Alcohols, C16-18 and C18-unsatd., ethoxylated

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

mixture rules calculation

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Calculation from experimentally derived Koc data using an equation form the 2003 EU Technical Guidance Document on Risk Assessment Part III, Chapter 4, Section 4.3

Qualifier:

according to guideline

Guideline:

other: 2003 EU Technical Guidance Document on Risk Assessment Part III, Chapter 4, Section 4.3, p. 26

Principles of method if other than guideline:

Log Kow was calculated using an equation derived from experimentally determined Koc values for analogue structures using the 2003 TGD equation for predominantly hydrophobic substances.

GLP compliance:

no

Type of method:

other: calculation from log Koc values

Partition coefficient type:

octanol-water

Type:

log Pow

Partition coefficient:

6.61

Remarks on result:

other: weight-averaged value

Details on results:

Weight-averaged log Koc of the whole substance based on normalized composition: 5.46.
This value was used in the rearranged TDG equation mentioned above resulting in a log Pow value of 6.61.

Reference 2

Endpoint:

partition coefficient

Type of information:

mixture rules calculation

Adequacy of study:

weight of evidence

Study period:

2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

QSAR prediction: migrated from IUCLID 5.6

Principles of method if other than guideline:

The calculations were performed for the linear free alcohols and ethoxylated alcohols (AE) with ethoxylation degree of 1 and 3, respectively, using EPISuite v4.10, KOWWIN v1.68.
In order to derive a single value for risk assessment, the various calculated Log Pow values were weight-averaged using normalized values for composition (free alcohols, C16 AE and C18 AE).

GLP compliance:

no

Type of method:

other: QSAR

Partition coefficient type:

octanol-water

Type:

log Pow

Partition coefficient:

7.01

Remarks on result:

other: weight-averaged value

QSAR result; pH and temperature are not reported. For detailed description of the model and its applicability, see "Any other information on materials and methods incl. tables".

Individual calculated values for log Pow for each ‘sub’-group

Structure	SMILES notation used in calculation	EPI log Pow calc.
Alcohol, C16	CCCCCCCCCCCCCCCCO	6.73
Alcohol, C18	CCCCCCCCCCCCCCCCCCO	7.72
Alcohol ethoxylate, C16, 1 EO	OCCOCCCCCCCCCCCCCCCC	6.46
Alcohol ethoxylate, C18, 1 EO	OCCOCCCCCCCCCCCCCCCCCC	7.44
Alcohol ethoxylate, C16, 3 EO	OCCOCCOCCOCCCCCCCCCCCCCCCC	5.91
Alcohol ethoxylate, C18, 3 EO	OCCOCCOCCOCCCCCCCCCCCCCCCCCC	6.89

 

Mean calculated values for log Pow for each ‘sub’-group

	Mean log Pow calc.
Free alcohols (avg of C16, C18)	7.23
C16-EO (avg of 1EO and 3EO)	6.19
C18-EO (avg of 1EO and 3EO)	7.17

 

Result:

Weight-averaged log Pow of the whole substance based on normalized composition: 7.01

Reference 3

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

27 Sep - 4 Oct 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)

GLP compliance:

yes

Type of method:

slow-stirring method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

> 6.75

Temp.:

25 °C

pH:

>= 5.2 - <= 5.3

The concentration of the test item in the aqueous and 1 -octanol phase was determined after 68, 70, 72 and 74 hours, ensuring that an equilibrium concentration was established in both phases. At each test time, three different test solutions were analysed. The results are given in the table:

Time (h)	Octanol phases, test mixture (mg/g)			Aqueous buffer phases, test mixture (µg/g)
	1	2	3	1	2	3
68	27.6	26.4	28.9	< 0.005	< 0.005	< 0.005
70	26.4	27.6	28.7	< 0.005	< 0.005	< 0.005
72	27.4	28.7	28.3	< 0.005	< 0.005	< 0.005
74	25.8	28.0	27.8	< 0.005	< 0.005	< 0.005

The concentration of the test item in the aqueous phases was below the detection limit of the analytical method.

For each time interval the Pow and log Pow values are calculated for each test mixture. The results are summarized in the table:

Time (h)	Calculated Pow values, test mixture no.			Calculated log Pow values, test mixture no.
	1	2	3	1	2	3
68	>5.52E+06	>5.28E+06	>5.78E+06	>6.742	>6.723	>6.762
70	>5.28E+06	>5.52E+06	>5.74E+06	>6.723	>6.742	>6.759
72	>5.48E+06	>5.74E+06	>5.66E+06	>6.739	>6.759	>6.753
74	>5.16E+06	>5.60E+06	>5.56E+06	>6.713	>6.748	>6.745

pH values of aqueous phases varied between 5.2 and 5.3.

Description of key information

log Pow - experimental value (slow-stirring method - OECD 123): > 6.75 at 25 °C

log Pow - calculated from weight-averaged log Koc value: 6.61
log Pow - calculated using KOWWIN v1.68 (weight-averaged value): 7.01
log Pow - calculation based on the solubility in n-octanol and water: >=3.8

Key value for chemical safety assessment

Log Kow (Log Pow):

6.81

at the temperature of:

25 °C

Additional information

The log Pow of the substance was determined in a weight of evidence approach from various calculated and experimental log Pow values. The log Pow >6.75 was determined experimentally using the slow stirring method according to OECD Guideline 123. Additionally the following 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.

3. based on solubility of the substance in n-octanol and water. The obtained value (log Pow >= 3.8) provides only the lower limit and thus it is not considered in a calculation of the key value for chemical safety assessment, however it confirms the hydrophobic character of the substance.

The key value for the chemical safety assessment is derived in a weight-of-evidence approach from the two calculated log Pow values (average of values: 6.61 and 7.01). Since the experimental (slow-stirring) result is given as log Kow >6.75, a very good coincidence is achieved.