Fatty acids, C5-9, hexaesters with dipentaerythritol

Endpoint summary

Additional information

The toxicity ofcarboxylic acids, C5-9, hexaesters with dipentaerythritol (CAS 67762-52-1) to terrestrial organisms was tested in one available long-term toxicity test on earthworms. Eisenia fetida was exposed to the substance in artificial soil according the specifications given in OECD guideline 222 under GLP conditions (Eisner, 2013). Nominal concentrations of 62.5, 125, 250, 500 and 1000 mg/kg dw were tested. The mortality and growth of adult earthworms was determined after 28 days. Another 28 days later the reproduction rate was assessed. Adverse effects of the substance were not observed and thus a NOEC (56 d) ≥ 1000 mg/kg was determined based on reproduction. Studies on other terrestrial organisms are not available but a toxicity of the substance to terrestrial organisms is considered to be unlikely.

The test substance is characterized by a log Koc > 5 indicating a high potential for adsorption to soil particles. Tests with soil-dwelling organisms that feed on soil particles are therefore most relevant for the evaluation of soil toxicity. In the absence of a clear indication of selective toxicity, an invertebrate (earthworm or collembolan) test is preferred, as outlined in ECHA guidance section R.7.11.5.3 (ECHA, 2012). Chronic soil macroorganism data are available resulting in no effects on reproduction for earthworms were observed (NOEC (56 d) ≥ 1000 mg/kg soil dw). Due to the low water solubility (< 0.05 mg/L), only low concentrations are expected in the pore water, which is the main exposure route for terrestrial plants.Since the pore water is the main route of uptake for terrestrial plants, the bioavailability of the substance is presumably low. An uptake of the substance by plant roots is also hindered by the high molecular weight of the substance (759 – 1095 g/mol) preventing the substance from crossing biological membranes. Therefore, tests with soil-dwelling organisms like earthworm which allows potential uptake via surface contact, soil particle ingestion and porewater (ECHA, 2012), are most relevant for the evaluation of terrestrial toxicity. In addition, in the absence of a clear indication of selective toxicity, an invertebrate (earthworm or collembolan) test is preferred, as outlined in ECHA guidance section R.7.11.5.3, page 122.

 

Moreover, carboxylic acids, C5-9, hexaesters with dipentaerythritol shows no inhibition to aquatic microorganisms in the read across with structurally similar analogue substances dipentaerythritol with fatty acids, C5 and C9iso (CAS 647028-25-9) and isononanoic acid, mixed esters with dipentaerythritol, heptanoic acid and pentaerythritol (CAS 84418-63-3). The applied test concentration is most likely in the range of concentrations that can be expected in the influent of a sewage treatment plant, as the substance has low water solubility (< 0.05 mg/L). The ECHA Guidance Document R.7c (ECHA, 2012) states that a test on soil microbial activity will only be additionally necessary for a valid PNEC derivation if inhibition of sewage sludge microbial activity has occurred. Therefore, toxicity to soil microorganisms is considered to be unlikely.

 

The available data are sufficient for an accurate hazard assessment of the terrestrial compartment. Based on all available data, further studies on the effects on terrestrial organisms do not have to be conducted since the chemical safety assessment indicates that toxicity to other terrestrial organisms in comparison to soil macroorganisms is not expected to be of concern.