Hexafluoropropene, oxidized, oligomers, reduced, fluorinated

Endpoint summary

Additional information

No bioaccumulation studies are available for Galden LMW.

Technical difficulties related to bioaccumulation testing

 

Taking into account the physico-chemical properties of Galden LMW, a bioaccumulation test in aquatic species is not deemed feasible. The substance has a low water solubility (0,47 mg/L) in combination with a high volatility (VP = 15-29 kPa) and a high Henry’s Law constant (H = 1.4 - 2.1 x 10E7). Therefore, a stable concentration of the test substance in water is very difficult to obtain due to volatilization of the test substance from the system.

 

Practical experience with the test substance confirms that difficulties will indeed arise when generating a stable aquatic concentration of Galden LMW.This has been confirmed during the ecotoxicological tests where the preparation of the test media was deemed to be a delicate step with very little success to reach the solubility limit in pure water. For instance, in the short-term toxicity test on Daphnia (semi-static exposure, closed system) performed in 2015 at the best it was possible to reach 0.2 mg/L in the test medium. However this concentration decreased drastically during the first 24 hours, proving the high volatility potential. The same difficulties in generating and keeping a stable aquatic concentration of Galden LMW in water have been encountered in all the ecotoxicological tests.

 

As a consequence, the bioaccumulation test would not lead to a reliable result as no stable concentration could be reached in such trials. The fish dietary test is also not deemed feasible. The same difficulties are also expected for the spiking of food: the high volatility of the substance would not allow it to be significantly adsorbed on the food.

Exposure considerations 

Furthermore, a bioaccumulation test in aquatic species is not deemed required. As stipulated in column 2 of Annex IX, section 9.3.2, bioaccumulation testing does not need to be conducted if direct and indirect exposure of the aquatic compartment is unlikely, or if the substance has a low potential to cross biological membranes.

A justification for the exclusion of direct and indirect exposure of the water phase can be found in the environmental fate modeling and exposure assessment performed in the dossier, and a description of the manufacturing and uses is given in the attached document to the data waiving. From these data, it is clear that:

1. The uses described for Galden LMW will not lead to direct exposure of the water compartment, and

2. Galden LMW will mainly partition into the air compartment, and distribution into the water phase is expected to be negligible.

 

As a consequence, an adaptation of the Annex IX requirement for bioaccumulation testing in aqueous species is considered justified in accordance with the information provided in Column 2 of Annex IX 9.3.2.

Indirect exposure of the aquatic compartment to Galden LMW

Indirect exposure to water is not to be expected, as the substance will not partition into water due to its high vapour pressure, high Henry’s Law Constant and its low solubility in water. As a result the substance can neither be persistent nor bio accumulative in water by lack of exposure in the water phase.

Bioaccumulation in air-breathing species

 

It is to be noted that, even if bioaccumulation in aquatic species is not deemed relevant, bioaccumulation in air-breathing species could still be relevant.

 

Terrestrial organisms can typically take up, and possibly accumulate, contaminants from the diet and via inhalation. Elimination of contaminants or their metabolites can occur via respiration to the air, via excretion in the urine, or via fecal excretion. The tendency of a substance to be eliminated via respired air was found to correlate with its Log Koa, the octanol-air partition coefficient (Kelly, 2007; Kelly, 2003; Gobas 2003). Screening for bioaccumulation potential in non-aquatic organisms therefore can be done based on both the Kow and the Koa value (Gottardo, 2014). Kelly and Gobas demonstrated that substances with a log Kow of approx. > 2 and a log Koa > 5 can biomagnify. Substances with a low Koa (i.e. log Koa between 1 and approx. 5) typically have a BMF <1. For these substances, respiration is the main route of elimination.

 

Galden LMW has a measured log Koa of 0.87, and therefore is not expected to bioaccumulate in air-breathing organisms due to a quick elimination of the substance via respiration to air.

 

References

 

Gottardo, S.; Hartmann, N.B.; Sokull-Klüttgen, B. (European Commission – Joint Reserch Centre). Assessment of bioaccumulation and toxicity with non-aquatic organisms. ENTR-ENV PBT Workshop, Brussels, 17 December2014.

 

Gobas, F.A.P.C; Kelly, B.C.; Arnot, J.A. Quantitative Structure Activity Relationships for Predicting the Bioaccumulation of POPs in Terrestrial Food-Webs. QSAR Comb. Sci.2003, 22, p.329-336.

 

Kelly, B.C.; Gobas, F.A.P.C. An Arctic Terrestrial Food-Chain Bioaccumulation Model for Persistent Organic Pollutants. Environ. Sci. Technol.2003, 37, p. 2966-2974.

 

Kelly, B.C.; Ikonomou, M.G.; Blair, J.D.; Morin, A.E.; Gobas, F.A.P.C. Food Web-Specific Biomagnification of Persistent Organic Pollutants. Science,2007, 317, 236-239.