Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
other information
Study period:
Dec 1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: well reported guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report Date:
1992

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): hydrocortisone-21-acetate (ZK 5192)
- Analytical purity: 99.4%
- Lot/batch No.: 20048246
- Expiration date of the lot/batch: Sep 1995

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no

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

Results and discussion

Effect concentrationsopen allclose all
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
> 100 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:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate

Any other information on results incl. tables

No inhibiton of respiration due to hydrocortisone-21 -acetate was observed at any concentration tested.

The reference substance showed a EC50 of 7.9 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
the EC10/EC50 of hydrocortison-21 -acetate to activated sludge microorganisms is higher than 100 mg/L
Executive summary:

The toxicity to activated sludge miccroorganisms was studied in a respiration inhibition test according to OECD 209. The microorganisms were incubated for 30 min with the test compound at a nominal loading of 100 mg/L, which was above the solubility level. No inhibiton of respiration was observed. Therefore, the EC10/EC50 of hydrocortison-21 -acetate to activated sludge microorganisms is higher than 100 mg/L.