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Adsorption / desorption

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Description of key information

A high log Koc for Fatty acids, C18-unsaturated, trimers (CAS No. 68937-90-6) is expected: log Koc > 5 

Key value for chemical safety assessment

Additional information

Because the substance is a composition of different homologues, the Koc values of well-defined representative structures were calculated with EPISUITE (KOCWIN v2.00) (Bucior 2012a, b, d, e, f, g, h) and a weight of evidence approach is applied.

The main factor determining the log Koc value of fatty acids is the carbon chain length. For monomers (C18), the calculated log Koc values are between 3.7 (octamethyldecanoic acid, MCI method) and 4.7 (octadecanoic acid, Kow method). It can be concluded that the overall contribution of monomers fulfills the condition: 4 < log Koc (monomers) < 5. The calculated results for dimeric constituents (C36) are considerably higher: log Koc from ca. 7.4 (Kow method) to ca. 9.1 (MCI method). The trimeric constituents (C54) are outside the applicability domain of QSAR models, and it can be assumed that log Koc is higher than the one for dimers. As the main fractions represented in the substance are the dimeric and trimeric fractions, it is concluded that for Fatty acids, C18- unsaturated, trimers (CAS 68937-90-6) adsorption to organic carbon in soils and sediments is to be expected. Log Koc is very high: log Koc > 5.

No additional tests on adsorption/desorption are to be conducted. The result is used for the chemical safety assessment.

References:

Bucior, K. (2012a) EPIsuite v 4.10 calculation with octadecanoic acid, dimer. Testing Laboratory: Knoell Consult, Mannheim, Germany. Owner Company: Members of Dimerised Fatty Acids Consortium. Report No. 20120301-buc-2.

Bucior, K. (2012b) EPIsuite v 4.10 calculation with octadecanoic acid. Testing Laboratory: Knoell Consult, Mannheim, Germany. Owner Company: Members of Dimerised Fatty Acids Consortium. Report No. 20120314-buc-7.

Bucior, K. (2012d) EPIsuite v 4.10 calculation with linoleic acid. Testing Laboratory: Knoell Consult, Mannheim, Germany. Owner Company: Members of Dimerised Fatty Acids Consortium. Report No. 20120314-buc-6.

Bucior, K. (2012e) EPIsuite v 4.10 calculation with oleic acid. Testing Laboratory: Knoell Consult, Mannheim, Germany. Owner Company: Members of Dimerised Fatty Acids Consortium. Report No. 20120314-buc-8.

Bucior, K. (2012f) EPIsuite v 4.10 calculation with linolenic acid. Testing Laboratory: Knoell Consult, Mannheim, Germany. Owner Company: Members of Dimerised Fatty Acids Consortium. Report No. 20120314-buc-9.

Bucior, K. (2012g) EPIsuite v 4.10 calculation with octamethyldecanoic acid. Testing Laboratory: Knoell Consult, Mannheim, Germany. Owner Company: Members of Dimerised Fatty Acids Consortium. Report No. 20120301-buc-3.

Bucior, K. (2012h) EPIsuite v 4.10 calculation with octadecanoic acid, trimer. Testing Laboratory: Knoell Consult, Mannheim, Germany. Owner Company: Members of Dimerised Fatty Acids Consortium. Report No. 20120302-buc-3.

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.