Tetrafluoroethylene

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.064 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.64 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.006 mg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

no emission to STP expected

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.33 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

no exposure of sediment expected

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.31 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Any TFE released into the environment is expected to partition almost entirely to atmosphere, where it will quickly react with hydroxyl radicals (°OH), with an atmospheric lifetime of less than 2 days. Subsequent decomposition leads to carbonyl fluoride (COF₂) which is further hydrolysed in the presence of atmospheric water to form hydrogen fluoride (HF) and carbon dioxide (CO₂), the HF being washed out by rain.

TFE does not contribute directly to the greenhouse effect (global warming), but may enhance the formation of tropospheric ozone. TFE is not expected to bioaccumulate. TFE will not absorb significantly to soil and sediment (log Kow = 1.21) .

Aquatic PNECs are derived by applying an appropriate assessment factor to the predicted 96 hr EC50 in algae of 64mg/l, which is the lowest of the short-term toxicity values (fish, Daphnia and algae) obtained from ECOSAR v1.00

The PNEC for sediment is calculated according to the equilibrium partitioning method described in REACH Guidance on information requirements and chemical safety assessment Chapters R.16 (May 2010) and R.10

Ksusp-water is calculated according to equation R16.7

Ksusp-water = Fwater-susp + (Fsoild-susp x Kp susp X RHO solid) /1000 .

Where Kp susp = Foc susp x Koc (Equation R16.6)

Using a koc for TFE of 11.21kg/l

Kp susp = 0.10 x 11.21 = 1.121 l/kg

Using Equation R16.7

K susp-water = 0.9 + (0.1 x 1.121 x 2500) / 1000

K susp-water = 0.9 + 0.2803 = 1.1803

PNECsed for TFE is calculated according to equation R10.2 of Chapter 10.

PNEC sed = Ksusp-water x PNEC water x 1000 / RHO susp

PNEC sed = 1.1803 x 0.064 x 1000 /1150

PNEC sed for TFE = 0.0656 mg/kg (of wet sediment)

This PNEC value is converted to the value for dry sediment by dividing by the fraction of solid in sediment (0.2) to give:

PNEC sed = 0.0656 / 0.2 = 0.33 mg/kg (of dry sediment)

The PNEC for soil is calculated according to the equilibrium partitioning method described in REACH Guidance on information requirements and chemical safety assessment Chapters R.16 (May 2010) and R.10.

Ksoil-water is calculated according to equation R16.7

Ksoil-water = Fair-soil x.Kair-water +Fwater-soil + (Fsoild-soil x Kp soil X RHO solid) /1000 .

Where Kp soil = Foc soil x Koc (Equation R16.6)

Using a Koc for TFE of 11.21 l/kg

Kp soil = 0.02 x 11.21 = 0.2242 l/kg

And Kair-water = Henry (TFE) Pa.m3.mol-1/R x 285K

Kair-water = 92109 / 8.314 x 285 = 38.87

Using Equation R16.7

K soil-water = 0.2 x 38.87 + 0.2 + (0.6 x 0.2241 x 2500) / 1000

K soil-water = 7.77 + 0.2 + 0.34 = 8.31

PNECsoil for TFE is calculated according to equation R10.5 of Chapter 10.

PNEC soil = Ksoil-water x PNEC water x 1000 / RHO soil

PNEC soil = 8.31 x 0.064 x 1000 /1700

PNEC soil for TFE = 0.31mg/kg

Conclusion on classification

Classification under DSD and GHS

The predicted toxic concentrations to aquatic organisms, predicted by ECOSAR v1.00a, are unlikely to be achieved since TFE is a gas and any environmental discharges are likely to partition to atmosphere. Therefore, it can be assumed that TFE will not be toxic in the aquatic environment. The atmospheric lifetime is < 2 days, and thus TFE is not persistent. The substance does not need to be classified as Dangerous for the Environment according to EU Directive 67/548/EEC and EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) N0. 1272/2008.

Preliminary PBT assessment

An assessment of the PBT status of tetrafluoroethylene (TFE) has been made using all available data. The information available suggests that TFE does not meet the PBT screening criteria as outlined in Directive 2006/121/EC (see Appendix A for the criteria).

Persistence

As a highly fluorinated molecule, TFE is not anticipated to be readily biodegradable in aquatic media; however, since it is a gas of low solubility TFE will readily partition to atmosphere and thus will not be persistent in the aquatic environment.

Bioaccumulation

No bioconcentration test is available. However, as the log Kow is 1.21 bioaccumulation is not expected. TFE is therefore considered not bioaccumulative.

Toxicity

No aquatic toxicity data exist for TFE. Direct and indirect exposure of the aquatic compartment to TFE is not expected. Since it is a gas of low solubility any water-borne TFE will rapidly partition to air, and thus impact on aquatic life is expected to be minimal. ECOSAR predictions give a further indication that TFE would be of low toxicity to aquatic life, the estimated acute effect concentrations being much higher than the screening criterion of 0.1 mg/l. It can therefore be expected that TFE will not be toxic towards aquatic organisms. Because TFE will rapidly partition to air it will not persist in aqueous media and chronic effect concentrations are likely to be much higher then the defined criterion of 0.01 mg/l.

TFE is of relatively low acute toxicity. However it can be considered to be classified as being a CMR, since tests in experimental animals have shown it to be a carcinogen. Though tumour formation is not through a genotoxic mechanism, classification as an EU Category 2 Carcinogen is considered warranted and TFE is thus assigned as being toxic.

The overall conclusions, based on the present available data, of the preliminary PBT assessment are that the (screening) criteria for PBT/vPvB are not met for TFE and that further testing in the scope of the final PBT assessment is not considered to be required.