(R)-5-isopropyl-2-methylcyclohexa-1,3-diene

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Study period:

2018-03

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:

Please refer to the QMRF and QPRF files provided under the section attached justification.

Principles of method if other than guideline:

Estimation of BCF, BAF and biotransformation rate using BCFBAF v3.01

GLP compliance:

no

Specific details on test material used for the study:

SMILES: C1=C(C)C=CC(C(C)C)C1

Test organisms (species):

other: fish

Details on estimation of bioconcentration:

BASIS INFORMATION
- Measured logPow: 5.74

BASIS FOR CALCULATION OF BCF
- Estimation software: BCFBAF Program (v3.01), EpiSuite v4.11
- Result based on measured log Pow of: Estimated Log BCF = 3.454 (BCF = 2846 L/kg wet-wt)

Key result

Type:

BCF

Value:

2 846 L/kg

Basis:

not specified

Remarks on result:

other: The substance is within the applicability domain of the BCFBAF submodel: Bioconcentration factor (BCF; Meylan et al., 1997/1999).

Details on kinetic parameters:

Biotransformation half-life (days): 6.717
Biotransformation rate (kM, normalised to 10 g fish at 15 °C): 0.1032
The substance is within the applicability domain of the BCFBAF submodel: Biotransformation rate in fish (kM; Arnot et al., 2008a/b).

BCFBAF Program (v3.01) Results:

SMILES : C1=C(C)C=CC(C(C)C)C1

CHEM  : 1,3-Cyclohexadiene, 2-methyl-5-(1-methylethyl)-, (R)-

MOL FOR: C10 H16

MOL WT : 136.24

Summary Results

Log BCF (regression-based estimate): 3.45 (BCF = 2.85e+003 L/kg wet-wt)

Biotransformation Half-Life (days) : 6.72 (normalized to 10 g fish)

Log BAF (Arnot-Gobas upper trophic): 3.67 (BAF = 4.64e+003 L/kg wet-wt)

 

Log Kow (experimental): not available from database

Log Kow used by BCF estimates: 5.74 (user entered)

 

Equation Used to Make BCF estimate:

Log BCF = 0.6598 log Kow - 0.333 + Correction

 

Correction: No Applicable Correction Factors

 

Estimated Log BCF = 3.454 (BCF = 2846 L/kg wet-wt)

 

Whole Body Primary Biotransformation Rate Estimate for Fish:

TYPE	NUM	LOG BIOTRANSFORMATION FRAGMENT DESCRIPTION	COEFF	VALUE
Frag	3	Methyl [-CH3]	0.2451	0.7353
Frag	1	-CH- [linear]	-0.1912	-0.1912
Frag	1	-CH2- [cyclic]	0.0963	0.0963
Frag	1	-CH - [cyclic]	0.0126	0.0126
Frag	3	-C=CH [alkenyl hydrogen]	0.0988	0.2965
Frag	3	-C=CH [alkenyl hydrogen]	0.0000	0.0000
L Kow	*	Log Kow = 5.74 (user-entered)	0.3073	1.7641
MolWt	*	Molecular Weight Parameter		-0.3494
Const	*	Equation Constant		-1.5371
RESULT	LOG Bio Half-Life (days)			0.8272
RESULT	Bio Half-Life (days)			6.717
NOTE	Bio Half-Life Normalized to 10 g fish at 15 deg C

Biotransformation Rate Constant:

kM (Rate Constant): 0.1032 /day (10 gram fish)

kM (Rate Constant): 0.05803 /day (100 gram fish)

kM (Rate Constant): 0.03263 /day (1 kg fish)

kM (Rate Constant): 0.01835 /day (10 kg fish)

 

Arnot-Gobas BCF & BAF Methods (including biotransformation rate estimates):

Estimated Log BCF (upper trophic) = 3.355 (BCF = 2263 L/kg wet-wt)

Estimated Log BAF (upper trophic) = 3.666 (BAF = 4639 L/kg wet-wt)

Estimated Log BCF (mid trophic)  = 3.477 (BCF = 3002 L/kg wet-wt)

Estimated Log BAF (mid trophic)  = 3.983 (BAF = 9612 L/kg wet-wt)

Estimated Log BCF (lower trophic) = 3.511 (BCF = 3245 L/kg wet-wt)

Estimated Log BAF (lower trophic) = 4.187 (BAF = 1.539e+004 L/kg wet-wt)

 

Arnot-Gobas BCF & BAF Methods (assuming a biotransformation rate of zero):

Estimated Log BCF (upper trophic) = 4.275 (BCF = 1.884e+004 L/kg wet-wt)

Estimated Log BAF (upper trophic) = 6.120 (BAF = 1.317e+006 L/kg wet-wt)

Validity criteria fulfilled:

yes

Conclusions:

Using BCFBAF v3.01 the BCF value of the test item was calculated to be 2846.0 L/kg. The substance is within the applicability domain of the model.

Executive summary:

The BCF value was calculated using BCFBAF v3.01 as part of EPISuite v4.11 from US Environmental Protection Agency. The BCF value of the test item was calculated to be 2846.0 L/kg (EPI Suite, 2014).

The adequacy of a prediction depends on the following conditions:

a) the (Q)SAR model is scientifically valid: the scientific validity is established according to the OECD principles for (Q)SAR validation;

b) the (Q)SAR model is applicable to thequery chemical: a (Q)SAR is applicable if the query chemical falls within the defined applicability domain of the model;

c) the (Q)SAR result is reliable: a valid (Q)SAR that is applied to a chemical falling within its applicability domain provides a reliable result;

d) the (Q)SAR model is relevant for theregulatory purpose.

 

For assessment and jsutification of these 4 requirements the QMRF and QPRF files were developed and attached to this study record.

 

Description of the prediction Model

The prediction model was descripted using the harmonised template for summarising and reporting key information on (Q)SAR models. For more details please refer to the attached QSAR Model Reporting Format (QMRF) file. 

 

Assessment of estimation domain

The assessment of the estimation domain was documented in the QSAR Prediction Reporting Format file (QPRF). Please refer to the attached document for the details of the prediction and the assessment of the estimation domain.

Description of key information

The BCF of the substance was calculated to be 2846.0 L/kg (worst case value from different QSARS).

Key value for chemical safety assessment

BCF (aquatic species):

2 846 L/kg ww

Additional information

Discussion

The bioconcentration factor of the test item for aquatic species (fish) was calculated by three different QSAR models (US EPA T.E.S.T. v4.2.1, EPIWIN BCFBAF v3.01 and VEGA v1.1.4 CAESAR v2.1.14) falling in its applicability domain. The results of the QSAR predictions were assessed in a weight of evidence approach, following worst case assumption.

Using BCFBAF v3.01 the BCF value of the test item was calculated to be 2846.0 L/kg. The substance is within the applicability domain of the model.

Using T.E.S.T. v4.2.1 the BCF value of the test item was calculated to be 714.42 L/kg. The substance is within the applicability domain of the model.

Using VEGA v1.1.4 (CAESAR v2.1.14) the BCF value of the test item was calculated to be 233 L/kg. The substance is within the applicability domain of the model.

In a worst-case approach, the BCF of the test item was determined to be 2846.0 L/kg (value calculated with BCFBAF v3.01). According to section 1 of Annex XIII to the Regulation (EC) 1907/2006 (REACH), this result passes the threshold value for bioaccumulative properties of >2000 L/kg, but it does not fulfil the vB criterion of  > 5000 L/kg. The values determined by the QSAR models US EPA T.E.S.T. v4.2.1 and  VEGA v1.1.4 (714.42 L/kg and 233 L/kg, respectively), even fall below the B criterion of > 2000 L/kg and thus, they do not indicate a bioaccumulative potential of the substance (neither vB nor B). In conclusion, following a conservative approach, the substance is considered to be bioaccumulative (B), but not very bioaccumulative (vB) according to Regulation (EC) 1907/2006.

QSAR-disclaimer

 

In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met. Furthermore according to Article 25 of the same Regulation testing on vertebrate animals shall be undertaken only as a last resort.

 

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.

 

For the assessment of bioaccumulation potential, (Q)SAR results were used for bioaccumulation: aquatic / sediment. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint is sufficiently covered and suitable for risk assessment.

 

Therefore, further experimental studies on bioaccumulation are not provided.