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Ecotoxicological information

Long-term toxicity to fish

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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.

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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.