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Bioaccumulation: aquatic / sediment

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Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
(Q)SAR
Adequacy of study:
key study
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:
For the QMRF, see 'Overall remarks, attachments'.
For the QPRF, see 'Executive summary'.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Calculation using BCFBAF (v3.01)
GLP compliance:
no
Specific details on test material used for the study:
- Substance name (as in EPISuite CAS inventory): 1-Tridecanol
- SMILES: CCCCCCCCCCCCCO
Details on estimation of bioconcentration:
BASIS FOR CALCULATION OF BCF
- Estimation software: EPISuite-BCFBAF (version 3.01)
- Result based on calculated log Pow of: 5.26
Type:
BCF
Value:
11 740 L/kg
Basis:
whole body w.w.
Remarks on result:
other: Arnot-Gobas estimated log BCF (upper trophic) assuming a biotransformation rate of zero.
Type:
BCF
Value:
470 L/kg
Remarks on result:
other: Arnot-Gobas estimated log BCF (upper trophic) including biotransformation rate estimates.
Type:
BAF
Value:
282 700 L/kg
Remarks on result:
other: Arnot-Gobas estimated log BAF (upper trophic) assuming a biotransformation rate of zero.
Type:
BAF
Value:
475 L/kg
Remarks on result:
other: Arnot-Gobas estimated log BAF (upper trophic) including biotransformation rate estimates.

Summary Results:

Log BCF (regression-based estimate): 1.76 (BCF = 58.1 L/kg wet-wt)

Biotransformation Half-Life (days): 1.19 (normalized to 10 g fish)

Log BAF (Arnot-Gobas upper trophic): 2.68 (BAF = 476 L/kg wet-wt)

 

Log Kow (experimental): not available from database

Log Kow used by BCF estimates: 5.26

 

Equation Used to Make BCF estimate:

Log BCF = 0.6598 log Kow - 0.333 + Correction

 

Correction(s):                         Value

Alkyl chains (8+ -CH2- groups) -1.374

 

Estimated Log BCF = 1.764 (BCF = 58.06 L/kg wet-wt)

 

Whole Body Primary Biotransformation Rate Estimate for Fish:

TYPE

NUM

LOG BIODEGRADATION FRAGMENT DESCRIPTION

COEFF

VALUE

Frag

1

Linear C4 terminal chain [CCC-CH3]

0.0341

0.0341

Frag

1

Aliphatic alcohol [-OH]

-0.0616

-0.0616

Frag

1

Methyl [-CH3]

0.2451

0.2451

Frag

12

-CH2- [linear]

0.0242

0.2902

L Kow

*

Log Kow = 5.26 (KowWin estimate)

0.3073

1.6169

MolWt

*

Molecular Weight Parameter

-0.5138

Const

*

Equation Constant

-1.5371

Result

Log Bio Half-Life (days)

0.0739

Result

Bio Half-life (days)

1.186

Note: Bio Half-Life normalized to 10g fish at 15 °C

 

Biotransformation Rate Constant:

kM (Rate Constant): 0.5846 /day (10 gram fish)

kM (Rate Constant): 0.3288 /day (100 gram fish)

kM (Rate Constant): 0.1849 /day (1 kg fish)

kM (Rate Constant): 0.104 /day (10 kg fish)

 

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

Estimated Log BCF (upper trophic) = 2.672 (BCF = 469.5 L/kg wet-wt)

Estimated Log BAF (upper trophic) = 2.677 (BAF = 475.8 L/kg wet-wt)

Estimated Log BCF (mid trophic) = 2.798 (BCF = 628.4 L/kg wet-wt)

Estimated Log BAF (mid trophic) = 2.856 (BAF = 718.6 L/kg wet-wt)

Estimated Log BCF (lower trophic) = 2.835 (BCF = 683.9 L/kg wet-wt)

Estimated Log BAF (lower trophic) = 3.031 (BAF = 1074 L/kg wet-wt)

 

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

Estimated Log BCF (upper trophic) = 4.070 (BCF = 1.174e+004 L/kg wet-wt)

Estimated Log BAF (upper trophic) = 5.451 (BAF = 2.827e+005 L/kg wet-wt)

Executive summary:

QPRF: BCFBAF v3.01 

1.

Substance

See “Test material identity”

2.

General information

 

2.1

Date of QPRF

See “Data Source (Reference)”

2.2

QPRF author and contact details

See “Data Source (Reference)”

3.

Prediction

3.1

Endpoint
(OECD Principle 1)

Endpoint

Bioaccumulation (aquatic)

Dependent variable

- Bioconcentration factor (BCF)

- Bioaccumulation factor (BAF; 15 °C)

- Biotransformation rate (kM) and half-life

3.2

Algorithm
(OECD Principle 2)

Model or submodel name

BCFBAF

Submodels:

1) Bioconcentration factor (BCF; Meylan et al., 1997/1999)

2) Biotransformation rate in fish (kM; Arnot et al., 2008a/b)

3) Arnot & Gobas BAF and steady-state BCF Arnot & Gobas, 2003)

Model version

v. 3.01

Reference to QMRF

Estimation of Bioconcentration, bioaccumulation and biotransformation in fish using BCFBAF v3.01 (EPI Suite v4.11)

Predicted value (model result)

See “Results and discussion”

Input for prediction

Chemical structure via CAS number or SMILES; log Kow (optional)

Descriptor values

- SMILES: structure of the compound as SMILES notation

- log Kow

- Molecular weight

3.3

Applicability domain
(OECD principle 3)

Domains:

1) Bioconcentration factor (BCF; Meylan et al., 1997/1999)

a) Ionic/non-Ionic

The substance is non-ionic.

b) Molecular weight (range of test data set):

- Ionic: 68.08 to 991.80

- Non-ionic: 68.08 to 959.17

(On-Line BCFBAF Help File, Ch. 7.1.3 Estimation Domain and Appendix G)

The substance is within range (200.4 g/mol).

c) log Kow (range of test data set):

- Ionic: -6.50 to 11.26

- Non-ionic: -1.37 to 11.26

(On-Line BCFBAF Help File, Ch. 7.1.3 Estimation Domain and Appendix G)

The substance is within range (5.26).

 

d) Maximum number of instances of correction factor in any of the training set compounds (On-Line BCFBAF Help File, Appendix E)

Not exceeded.

2) Biotransformation rate in fish (kM; Arnot et al., 2008a/b)

a) The substance does not appreciably ionize at physiological pH.

(On-Line BCFBAF Help File, Ch. 7.2.3)

Fulfilled

b) Molecular weight (range of test data set): 68.08 to 959.17

(On-Line BCFBAF Help File, Ch. 7.2.3)

The substance is within range (200.4 g/mol).

c) The molecular weight is ≤ 600 g/mol.

(On-Line BCFBAF Help File, Ch. 7.2.3)

Fulfilled

d) Log Kow: 0.31 to 8.70

(On-Line BCFBAF Help File, Ch. 7.2.3)

The substance is within range (5.26).

e) The substance is no metal or organometal, pigment or dye, or a perfluorinated substance.

(On-Line BCFBAF Help File, Ch. 7.2.3)

Fulfilled

f) Maximum number of instances of biotransformation fragments in any of the training set compounds (On-Line BCFBAF Help File, Appendix F)

Not exceeded.

3) Arnot & Gobas BAF and steady-state BCF Arnot & Gobas, 2003)

a) Log Kow ≤ 9

(On-Line BCFBAF Help File, Ch. 7.3.1)

Fulfilled

b) The substance does not appreciably ionize.

(On-Line BCFBAF Help File, Ch. 7.3.1)

Fulfilled

c) The substance is no pigment, dye, or perfluorinated substance.

(On-Line BCFBAF Help File, Ch. 7.3.1)

Fulfilled

3.4

The uncertainty of the prediction
(OECD principle 4)

1. Bioconcentration factor (BCF; Meylan et al., 1997/1999)

Statistical accuracy of the training data set (non-ionic plus ionic data):

- Correlation coefficient (r2) = 0.833

- Standard deviation = 0.502 log units

- Absolute mean error = 0.382 log units

 

2. Biotransformation Rate in Fish (kM)

Statistical accuracy (training set):

- Correlation coefficient (r2) = 0.821

- Correlation coefficient (Q2) = 0.753

- Standard deviation = 0.494 log units

- Absolute mean error = 0.383 log units

 

3. Arnot-Gobas BAF/BCF model

No information on the statistical accuracy given in the documentation.

3.5

The chemical mechanisms according to the model underpinning the predicted result
(OECD principle 5)

1. The BCF model is mainly based on the relationship between bioconcentration and hydrophobicity. The model also takes into account the chemical structure and the ionic/non-ionic character of the substance.

 

2. Bioaccumulation is the net result of relative rates of chemical inputs to an organism from multimedia exposures (e.g., air, food, and water) and chemical outputs (or elimination) from the organism.

 

3. The model includes mechanistic processes for bioconcentration and bioaccumulation such as chemical uptake from the water at the gill surface (BCFs and BAFs) and the diet (BAFs only), and chemical elimination at the gill surface, fecal egestion, growth dilution and metabolic biotransformation (Arnot and Gobas 2003). Other processes included in the calculations are bioavailability in the water column (only the freely dissolved fraction can bioconcentrate) and absorption efficiencies at the gill and in the gastrointestinal tract.

References

- Arnot JA, Gobas FAPC. 2003. A generic QSAR for assessing the bioaccumulation potential of organic chemicals in aquatic food webs. QSAR and Combinatorial Science 22: 337-345.

- Arnot JA, Mackay D, Parkerton TF, Bonnell M. 2008a. A database of fish biotransformation rates for organic chemicals. Environmental Toxicology and Chemistry 27(11), 2263-2270.

- Arnot JA, Mackay D, Bonnell M. 2008b. Estimating metabolic biotransformation rates in fish from laboratory data. Environmental Toxicology and Chemistry 27: 341-351.

- Meylan, W.M., Howard, P.H, Aronson, D., Printup, H. and S. Gouchie. 1997. "Improved Method for Estimating Bioconcentration Factor (BCF) from Octanol-Water Partition Coefficient", SRC TR-97-006 (2nd Update), July 22, 1997; prepared for: Robert S. Boethling, EPA-OPPT, Washington, DC; Contract No. 68-D5-0012; prepared by: ; Syracuse Research Corp., Environmental Science Center, 6225 Running Ridge Road, North Syracuse, NY 13212.

- Meylan, WM, Howard, PH, Boethling, RS et al. 1999. Improved Method for Estimating Bioconcentration / Bioaccumulation Factor from Octanol/Water Partition Coefficient. Environ. Toxicol. Chem. 18(4): 664-672 (1999). 

- US EPA (2012). On-Line BCFBAF Help File. .

Identified Correction Factors (Appendix E)

Correction Factors: Not used for Log Kow < 1.

 

Biotransformation Fragments and Coefficient values (Appendix F)

Fragment Description

Coefficient value

No. compounds containing fragment in total training set

Maximum number of each fragment in any individual compound

No. of instances of each fragment for the current substance

Linear C4 terminal chain [CCC-CH3]        

0.03412373

43

3

1

Aliphatic alcohol [-OH]                    

-0.06155701

7

3

1

Methyl [-CH3]                              

0.24510529

170

12

1

-CH2- [linear]                            

0.02418707

109

28

12

 

Assessment of Applicability Domain Based on Molecular Weight and log Kow

 

1. Bioconcentration Factor (BCF; Meylan et al., 1997/1999)                             

Training set: Molecular weights

Ionic

Non-ionic

Minimum

68,08

68,08

Maximum

991,80

959,17

Average

244,00

244,00

Assessment of molecular weight

Molecular weight within range of training set

Training set: Log Kow

Ionic

Non-ionic

Minimum

-6,50

-1,37

Maximum

11,26

11,26

Assessment of log Kow

Log Kow within range of training set.

 

2. Biotransformation Rate in Fish (kM; Arnot et al., 2008a/b)                            

Training set: Molecular weights

Minimum

68,08

Maximum

959,17

Average

259,75

Assessment of molecular weight

Molecular weight within range of training set

Training set: Log Kow

Minimum

0,31

Maximum

8,70

Assessment of log Kow

Log Kow within range of training set.

                                  

3. Arnot-Gobas BAF/BCF (Arnot & Gobas, 2003)

Assessment of log Kow: Log Kow within acceptable range (log Kow ≤ 9).

Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
(Q)SAR
Adequacy of study:
key study
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:
For the QMRF, see 'Overall remarks, attachments'.
For the QPRF, see 'Executive summary'.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Calculation using BCFBAF (v3.01)
GLP compliance:
no
Specific details on test material used for the study:
- Substance name (as in EPISuite CAS inventory): 1-Pentadecanol
- SMILES: CCCCCCCCCCCCCCCO
Details on estimation of bioconcentration:
BASIS FOR CALCULATION OF BCF
- Estimation software: EPISuite-BCFBAF (version 3.01)
- Result based on calculated log Pow of: 6.24
Type:
BCF
Value:
20 720 L/kg
Basis:
whole body w.w.
Remarks on result:
other: Arnot-Gobas estimated log BCF (upper trophic) assuming a biotransformation rate of zero.
Type:
BCF
Value:
678 L/kg
Basis:
whole body w.w.
Remarks on result:
other: Arnot-Gobas estimated log BCF (upper trophic) including biotransformation rate estimates.
Type:
BAF
Value:
4 435 000 L/kg
Basis:
whole body w.w.
Remarks on result:
other: Arnot-Gobas estimated log BAF (upper trophic) assuming a biotransformation rate of zero.
Type:
BAF
Value:
971 L/kg
Basis:
whole body w.w.
Remarks on result:
other: Arnot-Gobas estimated log BAF (upper trophic) including biotransformation rate estimates.

Summary Results:

Log BCF (regression-based estimate): 2.41 (BCF = 258 L/kg wet-wt)

Biotransformation Half-Life (days): 2.25 (normalized to 10 g fish)

Log BAF (Arnot-Gobas upper trophic): 2.99 (BAF = 971 L/kg wet-wt)

 

Log Kow (experimental): not available from database

Log Kow used by BCF estimates: 6.24

 

Equation Used to Make BCF estimate:

Log BCF = 0.6598 log Kow - 0.333 + Correction

 

Correction(s):                          Value

Alkyl chains (8+ -CH2- groups)  -1.374

 

Estimated Log BCF = 2.412 (BCF = 258.2 L/kg wet-wt)

 

Whole Body Primary Biotransformation Rate Estimate for Fish:

TYPE

NUM

LOG BIODEGRADATION FRAGMENT DESCRIPTION

COEFF

VALUE

Frag

1

Linear C4 terminal chain [CCC-CH3]

0.0341

0.0341

Frag

1

Aliphatic alcohol [-OH]

-0.0616

-0.0616

Frag

1

Methyl [-CH3]

0.2451

0.2451

Frag

14

-CH2- [linear]

0.0242

0.3386

L Kow

*

Log Kow = 6.24 (KowWin estimate)

0.3073

1.9188

MolWt

*

Molecular Weight Parameter

-0.5857

Const

*

Equation Constant

-1.5371

Result

Log Bio Half-Life (days)

0.3522

Result

Bio Half-life (days)

2.25

Note: Bio Half-Life normalized to 10g fish at 15 °C

 

Biotransformation Rate Constant:

kM (Rate Constant): 0.308 /day (10 gram fish)

kM (Rate Constant): 0.1732 /day (100 gram fish)

kM (Rate Constant): 0.09741 /day (1 kg fish)

kM (Rate Constant): 0.05478 /day (10 kg fish)

 

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

Estimated Log BCF (upper trophic) = 2.831 (BCF = 677.8 L/kg wet-wt)

Estimated Log BAF (upper trophic) = 2.987 (BAF = 970.7 L/kg wet-wt)

Estimated Log BCF (mid trophic) = 2.969 (BCF = 930.2 L/kg wet-wt)

Estimated Log BAF (mid trophic) = 3.508 (BAF = 3224 L/kg wet-wt)

Estimated Log BCF (lower trophic) = 3.010 (BCF = 1024 L/kg wet-wt)

Estimated Log BAF (lower trophic) = 3.921 (BAF = 8332 L/kg wet-wt)

 

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

Estimated Log BCF (upper trophic) = 4.316 (BCF = 2.072e+004 L/kg wet-wt)

Estimated Log BAF (upper trophic) = 6.647 (BAF = 4.435e+006 L/kg wet-wt)

Executive summary:

QPRF: BCFBAF v3.01 

1.

Substance

See “Test material identity”

2.

General information

 

2.1

Date of QPRF

See “Data Source (Reference)”

2.2

QPRF author and contact details

See “Data Source (Reference)”

3.

Prediction

3.1

Endpoint
(OECD Principle 1)

Endpoint

Bioaccumulation (aquatic)

Dependent variable

- Bioconcentration factor (BCF)

- Bioaccumulation factor (BAF; 15 °C)

- Biotransformation rate (kM) and half-life

3.2

Algorithm
(OECD Principle 2)

Model or submodel name

BCFBAF

Submodels:

1) Bioconcentration factor (BCF; Meylan et al., 1997/1999)

2) Biotransformation rate in fish (kM; Arnot et al., 2008a/b)

3) Arnot & Gobas BAF and steady-state BCF Arnot & Gobas, 2003)

Model version

v. 3.01

Reference to QMRF

Estimation of Bioconcentration, bioaccumulation and biotransformation in fish using BCFBAF v3.01 (EPI Suite v4.11)

Predicted value (model result)

See “Results and discussion”

Input for prediction

Chemical structure via CAS number or SMILES; log Kow (optional)

Descriptor values

- SMILES: structure of the compound as SMILES notation

- log Kow

- Molecular weight

3.3

Applicability domain
(OECD principle 3)

Domains:

1) Bioconcentration factor (BCF; Meylan et al., 1997/1999)

a) Ionic/non-Ionic

The substance is non-ionic.

b) Molecular weight (range of test data set):

- Ionic: 68.08 to 991.80

- Non-ionic: 68.08 to 959.17

(On-Line BCFBAF Help File, Ch. 7.1.3 Estimation Domain and Appendix G)

The substance is within range (228.4 g/mol).

c) log Kow (range of test data set):

- Ionic: -6.50 to 11.26

- Non-ionic: -1.37 to 11.26

(On-Line BCFBAF Help File, Ch. 7.1.3 Estimation Domain and Appendix G)

The substance is within range (6.24).

 

d) Maximum number of instances of correction factor in any of the training set compounds (On-Line BCFBAF Help File, Appendix E)

Not exceeded.

2) Biotransformation rate in fish (kM; Arnot et al., 2008a/b)

a) The substance does not appreciably ionize at physiological pH.

(On-Line BCFBAF Help File, Ch. 7.2.3)

Fulfilled

b) Molecular weight (range of test data set): 68.08 to 959.17

(On-Line BCFBAF Help File, Ch. 7.2.3)

The substance is within range (228.4 g/mol).

c) The molecular weight is ≤ 600 g/mol.

(On-Line BCFBAF Help File, Ch. 7.2.3)

Fulfilled

d) Log Kow: 0.31 to 8.70

(On-Line BCFBAF Help File, Ch. 7.2.3)

The substance is within range (6.24).

e) The substance is no metal or organometal, pigment or dye, or a perfluorinated substance.

(On-Line BCFBAF Help File, Ch. 7.2.3)

Fulfilled

f) Maximum number of instances of biotransformation fragments in any of the training set compounds (On-Line BCFBAF Help File, Appendix F)

Not exceeded.

3) Arnot & Gobas BAF and steady-state BCF Arnot & Gobas, 2003)

a) Log Kow ≤ 9

(On-Line BCFBAF Help File, Ch. 7.3.1)

Fulfilled

b) The substance does not appreciably ionize.

(On-Line BCFBAF Help File, Ch. 7.3.1)

Fulfilled

c) The substance is no pigment, dye, or perfluorinated substance.

(On-Line BCFBAF Help File, Ch. 7.3.1)

Fulfilled

3.4

The uncertainty of the prediction
(OECD principle 4)

1. Bioconcentration factor (BCF; Meylan et al., 1997/1999)

Statistical accuracy of the training data set (non-ionic plus ionic data):

- Correlation coefficient (r2) = 0.833

- Standard deviation = 0.502 log units

- Absolute mean error = 0.382 log units

 

2. Biotransformation Rate in Fish (kM)

Statistical accuracy (training set):

- Correlation coefficient (r2) = 0.821

- Correlation coefficient (Q2) = 0.753

- Standard deviation = 0.494 log units

- Absolute mean error = 0.383 log units

 

3. Arnot-Gobas BAF/BCF model

No information on the statistical accuracy given in the documentation.

3.5

The chemical mechanisms according to the model underpinning the predicted result
(OECD principle 5)

1. The BCF model is mainly based on the relationship between bioconcentration and hydrophobicity. The model also takes into account the chemical structure and the ionic/non-ionic character of the substance.

 

2. Bioaccumulation is the net result of relative rates of chemical inputs to an organism from multimedia exposures (e.g., air, food, and water) and chemical outputs (or elimination) from the organism.

 

3. The model includes mechanistic processes for bioconcentration and bioaccumulation such as chemical uptake from the water at the gill surface (BCFs and BAFs) and the diet (BAFs only), and chemical elimination at the gill surface, fecal egestion, growth dilution and metabolic biotransformation (Arnot and Gobas 2003). Other processes included in the calculations are bioavailability in the water column (only the freely dissolved fraction can bioconcentrate) and absorption efficiencies at the gill and in the gastrointestinal tract.

References

- Arnot JA, Gobas FAPC. 2003. A generic QSAR for assessing the bioaccumulation potential of organic chemicals in aquatic food webs. QSAR and Combinatorial Science 22: 337-345.

- Arnot JA, Mackay D, Parkerton TF, Bonnell M. 2008a. A database of fish biotransformation rates for organic chemicals. Environmental Toxicology and Chemistry 27(11), 2263-2270.

- Arnot JA, Mackay D, Bonnell M. 2008b. Estimating metabolic biotransformation rates in fish from laboratory data. Environmental Toxicology and Chemistry 27: 341-351.

- Meylan, W.M., Howard, P.H, Aronson, D., Printup, H. and S. Gouchie. 1997. "Improved Method for Estimating Bioconcentration Factor (BCF) from Octanol-Water Partition Coefficient", SRC TR-97-006 (2nd Update), July 22, 1997; prepared for: Robert S. Boethling, EPA-OPPT, Washington, DC; Contract No. 68-D5-0012; prepared by: ; Syracuse Research Corp., Environmental Science Center, 6225 Running Ridge Road, North Syracuse, NY 13212.

- Meylan, WM, Howard, PH, Boethling, RS et al. 1999. Improved Method for Estimating Bioconcentration / Bioaccumulation Factor from Octanol/Water Partition Coefficient. Environ. Toxicol. Chem. 18(4): 664-672 (1999). 

- US EPA (2012). On-Line BCFBAF Help File. .

Identified Correction Factors (Appendix E)

Correction Factors: Not used for Log Kow < 1.

 

Biotransformation Fragments and Coefficient values (Appendix F)

 

Fragment Description

Coefficient value

No. compounds containing fragment in total training set

Maximum number of each fragment in any individual compound

No. of instances of each fragment for the current substance

Linear C4 terminal chain [CCC-CH3]        

0.03412373

43

3

1

Aliphatic alcohol [-OH]                    

-0.06155701

7

3

1

Methyl [-CH3]                              

0.24510529

170

12

1

-CH2- [linear]                            

0.02418707

109

28

14

 

Assessment of Applicability Domain Based on Molecular Weight and log Kow

 

1. Bioconcentration Factor (BCF; Meylan et al., 1997/1999)                             

Training set: Molecular weights

Ionic

Non-ionic

Minimum

68,08

68,08

Maximum

991,80

959,17

Average

244,00

244,00

Assessment of molecular weight

Molecular weight within range of training set

Training set: Log Kow

Ionic

Non-ionic

Minimum

-6,50

-1,37

Maximum

11,26

11,26

Assessment of log Kow

Log Kow within range of training set.

 

2. Biotransformation Rate in Fish (kM; Arnot et al., 2008a/b)                            

Training set: Molecular weights

Minimum

68,08

Maximum

959,17

Average

259,75

Assessment of molecular weight

Molecular weight within range of training set

Training set: Log Kow

Minimum

0,31

Maximum

8,70

Assessment of log Kow

Log Kow within range of training set.

                                  

3. Arnot-Gobas BAF/BCF (Arnot & Gobas, 2003)

Assessment of log Kow: Log Kow within acceptable range (log Kow ≤ 9).

Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
See the OECD SIDS (2006) category approach under IUCLID section 13: 'Assessment reports'.
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Test organisms (species):
other: fish
Key result
Type:
BCF
Value:
>= 470 - <= 678 L/kg
Basis:
whole body w.w.
Remarks on result:
other: as determined from read-across to C13 alcohol, linear (lower value) and C15 alcohol, linear (higher value).
Type:
BAF
Value:
>= 476 - <= 971 L/kg
Basis:
whole body w.w.
Remarks on result:
other: as determined from read-across to C13 alcohol, linear (lower value) and C15 alcohol, linear (higher value).
Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Peer reviewed data
Qualifier:
according to
Guideline:
OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)
GLP compliance:
not specified
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
TEST ORGANISM
- Common name: rainbow trout
- Age at study initiation: juvenile
- Weight at study initiation: 0.2 - 0.9 g
- Lipid content: 3.5 - 5.8%

Route of exposure:
aqueous
Test type:
flow-through
Water / sediment media type:
natural water: freshwater
Total exposure / uptake duration:
10 d
Total depuration duration:
4 d
Nominal and measured concentrations:
Two test concentrations
Type:
BCF
Value:
< 100 dimensionless
Details on results:
- Uptake phase: fish attained rapidly a steady-state concentration of alcohols
- Rapid elimination occurred after transfer to clean water

Description of key information

C13 -15 -branched and linear has a low potential for bioconcentration in organisms. Calculated BCF values for C13 and C15 linear alcohols are determined at 500 - 1000 L/kg and presents a worst-case assumption. In a GLP-study according to OECD guideline 305, individuals of Oncorhynchus mykiss were exposed to two concentrations of alcohols (C10, C12, C13) for a period of 10 days, following by a depuration period of 4 days. The determined BCF values are < 100 [de Wolf & Parkerton 1999]. This shows that predicted BCF values overestimates the potential for bioconcentration of these kind of alcohols in organisms.

Key value for chemical safety assessment

Additional information

In the OECD SIDS of 2006 bioconcentration factors (BCF) calculated on the basis of log Kow for among others the C13 to C15 chain length linear alcohols range from 349 L/kg for C13 (BCFWIN) to a maximum of ca. 42500 L/kg for C15 (Connell & Hawker, 1988). The presence of branched components is not expected to significantly affect the predicted value. However, for C16 a measured value of 56 and a range of values from 507-1550 from two unreliable studies exist and BCF data for alcohols similar to those in this family but with 2.1-2.9 branches per molecule also indicate that BCF (Q)SAR overestimate BCF. The log Kow-based BCF (Q)SAR predictions used at the time take no account of biotransformation/metabolism of alcohols in living organisms. However, the mammalian metabolism of the aliphatic alcohols is highly efficient and proceeds similarly for each of the sub-categories. The first step of the biotransformation the alcohols are oxidised to the corresponding carboxylic acids, followed by a stepwise elimination of C2 units in the mitochondrial β-oxidation process. The metabolic breakdown of mono-branched alcohol isomers is also highly efficient and involves processes that are identical to that of the linear aliphatic alcohols. The presence of a side chain does not terminate the β-oxidation process, however in some cases a single Carbon unit is removed before the C2 elimination can proceed. Based on this information, and considering that the (Q)SAR used take no account of biotransformation/metabolism of alcohols in living organisms, it is in the OECD SIDS document concluded that it may be expected that the category members will have a low potential for bioaccumulation.

Therefore, Arnot-Gobas predictions, with and without metabolic activation, were performed and compared to provide further inside in the potential for bioaccumulation. For the C13 linear alcohol BCF and BAF values are predicted to be 11740 L/kg and 282700 L/kg, respectively when a biotransformation rate of zero is assumed. These values are comparable to, or rather somewhat higher, than the predicted values in the OECD SIDS document. When however, biotransformation rate estimates are included in the estimation, BCF and BAF values drop significantly to values of 470 L/kg and 475 L/kg, respectively. In the case of the C15 linear alcohol the BCF and BAF values are predicted to be 20720 L/kg and 4435000 L/kg, respectively when a biotransformation rate of zero is assumed and 678 L/kg and 971 L/kg when biotransformation is taken into account.

Altogether, considering the very efficient metabolism of the log chain alcohols, it is considered that the Arnot-Gobas predicted values are still likely to be on the high end of what would be expected. For the substance as a whole, a BCF of ca. 500 - 1000 L/kg is determined which is considered to be reasonable worst case assumption. This assumption is supported by the results of De Wolf and Parkerton (1999). The authors demonstrates in a study with alcohols (C10, C12, C13) that measured BCF values are much lower than the predicted ones. In their study a BCF of < 100 was determined.

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.

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 the substance (Q)SAR results were used for assessment of 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.