Registration Dossier

Environmental fate & pathways

Additional information on environmental fate and behaviour

Administrative data

Endpoint:
additional information on environmental fate and behaviour
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented, meets generally accepted scientific principles, acceptable for assessment.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1997

Materials and methods

Principles of method if other than guideline:
Calculation of the Ozone Depletion Potential (ODP) and atmospheric and total lifetimes of bromochloromethane using a two-dimensional chemical-transport model of the troposphere and stratosphere.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): chlorobromomethane, CH2ClBr

Results and discussion

Any other information on results incl. tables

The model-estimated atmospheric lifetime for CH2ClBr due to atmospheric chemical loss is 0.4 years (146 days). The main removal process, which represents a 99%, is the reaction with OH radicals. The atmospheric photolysis has only a minor effect on the atmospheric lifetimes (1%). The lifetime for ocean loss currently has a range of 0.43 -0.65 years. This results in a total lifetime of 0.21 -0.25 years.

The Ozone Depletion Potential (OPD) of chlorobromomethane is determined to be between 0.11 and 0.13.

Applicant's summary and conclusion

Conclusions:
The Ozone Depletion Potential (OPD) of chlorobromomethane is 0.11-0.13. The estimated atmospheric lifetime and the total lifetime are estimated to be of 0.4 and 0.21-0.25 years, respectively.
Executive summary:

As Chlorobromomethane (CH2ClBr) is a chemical containing chlorine and bromine, it is important to determine the potential environmental effect from use and emissions, including effects on stratospheric ozone. The Ozone Depletion Potential (ODP), which is an important measure of the potential effects on ozone, is evaluated using a two-dimensional chemical-transport model of the troposphere and stratosphere. The results show that the main removal process (99%) in the atmosphere is the reaction with OH radiocals, while photolysis has only a minor (1%) effect on the atmospheric lifetime of the compound. The atmospheric lifetime of CH2ClBr due to atmospheric reactions is evaluated to be 0.4 years (146 days). However, oceanic losses are likely to be important for CH2ClBr. The lifetime for ocean loss currently has a range of 0.43 -0.65 years. This results in a total lifetime of 0.21 -0.25 years. The OPD of chlorobromomethane including the effects of the ocean sink is 0.11 -0.13. On the basis of the reported OPD, it can be concluded that chlorobromomethane is an ozone depleting substance.