Calcium acetylide

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:

2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

inital cell density higher than recommended

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The test samples of the algae growth inhibition test were received in Sarstedt tubes.
The test samples were stored at -18 °C until sample analysis.

Vehicle:

no

Details on test solutions:

Preparation of the test solutions:
The test substance Calciumcarbide is soluble in water. Therefore, the test solution was prepared with test medium and by weighing and transferring of the test substance directly in the medium. The test solutions were prepared corresponding to the required test concentrations (determined in
a range finding test) in the following way:
- Filling the flasks with 995 ml test medium
- Addition of 5 ml alga stock culture inoculum into the test medium to a volume of 1000 ml
- Addition of the test substance weighed per vessel directly into the test medium

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: fresh-water green algae
- Strain: Scenedesmus subspicatus 86.81 SAG
- Source: purchased from “Pflanzenphysiologisches Institut” of the University of Göttingen, Germany, in 1998
- Age of inoculum (at test initiation):
- Method of cultivation: axenic stock cultures grew up in conical flasks containing 200 ml nutrient solution (alga medium); algae were shaken permanently and incubated at (23 ± 2) °C under continuous lighting (8000 lx); weekly an amount of a senior culture was transferred with a sterile pipette into flasks containing fresh medium

ACCLIMATION
- Acclimation period:
- Culturing media and conditions (same as test or not): yes
- Any deformed or abnormal cells observed:

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

Not applicable

Hardness:

Not reported

Test temperature:

22.0-22.1 °C

pH:

7.99 (at t= 0)

Salinity:

not applicable

Nominal and measured concentrations:

Nominal: 0 (control), 2.6, 5.6, 12.4, 27.3, 60.0 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 1000 ml Erlenmeyer flask with a metal cap
- Type (delete if not applicable): closed
- Test volume: 1000 ml
- Test medium: alga cultivation medium (see below)
- Aeration: no
- Initial cells density: 1.7 x 10^4 cells/ml
- No. of vessels per concentration (replicates): 3 + 1 at each concentration not loaded with algae for measurement and analytical purpose
- No. of vessels per control (replicates): 5


CULTURING CONDITIONS
Axenic stock cultures grew up in conical flasks containing 200 ml nutrient solution (alga medium); algae were shaken permanently and incubated at (23 ± 2) °C under continuous lighting (8000 lx); weekly an amount of a senior culture was transferred with a sterile pipette into flasks containing fresh medium

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
The following alga medium was used for culturing and in the test:
NH4Cl 15 mg/l
MgCl2 × 6 H2O 12 mg/l
CaCl2 × 2 H2O 18 mg/l
MgSO4 × 7 H2O 15 mg/l
KH2PO4 1.6 mg/l
FeCl3 × 6 H2O 0.08 mg/l
Na2EDTA × 2 H2O 0.1 mg/l
H3BO3 0.185 mg/l
MnCl2 × 4 H2O 0.415 mg/l
ZnCl2 3 × 10-3 mg/l
CoCl2 × 6 H2O 1.5 × 10-3 mg/l
CuCl2 × 2 H2O 1 × 10-5 mg/l
Na2MoO4 × 2 H2O 7 × 10-3 mg/l
NaHCO3 50 mg/l
The pH of this medium after equilibration with air was approximately 8. The medium was sterilised by autoclavation (121 °C, 1 bar) except for the NaHCO3 solution which was sterilised by membrane filtration (0.2 μm).

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuous
- Light intensity and quality: universal white type fluorescent lamp; spectral range 400-700 nm; approximately 8000 lx


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations by counting the cells in a counting chamber (“Neubauer-Zählkammer”) by means of a microscope.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

12 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

46 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.:

5.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

2.7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

12 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): No abnormal response was observed in any concentration.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Regarding the NOEC and LOEC`s, the results were proved by means of multiple comparison procedure for comparing several treatments. This procedure is a variance test (ANOVA / DUNNETT’S t-test), testing the significance of the differences between each of the treatments compared to the mean values of each group (5 treatments). The significance F is compared with F(k-1; n-k; a). The F value is less than F(k-1; n-k; a) if groups are equal. The analysis itself was
computed by a programme for personal computers by RATTE (EASY ASSAY: Algae Growth Inhibition).

Standard equations were used to calculate inhibition of cell growth (Ia) and inhibition of growth rate (Ia*). The analysis itself was computed by a programme for personal computers by RATTE (EASY ASSAY: Algae Growth Inhibition).

For details regarding cell concentrations, percentage inhibition of the cell growth and growth rate, results of the analytical determination of calcium carbide in the test solutions, sample analysis as well as pH-values and temperatures please refer to the pdf document attached to this endpoint.

Validity criteria fulfilled:

yes

Remarks:

The cell concentration in the control cultures increased by a factor of more than 16 within three days (i.e. by a factor of 33.1).

Conclusions:

The 72 hr NOErC and ErC50 of calcium carbide to the algae Scenedesmus subspicatus is 5.6 mg/L and 46.5 mg/L, respectively.

Executive summary:

In a 72 hour acute toxicity study, the cultures of Scenedesmus subspicatus were exposed to calcium carbide at nominal concentrations of 0 (control), 2.6, 5.6, 12.4, 27.3, 60.0 mg/L under static conditions in accordance with the OECD guideline 201 (1984). The NOEC, EC10 and EC50 values based on growth rate were 5.6, 12.9 and 46.5 mg/L, respectively. The % growth inhibition in the treated algal culture as compared to the control ranged from -1.7 to 148.6.

No abnormal response was observed in any concentration.

This toxicity study is classified as acceptable and satisfies the guideline requirements for aquatic algae toxicity study.

Results Synopsis

Test Organism: Scenedesmus subspicatus

Test Type: Static

72 hr ErC10: 12.9 mg/L

72 hr ErC50: 46.5 mg/L

72 hr NOErC: 5.6 mg/L

Endpoint(s) Effected: growth rate

Description of key information

The 72 hr NOErC and ErC50 of calcium carbide to the algae Scenedesmus subspicatus is 5.6 mg/L and 46.5 mg/L, respectively.

Key value for chemical safety assessment

EC50 for freshwater algae:

46.5 mg/L

EC10 or NOEC for freshwater algae:

5.6 mg/L

Additional information

In a 72 hour acute toxicity study, the cultures of Scenedesmus subspicatus were exposed to calcium carbide at nominal concentrations of 0 (control), 2.6, 5.6, 12.4, 27.3, 60.0 mg/L under static conditions in accordance with the OECD guideline 201 (1984). The NOEC, EC10 and EC50 values based on growth rate were 5.6, 12.9 and 46.5 mg/L, respectively. The % growth inhibition in the treated algal culture as compared to the control ranged from -1.7 to 148.6.

No abnormal response was observed in any concentration.

This toxicity study is classified as acceptable and satisfies the guideline requirements for an aquatic algae toxicity study.

Results Synopsis

Test Organism: Scenedesmus subspicatus

Test Type: Static

72 hr ErC10: 12.9 mg/L

72 hr ErC50: 46.5 mg/L

72 hr NOErC: 5.6 mg/L

Endpoint(s) Effected: growth rate