Tetraammineplatinum (II) diacetate

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EC Commission Directive 87/302/E - Part C

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Platinum(2+) tetraammine diacetate

Cas Number:

0127733-97-5

IUPAC Name:

Platinum(2+) tetraammine diacetate

Test material form:

solid

Remarks:

crystal powder

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: a stock solution of 0.5 g/L was prepared by adding 504.9 mg test item to 1000 mL of Milli-RO water (tap water purified by reverse osmosis; Millipore Corp.). Twenty-five minutes of magnetic stirring was used to accelerate dissolution and to ensure homogeneity. The pH of the clear and colourless stock solution was 6.4. A concentration of 100 mg test item/L, corresponding to 100 mL of the prepared stock solution in 500 mL final volume, was tested in duplicate.
- Controls: activated sludge without test item
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): none

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture: microorganisms in activated sludge
- Name and location of sewage treatment plant where inoculum was collected: Municipal sewage treatment plant: 'Waterschap de Maaskant', 's-Hertogenbosch, The Netherlands
- 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 approximately 105 °C to determine the amount of suspended solids (3.3 g/L of sludge, as used for the test). The batch of the sludge was used one day after collection, and therefore 50 mL of synthetic sewage feed was added per L of activated sludge at the end of the collection day. The sludge was kept aerated at test temperature until use.
- Initial biomass concentration: not reported
- Synthetic sewage feed: Mixture of 16 g peptone, 11 g meat extract, 3 g urea, 0.7 g NaCl, 0.4 g CaCl2.2H2O, 0.2 g MgSO4.7H2O, 2.8 g K2HPO4. This mixture dissolved in dilution water, made up to 1 L and filtered. The pH was 6.8 and adjusted with 1 M NaOH to 7.2.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

30 min

Test conditions

Test temperature:

19.6 - 20.9 °C

pH:

8.2 - 8.3

Nominal and measured concentrations:

Nominal concentration: 100 mg test item/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 300-mL glass oxygen bottles and 1-L glass test bottles
- Aeration: yes, during the contact time using a pipette as an aeration device
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 4
- Sludge concentration (weight of dry solids per volume): 3.3 g/L of suspended solids
- Biomass loading rate: not reported
- Performance of the test: the synthetic sewage feed (16 mL) and an adequate amount of the test substance solution were mixed and made up to 300 mL with dilution water. Activated sludge (200 mL) was added to provide a final volume of 500 mL. the mixture was then aerated in a 1-L bottle during the contact time. Then, a well mixed sample of contents was poured into a 300-mL oxygen bottle, and the flask was sealed with an oxygen electrode connected to a recorder, forcing the air out of the vessel. During measurement, the sample was not aerated but continuously stirred on a magnetic stirrer.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Milli-RO water - tap water purified by reverse osmosis and subsequently passed over activated carbon and ion-exchange cartridges

OTHER TEST CONDITIONS
- Photoperiod: not reported

EFFECT PARAMETERS MEASURED: oxygen consumption was measured and recorded for approximately 10 minutes after 30 minutes of contact time

TEST CONCENTRATIONS
- Range finding study: not performed

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

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 on result:

other: Pt concentrations calculated based on % Pt in the test material.

Effect concentrations 2

Key result

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 46.95 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Pt

Basis for effect:

inhibition of total respiration

Effect concentrations 3

Key result

Duration:

30 min

Dose descriptor:

EC10

Effect conc.:

> 46.95 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Pt

Basis for effect:

inhibition of total respiration

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: none reported
- The mean respiration rate of blank controls was 35 mg O2/L/hour.
- Coefficient of variation of respiration rate in control replicates: 0 %
- The respiration rate from each vessel (as mg O2/L/hour) was calculated from the linear part of the respiration curve. No EC50 of the test item could be calculated because the test substance was found to be non-toxic at the concentration tested of 100 mg test item/L.

Results with reference substance (positive control):

The percentage inhibition was plotted against the logarithm of the concentrations and the EC50 was determined using linear regression analysis. The EC50 of 3.5-dichlorophenol was determined to be 14 mg/L.

Any other information on results incl. tables

Table 1. pH, oxygen concentration, oxygen consumption and percentage inhibition after 30 minutes contact time of platinum(2 +) tetraammine diacetate to microbes in activated sludge

	Concentration mg test item/L	Oxygen concentration at the start (mg O2/L)	Oxygen consumption (mg O2/L/hour)	% Inhibition	pH
Control - Replicate 1	0	7.8	34	-	8.3
Control - Replicate 2	0	7.5	33	-	8.2
Mean Control's replicates	-	-	34	-	-
Test item - Replicate 1	100	7.0	37	-10*	8.3
Test item - Replicate 2	100	6.5	37	-10*	8.2

*Negative values indicate stimulation of respiration rate of the sludge. These values were considered as not significant.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Based on nominal concentrations, the 30-min EC50 of platinum(2+) tetraammine diacetate on activated sludge was determined to be >100 mg test item/L corresponding to >46.95 mg Pt/L. The 30-min EC10 value was >46.95 mg Pt/L.

Executive summary:

An activated sludge respiration inhibition test was conducted with platinum(2+) tetrammine diacetate. The study is reliable without restrictions, being GLP-compliant, and having followed standard test guidelines (OECD 209, ISO 8192, EC Commission directive 87/302/E, Part C).

A nominal concentration of 100 mg test item/L was tested in duplicate, along with a blank control and a positive control. The test item was aerated for a 30-minute period in the presence of activated sewage sludge with the addition of synthetic sewage as a respiratory substrate. The rate of respiration was determined after 30 minutes of contact time. All validity criteria were met and no protocol deviations were recorded. Based on nominal concentrations, the 30-min EC50 of platinum(2+) tetraammine diacetate on activated sludge was determined to be >100 mg test item/L corresponding to >46.95 mg Pt/L. The 30-min EC10 value was >46.95 mg Pt/L.