Reaction Mass of 1,4-dimethyl-7-(prop-1-en-2-yl)-1,2,3,4,5,6,7,8-octahydroazulene and 3,8-dimethyl-5-(prop-1-en-2-yl)-1,2,3,3a,4,5,6,7-octahydroazulene and 4,8a,9,9-tetramethyldecahydro-1,6-methanonaphthalen-1-ol

Bioaccumulation: aquatic / sediment

Description of key information

The registered substance “Reaction Mass of 1,4-dimethyl-7-(prop-1-en-2-yl) -1,2,3,4,5,6,7,8-octahydroazulene and 3,8-dimethyl-5-(prop-1-en-2-yl) -1,2,3,3a,4,5,6,7-octahydroazulene and 4,8a,9,9-tetramethyldecahydro-1,6-methanonaphthalen-1-ol” consists of constituents that have different physicochemical properties and different environmental fate behaviour.  As such a BCF test on the "whole substance" is considered scientifically unjustified and technically not feasible. Instead the range of log Kow values determined by the HPLC method (OECD 117) is used to assess the bioaccumulation potential for classification and PBT assessment purposes. For the chemical safety assessment, key constituents have been identified that represent the blocks of related constituents in the mixture. Using predicted BCF values for these representative constituents (see separate study records for QSAR prediction details), the chemical safety assessment does not show a need for further refinement. Therefore, the available information is deemed sufficient for classification purposes, the PBT assessment and the chemical safety assessment and no further testing is required. 

Since a significant fraction of Patchouli ext. has partition coefficients greater than 5.7, the substance is considered to be potentially bioaccumulative for classification and PBT assessment purposes. Reasonable conservative BCF estimates for the three major constituents were used for the CSA. Separate end-point summaries have been created for entering these key values. This endpoint summary is for Patchouli alcohol, which represents sesquiterpene alcohols, estimated BCF = 346.

Key value for chemical safety assessment

BCF (aquatic species):

346

Additional information

According to REACH Annex IX, information on bioaccumulation in aquatic species, preferably fish, is required for substances manufactured or imported in quantities of 100 t/y or more unless the substance has a low potential for bioaccumulation (for instance a log Kow ≤ 3). However, REACH aims to reduce animal testing where possible and according to the Integrated Testing Strategy (ITS, Figure R.7.10-2) in ECHA Guidance R.7c (Endpoint specific guidance), all available information should be assessed before further testing for bioaccumulation is performed. Furthermore, complex mixtures pose a special challenge to bioaccumulation assessment, because of the range of individual substances that may be present, and the variation in their physico-chemical and environmental fate properties. In such cases, it may be possible to screen for bioaccumulation potential by deriving a range of Kow values from a HPLC method. It is preferable to identify one or more constituents for further consideration that can be considered representative of other constituents in the mixture in terms of bioaccumulation potential.

Patchouli Oil is a multi-constituent substance consisting of sesquiterpene hydrocarbons and sesquiterpene alcohols. The HPLC method (OECD 117) was used to determine the partition coefficient. The HPLC chromatogram of the test material showed a large number of peaks, ten of which had relative peak areas of more than 1%. The first group of peaks (peaks 1 to 3) were determined to have log Kow values of 3.2, 4.5 and 5.0. Another group of peaks (peak 4 to 10) were found to have partition coefficients above the highest limit of the calibration range (i.e. > 5.7). Since a significant fraction of Patchouli Oil has partition coefficients > 5.7, the substance is considered to have the potential to bioconcentrate for classification purposes ( CLP Regulation EC 1272/2008 cut-off value of ≥ 4) and to meet the screening bioaccumulation criterion (logKow > 4.5) for PBT/vPvB assessment purposes.

For the chemical safety assessment, 3 key constituents have been identified that represent blocks of related constituents in Patchouli Oil in order to assess environmental exposure and risk.The BCF for each constituent was estimated using a consensus modelling approach using the BCF models available in BCFBAF v3.01. The Arnot-Gobas model assumes default lipid contents of 10.7%, 6.85% and 5.98% for the upper, middle and lower trophic levels. For regulatory purposes, the predicted BCF values have been corrected to a lipid content of 5%. This is the average lipid content of small fish used in the OECD 305 and the common lipid basis used for bioaccumulation assessment under REACH (ECHA Guidance R.7.10.4.1 and R.11.1.3.2). The results are summarised in the table below:

Constituent	Predicted BCF (BCFBAF v 3.01)
	Regression based estimate	Arnot-Gobas (upper trophic)^a		Arnot-Gobas (mid trophic)^a			Arnot-Gobas (lower trophic)^a			Arnot-Gobas (upper trophic)^b
		Model output^c	Corrected to 5% lipid content	Model output^d	Corrected to 5% lipid content	Model output^e		Corrected to 5% lipid content	Model output^c		Corrected to 5% lipid content
alpha-bulnesene CAS 3691-11-0 C(CC1C)C(=C(CC2)C)C1CC2C(=C)C	7706	11590	5416	16160	11796	17580		14699	19700		9206
alpha-guaiene CAS 3691-12-1 C(=C(C(CCC1C(=C)C)C)CC2)(C2C)C1	12960	9654	4510	14110	10299	15670		13102	15600		7290
Patchouli alcohol CAS 21682-90-6 CC1(C2CC3C(CCC1(C3(CC2)C)O)C)C	197	497	232	441	322	414		346	997		466

a) Including biotransformation rate estimates; b) Assuming a biotransformation rate of zero; c) 10.7% lipid; d) 6.85% lipid; e) 5.98% lipid

 

The BCFBAF regression-based QSAR for non-ionic substances with a log Kow of 1.0 to 7.0 is based on a large dataset of 396 while the Arnot-Gobas BCF & BAF method is considered to have wide applicability to non-ionic organic substances with a log Kow of < 9 and was calibrated to a large database of high quality BCF and BAF observations (482 and 936 respectively).

The three constituents fall within the applicability domain of both models. They are non-ionic and have estimated log Kow values (e.g. patchouli alcohol = 3.98, alpha-bulnesene = 6.40, alpha-guaiene = 6.74) which are within the log Kow applicability domain of both models. 

Models that do not account for biotransformation (e.g. the regression based estimate and Arnot-Gobas, upper trophic, assuming a biotransformation rate of zero) are generally considered to give conservative maximum estimates.  Model predictions (including biotransformation rate estimates) are generally considered more relevant and reliable. The different estimates obtained from the three general trophic levels of fish, even after correction to 5% lipid content, probably reflect different assumptions regarding body size. To this end, it is considered most appropriate to use the highest predicted values from these models (i.e. from the Arnot-Gobas with biotransformation estimates and corrected to 5% lipid) as reasonable conservative estimates, which are:

• alpha-bulnesene: represents sesquiterpene hydrocarbons with higher boiling point, estimated BCF = 14699


• alpha-guaiene: represents sesquiterpene hydrocarbons with lower boiling point, estimated BCF = 13102


• Patchouli alcohol: represents sesquiterpene alcohols, estimated BCF = 346

Using these BCF values, the chemical safety assessment does not show a need for further refinement. Therefore, the available information is deemed sufficient for classification purposes, the PBT assessment and the chemical safety assessment and no further testing is required.