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Partition coefficient

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Description of key information

log Pow – experimental value: 4.65 (OECD 123, slow-stirring method)  
log Pow - calculated from weight-averaged log Koc value: 6.84 (calculation based on 2003 EU TGD)
log Pow - calculated using KOWWIN v1.68 (weight-averaged value): 7.30 (EPIsuite v4.10)

Key value for chemical safety assessment

Log Kow (Log Pow):

Additional information

The log Pow of the substance Octadecan-1-ol, ethoxylated, < 2.5 EO (CAS 9005-00-9) was determined experimentally using the slow-stirring method according to OECD Guideline 123. The value obtained is unexpectedly low. The analytical method to support the test involved ELSD. Since no reference substances for the pure alcohol or a purified C18 AE species were tested, is it not possible to deduce which, if any, of the possible constituents caused the ELSD response. Therefore the experimental log Pow value determined for this substance is questionable. Additionally, the result is not in line with experimental data for the free alcohol, as cited in the Hera report on Alcohol Ethoxylates (2009). Due to the uncertainty of the experimentalresult, it is not considered for the derivation of the key value for chemical safety assessment.

Therefore, the key value for chemical safety assessment, log Pow = 7.07 is derived in a weight-of-evidence approach from the various calculated log Pow values (average of 2 calculated values 6.84 and 7.30) for Octadecan-1-ol, ethoxylated, < 2.5 EO (CAS 9005-00-9).


The following types of calculations were applied:

1. based on weight-averaged log Koc values using the TGD equation for predominantly hydrophobic substances: log Koc = 0.81 log Pow + 0.10 thus log Pow = (log Koc – 0.10)/0.81 (2003 EU Technical Guidance Document on Risk Assessment Part III, Chapter 4, Section 4.3, pp 24 – 27)

2. based on EPIsuite v 4.10, KOWWIN v 1.68 log Pow values for (possible) individual constituents of the substance; a weighting based on normalized composition was applied to derive a log Pow value for the whole substance. Only the weight-averaged value was used as input value for derivation of the key value for chemical safety assessment.