Resinoid of Abies balsamea (Pinaceae) obtained from needles by an organic solvent extraction

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Justification for type of information:

The substance is a complex mixture, which contains a large number of constituents, which are mostly unkown but which have different solubility (often low solubility) and volatility. In addition its physical state leads to difficulties for physico-chemical testing: It is described as a dark green resinous material.
A GLP study has been conducted on similar substances (labdanum resinoid, for example and other resinoids) according to OECD 117 showing that this method is not applicable for such complex substances (the major peak of labdanum resinoid detected with a logKow < 0.3 while the substance is mainly not soluble in water or a very low response of test item with the HPLC detectors tested (Diode Array Detector and Mass Spectrometry) was obtained on other resinoids).
In addition, the physical state and the limited knowledge of the composition of such substances lead to technical issues to quantify the substance dissolved in water or in octanol media (GC/FID does not allow to detect the totality of the test item constituents). Then OCDE 107 and 123 are also considered as not appropriate.
That was reported in a feasibility study conducted on other resinoids.
Therefore conventional standard tests for partition coefficient endpoint intended for single substances are considered as not appropriate for such complex substances.
That is why the test has been waived for the registered substance.

Reference 2

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Study period:

run on 2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Justification for type of information:

QSAR prediction : The values obtained on known constituents of the substance are not experimental results, however the QSAR model is recommended by the ECHA guidance document on information requirements, is well documented with regard to validation parameters according to OECD principles. Moreover, the constituents of the substance are fully characterised towards the applicability domain.

Reason / purpose for cross-reference:

reference to other study

Principles of method if other than guideline:

QSAR estimation

Partition coefficient type:

octanol-water

Type:

log Pow

Partition coefficient:

>= -0.14 - <= 9.7

Remarks on result:

other: Temperature and pH not provided (QSAR estimation)

Remarks:

Range of logKow estimated on a the known constituents of the substance

Temperature and pH values are not considered in this model.

The estimation is based on the non-ionised form of the molecule.

No Experimental Value Adjustment was made.

The molecular weight of the constituents are between 126.11 and 204.36 g/mol, hence within the estimation domain of the validation set (27.03 -991.15 g/mol), all the functional groups are included in the list of descriptors, and, the occurence of each fragment is below the maximum number in the training/validation sets (Appendix D), such as:

		Training Set		Validation Set
Fragment Descriptor & Correction Factor Descriptor	Coef	Max	Number	Max	Number
-CH3 [aliphatic carbon]	0,5473	13	1401	20	7413
-CH2-   [aliphatic carbon]	0,4911	18	1083	28	7051
-CH   [aliphatic carbon]	0,3614	16	460	23	3864
=CH- or =C<  [olefinc carbon]	0,3836	10	239	10	1847
-tert Carbon [3 ot more carbon attach]	0,2676	4	130	8	1381
Fused aliphatic ring unit correction	-0,3421	8	41	8	684
-OH   [hydroxy, aliphatic attach]	-1,4086	6	187	9	1525
-C(=O)O [ester, aliphatic attach]	-0,9505	3	113	6	1178
=CH2 [olefinic carbon]	0,5184	2	50	4	235
-OH [alcohol, olefinic attach]	-0,8855	2	6	2	92
-C(=O)- [carbonyl, olefinic attach]	-1,27	2	43	2	401
-O-   [oxygen, two olefinic attach]	-0,35	0	4	1	15

Conclusions:

Log Kow of known constituents of the substance, representing a limited fraction of the composition, were estimated to be between -0.19 and 7.12 (estimated by QSAR)

Executive summary:

The partition coefficient of the known constituents of the substance were estimated using the recommended QSAR model KOWWIN v1.68, based on Atom/Fragment Contribution (AFC) method. The constituents of the test item were within the applicability domain (MW, descriptors).

This range of logKow was estimated between -0.19 and 7.12, with a standard deviation provided by the model of 0.48.

Description of key information

No range of logKow representative of the test item can be determined (neither with an experimental approach nor with an estimation approach)

Additional information

The substance is a complex mixture, which contains a large number of constituents, which are mostly unkown but which have different solubility (often low solubility) and volatility. In addition the physical state of such complex substances leads to difficulties for physico-chemical testing: fir balsam resinoid is described as a dark green resinous material.

A study has been conducted according to OECD 117 on other resinoids, which lead to a non reliable result (logKow < 0.3 while the substance is mainly insoluble in water), showing that this method is not applicable for such complex substances. In addition, the physical state and the limited knowledge on the composition of such substances lead to technical issues to quantify the substance dissolved in water or in octanol media. Then OCDE 107 and 123 are also considered as not appropriate.

Finally conventional standard tests for partition coefficient endpoint intended for single substances are considered as not appropriate for such complex substances.

That is why the test has been waived for the registered substance.

In addition calculated values were provided on known constituents of the substance. However, only a range of logKow on a limited part of the composition of the substance can be calculated using QSAR estimations.

Therefore it is considered that no range logKow representative of the whole test item can be determined (neither with an experimental approach nor with an estimation approach).