The Inhalation Toxicity of Pyrolysis Products of Polytetrafluoroethylene Heated Below 500 Degrees Centigrade

Waritz, Richard S.; Kwon, B. K.

doi:10.1080/00028896809342976

Cited by 48 publications

(27 citation statements)

References 7 publications

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“…Preliminary attempts to adsorb PTFE gas-phase constituents onto ultra ne carbon particles did not result in acute pulmonary, in®ammatory responses. Earlier studies have also found that gas-phase compounds of PTFE fumes do not cause the high toxicity when generated below 500¯C (Waritz & Kwon 1968). However, additional studies may be needed to con rm that gas-phase compounds do not play a role in PTFE fume toxicity.…”

Section: (D ) Particle Versus Gas Phase Toxicity Of Ptfe Fumesmentioning

confidence: 93%

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: (D ) Particle Versus Gas Phase Toxicity Of Ptfe Fumesmentioning

confidence: 93%

Toxicology of ultrafine particles:in vivostudies

Oberdürster

2000

Philosophical Transactions of the Royal Society of London. Seri

444

123

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“…The smoke from the FPUF was yellow, dense, and particle-rich within seconds of heating; wispy, whitish, and particle-poor by 3-4 min; and inapparent by 30 Macrophages recovered from exposed mice were markedly altered (Fig. 3a-e).…”

Section: Resultsmentioning

confidence: 99%

“…1) and Protocol. Pathogen-free CFW male mice, 7-9 wk old and weighing [25][26][27][28][29][30][31][32] Thus, the total fluid-lung contact time was 6-10 sec. Total cell counts and total protein determinations on the recovered fluid were performed (24).…”

Section: Methodsmentioning

confidence: 99%

“…BAL lends itself to making assessments of the relative roles of particulates and gases in the injury mechanisms (12,20). While filter removal of smoke particles reduced the toxicity of the smoke in other models (6,20,30), filters also absorb other smoke constituents. In our model, the particles appear in the smoke within seconds of heating and are undetected after a few more minutes of heating; i.e., there are distinct periods of particle-rich smoke and particle-poor smoke, to which mice can be exposed separately, thus eliminating the need for filters.…”

Section: Effects Of Exposures To Fpuf Smokementioning

confidence: 99%

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Lung Injury after Experimental Smoke Inhalation: Particle-Associated Changes in Alveolar Macrophages

1993

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“…These fluids are relatively inert within these systems, i.e., they do not corrode the metals used in these systems, and they are "friendly" to the atmospheric ozone layer. NASA has identified that some of these fluorocarbon fluids may be suitable thermal PFiB was initially identified as the cause of "Teflon flu" which is a highly fatal illness attributable to inhalation of Teflon decomposition products 6 and has an acceptable exposure limit of 10 parts per billion 7 . Subsequent studies on PFiB have shown severe pulmonary injuries from short exposures to "high" concentrations that may go undetected immediately after the exposure.…”

mentioning

confidence: 99%

Chemical Characterization and Thermal Stressing Studies of Perfluorohexane Fluids for Space-Based Applications

Arnold

Hartman

McQuillen

2007

Journal of Spacecraft and Rockets

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Perfluorohexane (PFH), C 6 F 14 , is a perfluorocarbon fluid. Several PFH fluids with different isomer concentrations were evaluated for use in an upcoming NASA space experiment. Samples tested included two commercially obtained high-purity n-perfluorohexane (n-PFH) fluids and a technical grade mixture of C 6 F 14 branched and linear isomers (FC-72 ). These fluids were evaluated for exact chemical composition, impurity purity and high temperature degradation behavior (pyrolysis). Our investigation involved simulated thermal stressing studies of PFH fluids under conditions likely to occur in the event of an atmospheric breach within the International Space Station (ISS) and subsequent exposure of the vapors to the high temperature and catalyst present in its Trace Contaminant Control Subsystem (TCCS). Exposure to temperatures in the temperature range of 200-450°C in an inert or oxidizing atmosphere, with and without the presence of catalyst was investigated. The most aggressive conditions studied were exposure of PFH vapors to 450°C in air and in the presence of TCCS (palladium) catalyst. Gas chromatography-mass spectrometry (GC-MS) and gas chromatography (GC) analyses were conducted on the perfluorohexane samples before and after pyrolysis. The FC-72 and n-PFH samples showed no significant degradation following pyrolysis even under the most aggressive study conditions. Some trace level impurities associated with the PFH samples such as linear perfluorocarbon monohydrides or monoiodides were destroyed by pyrolysis at the upper limit. Other trace level impurities such as olefinic or cycloolefinic perfluorocarbons were converted into oxidation products by pyrolysis. The purity of PFH following pyrolysis actually increased slightly as a consequence since these trace contaminants were effectively scrubbed from the samples. However, since the initial concentrations of the thermally-impacted impurities were so low, the net effect was trivial. A potential byproduct of exposure of perfluorohexane fluids to high temperatures is the production of perfluoroisobutene (PFiB), which is extremely toxic. An ultra-high sensitivity PFiB-specific analysis based on GC-MS with negative ion chemical ionization (NICI) detection was used to evaluate the samples following thermal stressing. The perfluorohexanes examined here under conditions reflective of the ISS TCCS environment showed no signs of PFiB production with an analytical detection limit of 10 part per billion (ppb v/v). Nomenclature BXF= Boiling eXperiment Facility ECLSS = Environmental Control and Life Support System EI = Electron Ionization FDA = Food and Drug Administration GC = Gas Chromatography HVAC = Heating, Ventilation and Air Conditioning ISRU = In-situ resource utilization

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The Inhalation Toxicity of Pyrolysis Products of Polytetrafluoroethylene Heated Below 500 Degrees Centigrade

Cited by 48 publications

References 7 publications

Toxicology of ultrafine particles:in vivostudies

Toxicology of ultrafine particles:in vivostudies

Lung Injury after Experimental Smoke Inhalation: Particle-Associated Changes in Alveolar Macrophages

Chemical Characterization and Thermal Stressing Studies of Perfluorohexane Fluids for Space-Based Applications

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