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Classification & Labelling & PBT assessment

PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB

The PBT Assessment for Fatty acids, C18-unsaturated, dimers, “Dimer” (CAS No. 61788-89-4) is based on the criteria set out in the “Guidance on information requirements and chemical safety assessment, Chapter R.11: PBT Assessment” (ECHA, 2012).


Fatty acids, C18-unsaturated, dimers, “Dimer” showed not to be readily biodegradable in four OECD 301 ready biodegradation studies (< 10% after 28 d). Due to the very low biodegradation in these studies, the low solubility and high adsorption potential, it might be the case that the test substance is persistent especially in soil. Thus, as possible worst case, the persistence of the test substance in the environment is assumed.


The screening criterion for Bioaccumulation (B) stipulated in the ‘Guidance on information requirements and chemical safety assessment – Chapter R.11: PBT Assessment’ (ECHA, 2008) is a Log Kow > 4. Even though Log Kow values > 4 were estimated for the category members, no significant bioaccumulation in animal tissue is expected due their low potential to cross biological membranes and their metabolic fate in organisms. Thus, the category members can neither be considered to be bioaccumulative (B) nor very bioaccumulative (vB).



Long-term toxicity testing with Danio rerio resulted in no effects up to the water solubility limit for a read-across substance (ISO/DIS 10229-1). Moreover, the test substance is

not classified according to Directive 67/548/EEC and Regulation (EC) No. 1272/2008 (2nd ATP). Thus, the criteria set out in Annex XIII of Regulation (EC) No. 1907/2006 are not met and the test substance is not considered to meet the T criterion.



U.S. Environmental Protection Agency (2009). Risk-Based Prioritization Document. Initial Risk-Based Prioritization of High Production Volume (HPV) Chemicals – Fatty Acid Dimers and Trimer Category. pp 1-19. Report date: April 2009.


Lipinski et al. (2001) Experimental and computational approaches to estimate solubility and permeability in drug discovery and development settings, Adv. Drug Del. Rev., 2001, 46, 3-26.


Hsieh, A. and Perkins, E.G. (1976). Nutrition and Metabolic Studies of Methyl Ester of Dimer Fatty Acids in the Rat. Lipids, 11(10):763-768.


Paschke, R.F. et al. (1964). Dimer acid structures. The dehydro-dimer from methyl oleate and Di-t-butyl peroxide. Journal of the American Oil Chemists' Society 41(1):56-60.