Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

 FC-770 is a mixture of perfluorinated morpholines.  It is a liquid at room temperature with a vapor pressure of 6.7 kPa at 20°C.  FC-770 water solubility is 66.2 µg/L at 23 °C.  Its measured Henry’s law constant (expressed as the ratio of vapor phase partial pressure of FC-770 over aqueous phase concentration) is 1030 atm∙m³/mol at 22 °C. The free energy of hydration (the energy requirement for dissolving a substance from the gas phase into water) is 26 kJ/mol and is an endothermic process. The reverse process, volatilization, is highly favored by comparison due to system thermodynamics. Releases of FC-770 are expected to be to the atmosphere based upon its intended uses.  Fugitive emissions may occur at transfer points.  During routine use, there is no anticipated release to water or wastewater in the EU.  The high vapor pressure, high hydrophobicity, and thermodynamics of gas solubility would combine to move FC-770 from the terrestrial and aquatic compartments into the atmosphere. Once in the atmospheric compartment, this compound will not partition to terrestrial or aquatic compartments based on the same properties. Therefore, this compound will remain in the atmosphere if released from its applications in closed systems.  The molecule contains no hydrolysable groups and is not biodegradable.  Degradation in the environment is expected to be by direct photolysis in the upper atmosphere.  An additional pathway may be indirect photolysis by singlet atomic oxygen, O(¹D), in the stratosphere. An overall lifetime in the range of 1600-4000 years is expected by these processes. Direct photolysis is an energetic process that results in formation of radical species. These are expected to degrade very quickly once formed. The ultimate degradation products are hydrofluoric acid (HF, CAS# 7664-39-3), carbon dioxide and oxides of nitrogen.  These materials are miscible in water and are completely ionized in rainwater. They are expected to undergo wet deposition with no further significant transformation upon return to the troposphere.

 

As FC-770 is a highly fluorinated substance, global warming and ozone depletion potentials may be of interest.  USEPA states flatly that hydrofluorocarbons 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(1).  F* radicals are rapidly and irreversibly removed from the atmosphere after quenching as HF.  Therefore, neither FC-770 nor any of its photodegradation products contribute to ozone depletion. Global warming potential depends on three factors: absorption of infrared radiation, area of the spectrum the absorption occurs and lifetime of the material in the atmosphere.  FC-770 has an estimated GWP of 11,000 over a 100-year integrated time horizon.

 

An evaluation of its fate in water or soil concludes that FC-770 is rapidly removed by volatilization, and it will not partition into water or soil from the atmosphere. Therefore this substance is non-persistent in the aquatic and terrestrial environments and is very persistent only in the atmosphere and is subject to long-range transport. Due to mixing in the atmosphere and lack of partitioning out of the atmosphere, concentrations in the biosphere will be negligible and thus widespread exposure to FC-770 will not occur in aquatic or terrestrial systems. This prediction is corroborated by Level III Mackay modeling in NewEQC.

 

FC-770 is a member of the Perfluorinated Organic Chemicals, C5-C18 category, but is used almost entirely as a source substance for readacross. In the interest of simplifying the technical dossier and registration, FC-770 is being submitted as an individual substance. Please see IUCLID section 13 for a full matrix of data for members of the Perfluorinated Organic Chemicals C5-C18 category.

 

              References

 

1)   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.