Reaction mass of 1,1,2,2,3,3,3-heptafluoro-N-(heptafluoropropyl)-N-(pentafluoroethyl)propan-1-amine and 1,1,2,2,3,3,3-heptafluoro-N-(heptafluoropropyl)-N-(trifluoromethyl)propan-1-amine and 1,1,2,2,3,3,3-heptafluoro-N,N-bis(heptafluoropropyl)propan-1-amine

Endpoint summary

Additional information

MTDID 50908 is volatile (vapor pressure, 41 mm Hg at 20 °C) and of low water solubility (range for predominant constituents and impurities, <0.00516 ng/mL to 1.84 ng/mL at 23.6 °C).  A range of Henry's Law constants for predominant constituents and impurities (expressed as the ratio of vapor phase partial pressure over aqueous phase concentration) of 3400 - 4020 atm∙m³/mol, at 22 °C was established by readacross from category members, with more soluble, minor impurities having a somewhat lower value (ca. 1030 atm∙m³/mol at 22 °C) for minor impurities of higher water solubility.  A range of log Kow values of 5.46 - >6.49 at 23 °C was established experimentally for impurities and constituents.  However, it is not expected that MTDID 50908 will have a significant presence in the aquatic compartment, and bioaccumulation in aquatic organisms is not expected.

MTDID 50908 is not expected to partition from the atmosphere to moist soils or surface waters.  MTDID 50908 is manufactured for export; it is not expected to be released to aquatic systems or soils.  Upon direct release of MTDID 50908 to the aquatic compartment, the chemical would be expected to volatilize rapidly.  However, as noted MTDID 50908 release is entirely to the atmosphere.  MTDID 50908 is not expected to partition to aquatic compartments from the atmosphere, therefore no exposure to aquatic organisms is expected.

Bioaccumulation studies are not required at this annual volume, and no studies were done on bioaccumulation of MTDID 50908.  Based on the log Kow range of 5.46 – >6.49, this substance would be considered bioaccumulative in aquatic organisms.  However, substantial bioaccumulation of MTDID 50908 in aquatic organisms is not expected due to lack of exposure in aquatic systems.  MTDID 50908 is expected to reside entirely in the atmospheric compartment, so air breathing organisms were evaluated for bioaccumulation potential.  According to Chapter R.7.10.3.4 of the Technical Guidance (Other indication of bioaccumulation potential):

"For air-breathing organisms, respiratory elimination occurs via lipid-air exchange, and such exchange declines as the octanol-air partition coefficient (Koa) increases, with biomagnification predicted to occur in many mammals at a log Koa above 5. Such biomagnification does not occur if the substance and its metabolites are rapidly eliminated in urine (i.e. have a log Kow  of around 2 or less). Thus the bioaccumulation potential in air-breathing organisms is a function of both log Kow  and log Koa. In contrast, respiratory elimination in non-mammalian aquatic organisms occurs via gill ventilation to water, and this process is known to be inversely related to the log Kow  (hence an increase in log Kow  results in a decrease in the rate of elimination and hence increase in the accumulation potential)."

Log octanol-air partition coefficient (log Koa) values <1.1 were calculated for MTDID 50908 using the relationship:

Koa (unitless) = Kow / Kaw

Where Kow is octanol:water partition coefficient and Kaw is the dimensionless Henry’s Law constant.  Input data were derived from category members. As per Kelly and Gobas (1), chemicals with log Koa < 4 do not biomagnify regardless of the Kow  because of efficient elimination via air exhalation (or, in this case, extremely inefficient absorption via air inhalation).  According to the classification scheme proposed in Chapter R7.10.3.4, MTDID 50908 is a non-polar volatile (high log Kow  and low log Koa), and is not expected to bioaccumulate in air-breathing organisms.  As stated, the potential to accumulate in aquatic organisms is mitigated by the lack of relevance of the aquatic exposure pathway. Therefore, bioaccumulation of MTDID 50908 in terrestrial or aquatic organisms is not expected.

Reference:

1) Kelly, B.C. and F.A.P.C. Gobas.  2003.  An Arctic Terrestrial Food-Chain Bioaccumulation Model for Persistent Organic Pollutants.  Environ. Sci. Technol Vol. 37, No. 13, pp 2966–2974.