Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Biodegradation studies in water, sediment and soil are not required for inorganic substances, such as titanium dioxide.

According to Annex IX, Column 2 of Regulation (EC) 1907/2006, "Further biotic degradation testing shall be proposed by the registrant if the chemical safety assessment according to Annex I indicates the need to investigate further the degradation of the substance and its degradation products. The choice of the appropriate test(s) depends on the results of the chemical safety assessment."

In the case of inorganic elements, the chemical safety assessment is generally based on total elemental metal concentrations, regardless of their (pH-dependent) speciation in the environment. Therefore, physicochemical processes such as degradation or transformation by reaction with water are not relevant. Depending on the prevailing environmental conditions, different Ti species may form, but the chemical assessment will not differentiate between the different Ti species. This total, elemental-based assessment (pooling all speciation forms together) applies a worst-case approach to the chemical assessment. Further, biodegradation reactions are not relevant for metals and metal compounds that are not biodegradable, including titanium dioxide.

In conclusion, (bio)degradation is an irrelevant process for inorganic substances that are assessed on an elemental basis, including titanium dioxide.