Reaction mass of disodium hexatitanium tridecaoxide and disodium trititanium heptaoxide

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:

2010-06-29 to 2010-07-08

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP Guideline study reliable without restrictions

Justification for type of information:

Disodium titanate substance (EC 234-802-9) has the molecular formula Na2TiO3 and its composition is expressed as (Na2O)x(TiO2), where x is ranging from 0.1 to 6 according to the SIP. This substance, Reaction mass of Disodium Hexatitanate and Sodium Metatitanate, has a value of x = 0.21, calculated from XRF results, has been identified as a mixture of two specific types of disodium titanate and is therefore within the scope of the disodium titanate SIP. It is assessed therefore that disodium titanate is an acceptable read-across substance for Reaction mass of Disodium Hexatitanate and Sodium Metatitanate

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed, 2009-03-04

Analytical monitoring:

yes

Details on sampling:

Sampling for chemical analysis of test item concentrations at start and at end of exposure.

- Preparation of Samples for Chemical Analysis:
Samples from control and all test item concentrations were taken and analysed to determine the actual test item concentrations in comparison to the nominally applied concentrations. The control and test solutions were sampled in duplicate. The duplicate sample was kept separately as a reserve. After sampling and before transfer to the test site, the samples were stored at room temperature in the dark in polyethylene bottles.

- Sample Preparation / Analysis:
Unfiltered water samples from the aquatic toxicity study were sent to the analytical test site. All samples received were stored refrigerated at test site up to sample preparation. The water samples were filtered (0.45 µm), the filtrate acidified 1v/v (65% HNO3) and directly used for ICP-OES analysis to determine the content of dissolved titanium.

Vehicle:

no

Details on test solutions:

PREPARATION OF STOCK SOLUTION
A stock solution (water accommodated fraction, WAF) at a loading rate of nominal 100 mg test item/L was prepared by dissolving 180.3 mg of the test item in 1800 mL of reconstituted water. This stock solution was agitated for seven days by using a horizontal laboratory shaker at ambient temperature in the dark. The shaker was set to a frequency of 100 rpm to keep the test item in permanent suspension according to OECD (2001). After that, the stock solution was filtered (pore size 0.4 µm) using a glass fibre filter. The filtrate was used to prepare the desired test item concentrations by dilution with reconstituted water.

PREPARATION AND APPLICATION OF TEST SOLUTION
Corresponding volumes of the filtrate were taken and diluted with reconstituted water to prepare the test solutions. The following table describes the procedure for preparing the test solutions, and the control for the test.

Preparation of test solutions.
[1] [2] [3]
Control 0 1000
6.25 62.5 1000
12.5 125 1000
25 250 1000
50 500 1000
100 1800 1800

[1] Nominal test item concentration in % WAF at a loading rate of 100 mg test item/L
[2] Amount of stock solution in mL added to the measuring flask to prepare the test solutions
[3] Final volume of the test solutions in mL

The volume of the filtrate was large enough to prepare all test concentration levels and all analytical samples. The test solutions were filled into the test vessels and were placed into a temperature-controlled room for temperature adaptation.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Strain: Strauss, clone 5
- Source: ECT Oekotoxikologie GmbH since October 11, 2000. The organisms were originally supplied by Aventis, Frankfurt a. M., Germany
- Age at study initiation: less than 24 h
- Test Medium: Medium M4
- Holding conditions (same as test or not): yes, the same
- Type and amount of food: TetraMin®, Algae (Desmodesmus subspicatus), instant baker’s yeast suspension
- Feeding frequency: 3 times per week

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

no

Hardness:

Water Hardness: 244.7 (as mg/L CaCO3)
Total hardness in mg/L CaCO3 was calculated by multiplication of the hardness-value in °dH by 17.86

Test temperature:

Temperature: 19.8-21.3°C

pH:

7.7 - 7.8

Dissolved oxygen:

87-99 % (7.7-9.0 mg/L)

Salinity:

Conductivity: 625 µS/cm

Nominal and measured concentrations:

nominal conc.: 0 (control), dilution steps of 6.25, 12.5, 25, 50, 100% of the water-accommodated fraction (WAF) at a loading rate of 100 mg test item/L
measured conc.: the measured concentrations of titanium were below the limit of detection (LOD: 0.0027 mg/L regarding titanium determination) in all samples

Details on test conditions:

TEST SYSTEM
- Test vessel: glass beakers (300 mL; height: 5.5 cm; diameter: 9 cm) covered by glass lids
- Volume of test solution per test vessel: 150-180 mL
- Aeration: none
- Renewal rate of test solution: none
- No. of organisms per test vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Test medium: due to the chelating nature of components in the culture medium (Elendt Medium M4), reconstituted water according to OECD guideline No. 203 (OECD 1992) was used as test medium. The final concentration of the salts in the reconstituted water was: CaCl2 * 2 H2O: 294.0 mg/L, MgSO4 * 7 H2O: 123.0 mg/L, NaHCO3: 64.8 mg/L, KCl: 5.75 mg/L
- Conductivity: 625 µS/cm
- pH: 7.7
-Temperature: 21.9°C
- Diss. Oxygen: 99%
- Hardness: 244.7 as mg/L CaCO3
- Culture medium different from test medium: yes
- Intervals of water quality measurement: at start (0h) and at end of exposure (48h).

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Photoperiod: 16 h light / 8 h dark
- Light intensity: 395 to 616 lx

EFFECT PARAMETERS MEASURED: immobillity

TEST CONCENTRATIONS
- Range finding study: a preliminary range finding tests were performed at 0.001 to 100% of the water-accommodated fraction (WAF) at a loading rate of 100 mg test item/L. The highest treatment level showed effects up to 50% immobility after 48 h. Therefore, a definitive test was performed using the following concentration levels as dilution steps: 0, 6.25, 12.5, 25, 50, 100% of the water-accommodated fraction (WAF) at a loading rate of 100 mg test item/L.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (K2Cr2O7)

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 other: % of WAF

Nominal / measured:

nominal

Conc. based on:

other: WAF at a loading rate of 100 mg/L

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

other: EC20

Effect conc.:

68.88 other: % of WAF

Nominal / measured:

nominal

Conc. based on:

other: Dilution of WAF at a loading rate of 100 mg/L

Basis for effect:

mobility

Remarks on result:

other: lower 95%-cl: 30.35 % WAF, upper 95%-cl: 15813.39 % WAF

Key result

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

23.51 other: % of WAF

Nominal / measured:

nominal

Conc. based on:

other: Dilution of WAF at a loading rate of 100 mg/L

Basis for effect:

mobility

Remarks on result:

other: lower 95%-cl: 0.48 % WAF, upper 95%-cl: 58.90 % WAF

Details on results:

- Immobility of control after 48 h: 10%

Results with reference substance (positive control):

- Results with reference substance valid: yes
- Frequenz of testing: Potassium dichromate (K2Cr2O7) is tested as the reference item at least twice a year in order to determine the sensitivity of the organisms from the culture, and to demonstrate that the test conditions are appropriate.
- EC50/LC50: The reference test with potassium dichromate performed in May 2010 resulted in an EC50 (24 h) of 0.66 mg/L.
- Other: According to the OECD guideline EC50 (24h)-values for potassium dichromate obtained from different laboratories should range between 0.6 mg/L and 2.1 mg/L (OECD, April, 2004). The toxicity of the reference item is within this range. Therefore the results of this reference test are acceptable, the test conditions are reliable and the sensitivity of the organisms could be demonstrated.

Reported statistics and error estimates:

The immobility data were analysed using probit analysis with linear maximum likelihood regression. Abbott's correction for control mortality, and adjustment for normal-distribution were applied. The statistical software package ToxRat 2.10 Professional (ToxRat Solutions GmbH, Naheweg 15, D-52477 Alsdorf) was used for these calculations.

Validity criteria fulfilled:

yes

Conclusions:

A clear concentration-response relationship was not observed. Inhibition was not more than 30% at the higher test concentrations. It could therefore be demonstrated that the EC50 (48h) for Disodium titanate is higher than the water-accommodated fraction (WAF) at 100 mg/L.

Description of key information

A clear concentration-response relationship was not observed. Inhibition was not more than 30% at the higher test concentrations. It could therefore be demonstrated that the EC50 (48h) for Disodium titanate is higher than the water-accommodated fraction (WAF) at 100 mg/L.

Additional information

A clear concentration-response relationship was not observed. Inhibition was not more than 30% at the higher test concentrations. It could therefore be demonstrated that the EC50 (48h) for Disodium titanate is higher than the water-accommodated fraction (WAF) at 100 mg/L (nominal concentration).