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Sediment toxicity

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Description of key information

A low toxicity of the test substance to sediment organisms is indicated (LC50(10d) > 1439 mg/kg dw).

Key value for chemical safety assessment

Additional information

No studies on long-term sediment toxicity are available for this substance. Due to the high Koc a considerable adsorption to sediment and soil is indicated. However, all members of the category have been shown to be readily biodegradable, hence it can be assumed that they will be completely biologically degraded within the sediment transport process. Therefore, no chronic exposure of sediment dwelling organisms is expected. Furthermore, two valid short term toxicity tests on the marine sediment dwelling amphipod Corophium volutator are available within this category, indicating no toxicity. In addition, Fatty acid esters are readily metabolised in Fatty acids and alcohols. These components occur in sediment and soils naturally, are part of physiological pathways and can be used as energy source. The enzyme carboxylesterase is omnipresent in the environment, readily degrading the test substances of this category. Thus, toxic effects caused by the metabolites of fatty acid esters are implausible.

 

In conclusion, due to a) the observed absence of toxicological effects on aquatic and sediment organisms, b) the lack of chronic exposure and c) the, acknowledged metabolisation of fatty acid esters, toxic effects on sediment dwelling invertebrates can be excluded.

 

Two studies on Corophium volutator served as indicator for the low toxicity of the category members on sediment dwelling organisms. In a GLP-study according to OSPARCOM standards, Fatty acids, C16-18 and C18 unsatd., 2-ethylhexyl esters (CAS 85049-37-2) was tested. Corophium volutator was held in 1 L beakers with natural (filtered) sediment and artificial seawater in nominal concentrations of 15 to 13932 mg/kg dw (Hudson 2000). The resulting LC50(10d) was >1439 mg/kg dw. A second study was conducted under similar conditions using Fatty acids, C8-16, 2-ethylhexyl esters (CAS 138500-37-2) as test substance. Nominal concentrations of 1000 to 10000 mg/kg dw were studied resulting in a LC50(10d) of >10000 mg/kg dw (Gibson 1999).