Fatty acids, C16-18 (even numbered) and C18-unsatd., branched and linear, di- and triesters with trimethylolpropane

Biodegradation in water: screening tests

Description of key information

Readily biodegradable: 86% (O2 consumption) after 28 d (OECD 301F)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Since no valid studies investigating the ready biodegradability of Fatty acids, C16-18 (even numbered) and C18-unsatd., branched and linear, di- and triesters with trimethylolpropane (former CAS 85005-23-8) are available for this endpoint, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read across to the structurally related category members Fatty acids, C16-18 (even numbered) and C16-18-unsatd. (even numbered), triesters with trimethylolpropane (CAS 68002-79-9), Fatty acids, C16-18 and C18 unsatd., triesters with trimethylolpropane (CAS 68002-78-8) and 2-ethyl-2-(((1-oxoisooctadecyl)oxy)methyl)-1,3-propanediyl bis (isooctadecanoate) (CAS 68541-50-4) was conducted. The read-across substances are representative to evaluate the biodegradation of Fatty acids, C16-18 (even numbered) and C18-unsatd., branched and linear, di and triesters with trimethylolpropane since they have a similar structure (C18 unsatd. and branched (source) compared to C16-18 and C18 unsatd. linear and branched) and thus cover the target substance adequately.

The first study with the read-across substance Fatty acids, C16-18 (even numbered) and C16-18-unsatd. (even numbered), triesters with trimethylolpropane (CAS 68002-79-9) was performed according to OECD 301F (Manometric Respirometry) with sewage effluent as inoculum (Börner, 2000). After 28 d a biodegradation of 86% (O2 consumption) was observed and the 10-day window was fulfilled. Thus, the substance is readily biodegradable according to the OECD criteria.

The second study with the read-across substance Fatty acids, C16-18 and C18 unsatd., triesters with trimethylolpropane (CAS 68002-78-8) was performed according to OECD 301B with domestic activated sludge as inoculum (Bouillon, 2012). Based on the CO2 production of the inoculum a degradation rate of 86.6% was determined at test termination indicating that the substance is readily biodegradable according to the OECD criteria.

The third study with the read-across substance 2-ethyl-2-(((1-oxoisooctadecyl)oxy)methyl)-1,3-propanediyl bis (isooctadecanoate) (CAS 68541-50-4) was performed according to OECD 301B as well (Oggier, 2011). Domestic activated sludge was used as inoculum. The degradation rate was determined by measuring the CO2 evolution of the inoculum. After 28 days of incubation a degradation rate of 91% was determined. Thus, the substance is regarded as readily biodegradable according to OECD criteria.

The results of two studies for Fatty acids, C16-18 (even numbered) and C18-unsatd., branched and linear, di- and triesters with trimethylolpropane (former CAS 85005-23-8) must be evaluated with caution (34% - 65% degradation within 29 days), because optimum test conditions were not met (percentage degradation of the reference substance did not reach the pass level by day 14, unspecified reference substance is no suitable compound). Nonetheless, in one of these studies (Hales and Hammond, 1993) 65% at 10 mg/L test concentration degraded within 29 days, supporting the result of the analogue substance.

Based on the results from structurally related read-across substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) it can be concluded that Fatty acids, C16-18 (even numbered) and C18-unsatd., branched and linear, di- and triesters with trimethylolpropane (former CAS 85005-23-8) is readily biodegradable according to the OECD criteria.