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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
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes
Details on sampling:
After 3 hours, the respiration rate was measured every minute.
Details on test solutions:
5mg, 10mg, 20mg, 40mg and 80mg test substance was added to 200mL test medium respectively. The suspensions were treated with ultrasonic wave for 15min to make the suspension homogeneous.
Test organisms (species):
activated sludge, domestic
Details on inoculum:
The activated sludge was obtained from Liede Sewage Treatment Plant of Guangzhou. The sludge was removed any coarse particles and impurities by filtration, then was washed with tap water (repeated for 3 times), after centrifuging the supernatant liquid phase was decanted and the solid material resuspended in deionized water. A small amount of the washed sludge was weighed, thereafter dried and the ratio of wet to dry weight was calculated as 14.4g/L. The final concentration of activated sludge during the test suspension was 1.6g dry material per litre. The sludge was not used on the day of collection, so 50mL synthetic sewage was added to each litre of the activated sludge prepared as described above; the sludge was then aerated at 20°C±2°C until use. Before used the pH was checked
Test type:
static
Water media type:
freshwater
Total exposure duration:
3 h
Test temperature:
20.5°C-22.0°C
Nominal and measured concentrations:
10, 20, 40, 80 and 160 mg/L test substance concentration.
Reference substance (positive control):
yes
Remarks:
3,5-dochlorophenol
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 160 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:
NOEC
Effect conc.:
160 mg/L
Nominal / measured:
nominal
Results with reference substance (positive control):
The 3h- EC50 of 3, 5-dichlorophenol was 7.2mg/L within the accepted range of 5 mg/L to 30 mg/L

The results showed that the respiration rates of control at the beginning and end of test were 27.4mg/(L·h) and 26.1mg/(L·h), respectively; the difference between the two sets of control was 2.5%, within 15% of each other. The test solutions with test substance concentrations of 10mg/L, 20mg/L, 40mg/L, 80mg/L, 160mg/L were exposed to activated sludge and respiration rates were 27.7mg/(L·h), 28.4mg/(L·h), 27.2mg/(L·h), 27.6mg/(L·h) and 29.7mg/(L·h). The respiration inhibition rates were -3.4%, -6.3%, -1.5%, -3.2% and -11.0%, respectively. Under 5 concentrations, the test substance had no significant inhibitory effect (<15%) on the respiration rate of activated sludge after the incubation period of three hours and was stimulative of the expiration rates. The results revealed that the 3h-EC50 of the test substance was clearly higher than the nominal concentration of 160 mg/L under the present test conditions and the NOEC may be stabolished at 160 mg/L.

Validity criteria fulfilled:
yes
Conclusions:
An OECD 209 Activated Sludge Repiration Inhibition Test on sodium 2-(dodecanoyloxy)propane-1-sulfonate (SLMI) was performed. The 3h-EC50 of the test substance was higher than 160 mg/L and the NOEC may be established at 160 mg/L.
Executive summary:

An OECD 209 Activated Sludge Repiration Inhibition Test on sodium 2 -(dodecanoyloxy)propane-1 -sulfonate (SLMI) was performed. The 3h-EC50 of the test substance was higher than 160 mg/L and the NOEC may be established at 160 mg/L.

Endpoint:
activated sludge respiration inhibition testing
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Letter report of well conducted GLP summary
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
GLP compliance:
yes
Details on test solutions:
The test substance was weighed directly into the test chambers at concentrations ranging from 62.5 to 1000 mg/L.
Test organisms (species):
activated sludge of a predominantly domestic sewage
Test type:
not specified
Total exposure duration:
3
Test temperature:
20
pH:
7.2
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
Duration:
3 d
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
Validity criteria fulfilled:
yes
Conclusions:
In a study performed to OECD 209, the test substance (SCI) did not inhibit microorganism activity at the highest concentration tested (1000 mg/L)

Description of key information

In a study performed to OECD 209 an EC50 of 1000 mg/L established for read-across substance SCI.


In an additional study performed to OECD 209, SLMI acheived a EC50 greater than 160 mg/L. The NOEC may be established at 160 mg/L.

Key value for chemical safety assessment

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

Additional information

Two studies have been performed to establish the toxicity effect on micro-organisms.

In a study performed to OECD 209 on the read-across substance SCI established a EC50 (3h) of >1000 mg/L.

Another study performed to OECD 209 on SLMI established a NOEC of 160 mg/L (highest concentration tested).