Niobium doped titanium dioxide

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:

2019-04-19 to 2019-05-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

Adopted 13, April 2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

For the analytical measurement, samples were directly taken after each fresh medium preparation and for the determination of the test material concentration during the exposure period; samples were also taken at the end of the exposure period.

Vehicle:

yes

Remarks:

Reconstituted water

Details on test solutions:

A stock preparation with a test item concentration of 100 mg/L was freshly prepared. For that purpose, the test item was weighed in a calibrated flask and vehicle was added. The preparation was stirred with a magnetic stirrer for 24 hours. Then, the formulation was passed through a filter membrane (pore size: 0.2 µn). The filtrate was used for the study. The pH was not adjusted.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia Magna
- Strain/clone: Straus
- Age at study initiation: not older 24 h
- Source: IBACON GmbH (Roßdorf, Germany)
- Feeding during test: no
ACCLIMATION
- Acclimation period: no
- Breeding conditions: same as test
- Type and amount of food: unicellular green algae
- Feeding frequency: ad libitum, three times per week
- Health during acclimation: no mortality observed

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

252 - 256 CaCO3/L

Test temperature:

20.9 - 21.6°C

pH:

7.74 - 7.90

Dissolved oxygen:

8.08 - 8.22 mg/L

Conductivity:

672 - 680 µS/cm

Nominal and measured concentrations:

Nominal measured: 100 mg/L
Measured: below LOQ

Details on test conditions:

TEST SYSTEM
- Test vessel: glass vessel
- Type: open
- Material, size, fill volume: glass, 20 mL, 20 mL
- Volume of solution: 20 mL
- Aeration: no
- Renewal rate of test solution: every 24 hours
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
TEST MEDIUM / WATER PARAMETERS
- Preparation of dilution water: the water was composited according to ELENDT M4 (1990)
OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hour light and 8 hour dark regime
- Light intensity: 589 – 596 Lux

EFFECT PARAMETERS MEASURED
The mobility was determined after 24 and 48 hours
RANGE-FINDING STUDY
- Test concentrations: 100 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: no
- Observations on body length and weight: no
- Other biological observations: no
- Mortality of control: no
- Other adverse effects control: no
- Immobilisation of control: no
- Abnormal responses: no
- Any observations that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no
No effect on the mobility of the daphnia was observed at a nominal concentration of 100 mg/L.

Table 1: Immobilization of Daphnia magna

Nominal Test Item Concentration [mg/L]	Number of daphnids immobilized / exposed		% of daphnids immobilized
	24 hours	48 hours	24 hours	48 hours
0	0/20	0/20	0%	0%
100	0/20	0/20	0%	0%

Table 2: EC₅₀ values

Test Duration	EC50
24h	>100 mg/L (nominal concentration)
48h	>100 mg/L (nominal concentration)

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions according to OECD 202 of the present study, an aqueous solution of nominal concentration of 100 mg/L of the test item revealed no toxicity to daphnids. The 48h EC50 was >100 mg/L (nominal concentration) and, thus, exceeded the maximum water solubility of the test material.

Executive summary:

The objective of this aquatic toxicity study was to determine the effect of the test item on the mobility of Daphnia magna according to OECD 202. For this purpose, juvenile daphnids, aged less than 24 hours old at the start of the study, were exposed for a period of 48 hours to one concentration (limit test) of the test item. Immobilization was recorded at 24 and 48 hours and compared with control values. The results were analyzed in order to calculate the EC₅₀ at 24h and 48h. The study was performed following a semi-static test design, i.e. the test item preparations (test item group) and the vehicle (control group) were renewed after 24 hours. Samples of the test medium and control medium were taken directly and 24h after each preparation for further analysis of the test item concentration. The purpose of the analytical part of this study was to verify the concentrations of the test item in the test medium. Therefore, two components of the test item (Niobium, Titanium) were analysed using HR-ICP-Mass Spectrometry. The chemical analysis of the different components of the test item was performed in the test media samples and in the control samples. Two components, i.e. Niobium (Nb) and Titanium (Ti) were analyzed via HR-ICP-Mass Spectrometry. No component of the test item was detected in the control medium. Therefore, it was confirmed that daphnia in the control group were not exposed to the test item. All validity criteria were met. No effect on the mobility of the daphnia was observed at a nominal concentration of 100 mg/L. Under the conditions of the present study, an aqueous solution of nominal concentration of 100 mg/L of the test item revealed no toxicity to daphnids. The 48h EC₅₀ was >100 mg/L (nominal concentration) and, thus, exceeded the maximum water solubility of the test material.

Description of key information

Under the conditions according to OECD 202 of the present study, an aqueous solution of nominal concentration of 100 mg/L of the test item revealed no toxicity to daphnids. The 48h EC₅₀ was >100 mg/L (nominal concentration) and, thus, exceeded the maximum water solubility of the test material.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

100 mg/L

Additional information

The objective of this aquatic toxicity study was to determine the effect of the test item on the mobility of Daphnia magna according to OECD 202. For this purpose, juvenile daphnids, aged less than 24 hours old at the start of the study, were exposed for a period of 48 hours to one concentration (limit test) of the test item. Immobilization was recorded at 24 and 48 hours and compared with control values. The results were analyzed in order to calculate the EC₅₀ at 24h and 48h. The study was performed following a semi-static test design, i.e. the test item preparations (test item group) and the vehicle (control group) were renewed after 24 hours. Samples of the test medium and control medium were taken directly and 24h after each preparation for further analysis of the test item concentration. The purpose of the analytical part of this study was to verify the concentrations of the test item in the test medium. Therefore, two components of the test item (Niobium, Titanium) were analysed using HR-ICP-Mass Spectrometry. The chemical analysis of the different components of the test item was performed in the test media samples and in the control samples. Two components, i.e. Niobium (Nb) and Titanium (Ti) were analyzed via HR-ICP-Mass Spectrometry. No component of the test item was detected in the control medium. Therefore, it was confirmed that daphnia in the control group were not exposed to the test item. All validity criteria were met. No effect on the mobility of the daphnia was observed at a nominal concentration of 100 mg/L. Under the conditions of the present study, an aqueous solution of nominal concentration of 100 mg/L of the test item revealed no toxicity to daphnids. The 48h EC₅₀ was >100 mg/L (nominal concentration) and, thus, exceeded the maximum water solubility of the test material.