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Sediment toxicity

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Endpoint:
sediment toxicity: long-term
Data waiving:
other justification
Justification for data waiving:
other:

Description of key information

Toxicity to sediment organisms is negligible.

Key value for chemical safety assessment

Additional information

No experimental data evaluating the toxicity to sediment organisms is available for Propane-1,2,3-triyl 2-ethylhexanoate (CAS No. 7360-38-5). Only negligible releases into surface waters from sewage treatment plants are expected to take place due to: a) the ready biodegradability and b) the high adsorption properties of this substance, resulting in an effective removal in sewage treatment plants. Therefore chronic exposure of sediment organisms is unlikely. In addition, available data indicate, that Propane-1,2,3-triyl 2-ethylhexanoate is not bioaccumulative. Furthermore, the environmental exposure assessment for the substance indicates no risk for the sediment compartment (all RCR< 1; please refer to Chapter 9 and 10 of the Chemical Safety Report for detailed information). Based on the available information, toxicity to sediment organisms is not expected to be of concern.

Propane-1,2,3-triyl 2-ethylhexanoate (CAS No. 7360-38-5) is readily biodegradable (85% O2 consumption in 28 days; METI, 2002). According to the Guidance on information requirements and chemical safety assessment, Chapter R.7b, readily biodegradable substances can be expected to undergo rapid and ultimate degradation in most environments, including biological Sewage Treatment Plants (STPs) (ECHA, 2017b). Therefore, after passing through conventional STPs, only low concentrations of these substances are likely to be (if at all) released into the environment.

Furthermore, the substance exhibits a log Koc value of 6.28 and is poorly water soluble (< 0.05 mg/L measured in aqua dest). The Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2017b) states that once insoluble chemicals enter a standard STP, they will be extensively removed in the primary settling tank and fat trap and thus, only limited amounts will get in contact with activated sludge organisms. Nevertheless, once this contact takes place, these substances are expected to be removed from the water column to a significant degree by adsorption to sewage sludge (Guidance on information requirements and chemical safety assessment, Chapter R.7a, (ECHA, 2017a) and the rest will be extensively biodegraded (due to ready biodegradability).Thus, discharged concentrations of these substances into the aqueous/sediment compartment are likely to be negligible. Considering this one can assume that the availability of Propane-1,2,3-triyl 2-ethylhexanoate in the sediment environment is generally very low, which reduces the probability of chronic exposure of sediment organisms in general. This is underlined with the environmental exposure assessment for the substance indicates no risk for the sediment compartment (all RCR< 1; please refer to Chapter 9 and 10 of the Chemical Safety Report for detailed information). 

Due to its readily biodegradable nature, extensive degradation of this substance in conventional STPs will take place and only low concentrations are expected to be released (if at all) into the environment. Once present in the aquatic compartment, further biodegradation will occur and, due to the high log Kow, low water solubility and high adsorption potential, Propane-1,2,3-triyl 2-ethylhexanoate will be bioavailable to sediment organisms mainly via feed and contact with suspended organic particles.The supporting BCF/BAF values estimated with the BCFBAF v3.01 program, Arnot-Gobas model including biotransformation, indicate that this substance will not be bioaccumulative (all well below 2000 L/kg) underlined with the environmental exposure assessment for the sediment compartment (all RCR< 1; please refer to Chapter 9 and 10 of the Chemical Safety Report for detailed information). According to Annex IX, column 2 of Regulation (EC) No 1907/2006, testing with sediment organisms does not need to be conducted as the Chemical Safety Assessment does not indicate a need for further investigations. According to Annex XI, Section 3 of Regulation (EC) No 1907/2006 toxicity tests on sediment organisms are considered not necessary.

Therefore, Propane-1,2,3-triyl 2-ethylhexanoate is unlikely to pose a risk for sediment organisms in general and testing is thus omitted.