Potassium titanium oxide (K1.88-2.13Ti8O16.94-17.07)

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

22/05/2003

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study has been performed according to OECD and EC guidelines and according to GLP principles. The restriction is due to the use of the read across approach: the test was performed not with Terracess TF but with Terracess L, a substance which is very similar in structure and physical/chemical properties.

Qualifier:

according to guideline

Guideline:

other: EEC Directive 67/548 amended November 18, 1987 (87/302), Part C: Methods for the determination of ecotoxicity, Publication No. L133, "Biodegradation: Activated sludge respiration inhibition test", adopted May 30, 1988.

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

not required

Vehicle:

no

Details on test solutions:

The synthetic sewage feed (16 ml) and an adequate amount of the test substance (49.6 mg) were mixed and made up to 300 ml with Milli-RO water. Activated sludge (200 ml) was added and the mixture was aerated in a 1 l bottle during the contact time, using a pipette as an aeration device. The flasks were filled up to 500 ml final volume. The final concentration was 100 mg/L. The test substance was tested in duplicate. Additionally, a control without test substance was included in duplicate. The reference substance was tested in triplicate.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The sludge was coarsely sieved and washed with tap-water. After concentration a small amount of the sludge was weighed and dried at ca. 105°C to determine the amount of suspended solids (3.1 g/l of sludge, as used for the test). Before use the pH was checked (measured value: 7.6).
The batch of sludge was used on the subsequent day, therefore 50 ml of synthetic sewage feed was added to each litre of activated sludge at the end of the day. The sludge was kept aerated at test temperature until use.

Test type:

other: aerobic

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

0.5 h

Post exposure observation period:

The contents were 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 minutes. 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 temperature:

20.2-20.5°C

pH:

8.0-8.1

Dissolved oxygen:

7.8-7.9 mg/L at the start of the test

Nominal and measured concentrations:

nominal 100 mg/L. No measured concentrations

Details on test conditions:

TEST SYSTEM
- Test vessel: All glass, 300 ml oxygen bottles and 1 l test bottles
- Aeration: continuous; clean, oil free air.
- 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 (Milli-RO) and subsequently passed over activated carbon and ion-exchange cartridges (Milli-Q) (Millipore Corp., Bedford, Mass., USA).


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

Reference substance (positive control):

yes

Remarks:

3.5 dichlorophenol

Key result

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

Key result

Duration:

30 min

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: loading rate

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: The EC50 of 3,5-dichlorophenol was in the accepted range of 5-30 mg/l (17.6 mg/l, regression line: Y = 58.04 X –22.24, Y = % inhibition and X = log concentration (mg/l)).

Validity criteria fulfilled:

yes

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

23 November 2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study has been performed according to OECD and EC guidelines and according to GLP principles. The restriction is due to the use of the read across approach: the test was performed not with Terracess TF but with Terracess P, a substance which is very similar in structure and physical/chemical properties.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

(1984)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(1988)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

not required

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 (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.

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 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

Key result

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:

Validity criteria fulfilled:

yes

Reference 3

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Justification for type of information:

1. HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
Please see attached justification.
2. CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL
Please see attached justification.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

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 on result:

other: Results are based on read across substance Terracess L

Key result

Duration:

30 min

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Loading rate

Basis for effect:

inhibition of total respiration

Remarks on result:

other: Results are based on read across substance Terracess L

Key result

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 on result:

other: Results are based on read across substance Terracess P

Remarks:

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

Description of key information

The EC50 for microorganisms exceeds the maximum solubility of the substance in water in studies on two similar substances. Therefore the weight of evidence shows that Terracess TF will not be toxic to microorganisms.  

Additional information

Under the conditions of test, Terracess L is not toxic to waste water (activated sludge) bacteria at a nominal concentration of 100 mg/L. The EC50 exceeded a loading rate of 100 mg/L.

Under the conditions of test, Terracess P is not toxic to waste water (activated sludge) bacteria at a nominal concentration of 100 mg/L. The EC50 exceeded a loading rate of 100 mg/L.