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Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
20 July 1999
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
guideline version from 1993
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
1993
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
Batch no. 34-2127
Date of production: December 1998
Colour: colourless/yellowish
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Preparation of inoculum for exposure: The inoculum was washed, brought to a concentration of 5 g/l dry substance and aerated for about 24 hours. 50 ml were added to a total volume of 250 ml to obtain a concentration of 1 g/l dry substance in the test.
- Inoculum: concentration of dry substance: 1 g/l
- Pretreatment: none
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
30 min
Test temperature:
20±2 °C
pH:
7.4 (start) - 7.7 (end)
Dissolved oxygen:
7.9 (start) - 6.5 (after 6 min) mg/L O2/L
Nominal and measured concentrations:
Nominal test concentration: 1000 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer-vessel (nominal volume 250 ml)
- Type (delete if not applicable): closed
- Aeration: none
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 3
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
Duration:
30 min
Dose descriptor:
other: EC20
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
30 min
Dose descriptor:
other: EC80
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Key result
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
No respiration inhibition observed.


Results with reference substance (positive control):
EC50 ca. 23 mg/L (3,5-dichiorophenol)

MEASURED DATA blank control (BC) and test substance (TS) after 30 minutes incubation time

Vessel no.: BC1 BC2 BC3 my
BC
TS1
Concentration of test substance (mg/1) - - - - 1000
Added volume of stock solution(mVvessel) - - - - -
Direct addition (mg/vessel) - - - - 250.0
Oxygen concentration start (mg 02/I) 8.3 8.3 8.4 - 7.9
Oxygen concentration after 6 min (mg 02/l) 7.0 7.0 7.2 - 6.5
Oxygen consumption rate (mg02/I*6 min) 1.3 1.3 1.2 1.3 1.4
Oxygen consumption rate (mg02/1*h) 13 13 12 13 14
Specific oxygen consumption rate (mg02/g*h) 13 13 12 13 14
Change in oxygen consumption ratecompared with the blank control (%) - - - - -8

my BC = mean value of blank control

pH-VALUES  blank control (BC) and test substance (TS) after 30 minutes incubation time

Vessel no.: BC1 BC2 BC3   TS1
pH-value before adding the inoculum
before correction:
6.7 6.7 6.7   6.7
after correction: 7.5 7.2 7.4   7.4
pH-value after an incubation time of 30 min - - -   7.7
Validity criteria fulfilled:
yes
Remarks:
according to OECD 209 adopted 1993
Conclusions:
The test substance did not inhibit respiration of activated sludge microorganisms at 1000 mg/L. The derived 30min - EC50 (sludge microorganisms, respiration inhibition) > 1000 mg/L (nominal).
Executive summary:

The study investigated respiration inhibition of activated sludge microorganisms according to OECD guideline 209 (adopted 1993). Domestic activated sludge was used as inoculum. No inhibition of respiration was observed under static test conditions. The effect concentrations EC20 and EC50 (respiration inhibition) were derived at > 1000 mg/L after 30 minutes of exposure. In conclusion, the test substance was considered to not inhibit respiration of activated sludge microorganisms. The validity criteria of the test guideline (adopted 1993) were fulfilled. Despite of some deficiencies with respect to the updated guideline, the study was considered adequate and reliable for environmental hazard assessment.

Endpoint:
activated sludge respiration inhibition testing
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Please find endpoint specific justification in the read-across assessment report.
Reason / purpose:
read-across source
Reason / purpose:
assessment report
Key result
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks on result:
other: Effect conc. are identical for the submission substance, because target and source substance have the same MW.
Validity criteria fulfilled:
yes
Remarks:
according to OECD 209, adopted 1993
Conclusions:
The test substance did not inhibit respiration of activated sludge microorganisms at 1000 mg/L. The derived 30min - EC50 (sludge microorganisms, respiration inhibition) > 1000 mg/L (nominal).
Executive summary:

The study used as source investigated repiration inhibition of actived sludge microorganisms. The study results of the source compound were considered applicable to the target compound. Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13.

Description of key information

EC50 (sludge microorganisms, respiration) > 1000 mg/L (experimental, OECD 209)

Key value for chemical safety assessment

Additional information

No toxicity data concerning respiration inhibition of activated sludge is available for the submission substance. However, adequate and reliable data are reported here for a structural analogue (source substance 2,3 -butanediol). Please also refer to the read-across justification document.

In the reliable key study respiration inhibition of activated sludge microorganisms was investigated according to OECD guideline 209 (adopted 1993). Domestic activated sludge was used as inoculum. No inhibition of respiration was observed under static test conditions. The effect concentrations EC20 and EC50 (respiration inhibition) were derived at > 1000 mg/L after 30 minutes of exposure. In conclusion, the test substance was considered to not inhibit respiration of activated sludge microorganisms. The validity criteria of the test guideline (adopted 1993) were fulfilled. Despite of some deficiencies with respect to the updated guideline, the study was considered adequate and reliable for environmental hazard assessment.