Registration Dossier

Ecotoxicological information

Sediment toxicity

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

No experimental data evaluating the toxicity to sediment organisms is available for 2-ethylhexyl benzoate (CAS No. 5444-75-4).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. This is confirmed by the outcome of the risk assessment (CSR 2018), that shows RCR values < 0.1 for sediment exposure. Furthermore, the substance is not toxic to aquatic organisms up to the limit of water solubility. In addition, available data indicate that 2-ethylhexyl benzoate is not bioaccumulative. Based on the available information, toxicity to sediment organisms is not expected to be of concern.

Key value for chemical safety assessment

Additional information

No experimental data evaluating the toxicity to sediment organisms is available for 2-ethylhexyl benzoate (CAS No. 5444-75-4). Only negligible releases into surface waters from sewage treatment plants are expected to take place due to:

a) the ready biodegradability (77% CO2 evolution in 28 days; Dickinson, 2008) and

b) the high adsorption properties of this substance, resulting in an effective removal in sewage treatment plants.

The substance exhibits a log Koc value of 4.07 and is poorly water soluble (0.4 mg/L).

The Guidance on information requirements and chemical safety assessment, Chapter R7.B (ECHA, 2017) 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, 2008)) and the rest will be extensively biodegraded (due to ready biodegradability). Therefore chronic exposure of sediment organisms is expected to be very low. This confirmed by the exposure calculations in the current risk assessment (CSR 2018). The risk assessment uses the equilibrium partitioning method to calculate the PNEC for toxicity towards sediment organisms. The outcome shows RCR values for risks towards sediment organisms < 0.1 for all exposure scenarios (these values are considered worst case as the risk characterisation ratio for sediment is multiplied by a factor of 10 to account for uncertainty due to the potential for adsorption based on the fact that the logKow is >5).

For sediment organisms rapid metabolism of 2-ethylhexyl benzoate is expected. After absorption, the substance is expected to be enzymatically hydrolysed in vivo by the enzyme carboxylesterase, yielding the corresponding alcohol and benzoic acid (Jones, 1956). Both hydrolysis products are supposed to be satisfactory metabolized in aquatic organisms. Therefore, no potential for bioaccumulation is to be expected.  

The substance is not toxic to aquatic organisms up to the limit of water solubility. The performance of a long-term toxicity study to aquatic invertebrates has not been possible due to technical difficulties and as indicated above the exposure of the sediment is expected to be very low, therefore a study investigating toxicity of the substance towards sediment organisms is omitted.