Estr-4-ene-3,17-dione

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:

2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

not applicable

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Sampling schedule:
- Control: at 72 hours
- Test concentration/s: 0.094 mg/L, 0.21 mg/L, 0.45 mg/L and 1.0 mg/L at 0 and 72 hours

Vehicle:

no

Details on test solutions:

PRETREATMENT OF THE TEST SUBSTANCE:
- 10.1 mg of the test item were added to 1 litre of dilution water and treated for 1 h in an ultrasonic bath and stirred for 24 h on a magnetic stirrer
- The pH was measured to be 7.9
- Appropriate amounts of the stock solution were diluted with dilution water to a volume of 100 mL to produce the different test item concentrations

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST SPECIES:
- 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 maintained in the test facility under constant temperature conditions (21-24 °C with a maximum fluctuation of +/- 2 °C)
- Light intensity: in the range 60 to 120 ¿E x m-2 x s-1 (measured in the range 400 to 700 nm using a spherical quantum flux meter)
- Renewal of the growth medium: once a week
- Cell density measurements: microcell counter, Sysmex F300, Digitana
- Preparation of pre cultures: Pre cultures were set up three days before the start of a test and 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
- Final cell density: about 5000 cells per millilitre in the test medium

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

Final nutrient medium: 1.3 °dH (22.5 mg/L CaCO3)

Test temperature:

21 °C to 24 °C

pH:

After 0 hour: 7.9-8.0
After 72 hours: 8.0-9.7

Dissolved oxygen:

No data

Salinity:

n.a.

Nominal and measured concentrations:

Effective concentrations ranged from 92.5 % to 99.7 % of nominal values at 0 hours, and from 92.1 % to 92.9 % of nominal values at 72 hours

Details on test conditions:

TEST DESIGN

Exposure conditions
- Test vessels : 300 mL Erlenmeyer flasks with cotton stoppers, test volume: 100 mL
- Culturing apparatus: Shaking incubator, temperature in the range 21 °C to 24 °C (+/- 2 °C); continuous uniform illumination in the spectral range 400 to 700 nm; temperature was measured and recorded daily
- Light intensity: 60 to 120 ¿E x m-2 x s-1, or an equivalent range of 4000 to 8000 lux, was measured
- Cell density measurements: measured in a microcell counter (Sysmex F300, Digitana) by taking small aliquots from each test flask, which were not replaced
- Experimental design: 7 test concentrations plus 1 control
- Replicates: 3 per test concentration, 3 replicates per control
- Initial cell density in the test cultures: approx. 5000 cells/mL
- Test item concentration/s: 7 (0.0088, 0.019, 0.043, 0.094, 0.21, 0.45 and 1.0 mg/L)
- Method of administration: stock solution
- Criteria of effects: item-induced inhibition of yield and growth rate of the algal population

Apparatus:
- Analytical balance
- pH meter
- Shaking incubator
- Microcellcounter
- Various glass materials: Erlenmeyer flasks, volumetric flasks, beakers, pipettes

Calculations:
- Statistics programme: ToxRatPro Version 2.10 (released 2010-09-10)
- For the calculations all algae counts were divided by a factor of 10000

Reference substance (positive control):

not required

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.029 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95 % confidence limits: 0.0199-0.0397

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.167 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95 % confidence limits: 0.1419-0.1958

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.019 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.043 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.021 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95 % confidence limits: 0.0177-0.0248 mg/L

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.051 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95 % confidence limits: 0.0469-0.0549 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.019 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.043 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

The results are expressed in terms of nominal concentrations. Effective concentrations ranged from 92.5 % to 99.7 % of nominal values at 0 hours, and from 92.1 % to 92.9 % of nominal values at 72 hours.

The pH value increased by more than 1.5 pH units. This increase is not regarded to be relevant to the results as all validity criteria were met.

Validity criteria fulfilled:

yes

Remarks:

for details see "Overall remarks"

Conclusions:

After 72 hours of exposure NOECr, LOECr, ErC10 and ErC50 were determined as 0.019 mg/L, 0.043 mg/L, 0.029 mg/L and 0.167 mg/L, respectively. All results are expressed in terms of nominal concentrations.

Executive summary:

The toxicity to algae (Desmodesmus subspicatus) was investigated in a static test according to EEC Methods for Determination of Ecotoxicity Annex to Directive 92/69/EEC (O.J. No. L383A, 29.12.92) Part C, Method 3 "Algal inhibition test". Two range finding tests preceded the main test and provided information about the range of concentrations which were used in the main test. In the main test, the algae were exposed to the test item added to dilution water at a range of concentrations for a period of 72 hours. Defined concentrations of the test item led to a certain inhibition of algal yield and growth rate at the end of the 72 hour study period. Cell densities were recorded at 24 hour intervals. The 72 hour EC 10 and EC 50 were calculated by probit analysis. During the test a temperature range of 21 - 24 °C was maintained in the test vessels. The pH was measured at the beginning of the test and after 72 hours of exposure. The maintenance of the test item concentrations was proved by analytical measurements. In order to avoid an impairment of the test system, an additional replicate was used for analysis and pH measurement at the beginning of the test. Chemical analysis and pH measurement at the end of the test were performed using replicate I of the test concentrations and the control vessels.After 72 hours of exposure NOECr, LOECr, ErC10 and ErC50 were determined as 0.019 mg/L, 0.043 mg/L, 0.030 mg/L and 0.167 mg/L, respectively. The results are expressed in terms of nominal concentrations. Effective concentrations ranged from 92.5 % to 99.7 % of nominal values at 0 hours, and from 92.1 % to 92.9 % of nominal values at 72 hours. The validity criteria of the test were met and therefore this toxicity study is classified as acceptable and satisfies the guideline requirements for the Algae study.

Description of key information

The toxicity to algae (Desmodesmus subspicatus) was investigated in a static test according to EEC Methods for Determination of Ecotoxicity Annex to Directive 92/69/EEC (O.J. No. L383A, 29.12.92) Part C, Method 3 "Algal inhibition test". After 72 hours of exposure NOECr, LOECr, ErC10 and ErC50 were determined as 0.019 mg/L, 0.043 mg/L, 0.030 mg/L and 0.167 mg/L, respectively. All results are expressed in terms of nominal concentrations.

Key value for chemical safety assessment

EC50 for freshwater algae:

0.167 mg/L

EC10 or NOEC for freshwater algae:

0.019 mg/L