 1:50 and 1:100. The algae were exposed to each concentration in 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 following table gives the inhibition in percent on the basis of the biomass (integral) and the growth rate.

The measurements showed that there is a decrease in cell concentration over the test period. The resulting growth inhibition was concentration-related.