Environmental exposure and ecotoxicological properties of a new generation fluorosurfactant (cC6O4): A comparison with selected legacy perfluoroalkyl acids (PFAA).

Cyclic C6O4 (cC6O4, CAS number 1190931-27-1) is a new generation polyfluorinated alkyl substance (PFAS) used as polymerisation aid in the synthesis of fluoropolymers, produced in Italy since 2011. A review of the properties of cC6O4, focused on environmental distribution and ecotoxicology, was conducted. EQC model was applied, using default environmental scenarios, to estimate environmental distribution and fate. In a situation of static thermodynamic equilibrium in a closed system (level I) cC6O4 distributes mainly to water (97.6%) and in a minor amount to soil (2.3%). In a more realistic scenario (level III), with dynamic condition in an open system, with advection in air and water and with equal emissions in air and water, the major amount of the compound is transported through water advection. Monitoring data, mainly referred to surface and groundwater, are available for water bodies close to the production sites (maximum measured concentration 52 μg/L) as well as for a wider area in the river Po watershed with concentrations generally lower than 1 μg/L. Few values are also available for concentration in biota. Effect data indicate low toxicity on all tested organisms with NOEC values always higher than the maximum concentrations tested (100 mg/L for acute tests). Bioaccumulation potential is also very low. A comparison with selected widely used PFAS with five to eight C atoms indicate that cC6O4 is substantially less dangerous to aquatic organisms. At the time being, an ecological risk for the aquatic ecosystem may be excluded even in directly exposed ecosystems. However, for a complete assessment of the suitability of cC6O4 as substitute of other PFAS (namely PFOA), more comprehensive chronic experiments are necessary, to produce realistic NOECs, as well as higher tier experiments (e.g., mesocosms) capable to provide ecologically relevant endpoints. Moreover, a more accurate evaluation of the environmental persistence would be necessary.