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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Testing is not scientifically justified as this substance is hydrolytically unstable. Therefore, the results (72-h EC50 and NOEC) of the main decomposition product 2-ethylhexanol is used as a key value.

Key value for chemical safety assessment

EC50 for freshwater algae:
16.6 mg/L
EC10 or NOEC for freshwater algae:
2 mg/L

Additional information

When this substance comes in contact with water or moisture, a complete hydrolysis will take place with no significant reaction products other than 2-ethylhexanol and hydrated titanium dioxide (half-life < 10 minutes, Brekelmans M.J.C. 2013). The organic decomposition product 2 -ethylhexanol is readily biodegradable and not persistent (log Kow value 2.9 < 4). Therefore, the testing was considered unnecessary. The CSA indicates that toxicity of this substance is similar to the main degradation product 2-ethylhexanol based on the weight of evidence which uses the studies conducted for the analogue category member and the degradation product (2 -ethylhexanol).

Key studies (short-term toxicity to daphnia and algae) conducted for the analogue category member (titanium tetra(octanolate), branched and linear, CAS 68526 -83 -0) justify that these organometallic titanates hydrolyse during toxicity testing and the aquatic toxicity is similar to the alcohol released in water. Category and read-across justifications are presented in the annexes of the CSR.

This read-across substance is an analogue substance grouped together with the target substance into the category of highly water reactive titanates. It contains commercial solvent (Alcohols C7 -9-iso, C8-rich, CAS no 68526 -83 -0). This solvent contains 93 % of isooctanol being also an analogue substance with 2-ethylhexanol; an isomer of octyl alcohol.

The 72-h EC50 (growth rate) to Pseudokirchnerella subcapitata measured by using OECD 201 in accordance with GLP was conducted for the analogue category member. As the test substance hydrolysed during testing releasing alcohol and hydrated titanium dioxide in water, the test concentrations were measured based on the released octyl alcohol isomers. Test substance reduced growth rate at a TWA concentration of 20 mg octyl alcohol isomers per litre. The EC50 for growth rate reduction (ERC50: 0-72h) was beyond the range tested. The NOEC for growth rate reduction was 6.7 mg/l based on a TWA concentration of octyl alcohol isomers, which represents 32 % of a filtrate prepared at 100 mg titanium tetra(octanolate), branched and linear per litre.

In addition, a reliable 72-h EC50 (growth rate) (72 h) of 2-ethylhexanol to Scenedesmus subspicatus (new name: Desmodesmus subspicatus) is 16.6 mg/L, and the NOEC is 2.0 mg/L. This study test was conducted according EEC 84/449, C.2 ( i.e. similar to OECD test guideline 201) in accordance with GLP (Scholz 1991).

Based on the weight of evidence approach, the results of the analogue category member and the degradation product are relatively similar. The key NOEC and EC50-values for CSA are obtained from the lowest values i.e. the values of 2 -ethylhexanol.