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Biodegradation in water and sediment: simulation tests

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Endpoint:
biodegradation in water: sediment simulation testing
Data waiving:
other justification
Justification for data waiving:
the study does not need to be conducted because the substance is readily biodegradable
Transformation products:
no
Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP non-guideline experimental study, published in peer reviewed literature, predates implementation of GLP and/or development of study guidelines but otherwise acceptable for assessment.
Principles of method if other than guideline:
Gas exchange-biodegradation experiments conducted in model estuarine ecosystem.
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Radiolabelling:
no
Oxygen conditions:
aerobic
Inoculum or test system:
natural water
Details on source and properties of surface water:
Model esturaine ecosystem (replicates the gross features of Narrangansett Bay biological community and nutrient levels).
Details on source and properties of sediment:
Model esturaine ecosystem (replicates the gross features of Narrangansett Bay biological community and nutrient levels).
Details on inoculum:
No data reported
Duration of test (contact time):
633 h
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
Gas-exchange-biodegradation experiments were conducted using model estuarine ecosystems comprised of materials from Naragansett Bay. The first experiment was conducted in batch mode at 20°C without the presence of sediments and the second experiment was carried out in flow-through mode at 10°C with an average water exchange rate of 3.7% per day. The losses due to gas exchange in experiment 1 and to gas exchange and water outflow in experiment 2 were compensated for using radon as a conservative marker gas. Radon does not undergo biodegradation and radioactive decay was compensated for in the calculations. Hydrocarbons were introduced to the ecosystem experiment by addition to an inverted container suspended in the water tank, thereby creating a trapped gas pocket. Water was circulated through the gas pocket for about 12 hours using a pump and the container was then removed. A 232radon spike was introduced to the tank by adding 2% tapwater which had about 1000 times the radon content of the Naragansett Bay water. The decrease in concentration with time of the gases was monitored.

In both experiments, samples for hydrocarbon analysis were collected by siphon from 50 cm below the surface of the water; tests had shown that no concentration gradients were present in the water column. The samples were equilibrated at a controlled temperature (22.5°C) with a known volume of headspace in a sealed vial and a sample of the headspace was analysed using GC-FID. Radon samples were collected by drawing water from a depth of 50cm into pre-evacuated bottles, analysed and the results corrected for blanks, natural backgrounds, ingrowth and decay.
Reference substance:
other: Radon (222Rn) to compensate for outflow and gas exchange
Test performance:
In the study with just marine water, isobutane showed evidence of degradation with half-times of 16 to 26 days. Samples from later in the experiment showed much more rapid biodegradation, which the authors interpret as resulting from adjustment of the bacterial populations to the availability of the substances.
In the study with marine water and sediment, isobutane showed evidence of degradation from test initiation, with half-lives of 33 to 139 days. The slower rates of degradation compared to experiment 1 are thought to result from the lower temperature (10°C as opposed to 20°C). A lag-time of approximately 2 weeks was seen for the bacteria in the tank to respond completely to the availability of the gases and develop a population with a strong hydrocarbon utilisation capability. Between 311 and 400 hours, isobtane showed rapid decreases in concentration, far in excess of earlier degradation, gas exchange and outflow.
Compartment:
natural water: marine
DT50:
16 - 26 d
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Compartment:
other: Marine water and sediment model
DT50:
33 - 139 d
Type:
(pseudo-)first order (= half-life)
Temp.:
10 °C
Transformation products:
not specified
Details on transformation products:
No data reported
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
Residues:
not specified
Details on results:
Experiment 1
Observed rate constant in days-1 (± 1 SD): 0.061 ± 0.005
Rate constant in days-1 predicted for gas exchange at z=560 µM: 0.026
Predicted rate constant for degradation (observed - gas exchange) in days-1 (± 1 SD): 0.035 ± 0.008

Experiment 2
Observed rate constant in days-1 (± 1 SD): 0.030 ± 0.006
Rate constant in days-1 predicted for gas exchange at z=600 µM: 0.017
Predicted rate constant for degradation (observed - gas exchange) in days-1 (± 1 SD): 0.013 ± 0.008
Results with reference substance:
Radon (222Rn) is a non-degradable gas used to compensate for outflow and gas exchange
Validity criteria fulfilled:
not applicable
Remarks:
Non-standard method
Conclusions:
The half-life in marine water was reported as 16 to 26 days, while the half-life in the marine water and sediment model was reported as 33 to 139 days.
Executive summary:

Experimental data are available on the persistence of the substances in marine water and marine water and sediment systems (Bopp et al. 1981). The study is a non-GLP, non-guideline study but is well described and is considered reliable and suitable for use for this endpoint. Gas exchange-biodegradation experiments conducted in model estuarine ecosystem shows that members of the category are not expected to be persistent.

In the study with just marine water, isobutane showed evidence of degradation with half-times of 16 to 26 days. Samples from later in the experiment showed much more rapid biodegradation, which the authors interpret as resulting from adjustment of the bacterial populations to the availability of the substances.

In the study with marine water and sediment, isobutane showed slow initial degradation, with a half life of 33 to 139 days. A lag-time of approximately 2 weeks was seen for the bacteria in the tank to respond completely to the availability of the gases and develop a population with a strong hydrocarbon utilisation capability. Between 311 and 400 hours, isobuane showed rapid decreases in concentration, far in excess of earlier degradation, gas exchange and outflow and was degraded completely within about 3 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP non-guideline experimental study, published in peer reviewed literature, predates implementation of GLP and/or development of study guidelines but otherwise acceptable for assessment.
Principles of method if other than guideline:
Gas exchange-biodegradation experiments conducted in model estuarine ecosystem.
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Radiolabelling:
no
Oxygen conditions:
aerobic
Inoculum or test system:
natural water
Details on source and properties of surface water:
Model esturaine ecosystem (replicates the gross features of Narrangansett Bay biological community and nutrient levels).
Details on source and properties of sediment:
Model esturaine ecosystem (replicates the gross features of Narrangansett Bay biological community and nutrient levels).
Details on inoculum:
No data reported
Duration of test (contact time):
633 h
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
Gas-exchange-biodegradation experiments were conducted using model estuarine ecosystems comprised of materials from Naragansett Bay. The first experiment was conducted in batch mode at 20°C without the presence of sediments and the second experiment was carried out in flow-through mode at 10°C with an average water exchange rate of 3.7% per day. The losses due to gas exchange in experiment 1 and to gas exchange and water outflow in experiment 2 were compensated for using radon as a conservative marker gas. Radon does not undergo biodegradation and radioactive decay was compensated for in the calculations. Hydrocarbons were introduced to the ecosystem experiment by addition to an inverted container suspended in the water tank, thereby creating a trapped gas pocket. Water was circulated through the gas pocket for about 12 hours using a pump and the container was then removed. A 232radon spike was introduced to the tank by adding 2% tapwater which had about 1000 times the radon content of the Naragansett Bay water. The decrease in concentration with time of the gases was monitored.

In both experiments, samples for hydrocarbon analysis were collected by siphon from 50 cm below the surface of the water; tests had shown that no concentration gradients were present in the water column. The samples were equilibrated at a controlled temperature (22.5°C) with a known volume of headspace in a sealed vial and a sample of the headspace was analysed using GC-FID. Radon samples were collected by drawing water from a depth of 50cm into pre-evacuated bottles, analysed and the results corrected for blanks, natural backgrounds, ingrowth and decay.
Reference substance:
other: Radon (222Rn) to compensate for outflow and gas exchange
Test performance:
In the study with marine water and sediment, butane showed evidence of degradation from test initiation, with half-lives of 18 to 29 days. A lag-time of approximately 2 weeks was seen for the bacteria in the tank to respond completely to the availability of the gases and develop a population with a strong hydrocarbon utilisation capability. Between 311 and 400 hours, butane showed rapid decreases in concentration, far in excess of earlier degradation, gas exchange and outflow.
Compartment:
other: Marine water and sediment model
DT50:
18 - 29 d
Type:
(pseudo-)first order (= half-life)
Temp.:
10 °C
Transformation products:
not specified
Details on transformation products:
No data reported
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
Residues:
not specified
Details on results:
Experiment 2
Observed rate constant in days-1 (± 1 SD): 0.049 ± 0.005
Rate constant in days-1 predicted for gas exchange at z=600 µM: 0.018
Predicted rate constant for degradation (observed - gas exchange) in days-1 (± 1 SD): 0.031 ± 0.007
Results with reference substance:
Radon (222Rn) is a non-degradable gas used to compensate for outflow and gas exchange
Validity criteria fulfilled:
not applicable
Remarks:
Non-standard method
Conclusions:
The half-life in the half-life in the marine water and sediment model was reported as 18 to 29 days.
Executive summary:

Experimental data are available on the persistence of the substances in marine water and sediment systems (Bopp et al. 1981). The study is a non-GLP, non-guideline study but is well described and is considered reliable and suitable for use for this endpoint. Gas exchange-biodegradation experiments conducted in model estuarine ecosystem shows that members of the category are not expected to be persistent.

In the study with marine water and sediment, butane showed slow initial degradation, with a half life of 18 to 29 days. A lag-time of approximately 2 weeks was seen for the bacteria in the tank to respond completely to the availability of the gases and develop a population with a strong hydrocarbon utilisation capability. Between 311 and 400 hours, butane showed rapid decreases in concentration, far in excess of earlier degradation, gas exchange and outflow and was degraded completely within about 3 days.

Experimental data are available on the persistence of the substances in marine water and marine water and sediment systems (Bopp et al. 1981). The study is a non-GLP, non-guideline study but is well described and is considered reliable and suitable for use for this endpoint. Gas exchange-biodegradation experiments conducted in model estuarine ecosystem shows that members of the category are not expected to be persistent.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP non-guideline experimental study, published in peer reviewed literature, predates implementation of GLP and/or development of study guidelines but otherwise acceptable for assessment.
Principles of method if other than guideline:
Gas exchange-biodegradation experiments conducted in model estuarine ecosystem.
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Radiolabelling:
no
Oxygen conditions:
aerobic
Inoculum or test system:
natural water
Details on source and properties of surface water:
Model esturaine ecosystem (replicates the gross features of Narrangansett Bay biological community and nutrient levels).
Details on source and properties of sediment:
Model esturaine ecosystem (replicates the gross features of Narrangansett Bay biological community and nutrient levels).
Details on inoculum:
No data reported
Duration of test (contact time):
633 h
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
Gas-exchange-biodegradation experiments were conducted using model estuarine ecosystems comprised of materials from Naragansett Bay. The first experiment was conducted in batch mode at 20°C without the presence of sediments and the second experiment was carried out in flow-through mode at 10°C with an average water exchange rate of 3.7% per day. The losses due to gas exchange in experiment 1 and to gas exchange and water outflow in experiment 2 were compensated for using radon as a conservative marker gas. Radon does not undergo biodegradation and radioactive decay was compensated for in the calculations. Hydrocarbons were introduced to the ecosystem experiment by addition to an inverted container suspended in the water tank, thereby creating a trapped gas pocket. Water was circulated through the gas pocket for about 12 hours using a pump and the container was then removed. A 232radon spike was introduced to the tank by adding 2% tapwater which had about 1000 times the radon content of the Naragansett Bay water. The decrease in concentration with time of the gases was monitored.

In both experiments, samples for hydrocarbon analysis were collected by siphon from 50 cm below the surface of the water; tests had shown that no concentration gradients were present in the water column. The samples were equilibrated at a controlled temperature (22.5°C) with a known volume of headspace in a sealed vial and a sample of the headspace was analysed using GC-FID. Radon samples were collected by drawing water from a depth of 50cm into pre-evacuated bottles, analysed and the results corrected for blanks, natural backgrounds, ingrowth and decay.
Reference substance:
other: Radon (222Rn) to compensate for outflow and gas exchange
Test performance:
In the study with just marine water, ethane showed evidence of degradation with half-times of 21 to 33 days. Samples from later in the experiment showed much more rapid biodegradation, which the authors interpret as resulting from adjustment of the bacterial populations to the availability of the substances.
In the study with marine water and sediment, a lag-time of approximately 2 weeks was seen for the bacteria in the tank to respond completely to the availability of the gases and develop a population with a strong hydrocarbon utilisation capability. Between 311 and 400 hours, ethane showed rapid decreases in concentration, far in excess of earlier degradation, gas exchange and outflow.
Compartment:
natural water: marine
DT50:
21 - 33 d
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Compartment:
other: Marine water and sediment model
DT50:
>= 87 d
Type:
(pseudo-)first order (= half-life)
Temp.:
10 °C
Transformation products:
not specified
Details on transformation products:
No data reported
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
Residues:
not specified
Details on results:
Experiment 1
Observed rate constant in days-1 (± 1 SD): 0.062 ± 0.003
Rate constant in days-1 predicted for gas exchange at z=560 µM: 0.035
Predicted rate constant for degradation (observed - gas exchange) in days-1 (± 1 SD): 0.027 ± 0.006

Experiment 2
Observed rate constant in days-1 (± 1 SD): 0.027 ± 0.003
Rate constant in days-1 predicted for gas exchange at z=600 µM: 0.024
Predicted rate constant for degradation (observed - gas exchange) in days-1 (± 1 SD): 0.003 ± 0.005
Results with reference substance:
Radon (222Rn) is a non-degradable gas used to compensate for outflow and gas exchange
Validity criteria fulfilled:
not applicable
Remarks:
Non-standard method
Conclusions:
The half-life in marine water was reported as 21 to 33 days, while the half-life in the marine water and sediment model was reported as >=87 days.
Executive summary:

Experimental data are available on the persistence of the substances in marine water and marine water and sediment systems (Bopp et al. 1981). The study is a non-GLP, non-guideline study but is well described and is considered reliable and suitable for use for this endpoint. Gas exchange-biodegradation experiments conducted in model estuarine ecosystem shows that members of the category are not expected to be persistent.

In the study with just marine water, ethane showed evidence of degradation with half-times of 21 to 33 days. Samples from later in the experiment showed much more rapid biodegradation, which the authors interpret as resulting from adjustment of the bacterial populations to the availability of the substances.

In the study with marine water and sediment, ethane showed slow initial degradation, with a half life of >= 87 days. A lag-time of approximately 2 weeks was seen for the bacteria in the tank to respond completely to the availability of the gases and develop a population with a strong hydrocarbon utilisation capability. Between 311 and 400 hours, ethane showed rapid decreases in concentration, far in excess of earlier degradation, gas exchange and outflow and was degraded completely in about 3 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP non-guideline experimental study, published in peer reviewed literature, predates implementation of GLP and/or development of study guidelines but otherwise acceptable for assessment.
Principles of method if other than guideline:
Gas exchange-biodegradation experiments conducted in model estuarine ecosystem.
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Radiolabelling:
no
Oxygen conditions:
aerobic
Inoculum or test system:
natural water
Details on source and properties of surface water:
Model esturaine ecosystem (replicates the gross features of Narrangansett Bay biological community and nutrient levels).
Details on source and properties of sediment:
Model esturaine ecosystem (replicates the gross features of Narrangansett Bay biological community and nutrient levels).
Details on inoculum:
No data reported
Duration of test (contact time):
633 h
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
Gas-exchange-biodegradation experiments were conducted using model estuarine ecosystems comprised of materials from Naragansett Bay. The first experiment was conducted in batch mode at 20°C without the presence of sediments and the second experiment was carried out in flow-through mode at 10°C with an average water exchange rate of 3.7% per day. The losses due to gas exchange in experiment 1 and to gas exchange and water outflow in experiment 2 were compensated for using radon as a conservative marker gas. Radon does not undergo biodegradation and radioactive decay was compensated for in the calculations. Hydrocarbons were introduced to the ecosystem experiment by addition to an inverted container suspended in the water tank, thereby creating a trapped gas pocket. Water was circulated through the gas pocket for about 12 hours using a pump and the container was then removed. A 232radon spike was introduced to the tank by adding 2% tapwater which had about 1000 times the radon content of the Naragansett Bay water. The decrease in concentration with time of the gases was monitored.

In both experiments, samples for hydrocarbon analysis were collected by siphon from 50 cm below the surface of the water; tests had shown that no concentration gradients were present in the water column. The samples were equilibrated at a controlled temperature (22.5°C) with a known volume of headspace in a sealed vial and a sample of the headspace was analysed using GC-FID. Radon samples were collected by drawing water from a depth of 50cm into pre-evacuated bottles, analysed and the results corrected for blanks, natural backgrounds, ingrowth and decay.
Reference substance:
other: Radon (222Rn) to compensate for outflow and gas exchange
Test performance:
In the study with just marine water, propane showed evidence of degradation with half-times of 7 to 9 days. Samples from later in the experiment showed much more rapid biodegradation, which the authors interpret as resulting from adjustment of the bacterial populations to the availability of the substances.
In the study with marine water and sediment, propane showed evidence of degradation from test initiation, with half-lives of 33 to 99 days. The slower rates of degradation compared to experiment 1 are thought to result from the lower temperature (10°C as opposed to 20°C). A lag-time of approximately 2 weeks was seen for the bacteria in the tank to respond completely to the availability of the gases and develop a population with a strong hydrocarbon utilisation capability. Between 311 and 400 hours, propane showed rapid decreases in concentration, far in excess of earlier degradation, gas exchange and outflow.
Compartment:
natural water: marine
DT50:
7 - 9 d
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Compartment:
other: Marine water and sediment model
DT50:
33 - 99 d
Type:
(pseudo-)first order (= half-life)
Temp.:
10 °C
Transformation products:
not specified
Details on transformation products:
No data reported
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
Residues:
not specified
Details on results:
Experiment 1
Observed rate constant in days-1 (± 1 SD): 0.120 ± 0.011
Rate constant in days-1 predicted for gas exchange at z=560 µM: 0.028
Predicted rate constant for degradation (observed - gas exchange) in days-1 (± 1 SD): 0.092 ± 0.014

Experiment 2
Observed rate constant in days-1 (± 1 SD): 0.033 ± 0.005
Rate constant in days-1 predicted for gas exchange at z=600 µM: 0.019
Predicted rate constant for degradation (observed - gas exchange) in days-1 (± 1 SD): 0.014 ± 0.007
Results with reference substance:
Radon (222Rn) is a non-degradable gas used to compensate for outflow and gas exchange
Validity criteria fulfilled:
not applicable
Remarks:
Non-standard method
Conclusions:
The half-life in marine water was reported as 7 to 9 days, while the half-life in the marine water and sediment model was reported as 33 to 99 days.
Executive summary:

Experimental data are available on the persistence of the substances in marine water and marine water and sediment systems (Bopp et al. 1981). The study is a non-GLP, non-guideline study but is well described and is considered reliable and suitable for use for this endpoint. Gas exchange-biodegradation experiments conducted in model estuarine ecosystem shows that members of the category are not expected to be persistent.

In the study with just marine water, propane showed evidence of degradation with half-times of 7 to 9 days. Samples from later in the experiment showed much more rapid biodegradation, which the authors interpret as resulting from adjustment of the bacterial populations to the availability of the substances.

In the study with marine water and sediment, propane showed slow initial degradation, with a half life of 33 to 99 days. A lag-time of approximately 2 weeks was seen for the bacteria in the tank to respond completely to the availability of the gases and develop a population with a strong hydrocarbon utilisation capability. Between 311 and 400 hours, propane showed rapid decreases in concentration, far in excess of earlier degradation, gas exchange and outflow and was degraded completely within about 3 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
4.55 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 4.55 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 4.55 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
2.75 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 2.75 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 2.75 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
1.92 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 1.92 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 1.92 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
2.82 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 2.82 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 2.82 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
3.46 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 3.46 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 3.46 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The BioHCwin half-live of this substance could not be estimated due to the presence of heteroatoms.
Executive summary:

The half-live of this substance could not be estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005) due to the presence of heteroatoms.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
2.55 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 2.55 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 2.55 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
2.91 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 2.91 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 2.91 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
3.19 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 3.19 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 3.19 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
4.03 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 4.03 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 4.03 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
2.36 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 2.36 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 2.36 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
1.92 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 1.92 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 1.92 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
2.97 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 2.97 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 2.97 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
3.09 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 3.09 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 3.09 days.

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
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:
Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Principles of method if other than guideline:
BioHCwin v1.01 in EPISuite 4.1 (2017). The BioHCwin program was developed specifically for the biodegradation half-life prediction of petroleum hydrocarbons. Primary biodegradation half-lives for individual petroleum hydrocarbons are estimated using multiple linear regression against distinct molecular fragments, using a similar approach to several other biodegradation models such as those within the Biodegradation Probability Program (BIOWIN).

BioHCWin training sets were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches. A single recommended biodegradation half-life was chosen for use in the regression analysis from the primary biodegradation data that were compiled for each hydrocarbon structure. Biodegradation data for the xylene isomers and several PAHs were taken from the Syracuse Research Corporation database.
GLP compliance:
no
Oxygen conditions:
aerobic
Based on:
other: QSAR calculation
Parameter followed for biodegradation estimation:
other: QSAR calculation
Details on study design:
Not applicable
DT50:
1.92 d
Type:
not specified
Remarks on result:
other: Result from QSAR prediction
Transformation products:
not measured
Remarks:
QSAR Calculation
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated BioHCwin half-live of this substance is 1.92 days.
Executive summary:

The half-live of this substance has been estimated using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The estimated BioHCwin half-live of this substance is 1.92 days.

Description of key information

There is experimental data from a non-GLP non-guideline experimental study (Bopp, 1981). In just marine water, ethane, propane and 2 -methylpropane (isobutane), showed evidence of degradation with half-lives of 7 to 33 days. In marine water and sediment, propane, butane and isobutane showed evidence of degradation from test initiation, with half-lives of 18 to 139 days but, after a lag-phase of approximately 2 weeks, the substances were degraded completely within about 3 days.


 


It is not feasible to perform simulation tests on complex, volatile UVCBs, especially for a gas category at standard temperature and pressure, the use of the BioHCwin QSAR to predict the biodegradability of this Category is an appropriate technique for this endpoint. Tthe BioHCwin QSAR model of all the constituents in the category indicates that they are expected to have a half-life of 1.92 - 4.55 days. One constituents presented heteroatoms and their BioHCwin half-lives could not be estimated. Of the 15 constituents, no one has a half life of greater than 40 days.


 


 


 

Key value for chemical safety assessment

Additional information

Experimental data

Experimental data are available on the persistence of the substances in marine water and marine water and sediment systems. Gas exchange-biodegradation experiments conducted in model estuarine ecosystem shows that members of the category are not expected to be persistent. The study is a non-GLP, non-guideline study but is well described and is considered suitable for use for this endpoint.

In the study with just marine water, ethane, propane and isobutane showed evidence of degradation with half-times of 7 to 33 days. Samples from later in the experiment showed much more rapid biodegradation, which the authors interpret as resulting from adjustment of the bacterial populations to the availability of the substances. Although results of >70 days were given for the half-life of methane in marine water, the authors report that the loss of methane could be accounted for by gas exchange. Therefore, results for methane have not been included in the REACH dossier as they do not represent actual degradation of the substance.

In the study with marine water and sediment, propane, butane and isobutane showed evidence of degradation from test initiation, with half-lives of 18 to 139 days. The slower rates of degradation compared to experiment 1 are thought to result from the lower temperature (10°C as opposed to 20°C). A lag-time of approximately 2 weeks was seen for the bacteria in the tank to respond completely to the availability of the gases and develop a population with a strong hydrocarbon utilisation capability. Between 311 and 400 hours, ethane, propane, butane and isobutane showed rapid decreases in concentration, far in excess of earlier degradation, gas exchange and outflow. Ethane, which was degraded completely in about 3 days, was the slowest of the substances. Methane also appeared to be degraded during this period, at a rate of about 2.9% per day, corresponding to a half-life of about 24 days.

Ethane, propane, butane and isobutane are subject to degradation in marine ecosystems on the timescale of a few days to a few weeks. Initial rates of degradation are significantly slower than the predicted loss by gas exchange from typical natural estuaries. After a period of 15 to 30 days of moderate degradation, bacterial populations can adjust and degrade gaseous hydrocarbons at least an order to magnitude more rapidly. Thus, for chronic inputs to estuaries, degradation could become the dominant removal mechanism.

QSAR data

Tthe BioHCwin QSAR model of all the constituents in the category indicates that they are expected to have a half-life of 1.92 - 4.55 days. One constituents presented heteroatoms and their BioHCwin half-lives could not be estimated. Of the 15 constituents, no one has a half life of greater than 40 days.

Constituent Name CAS No. BioHCwin half-life (days)
Benzene  000071-43-2 4.55
But-1-ene 000106-98-9 2.75
But-2-ene, cis- 000590-18-1 1.92
But-2-ene, trans- 000624-64-6 1.92
Buta-1,3-diene  000106-99-0 2.82
Butane 000106-97-8 3.46
Carbon Monoxide 000630-08-0
Ethane 000074-84-0 2.55
Ethene  [aka Ethylene] 000074-85-1 2.91
Methane 000074-82-8 3.19
Pentane 000109-66-0 4.03
Prop-1-ene 000115-07-1 2.36
Prop-1-ene, 2-methyl- 000115-11-7 1.92
Propane 000074-98-6 2.97
Propane, 2-methyl- 000075-28-5 3.09