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Toxicity to soil microorganisms

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Description of key information

The chemical safety assessment according to Annex I of Regulation (EC) No 1907/2006 does not indicate the need to investigate further toxicity testing with terrestrial organisms.

Key value for chemical safety assessment

Additional information

In accordance with Annex IX, column 2 of Regulation (EC) No 1907/2006, toxicity testing with terrestrial organisms does not need to be conducted as the Chemical Safety Assessment according to Annex I of Regulation (EC) No 1907/2006 does not indicate a need for further investigations.

No experimental data on toxicity to terrestrial microorganism are available for of N-methyl-N-(C18-(unsaturated)alkanoyl)glycine (EC 701-177-3). A chronic test according to OECD 222 (GLP) investigating the toxicity to earthworms with N-methyl-N-(C18-(unsaturated)alkanoyl)glycine (EC 701-177-3) is available resulting in a NOEC (56 d) of 171 mg/kg dw for Eisenia andrei. Tests with soil-dwelling organisms that feed on soil particles are most relevant for the evaluation of soil toxicity as they allow potential uptake via surface contact, soil particle ingestion and porewater (ECHA, 2017).

According to Chapter R7.b of the Guidance on information requirements and chemical safety assessment (ECHA, 2017), a test on soil microbial activity will be additionally necessary only if inhibition of sewage sludge microbial activity has occurred. In a toxicity control of a biodegradation study for the target substance no inhibition of sewage sludge microbial activity has been observed (86.7% after 14 d). In addition, respiration inhibition tests with activated sludge (OECD 209) for the target substance show acute effects above 10 mg/L, which is in adition above the water solubility range (0.44 mg/L). Thus, the degradation process in commercial sewage treatment plants is not suspected to be inhibited by the target substance and no test on soil microbial activity is additionally necessary. This absence of acute toxicity (effect values avove 10 mg/L) can be used to waive the data requirements of Annex X (Chapter R.7c: Endpoint specific guidance, 2017, page 148).

The PNEC soil was derived with the NOEC from the long-term toxicity test with soil macroorganisms (Eisenia Andrei, OECD 222), as this is the most realistic value for evaluation of terrestrial toxicity. Thus, the PNEC soil based on experimental data was used for evaluation of the PEC/PNEC ratio. This screening assessment indicates no risk for the terrestrial compartment (RCR < 1; please refer to Chapter 9 and 10 of the Chemical Safety Report for detailed information). Thus, according to Guidance on information requirements and chemical safety assessment, R.7c (ECHA, 2017), no toxicity testing for terrestrial microorganisms needs to be done. In addition, invertebrates are the most sensitive organism in the aquatic compartment. No higher toxicity of the test substance is expected for terrestrial plants in comparison to soil macroorganisms.

Moreover, due to calculated Log Koc values (Log Koc of 1.93 – 3.37 (pH 4 – pH 9, Franco, Fu and Trapp)), a low to moderate potential for adsorption to particles is expected in soil. Even if exposed to the soil the substance is readily biodegradable indicating that it will not be persistent in the environment. Considering this, one can assume that the availability of N-methyl-N-(C18-(unsaturated)alkanoyl)glycine (EC 701-177-3) in the soil environment is very low, which reduces the probability of exposure, in particular long-term exposure, of soil organisms in general.

Thus, the available data investigating the toxicity to terrestrial macroorganisms are sufficient to assess the hazard of N-methyl-N-(C18-(unsaturated)alkanoyl)glycine (EC 701-177-3) to terrestrial organisms and no further test on terrestrial microorganisms is considered to be necessary.