Naphtha (petroleum), steam-cracked, light hydrotreated, solvent refined

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

This endpoint is adapted in accordance with REACH Annex XI, Section 1.3 (QSAR). Episuite and the BioHCWin models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Constituents within LOA streams with no heteroatoms (those atoms other than carbon or hydrogen) fall within the applicability domain of this model and it has been recommended by ECHA in the Information Requirement Guidelines.

Reason / purpose for cross-reference:

assessment report

Reason / purpose for cross-reference:

(Q)SAR model reporting (QMRF)

Principles of method if other than guideline:

BioHCwin v1.01 in EPISuite 4.1 (2017) 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). Details on the principles of the method are found in the BioHCwin QMRF/QPRF (see cross-references).

Kinetic 301F model in the OASIS/LMC Catalogic software (v5.11.19) simulates aerobic biodegradation under OECD 301F test conditions and was run for all constituents in the category to determine the identity and persistence properties of the degradation products. Details on the principles of the method are found in the CATALOGIC Kinetic 301F QMRF (see cross-references).

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not applicable

Oxygen conditions:

aerobic

Based on:

other: QSAR calculation

Parameter followed for biodegradation estimation:

other: QSAR calculation

Details on study design:

Not applicable

Compartment:

water

DT50:

>= 1.56 - <= 55.38 d

Type:

not specified

Remarks on result:

other: Result from QSAR prediction. Range based on the measured constituents in the streams.

Transformation products:

not measured

Remarks:

Potential metabolites of aerobic biodegradation and their relative concentrations are predicted using the Kinetic 301F model in the OASIS/LMC Catalogic software (v5.11.19)

Details on transformation products:

All 46 parent constituents were evaluated using the model and this resulted in the prediction of 101 metabolites of which 32 were unique metabolites/degradation products. Review of the log Kow information indicates that none of the parent constituents would be considered to be bioaccumulative and therefore are not PBT. This evaluation is fully reported in the PBT report for the category which is attached to Section 13 of the IUCLID dossier. Two metabolites were considered to be readily biodegradable and 30 not readily biodegradable. However, the primary half-lives indicate that the constituents have a range of half-lives from less than one day to 21 days and only three metabolites had half-lives of over one year. Predicted metabolite structures and abundance are contained in full in the file attached in background material.

Details on results:

Of the 46 parent constituents, 2 have a half-life of greater than 40 days. Details of the constituents and how their BioHCwin half-lives relate to their persistence assessment are found in the BioHCwin QMRF/QPRF, in the PBT report and in the Persistence Weight of Evidence Evaluation (see cross-references). The Persistence Weight of Evidence Evaluation and the PBT Evaluation follow different approaches to assess persistence. Please see both approaches for justification of the approach.

Validity criteria fulfilled:

not applicable

Conclusions:

The predicted BioHCwin half-lives of constituents in these streams range from 1.56 to 55.38 days. Of the 46 constituents, two constituents (cyclopentane and cyclohexane) have a half-life of greater than 40 days. However, these two constituents have experimental and readily biodegradability data that indicates that they are not persistent. The primary half-lives of metabolites have a range of half-lives from less than one day to 22 days and only three metabolites had half-lives of over one year. All the metabolies have log Kow values well below the B threshold and as such are not expected to be PBT or vPvB.

Executive summary:

The water half-lives of measured constituents (at equal or above 0.1% w/w) of this category have been predicted using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005). The predicted BioHCwin half-lives range from 1.56 to 55.38 days. Of the 46 constituents, two constituents (cyclopentane and cyclohexane) have a half-life of greater than 40 days. However, these two constituents have experimental and readily biodegradability data that indicates that they are not persistent.

Potential metabolites of aerobic biodegradation and their relative concentrations have been predicted using the Kinetic 301F model in the OASIS/LMC Catalogic software (v5.11.19). The primary half-lives of metabolites have a range of half-lives from less than one day to 22 days and only three metabolites had half-lives of over one year. All the metabolies have log Kow values well below the B threshold and as such are not expected to be PBT or vPvB.

Reference 2

Endpoint:

biodegradation in water: sediment simulation testing

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

This endpoint is adapted in accordance with REACH Annex XI, Section 1.3 (QSAR). The constituents in the category have a low potential for adsorption to sediments. This indicates that the surface water (measured or predicted) biodegradation rates would be applicable to sediment. An evaluation extrapolation factor of 4 was implemented to the water half-lives to calculate sediment half-lives for screening purposes, according to Boethling et. al (1995). Measured freshwater biodegradation rates were obtained from the Concawe Report (2019), which provides water experimental primary biodegradation half-lives for petroleum substances from reliable sources, including peer-reviewed studies. BioHCWin model biodegradation rates were used for constituents for which no experimental data was available. The BioHCwin model is a well documented and commonly used QSARs for predicting the biodegradation potential of hydrocarbon chemicals. Constituents within LOA streams with no heteroatoms (those atoms other than carbon or hydrogen) fall within the applicability domain of this model and it has been recommended by ECHA in the Information Requirement Guidelines.

Reason / purpose for cross-reference:

assessment report

Reason / purpose for cross-reference:

(Q)SAR model reporting (QMRF)

Principles of method if other than guideline:

An evaluation extrapolation factor of 4 was implemented to the water half-lives to calculate sediment half-lives for screening purposes, acording to Boethling et. al (1995). Measured freshwater biodegradation rates were obtained from the Concawe Report (2019), which provides water experimental primary biodegradation half-lives for petroleum substances from reliable sources, including peer-reviewed studies. BioHCWin model v1.01 (EPISuite 4.1, 2017) freshwater biodegradation rates were used for constituents for which no experimental freshwater half-life was available. 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). Details on the principles of the method are found in the BioHCwin QMRF/QPRF (see cross-references).

Kinetic 301F model in the OASIS/LMC Catalogic software (v5.11.19) (Dimitrov et al., 2011a, 2011b) simulates aerobic biodegradation under OECD 301F test conditions and was run for all constituents in the category to determine the identity and persistence properties of the degradation products. Since the sediment is considered an aerobic system, similar methabolic pathways are considered to occur in water and sediment. An evaluation extrapolation factor of 4 was implemented to the metabolite primary water half-lives to calculate metabolite sediment primary half-lives for screening purposes, acording to Boethling et. al (1995). Details on the principles of the method are found in the CATALOGIC Kinetic 301F QMRF (see cross-references).

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

Key result

Compartment:

sediment

DT50:

>= 12.44 - <= 176.4 d

Remarks on result:

other: Result from 1:4 extrapolation from measured freshwater half-lives. Range based on the measured constituents in the streams.

Key result

Compartment:

sediment

DT50:

>= 6.24 - <= 221.52 d

Remarks on result:

other: Result from 1:4 extrapolation from QSAR predicted freshwater half-lives. Range based on the measured constituents in the streams.

Transformation products:

not measured

Remarks:

Potential metabolites of aerobic biodegradation and their relative concentrations are predicted using the Kinetic 301F model in the OASIS/LMC Catalogic software (v5.11.19)

Details on transformation products:

All 46 parent constituents were evaluated using the model and this resulted in the prediction of 101 metabolites of which 32 were unique metabolites/degradation products. Review of the log Kow information indicates that none of the parent constituents would be considered to be bioaccumulative and therefore are not PBT. This evaluation is fully reported in the PBT report for the category which is attached to Section 13 of the IUCLID dossier. Two metabolites were considered to be readily biodegradable and 30 not readily biodegradable. However, the primary half-lives indicate that the constituents have a range of half-lives fromless than 4 days to 88 days and only three metabolites had half-lives of over one year. Predicted metabolite structures and abundance are contained in full in the file attached in background material.

Details on results:

Of the 46 parent constituents, seven have a half-life of greater equal or greater than 120 days. Details of the constituent half-lives and how these value relate to their persistence assessment are found in the Persistence Weight of Evidence Evaluation (see cross-reference).

Validity criteria fulfilled:

not applicable

Conclusions:

The sediment half-lives of measured parent constituents of this category range from 6.24 to 221.52 days. Of the 46 parent constituents, seven have a half-life of greater equal or greater than 120 days. However, most of the parent constituents have a log Koc of < 3 which indicates that they will not preferentially adsorb to sediment particles and are therefore not considered to be persistent in sediments. The primary half-lives of metabolites have a range of half-lives from less than 4 days to 88 days and only three metabolites had half-lives of over one year. All the metabolies have log Kow values well below the B threshold and as such are not expected to be PBT or vPvB.

Executive summary:

The sediment half-lives of the category constituents (at equal or above 0.1% w/w)  were extrapolated from measured (Concawe report, 2019) and predicted (EPISUITE v4.11 BioHCwin model, 2017) freshwater half-lives using an extrapolation factor of 4 (Boethling et al., 1995). The sediment half-lives of measured parent constituents of this category range from 6.24 to 221.52 days. Of the 46 parent constituents, seven have a sediment half-life of equal to or greater than 120 days. However, most of the parent constituents have a log Koc of < 3 which indicates that they will not preferentially adsorb to sediment particles and are therefore not considered to be persistent in sediments.

Potential metabolites of aerobic biodegradation and their relative concentrations have been predicted using the Kinetic 301F model in the OASIS/LMC Catalogic software (v5.11.19). The primary half-lives of metabolites have a range of half-lives from less than 4 days to 88 days and only three metabolites had half-lives of over one year. All the metabolies have log Kow values well below the B threshold and as such are not expected to be PBT or vPvB.

Reference 3

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

The Concawe report (see cross-reference) provides freshwater and marine water experimental primary biodegradation half-lives for hydrocarbons relevant to petroleum substances. These experimental data are all referenced in the document and have been obtained from reliable sources, including including peer-reviewed studies.

Reason / purpose for cross-reference:

assessment report

Principles of method if other than guideline:

Consistent with ECHA REACH Guidance Chapter R.11 PBT/vPvB assessment (ECHA 2017a), the PBT/vPvB assessment in the Concawe report was performed using the hydrocarbon block method, using information from representative constituents/structures. Measured data and model predictions (based on the Concawe library of representative constituents (~16000 structures)) were evaluated for representative structures associated with each HCB to develop an evidence-based conclusion regarding PBT/vPvB properties.

Over 1,000 data points for hydrocarbons relevant to petroleum substances are available for freshwater and marine water experimental primary biodegradation half-lives. These data are from studies carried out since Howard et al. (2005) published the BioHCwin model. BioHCwin was based on collated degradation data available at the time, based on an extensive literature review. The experimental data discussed in this report represents a large fraction of new aquatic degradation data that has become available since 2005, and was therefore not used in the training set for BioHCwin. This new experimental data includes marine and freshwater biodegradation half-lives from 14 different sources, including peer-reviewed studies.

GLP compliance:

no

Remarks:

Data obtained from the Concawe PBT report, which references experimental data that come from ecotoxicity tests but also peer-reviewed studies

Inoculum or test system:

other: natural water: freshwater and marine

Key result

Compartment:

natural water: freshwater

DT50:

>= 3.11 - <= 44.1 d

Remarks on result:

other: Experimental values available for 32 out of the 46 constituents of the category

Key result

Compartment:

natural water: marine

DT50:

>= 0.37 - <= 29.04 d

Remarks on result:

other: Experimental values available for 15 out of the 46 constituents of the category

Transformation products:

no

Details on results:

Details of the constituents with measured half-lives and how these value relate to their persistence assessment are found in the PBT report and in the Persistence Weight of Evidence Evaluation (see cross-reference).

Conclusions:

Out of the 46 measured constituents of the category (at equal or above 0.1%), freshwater half-lives are available for 32 constituents and range from 3.11 to 44.1 d, and marine water half-lives are available for 15 constituents and range from 0.37 to 29.04 d.
Only three of the 46 constituents have half-lives of >40 days (2-methylpropane, 2-methylbutane and 2,2,3-trimethylbutane). These three substances are either gases (2-methylpropane) and/or have a high vapour pressure with relatively low log Kow (<4) which indicates that if released to the environment they will not reside in the water, sediment or soil compartment and would be released to air. Abiotic processes indicated that once in the air compartment they will be degraded by sunlight in less than 6 days.

This indicates that these constituents are not persistent and will easily degrade in the environment, as the three constituents with half-lives of >40 days are likely to be broken down by abiotic processes.

Executive summary:

The Concawe report provides water experimental primary biodegradation half-lives for petroleum substances from reliable sources, including peer-reviewed studies. Out of the 46 measured constituents of the category (at equal or above 0.1% w/w), freshwater half-lives are available for 32 constituents and range from 3.11 to 44.1 d (with 3 values above 40 d), and marine water half-lives are available for 15 constituents and range from 0.37 to 29.04 d. The three constituents with half-lives of >40 days were determined to be not persistent because they volatilise easily, have a low adsorption potential and because abiotic processes will degrade them in air. Therefore, the constituents in the category UVCBs will easily degrade in the environment and would not be considered to be persistent.

Reference 4

Endpoint:

biodegradation in water and sediment: simulation testing, other

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Combination of experimental data and QSAR calculations

Justification for type of information:

Several lines of evidence are used to evaluate the degradation potential of the constituents reported in UVCBs. This includes any experimental degradation data available, degradation QSARs, and any other data that would influence the ultimate fate of the constituents in the environment including the log Kow for bioaccumulation potential and the log Koc to evaluate the potential of the constituents to adsorb to sediment and soil particles. See cross-reference.

Reason / purpose for cross-reference:

assessment report

Principles of method if other than guideline:

Several lines of evidence are used to evaluate the degradation potential of the constituents reported in UVCBs. This includes any experimental degradation data available (see Concawe PBT report in cross-reference), degradation QSARs, and any other data that would influence the ultimate fate of the constituents in the environment including the log Kow for bioaccumulation potential and the log Koc to evaluate the potential of the constituents to adsorb to sediment and soil particles. See Persistence Weight of Evidence Evaluation in cross-reference.

Compartment:

water

DT50:

>= 1.56 - <= 55.38 d

Remarks on result:

other: Result from QSAR prediction. Range based on the measured constituents in the streams

Compartment:

sediment

DT50:

>= 6.24 - <= 221.52 d

Remarks on result:

other: Result from 1:4 extrapolation from experimental and QSAR predicted freshwater half-lives. Range based on the measured constituents in the streams.

Transformation products:

not measured

Remarks:

Potential metabolites of aerobic biodegradation and their relative concentrations are predicted using the Kinetic 301F model in the OASIS/LMC Catalogic software (v5.11.19)

Details on transformation products:

All 46 parent constituents were evaluated using the model and this resulted in the prediction of 101 metabolites of which 32 were unique metabolites/degradation products. Review of the log Kow information indicates that none of the parent constituents would be considered to be bioaccumulative and therefore are not PBT. This evaluation is fully reported in the PBT report for the category which is attached to Section 13 of the IUCLID dossier. Two metabolites were considered to be readily biodegradable and 30 not readily biodegradable. However, the primary half-lives indicate that the constituents have a range of half-lives fromless than 4 days to 88 days and only three metabolites had half-lives of over one year.

Details on results:

The persistence assessment for this category was conducted by evaluating the individual constituents reported by the registrants (co- and lead) at a concentration of ≥ 0.1% (w/w). The degradation potential in surface water indicated that the constituents would not be persistent if released to water. The category constituents’ degradation evaluation indicated that when physico-chemical properties (e.g., volatilisation), abiotic and biotic processes are addressed collectively none of the constituents would persist in surface water. Therefore, simulation testing on ultimate degradation in surface water does not appear to be scientifically necessary. The adsorption/desorption potential evaluated for the category constituents using the log Koc screening criterion value of 3 indicates that the constituents do not have significant adsorption potential. Therefore, sediment and soil biodegradation simulation tests do not appear to be scientifically necessary as the category constituents degrade rapidly in the environment and there is very low potential for them to adsorb to sediment and soil particles.

Conclusions:

In accordance to REACH Annex XI, Section 1.2 the surface water, sediment and soil biodegradation simulation studies are not required because the weight of evidence indicates that the constituents in the category would degrade rapidly in the environment and because their potential for adsorption to sediment and soil particles is considered to be low based on the log Koc criteria of 3.

Executive summary:

The persistence assessment for this category was conducted by evaluating the individual constituents reported by the registrants (co- and lead) at a concentration of ≥ 0.1% (w/w).

The degradation potential in surface water indicated that the constituents would not be persistent if released to water. The category constituents’ degradation evaluation indicated that when physico-chemical properties (e.g., volatilisation), abiotic and biotic processes are addressed collectively none of the constituents would persist in surface water. Therefore, simulation testing on ultimate degradation in surface water does not appear to be scientifically necessary.

The adsorption/desorption potential evaluated for the category constituents using the log Koc screening criterion value of 3 indicates that the constituents do not have significant adsorption potential. Therefore, sediment and soil biodegradation simulation tests do not appear to be scientifically necessary as the category constituents degrade rapidly in the environment and there is very low potential for them to adsorb to sediment and soil particles.

In accordance to REACH Annex XI, Section 1.2 the surface water, sediment and soil biodegradation simulation studies are not required because the weight of evidence indicates that the constituents in the category would degrade rapidly in the environment and because their potential for adsorption to sediment and soil particles is considered to be low based on the log Koc criteria of 3.

Description of key information

It is not technically feasible to perform simulation testing on ultimate degradation in sediment, surface water or soil on UVCBs. Current test procedures are not suitable for the characterisation of the degradation potential and potential metabolite formation of these substances due to their complex compositions. For this reason, the persistence assessment for this category was conducted by evaluating the individual constituents reported by the registrants (co- and lead) at a concentration of ≥ 0.1% (w/w).

The degradation potential in surface water indicated that the constituents would not be persistent if released to water. The category constituents’ degradation evaluation indicated that when physico-chemical properties (e.g., volatilization), abiotic and biotic processes are addressed collectively none of the constituents would persist in surface water. Therefore, simulation testing on ultimate degradation in surface water does not appear to be scientifically necessary.

The adsorption/desorption potential evaluated for the category constituents using the log Koc screening criterion value of 3 indicates that the constituents do not have significant adsorption potential. Therefore, sediment and soil biodegradation simulation tests do not appear to be scientifically necessary as the category constituents degrade rapidly in the environment and there is very low potential for them to adsorb to sediment and soil particles.

Additional information

The water half-lives of measured constituents (at equal or above 0.1% w/w) of this category have been obtained from the Concawe report (2019), which lists measured freshwater and marine water half-lives of petroleum substances from relevant sources, and have been predicted using the EPISUITE v4.11 BioHCwin model (2017), which uses methodology described by Howard et al. (2005) to calculate freshwater half-lives.

Out of the 46 measured constituents of the category (at equal or above 0.1% w/w), freshwater half-lives are available for 32 constituents and range from 3.11 to 44.1 d (with 3 values above 40 d), and marine water half-lives are available for 15 constituents and range from 0.37 to 29.04 d. The three constituents with half-lives of >40 days were determined to be not persistent because they volatilise easily, have a low adsorption potential and because abiotic processes will degrade them in air. The predicted BioHCwin half-lives range from 1.56 to 55.38 days in surface water. Of the 46 constituents, two constituents (cyclopentane and cyclohexane) have half-lives of > 40 days but have experimental and readily biodegradability data that indicates that they are not persistent. Therefore, the constituents in the category UVCBs will easily degrade in the environment and would not be considered to be persistent.

It is not technically feasible to perform simulation testing on ultimate degradation in sediment on UVCBs. Current test procedures are not suitable for the characterisation of the degradation potential and potential metabolite formation of these substances due to their complex compositions. Based on an extrapolation from the measured or QSAR predicted freshwater half-lives using an extrapolation factor of 1:4 (Boethling et al., 1995), the sediment half-lives of measured parent constituents of this category range from 4.08 to 221.52 days. Of the 46 parent constituents, seven have a half-life of equal or greater than 120 days. However, most of the parent constituents have a log Koc of < 3 which indicates that they will not preferentially adsorb to sediment particles and are therefore not considered to be persistent in sediments.

The metabolites of the 46 parent constituents have been determined and quantified using the Kinetic 301F model in the OASIS/LMC Catalogic software (v5.11.19). The metabolites water and sediment half-lives range from less than 1 day to 88 days and only three metabolites had half-lives of over one year. All the metabolies have log Kow values well below the B threshold and as such are not expected to be PBT or vPvB.