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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
key study
Study period:
November 2013
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Validated QSAR calculation method, using EPIWIN suite, KOWWIN version 1.68 model. A QPRF is attached. The substance is recognised as part of the rulebase utilised by the EPI Suite model data set, and is in model Applicability Domain. Further details can be found within the appended report below or at http://www.epa.gov/oppt/exposure/pubs/episuite.htm. This system is recognised in ECHA Guidance document CHAPTER R.6 – QSARS AND GROUPING OF CHEMICALS, Pg 47
Qualifier:
no guideline followed
Principles of method if other than guideline:
The substance is a hydrocarbon UVCB. Standard tests for water solubility are intended for single substances and are not appropriate for this complex substance. It is unlikely that a study result would give anything other than a “greater than” limit value of the highest value available in the test. This endpoint is therefore characterized using quantitative structure property relationships for representative hydrocarbon structures that could be present within this UVCB substance. 70 proposed molecules are assessed, in order to provide a suitable range of likely values associated with the substance. Details on the KOWWIN version 1.68 model programme are detailed below under "methods".
GLP compliance:
no
Type of method:
other: Calculated range of values using EPIWIN KOWWIN version 1.68 model
Partition coefficient type:
other: Calculated range of values using EPIWIN KOWWIN version 1.68 model
Analytical method:
other: QSAR estimate using US EPA On-Line EPI Suite™ KOWWIN version 1.68 model
Type:
log Pow
Partition coefficient:
>= 7.49 - <= 31.33
Temp.:
25 °C
pH:
7
Remarks on result:
other: Calculated range of values using EPIWIN KOWWIN version 1.68 model
Details on results:
Results estimated using the US EPA On-Line EPI Suite™ KOWWIN version 1.68 model the log Kow range is predicted to be 7.49 to 31.33. Tabulated data of all isomers assessed and associated results is provided below for information.

Tabulated data from evaluation of various potential structures present in NovaSpec 450 Base Oil

Derivation

SMILES Code

Molecular Formula

MW

Log Kow calculated usingKOWWIN version 1.68

1

M

CC(C)CCCC(C)CCCC(C)CC

C15H32

212.41

7.49

2

M-C8

CC(C)C(CCC(C)CCCC(C)CC)C(CC)CCCCC

C23H48

324.63

11.27

3

M-C10

CC(C)C(CCC(C)CCCC(C)CC)C(CCCC)CCCCC

C25H52

338.65

12.25

4

M-C12

CC(C)C(CCC(C)CCCC(C)CC)C(CCCCC)CCCCCC

C27H56

380.73

13.23

5

M-C14

CC(C)C(CCC(C)CCCC(C)CC)C(CCCCCCCC)CCCCC

C29H60

408.79

14.22

6

M-C16

CC(C)C(CCC(C)CCCC(C)CC)C(CCCCCCCCCC)CCCCC

C31H64

436.84

15.2

7

M-C8

CCC(CCCCC)C(CCC(C)C)C(C)CCCC(C)CC

C23H48

324.63

11.27

8

M-C8

CCC(CCCCC)C(CCC(C)CC)C(C)CCCC(C)C

C23H48

324.63

11.27

9

M-C10

CC(CCCC(C)CCCC(C)CC)CC(CCCCC)CCCC

C25H52

338.65

12.32

10

M-C10

CC(CCCC(C)CC)C(CCC(C)C)C(CCCCC)CCCCCC

C25H52

338.65

13.23

11

M-C12

CC(CCCC(C)CC)C(CCC(C)C)C(CCCCC)CCCCCC

C27H56

380.73

13.23

12

M-C12

CC(CCCC(C)C)C(CCC(C)CC)C(CCCCCC)CCCCC

C27H56

380.73

13.23

13

M-C12

CC(CC)C(CCC(C)CCCC(C)C)C(CCCCC)CCCCCC

C27H56

380.73

13.23

14

M-C12

CC(CCCC(C)C)C(CCC(C)CC)C(CCCC)CCCCCCC

C27H56

380.73

13.23

15

M-C14

CC(CC(CCCCCC)CCCCCCC)CCCC(C)CCCC(C)CC

C29H60

408.79

14.29

16

M-C14

CC(CCCC(C)CC)C(CCC(C)C)C(CCCCC)CCCCCCCC

C29H60

408.79

14.22

17

M-C14

CC(CC)C(CCC(C)CCCC(C)C)C(CCCCC)CCCCCCCC

C29H60

408.79

14.22

18

M-C14

CC(CCCC(C)CC)C(CCC(C)C)C(CCCCCCCCC)CCCC

C29H60

408.79

14.22

19

M-C14

CC(CCCC(C)C)C(CCC(C)CC)C(CCCCCCC)CCCCCC

C29H60

408.79

14.22

20

M-C16

CC(CCCC(C)CCCC(C)CC)CC(CCCCCCCC)CCCCCCC

C31H64

436.84

15.27

21

M-C16

CC(C)CCC(C(CCCCCCCC)CCCCCCC)C(C)CCCC(C)CC

C31H64

436.84

15.2

22

M-C16

CC(C)C(CCCCCCCCCCCCCCCC)CCC(C)CCCC(C)CC

C31H64

436.84

15.27

23

M-Farn

CC(CC(CCC(C)CCCC(C)CC)C(C)C)CCCC(C)CCCC(C)CC

C30H62

422.81

14.56

24

M-Farn

CC(C)CCCC(CCCC(C)CC)CC(CCC(C)CC)C(C)CCCC(C)C

C30H62

422.81

14.56

25

M-Farn-C8

CC(C)CCCC(C)CCC(CC(CCCC(C)CC)CCC(C(CC)CCCCC)C(C)C)C(C)CC

C38H78

535.03

18.34

26

M-Farn-C8

CC(CCCC(C)CCCC(C)CCCC(C)CCCC(C)CC)C(CCC(C)C)CCCCCCCC

C38H78

535.03

18.49

27

M-Farn-C10

CC(C)CCCC(C)CCC(CC(CCCC(C)C(CCC(C)C)C(CCCCCCC)CC)CC)C(C)CC

C40H82

563.08

19.32

28

M-Farn-C12

CC(CCCC(C)C)C(CCC(CC(CCC(C)CCCC(C)C)C(C)CC)CC)C(CCCCC)CCCCCC

C42H86

591.13

20.31

29

M-Farn-C14

CC(C)C(CCC(C)CCCC(C)CC)C(CC(C)CCCC(C)CC)C(C(C)C)C(CCCC)CCCCCCCCC

C44H90

619.18

21.21

30

M-Farn-C16

CC(CC(CCCC)CCCCCCCCCCC)CCCC(CCCC(C)CC)CC(CCC(C)C)C(C)CCCC(C)CC

C46H94

647.24

22.34

31

M-C8-C12

CCCCCC(CC(CC)CCCC(C)C(CCC(C)C)C(CCCCC)CC)CCCCCC

C35H72

492.95

17.09

32

M-C8-C14

CCCC(CCCCCCCCCC)CC(CCC(CCCCCCCC)C(C)C)CCCC(C)CC

C37H76

520.99

18.14

33

M-C8-C16

CC(CCCC(C)CC)CCCC(CCCCCCCCC)CC(CCCC)CCCCCCCCCCC

C39H80

549.05

19.2

34

M-C10-C8

CCCCC(CCCCC)C(CCC(CC(C)CCCCCC)CCCC(C)CC)C(C)C

C33H68

464.89

16.11

35

M-C10-C12

CCC(CCCCCCC)C(CCC(C)CC)C(C)CCCC(C)CC(CCCCCC)CCCCC

C37H76

520.99

18.07

36

M-C10-C16

CCC(CCCCCCC)C(CCC(C)CC)C(C)CCCC(C)CC(CCCCC)CCCCCCCCCC

C41H84

577.11

20.04

37

M-C12-C8

CC(CCCCCC)CC(CC)CCCC(C)C(CCC(C)C)C(CCCCC)CCCCCC

C35H72

492.95

17.09

38

M-C12-C14

CC(CC(CCCCCCCC)CCCCC)CCC(C(CCCCC)CCCCCC)C(C)CCCC(C)CC

C41H84

577.11

20.04

39

M-C12-C16

CCCCCC(CC(CCCC(C)CC)CCCC(C)CCCCCCCCCCCCC)CCCCCCCCCC

C43H88

605.16

21.16

40

M-C14-C8

CC(C)C(CCC(CCCC(C)CC)CC(C)CCCCCC)C(CCCCC)CCCCCCCC

C37H76

520.99

18.07

41

M-C14-C10

CCCCC(CCCCCCCCC)C(CCC(C)CC)C(CC(C)CCCCCCCC)CCCC(C)C

C39H80

549.05

19.05

42

M-C14-C16

CCCCCCCCCCCC(CCCC)CC(CCCC(C)CC)CCCC(C)CC(CCCCCCCC)CCCCC

C45H92

633.21

22.07

43

M-C16-C8

CC(C)C(CCC(CC(C)CCCCCC)CCCC(C)CC)C(CCCCCCCCCC)CCCCC

C39H80

549.05

19.05

44

M-C16-C16

CC(CC(CCCCCCCCCC)CCCCC)C(CCC(C)CCCC(C)CC)CCCCCCCCCCCCCCCC

C47H96

661.26

23.06

45

M-Farn-Farn (Deriv 1)

CC(C)CCCC(C)CCCC(CC)CC(CCC(C)CC)C(C)CCCC(C)CC(CCC(C)CC)C(C)CCCC(C)C

C45H92

633.21

21.63

46

M-Farn-Farn (Deriv 2)

CC(CCCC(C)CCCC(C)CCCC(C)CC)C(CC(C)CCCC(C)CCCC(C)CC)CCC(C)CCCC(C)C

C45H92

633.21

21.71

47

M-Farn-Farn (Deriv 3)

CC(CC(CCC(C)CCCC(C)CC)C(C)CC(CCC(C)CCCC(C)CC)C(C)C)CCCC(C)CCCC(C)CC

C45H92

633.21

21.63

48

M-C8-C8-C8

CC(C)C(CCC(CC(C)CCCCCC)CCC(CCCCCCCC)C(C)CC)C(CC)CCCCC

C39H80

549.05

18.98

49

M-C10-C10-C10

CC(CC(CC(C)CC)CCCCCCCCCC)C(CCCCCCCCCC)CCC(C)CCCCCCCCCCC

C45H92

633.21

22.07

50

M-C12-C12-C12

CC(C(C)CCCC(CCCC(C)CC(C)CCCCCCCCCC)CC(C)CCCCCCCCCC)C(CCCCCC)CCCCC

C51H104

717.37

24.87

51

M-C14-C14-C14

CCCCCC(CC(CCCC(C)C(CCC(C)CCCCCCCCCCCCCCC)C(CCCCCCCC)CCCCC)CC)CCCCCCCC

C57H116

801.53

27.89

52

M-C16-C16-C16

CCCCCCCCCC(CC(CCCC(C)C(CCCCCCCCCCCCCCCC)CCC(C)CC(CCCCCCC)CCCCCCCC)CC)CCCCCC

C63H128

885.69

31.33

53

M-Farn-Farn-C8

CC(CCCC(CC(CCCCC)CC)C(CCC(C)C)C(CCC(C)C)C(C)CCCC(C)CC)CCCC(CCCC(C)C)CCCC(C)CC

C53H108

745.42

25.49

54

M-Farn-Farn-C10

CC(CCCC(C)CC(CC(CC(C)CCCC(C)CCCC(C)CC)C(C)C(C)CCCCCCCCCC)C(C)CCCC(C)C)CCCC(C)CC

C55H112

773.48

26.96

55

M-Farn-Farn-C12

CC(CCCC(C)C)C(CCC(C)CC)CC(CCCC(C)CCC(CC(C)CCCC(C)CCCC(C)CC)C(C)CC)CC(CCCCCC)CCCCC

C57H116

801.53

27.45

56

M-Farn-Farn-C14

CC(CC(CCC(C)CCC(CCCC(C)C)CCCC(C)CC)C(C)CCCC(C)CC)C(CCC(C)CCCC(C)CC)C(CCCCCCC)CCCCCC

C59H120

829.58

28.43

57

M-Farn-Farn-C16

CC(C)CCCC(CCCC(C)CC)CCC(CCCC(C)CCC(CCCCCCCCC)CCCCCC)C(CC(CCCC(C)CC)CCCC(C)C)CCC(C)C

C61H124

857.64

29.49

58

M-Farn-C8-C10

CC(CCCC(C)CC)CCCC(C)CCC(CCCC(C)CCCC(C)C(C)CCCCCCCCCC)CCCCCCCCC

C48H98

647.24

23.4

59

M-Farn-C10-C14

CC(CCCC(C)CC)CCCC(CCC(CCCC(C)CCCC(C)CCCCCCCCCCC)CC)CC(CCCC)CCCCCCCCC

C54H110

759.45

26.35

60

M-Farn-C14-C16

CCCCCCCCC(CCCCC)C(CCC(C)C)C(C)CCCC(CCC(CC)C(CCC(C)CCCC(C)C)C(CCCCCCC)CCCCCCCC)CC

C60H112

843.61

29.07

61

M-Farn-C16-C16

CC(CCCC(C)CC)C(CCC(C)CCC(CC(CC)CCCCCCCCCCCCC)CCCC(C)CCCC(C)CC)CCCCCCCCCCCCCCCC

C62H126

871.66

30.2

62

M-Farn-C8-C16

CCCC(CCCC)C(CCC(C)CC)C(CCC(CCCC(C)CC)CCCC(C)CC(CCCCCCCCCC)CCCCC)CCCC(C)C

C54H110

759.45

26.2

63

M-C8-C10-C12

CC(CCCC(C)CCCC(CC(CCCCC)CC)C(C)C(CC)CCCCCCC)CCCCCCCCCCCCC

C45H92

633.21

22

64

M-C12-C14-C16

CCCCC(CC(CCCC(C)C(C)C(CCCCCC)CCCCCCCCC)CCCC(C)CCCCCCCCCCCCC)CCCCCCCCC

C57H116

801.53

27.89

65

M-C8-C12-C16

CC(C(CC(C)CCCCCCCCCC)CCCC(C)CCCC(C)CC(CCCCCCCC)CCCCCCC)C(CCCCC)CC

C51H104

717.37

24.87

66

M-C10-C12-C14

CCCCC(CCCCCCC)C(CCC(C)CCC(CCCCC)CCCC)C(C)CCCC(C)CC(CCCCCC)CCCCCCC

C51H104

717.37

24.87

67

M-C8-C14-C16

CC(CCC(CCCCCCCC)C(C)CCCC(C)CCC(C)CCCCCCCCCCCC)CC(CCCCCCCCC)CCCCCC

C53H108

745.42

25.93

68

M-Farn-Farn-Farn (Deriv 1)

CC(CC(CCC(C)CC)C(CC(CCC(C)CCCC(C)CC)C(C)C)CCCC(C)CCC(CCCC(C)CCCC(C)C)CC)CCCC(C)CCCC(C)CC

C60H112

843.61

28.78

69

M-Farn-Farn-Farn (Deriv 2)

CC(C)C(CCC(C)CCCC(C)CC)CC(C)C(CCC(C)C(CC(C)CCCC(C)CCCC(C)CC)CCC(C)CC)C(CCC(C)CCCC(C)CC)C(C)C

C60H112

843.61

28.63

70

M-Farn-Farn-Farn (Deriv 3)

CC(CC)CCCC(C)CCCC(C)CCC(CCCC(C)CC(C)C(C)CCCC(C)C(CCC(C)C)C(CCC(C)C)C(C)CCCC(C)CC)CCCC(C)CC

C60H112

843.61

28.7

 

Conclusions:
Using the US EPA On-Line EPI Suite™ KOWWIN version 1.68 model, the log Kow range is predicted to be 7.49 to 31.33. This indicates that the substance in theory could have the potential to bioaccumulate. The substance is, however, considered to be not bioavailable to aqueous organisms as demonstrated by both the lack of acute toxicity and any associated adverse effects in the acute toxicity studies on aquatic organisms. Furthermore, the high log Pow is considered to be more a consequence of poor water solubility than a lipophilic tendency and is considered to be not indicative of the tendency to bioaccumulate in lipid tissues of aquatic organisms. This is based in part on an evaluation of literature data which demonstrates a tendency for the Bioconcentration Factor (BCF) to decrease as Log Pow increases above 6. This assumption is further confirmed by the data set available on “white oils” which demonstrates that they are poorly absorbed, and are not bioaccumulative in mammals. REGULATION (EC) No 1272/2008 as amended by COMMISSION REGULATION (EU) No 286/2011 of 10 March 2011 states as follows when deciding the criteria for bioaccumulation potential:Cases when data do not allow classification under the above criteria but there are nevertheless some grounds for concern. This includes, for example, poorly soluble substances for which no acute toxicity is recorded at levels up to the water solubility (note 3), and which are not rapidly degradable and have anexperimentally determined BCF ≥ 500 (or, if absent, a log Kow ≥ 4), indicating a potential to bioaccumulate, will be classified in this category unless other scientific evidence exists showing classification to be unnecessary. Such evidence includes chronic toxicity NOECs > water solubility or > 1 mg/l, or evidence of rapid degradation in the environment.It is considered that sufficient evidence exists for avoidance of classification for bioaccumulative effects. White oils are not absorbed within the body, nor do they demonstrate any toxicity to mammalian or environmental organisms. As such, the “high” calculated Log Kow value associated with these types of substances is not proposed to be indicative of the propensity of the substance to become bioaccumulated. No classification is proposed on this basis.
Executive summary:

The substance is a hydrocarbon UVCB. Standard tests for partition coefficient are intended for single substances and are not appropriate for this complex substance. It is unlikely that a study result would give anything other than a “greater than” limit value of the highest value available in the test. This endpoint is therefore characterized using quantitative structure property relationships for representative hydrocarbon structures that could be present within this UVCB substance. 70 proposed molecules are assessed, in order to provide a suitable range of likely values associated with the substance.

Using the US EPA On-Line EPI Suite™ KOWWIN version 1.68 model, the log Kow range is predicted to be7.49 to 31.33. This indicates that the substance in theory could have the potential to bioaccumulate.  The substance is, however, considered to be not bioavailable to aqueous organisms as demonstrated by both the lack of acute toxicity and any associated adverse effects in the acute toxicity studies on aquatic organisms. Furthermore, the high log Pow is considered to be more a consequence of poor water solubility than a lipophilic tendency and is considered to be not indicative of the tendency to bioaccumulate in lipid tissues of aquatic organisms. This is based in part on an evaluation of literature data which demonstrates a tendency for the Bioconcentration Factor (BCF) to decrease as Log Pow increases above 6. This assumption is further confirmed by the data set available on “white oils” which demonstrates that they are poorly absorbed, and are not bioaccumulative in mammals. 

REGULATION (EC) No 1272/2008 as amended by COMMISSION REGULATION (EU) No 286/2011 of 10 March 2011 states as follows when deciding the criteria for bioaccumulation potential:

 

Cases when data do not allow classification under the above criteria but there are nevertheless some grounds for concern. This includes, for example, poorly soluble substances for which no acute toxicity is recorded at levels up to the water solubility (note 3), and which are not rapidly degradable and have an experimentally determined BCF500 (or, if absent, a log Kow4), indicating a potential to bioaccumulate, will be classified in this category unless other scientific evidence exists showing classification to be unnecessary. Such evidence includes chronic toxicity NOECs > water solubility or > 1 mg/l, or evidence of rapid degradation in the environment.

 

It is considered that sufficient evidence exists for avoidance of classification for bioaccumulative effects. White oils are not absorbed within the body, nor do they demonstrate any toxicity to mammalian or environmental organisms. As such, the “high” calculated Log Kow value associated with these types of substances is not proposed to be indicative of the propensity of the substance to become bioaccumulated. No classification is proposed on this basis.

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 May 2015
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was significantly more difficult than for a “standard” chemical, hence the methodology needed to be adapted for this special case. Although the analytical methods were not fully validated in GLP terms, the study outcome is considered to be probably as reliable as a fully GLP study using the same methodology.
Qualifier:
according to
Guideline:
other: None specified
Deviations:
not specified
Principles of method if other than guideline:
The solid phase extraction enrichment method failed because during the elution step interfering components were mobilized from the SPE tubes.The liquid-liquid extraction, evaporation and reconstitution is promising procedure but the sample preparation needs extra care.The sensitivity of the method was increased 10x without any technical difficulties in heptane solvent.
GLP compliance:
no
Remarks:
Although the analytical methods were not fully validated in GLP terms, the study outcome is considered to be probably as reliable as a fully GLP study using the same methodology.
Type of method:
other: solid phase extraction enrichment method and liquid-liquid extraction, evaporation and reconstitution procedure
Partition coefficient type:
octanol-water
Analytical method:
gas chromatography
Type:
log Pow
Partition coefficient:
> 5.31
Remarks on result:
other: Temp. & pH not reported. Due to the UVCB nature of the substance it is not possible to derive a definitive value.
Details on results:
Results of 1-octanol phase analysisThere were no significant concentration changes observed during the partition experiment.Results of aqueous phasesThe quantitative evaluation of the aqueous phase data was not successful, therefore so the analysis was repeated with 10 x higher injection volume (0.5 μL → 5.0 μL).Results of the repeated analytical measurementAs the injection volume was increased to 5.0 μL the calibration range was set to 0.05 – 1.00 mg/mL (these limits correspond to approx. 0.0017 – 0.033 mg/L concentration in the aqueous phase before the enrichment step). The blank and the 0.05 mg/mL calibration solution are compared in Fig. 9 (S/N for the 4.91 min peak is 6.7).-The analytical method was not validated and measured values were very close to the lower limit of calibration and the RSD values were high.-When the water fraction samples were evaporated, there was a significant amount of Octanol present in the residual sample (Octanol is soluble in water at about 0.46 g/L (CRC Handbook of Chemistry and Physics, CRC Press)-The resulting POW values should be considered as good estimation of the partition in the test system.

ENRICHMENT BY LIQUID-LIQUID EXTRACTION

Results of solubility in Water

Sample name

coil

in Sample (mg/mL)

in Water (mg/L)

Mean in Water (mg/L)

RSD (%)

Sample-01

5.43

0.54

0.49

15.1

Sample-02

4.38

0.44

 

DETERMINATION OF WATER SOLUBILITY

Results of solubility in Water

Sample name

coil(mg/L)

Average

caverage(mg/L)

RSD (%)

Sample-01-TOP

0.64

0.67

11.6

Sample-01-MID

0.75

Sample-01-BOT

0.61

Sample-02-TOP

0.68

0.59

12.0

Sample-02-MID

0.56

Sample-02-BOT

0.55

 

PARTITION COEFFICIENT

Results of 1-octanol phase samples

Sample name

coil measured(mg/mL)

Average

Recovery (%)

RSD%

Solvent Blank

-

N/A

N/A

N/A

c0-1

1.04

N/A

N/A

N/A

c0-2

2.11

N/A

N/A

N/A

Sample-01-1-Rec

0.96

1.03

99.7

9.6

Sample-01-2-Rec

1.10

Sample-02-1-Rec

2.17

2.21

104.7

2.0

Sample-02-2-Rec

2.24

 

Results of aqueous phase samples

Sample

coil in octanol(mg/mL)

Sampling position

coil in water(mg/L)

coil average(mg/L)

RSD (%)

POW

Control

0

N/A

0.001

0.0015

14.88

N/A

Control

0

N/A

0.002

1

1

Bottom

0.004

0.0046

13.10

5.34

1

1

Top

0.005

2

1

Bottom

*0.010

2

1

Top

*0.002

3

2

Bottom

0.009

0.0105

18.47

5.28

3

2

Top

0.009

4

2

Bottom

0.013

2

2

Top

0.011

*The marked values were excluded from the evaluation.

Important notes:

-The analytical method was not validated and measured values were very close to the lower limit of calibration and the RSD values were high.

-When the water fraction samples were evaporated, there was a significant amount of Octanol present in the residual sample (Octanol is soluble in water at about 0.46 g/L (CRC Handbook of Chemistry and Physics, CRC Press)

-The resulting POW values should be considered as good estimation of the partition in the test system.

Conclusions:
It is concluded that the actual Log Pow of the test item is > 5.31, however due to the UVCB nature of the substance it is not possible to derive a definitive value.
Executive summary:

The measured water solubility of the test item is unexpectedly high (0.6 mg/L).

The solid phase extraction enrichment method failed because during the elution step interfering components were mobilized from the SPE tubes.

The liquid-liquid extraction, evaporation and reconstitution is promising procedure but the sample preparation needs extra care.

The sensitivity of the method was increased 10 x without any technical difficulties in heptane solvent.

During the POW experiment some unforeseen technical and analytical difficulties appeared but the best estimation of the partition coefficient was performed. The two initial level experiments resulted 5.34 and 5.28 for log Pow.

The Log Pow measurement was made following the addition of 1 or 2 g test item per Litre of 1-octanol with 1:10 Octanol:water ratio. The water and octanol fractions were analysed for the test item. The recovery of test item from Octanol was approximately 100% (99.7% and 104.7% for 1 g/L and 2 g/L respectively). The recovery of test item in the water phase had some issues: Due to the solubility of octanol in water, there was approximately 10 times as much octanol in the evaporated water sample as there was test item, and the test item amount was close to the LOQ. It was concluded, based on the data that the water concentrations of test item were 0.0046 and 0.0105 mg/L at 1 and 2 g/L (initial octanol concentration) respectively. This a gave a theoretical Log Pow value of 5.31; however, since there was approximately 10 times as much Octanol as test item present in the water fraction, is likely that the presence of the Octanol would have resulted in a higher partition concentration of test item than it would be in pure water. Hence it is concluded that the actual Log Pow of the test item is > 5.31, however due to the UVCB nature of the substance it is not possible to derive a definitive value.

The study was significantly more difficult than for a “standard” chemical, hence the methodology needed to be adapted for this special case. Although the analytical methods were not fully validated in GLP terms, the study outcome is considered to be probably as reliable as a fully GLP study using the same methodology.

Description of key information

Partition Coefficient estimated via QSAR and modified study which is was comparable to recognised guidelines

Key value for chemical safety assessment

Log Kow (Log Pow):
31.33
at the temperature of:
25 °C

Additional information

The substance is a hydrocarbon UVCB. Standard tests for partition coefficient are intended for single substances and are not appropriate for this complex substance. It is unlikely that a study result would give anything other than a “greater than” limit value of the highest value available in the test. This endpoint is therefore characterized using quantitative structure property relationships for representative hydrocarbon structures that could be present within this UVCB substance. 70 proposed molecules are assessed, in order to provide a suitable range of likely values associated with the substance.

Using the US EPA On-Line EPI Suite™ KOWWIN version 1.68 model, the log Kow range is predicted to be 7.49 to 31.33. This indicates that the substance in theory could have the potential to bioaccumulate.  The substance is, however, considered to be not bioavailable to aqueous organisms as demonstrated by both the lack of acute toxicity and any associated adverse effects in the acute toxicity studies on aquatic organisms. Furthermore, the high log Pow is considered to be more a consequence of poor water solubility than a lipophilic tendency and is considered to be not indicative of the tendency to bioaccumulate in lipid tissues of aquatic organisms. This is based in part on an evaluation of literature data which demonstrates a tendency for the Bioconcentration Factor (BCF) to decrease as Log Pow increases above 6. This assumption is further confirmed by the data set available on “white oils” which demonstrates that they are poorly absorbed, and are not bioaccumulative in mammals. 

The UVCB test item was analysed by extracting the aqueous samples then evaporating the extraction solvent (n-heptane) and finally dissolving in a small volume of n-heptane, with GC-FID detection (optimised for maximum sensitivity) and integration of the main peaks.

It is concluded that the actual Log Pow of the test item is > 5.31, however due to the UVCB nature of the substance it is not possible to derive a definitive value.

The study was significantly more difficult than for a “standard” chemical, hence the methodology needed to be adapted for this special case. Although the analytical methods were not fully validated in GLP terms, the study outcome is considered to be probably as reliable as a fully GLP study using the same methodology.

REGULATION (EC) No 1272/2008 as amended by COMMISSION REGULATION (EU) No 286/2011 of 10 March 2011 states as follows when deciding the criteria for bioaccumulation potential:

 

Cases when data do not allow classification under the above criteria but there are nevertheless some grounds for concern. This includes, for example, poorly soluble substances for which no acute toxicity is recorded at levels up to the water solubility (note 3), and which are not rapidly degradable and have an experimentally determined BCF500 (or, if absent, a log Kow4), indicating a potential to bioaccumulate, will be classified in this category unless other scientific evidence exists showing classification to be unnecessary. Such evidence includes chronic toxicity NOECs > water solubility or > 1 mg/l, or evidence of rapid degradation in the environment.

 

It is considered that sufficient evidence exists for avoidance of classification for bioaccumulative effects. White oils are not absorbed within the body, nor do they demonstrate any toxicity to mammalian or environmental organisms. As such, the “high” calculated Log Kow value associated with these types of substances is not proposed to be indicative of the propensity of the substance to become bioaccumulated. No classification is proposed on this basis.