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Long-term toxicity to fish

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Description of key information

No experimental data on long-term toxicity to fish are available for 2-ethylhexyl benzoate (CAS 5444-75-7). The chemical safety assessment according to Annex I of Regulation (EC) 1907/2006 does not indicate the need to investigate further the long-term toxicity to fish. Thus, in accordance to Annex IX, column 2, no further long-term toxicity test to fish is proposed.

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Additional information

In the short-term toxicity tests with the substance, THF was used as a solubilising agent to prevent formation of non-suspended precipitates. This was not very successful regarding maintenance of the test concentrations. In the daphnia study the concentrations, though initially within the expected ranges, were not properly maintained over 24 hour periods (semi-static design). In the acute fish study performed according to a flow-through design, a film was observed on the surface of the water, but the measured concentrations remained stable. With algae, no substance was measured at the end of the exposure period (72 h), although starting concentrations were adequate. No definitive conclusion can be drawn on the reasons for the dissipation of the substance, but biodegradation and adsorption are probable. The substance is readily biodegradable, but given that degradation over 1 day was 30% and over 3 days was 50%, the dissipation of the substance cannot wholly be attributed to biodegradation. The logPow of the substance is 6.2. which may lead to some sorption. The substance is hydrolytically stable.

Taking into account the above mentioned difficulties, an attempt was done to reach concentrations that would be stable over 24 hours to be used in a daphnia reproduction study (daily renewal of the medium was foreseen) as included in the testing proposal approved by ECHA (TPE-D-21114346840 -50 -01/F). A large number of pre-tests with different dispersants was performed (see Envigo 2018). In these attempts either non-stable concentrations were found or toxicity was observed that could be related to the dispersant used. Therefore it was concluded that the daphnia reproduction study was technically unfeasible and was not performed.

There is no sign that fish are more sensitive than daphnia in the short term tests and it is expected that a long-term test with fish will give the same technical difficulties as the daphnia study did. It is not expected that 2-ethylhexyl benzoate will show any chronic toxicity to fish up to the limit of water solubility. Hence due to animal welfare reasons and to avoid unnecessary vertebrate tests, no further long-term test with fish is proposed for this substance.