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Long-term toxicity to aquatic invertebrates

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The conduct of a chronic toxicity study on Daphnia with the target substance titanium oxide sulphate itself is being waived, as the substance is highly unstable in water and produces insoluble titanium dioxide after rapid hydrolysis. Based on the information available it can be concluded that neither target compound titanium oxide sulphate nor the final hydrolysis transformation products titanium dioxide and sulphuric acid (after being neutralised) exhibit chronic toxicity to aquatic invertebrates.

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The conduct of a chronic toxicity study on aquatic invertebrates with the target substance itself is being waived, as the substance is highly unstable in water and produces insoluble oxide after rapid hydrolysis. Thus the aquatic hazard assessment is to be based on the transformation products. As pH effects are not true toxic effects and not relevant for assessment and as the sulphates can occur at rather high natural background concentrations, the assessment shall be based on titanium dioxide.

The assumption of absent chronic invertebrate toxicity of titanium dioxide is supported by the low bioaccumulation tendency (Frederici et al 2007), the absence of acute toxicity at high loading rates, and by the experimental data of Beim et al (1982). The experiment is not sufficiently documented but it evidences the absence of chronic effect to reproduction of daphnids up to 100 mg/L loading rate. This is five orders of magnitude higher than the water solubility of the test item titanium dioxide. Finally, titanium dioxide is virtually insoluble in water (< 1 µg/L).

It is concluded that final hydrolysis transformation product titanium dioxide does not exhibit effects at the level of its water solubility in addition with suspended microdisperse matter in excess, even if ingested. Concerning the target compound titanium oxysulfate itself, the increase of acidity caused by the rapid hydrolysis reaction to form the other final hydrolysis product sulphuric acid is of no relevance for environmental risk assessment under REACH. Within the environmentally relevant pH range sulfuric acid species are being neutralised and thus rendered harmless to biota.