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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB

The PBT Assessment for Fatty acids, C16-18, isobutyl esters (CAS No. 85865-69-6) is based on the criteria set out in the “Guidance on information requirements and chemical safety assessment, Chapter R.11: PBT Assessment” (ECHA, 2008).


The read-across substance Fatty acids, C16-18, butyl esters (CAS No. 85408-76-0) is readily biodegradable in one study according to ISO 10708/BODIS (82% (O2 consumption) after 28 d). Thus, Fatty acids, C16-18, isobutyl esters does not meet the screening criterion for persistence and it is not considered to be P or vP.


Due to the low water solubility, rapid environmental biodegradation and metabolisation via enzymatic hydrolysis of the SCAE C2-C8 category members, a relevant uptake and bioaccumulation in aquatic organisms is not expected. Enzymatic breakdown will initially lead to the free fatty acid and the free alcohol. From literature it is well known, that these hydrolysis products will be metabolised and excreted in fish effectively (Heymann, 1980; Lech & Bend, 1980; Lech & Melancon, 1980; Murphy & Lutenske, 1990). This is supported by the low calculated BCF value of 3.51 - 14.07 L/kg ww (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic). Please refer to IUCLID Section 5.3 for a detailed overview on bioaccumulation of the SCAE C2-C8 Category members.


Long-term toxicity testing with Daphnia magna resulted in a NOELR of ≥ 100 mg/L for the read-across substance Fatty acids, C16-18 and C18 unsaturated isobutyl esters (CAS No. 84988-79-4) (OECD 202 part 2). Moreover, Fatty acids, C16-18, isobutyl esters is not classified according to Directive 67/548/EEC and Regulation (EC) No. 1272/2008. Thus, the criteria set out in Annex XIII of Regulation (EC) No. 1907/2006 are not met and Fatty acids, C16-18, isobutyl esters is not considered to meet the T criterion.