Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From June 17th to 21st, 1996
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1996
Report Date:
1996

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
April 4th, 1984
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
30 min

Test conditions

Test temperature:
21 °C
pH:
pH negative control = 8.0 - 8.2
pH test substance = 8.0 - 8.2
pH positive control = 8.0
Nominal and measured concentrations:
Nominal concentrations: 3.2, 10, 32, 50, 100 mg/l
Details on test conditions:
Continuous aeration during the 30 minutes test period using compressed air at an air-flow rate of approximately 0.2 l per minute.
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol at 1, 3.2, 10, 32, 50 mg/l

Results and discussion

Effect concentrations
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Details on results:
The respiration rate of aerobic waste water bacteria was not inhibited (-7.1 % to -12.3 %) when exposed to the test article conoentrations in the range from 3.2 to 100 mg/l. Based on these results the EC50 (30 minutes) can be defined as >100 mg/l.
Results with reference substance (positive control):
The respiration rate of the activated sludge was not inhibited (-2.8 % and -1 .9 %) at the two lowest rconcentrations of 1.0 and 3.2 mg/l. At 10, 32 and 50 mg/l, the respiration rate was inhibited by 21.0, 67.6 and 73.7 %, respectively. The EC50 (30 minutes) determined by linear regression was calculated to be 20.5 mg/l. The results confirmed the suitability of the activated sludge and method used.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
EC50 (30 minutes) > 100 mg/l.