Dilithium titanate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental start date 13 January 2020. Experimental completion date 31 January 2020.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted in accordance with Commission Regulation (EC) No 761/2009 amending Regulation No 440/2008, Method C.3 ‘Freshwater Alga and Cyanobacteria, Growth inhibition test’ (2009) which is equivalent to OECD Guideline for Testing of Chemicals No. 201 (2006).

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

GLP compliance:

yes

Specific details on test material used for the study:

Test item : Lithium titanate
Chemical name : Lithium titanium oxide
CAS name : Lithium titanium oxide
CAS number : 12031-82-2
EC/NLP number : --
Sample provided by : LANXESS Deutschland GmbH
Empirical formula : Li2TiO3
Molecular mass : 109.8 g/mol
Date of receipt : 2016-09-27
Expiry date : 2021-09-23
Purity : > 98 %
Water solubility : 0.000383 g/L

Analytical monitoring:

yes

Details on sampling:

In order to avoid an impairment of the test system, an additional replicate was used for analysis and pH measurement at the beginning of the test. Chemical analysis and pH measurement at the end of the test were performed using replicate 1 of the test concentrations and the control vessels.
All samples were diluted 1:1 with acetonitrile and were stored at -18 °C in a deep freezer in 50 mL Sarstedt tubes until analysis.

Examined at test start (0h) and test end (72h).

Vehicle:

no

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Desmodesmus subspicatus (formerly Scene-desmus subspicatus)
- Strain: No. 86.81 SAG
- Source (laboratory, culture collection): 'The Collection of Algal Cultures' of the Institute of Plant Physiology at the University of Göttingen (Germany).
- Method of cultivation: Exponentially growing stock cultures were maintained in the test facility under constant temperature conditions (21 - 24 °C with a maximum fluctuation of +/- 2 °C) at a light intensity in the range 60 to 120 µE x m-2 x s-1 (measured in the range 400 to 700 nm using a spherical quantum flux meter). The growth medium (according to BRINGMANN & KÜHN (1977) was renewed once a week. Cell density measurements were made using a particle counter, Z2, Beckmann Coulter.

ACCLIMATION
Pre cultures were set up three days before the start of a test. They were grown under identical exposure conditions as the stock cultures, except from the use of a different growth medium.
Growth medium (OECD medium of OECD TG 201) was used for the growth of the algae in the pre cultures and the preparation of stock and test solutions of the test item.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

Water hardness of the final nutrient medium was 1.3 °dH, corresponding to 22.5 mg/L CaCO3.

Test temperature:

21-24°C

pH:

8.5 for test item concentration of 50 mg/L and 8.9 for test item concentration of 100 mg/L

Nominal and measured concentrations:

See Table 1.

Details on test conditions:

TEST SYSTEM
- Test vessel: 300 mL Erlenmeyer flasks with cotton stoppers
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 100 mL
- Aeration: none
- Initial cells density: approx. 5000 cells / mL
- No. of organisms per vessel: approx. 5.10^5
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: from 60 to 120 µE x m-2 x s-1, or an equivalent range of 4000 to 8000 lux, in the spectral range 400 to 700 nm.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: particle counter (Z2, Beckmann Coulter)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 50 and 100 mg/L
- Range finding study: yes
- Test concentrations: 100 mg/L

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Details on results:

No toxic effects against algae (Desmodesmus suspicatus) were observed at the test concentration of 100 mg/L under exposure conditions.

Reported statistics and error estimates:

All calculations were carried out using the statistics programme ToxRatPro Version 2.10 (released 2010-09-10).
Growth curves were plotted for each test concentration and the control.

Validity criteria fulfilled:

yes

Conclusions:

No toxic effects against algae (Desmodesmus subspicatus) were observed at the test item concentration of 100 mg/L after 72 h of exposure, under the exposure conditions laid out in the EU method C.3 and OECD TG 201.

Executive summary:

The adverse effects of Lithium titanate on the growth rate and the yield of the planktonic freshwater algal species Desmodesmus subspicatus were assessed over several generations. The study was conducted in accordance with the EU Method C.3, which is equivalent to OECD Guideline for Testing of Chemicals No. 201. 

Exponentially growing algal cells were exposed for a period of 72 hours to a range of concentrations, nominally 50 and 100 mg/L, of Lithium titanate dissolved in dilution water.

No toxic effects against algae (Desmodesmus suspicatus) were observed at the test concentration of 100 mg/L after 72 h of exposure. 

Description of key information

No toxic effects against algae were observed at the test concentration of 100 mg/L under exposure conditions.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

100 mg/L

Additional information

The EC50 and EC10 values should be read as ">100 mg/L". 

The NOEC value should be read as ">=100 mg/L".