Titanium carbide

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

fish short-term toxicity test on embryo and sac-fry stages

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Justification for read-across: Due to lower transformation/dissolution results for titanium carbide (the target substance) than titanium dioxide (the source substance), the resulting toxicity potential would also be expected to be lower, so read-across is appropriate. Therefore, the dose descriptors are expected to be sufficiently higher for the target substance, and read-across to the source chemical is adequately protective. For more details refer to the attached description of the read-across approach (see IUCLID section 13.2).

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

reference to same study

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Reported statistics and error estimates:

LC50 values were calculated using the trimmed Spearman-Karber method.

Validity criteria fulfilled:

not specified

Conclusions:

No mortality could be observed in juveniles (fry < 24 h) when exposed to TiO2 nanoparticles in concentrations up to 10 mg/L for 48 h.

Executive summary:

The 48 hr toxicity of TiO₂ nanoparticles to juveniles (sac fry stage < 24 h) of Danio rerio (zebrafish) was studied under static conditions. Embryos were exposed to TiO₂ at concentrations ranging between 0 (control) and 10 mg/L nominal concentration. Mortality was observed every 12h. 

 

The 48 hour LC₅₀ was > 10 mg/L (nominal concentration).

 

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

Reference 2

Endpoint:

fish short-term toxicity test on embryo and sac-fry stages

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

ASTM Guideline study (similar to OECD 212) without detailed documentation.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: other guideline: American Society for Testing and Materials: Standard guide for conducting acute toxicity tests on test materials with fishes, macro invertebrates and amphibians

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 212 (Fish, Short-term Toxicity Test on Embryo and Sac-Fry Stages)

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Dilution water was dechlorinated municipal water, moderately hard.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: zebrafish (wild-type)
- Source: Ekk-Will, Gibsonton, FL, USA
- Maintenance: at the Aquatic Toxicology Laboratory, University of Florida
- Age at study initiation (mean and range, SD): fry stage (< 24 h)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

142±2 mg CacO3/l

Test temperature:

Not reported

pH:

8.2±1

Dissolved oxygen:

8.5-8.9 mg/l

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal: up to 10 mg/l

Details on test conditions:

TEST SYSTEM FOR JUVENILE FISH (fry, < 24 h)
- Test vessel: exposure in 12-well plates
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 4 ml
- Aeration: no
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

TEST MEDIUM / WATER PARAMETERS
- Filtration: 0.45 µm pore size

OTHER TEST CONDITIONS: no data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mortality
> Survival of juvenile fish was assessed by direct observation under light microscopy (death = lack of a visible heartbeat for 30 s and lack of response to physical prodding)

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Reported statistics and error estimates:

LC50 values were calculated using the trimmed Spearman-Karber method.

Validity criteria fulfilled:

not specified

Conclusions:

No mortality could be observed in juveniles (fry < 24 h) when exposed to TiO2 nanoparticles in concentrations up to 10 mg/L for 48 h.

Executive summary:

The 48 hr toxicity of TiO2 nanoparticles to juveniles (sac fry stage < 24 h) of Danio rerio (zebrafish) was studied under static conditions. Embryos were exposed to TiO2 at concentrations ranging between 0 (control) and 10 mg/L nominal concentration. Mortality was observed every 12h. 

The 48 hour LC₅₀was > 10 mg/L (nominal concentration).

Description of key information

Titanium carbide was not tested for long-term toxicity to fish, and read-across to titanium dioxide was used for this endpoint. 
No deaths were observed at saturation concentration under exposure conditions in a toxicity test on embryo and sac-fry stages of Danio rerio with titanium dioxide. The NOEC is 10 mg TiO2/L.

Additional information

Griffitt et al. (2008) conducted a test with Danio rerio (zebrafish) similar to OECD Guideline 212 (Fish, Short-term Toxicity Test on Embryo and Sac-Fry Stages). This test is considered relevant in the evaluation of chronic toxicity to fish (see ECHA Guidance R.7b).

Sac fry stages of zebrafish were exposed to TiO2 nanoparticles for 48 h at concentrations up to 10 mg/L (nominal). Mortality, evaluated by direct observation under light microscopy (death = lack of a visible heartbeat for 30 s and lack of response to physical prodding), was assessed every 12h. No mortality was observed at all concentrations tested.

 

Due to lower transformation/dissolution results for titanium carbide (the target substance) than titanium dioxide (the source substance), the resulting toxicity potential would also be expected to be lower. Therefore, the dose descriptors are expected to be sufficiently higher for the target substance, and read-across to the source chemical is adequately protective (for more details refer to the attached description of the read-across approach). In fact, (eco-) toxicologically relevant release of Ti ions from titanium carbide is not expected as the concentration of soluble Ti ions was below the method detection limit (< 0.4 µg/L) in the T/D test. Thus, TiC in considered to be practically insoluble, hence release of Ti ions to any ecotoxicologically relevant extent (and potential subsequent formation of soluble and/or insoluble Ti compounds) is not expected. Therefore, any long-term toxic effects for fish are not expected to arise from TiC.