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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Phototransformation in air

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Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP, non guideline, published in peer reviewed literature, acceptable with restrictions
Principles of method if other than guideline:
Measured data from author and other investigators were quality assessed and then used to develop rate constants for different chemicals. The author applied a least squares analysis of degradation rate constants to calculate a preferred value.
GLP compliance:
no
Remarks:
No data reported
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Estimation method (if used):
No data reported
Light source:
not specified
Details on light source:
No data reported
Details on test conditions:
No data reported
Preliminary study:
No data reported
Test performance:
No data reported
DT50:
0.24 d
Test condition:
Based on a rate constant of 6.68E-11 cm3 molecule-1sec-1 with OH radicals
Results with reference substance:
No data reported

Author reports a recommended rate constant of 6.68E-11 cm3 molecule-1sec-1. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5E5 molecule.cm-3

Conclusions:
The estimated half life of 1,3-butadiene is 0.24 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:

The estimated half life of 1,3-butadiene is 0.24 days based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003). Measured data from 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 1,3-butadiene based on all valid studies at the time of publication.

Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP, information from a review article, acceptable with restrictions
Principles of method if other than guideline:
Measured data from author and other investigators were quality assessed and then used to develop rate constants for different chemicals. The author applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.
GLP compliance:
not specified
Remarks:
No data reported
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Estimation method (if used):
No data reported
Light source:
other: No data reported
Details on light source:
No data reported
Details on test conditions:
No data reported
Preliminary study:
No data reported
Test performance:
No data reported
DT50:
0.5 d
Test condition:
No further details
Results with reference substance:
No data reported

Based on a calculated rate constant of 3.14E-11 cm3molecule-1sec-1, and a hydroxyl radical concentration of 5E5 molecule.cm-3.

Validity criteria fulfilled:
not applicable
Remarks:
Review article
Conclusions:
The estimated half life of 1-butene is 0.5 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:

The estimated half life of 1-butene is 0.5 days based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003). Measured data from 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 1-butene based on all valid studies at the time of publication.

Endpoint:
phototransformation in air
Type of information:
calculation (if not (Q)SAR)
Remarks:
estimated by calculation
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data calculated from several sources, limitations in reporting but considered reliable with restriction
Principles of method if other than guideline:
Measured data from author and other investigators were quality assessed and then used to develop rate constants for different chemicals. The author applied a least squares analysis of degradation rate constants to calculate a preferred value.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Estimation method (if used):
Calculated half life based on a rate constant of 2.37E-12 cm3 / molecule / sec, OH-radical concentration 5E+05 molecules.cm-3 with 24 hour day, as specified in the TGD.
Light source:
not specified
Details on light source:
No data reported
Details on test conditions:
At 298K.
Reference substance:
not specified
Preliminary study:
No data reported
Test performance:
No data reported
DT50:
6.8 d
Test condition:
Calculated half life based on a rate constant of 2.37E-12 cm3 / molecule / sec
Transformation products:
not specified
Results with reference substance:
No data reported
Validity criteria fulfilled:
not specified
Conclusions:
The half life of isobutane has been estimated to be 6.8 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 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 isobutane based on all valid studies at the time of publication.

Endpoint:
phototransformation in air
Type of information:
calculation (if not (Q)SAR)
Remarks:
estimated by calculation
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data calculated from several sources, limitations in reporting but considered reliable with restriction
Principles of method if other than guideline:
Measured data from author and other investigators were quality assessed and then used to develop rate constants for different chemicals. The author applied a least squares analysis of degradation rate constants to calculate a preferred value.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Estimation method (if used):
Calculated half life based on a rate constant of 2.55E-12 cm3 / molecule / sec, OH-radical concentration 5E+05 molecules.cm-3 with 24 hour day, as specified in the TGD.
Light source:
not specified
Details on light source:
No data reported
Details on test conditions:
At 298K.
Reference substance:
not specified
Preliminary study:
No data reported
Test performance:
No data reported
DT50:
6.3 d
Test condition:
Calculated half life based on a rate constant of 2.55E-12 cm3 / molecule / sec
Transformation products:
not specified
Results with reference substance:
No data reported
Validity criteria fulfilled:
not specified
Conclusions:
The half life of butane has been estimated to be 6.3 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:

The half life of butane has been estimated to be 6.3 days based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003). Measured data from 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 butane based on all valid studies at the time of publication.

Endpoint:
phototransformation in air
Type of information:
calculation (if not (Q)SAR)
Remarks:
estimated by calculation
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data calculated from several sources, limitations in reporting but considered reliable with restriction
Principles of method if other than guideline:
Measured data from author and other investigators were quality assessed and then used to develop rate constants for different chemicals. The author applied a least squares analysis of degradation rate constants to calculate a preferred value.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Estimation method (if used):
Calculated half life based on a rate constant of 2.74 E-13 cm3 / molecule / sec, OH-radical concentration 5E+05 molecules.cm-3 with 24 hour day, as specified in the TGD.
Light source:
not specified
Details on light source:
No data reported
Details on test conditions:
At 298K.
Reference substance:
not specified
Preliminary study:
No data reported
Test performance:
No data reported
DT50:
58.6 d
Test condition:
Calculated half life based on a rate constant of 2.74 E-13 cm3 / molecule / sec
Transformation products:
not specified
Results with reference substance:
No data reported
Validity criteria fulfilled:
not specified
Conclusions:
The half life of ethane has been estimated to be 59 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:

The half life of ethane has been estimated to be 59 days based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003). Measured data from 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 ethane based on all valid studies at the time of publication.

Endpoint:
phototransformation in air
Type of information:
calculation (if not (Q)SAR)
Remarks:
estimated by calculation
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data calculated from several sources, limitations in reporting but considered reliable with restriction
Principles of method if other than guideline:
Measured data from author and other investigators were quality assessed and then used to develop rate constants for different chemicals. The author applied a least squares analysis of degradation rate constants to calculate a preferred value.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Estimation method (if used):
Calculated half life based on a rate constant of 8.41E-15 cm3 / molecule / sec, OH-radical concentration 5E+05 molecules.cm-3 with 24 hour day, as specified in the TGD.
Light source:
not specified
Details on light source:
No data reported
Details on test conditions:
At 298K.
Reference substance:
not specified
Preliminary study:
No data reported
Test performance:
No data reported
DT50:
1 907 d
Test condition:
Calculated half life based on a rate constant of 8.41E-15 cm3 / molecule / sec
Transformation products:
not specified
Results with reference substance:
No data reported
Validity criteria fulfilled:
not specified
Conclusions:
The half life of methane has been estimated to be 1907 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:

The half life of methane has been estimated to be 1907 days based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003). Measured data from 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 methane based on all valid studies at the time of publication.

Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP, information from a review article, acceptable with restrictions
Principles of method if other than guideline:
Measured data from author and other investigators were quality assessed and then used to develop rate constants for different chemicals. The author applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.
GLP compliance:
not specified
Remarks:
No data reported
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Estimation method (if used):
No data reported
Light source:
other: No data reported
Details on light source:
No data reported
Details on test conditions:
No data reported
Preliminary study:
No data reported
Test performance:
No data reported
DT50:
0.31 d
Test condition:
No further details
Results with reference substance:
No data reported

Based on a calculated rate constant of 5.14E-11 cm3molecule-1sec-1, and a hydroxyl radical concentration of 5E5 molecule.cm-3.

Validity criteria fulfilled:
not applicable
Remarks:
Review article
Conclusions:
The estimated half life of 2-methylpropene is 7.5 h based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003).
Executive summary:

The estimated half life of 2-methylpropene is 7.5 h based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003). Measured data from 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 2-methylpropene based on all valid studies at the time of publication.

Endpoint:
phototransformation in air
Type of information:
calculation (if not (Q)SAR)
Remarks:
estimated by calculation
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data calculated from several sources, limitations in reporting but considered reliable with restriction
Principles of method if other than guideline:
Measured data from author and other investigators were quality assessed and then used to develop rate constants for different chemicals. The author applied a least squares analysis of degradation rate constants to calculate a preferred value.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Estimation method (if used):
Calculated half life based on a rate constant of 1.18E-12 cm3 / molecule / sec, OH-radical concentration 5E+05 molecules.cm-3 with 24 hour day, as specified in the TGD.
Light source:
not specified
Details on light source:
No data reported
Details on test conditions:
At 298K.
Reference substance:
not specified
Preliminary study:
No data reported
Test performance:
No data reported
DT50:
14 d
Test condition:
Calculated half life based on a rate constant of 1.18E-12 cm3 / molecule / sec
Transformation products:
not specified
Results with reference substance:
No data reported
Validity criteria fulfilled:
not specified
Conclusions:
The half life of propane has been estimated to be 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:

The half life of propane has been estimated to be 14 days based on a recommended reaction rate with hydroxyl radicals and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003). Measured data from 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 propane based on all valid studies at the time of publication.

Description of key information

The phototransformation in air half-lives of the constituents in the category range from 0.24 to 59 days, with methane presenting a half-live of 1907 days, which is 2-3 orders of magnitude higher than the rest.

Key value for chemical safety assessment

Half-life in air:
12.5 d

Additional information

Data from Atkinson (1985) were available for the substances methane, ethane, propane, 2 -methylpropane (isobutane), 2-methylpropene, butane, 1-butene and 1,3 -butadiene. Measured data from 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 the substances based on all valid studies at the time of publication. The phototransformation half-life of methane is 1907 days, ethane is 59 days, propane is 14 days, 2 -methylpropane (isobutane) is 6.8 days, 2 -methylpropene is 0.31 days, butane is 6.3 days, 1-butene is 0.5 days and 1,3 -butadiene is 0.24 days.

The data available for these substances can be read across to other members of the category. The mean of the atmospheric half-life values for the category is 12.5 days (excluding methane of the mean for having a value of orders of magnitude higher than the rest) and this has been used to complete the 'key value for chemical safety assessment'.