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EC number: 473-390-7
CAS number: -
FC-770 distribution was examined using the NewEQC v.1.01a Level III
Mackay model. This model incorporates advances in the science of
chemical partitioning and reactivity as compared to the original EQC
fugacity model (note: EQC is currently adapted for use in
EpiSuite/Epiweb v 4.1). The NewEQC model specifically includes improved
treatment of input partitioning and reactivity data, temperature
dependence, and sensitivity /uncertainty analysis. In addition to the
variables which EpiSuite's adaptation of EQC allows to be entered
(Henry's Law constant, melting point, boiling point, water solubility,
vapor pressure, and Log Kow), New EQC allows the user to enter Log Kaw,
Log Koc, BCF, the aerosol-air partition coefficient, the soil/water
partition coefficient, and the benthic- and suspended-sediment/water
partition coefficients. Where these values have not been directly
measured, specific default calculations are applied. Use of this model
is most appropriate when applied to chemicals of unusual properties such
as FC-770. The most useful results provided by the model are the
percentage distribution of chemical mass between media or phases, and
the residence times for reaction, advection and overall removal. The
result, for FC-770< is a marked decrease in the dependence on release
patterns for NewEQC as compared to EpiSuite's adaptation. The NewEQC
model is commonly accepted and has been validated in the literature
(Hughes, L., Mackay, D., Powell, D. E., and Kim, J. 2012. An updated
state of the science EQC model for evaluating chemical fate in the
environment: Application to D5 (decamethylcyclopentasiloxane).
Chemosphere 87(2): 118-124).
In keeping with the uses defined for FC-770, the entire volume is
modeled as being released exclusively to the atmospheric compartment, at
a rate of 250 tonnes per year (i.e., 2.5-times larger than the maximum
annual volume for this volume band). The model environment has an area
of 10,000,000 hectares, which is 2.5-times larger than the
4,000,000-hectare Standard Region normally considered during exposure
assessment modeling with EUSES software. The atmospheric residence time
of the model environment is 100 hours. When compared to EpiSuite, use
of the NewEQC Level III Mackay fugacity model results in significant
changes in the distribution pattern upon release to air (the only
release of FC-770). EpiSuite modeling gives 90.3% to air, 0.2% to water,
8.9% to soil, and 0.6% to sediment. In contrast, New EQC gives 99.996 %
to air, 5.1 x 10-6 % to water, 3.8 x 10-3 % to soil, and 1.8 x 10-5 % to
sediment. It should be noted that the volume fraction and default
densities of these compartments, as well as default mass transfer
coefficients, were not modified between EpiSuite's adaptation of EQC and
NewEQC. Expressed in terms of absolute loadings, all compartments
showed predicted concentrations in the part-per-trillion range or less.
The model showed that the overwhelming majority of FC-770 remains in
the atmospheric compartment on a mass basis (Table 2).
Table 2, predicted distribution of FC-770 in the modeled
Amount in compartment (kg)
Concentration in compartment (g/L except as indicated)
Percent of total in compartment
Fish (wet weight)
It is important to note in Table 2 that most (87%) FC-770 in the soil
compartment is in air-filled pore spaces, rather than sorbed to solids
or dissolved in pore water.
Essentially no net transport from air to soil or from air to water
occurs based on relative intermedia transportation rates. The
driving factor in the distribution model is advective transport out of
the model area’s atmospheric compartment. Removal
by this mechanism is essentially equal to the release rate into
the atmospheric compartment. The residence time of 100 hours leads to
far faster rates of removal by transport than either reaction or
transfer between compartments (Table 3).
Table 3, Details on loss and distribution processes
Loss Rate (kg/h)
Air to Water
Air to Soil
Water to Air
Water to Sediment
Soil to Air
Soil to Water
Sediment to Water
The intermedia transport rates depend on concentration in the relevant
compartments. The model also generates a more general
set of intermedia transport half times (Table 4), which depend on
chemical and compartment characteristics but not concentration. It
is evident from the half-times that only extreme concentration gradients
favoring the atmospheric compartment allow transfer of meaningful
amounts of FC-770 to soil or water.
Table 4, Intermedia transport half-times
Half-time (days unless otherwise listed)
Transfer time ratio
Air : Water
Air : Soil
Water : Sediment
Based on the results of this distribution modeling, which places 250
tonnes per year of FC-770 into an area 2.5 times larger than the
Standard Region for exposure assessment modeling, FC-770 will not
distribute meaningfully into the terrestrial or aquatic compartments.
The model calculated that 99.996% of FC-72 is distributed to the air.
The air to water half-life was modeled to be 461,000 years while the
water to air half-life was 12.7 days; the air to soil half-life was 1610
days while the soil to air half-life was calculated to be 1.59 hours;
the water to sediment half-life was 81.4 hours while the sediment to
water half-life was calculated to be 1310 days.
FC-770 distribution in the environment was modeled using a Level III
fugacity model within the New Equilibrium Criterion model (NewEQC)
v.1.01 (Trent University, Peterborough, ON, Canada). Substance
properties were entered as per data in this dossier. A total emission
rate of 250 kg/year of FC-770 was directed entirely (100%) to air based
on uses described in this dossier. The predominant fraction (99.996%)
was modeled as remaining present in the gas phase of the air
compartment. The calculated intermedia distribution half-time from the
soil compartment to the air compartment was 1.59 hours while the reverse
process had a half-time of 1610 days. The calculated half-time for water
to air was 12.7 days while the half-time for air to water was 461,000
years. FC-770 will not distribute meaningfully into the terrestrial or
Distribution modeling was done using a well-accepted model. It is
considered reliable with restrictions.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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