Ethylenebis(oxyethylene) bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate]

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1981-10-27 to 1981-12-26

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP study with analytical monitoring

Qualifier:

according to guideline

Guideline:

OECD Guideline 305 C (Bioaccumulation: Test for the Degree of Bioconcentration in Fish)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Bioaccumulation study of chemical substance in fish body; Testing methods relating New Chemical Substances (Kanpogyo No. 5, Yakuhatsu No. 615, 49 Kikyoku No. 392, July 13, 1974 )

Deviations:

no

GLP compliance:

no

Radiolabelling:

no

Details on sampling:

- Sampling intervals/frequency for test organisms: day 3, 7, 14, 21, 28, 42 and 56
- Sampling intervals/frequency for test medium samples: day 0, 3, 7, 14, 21, 28, 35, 42, 49 and 56
- Details on sampling and analysis of test organisms and test media samples (e.g. sample preparation, analytical methods):
test organisms: After determination of bodyweight the test fish was minced. Afterwards 80 mL acetone and 80 ml chloroform was added, homogenizated for for 10 min and filtered. This procedure was repeated 3 times. The filtrate was evaporated using a rotary evaporator and 70 mL acetonitrile and 70 mL n-hexane was added. This solution was evaporated and 50 ml water and 50 mL ethyl acetat was added. The acetonitrile fraction was was evaporated using a rotary evaporator and clean up for the HPLC chronmatography.
Test water: test water sample was taken and 80 mL chloroform, 20 mL acetone und 1.0g NaCl were added and extratcted. This procedure was repeated 3 times. The chlrofom fraction were evaporated to solid dissolved in tetrahydrofuran and assayed by HPLC (recovery rate 86.8 %).

Vehicle:

yes

Details on preparation of test solutions, spiked fish food or sediment:

1.00 g of the test substance was weighed in a mortar, and tetrahydrofuran (10 mL) was added and mixed well. Melted hydrogenated castor oil (HCO-40, 10.0 g) was added, the mixture was stirred well with a pestle, tetrahydrofuran (2–3 mL) was added, and the mixture was homogenized. Next, sugar (10.0 g) was added a small amount at a time with further stirring. At this point, tetrahydrofuran was added in small amounts to homogenize the mixture as much as possible. The amount of tetrahydrofuran added did not exceed 20.0 mL. Then, hot ion-exchanged water was added gradually with thorough mixing to give a final volume of 1.0 L. This solution was used as the 1000-ppm (w/v) stock solution.

Test organisms (species):

Cyprinus carpio

Details on test organisms:

TEST ORGANISM
- Length at study initiation (lenght definition, mean, range and SD): 10.2 ± 0.5 cm
- Weight at study initiation (mean and range, SD): 28.1 ± 5.3 g
- Lipid content: 3.4 ± 0.8 %
- Description of housing/holding area: aquarium

ACCLIMATION
- Acclimation period: Fish were acclimated in an aquarium at 25°C for 20 days, following an external disinfection for 24 hours under static conditions.

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

8 wk

Test temperature:

21.5 ± 0.5 °C

pH:

first concentration: 7.1 - 7.2
second concentration: 7.0 - 7.1

Dissolved oxygen:

first concentration: 6.8 - 7.6
second concnetration: 6.8 - 7.5

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 100 L glass aquarium
- Renewal rate of test solution (frequency/flow rate): The stock solution and the dilution water were supplied to a test tank at rates of 300 mL/min.

RANGE-FINDING / PRELIMINARY STUDY
- Results used to determine the conditions for the definitive study: 48h TLm=45 ppm (determined with killifish)

Nominal and measured concentrations:

Two concentrations were tested: 0.7 ppm (1st conc. level) and 0.07 ppm (2nd conc. level)

Lipid content:

ca. 3.4 %

Time point:

start of exposure

Remarks on result:

other: Level area 1& 2

Type:

BCF

Value:

2 - 12

Basis:

whole body w.w.

Remarks on result:

other: second concentration

Remarks:

Conc.in environment / dose:0.07 ppm

Type:

BCF

Value:

0.11 - 2.45

Basis:

whole body w.w.

Remarks on result:

other: first concentration

Remarks:

Conc.in environment / dose:0.7 ppm

Test results   Bioconcentration factors	1st conc. level		1 wk	2 wk	4 wk	6 wk	8 wk
		Conc. ppm	0.63	0.62	0.63	0.65	0.65
		BCF	2.0	1.0	1.9	1.5	3.5
			1.7	2.0	1.3	2.1	1.9
	2nd conc. level	Conc. ppm	0.069	0.069	0.072	0.073	0.074
		BCF	3.3	8.8	3.5	10.6	6.5
			11.3	6.9	5.5	7.3	8.0

Executive summary:

At the end of an 8-week exposure period, the BCF at a concentration of 0.7 ppm was 3.5 and 1.9, and at a test article concentration of 0.07 ppm the BCF was 8.0 and 6.5.

Reference 2

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Study period:

2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
OASIS Catalogic v5.12.1

2. MODEL (incl. version number)
BCF base-line model v02.09 - July 2016

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See section 'Test Material'.

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF.

5. APPLICABILITY DOMAIN
See attached QPRF.

6. ADEQUACY OF THE RESULT
- The model is scientifically valid (see attached QMRF).
- The model estimates the Bioconcentration factor (BCF) as required information point according to Regulation (EC) No 1907/2006 [REACH], Annex IX, 9.3.2 Bioaccumulation in aquatic species (preferably fish);
further related predictions: Apparent effect of mitigating factors / Maximum bioconcentration factor (BCFmax) / Maximum diameter of energetically stable conformers / Whole body primary biotransformation half-life / Metabolic biotransformation rate constant Km / Metabolites and their quantitative distribution
- See attached QPRF for reliability assessment.

Principles of method if other than guideline:

Calculation using Catalogic v.5.12.1, BCF base-line model v.02.09

GLP compliance:

no

Details on estimation of bioconcentration:

BASIS FOR CALCULATION OF BCF
- Estimation software: OASIS Catalogic v5.12.1 [BCF base line model - v.02.09]

Key result

Type:

BCF

Value:

4.4 L/kg

Remarks on result:

other: considering all mitigating factors; the substance is not within the applicability domain of the model.

Type:

BCF

Value:

1 514 L/kg

Remarks on result:

other: without considering any mitigating factors; the substance is not within the applicability domain of the model.

Reference 3

Endpoint:

bioaccumulation in aquatic species, other

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification

Principles of method if other than guideline:

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

GLP compliance:

no

Test organisms (species):

other: fish

Details on estimation of bioconcentration:

BASIS INFORMATION
- Measured logPow: 4.7

BASIS FOR CALCULATION OF BCF
- Estimation software: BCFBAF v3.01
- Result based on measured log Pow of: 4.7

Type:

BCF

Value:

14.9

Basis:

not specified

Remarks on result:

other: The substance is within the molecular weight and logKow ranges of the applicability domain of the BCFBAF submodel: Bioconcentration factor (BCF; Meylan et al., 1997/1999). One of the fragments for the correction factors was exceeded.

Type:

BCF

Value:

12.58

Basis:

not specified

Calculation basis:

steady state

Remarks on result:

other: Upper trophic, incl. biotransformation estimates; The substance is within the applicability domain of the BCFBAF submodel: Arnot & Gobas BAF and steady-state BCF Arnot & Gobas, 2003).

Type:

BCF

Value:

4 554

Calculation basis:

steady state

Remarks on result:

other: Upper trophic, biotransformation rate of zero; The substance is within the applicability domain of the BCFBAF submodel: Arnot & Gobas BAF and steady-state BCF Arnot & Gobas, 2003).

Type:

BAF

Value:

12.58

Basis:

not specified

Remarks on result:

other: Upper trophic, incl. biotransformation estimates; The substance is within the applicability domain of the BCFBAF submodel: Arnot & Gobas BAF and steady-state BCF Arnot & Gobas, 2003).

Type:

BAF

Value:

33 570

Basis:

not specified

Remarks on result:

other: Upper trophic, incl. biotransformation rate of zero; The substance is within the applicability domain of the BCFBAF submodel: Arnot & Gobas BAF and steady-state BCF Arnot & Gobas, 2003).

Details on kinetic parameters:

Biotransformation half-life (days): 0.001076
Biotransformation rate (kM, normalised to 10 g fish at 15 °C): 25/day (Predicted value exceeds theoretical whole body maximum value. kM (Rate Constant) of 25 /day is recommended/applied for 10 g fish)
The substance is within the applicability domain of the BCFBAF submodel: Biotransformation rate in fish (kM; Arnot et al., 2008a/b).

Summary Results:

Log BCF (regression-based estimate): 1.17 (BCF = 14.9 L/kg wet-wt)

Biotransformation Half-Life (days) : 0.00108 (normalized to 10 g fish)

Log BAF (Arnot-Gobas upper trophic): 1.10 (BAF = 12.6 L/kg wet-wt)

 

Log Kow (experimental): not available from database

Log Kow used by BCF estimates: 4.70 (user entered)

 

Equation Used to Make BCF estimate:

Log BCF = 0.6598 log Kow - 0.333 + Correction

 

Correction(s):                   Value

Tert-Butyl ortho-phenol type   -0.222

Alkyl chains (8+ -CH2- groups) -1.374

 

Estimated Log BCF = 1.172 (BCF = 14.85 L/kg wet-wt)

 

Whole Body Primary Biotransformation Rate Estimate for Fish:

Type	Num	Log biotransformation fragment description	Coeff	Value
Frag	2	Aromatic alcohol [-OH]	-0.4727	-0.9455
Frag	2	Ester  [-C(=O)-O-C]	-0.7605	-1.5211
Frag	2	Carbon with 4 single bonds & no hydrogens	-0.2984	-0.5969
Frag	2	Aliphatic ether [C-O-C]	-0.0232	-0.0465
Frag	4	Alkyl substituent on aromatic ring	0.1781	0.7122
Frag	2	Aromatic-CH3	-0.0872	-0.1743
Frag	2	Aromatic-CH2	-0.3365	-0.6730
Frag	4	Aromatic-H	0.2664	1.0655
Frag	6	Methyl [-CH3]	0.2451	1.4706
Frag	8	-CH2- [linear]	0.0242	0.1935
Frag	2	Benzene	-0.4277	-0.8555
L Kow	*	Log Kow =  4.70 (user-entered  )	0.3073	1.4445
MolWt	*	Molecular Weight Parameter		-1.5047
Const	*	Equation Constant		-1.5371
Result	LOG Bio Half-Life (days)			-2.9680
Result	Bio Half-Life (days)			0.001076
Note	Bio Half-Life Normalized to 10 g fish at 15 deg C

 

Biotransformation Rate Constant:

kM (Rate Constant): 25 /day (10 gram fish) **

kM (Rate Constant): 14.06 /day (100 gram fish) **

kM (Rate Constant): 7.906 /day (1 kg fish) **

kM (Rate Constant): 4.446 /day (10 kg fish) **

 

** Predicted value exceeds theoretical whole body maximum value.

kM (Rate Constant) of 25 /day is recommended/applied for 10 g fish

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

Estimated Log BCF (upper trophic) = 1.100 (BCF = 12.58 L/kg wet-wt)

Estimated Log BAF (upper trophic) = 1.100 (BAF = 12.58 L/kg wet-wt)

Estimated Log BCF (mid trophic)  = 1.229 (BCF = 16.95 L/kg wet-wt)

Estimated Log BAF (mid trophic)  = 1.230 (BAF = 16.97 L/kg wet-wt)

Estimated Log BCF (lower trophic) = 1.269 (BCF = 18.58 L/kg wet-wt)

Estimated Log BAF (lower trophic) = 1.279 (BAF = 19.01 L/kg wet-wt)

 

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

Estimated Log BCF (upper trophic) = 3.658 (BCF = 4554 L/kg wet-wt)

Estimated Log BAF (upper trophic) = 4.526 (BAF = 3.357e+004 L/kg wet-wt)

 

Reference 4

Endpoint:

bioaccumulation in aquatic species, other

Type of information:

(Q)SAR

Remarks:

Migrated phrase: estimated by calculation

Adequacy of study:

weight of evidence

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

Principles of method if other than guideline:

T.E.S.T. is a toxicity estimation software tool. The program requires only the molecular structure of the test item, all other molecular descriptors which are required to estimate the toxicity are calculated within the tool itself. The molecular descriptors describe physical characteristics of the molecule (e.g. E-state values and E-state counts, constitutional descriptors, topological descriptors, walk and path counts, connectivity, information content, 2d autocorrelation, Burden eigenvalue, molecular property (such as the octanol-water partition coefficient), Kappa, hydrogen bond acceptor/donor counts, molecular distance edge, and molecular fragment counts). Each of the available methods uses a different set of these descriptors to estimate the toxicity.
The bioaccumulation factor (BCF) was estimated using several available methods: hierarchical clustering method; FDA method, single model method; group contribution method; nearest neighbor method; consensus method. The methods were validated using statistical external validation using separate training and test data sets.
The experimental data set was obtained from several different databases (Dimitrov et al., 2005; Arnot and Gobas, 2006; EURAS; Zhao, 2008). From the available data set salts, mixtures and ambiguous compounds were removed. The final data set contained 676 chemicals.

References:
- Dimitrov, S., N. Dimitrova, T. Parkerton, M. Combers, M. Bonnell, and O. Mekenyan. 2005. Base-line model for identifying the bioaccumulation potential of chemicals. SAR and QSAR in Environmental Research 16:531-554.
- Arnot, J.A., and F.A.P.C. Gobas. 2006. A review of bioconcentration factor (BCF) and bioaccumulation factor (BAF) assessments for organic chemicals in aquatic organisms. Environ. Rev. 14:257-297.
- EURAS. Establishing a bioconcentration factor (BCF) Gold Standard Database. EURAS [cited 5/20/09]. Available from http://www.euras.be/eng/project.asp?ProjectId=92.
- Zhao, C.; Boriani, E.; Chana, A.; Roncaglioni, A.; Benfenati, E. 2008. A new hybrid system of QSAR models for predicting bioconcentration factors (BCF). Chemosphere 73:1701-1707.

GLP compliance:

no

Test organisms (species):

other: fish

Details on estimation of bioconcentration:

BASIS FOR CALCULATION OF BCF
- Estimation software: US EPA T.E.S.T. v4.2.1

Applied estimation methods:
- Hierarchical clustering
- FDA
- Single model
- Group contribution
- Nearest neighbor
- Consensus

Key result

Type:

BCF

Value:

9.97 dimensionless

Remarks on result:

other: method: consensus (average of reasonable results from all models); log BCF = 1.00; Based on the mean absolute error, the confidence in the predicted BCF values is low.

Description of key information

The parent substance and its relevant metabolites do not significantly accumulate in aquatic organisms. 

Additional information

 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 CAS 36443-68-2 (Q)SAR results were used for bioaccumulation. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.

Therefore, and for reasons of animal welfare, further experimental studies on bioaccumulation are not provided.

 

 

Assessment for CAS 36443-68-2

The bioaccumulative potential of the substance was assessed in a weight of evidence approach including an experimental study and several QSAR calculations as well as information on the molecular dimensions.

The experimentally derived BCF value was determined to be 12 at a test concentration of 0.07 mg/L (water solubility of the substance 0.104 mg/L). The study was performed with the common carp according to OECD TG 305.

Several QSAR calculations have been performed to support the experimental result.

 

(1)  Catalogic v5.11.19, BCF base-line model v02.09

(2)  US EPA EPISuite v4.11, BCFBAF v3.01

(3)  US EPA T.E.S.T. v4.2.1

(4)  Vega v1.1.3 including CAESAR v2.1.14, Meylan v1.0.3 and Read-across/KNN v1.1.0

 

In regard to the reliability of the QSAR predictions the results from the models included in the Vega model were not taken into account for the general prediction because the substance was not within the applicability domain of the models.

The domain of the BCF base-line model implemented in Catalogic is divided in three sub-domains. (1) The parameter domain which compares the logKow, water solubility and molecular size of the substance to the specific ranges of the training set, (2) the structural fragment domain which compares the atom-centered fragments of the substance to the ones from the training set and (3) the mechanistic domain which evaluates the general uptake mechanism of the compound as only such chemicals which are taken up by passive diffusion can be predicted. The current substance was within the parameter and the mechanistic domain of the model. In regard to the structural domain, 87.5% of the fragments of the substance could be found in correctly predicted training chemicals. Only 12.5% of the fragments were not present in the training chemicals. Principally, the substance is not within the domain of the model as not all atom-centered fragments could be found in correctly predicted training chemicals, however, the result is regarded as reliable and adequate for the use in a weight of evidence approach. The predicted BCF value was determined to be 6.46 L/kg. Metabolism, size and to a minor extent water solubility were the most important mitigating factors decreasing the BCF value.

The US EPA’s EPISuite includes a regression-based BCF prediction and a prediction taking the biotransformation rate into account. Concerning the regression based prediction the compound was within the molecular weight and logKow ranges of the model. However, the maximum number of fragments was exceeded in one instance as the compound comprises two tert-butyl ortho phenol groups instead of one. Therefore, the result might be less reliable. Nevertheless, the result of the regression-based estimation was regarded as adequate in a weight of evidence approach. The model predicted the BCF with 14.9 L/kg. The second model takes the biotransformation of the compound into account. The substance was within the applicability domain of the model. A BCF of 12.58 L/kg (upper trophic level) was estimated.

US EPA’s T.E.S.T. model combines 5 methods in the consensus approach. The model only delivers results if the substance is in the applicability domain of the respective model. Except for the group contribution method, the compound was in domain of all the models included in the T.E.S.T. package. However, the confidence of the results is low due to the mean absolute error of the single results. Nevertheless, the results were regarded as reliable in a weight of evidence approach. The consensus approach resulted in a BCF value of 9.97.

In addition to the experimental and modelled BCF data, information on the molecular dimensions were used. According to ECHA's Guidance on Information Requirements and Chemical Safety Assessment, R.11: PBT Assessment, the capability of crossing biological membranes is hindered if the average maximum diameter is > 1.7 nm. The present substance has an average maximum diameter of 2.4 nm. Therefore, an uptake through biological membranes is not expected. 

In conclusion, in a weight of evidence approach using all available data, it can be concluded that the substance does not significantly accumulate in organisms.

 

Assessment of metabolites

 According to the results of Catalogic v5.14.1.5, CATALOGIC 301C v.11.16 (see chapter 5.2.1) 50 metabolites without the parent substance were predicted. Two of them were predicted to occur in quantities greater than 0.1 and had log Know greater than 4. Therefore, the metabolites No. 9 and 31 were further investigated for their bioaccumulation potential. Due to their log Kow < 4 no bioaccumulation in organisms is expected for the other predicted metabolites with quantities above 0.1 %. The main metabolite was identified as the free carboxylic acid, 3-(3-tert-butyl-4-hydroxy-5-methyl-phenyl)propanoic acid (No.9).

 

Assessment for the main metabolite (No. 9) of CAS 36443-68-2, i.e. 3-(3-tert-butyl-4-hydroxy-5-methyl-phenyl)propanoic acid

The main metabolite during degradation is the free carboxylic acid, 3-(3-tert-butyl-4-hydroxy-5-methyl-phenyl)propanoic acid. The parent compound was 100% within the AD. To further assess the bioaccumulative potential of this metabolite Catalogic v5.12.1, BCF base-line model v02.09 was used.

The compound is within the parameter ranges of the QSAR model, i.e. its water solubility, molecular weight and water solubility are within the ranges of the training set. It needs to be pointed out, that the prediction was conducted with the neutral molecule and the logKow of the neutral molecule. The compound is also within the mechanistic domain, i.e. the compound is taken up by passive diffusion only. Furthermore, it is within the structural domain by 75%. Only 25% of the fragments are not present in the training set.

The model predicted a BCF of 4.4 L/kg with all mitigating factors applied. The most influential mitigating factors were metabolism, acids, and size.

As the substance has a carboxylic acid moiety and a predicted pKa of 4.75 (SPARC accessed on November 14th, 2017) it is mostly present in its anionic form under environmental conditions (pH 5 to 9). Since the neutral and ionic species exhibit different polarities, the logKow value is pH dependent. Therefore, the logD is the more significant parameter. It ranges from 2.6 at pH 5 and decreases with increasing pH values. At pH 9 it is -0.9 which is well below the B threshold screening criterion of 4.5.

In addition and as supporting evidence to the assessment of 3-(3-tert-butyl-4-hydroxy-5-methyl-phenyl)propanoic acid there are experimental data available for CAS 20170-32-5; 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid. This compound comprises a tert-butyl instead of a methyl group at position 5. Nevertheless, its bioaccumulative potential is expected to be very similar and its use as supporting evidence in the assessment of the bioaccumulative potential of the main metabolite 3-(3-tert-butyl-4-hydroxy-5-methyl-phenyl)propanoic acid is justified. The available experimental study resulted in a BCF < 223 at a concentration of 1 mg/L and < 532 at a concentration of 0.1 mg/L. Due to the structural similarity of the main metabolite of CAS 36443-68-2 similar results can be expected. The BCF of the metabolite of CAS 36443-68-2 3-(3-tert-butyl-4-hydroxy-5-methyl-phenyl)propanoic acid is expected to be clearly below the B threshold of 2000.

In summary, due to the experimental and predicted BCF values and the logD of << 4.5 the substance is expected to be significantly below the B threshold of 2000.

 

Assessment for the metabolite No. 31 of CAS 36443-68-2

The metabolite No. 31 of was predicted to occur with 0.38 % and was further assessed for its bioaccumulation potential with the EPI Suite 4.11 BCFBAF 3.01 model. A BCF of 1.234 L/Kg was predicted for the mid trophic level and taking biotransformation processes into account. The metabolite was within the applicability domain of the submodel  BCFBAF Arnot & Gobas and can be considered reliable.

 

Conclusion

In order to this, neither the parent substance nor the relevant predicted metabolites are expected to bioaccumulate in organisms.