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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2 June 1992 to 5 June 1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
No blank was included and results of reference substance are not stated.
Qualifier:
according to guideline
Guideline:
ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
not specified
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
Source: Laboratory Waste Water purification plant (according to OECD confirmatory test for surfactants). Concentration of inoculum was 6 g/L dry matter.
Test type:
other: respiration measurement (O2-decrease) within the testing period
Water media type:
freshwater
Limit test:
no
Total exposure duration:
30 min
Nominal and measured concentrations:
100, 180, 320, 560, 1000 mg/l
Details on test conditions:
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Activated sludge was mixed with an artificial, standardized wastewater. The diluted test material is added.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : The decrease of respiration is measured.
Reference substance (positive control):
yes
Remarks:
3,5 Dichlorophenol (CAS 25167-81-1)
Key result
Duration:
30 min
Dose descriptor:
EC10
Effect conc.:
53 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: read from concentration/effect curve
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
245 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
Test concentration [mg/L] versus (vs) Inhibition [%]
100 vs 26.2
180 vs 35.1
320 vs 57.4
560 vs 77.1
1000 vs 88.7
Results with reference substance (positive control):
Test data have been confirmed by the reference substance (raw data).
Reported statistics and error estimates:
The EC 50 value was determined graphically from the relation between concentration and inhibition effect (semilogarithmic scale)

Despite GLP, the purity of the test substance not stated, results of reference substance not stated, no blank included

Validity criteria fulfilled:
not applicable
Remarks:
The result is considered valid but some limitation are noted: no blank included, results of reference substance not stated, exposure time is not stated
Conclusions:
An EC50 and EC 10 value of 245 and 53 mg/L, respectively, was determined in a study conducted according to an appropriate test protocol, and in compliance with GLP.
Executive summary:

An activated sludge respiration inhibition test with Cyclacet has been performed, according to ISO 8192, which is similar to OECD TG 209. The sludge concentration was 6 g/l. The nominal test concentrations were 100, 180, 320, 560 and 1000 mg/l. A dose related increase in inhibition was seen from 26 to 88 mg/l. The EC50 and EC10 were found to be 245 and 53 mg/l respectively.

Description of key information

An activated sludge respiration inhibition test with Cyclacet has been performed, according to ISO 8192, which is similar to OECD TG 209. The sludge concentration was 6 g/l. The nominal test concentrations were 100, 180, 320, 560 and 1000 mg/l. A dose related increase in inhibition was seen from 26 to 88 mg/l. The EC50 and EC10 were found to be 245 and 53 mg/l respectively.

Key value for chemical safety assessment

EC50 for microorganisms:
245 mg/L
EC10 or NOEC for microorganisms:
53 mg/L

Additional information