Xylene

Phototransformation in air

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

phototransformation in air

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP, guidline not known, information from published review article, acceptable with restrictions

Principles of method if other than guideline:

The author used data from other investigators. This data was generated using two methods: absolute and relative constant techniques. The author then applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.

GLP compliance:

no

Specific details on test material used for the study:

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

Estimation method (if used):

The rate constants were taken from experiments using absolute techniques (flash photolysis) and relative constant techniques

Light source:

not specified

Details on light source:

Data not reported

Details on test conditions:

Data not reported

Reference substance:

not specified

Preliminary study:

Data not reported

Test performance:

Data not reported

DT50:

2.14 d

Test condition:

Author reports a recommended rate constant of 7.5E-12 cm3 molecule-1sec-1. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5E5 molecule.cm-3

DT50:

1.799 d

Test condition:

Author reports a recommended rate constant of 5.9463 E-12 cm3/molecule/second. Half life is calculated based on this rate constant

Transformation products:

not specified

Results with reference substance:

Data not reported

N/A

Validity criteria fulfilled:

not applicable

Remarks:

non-standard test

Conclusions:

The estimated half life of ethylbenzene is 2.14 days based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003).

Executive summary:

Measured data from the author and other investigators were quality assessed and then used to develop rate constants for different chemicals. Therefore, this value represents a valid rate constant for ethylbenzene based on all valid studies at the time of publication.

Reference 2

Endpoint:

phototransformation in air

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2021

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 AOPWIN models are well documented and commonly used QSARs for predicting the potential indirect photolysis of chemicals in the atmosphere. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.

Qualifier:

no guideline required

Principles of method if other than guideline:

The Atmospheric Oxidation Program for Microsoft Windows (AOPWIN) estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals.  It also estimates the rate constant for the gas-phase reaction between ozone and olefinic/acetylenic compounds. The rate constants estimated by the program are then used to calculate atmospheric half-lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone. The author used data from other investigators. This data was generated using two methods: absolute and relative constant techniques. The author then applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.

GLP compliance:

no

Specific details on test material used for the study:

SMILES: c(cccc1C)(c1)C

Estimation method (if used):

The rate constants were taken from experiments using absolute techniques (flash photolysis) and relative constant techniques.

Details on light source:

N/A

Details on test conditions:

N/A

Preliminary study:

N/A

Test performance:

N/A

Key result

DT50:

0.789 d

Test condition:

Author reports a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Remarks on result:

other: Result from QSAR

Transformation products:

not specified

Results with reference substance:

Data not reported

N/A

Validity criteria fulfilled:

not applicable

Remarks:

non-standard test

Conclusions:

The estimated half life of the substance is 0.789 days based on a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Executive summary:

The indirect photolysis half-life was estimated using the EPISUITE v4.11 program and the methodology described by Atkinson et al. (1985). The estimated half life of the substance is 0.789 days based on a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Reference 3

Endpoint:

phototransformation in air

Type of information:

calculation (if not (Q)SAR)

Remarks:

estimated by calculation

Adequacy of study:

key study

Study period:

1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP, guidline not known, information from published review article, acceptable with restrictions

Principles of method if other than guideline:

The author used data from other investigators. This data was generated using two methods: absolute and relative constant techniques. The author then applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.

GLP compliance:

no

Specific details on test material used for the study:

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

Estimation method (if used):

The rate constants were taken from experiments using absolute techniques (flash photolysis) and relative constant techniques.

Light source:

not specified

Details on light source:

Data not reported

Details on test conditions:

Data not reported

Reference substance:

not specified

Preliminary study:

Data not reported

Test performance:

Data not reported

Key result

DT50:

23.2 h

Test condition:

Author reports a recommended rate constant of 1.66 E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Transformation products:

not specified

Results with reference substance:

Not applicable

N/A

Validity criteria fulfilled:

not applicable

Remarks:

non standard study

Conclusions:

The estimated half life of m-xylene is 23.2 hours based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003).

Executive summary:

Measured data from the author and other investigators were quality assessed and then used to develop rate constants for different chemicals. Therefore, this value represents a valid rate constant for m-xylene based on all valid studies at the time of publication.

Reference 4

Endpoint:

phototransformation in air

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2021

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 AOPWIN models are well documented and commonly used QSARs for predicting the potential indirect photolysis of chemicals in the atmosphere. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.

Qualifier:

no guideline required

Principles of method if other than guideline:

The Atmospheric Oxidation Program for Microsoft Windows (AOPWIN) estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals.  It also estimates the rate constant for the gas-phase reaction between ozone and olefinic/acetylenic compounds. The rate constants estimated by the program are then used to calculate atmospheric half-lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone. The author used data from other investigators. This data was generated using two methods: absolute and relative constant techniques. The author then applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.

GLP compliance:

no

Specific details on test material used for the study:

SMILES: c(c(ccc1)C)(c1)C

Estimation method (if used):

The rate constants were taken from experiments using absolute techniques (flash photolysis) and relative constant techniques.

Details on light source:

N/A

Details on test conditions:

N/A

Key result

DT50:

1.643 d

Test condition:

Author reports a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Remarks on result:

other: Result from QSAR

Transformation products:

not specified

Results with reference substance:

Data not reported

N/A

Validity criteria fulfilled:

not applicable

Remarks:

non-standard test

Conclusions:

The estimated half life of the substance is 1.643 days based on a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Executive summary:

The indirect photolysis half-life was estimated using the EPISUITE v4.11 program and the methodology described by Atkinson et al. (1985). The estimated half life of the substance is 1.643 days based on a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Reference 5

Endpoint:

phototransformation in air

Type of information:

calculation (if not (Q)SAR)

Remarks:

estimated by calculation

Adequacy of study:

key study

Study period:

1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP, guidline not known, information from published review article, acceptable with restrictions

Principles of method if other than guideline:

The author used data from other investigators. This data was generated using two methods: absolute and relative constant techniques. The author then applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.

GLP compliance:

no

Specific details on test material used for the study:

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

Estimation method (if used):

The rate constants were taken from experiments using absolute techniques (flash photolysis) and relative constant techniques.

Light source:

not specified

Details on light source:

Data not reported

Details on test conditions:

Data not reported

Reference substance:

not specified

Preliminary study:

Data not reported

Test performance:

Data not reported

Key result

DT50:

1.09 d

Test condition:

Author reports a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Transformation products:

not specified

Results with reference substance:

Data not reported

N/A

Validity criteria fulfilled:

not applicable

Remarks:

non-standard test

Conclusions:

The estimated half life of o-xylene is 1.09 days based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003).

Executive summary:

Measured data from the author and other investigators were quality assessed and then used to develop rate constants for different chemicals. Therefore, this value represents a valid rate constant for o-xylene based on all valid studies at the time of publication.

Reference 6

Endpoint:

phototransformation in air

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2021

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 AOPWIN models are well documented and commonly used QSARs for predicting the potential indirect photolysis of chemicals in the atmosphere. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.

Qualifier:

no guideline required

Principles of method if other than guideline:

The Atmospheric Oxidation Program for Microsoft Windows (AOPWIN) estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals.  It also estimates the rate constant for the gas-phase reaction between ozone and olefinic/acetylenic compounds. The rate constants estimated by the program are then used to calculate atmospheric half-lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone. The author used data from other investigators. This data was generated using two methods: absolute and relative constant techniques. The author then applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.

GLP compliance:

no

Specific details on test material used for the study:

SMILES: c(ccc(c1)C)(c1)C

Estimation method (if used):

The rate constants were taken from experiments using absolute techniques (flash photolysis) and relative constant techniques.

Details on light source:

N/A

Details on test conditions:

N/A

Preliminary study:

N/A

Test performance:

N/A

Key result

DT50:

1.643 d

Test condition:

Author reports a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Remarks on result:

other: Result from QSAR

Transformation products:

not specified

Results with reference substance:

Data not reported

N/A

Validity criteria fulfilled:

not applicable

Remarks:

non-standard test

Conclusions:

The estimated half life of the substance is 1.643 days based on a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Executive summary:

The indirect photolysis half-life was estimated using the EPISUITE v4.11 program and the methodology described by Atkinson et al. (1985). The estimated half life of the substance is 1.643 days based on a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3..

Reference 7

Endpoint:

phototransformation in air

Type of information:

calculation (if not (Q)SAR)

Remarks:

estimated by calculation

Adequacy of study:

key study

Study period:

1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP, guidline not known, information from published review article, acceptable with restrictions

Principles of method if other than guideline:

The author used data from other investigators. This data was generated using two methods: absolute and relative constant techniques. The author then applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.

GLP compliance:

no

Specific details on test material used for the study:

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

Estimation method (if used):

The rate constants were taken from experiments using absolute techniques (flash photolysis) and relative constant techniques.

Light source:

not specified

Details on light source:

Data not reported

Details on test conditions:

Data not reported

Reference substance:

no

Preliminary study:

Data not reported

Test performance:

Data not reported

Key result

DT50:

1.06 d

Test condition:

Author reports a recommended rate constant of 1.52 E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Transformation products:

not specified

Results with reference substance:

Not applicable

N/A

Validity criteria fulfilled:

not applicable

Remarks:

non standard study

Conclusions:

The estimated half life of p-xylene is 1.06 days based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003).

Executive summary:

Measured data from the author and other investigators were quality assessed and then used to develop rate constants for different chemicals. Therefore, this value represents a valid rate constant for p-xylene based on all valid studies at the time of publication.

Reference 8

Endpoint:

phototransformation in air

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2021

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 AOPWIN models are well documented and commonly used QSARs for predicting the potential indirect photolysis of chemicals in the atmosphere. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.

Qualifier:

no guideline required

Principles of method if other than guideline:

The Atmospheric Oxidation Program for Microsoft Windows (AOPWIN) estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals.  It also estimates the rate constant for the gas-phase reaction between ozone and olefinic/acetylenic compounds. The rate constants estimated by the program are then used to calculate atmospheric half-lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone. The author used data from other investigators. This data was generated using two methods: absolute and relative constant techniques. The author then applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.

GLP compliance:

no

Specific details on test material used for the study:

N/A

Estimation method (if used):

The rate constants were taken from experiments using absolute techniques (flash photolysis) and relative constant techniques.

Details on light source:

N/A

Details on test conditions:

N/A

Preliminary study:

N/A

Test performance:

N/A

Key result

DT50:

1.643 d

Test condition:

Author reports a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Remarks on result:

other: Result from QSAR

Transformation products:

not specified

Results with reference substance:

Data not reported

N/A

Validity criteria fulfilled:

not applicable

Remarks:

non-standard test

Conclusions:

The estimated half life of the substance is 1.643 days based on a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Executive summary:

The indirect photolysis half-life was estimated using the EPISUITE v4.11 program and the methodology described by Atkinson et al. (1985). The estimated half life of the substance is 1.643 days based on a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.

Description of key information

O-, m-, and p-Xylene and Ethylbenzene are constituents of the Reaction Mass of Ethylbenzene and Xylene. The estimated half lives of the o-, m-, and p-xylene isomers and Ethylbenzene is between 1-2 days based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the ECHA guidance (2010).

Key value for chemical safety assessment

Half-life in air:

2 d

Additional information

The Reaction Mass of Ethylbenzene and Xylenes is expected to degrade by indirect photolysis in air. The dominant process is by reaction with hydroxyl radicals. Using rate constants recommended by Atkinson (1985) for the reaction rate with hydroxyl radicals half lives of around 1 -2 days are calculated for each of the xylene isomers and ethylbenzene. These data indicate that indirect photolysis is expected to be a significant route of removal from the environment.