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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
10.06.1997 - 13.08.1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
Adopted: 4 April 1984
GLP compliance:
yes
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
- Water solubility (under test conditions): 500 mg/L


Analytical monitoring:
no
Details on sampling:
- Concentrations: 6.3, 12.5, 25.0, 50.0, 100 mg/L
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Source: municipal sewage plant Sindlingen (Frankfurt/ Main)
- Suspension: 450 ml/L, after centrifugation 30.03 g/ sedimented sludge (dry mass: 3.56g/L)
- Preparation of inoculum for exposure: activated sludge was 3x centrifuged, resuspended in water containing 0.9% NaCl
- Pretreatment: not adapted
- Initial biomass concentration: 1.6 g/L (dry mass, final concentration in test volume)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Remarks on exposure duration:
Incubation time with TS
Hardness:
no data
Test temperature:
19.3°C - 20.4°C
pH:
7.0 - 7.8 (after incubation)
Dissolved oxygen:
6.0 mg/L - 8.3 mg/L at test start
Salinity:
no data
Nominal and measured concentrations:
6.3, 12.5, 25.0, 50.0, 100 mg/L (nominal)
Details on test conditions:
TEST SYSTEM
- Material, size, headspace, fill volume: 200 mL
- Aeration: 50 L/h during incubation
- No. of vessels per concentration (replicates): two
- No. of vessels per control (replicates): three

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
Reference substance (positive control):
yes
Remarks:
3,5-dichlorphenol (5, 20, and 30 mg/L)
Duration:
3 h
Dose descriptor:
EC0
Effect conc.:
> 6.3 - < 12.5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: see report table 2 (page 8)
Duration:
3 h
Dose descriptor:
other: EC20
Effect conc.:
16 mg/L
Nominal / measured:
nominal
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.:
33 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
other: EC80
Effect conc.:
66 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50: 12 mg/L (C.I.: 8 mg/L - 15 mg/L, P=95 %)
Reported statistics and error estimates:
Calculation of EC20, EC50, and EC80: Probit-Analysis (Finney 1971), Confidence interval was uncalculable
Validity criteria fulfilled:
yes
Conclusions:
In an activated sludge, respiration inhibition test the EC50 (3 hours) was calculated to be between > 10 mg/L and 100 mg/L.
Executive summary:

The effect of n/i-C13/C15 amine on the respiration rate of activated sludge was assessed in a GLP study according to OECD 209.

Samples of activated sludge were exposed to the test substance at nominal concentrations of 6.3, 12.5, 25.0, 50.0 and 100.0 mg/L for 3 hours. Their rates of oxygen consumption were determined and compared with those of controles, which were established at the beginning and end of the culture series.

The reference inhibitor 3,5 -dichlorophenol (3,5 -DCP) was employed in the test at 5, 20 and 30 mg/L, as a positive control. The three-hour 50% effect concentration (EC50) for 3,5 -DCP was calculated to be 12 mg/L (95% confidence limits 8 - 15 mg/L). These results show that the rest was valid and that the sample of activated sludge employed was sentitve to inhibition.

n/i-C13/C15 amine had an inhibitory effect on the respiration rate of activated sludge, resulting in an EC 50 value of > 10 mg/L - 100 mg/L.

Description of key information

In an activated sludge, respiration inhibition test the EC50 (3 hours) was calculated to be between > 10 mg/L and 100 mg/L.

Key value for chemical safety assessment

Additional information

The effect of n/i-C13/C15 amine on the respiration rate of activated sludge was assessed in a GLP study according to OECD 209.

Samples of activated sludge were exposed to the test substance at nominal concentrations of 6.3, 12.5, 25.0, 50.0 and 100.0 mg/L for 3 hours. Their rates of oxygen consumption were determined and compared with those of controles, which were established at the beginning and end of the culture series.

The reference inhibitor 3,5 -dichlorophenol (3,5 -DCP) was employed in the test at 5, 20 and 30 mg/L, as a positive control. The three-hour 50% effect concentration (EC50) for 3,5 -DCP was calculated to be 12 mg/L (95% confidence limits 8 - 15 mg/L). These results show that the rest was valid and that the sample of activated sludge employed was sentitve to inhibition.

n/i-C13/C15 amine had an inhibitory effect on the respiration rate of activated sludge, resulting in an EC 50 value of > 10 mg/L - 100 mg/L.