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Toxicity to microorganisms

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Description of key information

No toxicological effects on microorganisms are expected up to 10000 mg/L nominal.

Key value for chemical safety assessment

Additional information

One study investigating the biodegradation of Fatty acids, C18-unsaturated, dimers, hydrogenated (CAS No. 68783-41-5) is available. The CO2 evolution test followed OECD guideline 301B using domestic activated sludge as inoculum. This test also contained a toxicity control. The toxicity control replicates each contained 1911 mL of mineral medium, 20 mL of microbial inoculum, the appropriate weight of test item and 69 mL of the reference material (sodium benzoate). This corresponds to 20 mg DOC/L for the test item and 20 mg DOC/L for sodium benzoate. Thus, the absolute amount of DOC in the toxicity control vessels with 2 L capacity amounts to 80 mg DOC/L. With 3.67 being the conversion factor (44/12) for carbon to carbon dioxide, the % degradation can be calculated with the following formula: % degradation = (mg CO2 produced) x 100/(mg TOC added x 3.67). Based on this, the toxicity control attained 55.7 % degradation after 28 days of incubation. Thus, in accordance with the OECD Guideline the test substance can be assumed to be non-inhibitory to microbial organisms.

Two further studies, investigating the toxicity of Fatty acids, C18-unsaturated, dimers (CAS No. 61788-89-4) to microorganisms were used as read across to support the available data for Fatty acids, C18-unsaturated, dimers, hydrogenated (CAS No. 68783-41-5), in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5., grouping of substance and read across approach.

The first study, a static GLP-cell multiplication inhibition test according or equivalent to ISO 10712, showed no effects on the growth of Pseudomonas putida at the tested WAF loading rates after 16 hours (EL10 / EL50 > 10000 mg/L, NOELR ≥ 10000 mg/L) (Sewell, 1997). The second test, is also a GLP cell multiplication inhibition study using Pseudomonas putida but following no guideline. After 18h no effects on the growth inhibition of Pseudomonas putida were observed (EC50 (18 h ) > 3500mg/L).

In summary, no toxicity to microorganisms is expected up to 10000 mg/L (nominal) for Fatty acids, C18-unsaturated, dimers, hydrogenated (CAS No. 68783-41-5).