Persistent free radicals in the smoke of common household materials: Biological and clinical implications

The smoke produced from the oxidative pyrolysis of perfluoro polymers: an ESR spin-trapping study

“…Using an apparatus with a single pyrolysis zone, we previously reported that free radicals were not detected in FEP-100 smoke (29)(30)(31). Because of the observation by Williams et al (9) suggesting that toxic products are formed when a furnace remains in contact with the PFP smoke, a dual-pyrolysis apparatus was constructed.…”

“…We find that radicals can be spin trapped from PFP smoke by using either a single-or a dual-pyrolysis apparatus; however, more intense ESR spectra result by using the dual-pyrolysis apparatus. [We believe our original protocol (29) failed to yield any trappable radicals because of incomplete combustion due to the large amount of PTFE and the short heating times used. In our original experiments, 0.10 g of PTFE was heated from 25 to 500 °C in 180 s and pyrolyzed at 525 °C for 100 s. We have found that, at 500 °C, it takes at least 180 s to produce detectable concentrations of spin adducts.]…”

“…The equipment and methods used to measure and analyze ESR spectra of the spin-trapping solutions have been described elsewhere (26,29).…”

Persistent free radicals, heavy metals and PAHs generated in particulate soot emissions and residue ash from controlled combustion of common types of plastic

“…The persistent radical species with g-value 2.0028 is consistent with an organic carbon-centered radical, which remains persistent due to its "trapping" inside a polymeric carbonaceous matrix material. The signal with g-value 2.0035-2.0038 consists of a group of oxygen-centered radical, which has been identified as semiquinone radicals adsorbed in a polymeric matrix [24].…”

Extremely enhanced contaminant decomposition catalyzed by hemin via the coupling of persistent free radicals and ascorbic acid

“…5,6 The importance of this class of reactive intermediate has been duly noted in environmental, chemical and biological systems due to their persistence and radical reactivity. [7][8][9][10] Generally, current research mainly focuses on regarding PFRs as deleterious species that initiate adverse health impacts such as DNA damage or pulmonary dysfunction. 11,12 Despite several reports on the discovery of PFRs as oxidant activators to oxidize organic compounds, 13,14 the positive roles of PFRs have still been poorly considered so far.…”