Pregna-1,4-diene-3,20-dione, 6-fluoro-11-hydroxy-16-methyl-21-[(1-oxopentyl)oxy]-, (6.alpha.,11.beta.,16.alpha.)-

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:

03 Apr to 13 Jul 2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

No analytical verification of test item concentrations.

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Remarks:

On customer request the study was conducted without analysis

Vehicle:

no

Remarks:

Auxiliaries: ultrasonic bath, magnetic stirrer and folded filter

Details on test solutions:

Pre-treatment of test item and preparation of test item concentration:
- 1.3 mg of the test item were added to 1 litre of dilution water, treated for 1 h in an ultrasonic bath and stirred for 24 h on a magnetic stirrer
- undissolved particles of the test item were removed by filtration using a folded filter (pore siz: 7-12 μm)
- pH was measured to be 8.7
- 100 mL of the solution were taken and 0.658 mL of the algal inoculum was added to each replicate resulting in a final cell density of 5000 cells/mL

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Source: Strain of the test species obtained from 'The Collection of Algal Cultures' of the Institute of Plant Physiology at the University of Göttingen (Germany)
- Maintenance and Acclimatisation: Exponentially growing stock cultures were maintained under constant temperature conditions (21-24 °C with a maximum fluctuation of +/- 2 °C) at a light intensity in the range 60 to 120 μE x m-2 x s-1 (measured in the range 400 to 700 nm). The growth medium (according to BRINGMANN & KÜHN (1977)) was renewed once a week. Cell density measurements were made using a microcell counter, Sysmex F300, Digitana.
- Preparation of pre cultures: Pre cultures were set up three days before the start of a test. They were grown under identical exposure conditions as the stock cultures, except from the use of a different growth medium.
- Test cultures: The algal inocula for the test were taken from an exponentially growing pre culture and were mixed with the growth medium to make up to a final cell density of about 5000 cells/mL in the test medium.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

1.3 °dH (22.5 mg/L CaCO3)

Test temperature:

21 - 24 °C

pH:

7.9 - 8.4

Salinity:

n.a.

Conductivity:

No data

Nominal and measured concentrations:

Limit test concentration of nominally 1.0 mg/L

Details on test conditions:

Exposure conditions:
- Test vessels: 300 mL Erlenmeyer flasks with cotton stoppers
- Test volume: 100 mL
- Culturing apparatus: Shaking incubator in which a temperature in the range 21 °C to 24 °C was maintained at +/- 2 °C, and continuous uniform illumination was provided in the spectral range 400 to 700 nm. Temperature was measured and recorded daily
- Light intensity: A light intensity ranging from 60 to 120 μE x m-2 x s-1, or an equivalent range of 4000 to 8000 lux, was measured. The light intensity was checked before the start of the study
- Cell density measurements: in a microcell counter (Sysmex F300, Digitana) by taking small aliquots from each test flask, which were not replaced
- Experimental design: 1 test concentration plus 1 control
- Replicates: 6 per concentration, 6 per control
- Initial cell density in the test cultures: approx. 5000 cells/mL
- Test item concentration/s: 1.0 mg/L (nominal)
- Method of administration: direct weighing
- Criteria of effects: test item-induced inhibition of yield [y] and growth rate [r] of the algal population

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

< 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

<= 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

A 30 % effect for growth rate against algae was observed at a limit test concentration of 1.0 mg/L (nominal) under exposure conditions for the substance.

The results are expressed in terms of nominal concentrations. On customer request the study was conducted without analysis and with a limit test concentration of 1.0 mg/L (nominal).

All calculations were carried out using the statistics programme ToxRatPro Version 2.10 (released 2010-09-10). For the calculations all algae counts were divided by a factor of 10000.

 

Validity criteria for the measurement of the toxicity to algae:

Target condition according to guideline:	Actual condition according to the study:	Validity criteria met:
Exponentially growing test organisms are exposed to the test substance in batch cultures over a period of normally 72 hours.	Desmodesmus subspicatus was used as a test organisms. Exponential growth of the algae was confirmed. The test duration was 72 h.	Yes
For the final definitive test at least five concentrations, arranged in a geometric series with a factor not exceeding 3.2, should be selected.	Limit test (one concentration) was carried out.	No
The cultures should be maintained at a temperature in the range of 21 to 24°C, controlled at ± 2°C.	The test temperature was 23 +/- 1°C.	Yes

 

Validity criteria fulfilled:

yes

Remarks:

See "Any other information on results incl. tables".

Conclusions:

The toxicity of Fluocortolon-21-Valerat towards algae was determined in a static test. After 72 hours of exposure NOECr and ErC10 were determined as lower than 1 mg/L and the ErC50 as higher than 1 mg/L, respectively. The results are expressed in terms of nominal concentrations.

Executive summary:

The study was conducted in accordance with Commission Regulation (EC) No 761/2009 amending Regulation No 440/2008, Method C.3 ‘Freshwater Alga and Cyanobacteria, Growth inhibition test’ (2009) which is equivalent to OECD Guideline for Testing of Chemicals No. 201 (2006). Exponentially growing algal cells were exposed for a period of 72 hours to a limit test concentration of nominally 1.0 mg/L of Fluocortolon-21-Valerat dissolved in dilution water. Auxiliaries used to prepare the test media were an ultrasonic bath, a magnetic stirrer and a folded filter. The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. Growth rates were also used to calculate a No Observed Effect Concentration (NOEC) and a Lowest Observed Effect Concentration (LOEC) according to STUDENT-t test for Homogeneous Variances. At a limit test concentration of 1.0 mg/L (nominal) under exposure conditions a thirty percent effect for growth rate against algae was observed. After 72 hours of exposure NOECr and ErC10 were determined as lower than 1 mg/L and the ErC50 as higher than 1 mg/L, respectively. The results are expressed in terms of nominal concentrations. This toxicity study is classified as acceptable and satisfies the guideline requirements for the Algae study.

Description of key information

The toxicity of Fluocortolon-21-Valerat towards algae was determined in a static test according to OECD Guideline 201. After 72 hours of exposure NOECr and ErC10 were determined as lower than 1 mg/L and the ErC50 as higher than 1 mg/L, respectively. The results are expressed in terms of nominal concentrations.

Key value for chemical safety assessment

EC50 for freshwater algae:

1 mg/L

EC10 or NOEC for freshwater algae:

1 mg/L

Additional information

"Should read: 72 h ErC50 >1 mg/L and 72 h NOECr <1 mg/L "

A 30 % effect for growth rate against algae was observed at a limit test concentration of 1.0 mg/L (nominal) under exposure conditions.