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Environmental fate & pathways

Additional information on environmental fate and behaviour

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Endpoint:
additional information on environmental fate and behaviour
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
study conducted at university laboratories with known expertise in these types of data analyses; published in a highly regarded peer-reviewed environmental science journal; not known if GLP was followed in documenting the work that was performed to run the simulations

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
2012
Report date:
2012

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
Future European polyhaloalkene emissions from mobile air conditioners (MACs) in 2020 were calculated using two scenarios with a lower and upper limit for emission factors for different activities / processes such as filling / refilling, regular / irregular usage, and disposal. The study included the 27 European Union countries plus Croatia, Norway, Switzerland and Turkey (EU-27+). Passenger car numbers predicted for 2020 were taken from the TREMOVE 2.7b database (http://www.tremove.org/). Emissions from additional mobile sources (e.g., trucks) were presumed to account for an additional 10% of emissions.

The Lagrangian Particle Dispersion Model FLEXPART (Version 8.1) was used to simulate atmospheric transport and degradation of European polyhaloalkene and deposition of TFA. Polyhaloalkene reactions with OH and Cl radicals were incorporated in FLEXPART.polyhaloalkene is initially degraded to trifluoroacetyl fluoride (TFF), which is then converted to TFA in water clouds and deposited to the surface by both dry and wet deposition.

The Global Chemistry Transport model CRI-STOCHEM also was used to assess the mass of TFA formed in the atmosphere from emissions of European MACs. The reason for also using CRI-STOCHEM was because FLEXPART does not include a full tropospheric chemistry scheme to allow consideration of an influence of polyhaloalkene on OH concentrations and possible nonlinear responses to its emissions.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Any other information on results incl. tables

Total predicted emissions of polyhalkene for the EU27+ countries for the year 2020 were estimated to be 11.0 and 19.2 Gg yr−1for the low and high emission scenario, respectively, that were used for the model simulations. Annual mean mixing ratios of this refrigerant in Europe as predicted by FLEXPART were between 0.5 and 18 ppt (average 2.6 ppt) and mostly below 1 ppt outside, while CRI-STOCHEM predicted considerably lower mean (1.5 ppt) and maxima (3.7 ppt). These differences can partly be explained by different output grid resolutions and also by different OH levels in the models.

 

Annual global total TFA deposition resulting from polyhaloalkene emissions of European MACs was estimated by FLEXPART to be 18.6 Gg yr−1. The annual total deposition of TFA over the European area was 6.4 Gg yr−1(or 34% of the emissions). In CRI-STOCHEM, annual global total deposition of TFA was 18.4 Gg yr−1. Of this deposition, 42% (7.8 Gg yr−1) was calculated to be deposited in. This greater fraction, as compared with FLEXPART, is likely due to greater OH concentrations, which result in faster degradation of polyhaloalkene in the model.

 

Average annual European total deposition rates of TFA inwere estimated to be 0.65 kg km−2yr−1(European maximum 2.5 kg km−2yr−1, FLEXPART). This agrees well with the CRI-STOCHEM simulated mean European total deposition rates of 0.76 kg km−2yr−1and European maximum values of 1.9 kg km−2yr−1. A considerable fraction of the European emissions of polyhaloalkene was subject to long-range transport toward Asia and across the Sahara desert and deposited as TFA inand in Tropical Africa, respectively. However, annual total deposition rates did not surpass 0.2 kg km−2in these areas. In additional CRI-STOCHEM simulations, emissions of 11 Gg yr−1of polyhaloalkene from the increased TFA mixing ratios over the Iberian Peninsula andby ~0.02 ppt compared with ~0.1 ppt from European polyhaloalkene emissions. No significant influence of North American TFA on the rest of was simulated. However, together with the seasonal analysis of polyhaloalkene and TFA transport from, this suggests that long-range transport of polyhaloalkene from an upwind continent should not be neglected altogether and might be especially important in winter.

 

European mean TFA concentrations in rainwater were estimated by FLEXPART to be 580 ng L−1. Within EU27+, annual mean concentrations were predicted to be highest in theand(1700 ng L−1). CRI-STOCHEM results were slightly higher (800 ng L−1for European mean rainwater concentrations and 2160 ng L−1for European maxima), again related to the faster polyhaloalkene degradation in CRI-STOCHEM. Previously measured concentrations of TFA in rainwater inwere in the range of 10 to 1500 ng L−1. Thus, in the future formerly infrequent high rainwater concentrations will become the average rainwater concentrations and future extreme concentrations might be 2 orders of magnitude larger than previously observed.

 

The no-effect level of TFA in water for the most sensitive algae was determined to be 120 000 ng L−1. Thus, even the largest simulated daily rainwater concentrations will be a factor of 10 smaller than this and European maxima of the annual mean rainwater concentrations will stay a factor of 60 below this critical level.

Applicant's summary and conclusion

Conclusions:
Polyhaloalkene will be released into the atmosphere as it replaces HFC-134a (1,1,1,2-tetrafluoroethane) as a cooling agent in mobile air conditioners (MACs) in the European vehicle fleet. In the atmosphere it is almost completely transformed to the trifluoroacetic acid (TFA). European total polyhaloalkene emissions from MACs after full conversion in 2020 were predicted to range between 11.0 and 19.2 Gg yr−1. Mean deposition rates (wet + dry) of TFA were estimated to be 0.65 to 0.76 kg km−2 yr−1, with a maximum of ~2.0 kg km−2 yr−1. About 30−40% of the European polyhaloalkene emissions were deposited as TFA within Europe, while the remaining fraction was exported toward the Atlantic Ocean, Central Asia, Northern, and Tropical Africa. Largest annual mean TFA concentrations in rainwater were simulated to be as high as 2500 ng L−1. Simulated highest annual mean concentrations are at least 60 times lower than previously determined to be a safe level for the most sensitive aquatic life-forms. Rainwater concentrations during individual rain events would still be an order of magnitude lower than the no effect level.