Magnesium potassium titanium oxide

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 November 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study has been performed according to OECD and EC guidelines and according to GLP principles.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2000

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

(1984)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Version / remarks:

(1988)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

436-900-9

EC Name:

-

Cas Number:

39290-90-9

Molecular formula:

Hill Empirical formula: K(0.2-0.7) Mg(0.4) Ti(1.6) O(3.7-3.95) CAS Empirical formula: K(0.2-0.7) Mg(0.4) Ti(1.6) O(3.7-3.95)

IUPAC Name:

Magnesium Potassium Titanium Oxide

Details on test material:

Batch: 0G99
White powder
Expiry date: 21 August 2001
Test substance storage: At room temperature in the dark

Sampling and analysis

Analytical monitoring:

not required

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
Tested in duplicate. The synthetic sewage feed (16 mL) and an adequate amount of the test substance were mixed and made up to 300 mL with Milli-Q water. The test substance was added quantitatively to the test vessels at a concentration of 100 mg/L. Activated sludge (200 ml) was added and the mixture was aerated in a 500 mL beaker during the contact time (30 minutes) .

In each test series two controls without test substance were tested, one at the start and one at the end.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The sludge was coarsely sieved, washed and diluted with tap-water. A small amount of the sludge was weighed and dried at ca. 105°C to determine the amount of suspended solids (3.5 g/L of sludge, as used for the test). Before use the pH was checked (measured value: 7.5).
The batch of sludge was used on subsequent days (maximum four days), therefore 50 mL of synthetic sewage feed was added to each litre of activated sludge at the end of each working day. The sludge was kept aerated at test temperature until use.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

30 min

Remarks on exposure duration:

aeration and stirring during the exposure period

Post exposure observation period:

After the contact time, a well mixed sample of the 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. Oxygen consumption was measured and recorded for approximately 10 min. During measurement, the sample was not aerated but continuously stirred on a magnetic stirrer. The pH was determined in the remaining part of the reaction mixture.

Test conditions

Test temperature:

The temperature of the test medium was 20.0°C.

pH:

7.1-7.2

Dissolved oxygen:

at the start of the test: 7.1-7.3 mg O2/L

Nominal and measured concentrations:

nominal 100 mg/L. No measured concentration.

Details on test conditions:

TEST SYSTEM
- Test vessel: all glass, 300 and 1000 mL (oxygen) bottles
- Aeration: continuously during exposure with clean, oil-free air. A pipette was used as aeration device.
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

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

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Oxygen consumption for approximately 10 minutes after the exposure period to determine the respiration rate.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: loading rate

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: substance is highly insoluble in water; EC50 is above the water solubility level.

Details on results:

No significant inhibition in respiration rate of the sludge was recorded at 100 mg TERRACESS P per litre.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
The EC50 of 3,5-dichlorophenol was 7 mg/L which is within the acceptable range of 5-30 mg/L, with 88% inhibition at 32 mg/L, 68% at 10 mg/L and 24% at 3.2 mg/L
- Other:

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Under the test conditions, TERRACESS P was not toxic to waste water (activated sludge) bacteria at a nominal concentration of 100 mg/L.