potassium titanium oxide (K2Ti6O13)

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

(Range-finding study) 29 January to 31 January 1999, (Definitive study) 24 March to 26 May 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

92/69/EEC (Annex V of Council Directive 67/548/EEC)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

(Date of inspection: 23 March 1998 Date of Signature: 21 July 1998)

Analytical monitoring:

yes

Details on sampling:

Water samples were taken from the control and the saturated solution (prepared from an initial test material dispersion at a concentration of 100 mg/I) (replicates R1 - R2 and R3 - R4 pooled) at 0 and 48 hours for quantitative analysis.
Duplicate samples were taken at each occasion and stored frozen (approximately -20°C) for further analysis, if necessary.

Vehicle:

no

Details on test solutions:

Due to the low aqueous solubility and high purity of the test material the test concentration used in the definitive study was a saturated solution prepared from an initial dispersion at a concentration of 100 mg/l.
Prior to addition of the test material, the reconstituted water was stirred by magnetic stirrer using a stirring rate such that a vortex depth of approximately 25% of the overall height of the water column was achieved. An amount of test material (1.0 g) was added to the vortex of 10 litres of reconstituted water to give an initial test material dispersion at a concentration of 100 mg/l. This was stirred for 47 hours. The stirring was stopped after 47 hours and the dispersion allowed to stand for 1 hour. The dispersion was then filtered through 0.2 pm filters to give a saturated solution.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea.

- Source: maintained in a laboratory culture originating from a strain supplied by the Institut National de Recherche Chimique Appliquee (IRCHA), France.

- Age at study initiation (mean and range, SD): 1st instar (Gravid adults were isolated 24 hours prior to the initiation of the test, the young daphnids produced overnight were then removed for testing).

- Method of breeding: parthenogenesis.

- Feeding during test: Each culture was fed daily.

- Food type: A suspension of mixed algae (predominantly Chlorella spp.).

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Post exposure observation period:

Not applicable.

Hardness:

Ca 250 mg CaCO3/L

Test temperature:

21ºC

pH:

7.8 - 7.9.

Dissolved oxygen:

8.3 - 8.6 mg O2/l.

Salinity:

No data.

Nominal and measured concentrations:

100 mg/l.

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed

- Material, size, headspace, fill volume: 250 ml glass jars

- Aeration: No.

- Renewal rate of test solution (frequency/flow rate): Not renewed.

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 4

- No. of vessels per control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
i) Stock Solutions
a) CaCI2·2H2O 11.76 g/I
b) MgSO4.7H2O 4.93 g/I
c) NaHCO3 2.59 g/I
d) KCl 0.23 g/I

ii) Preparation
An aliquot (25 ml) of each of solutions a-d was added to each litre (final volume) of deionised water with a conductivity of < 5 μS cm-1 and pH equal to 7.8 ± 0.2, adjusted (if necessary) with NaOH or HCI. The reconstituted water was aerated until the dissolved oxygen concentration was approximately air-saturation value.

OTHER TEST CONDITIONS
- Adjustment of pH: No.
- Photoperiod: 16 hours light and 8 hours darkness with 20 minute dawn and dusk transition periods.

EFFECT PARAMETERS MEASURED :
Any immobilisation or adverse reactions to exposure were recorded at 24 and 48 hours after the start of exposure. The criterion of effect used was that Daphnia were considered to be immobilised if they were unable to swim for approximately 15 seconds after gentle agitation.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 10 and 100 mg/l

- Results used to determine the conditions for the definitive study: No immobilisation was observed in the saturated solutions prepared from initial test material dispersions at concentrations of 10 and 100 mg/l. Based on this information 100 mg/l was selected for the (limit test).

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 0.27 mg/L

Nominal / measured:

estimated

Conc. based on:

dissolved

Basis for effect:

mobility

Remarks on result:

other: -

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 0.27 mg/L

Nominal / measured:

estimated

Conc. based on:

dissolved

Basis for effect:

mobility

Remarks on result:

other: -

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

> 0.27 mg/L

Nominal / measured:

estimated

Conc. based on:

dissolved

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.27 mg/L

Nominal / measured:

estimated

Conc. based on:

dissolved

Basis for effect:

mobility

Details on results:

No effects were observed.

Results with reference substance (positive control):

Not applicable.

Reported statistics and error estimates:

Not reported.

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of the test material to the freshwater invertebrate Daphnia magna has been investigated and based on an estimate of the dissolved concentration of the test material (limit of quantitation) gave a 48-Hour EC50 value of greater than 0.27 mg/1. Correspondingly the No Observed Effect Concentration was 0.27 mg/l.

Executive summary:

Methods

A study was performed to assess the acute toxicity of the test material to Daphnia magna.

The method followed that described in the OECD Guidelines for Testing of Chemicals (1984) No 202,"Daphnia sp, Acute Immobilisation Test and Reproduction Test" referenced as Method C.2 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC).

 

Procedures

Following a preliminary range-finding study, forty daphnids (4 replicates of 10 animals) were exposed to a saturated solution (prepared from an initial test material dispersion at a concentration of 100 mg/I) for 48 hours under static test conditions. Immobilisation and any adverse reactions to exposure were recorded after 24 and 48 hours.

 

Results

Analysis of the saturated solution (prepared from an initial test material dispersion at a concentration of 100 mg/I) at 0 and 48 hours showed the measured test concentrations to be below the limit of quantitation of the analytical method employed. This does not infer that no test material was in solution but that the dissolved concentration of test material (ie bioavailable to the test organisms) was below the limit of quantitation which was

assessed down to 0.27 mg/l. It was considered unnecessary and unrealistic to test saturated solutions prepared from initial test material dispersions at concentrations in excess of 100 mg/l. Therefore the 48-Hour EC50 based on the limit of quantitation was greater than 0.27 mg/I and correspondingly the No Observed Effect Concentration was 0.27 mg/l.

Description of key information

A study was performed to assess the acute toxicity of the test material to Daphnia magna.

Under the test condition, the dissolved concentration of test material (ie bioavailable to the test organisms) was below the limit of quantitation which was assessed down to 0.27 mg/L. It was considered unnecessary and unrealistic to test saturated solutions prepared from initial test material dispersions at concentrations in excess of 100 mg/L. Therefore the 48-Hour EC50 based on the limit of quantitation was greater than 0.27 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

> 0.27 mg/L

Additional information

Only one study is available for this endpoint and this will be submitted as a key study for the substance.

The 48-Hour EC50 based on the limit of quantitation was greater than 0.27 mg/L.

A study was performed to assess the acute toxicity of the test material to Daphnia magna. The method followed that described in the OECD TG 202 and conducted at a GLP-facility with a reliability of the study 1, according to the scoring system of Klimisch et al., 1997.