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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:
comparable to guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))
Deviations:
no
GLP compliance:
yes
Test organisms (species):
activated sludge of a predominantly domestic sewage
Test type:
not specified
Water media type:
other: Milli-RO water purified by reverse osmosis
Limit test:
yes
Total exposure duration:
3 h
Test temperature:
18-21 °C
pH:
The pH in all test vessels, before addition of sludge was between 7.5 and 7.6. After the 3 hour exposure period the pH was between 7.4 and 8.3.
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
Key result
Duration:
3 h
Dose descriptor:
other: NOELR
Effect conc.:
> 1 000 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
inhibition of total respiration
Duration:
3 h
Dose descriptor:
other: ELR50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
inhibition of total respiration
Validity criteria fulfilled:
yes
Conclusions:
No statistically significant inhibition of the respiration rate of the sludge was recorded at a loading rate of 1000 mg Disperse Blue 359 per litre.
The batch of activated sludge was tested for sensitivity with the reference item 3,5-dichlorophenol and showed normal sensitivity.
The study met the acceptability criteria prescribed by the study plan and was considered valid.
Disperse Blue 359 was not toxic to waste water (activated sludge) bacteria at a loading rate of 1000 mg/L (NOELR). The ELR50was above 1000 mg/L
Executive summary:

The test item was not sufficiently soluble to allow the preparation of a 10 g/L stock solution in water. Therefore, the test item – Milli-RO water mixtures were magnetically stirred for approximately 10 minutes. Subsequently. Synthetic medium, sludge and Milli-RO water were added resulting in the required loading rates. Optimal contact between the test item and test organisms was ensured by applying continuous aeration and stirring during the 3 hour exposure period. Thereafter, oxygen consumption was recorded for approximately 10 minutes.

In a combined limit/range-finding test loading rates of 10, 100 and 1000 mg/L were tested. The highest loading rate was tested in triplicate, lower loading rates consisted of one replicate. Furthermore, at 1000 mg/L an abiotic control (1 replicate) was tested. Responses were compared to the controls.

No statistically significant inhibition of the respiration rate of the sludge was recorded at a loading rate of 1000 mg Disperse Blue 359 per litre.

The batch of activated sludge was tested for sensitivity with the reference item 3,5-dichlorophenol and showed normal sensitivity.

The study met the acceptability criteria prescribed by the study plan and was considered valid.

Disperse Blue 359 was not toxic to waste water (activated sludge) bacteria at a loading rate of 1000 mg/L (NOELR). The ELR50was above 1000 mg/L

Description of key information

The test item was not sufficiently soluble to allow the preparation of a 10 g/L stock solution in water. Therefore, the test item – Milli-RO water mixtures were magnetically stirred for approximately 10 minutes. Subsequently. Synthetic medium, sludge and Milli-RO water were added resulting in the required loading rates. Optimal contact between the test item and test organisms was ensured by applying continuous aeration and stirring during the 3 hour exposure period. Thereafter, oxygen consumption was recorded for approximately 10 minutes.

In a combined limit/range-finding test loading rates of 10, 100 and 1000 mg/L were tested. The highest loading rate was tested in triplicate, lower loading rates consisted of one replicate. Furthermore, at 1000 mg/L an abiotic control (1 replicate) was tested. Responses were compared to the controls.

No statistically significant inhibition of the respiration rate of the sludge was recorded at a loading rate of 1000 mg Disperse Blue 359 per litre.

The batch of activated sludge was tested for sensitivity with the reference item 3,5-dichlorophenol and showed normal sensitivity.

The study met the acceptability criteria prescribed by the study plan and was considered valid.

Disperse Blue 359 was not toxic to waste water (activated sludge) bacteria at a loading rate of 1000 mg/L (NOELR). The ELR50was above 1000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L
EC10 or NOEC for microorganisms:
1 000 mg/L

Additional information

The test item was not sufficiently soluble to allow the preparation of a 10 g/L stock solution in water. Therefore, the test item – Milli-RO water mixtures were magnetically stirred for approximately 10 minutes. Subsequently. Synthetic medium, sludge and Milli-RO water were added resulting in the required loading rates. Optimal contact between the test item and test organisms was ensured by applying continuous aeration and stirring during the 3 hour exposure period. Thereafter, oxygen consumption was recorded for approximately 10 minutes.

In a combined limit/range-finding test loading rates of 10, 100 and 1000 mg/L were tested. The highest loading rate was tested in triplicate, lower loading rates consisted of one replicate. Furthermore, at 1000 mg/L an abiotic control (1 replicate) was tested. Responses were compared to the controls.

No statistically significant inhibition of the respiration rate of the sludge was recorded at a loading rate of 1000 mg Disperse Blue 359 per litre.

The batch of activated sludge was tested for sensitivity with the reference item 3,5-dichlorophenol and showed normal sensitivity.

The study met the acceptability criteria prescribed by the study plan and was considered valid.

Disperse Blue 359 was not toxic to waste water (activated sludge) bacteria at a loading rate of 1000 mg/L (NOELR). The ELR50was above 1000 mg/L