Titanium tetra(octanolate), branched and linear

Endpoint summary

Additional information

Titanium tetra(octanolate), branched and linear is an organometallic substance which is hydrolytically unstable. The hydrolytic stability was tested in buffered aqueous solutions at pH 4.0, 7.0, and 9.0 at 25°C for 40 minutes (Brekelmans M.J.C. 2013). Based on the results, half-life of substance was less than 5 minutes at pH 4, and less than 10 minutes at pH 7 and 9, respectively. The progress of the hydrolysis was followed by monitoring octyl alcohol isomers (Exxal 8; alcohols, C7-9-iso, C8-rich) used in manufacturing of this substance).

Titanium is a solid precipitate of the substance present as hydrated titanium dioxide in water after hydrolysis. This decomposition product is not classified hazardous to human health or the environment. Furthermore, Ti compounds are not expected to bioconcentrate in soils, sediments or aquatic organisms (WHO 1982). As an insoluble precipitate, it is also lacking bioavailability, and therefore not relevant to be considered further in CSA.

Because of the rapid abiotic degradation, water solubility, biodegradation and partition coefficient (Kow) cannot be determined for the substance itself. In addition, the intrinsic properties of aquatic toxicity are related to the main degradation product (Exxal 8) of this substance. This was demonstrated by the aquatic toxicity studies (daphnia and algae) conducted for this substance according to the OECD guidelines and in accordance with GLP (Tobor-Kapłon M.A. 2013). The test item hydrolyzed immediately in aqueous test media releasing mixture of octyl alcohol isomers (Exxal 8; alcohols, C7-9-iso, C8-rich) with the hydrated titanium oxide precipitating out of the test solution. Due to the rapid hydrolysis, it was considered that any toxicity would be due to the presence of the solvent (Exxal 8) and not the parent test item.

Therefore, the toxicity to the freshwater invertebrates and algae were investigated based on the measured octyl alcohol isomers concentrations only. Based on these study results conducted for the substance, the short-term toxicity testing to other organisms (fish and micro-organisms) was considered scientifically unjustified. Instead the read-across data from the main degradation product (mixture of octyl alcohol isomers; Exxal 8) was used as a key value in CSA (see section 7.1 of CSR). The toxicity results of the target substance and the decomposition product do not indicate the need to classify this substance as hazardous to the environment.

As the rapid hydrolysis is the driving force for the fate and pathways of this substance, the abiotic degradation can be used to demonstrate fast degradation for this substance. This is justified as all decomposition products have been identified. The most relevant degradation product (Exxal 8) is readily biodegradable (> 80 % at 28-d biodegradation, ExxonMobil 1997) and not classified as hazardous to the environment. The long-term aquatic toxicity was not necessary to be further considered for the target substance based on the short-term toxicity test results and ready biodegradability of the degradation product (Exxal 8).

Based on the composition of titanium tetra(octanolate), branched and linear and the properties of the main degradation product, this titanate in the atmosphere has no potential for stratospheric ozone depletion for structural reasons. It does not contain any halogens. Therefore there is no reason for any hazard classification under the CLP regulation 1272/2008 for atmospheric environment (the ozone layer).

The transport and distribution of titanium tetra(octanolate), branched and linear was evaluated based on its reactivity. Because of rapid hydrolysis, most of the physical chemical properties of the target substance are not technically feasible to determine. Therefore, the fate and pathways are related to the organic degradation product. The vapor pressure of titanium tetra(octanolate), branched and linear cannot be determined as it decomposes during testing (OECD 104, Brekelmans M.J.C. 2013). If released to air, this substance will release octyl alcohols. The Henry's Law constant of 0.26 Pa m³/mol at 20 deg. C for Exxal 8 (alcohols, C7-9-iso, C8-rich) indicates that volatilization from water is expected to occur at a slow rate.

If released to soil, because of soil moisture this titanate will decompose releasing Exxal 8 and hydrated titanium dioxide. The adsorption coefficient of Exxal 8 (Koc value of 32.2 L/kg), estimated by using KOCWIN v.2.00 is used in CSA for the target substance (US EPA 2012). It is expected to have high mobility based upon an estimated Koc. In addition, the water solubility of Exxal 8 (soluble in water, Meylan .et al 1995) indicates high mobility in soil. The Mackay Level III equilibrium model estimates that the decomposition product (Exxal 8; alcohols, C7-9-iso, C8-rich) of the target substance will partition largely to the water compartment (approximately 96.6%), followed by the partitioning to sediment (approximately 3.3%), soil (approximately 0.03%), and air (0.03%) compartments. Biodegradation is expected to be an important fate process.

Based on the CSA, this substance is not fulfilling the criteria to be classified as hazardous to the environment or as a PBT or vPvB substance. Thus, CSA indicates that further testing of long-term aquatic effects or terrestrial toxicity testing is unnecessary. In addition, testing is scientifically unjustified as the direct exposure to aquatic or terrestrial compartment is unlikely based on the exposure scenarios (see section 9&10 of CSR). Since the target substance is hydrolytically unstable, use of water is avoided in the use applications, there are no emissions 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. The possible spreading of STP sewage sludge as fertilizer to soil is expected to cause low hazard to soil organisms as the degradation products are readily biodegradable (Exxal 8) and/or non-toxic to environment. Indirect emissions to environment are occuring only via atmospheric deposits.

There are all together six different organometallic titanates from the same manufacturer which are registered at the same tonnage band. As all these titanates are hydrolytically unstable substances and they have structural similarities, group categories were formed. Because of behavioral similarities some properties of these titanates are evaluated by using read-across data from the category members as well as from the degradation products. The category and read-across justifications with data matrices are presented in the Annexes of this CSR.

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