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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
7 April 2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Not a full guideline study, although based on OECD TG209, and carried out to GLP. Considered scientifically acceptable.
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
yes
Remarks:
A contact time of 30 mins only was used, whereas the current guideline requires a 3 hr contact time. Only one concentration (100 mg/L) tested, in duplicate. For a preliminary test, current guidelines recommend three concentrations are tested in triplicate
Qualifier:
according to
Guideline:
ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)
Deviations:
not specified
GLP compliance:
yes
Analytical monitoring:
no
Details on sampling:
Not applicable
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution of 0.5 g/L was prepared by adding 504.9 mg of test material (white crystalline powder) to 1 L of Milli-RO water. 25 minutes of magnetic stirring was used to accelerate the dissolution and to ensure homogeneity. A concentration of 100 mg/L, corresponding to 100 mL stock solution in a 500 mL final volume, was used for the test.
- Eluate: Not applicable
- Differential loading: Not applicable
- Controls: Test medium without test substance
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Not applicable
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): Not applicable
- Evidence of undissolved material (e.g. precipitate, surface film, etc): Test material was completely soluble in test medium.
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Laboratory culture: Sludge was obtained from a municipal sewage treatment plant: Waterschap de Maaskant, 's-Hertogenbosch, the Netherlands, receiving predominantly domestic sewage.
- Method of cultivation: No data
- Preparation of inoculum for exposure: The sludge was coarsely sieved, washed and diluted with tap-water. A small amount of the sludge was weighted and dried at 105 deg C to determine the amount of suspended solids. The pH was 7.6 on the day of sampling and 7.9 on the day of testing.
- Pretreatment: No data
- Initial biomass concentration: 3.3 g/L as suspended solids
Test type:
not specified
Water media type:
freshwater
Limit test:
no
Total exposure duration:
30 min
Remarks on exposure duration:
See 'Any other information on materials and methods incl. tables' below
Post exposure observation period:
None
Hardness:
No data
Test temperature:
19.6 - 20.9 deg C
pH:
7.2 initially, rising to 8.3 at the end of the test.
Dissolved oxygen:
6.5-7.8 mg O2/L at the start of the test
Salinity:
Not applicable
Nominal and measured concentrations:
100 mg/L nominal (measured concentration was not analysed).
Details on test conditions:
TEST SYSTEM
- Test vessel: All-glass, approximately 300 mL oxygen bottles and 1 L test bottles
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: All-glass, approximately 300 mL oxygen bottles and 1 L test bottles
- Aeration: Aerated using a pipette during the contact time but not during measurement.
- Type of flow-through (e.g. peristaltic or proportional diluter): No data
- 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): Not applicable
- Biomass loading rate: No data

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Milli Q water

OTHER TEST CONDITIONS
- Adjustment of pH: pH was adjusted from 6.8 to 7.2 using 1M NaOH
- Photoperiod: No data
- Light intensity: No data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Inhibition of respiration

TEST CONCENTRATIONS
- Spacing factor for test concentrations: Not applicable
- Justification for using less concentrations than requested by guideline: Not applicable
- Range finding study: No
- Test concentrations: Not applicable
- Results used to determine the conditions for the definitive study: Not applicable
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol
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
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
Details on results:
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No data
- Effect concentrations exceeding solubility of substance in test medium: Not applicable
Results with reference substance (positive control):
- Results with reference substance valid? Yes, the EC50 for 3,5-dichlorophenol was within the accepted range (5-30 mg/L)
- Relevant effect levels: EC50 of 14 mg/L
Reported statistics and error estimates:
No data

Table 1: Reference substance and control data on pH, oxygen concentration, oxygen consumption and respiratory inhibition.

 Flask  Concentration (mg/L)  Initial oxygen concentration (mg O2/L)  Oxygen consumption (mg O2/L/hr)  % Inhibition  pH
 Control 1  0  7.0  35  -  8.1
 Control 2  0  7.4  35  -  8.2
 Mean control      35    
 Reference 1  3.2  7.1  30  14  8.1
 Reference 2  10  7.7  21  40  8.1
 Reference 3  32  8.1  10  71  8.2

Table 2: Test substance and control data on pH, oxygen concentration, oxygen consumption and respiratory inhibition.

 Flask  Concentration (mg/L)  Initial oxygen concentration (mg O2/L)  Oxygen consumption (mg O2/L/hr)  % Inhibition  pH
 Control 3  0  7.8  34  -  8.3
 Control 4  0  7.5  33  -  8.2
 Mean control      34    
 Test 1  100  7.0  37  -10  8.3
 Test 2  100  6.5  37  -10  8.2
Validity criteria fulfilled:
yes
Conclusions:
In a study based on OECD TG209, to GLP, the 30-min EC50 of platinum (2+) tetraammine diacetate to activated sludge respiration is greater than 100 mg/L (>46.95 mg Pt/L; considered the study NOEC).
Executive summary:

The inhibitory effect of platinum (2 +) tetraammine diacetate on the respiration rate of aerobic wastewater micro-organisms of activated sludge was investigated in a 30 minute respiration inhibition test based on OECD guidelines (TG 209) and carried out to GLP.

A single nominal limit concentration of 100 mg/L was tested. In addition, four controls and three different concentrations of the reference substance 3, 5 -dichlorophenol in the range from 3.2 to 32 mg/L were tested in parallel. The 30 -min EC50 of the reference substance 3,5 -dichlorophenol was calculated to be 14 mg/L and was within the accepted range of 5–30 mg/L; thus, confirming suitability of the activated sludge. 

At the nominal limit concentration of 100 mg/L, platinum (2 +) tetraammine diacetate had no inhibitory effect on the respiration rate of activated sludge after an incubation period of 30 minutes (considered the study NOEC). Therefore, the 30 -min EC50 could not be quantified but is evidently higher than 100 mg/L (nominal), equivalent to >46.95 mg Pt/L, under these study conditions.

Description of key information

In a study based on OECD TG209, to GLP, the 30-min EC50 of tetraammineplatinum(II) diacetate to activated sludge respiration is greater than 100 mg/L (>46.95 mg Pt/L; considered the study NOEC) (Desmares-Koopmans, 2006).

Key value for chemical safety assessment

Additional information

The inhibitory effect of tetraammineplatinum(II) diacetate on the respiration rate of aerobic wastewater micro-organisms of activated sludge was investigated in a 30 minute respiration inhibition test based on OECD guidelines (TG 209) and carried out to GLP (rated Klimisch 2).

A single nominal limit concentration of 100 mg/L was tested. In addition, four controls and three different concentrations of the reference substance 3,5 -dichlorophenol (ranging from 3.2 to 32 mg/L) were tested in parallel. The 30 -min EC50 of the reference substance 3,5 -dichlorophenol was calculated to be 14 mg/L and was within the accepted range of 5–30 mg/L; this confirmed the suitability of the activated sludge for this test.

At the nominal limit concentration of 100 mg/L, tetraammineplatinum(II) diacetate had no inhibitory effect on the respiration rate of activated sludge after an incubation period of 30 minutes (considered the study NOEC). Therefore, the 30 -min EC50 could not be quantified but is evidently >100 mg/L (nominal), equivalent to >46.95 mg Pt/L, under the conditions of this study (Desmares-Koopmans, 2006).