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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

Titanium carbide was not tested for short-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 acute and prolonged toxicity tests with titanium dioxide; a definitive LC50 could not be determined.

Key value for chemical safety assessment

Additional information

Wahrheit et al. (2007) tested fine TiO2 (380 nm) and ultrafine TiO2 (140 nm) using rainbow trout as test organisms according to the protocol of OECD guideline 203. Fish were exposed for 96 h at nominal test concentrations up to 100 mg TiO2/L (both particle sizes). The LC50 values for fine and ultrafine TiO2 for rainbow trout were determined to be > 100 mg/L.

This result is further supported by Griffitt et al. (2008) who did not observe toxic effects to adult female zebrafish when exposed at nominal concentrations up to 10 mg/L TiO2 for 48 h.

In addition, TiO2 did not exhibit toxic effects in rainbow trout when fish were exposed for 14 days at concentrations up to 1 mg/L (Frederici et al., 2007).

Based on 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 high 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 short-term toxic effects to fish are not expected to arise from TiC.