Propanenitrile, 2,3,3,3-tetrafluoro-2-(trifluoromethyl)-

Additional information on environmental fate and behaviour

Administrative data

Endpoint:

additional information on environmental fate and behaviour

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

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

phototransformation in air

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: non-GLP, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline available

Principles of method if other than guideline:

Indirect photolysis with *OH radical produced from ozone.

GLP compliance:

no

Light source:

other: Mercury-Xenon

Details on light source:

- Lamp: Oriel Instruments UV Lamp, Model 66921 equipped with a 480 W Mercury Xenon bulb
- Emission wavelength spectrum: See Figure 1
- Filters used and their purpose: Manufacturer specifies a transmission range of 200-2500 nm for lamp window. No additional filtration. Some attenuation of IR is expected at quartz window of gas cell.

Duration:

47 min

Temp.:

27 °C

Reference substance:

yes

Remarks:

methane or HFC-125

DT50:

21 yr

Test condition:

based on average of four measurements

Transformation products:

yes

Remarks:

No fluorinated products were detected after reaction.

Results with reference substance:

Only fluorinated product detected by GC-MA above 0.015 ppm LOQ. <1% of parent.

Concentrations of L-21609 and methane were monitored in the absence of UV/Visible light to assess the background effect of dark reactions (adsorption to or reaction with the cell walls). Less than 1% losses of both L-21609 and reference substance (methane or pentafluoroethane) were observed (Figures 2 - 5). Based on this result L-21609 does not react appreciably with either ozone or water vapor (present at 1000 ppmv) over the duration of this experiment.

 

On irradiation, linear declines in concentration of ozone, L-21609 and methane were observed for the first 40 minutes of illumination. Regression of this portion of the decay curves produced the following equations:

 

Run 1:

HFC-125: C/Co = -0.00126 * time + 0.05535, R-sq = 0.988

L-21609: C/Co = -0.00114 * time + 0.03118, R-sq = 0.868

k(L-21609)/k(HFC-125) = 0.90

lifetime( L-21609) = k(L-21609)/k(HFC-125) * lifetime(HFC-125 [28.2y]) = 31y

 

Run 2:

methane: C/Co = -0.00469 * time + 0.19135, R-sq = 0.98

L-21609: C/Co = -0.00144 * time + 0.04448, R-sq = 0.98

k(L-21609)/k(methane) = 0.31

lifetime (L-21609) = k(L-21609)/k(methane) * lifetime (methane [11.2y]) = 36y

 

Run 3:

methane: C/Co = -0.00454 * time + 0.16351, R-sq = 0.95

L-21609: C/Co = -0.00167 * time + 0.04313, R-sq = 0.76

k(L-21609)/k(methane) = 0.37

lifetime (L-21609) = 30y

Run 3:

methane: C/Co = -0.00497 * time + 0.40467, R-sq = 0.992

L-21609: C/Co = -0.00251 * time + 0.16037, R-sq = 0.96

k(L-21609)/k(methane) = 0.51

lifetime (L-21609) = 22y

 

The average atmospheric lifetime of L-21609 is 30 years.

Conclusions:

The atmospheric lifetime of L-21609 with respect to *OH is 30 years.

Executive summary:

The atmospheric lifetime of L-21609 with respect to *OH was determined using pentafluoroethane or methane as reference substance in a 10-m FTIR gas cell. Hydroxyl radical was produced by irradiation of ozone in the presence of water vapor. Temperature was 26-28 °C, and pressure was brought to approximately 1 atmosphere with humidified nitrogen. Progress of the reaction was monitored by FTIR spectroscopy according to EPA method 320. Losses of reference substance and L-21609 were <1% due to dark reactions, indicating negligible reaction with ozone or water vapor. In one trial, gas samples taken during the irradiation revealed no increase in volatile fluorinated gas due to photoreaction. Based on the accepted atmospheric lifetimes for HFC-125 (29 y) and methane (12 years), the average atmospheric lifetime of L-21609 with respect to *OH is 30 years.

 

The study followed sound scientific principles. The study overall was not conducted to GLP criteria. Composition of the reaction mixture is not specified in the report, however the relative reaction rate calculation mitigates the need for this detail. The study assumes phototransformation solely due to hydroxyl radical and does not take direct phototransformation into account. Therefore, this study is classified as reliable with restrictions. It is suitable for entry into a weight of evidence for Risk Assessment, Classification & Labeling, and PBT Analysis.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

IR spectrum obtained according to EPA method 320, integrated according to Hodnebrog et al (2013) (Rev. Geophys., 51, 300-378) and used to estimate Global warming potential according to IPCC methods.

GLP compliance:

no

Type of study / information:

Infrared spectrum, global warming potential

Test material

Test material information

Constituent 1

Reference substance name:

C4 F-isonitrile

IUPAC Name:

C4 F-isonitrile

Test material form:

other: gas

Details on test material:

- Name of test material (as cited in study report): L-21609
- Substance type: Mono-constituent
- Physical state: gas
- Storage condition of test material: as a pressurized liquid

Results and discussion

Any other information on results incl. tables

See attachment for IR spectrum of C4 F-isonitrile. The corrected radiative forcing is 0.225 W∙m^-2∙ppbV^-1. Assuming an atmospheric lifetime of 30 years, the 100-year GWP of C4 F-isonitrile is 2100.

Applicant's summary and conclusion

Conclusions:

The 100-year GWP of C4 F-isonitrile is 2100

Executive summary:

Potential effects of C4 F-isonitrile on climate were addressed by calculation of 100-year integrated global warming potential (100-year GWP). A high-resolution infrared spectrum was taken using a protocol following EPA method 320. Integrated IR cross-section and radiative forcing were calculated using the approach of Hodnebrog et al. (Rev. Geophys. 51, 300-378). Atmospheric lifetime was determined in this study to be 30 years (reported elsewhere in this dossier). GWP was calculated for this study summary as per IPCC AR5 (2013). The integrated instantaneous radiative forcing was 0.225 W∙m^-2∙ppbV^-1. The 100-year GWP is 2100.

 

No testing guideline has been promulgated to determine global warming potential. However, the infrared cross-section data were collected according EPA method 320, and the radiative forcing and GWP were calculated by methods accepted by IPCC. Therefore, this study is classified as reliable without restrictions