Chemical, physical, and toxicological characterization of fumes produced by heating tetrafluoroethene homopolymer and its copolymers with hexafluoropropene and perfluoro (propyl vinyl ether)

Seidel, W. C.; Scherer, Kirby V.; Cline, Dwain; Olson, Allan H.; Bonesteel, Jo-Anne; Church, Daniel F.; Nuggehalli, Shamala K.; Pryor, William A.

doi:10.1021/tx00020a017

Cited by 21 publications

(6 citation statements)

References 15 publications

(39 reference statements)

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“…Although these data are consistent with our hypothesis that inhaled ultra ne particles have a signi cantly greater toxic and in®ammatory potential than larger sized particles, it cannot be excluded that the ageing and coagulation of the fresh PTFE fumes for several minutes had altered potential short-lived toxic radicals on the surface of the particles (Pryor et al 1990). Whether the existence of such radicals plays a role in the toxicity of freshly generated polymer fumes is uncertain; earlier studies have shown that fumes generated from di¬erent plastic materials all show high toxicity regardless of the presence or absence of short-lived radicals (Seidel et al . 1991).…”

Section: (B) E® Ect Of Ageing On Ptfe Toxicitysupporting

confidence: 82%

Toxicology of ultrafine particles:in vivostudies

Oberdürster

2000

Philosophical Transactions of the Royal Society of London. Seri

444

123

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Ultra ne particles (less than 100 nm in diameter) are encountered in ambient air and at the workplace. Normal background levels in the urban atmosphere for ultra ne particles are in the range 1{4 £ 10 4 cm ¡ 3 ; however, their mass concentration is normally not greater than 2 m g m ¡ 3 . At the workplace, ultra ne particles occur regularly in metal fumes and polymer fumes, both of which can induce acute in®ammatory responses in the lung upon inhalation. Although ultra ne particles occurring at the workplace are not representative, and, therefore, are not relevant for urban atmospheric particles, their use in toxicological studies can give valuable information on principles of the toxicity of ultra ne particles. Studies in rats using ultra ne polymer fumes of polytetra®uoroethylene (PTFE) (count median diameter ca. 18 nm) showed that (i) they induced very high pulmonary toxicity and lethality in rats after 15 min of inhalation at 50 m g m ¡ 3 ; (ii) ageing of PTFE fumes resulted in agglomeration to larger particles and loss of toxicity; (iii) repeated pre-exposure for very short periods protected against the toxic and lethal e¬ects of a subsequent 15 min exposure; (iv) rapid translocation of PTFE particles occurred to epithelial, interstitial and endothelial sites. Since one characteristic of urban ultra ne particles is their carbonaceous nature, exposure of rats to laboratory-generated ultra ne carbonaceous (elemental, and organic, carbon) particles was carried out at a concentration of ca. 100 m g m ¡ 3 for 6 h. Modulating factors of responses were prior low-dose inhalation of endotoxin in order to mimic early respiratory tract infections, old age (22-month old rats versus 10-week old rats) and ozone co-exposure. Analysis of results showed that (i) ultra ne carbon particles can induce slight in®ammatory responses; (ii) LPS priming and ozone co-exposure increase the responses to ultra ne carbon; (iii) the aged lung is at increased risk for ultra ne particle-induced oxidative stress. Other studies with ultra ne and ne TiO 2 showed that the same mass dose of ultra ne particles has a signi cantly greater in®ammatory potential than ne particles. The increased surface area of ultra ne particles is apparently a most important determinant for their greater biological activity. In addition, the propensity of ultra ne particles to translocate may result in systemic distribution to extrapulmonary tissues.

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Section: (B) E® Ect Of Ageing On Ptfe Toxicitysupporting

confidence: 82%

Toxicology of ultrafine particles:in vivostudies

Oberdürster

2000

Philosophical Transactions of the Royal Society of London. Seri

444

123

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“…The agglomerates from Teflon are likely a result of the formation of Teflon polymer fragments from the pyrolysis of Teflon. Seidel et al (1991) found that nominal 10 4 Dalton Teflon polymer fragments are formed from the pyrolysis of Teflon over the same temperature range as our experiments with Teflon. These fragments apparently grow through nucleation/condensation/coagulation to form nominal 30 nm solidlike spherules.…”

Section: Chemical Basis For Smoke Particle Morphologysupporting

confidence: 75%

Pyrolysis Smoke Generated Under Low-Gravity Conditions

Mulholland

Meyer

Urban

et al. 2015

Aerosol Science and Technology

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A series of smoke experiments were carried out in the Microgravity Science Glovebox on the International Space Station (ISS) Facility to assess the impact of low-gravity conditions on the properties of the smoke aerosol. The smokes were generated by heating five different materials commonly used in space vehicles. This study focuses on the effects of flow and heating temperature for low-gravity conditions on the pyrolysis rate, the smoke plume structure, the smoke yield, the average particle size, and particle structure. Low-gravity conditions allowed a unique opportunity to study the smoke plume for zero external flow without the complication of buoyancy. The diameter of average mass increased on average by a factor of 1.9 and the morphology of the smoke changed from agglomerate with flow to spherical at no flow for one material. The no flow case is an important scenario in spacecraft where smoke could be generated by the overheating of electronic components in confined spaces. From electron microcopy of samples returned to earth, it was found that the smoke can form an agglomerate shape as well as a spherical shape, which had previously been the assumed shape. A possible explanation for the shape of the smoke generated by each material is presented.

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“…The physical conditions in these tests are usually not well defined (as to temperature, contact time, flow rate, oxygen depletion, etc.). In~, the primary low temperature toxic component is a polymer fragment (Waritz and Kwon 1968;Seidel et al 1991). Temperatures at which this is important (below 450°C) and the relatively low degree of polymerization during c-CdF8 pyrolysis suggest that this is not likely to be a problem with C-C4F8.At higher temperatures, PTFE pyrolysis products are very similar to those of C-C4F8, so some relevant qualitative comparisons might be drawn.…”

Section: Toxicitymentioning

confidence: 99%

“…A series of PTFE fire studies (Baker and Kaiser 1991;Seidel et al 1991), was conducted in an attempt to duplicate earlier very high toxicity results (Levin et al 1982). Baker and Seidel concluded that the National Bureau of Standardstoxicity was dueto the formationof toxic particulate under fairly special conditions, namely those in which polymer degradation fumes are heated and reheated in a hot furnace without an actual flame.…”

Section: Descriptive Chemistrymentioning

confidence: 99%

Potential Hazards Relating to Pyrolysis of c-C{sub 4}F{sub 8} in Selected Gaseous Diffusion Plant Operations

Trowbridge¹

1999

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Boolean logic expressions are ollen derived in safety and reliability analysis. Since the values of the operands are rarely exact, accounting for uncertainty with the tightest justifiable bounds is important. Accurate determination of result bounds is difficult when the inputs have "constraints." One example of a constraint is that an uncertain variable that appears multiple times in a Boolean expression must always have the same value, although the value cannot be exactly specified. A solution for this "repeated variable" problem is demonstrated for two Boolean classes. The classes, termed iimctions with "unate" variables (including, but not limited to unate fictions), and "exclusive-or" finctions, frequently appear in Boolean equations for uncertain outcomes portrayed by logic trees (event trees and fault trees). * Sandia is a multiprograrn laboratory operated by Sandia Corporation a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000 ThE report has been reproduced from the best available copy. Reports are available to the publicfrom the followingsource.

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Chemical, physical, and toxicological characterization of fumes produced by heating tetrafluoroethene homopolymer and its copolymers with hexafluoropropene and perfluoro (propyl vinyl ether)

Cited by 21 publications

References 15 publications

Toxicology of ultrafine particles:in vivostudies

Toxicology of ultrafine particles:in vivostudies

Pyrolysis Smoke Generated Under Low-Gravity Conditions

Potential Hazards Relating to Pyrolysis of c-C{sub 4}F{sub 8} in Selected Gaseous Diffusion Plant Operations

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