17-acetoxy-1β,2β-methanopegna-4,6-diene-3,20-dione

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

1993

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Remarks:

TOC

Details on sampling:

- Sampling method: 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 and was 3.3 mg/L. The further test concentrations were extrapolated from the result of the TOC-analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF THE TEST SOLUTION
- Methods: for the test solutions, a saturated solution was prepared by adding 125 mg of test substance to 1 L of demineralized water and stirring for 24 h. The solution was then added to the test solution. The filtered solution was used as the highest test concentration and as a base for further dilutions. Dilutions: 1: 10, 1: 100 and 1: 1000 with demineralized water.
- Controls: 1 control, six replicates
- Signs of undissolved material (e.g., precipitate, surface film, etc.): None

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Scenedesmus subspicatus
- Source (laboratory, culture collection): "Sammlung von Algenkulturen, Universität Göttingen"
- Age of inoculum (at test initiation): up to 7 days
- Method of cultivation: slant agar containing a nutrient solution at 13-18°C under light/dark rhythm (12h/12h in diffuse light). This culture was dissolved in a liquid nutrient solution and subsequently transferred approximately on weekly.

ACCLIMATION
- Acclimation period: 3 days

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

281.52 mg CaCO3/L

Test temperature:

24 °C

pH:

8.4 to 9.1 (control)
8.5 to 8.6 (test-solution)

Nominal and measured concentrations:

Measured stock solution concentration (via TOC): 3.3 mg/L; Test concentrations after dilution of the stock solution (extrapolated from measured concentration): 0.003 mg/L, 0.033 mg/L, 0.33 mg/L, 3.3 mg/L

Details on test conditions:

TEST SYSTEM
- Density of the initial cells: 10000 cells/mL
- Final cell density of control: 958000 cells/mL (saturated solution after 72 h)
- Number of vessels per concentration (replicates): 3 replicates per concentration
- Number of vessels per control (replicates): 6 replicates

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- pH setting: 8.5 to 8.6
- Photoperiod: Continuous light

Measured effect parameters (with observation intervals, if applicable) :
- Determination of cell concentrations: electronic particle counter (Coulter Counter)

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 3.3 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 3.3 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria for the measurement of the algae toxicity

Target condition according to guideline:	Actual condition according to the study:	Validity criteria met:
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period. This corresponds to a specific growth rate of 0.92 day^-1. This criterion may not be met when species that grow slower than those listed in Annex 2 of OECD TG 201 are used. In this case, the test period should be extended to obtain at least a 16-fold growth in control cultures, while the growth has to be exponential throughout the test period. The test period may be shortened to at least 48 hours to maintain unlimited, exponential growth during the test as long as the minimum multiplication factor of 16 is reached.	During the test (72 h), biomass in the control increased exponentially by a factor >16.	yes
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%. This criterion applies to the mean value of coefficients of variation calculated for replicate control cultures.	The mean coefficent of variation for section-by-section specific growth rates in the control was 21%.	yes
The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.	The coefficent of variation of average specific growth rates (0-72 h) in the control was 50%.	no
The concentration of the test item shall be maintained to within 80% of the initial concentration throughout the study. The maintenance of concentration is proved by analytical measurements.
The cultures should be maintained at a temperature in the range of 21 to 24 °C, controlled at ± 2 °C.	The cultures were maintained at a temperature of 24 °C.	yes

Conclusions:

The test substance had no inhibitory effect on the growth of Scenedesmus subspicatus up to the measured solubility limit (3.3 mg/L). The EbC50- and ErC50 - values values were > 3.3 mg/L.

Executive summary:

The study was conducted to evaluate adverse effects of the test substance on the growth (=increase in cell density) and growth rate (=increase in cell density with time) of the planktonic freshwater algal species Desmodesmus subspicatus over several generations. The study was conducted in accordance with the OECD Guideline for the Testing of Chemicals No. 201 "Algae, Growth Inhibition Test". The test substance had no inhibitory effect on the growth of Scenedesmus subspicatus up to the measured solubility limit (3.3 mg/L). The EbC50- and ErC50 - values were > 3.3 mg/L.

Description of key information

The study was conducted to evaluate adverse effects of the test substance on the growth (=increase in cell density) and growth rate (=increase in cell density with time) of the planktonic freshwater algal species Desmodesmus subspicatus over several generations. The study was conducted in accordance with the OECD Guideline for the Testing of Chemicals No. 201 "Algae, Growth Inhibition Test". The test substance had no inhibitory effect on the growth of Scenedesmus subspicatus up to the measured solubility limit (3.3 mg/L). The EbC50- and ErC50 - values were both > 3.3 mg/L.