Toxicity to microorganisms.001

Toxicity to microorganisms.001

Administrative data

Purpose flag:

key study

Study result type:

read-across from supporting substance (structural analogue or surrogate)

Study period:

From 2002-01-16 to 2002-01-18

Reliability:

2 (reliable with restrictions)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report Date:

2002

Materials and methods

Test guideline

Qualifier:

according to

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test)

Deviations:

no

Principles of method if other than guideline:

not applicable

GLP compliance:

yes

Remarks:

but there is no certificate

Test materials

Identity of test material same as for substance defined in section 1 (if not read-across):

no

Test material identityopen allclose all

Test material identity 1

Identifier:

CAS number

Identity:

7758-19-2

Test material identity 2

Identifier:

EC number

Identity:

231-836-6

Test material identity 3

Identifier:

IUPAC name

Identity:

sodium chlorite

Details on test material:

- Name of test material (as cited in study report): sodium chlorite
- Molecular formula (if other than submission substance): no data
- Molecular weight (if other than submission substance): no data
- Smiles notation (if other than submission substance): no data
- InChl (if other than submission substance): no data
- Structural formula attached as image file (if other than submission substance): no data
- Substance type: no data
- Physical state: Colourless to light yellow liquid
- Analytical purity: 31.13 % (w/w) in purified water 
- Impurities (identity and concentrations): no data
- Composition of test material, percentage of components: no data
- Isomers composition: no data
- Purity test date:2001-11-06
- Lot/batch No.: 6624
- Expiration date of the lot/batch: no data
- Stability under test conditions: no data
- Storage condition of test material: at room temperature and protected from the light

Details on properties of test surrogate or analogue material:

PHYSICO-CHEMICAL PROPERTIES
- Melting point: no data
- Boiling point: no data
- Vapour pressure: 2.7 kg/cm3
- Water solubility (under test conditions): in all proportions at 20°C
- Henry's law constant: no data
- log Pow: no data
- pKa: no data
- Stability in water: no data
- Stability in light: no data
- pH dependance on stability:13

OTHER PROPERTIES (if relevant for this endpoint)
- Results of test for ready biodegradability: no data
- Other: none

Analytical monitoring:

no

Details on sampling:

- Concentrations: 0.1, 0.316, 1, 3.16, 10, 31.6, and 100 mg/L and inoculum at 1.6 g/L of sodium chloride

- Sampling method: Oxygen consumption was measured for approximately 10 minutes after an aeration for 3 hr. Each concentration was prepared separately by adding 16 mL of sewage feed to each of the flask which was made up to 300 mL with water only in the case of the controls or a nominal mixture of water and stock solution in the case of the test solutions. Each mixture was then made up to 500 mL by adding 200 mL of inoculum was 1.6 g/L (+- 10%). The solutions were prepared every 15 min for test times of 3 hours.

- Sample storage conditions before analysis: no data

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: test item was dissolved at 0.642 g/L, i.e. 200 mg/L of active component sodium chlorite, in dechlorinated water. The stock solution was then agitated during one hour.
- Eluate: dechlorinated water
- Differential loading: no data
- Controls: no data
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): not applicable
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): not applicable
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no data

Test organisms

Test organisms (species):

activated sludge

Details on inoculum:

- Laboratory culture: activated sludge collected from a water treatment works containing effluent from a predominantly domestic origin
- Method of cultivation: The inoculum was maintained under agitation for one day before the test. 
- Preparation of inoculum for exposure: As the sludge was not used immediately, 50 mL of sewage feed was prepared using dechlorinated water and analytical grade reagents following OECD recommendations.
- Pretreatment: no data
- Initial biomass concentration: no data

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

no data

Test conditions

Hardness:

no data

Test temperature:

20 - 23 °C

pH:

6.0 - 8.0

Dissolved oxygen:

no data

Salinity:

bot applicable

Nominal and measured concentrations:

Initial concentrations: 
0.1, 0.316, 1, 3.16, 10, 31.6 and 100 mg/L
(Doses are equivalent to 0.075, 0.24, 0.75, 2.4, 7.5, 24 and 75 mg chlorite/L)

Details on test conditions:

Controls:
2 controls contained inoculum only at 1.6 g/L

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol, 99.1%, is a white powder labelled 02611ES-030

Results and discussion

Effect concentrationsopen allclose all

Effect concentrations 1

Duration:

3 h

Endpoint:

EC50

Effect conc.:

> 100 other: mg sodium chlorite/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

respiration rate

Effect concentrations 2

Duration:

3 h

Endpoint:

EC50

Effect conc.:

> 75 other: mg chlorite/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

respiration rate

Details on results:

3 hr EC50 of sodium chlorite > 100 mg/L

Inhibition of the respiration rate at 0.1, 0.316, 1, 3.16, 10, 31.6 and 100 mg/L were 9 %, 11 %, 3 %, 14 %, 14 %, 22 % and 35 %, respectively, relative to the mean of the controls. Hence, a significant inhibition of the respiration rate (> 15% relative to mean of controls) was noted from 31.6 mg/L/

Results with reference substance (positive control):

3 h EC50 of Reference item > 13.2 mg/L with 95% confidence limits of 11.3 – 15.6 mg/L

Reported statistics and error estimates:

no data

Any other information on results incl. tables:

No other informations

Applicant's summary and conclusion

Conclusions:

The validity criteria were fulfilled. The 3 h EC50 of sodium chlorite was > 100 mg/L for activated sludge (equivalent to >75 mg chlorite/L).

Executive summary:

Sodium chlorite at 31.12% in purified water, on the respiration of activated sewage sludge was evaluated using a 3-hours static test according to OECD Guideline 209. 7 test solutions were tested: 0.1, 0.316, 1, 3.16, 10, 31.6, and 100 mg/L. The results obtained demonstrated that EC50(3h) > 100 mg/L of sodium chlorite for activated sludge. All validity criteria were fulfilled.

Validity criteria fulfilled:

yes