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Toxicity to soil microorganisms

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Experimental data on the toxicity of 2,2-bis[[(1-oxoisononyl)oxy]methyl]-1,3-propanediyl diisononanoate (CAS 93803-89-5) to soil microorganisms are not available. In accordance with Regulation (EC) No. 1907/2006, Annex IX, column 2, 9.4 studies on terrestrial organisms do not need to be conducted when there is no risk indicated by the chemical safety assessment.

The test substance is characterized by a high log Koc (log Koc > 5) indicating a potential for adsorption to the soil particles. Tests with soil-dwelling organisms that feed on soil particles are therefore most relevant for the evaluation of soil toxicity 2,2-bis[[(1-oxoisononyl)oxy]methyl]-1,3-propanediyl diisononanoate. 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 for the target. This study show no effects on reproduction for earthworms in a chronic test according to OECD 222 (NOEC (56 d)≥1000 mg/kg soil dw). Moreover, 2,2-bis[[(1-oxoisononyl)oxy]methyl]-1,3-propanediyl diisononanoateshows no inhibition to aquatic microorganisms in the toxicity control of the biodegradation study resulting in a NOEC (14 d) of ≥ 29.1 mg/L. The applied test concentration is 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 DocumentR.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.

In conclusion, the substance is unlikely to pose a risk for terrestrial microorganisms based on a) low inhibition to aquatic microorganisms b) the low toxicity as expected for this substance for the terrestrial compartment based on the available experimental data and the lack of adverse effects in aquatic ecotoxicity tests.

In accordance with Regulation (EC) No. 1907/2006, Annex X, Column 2, 9.4 further studies on the effects on terrestrial organisms do not have to be conducted since the chemical safety assessment indicates that toxicity to soil microorganisms is not expected to be of concern.