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Environmental fate & pathways

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Testing of biodegradability in water is not scientifically justified as titanium tetra(octanolate), branched and linear is hydrolytically unstable. Key study on hydrolysis demonstrates that a complete hydrolysis (half-life < 10 minutes) will take place with no significant reaction products other than octyl alcohol isomers (Exxal 8; alcohols, C7-9-iso, C8-rich) and hydrated titanium dioxide (Brekelmans M.J.C. 2013).

In addition, biodegradability testing is not necessary to be tested for this substance as all the decomposition products have been identified. The most relevant degradation product Exxal 8 is also known to be readily biodegradable (> 80 % at 28-d biodegradation, Exxon Mobil 1997). Exxal 8 is not classified as hazardous to aquatic environment and has no adsorption or bioaccumulation potential (low log Kow value is 3.2 and BCF fish 15.2 L/kg). The other non-hazardous degradation product (hydrated TiO2) of this substance is inorganic and insoluble and therefore not relevant to be considered further in CSA. Ti compounds are not expected to bioconcentrate in soils, sediments or aquatic organisms.

The direct exposure of the aquatic compartment is unlikely (see sections 9&10 of CSR). Since the target substance is hydrolytically unstable, use of water is avoided in the use applications; and there is no emission to a sewage treatment plant (STP). Discharge to STP is relevant only in one use application when the target substance is used as a catalyst in industrial esterification processes. In this use application, water is used to remove the catalyst from the process. The discharge to STP is related to the degradation products of this substance as the hydrolysis will take place, and Exxal 8 and TiO2 are released to water compartment.

Therefore, it is justified to use the information on the ready biodegradability of the main degradation product (Exxal 8) in the exposure assessment when relevant (see sections 9&10 of the CSR).

CSA does not either indicate the need to investigate further the biodegradation in sediments or soil. Local point sources can be disregarded as there are no sources that emit directly to the terrestrial compartment. Spreading of sewage sludge is not likely as use of water is avoided in use applications because of high reactivity of the substance. In esterification application, the possible spreading of STP sewage sludge as fertilizer to soil cause a low hazard to soil organisms as the degradation products are readily biodegradable (Exxal 8). Indirect emissions to environment are occuring only via atmospheric deposits (sections 9&10 of the CSR).

As the rapid hydrolysis is the driving force for the fate and pathways of this substance, this abiotic degradation can be used to demonstrate fast degradation for the purposes of C&L.

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