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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

EL10 (6 h) > 50 mg/L (ISO 10712, Pseudomonas putida), read across
NOEC (14 d) > 28.7 mg/L (OECD 301 B, Toxicity Control), read across

Key value for chemical safety assessment

Additional information

Since no experimental studies investigating the toxicity of 3,5,5 trimethylhexanoic acid, mixed esters with dipentaerythritol (CAS 84418-63-3, UVCB) towards aquatic microorganisms are available, in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 a read across to the structurally related source substance 3,5,5-trimethylhexanoic acid hexaester with dipentaerythritol (CAS 84418-63-3, mono) was conducted. This read-across is justified in detail in the overall summary (IUCLID section 6.1) and within the analogue justification in IUCLID section 13. Both substances consist of the same alcohol component (dipentaerythritol) and an equal fatty acid chain length (C9iso, respectively) but with different degrees of esterifications.

One study investigating the toxicity of 3,5,5-trimethylhexanoic acid hexaester with dipentaerythritol (CAS 84418-63-3) to aquatic microorganisms is available. The GLP study was conducted similarly to ISO 10712 investigating the inhibition of growth of Pseudomonas putida (Comber, 1993). A Water Accommodated Fraction (WAF) of nominal 50 mg/L was used for the test. No inhibitory effect was observed after 6 h. Hence the EL10 was determined to be > 50 mg/L (nominal) based on growth inhibition.

Additionally a ready biodegradability study for this substance was used to derive a NOEC for the toxicity to aquatic microorganisms. In accordance with the ECHA Guidance R.7b (ECHA, 2014) the result from a biodegradation study can be used to derive a NOEC if a compound degrades well in a ready biodegradability test, or does not inhibit the degradation of a positive control at a certain concentration (biodegradation > 25%). The toxicity control in this OECD 301B test, containing 28.7 mg/L of the test item and 26 mg/L of the reference material aniline attained 41.5% degradation after 14 days of incubation. Thus, a NOEC of ≥ 28.7 mg/L was derived for 3,5,5-trimethylhexanoic acid hexaester with dipentaerythritol (CAS 84418-63-3).

Based on the available results from this structurally related read-across substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which is characterized by a similar ecotoxicological profile and comparable structure, it can be concluded that 3,5,5 trimethylhexanoic acid, mixed esters with dipentaerythritol (CAS 84418-63-3) will not exhibit adverse effects to aquatic microorganisms even at concentrations well above the limit of water solubility.