Calcium nitrite

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:

No data

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Good-quality study, conducted to GLP. Certain water quality parameters (e.g. hardness, conductivity) were not reported.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 and 100 mg/L (replicates [R] R1-R3 and R4-R6 pooled) at 0 and 72 hours for quantitiative analysis.
- Sampling method: Duplicate samples were taken at 0 and 72 hours
- Sample storage conditions before analysis: Samples were stored at approximately -20 deg C for further analysis if necessary

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 100 mg of test material was dissolved in culture medium and the volume adjusted to 500 mL to give a 200 mg/L stock solution. This was subsequently mixed with algal suspension (500 mL) to give the required test concentration (100 mg/L).
- Eluate: no data
- Differential loading: no data
- Controls: test medium
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): not applicable
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)): not applicable
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): no data

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Green alga
- Strain: CCAP 276/20
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa, Dunstaffnage Marine Laboratory, Oban, Argyll, Scotland
- Age of inoculum (at test initiation): no data
- Method of cultivation: Cultures were maintained in the laboratory by the periodic replenishment of the culture medium

ACCLIMATION
- Acclimation period: yes (duration not specified)
- Culturing media and conditions (same as test or not): The culture was maintained in the laboratory at a temperature of 21+/-1 deg C under conditions of continuous illumination (7000 lux) and constant aeration
- Any deformed or abnormal cells observed: no data

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Remarks on exposure duration:

As recommended in applicable guideline

Post exposure observation period:

Not applicable

Hardness:

No data

Test temperature:

24+/-1 deg C

pH:

7.3 (0 hours) - 7.8 (72 hours)

Dissolved oxygen:

No data

Salinity:

No data

Conductivity:

No data

Nominal and measured concentrations:

Nominal: 0 and 100 mg/L
Measured: limit concentration was 98.7 mg/L (R1-3) or 99.6 mg/L (R4-6) at 0 hr and 93.3 mg/L (R1-3) or 94.8 mg/L (R4-6) at 72 hr

Details on test conditions:

TEST SYSTEM
- Test vessel: conical flasks fitted with foam bungs
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: glass, 250 mL, no data, 100 mL
- Aeration: no data
- Type of flow-through (e.g. peristaltic or proportional diluter): no data
- Renewal rate of test solution (frequency/flow rate): no data
- Initial cells density: 10,000 cells/mL
- Control end cells density: no data
- No. of organisms per vessel: no data
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): not applicable

GROWTH MEDIUM
- Standard medium used: yes (essentially AAP medium)
- Detailed composition if non-standard medium was used: included Na2SeO3.5H2O (0.000010 mg/L)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: no data
- Total organic carbon: no data
- Particulate matter: no data
- Metals: no data
- Pesticides: no data
- Chlorine: no data
- Alkalinity: no data
- Ca/mg ratio: no data
- Conductivity: no data
- Culture medium different from test medium: no
- Intervals of water quality measurement: no data

OTHER TEST CONDITIONS
- Sterile test conditions: no data
- Adjustment of pH: no data
- Photoperiod: Continuous illumination
- Light intensity and quality: 7000 lux
- Salinity (for marine algae): not applicable
- Other: Constant shaking at 150 rpm

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: no data
- Chlorophyll measurement: no data

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable
- Justification for using less concentrations than requested by guideline: limit concentration

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 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): no data
- Observation of abnormalities (for algal test): no data
- Unusual cell shape: no data
- Colour differences: no data
- Flocculation: nod data
- Adherence to test vessels: no data
- Aggregation of algal cells: no data
- Any stimulation of growth found in any treatment: growth at the limit concentration was 10% higher than that of the control at 72 hr
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no data
- Effect concentrations exceeding solubility of substance in test medium: no data

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Area under the growth curve at 72 hr was 5.09 x 10^6 for the control and 6.25 x 10^6 for the limit concentration, corresponding to a 23% increase. The growth rate was 0.049 for the control and 0.054 for the limit concentration, corresponding to a 10% increase in growth.

Analysis of the test concentrations at 0 and 72 hours showed measured test concentrations to be near nominal, hence the EC50 values were estimated beased on the nominal test concentrations only. Additional analysis of the test samples was conducted for the presence of sodium nitrate at both 0 and 72 hours in order to determine whether conversion of nitrite to nitrate occurred. The results obtained showed measured test concentrations of less than 1% of nominal for sodium nitrite at 0 hours and 5% of nominal at 72 hours thereby indicating that no conversion occurred.

Mean cell densities for the control were 9.01 x 10^3, 2.74 x 10^4, 5.71 x 10^4 and 3.00 x 10^5 at 0, 24, 48 and 72 hr, respectively. Analogous values for the limit concentration were 7.72 x 10^3, 2.72 x 10^4, 6.68 x 10^4 and 3.71 x 10^5 (at the various respective time points)

Validity criteria fulfilled:

not specified

Conclusions:

In a guideline study, to GLP, growth and biomass were unaffected in green algae exposed to freshwater containing sodium nitrite at a nominal limit concentration of 100 mg/L for 72 hours.

Executive summary:

In an OECD Test Guideline 201 study, conducted according to GLP, sodium nitrite was studied for its ability to inhibit the growth of freshwater Desmodesmus subspicatus (green algae) under static conditions.

The test substance was added to culture medium and the organisms (initial cell density 10,000 cells/mL) exposed at 0 or 100 mg/L (nominal) for 72 hours. There was no inhibitory effect on growth rate or biomass as a result of the treatment; growth at the limit concentration was actually 10% higher than that of the control at 72 hr.

Based on these results, and in the absence of any adverse effects, the 72-hr NOEC (both growth rate and biomass) for the test material was considered to be 100 mg/L. The 72-hr EC50 is evidently somewhat higher than this limit concentration.

Description of key information

No data on calcium nitrite were identified.

 

In a GLP study conducted according to OECD Test Guideline 201, growth and biomass were unaffected in green algae exposed to freshwater containing sodium nitrite at a nominal limit concentration of 100 mg/L for 72 hours (JAFA, 2005).

Additional information

No data on calcium nitrite were identified.

 

In an OECD Test Guideline 201 study, conducted according to GLP, sodium nitrite was studied for its ability to inhibit the growth of freshwater Desmodesmus subspicatus (green algae) under static conditions. The test substance was added to culture medium and the organisms (initial cell density 10,000 cells/mL) exposed at 0 or 100 mg/L (nominal) for 72 hours. There was no inhibitory effect on growth rate or biomass as a result of the treatment; growth at the limit concentration was actually 10% higher than that of the control at 72 hr. Based on these results, and in the absence of any adverse effects, the 72-hr NOEC (both growth rate and biomass) for the test material was considered to be 100 mg/L. The 72-hr EC50 is evidently somewhat higher than this limit concentration (JAFA, 2005).

Sodium nitrite is closely related to calcium nitrite, and is considered a suitable surrogate for read-across for this endpoint. [See read-across justification report in IUCLID section 13 for details.]