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Titanium oxide sulphate rapidly hydrolyses in water, resulting in the formation of titanium dioxide and causing an increase in acidity via formation of sulphuric acid. Titanium dioxide is very poorly soluble in water, excess titanium dioxide will be present as insoluble matter.

Toxicity to fish, Daphnia and algae toxicity (short-term and long-term):

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.

Toxicity to microorganisms:

As hydrolysis of one mol of target substance titanium oxide sulphate results in one mol sulphuric acid, and as only the first protolysis step shall be considered, this hydrolysis reaction produces approximately one mol hydronium ions. The EC50of target compound titanium oxide sulphate to activated sludge microorganisms therefore would be assigned to 6.3 µmol/L. Based on the titanium oxide sulphate molecular weight of 159.93 g/mol, this corresponds to a mass concentration of 1.0 mg/L. The result suggests strong pH related effects resulting from the hydrolysis of target compound titanium oxide sulphate. In conclusion the toxicity of the hydrolysis products of titanium oxide sulphate are considered not toxic to aquatic micro-organisms and no threshold level is derived.