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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Readily biodegradable: 71.1 - 84.5% after 28 d (OECD 301B)

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Since no studies investigating the ready biodegradability of Fatty acids, rape-oil, mixed esters with 1,4:3,6-dianhydro-d-glucitol, sorbitan and sorbitol (CAS 93334-10-2) are available for this endpoint, in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 a read across to the structurally related analogue substance sorbitane oleate (CAS 1338-43-8) was conducted.
This read across is justified as both substances have a comparable structure. The source substance sorbitan oleate is characterized by sorbitol esterified with a C18 unsaturated fatty acid.

Based on the specification the target substance Fatty acids, rape-oil, mixed esters with 1,4:3,6-dianhydro-d-glucitol, sorbitan and sorbitol is characterized by the alcohol components sorbitol, sorbitan and 1,4:3,6-dianhydro-d-glucitol esterified as mono (mainly), -di- or tri-ester with mainly fatty acids of C18 and C18 unsaturated. The difference in alcohol components is not suspected to result in any difference in biodegradation (all C6 alcohols) between target and source substance. Further justification is given within the endpoint summary 6.1 and within the analogue justification in section 13.

The key study with the read-across substance sorbitane oleate (CAS 1338-43-8) was performed according to OECD 301B (non-GLP) under aerobic conditions using non-adapted activated sludge as inoculum with a test substance concentration of 10 - 20 mg/L (van Dievoet, 2005). A biodegradation of 71.1 - 84.5% (CO2 evolution) was observed after 28 d. Since the substance reached the pass level for OECD 301B (biodegradation is > 60% after 28 d, passing the 10-day window) sorbitane oleate is readily biodegradable according to the OECD criteria.

The supporting study was performed according to an ISO draft for the BOD Test for Insoluble Substances (BODIS test) under GLP conditions (Richterich, 1992). A biodegradation of 95% (O2 consumption) was recorded after 28 d passing the 10-day window. Thus, this result confirms the result from the key study and sorbitane oleate can be considered as readily biodegradable according to the OECD criteria.

Based on the results from one structurally related read-across substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) it can be concluded that Fatty acids, rape-oil, mixed esters with 1,4:3,6-dianhydro-d-glucitol, sorbitan and sorbitol is readily biodegradable according to the OECD criteria.