Perfluorinated Compounds

The novel PFOS alternatives, 6:2 chlorinated polyfluorinated ether sulfonate (F-53B) and sodium p-perfluorous nonenoxybenzenesulfonate (OBS), are emerging in the Chinese market, but little is known about their ecological risks. In this study, zebrafish embryos were exposed to PFOS, F-53B, and OBS to evaluate their bioconcentration and acute metabolic consequences. Per- and polyfluoroalkyl substances (PFASs) accumulated in larvae in the order of F-53B > PFOS > OBS, with the bioconcentration factors ranging from 20 to 357. Exposure to F-53B and PFOS, but not OBS, increased energy expenditure, and reduced feed intake in a concentration-dependent manner and the expression of genes involved in metabolic pathways at the transcriptional and translational levels. Molecular docking revealed that the binding affinities of PFASs to glucokinase were decreased in the following order: F-53B > PFOS > OBS. Finally, the results of Point of Departure (PoD) indicate that metabolic end points at the molecular and organismal level are most sensitive to F-53B followed by PFOS and OBS. Collectively, F-53B has the highest bioconcentration potential and the strongest metabolism-disrupting effects, followed by PFOS and OBS. Our findings have important implications for the assessment of early developmental metabolic effects of PFOS alternatives F-53B and OBS in wildlife and humans.

Fluorinated organic chemicals have a wide variety of industrial and consumer applications. For long time perfluorooctane sulfonate and perfluorooctanoic acid have been used as precursors for manufacture of such chemicals. However, these C 8 chain compounds have been demonstrated to be toxic, persistent, and bioaccumulative, thus inducing their phase-out. Currently, C 6 telomer based fluorocarbon surfactants are considered better alternatives to C 8 products because of their low bioaccumulability. But, their high persistency suggests that in the near future their concentrations will increase in the environment and in industrial waste. Being a solid state non-thermal technology, mechanochemical treatment is a good candidate for the destruction of emerging C 6 fluorotelomers in solid waste. In the present study, 6:2 fluorotelomer sulfonate is effectively destroyed (~100%) in rapid manner (<1 h) by high energy ball milling with KOH. Stoichiometric fluoride formation confirms its entire mineralization, assuring that no toxic by-products are generated. Reaction mechanism and kinetics indicate that effective mineralization of the perfluorinated moiety is obtained thanks to a rapid CF 2 " flake-off " process through radical mechanism.

Perfluorinated chemicals (PFCs) are attracting increasing concern due to their chemical stability and toxicity, which make them classifiable as persistent organic pollutants. However, such compounds are employed for the manufacture of many industrial and consumer products, hence their substitution is not possible in the near future. Suitable technologies for PFCs environmentally sound management are necessary. High energy ball milling with KOH has been proved to obtain PFCs safe destruction, but with excessive reagent. In the present study, a Waste-to-Materials solution is proposed: PFCs are co-milled with stoichiometric amounts of La2O3 and thus are fully converted into LaOF, a noteworthy luminescent material with many potential industrial applications. Reaction mechanism is also investigated: Ball milling process activates La2O3; this latter provokes oxidation to CO2 and carbonization of PFCs; fluorides are incorporated into the La2O3’s lattice to form the oxyfluoride. Interestingly, kinetic analysis suggests that the mechanical activation of La2O3 might follow a zeroth-order reaction rate.

Nilsen AJ, Landin MA, Haug KH, Fonnum F, Berger U, Osmundsen H. Comparative hepatic gene expression profiling of rats treated with 1H,1H,2H,2H-heptadecafluorodecan-1-ol or with pentadecafluorooctanoic acid. Pentadecafluorooctanoic acid is an established peroxisome proliferator. Little is known about effects of treatment with 1H,1H,2H,2H-heptadecafluorodecan-1-ol, which is metabolized to pentadecafluorooctanoic acid. We compared effects of various dosages (3, 10, or 25 mg/kg body wt) of each of these compounds on hepatic gene expression in rats with microarrays. Microarray data were validated by real-time RT-PCR. Expression data were also correlated with hepatic activities of selected enzymes and with hepatic levels of pentadecafluorooctanoic acid and 1H,1H,2H,2H-heptadecafluorodecan-1-ol. Pentadecafluorooctanoic acid caused the more powerful change in gene expression, in terms of both number of genes affected and extent of change in expression. Across the dosages used pentadecafluorooctanoic acid and 1H,1H,2H,2H-heptadecafluorodecan-1-ol caused significant (P Յ 0.05) changes in expression for 441 and 105 genes, respectively. With 1H,1H,2H,2H-heptadecafluorodecan-1-ol ϳ38% of the 105 genes exhibited decreased expression with a dose of 25 mg/kg body wt, these genes also appearing less responsive to treatment at the lower dosages. Bioinformatic analysis suggested that these genes are associated with regulatory functions. With pentadecafluorooctanoic acid, increasing dosage up to 10 mg/kg body wt brought about progressive increase in expression of affected genes. Pathways analysis suggested similar effects of the two compounds on lipid and amino acid metabolism. Marked differences were also found, particularly with respect to effects on genes related to oxidative phosphorylation, oxidative metabolism, free radical scavenging, xenobiotic metabolism, and complement and coagulation cascades.

19F NMR spectroscopy was used to determine quantitatively the organ distribution and organ retention time in rats of the mixed fluorocarbon–hydrocarbon dowel molecule C6F13CH = CHC10H21 (F6H10E), which stabilizes highly concentrated injectable fluorocarbon emulsions destined for in vivo oxygen transport and delivery. The only fluorine resonances detected in the 19F NMR spectra of the organs analyzed were those of the F6H10E dowel itself, indicating that metabolites, if present, have very low concentrations (<10−4M, limit of our assay). The F6H10E content in the liver peaked 1 day after administration (7 days for the spleen). At a dose of 3.6 g/kg body weight, the half-life of F6H10E in the liver was 25 ± 5 days.

Our environment has been affected by increasing concentration of organic and inorganic pollutants from anthropogenic sources. Perfluorinated compounds are an important source of pollution, and they are major risks for the aquatic ecosystems. Perfluorooctane sulfonate (PFOS) and Perfluorooctane sulfonyl fluoride (POSF) are both industrially synthesized perfluorinated chemicals, and they produced in substantial amounts. They are found widely in surface water and aquatic sediments. In this study, the comparative embryotoxicity of increasing concentrations of PFOS (five concentrations ranging from 0.5 to 10 mg/L) and POSF (five concentrations ranging from 0.5 to 10 mg/L) were examined on embryos of the sea urchin, Paracentrotus lividus. Results were evaluated by observing: larval malformations, developmental arrest and embryonic/larval mortality. The results indicated that, low concentrations of these chemicals generally caused malformations in the skeletal system. It was observed that high concentrations (10 mg-PFOS/L, 10mg-POSF/L) inhibited the growth of embryos in the early life stages. As a result, POSF was more toxic than PFOS (EC 50 : 1.795 mg/L) on sea urchin embryo as the EC 50 is 1.074 mg/L and also both of the chemicals were harmful on the embryonic development of sea urchin in the sense of whole embryo and cellular level. In conclusion, PFOS and POSF present a major risk to the normal development of P. lividus in the environment, so that it has ecological importance due to the hazard at a population level considering the cumulative effects of other environmental pollutants.

High yield monomeric tetrafluoroethylene may be recovered from polytetrafluoroethylene and polytetrafluoroethylene composites by pyrolyzing the polymer in the presence o high temperature steam. The steam acts as a condensable carrier gas for low molecular weight pyrolysis products and should be present in an amount such that the ratio of steam to pyrolysis products is at least one to one. The steam also acts as a means for heating the polymer to the necessary decomposition temperatures.  This method is environmentally effective for the recycle of polymers.