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Toxicity to microorganisms

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Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
Data is from Peer reviewed journal

Data source

Reference
Reference Type:
publication
Title:
THE ASSESSMENT OF THE POSSIBLE INHIBITORY EFFECT OF DYESTUFFS ON AEROBIC WASTE-WATER BACTERIA EXPERIENCE WITH A SCREENING TEST
Author:
Dr. D. Brown, Dr. H.R. Hitz, Dr. L. Schafer
Year:
1981
Bibliographic source:
Chemosphere, Vol. I0, No. 3, PP 245 - 261, 1981

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: as mentioned below
Principles of method if other than guideline:
Activated sludge respiration inhibition test: The test principle involves measuring the respiration rate of an activated sludge and comparing it with the respiration rate of the same activated sludge under identical conditions, but in the presence of the chemical under test.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid
Details on test material:
- Name of the test material: 3',6'-bis(diethylamino)spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one
- Molecular formula: C28H30N2O3
- Molecular weight: 442.556 g/mol
- Substance type: Organic
- Smiles: C12(c3c(Oc4c1ccc(c4)N(CC)CC)cc(N(CC)CC)cc3)c1c(cccc1)C(O2)=O
- Physical State: Solid
Specific details on test material used for the study:
- Name of the test material: 3',6'-bis(diethylamino)spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one
- Molecular formula: C28H30N2O3
- Molecular weight: 442.556 g/mol
- Substance type: Organic
- Smiles: C12(c3c(Oc4c1ccc(c4)N(CC)CC)cc(N(CC)CC)cc3)c1c(cccc1)C(O2)=O

Sampling and analysis

Analytical monitoring:
not specified
Details on sampling:
No data

Test solutions

Vehicle:
yes
Details on test solutions:
No data

Test organisms

Test organisms (species):
activated sludge
Details on inoculum:
Where possible activated sludge should be obtained from a sewage works treating predominantly domestic sewage. If this is not convenient, the activated sludge may be obtained from a sewage works treating predominantly industrial waste water. On the return to the laboratory, the sludge is centrifuged and washed with tap water. This procedure is repeated three times. A small amount of the centrifuged wet sludge is weighed and dried. After drying the ratio R of the weight of the dry solid to that of the wet centrifuged sludge is known. From this ratio R the amount of wet sludge can be calculated which has to be suspended in tap water in order to obtain an activated sludge with a mixed liquor suspended solids level of 4 g dry solids/litre. 50 ml OECD concentrate (2.2) is added to each litre of the activated sludge prepared as described above; this is then aerated overnight in a room at 20°C + 2°C, and kept aerated for use during the day. If the same sludge has to be used on subsequent days (up to a maximum of 4) a further 50 ml/litre of OECD concentrate sewage is added at the end of each working day.

Study design

Test type:
static
Water media type:
freshwater
Total exposure duration:
3 h

Test conditions

Hardness:
No data
Test temperature:
20 ± 2°C
pH:
7-8
Dissolved oxygen:
<2.5 mg/l
Salinity:
No data
Conductivity:
No data
Nominal and measured concentrations:
100 mg/l
Details on test conditions:
- Test vessel: ACTIVATED SLUDGE RESPIRATION RATE APPARATUS
- Type (delete if not applicable): open / closed: No data
- Material, size, headspace, fill volume: 500 ml flask
- Aeration: Yes
- Type of flow-through: "Pasteur" pipette
-Renewal rate of test solution (frequency/flow rate): No data
- No. of organisms per vessel: No data
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates):No data
- Biomass loading rate: No data
Reference substance (positive control):
not specified

Results and discussion

Effect concentrations
Key result
Duration:
3 h
Dose descriptor:
IC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Details on results:
For those chemicals whose respiration rate is at least 80% of the control, the IC50 (concentration for 50% inhibition of respiration rate) is recorded as 100 mg/l.
Results with reference substance (positive control):
No data
Reported statistics and error estimates:
No data

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The IC50 value (concentration for 50% inhibition of respiration rate) for the test chemical 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one on activated sludge (aerobic bacteria) is determined to be >100 mg/1 after 3 hrs of exposure.
Executive summary:

A screening method based on the measurement of the respiration rate of activated sludge for assessing the possible inhibitory effect of dyestuffs on aerobic waste-water bacteria. The test principle involves measuring the respiration rate of an activated sludge and comparing it with the respiration rate of the same activated sludge under identical conditions, but in the presence of the chemical under test. The test was carried out in activated sludge respiration rate apparatus with constant 20 ± 2°C and pH about 7-8. The test concentration used was 100 mg/l. OECD recommended synthetic sewage was used as feed, while activated sludge was obtained from a sewage works treating predominantly domestic sewage or from a sewage works treating predominantly industrial waste water. The respiration rate of an activated sludge and the respiration rate of activated sludge with test chemical were noted down. In order to calculate the inhibitory effect of a particular chemical at 100 mg/l test concentration its respiration rate is expressed as a percentage of the mean of the two control respiration rates. For those chemicals whose respiration rate is at least 80% of the control, the IC50 (concentration for 50% inhibition of respiration rate) is recorded as >100 mg/l.

Thus, IC50 value (concentration for 50% inhibition of respiration rate) for the test chemical 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one on activated sludge (aerobic bacteria) is determined to be >100 mg/1 after 3 hrs of exposure.