Uptake of cyclic C6O4 in maize and tomato: Results from a greenhouse study.

Cyclic C6O4 (cC6O4, CAS number 1190931-27-1) is a perfluoralkyl ether used as a polymerization aid in the synthesis of fluoropolymers and produced since 2011 as substitute of PFOA. This work reports the first data on bioaccumulation of cC6O4 on terrestrial plants (maize and tomato). In general, the observed accumulation and translocation of cC6O4 in plants is low or negligible. For maize a bioconcentration factor (BCFdw/dw) of about 39 was observed in the root compartment and much lower (BCFdw/dw = 12) in the aboveground tissues. In tomato the observed BCFs are substantially lower, with a maximum of 2.5 in leaves. The differences observed between the uptake and distribution of cC6O4 in maize and tomato plants are probably due to differences in plant physiology (but also in the experimental design of the tests). Maize plants grown at different concentrations in this study did not show relevant differences in term of biomass and growth, while tomato plants exposed to cC6O4 were subject to a delay in the ripening of the fruits (and relative biomass). The overall results are discussed in comparison with literature data available for legacy PFASs but the comparison is difficult due to differences in the experimental design. It is relevant to note that the concentrations tested in this study are significantly higher than expected environmental concentrations.

Toxicity and bioaccumulation of the fluorosurfactant cC6O4 in the earthworm Eisenia foetida (Savigny, 1826).

Cyclic C6O4 (cC6O4, CAS number 1190931-27-1) is a perfluoralkyl ether PFAS used as a polymerization aid in the synthesis of fluoropolymers and produced in Italy since 2011 as substitute of PFOA. To date, available ecotoxicological information on cC6O4 is related to regulatory requirements and limited to data on aquatic organisms, while the information on the effects for terrestrial organisms is completely lacking. This work reports the first ecotoxicological data of cC6O4 on terrestrial invertebrates: short- and long-term toxicity of cC6O4 on Eisenia foetida (Savigny, 1826), exposed to spiked soil under laboratory conditions, was investigated evaluating the earthworm survival and growth (observed after 7, 14 and 28 days of exposure), and reproduction (observed after an exposure period of 56 days). Furthermore, also bioaccumulation was investigated (28 days of exposure); overall results are discussed in comparison with literature data available for legacy PFAS. cC6O4 did not cause significant mortality on earthworms, for any of the tested concentrations and exposure periods (NOEC: > 1390 mg/kg d.w.), while the reproduction (measured as juveniles production) appears to be a more sensitive endpoint (EC50: 10.4 mg/kg d.w., EC10: 0.8 mg/kg d.w.). The observed adverse effects occur at levels significantly higher than realistic soil concentrations and cC6O4 appears to be less toxic than PFOA and PFOS. As for bioaccumulation, the results indicate a negligible bioaccumulation potential of cC6O4, whose Biota-Soil Bioaccumulation Factors (BSAF) are significantly lower than all other considered PFAS.

The validation of converting pyrite ash-contaminated soil into End-of-Waste by the High-Performance Solidification/Stabilization process application.

One of the major challenges to establishing more sustainable management strategies than landfill disposal of metals-contaminated soils is the lack of End-of-Waste (EoW) criteria defined at the European and national levels. Another limitation stems from the scarcity of information on industrial-scale applications of treatment technologies able to obtain safe and reusable materials from such contaminated waste. In this context, the High-Performance Solidification/Stabilization process was applied for the full-scale remediation of pyrite ash-contaminated soil (ca. 24 000 m3 ), and a dedicated sampling and analytical protocol was developed and implemented to verify if the treated material obtained complied with the general EoW criteria established by article 6 of the Waste Framework Directive 2008/98/EC. The results of the leaching, ecotoxicological, and mechanical tests carried out on representative samples of the treated soil showed that this material (ca. 19 000 m3 ) could be classified as EoW and thus was deemed reusable both in-situ as filler for the excavation and ex-situ as road construction material. These results improve the knowledge of the performance of a state-of-the-art technique for the treatment of metals-contaminated soil. Furthermore, the developed monitoring plan can support future assessments on the compliance of materials obtained from contaminated soil with the general EoW criteria. Integr Environ Assess Manag 2023;19:961-969. © 2022 SETAC.