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Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
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:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Test organisms (species):
activated sludge
Total exposure duration:
3 h
Test temperature:
20 - 23 °C
pH:
6.0 - 8.0
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
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 100 other: mg sodium chlorite/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 75 other: mg chlorite/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
3 hr EC50 of sodium chlorite > 100 mg/LInhibition 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
Validity criteria fulfilled:
yes
Conclusions:
The 3 h EC50 of sodium chlorite was > 100 mg/L for activated sludge (equivalent to >75 mg chlorite/L).
Executive summary:

The aim of the test was to study the toxitity to activated sludge due to the test material.

The test procedure was OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test).

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).

The result was as follows:

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

Description of key information

Key study. The test procedure was OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test). The result was as follows: The 3 h EC50 of sodium chlorite was > 100 mg/L for activated sludge (equivalent to >75 mg chlorite/L).

Key value for chemical safety assessment

EC50 for microorganisms:
100 mg/L

Additional information

Key study. The test procedure was OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test). The result was as follows: The 3 h EC50 of sodium chlorite was > 100 mg/L for activated sludge (equivalent to >75 mg chlorite/L).