Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
Not relevant
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 adequate and reliable documentation / justification
Justification for type of information:
Petitgrain oil - citrus aurantum is an UVCB substance. Regarding the different solubility of its constituents that make the testing difficult and a known fraction >90%, calculation from the predicted biodegradability of the known constituent appears as an acceptable approach.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Principles of method if other than guideline:
This calculation method uses the model CATALOGIC Kinetic 301F v.13.16 within LMC OASIS CATALOGIC v5.11.19 to predict, based on the known constituents, the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following the Guideline for Testing of Chemicals No. 301F, "Ready Biodegradability, Manometric Respirometry method", referenced as Method C.4-D of Commission Regulation No. 440/2008.
GLP compliance:
no
Remarks:
Not required for a calculation based on multiple QSARs method.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: not applicable for in silico study
Details on test material:
- Name of test material (as cited in study report): Petitgrain oil
- Commercially available test material - not applicable for in silico study
Specific details on test material used for the study:
Composition of the Essential oil from the leaves and twigs of Citrus aurantium (Rutaceae) obtained by distillation (PETIT GRAIN):
Limonene (d and l) 2%
Pinene alpha + beta 1.2%
Caryophyllene beta 1%
Linalol 25%
Ocimene (cis + trans) 3.5%
Terpineol alpha 5.5%
Geranyl acetate 4%
Geraniol 3%
Nerol 1%
Linalyl acetate 48%
Neryl acetate 2%
Myrcene beta 2.5%

Study design

Oxygen conditions:
aerobic

Results and discussion

% Degradation
Key result
Parameter:
% degradation (O2 consumption)
Value:
0.74
St. dev.:
0.04
Sampling time:
28 d
Remarks on result:
readily biodegradable based on QSAR/QSPR prediction
Details on results:
The prediction of the biodegradability of the mixture is based on:

 On the observed biodegradability of the constituents that are part of the training set
Chem. Name BOD_Observed [28d] * predicted BOD [28d]
Linalol 0.789 0.76
Geraniol 0.882 0.8
Nerol 0.882 0.8
Linalyl acetate 0.609 0.76
Ocimene 0.3 0.4
*part of the training set, used for the prediction of the mixture

 On the predicted biodegradability of the constituents that are not part of the training set. In the case of pinene, which is known to be biodegradable (but not part of the training set), the prediction is that pinene biodegrades at 55% (0.55), it is not possible to overwrite the prediction. This results in an underestimation of the prediction of the overall biodegradability of the essential oil.
Chem. Name predicted BOD [28d]* Measured biodegradation
Pinene (alpha & beta) 0.55 76% at 28d in 301D#

* used for the prediction of the mixture
#not part of the training set, not considered in the overall prediction of biodegradability of the mixture.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
QSAR model validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004).
Interpretation of results:
readily biodegradable
Conclusions:
The assessment indicates that the prediction on the biodegradation potential of the essential oil PETIT GRAIN is suitable for the regulatory purpose (address the information requirement for REACH Regulation (EC) 1907/2006: Annex VII – Section 9.2.1.1 (Ready Biodegradability) and contribute to the assessment for Classification and Labelling: part 4 Environmental Hazards; under CLP Regulation (EC) 1272/2008). Conclusion of this constituent approach based on the QSAR generated with CATABOLIC is that the essential oil PETIT GRAIN 28-day BOD is 74% ± 4%, and therefore that PETIT GRAIN oil meets the criteria to be qualified as readily biodegradable.
Executive summary:

Based on a constituent approach including all constituents equal or above 1%, which biodegradation are predicted by using the expect system CATALOGIC Kinetic 301F v.13.16, the Biochemical Oxygen Demand after 28 days is estimated 74% ± 4%, and therefore the UVCB Petitgrain oil concluded as meeting the criteria to be qualified as readily biodegradable. All the constituents are within the applicability domain of the model. In addition, 5 among 12 are part of the training set and confirm that the predicted biodegrabilities are equivalent to test results. For Pinene alpha & beta (1.2%) for which the model predicted only 55% biodegrability, whereas ready biodegradable could be concluded based on the OECD301D test result reported on ECHA website for the registered substance (-)-pin-2(3)-ene. As it is not possible to overwrite the prediction, this results in an underestimation of the overall biodegradability of the essential oil.