Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
21 March 2003
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study has been performed according to OECD and/or EC guidelines and according to GLP principles. However, the test was carried out with a filtrate of a supersaturated test solution at a nominal concentration exceeding the water solubility limit.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report Date:
2003

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
(1984)
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): KY-MA
- Substance type: white to light pink powder
- Physical state: solid
- Stability in water: at least 96 hours
- Storage condition of test material: RT in the dark

Sampling and analysis

Analytical monitoring:
not required

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Pretreatment: Sludge was sieved, washed and diluted wtih tap water.
- Initial biomass concentration: 3.0 g/L

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
30 min

Test conditions

Test temperature:
19.0-22.0 degrees C
pH:
6.8-7.0
Nominal and measured concentrations:
100 mg/L nominal concentration; no concentrations were measured, but the solubility in water of KY-MA is very low (0.006 mg/L), so it can be assumed that the concentrations were at maximum solubility for KY-MA.
Details on test conditions:
TEST SYSTEM
- Test vessel: 1L glass test, 300 mL oxygen bottels
- Material, size, headspace, fill volume: test: 1L glass bottle with 500 mL fill volume
- Aeration: continuous during contact time (no aeration but stirring during oxygen measurement)
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per reference control (replicates): 3


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Milli-Q reverse osmosis purified tap water

OTHER TEST CONDITIONS
- Adjustment of pH: No

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Oxygen consumption

TEST CONCENTRATIONS
- Test concentration: 100 mg/L (nominal)
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol

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:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
All test solution concentrations were presumably above solubility, as the nominal concentrations of test substance were 100 mg/L and the solubility of KY-MA in water is 0.006 mg/L. This test concentration (limit test level) showed no toxicity towards sludge microorganisms: 1 and -1% inhibition. A negative value indicates stimulation of the respiration rate of the sludge. The value of -1% is considered at not significant. The nominal EC50 value is > 100 mg/L. The NOEC is 100 mg/L.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Relevant effect levels: 30% inhibition at 3.2 mg/L, 63% inhibition at 10 mg/L, 89% at 32 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The nominal EC50 value is > 100 mg/L and the NOEC is 100 mg/L.
Executive summary:

An activated sludge respiration inhibition study was performed according to OECD 209. The limit test was performed at nominal 100 mg/L, which is significantly above the solubility of KY-MA (0.006 mg/L). This test concentration showed no toxicity towards sludge microorganisms. Therefore the nominal EC50 value is > 100 mg/L and the NOEC is 100 mg/L.