Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

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Additional information

PPVE is used as a monomer in polymer manufacture. PPVE is a liquid at room temperature with a vapor pressure of 410 mm Hg at 20°C. The water solubility is 1.8 mg/L at 22.3 °C. The measured Henry’s Law constant (HLC) is 78.3 atm·m³/mole. The vapor pressure, water solubility and high Henry’s law constant combine to move PPVE from any terrestrial compartment into the atmosphere. Evaporation of PPVE from surfaces is rapid. Fugacity modeling indicates that distribution from soil to air dominates over all other processes, and therefore that release to soils would result in rapid volatilization to the atmospheric compartment. Given identified uses (manufacturing and polymerization) and technical processes during use, essentially all releases are to the atmospheric compartment. Assuming 100% release to the atmospheric compartment, 99.996% of substance remains in the gas phase of the air compartment, with 0.0036% in gas-filled pore paces, and 0.00020% sorbed to soil solids. Therefore, this compound will remain in the atmosphere when released from industrial applications.  Degradation in the environment is by indirect photolysis, with a half-life of approximately 4.8 days. The pathway for decay (1) is expected to be addition of hydroxyl radical to the vinylic group followed by decay of the radical adduct. The ultimate degradation products are expected to be perfluoropropionic acid (PFPA) and hydrofluoric acid (HF). These acids are miscible in water and are completely ionized in rainwater. They are expected to undergo wet deposition with no further significant transformation. Degradation is expected to take place after atmospheric mixing, and production of PFPA would occur over a distributed area leading to trace levels in terrestrial and aquatic systems.

USEPA states flatly that fluorocarbons do not deplete ozone because they lack chlorine or bromine. Fluorine radicals do not contribute to ozone depletion because of fast quenching of F* by water or hydrogen donors, slow reaction of FO* radicals with oxygen, and obligate reformation of F* in the pathway (3). F* radicals are rapidly and irreversibly removed from the atmosphere after quenching as HF. Therefore, neither PPVE nor any of its acidic photodegradation products contribute to ozone depletion.

PPVE is not expected to partition to moist soils or surface waters. Upon accidental, direct release to the aquatic compartment, the chemical is expected to volatilize rapidly. In closed-bottle (OECD301D) assays, ≤7% biodegradation was observed. PPVE has a measured log n-octanol:water partition coefficient of 4.0 and is expected to have little potential to bioaccumulate. The calculated log Koa of PPVE is 0.46. This log Koa value indicates that PPVE has a low potential to partition from air to the lipid rich tissues of air-breathing organisms. Given its extremely short half-life due to volatilization, it would not remain in aquatic environments or organisms for a sufficient time to allow partitioning into lipid tissues or to permit meaningful testing of bioconcentration.

Distribution of PFPA and HF in the environment is driven by the fact that these acids are completely ionized at environmental pH values, are miscible in water, and are not likely to bind with organic matter based on low Koc values and low log Kow values. PFPA and HF will be associated with the aqueous phase of any environment where they are released, and will be highly mobile in soils. PFPA and HF that have deposited in aquatic compartments are expected to remain in the aquatic compartment. The registrant has assessed PFPA in ready biodegradation tests and demonstrated that essentially no biodegradation occurs. The registrant has completed a bioconcentration study of PFPA in carp. The BCF at steady state was found to be 1.2 - ≤4.8. PFPA is not subject to bioaccumulation in aquatic organisms.

HF is an inorganic mineral acid. It is not subject to biodegradation.

References:

1) D. Amedro, L. Vereecken, J.N. Crowley. 2015. Kinetics and mechanism of the reaction of perfluoro propyl vinyl ether (PPVE, C3F7OCF=CF2) with OH: assessment of its fate in the atmosphere. Phys. Chem. Chem. Phys. Vol. 17, pp. 18558–18566.

2) A.J. Colussi, M.A. Crela. 1994. Rate of the reaction between oxygen monofluoride and ozone. Implications for the atmospheric role of fluorine. Chem. Phys. Lett. Vol. 229, pp. 134-138.