Calcium nitrite

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13-15 April 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Produced by BASF on 23 November 2009. 47219706D0 vom 23.11.2009
- Expiration date of the lot/batch: November 2012
- Purity test date: not specified

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material:
- Stability under test conditions: "The stability of the test substance under storage conditions over the test period was guaranteed by the sponsor and the sponsor holds this responsibility".
- Solubility and stability of the test substance in the solvent/vehicle: water solubility 848 g/L
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: not specified

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: not specified
- Preliminary purification step (if any): not specified
- Final dilution of a dissolved solid, stock liquid or gel: not specified
- Final preparation of a solid: not specified

FORM AS APPLIED IN THE TEST (if different from that of starting material): not specified

Analytical monitoring:

no

Details on sampling:

Not applicable

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 2.0 g of the test substance was added to about 800 mL of demineralized water and stirred at room temperature until the test substance was completely dissolved. After that the pH-value was measured (measured value = 7.3). The stock solution was made up to 1L with demineralized water.
- Eluate: not applicable
- Differential loading: not applicable
- Controls: To prepare the blank control assays 150 mL of demineralized water and 8 mL synthetic medium were given to the blank control test vessels.
- 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.): "The stock solution appeared clear and no undissolved test substance was visible".

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture: activated sludge from a municipal wastewater treatment plant
- Name and location of sewage treatment plant where inoculum was collected: Mannheim, Germany
- Method of cultivation: no data
- Preparation of inoculum for exposure: The activated sludge suspension was sieved with a fine woven mesh (mesh size about 1 mm). This suspension was pre-aerated overnight at room temperature.
- Pretreatment: The next day the sludge suspension was washed once with tap water and the suspension was adjusted to 7.5 g/L dry matter.
- Initial biomass concentration: "An aliquot of this suspension was added to the test vessels to obtain a sludge concentration of 1.5 g/L dry substance."

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Remarks on exposure duration:

As recommended in applicable guideline

Post exposure observation period:

Not applicable

Hardness:

No data

Test temperature:

20.5 - 20.8 °C

pH:

7.1-7.2 [7.9-8.0 after incubation].

Dissolved oxygen:

Oxygen concentration during aeration: > 2.5 mg/L
Oxygen concentration immediately before measurement: > 6.5 mg/L

Salinity:

Not applicable

Conductivity:

No data

Nominal and measured concentrations:

62.5, 125, 250, 500 or 1000 mg/L (nominal). 62.4, 125, 250, 500 or 1000 mg/L (actual).

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer-flasks
- Type (delete if not applicable): no data
- Material, size, headspace, fill volume: nominal volume 250 mL
- Aeration: "with pressure air" [not further specified]
- No. of vessels per concentration (replicates): 1
- No. of vessels per blank control (replicates): 2
- No. of vessels per vehicle control (replicates): not applicable
- No. of vessels per abiotic control (replicates): not applicable
- Sludge concentration (weight of dry solids per volume): 1.5 g/L
- Weight of dry solids per volume of reaction mixture per unit of time: no data
- Nutrients provided for bacteria: no data
- Nitrification inhibitor used: not applicable
- Biomass loading rate: no data

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: [synthetic medium] 8 mL/test vessel of 100-fold concentrated OECD medium
- Particulate matter: no data

OTHER TEST CONDITIONS
- Adjustment of pH: not considered neccesary
- Photoperiod: not specified
- Light intensity: not specified
- Details on termination of incubation: "After 180 minutes incubation the mixtures in the test vessels were placed subsequently into a closed oxygen measuring cell".

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : oxygen respiration rates (oxygen consumption) measured for 8-10 minutes after incubation

TEST CONCENTRATIONS
- Spacing factor for test concentrations: "According to the test guidelines, at least 5 concentrations in a geometric series with a separation factor of ≤ 3.2 were used".
- Justification for using fewer concentrations than requested by guideline: not applicable
- Range finding study : not specified

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

510 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

- 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: not applicable
- Adsorption (e.g. of test material to the walls of the test container): no data
- Blank controls oxygen uptake rate: 1.5 mg/L in 6 minutes (15 mg/L/hr)
- Coefficient of variation of oxygen uptake rate in control replicates: not applicable (both blank controls had same uptake rate)

Results with reference substance (positive control):

- Results with reference substance valid? Yes (within the range of 5-30 mg/L after 180 minutes)
- Relevant effect levels: EC50 7.2 mg/L

Reported statistics and error estimates:

The oxygen consumption rates were determined after 180 minutes of exposure and used to calculate the inhibition effects at particular test concentrations compared to the mean of the 2 blank controls. These values were used for the determination of the ECx by the probit method based on Finney with the software TOXRAT. The values were given with an accuracy of 2 significant digits.

The results with the reference substance indicate that the microorganisms are responding normally to toxicant stress.

Respective (rounded) EC10, EC20, EC50 and EC80 values of 210, 280, 510 and 940 mg/L were calculated for the test material.

Validity criteria fulfilled:

yes

Remarks:

The deviation of the two blank controls is <15 % O2 consumption from the higher value and the EC50 of 3,5-dichlorophenol is in the range of 5-30 mg/L.

Conclusions:

In a guideline study, to GLP, sodium nitrite was studied for its ability to inhibit the respiration (oxygen consumption) of freshwater activated domestic sewage under static conditions. The 3-hr EC50 for sodium nitrite was determined to be 510 mg/L.

Executive summary:

In an OECD Test Guideline 209 study, conducted according to GLP, the ability of sodium nitrite to inhibit the respiration (oxygen consumption) of freshwater activated domestic sewage was investigated under static conditions.

The test substance was added to culture medium at (nominal) concentrations of 0 (blank control), 62.5, 125, 250, 500 or 1000 mg/L and incubated for 3 hours. The reference substance (positive control; 2,5-dichlorophenol) was treated in a similar way. Following this, the respiration rate (oxygen consumption) of each treated and control inoculum was measured for 6 minutes. The oxygen consumption rates were used to calculate the inhibition effects at each test concentration (relative to the controls) and the degree of inhibition was subsequently evaluated by Probit analysis.

The blank controls and reference substance behaved as expected, confirming the validity of the study. The 3-hr EC50 for sodium nitrite was determined to be 510 mg/L.

Description of key information

No data on calcium nitrite were identified.

 

In a GLP study conducted according to OECD Test Guideline 209, sodium nitrite was studied for its ability to inhibit the respiration (oxygen consumption) of freshwater activated domestic sewage under static conditions. The 3-hr EC50 for sodium nitrite was determined to be 510 mg/L (Hammer, 2010).

Additional information

No data on calcium nitrite were identified.

 

In an OECD Test Guideline 209 study, conducted according to GLP, the ability of sodium nitrite to inhibit the respiration (oxygen consumption) of freshwater activated domestic sewage was investigated under static conditions. The test substance was added to culture medium at (nominal) concentrations of 0 (blank control), 62.5, 125, 250, 500 or 1000 mg/L and incubated for 3 hours. The reference substance (positive control; 2,5-dichlorophenol) was treated in a similar way. Following this, the respiration rate (oxygen consumption) of each treated and control inoculum was measured for 6 minutes. The oxygen consumption rates were used to calculate the inhibition effects at each test concentration (relative to the controls) and the degree of inhibition was subsequently evaluated by Probit analysis. The blank controls and reference substance behaved as expected, confirming the validity of the study. The 3-hr EC50 for sodium nitrite was determined to be 510 mg/L (Hammer, 2010).

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.]