Thermal Decomposition Products
Teflon (PTFE: polytetrafluoroethylene)
CAS No. 9002-84-0


ACTIVITY: US EPA Pesticide List 3 Inert.

Teflon is used in pesticides as an Inert. According to a US EPA Final Rule of April 28, 2004:
Montmorillonite-type clay treated with polytetrafluoroethylene. Carrier. PTFE content not greater than 0.5% of clay (w/w). To be used in pesticide formulations applied to growing crops or to raw agricultural commodities after harvest.

Also, component used in plastic slow release tag.


Thermal Decomposition Products of Teflon

The chemicals identified are from the abstracts listed below.
• Information on Molecular formula, Structure, and Other Names are from Toxnet's ChemIDplus

Chemical Name CAS No.
Molecular formula
and Structure
Other Names
Carbonyl fluoride   1871-24-5


There are two CAS Numbers for Carbonyl fluoride. Both have been cited as Teflon thermal decomposition products

Carbonyl difluoride  

-- also known as

Carbonyl fluoride


CF2O or COF2

Name of Substance
Carbonyl difluoride
Carbonyl fluoride

Carbon difluoride oxide
Carbon fluoride oxide (COF2)
Carbon oxyfluoride (COF2)
Carbonic difluoride
Carbonyl oxyfluoride
Fluoroformyl fluoride

Difluorophosgene None

Formula from this website

Very little information available. Note the synonyms for Carbonyl difluoride (above): Fluophosgene and Fluorophosgene



Primary Name: Perfluoroethane

Freon 116

Hydrogen fluoride 7664-39-3
Hydrofluoric acid
Octafluorocyclobutane 115-25-3
Freon C-318


[many citations using this synonym. The primary name is Perfluorisobutylene]


See below - the primary name is Perfluorisobutylene.

Fluorine monoxide

referred to as "oxyfluorides (7783-41-7)"


Primary Name: Fluorine monoxide

Difluorine monoxide
Fluorine (di-)oxide
Fluorine monoxide
Fluorine oxide
Oxygen difluoride
Oxygen fluoride (OF2)

Perfluoroisobutylene 382-21-8


Tetrafluoroethylene 116-14-3

Excerpts from The Toxicology of Perfluoroisobutene by Jiri Patocka and Jiri Bajgar.

Perfluoroisobutene ... is a fluoro-olefin produced by thermal decomposition of polytetrafluoroethylene (PTFE), e.g., Teflon [1].

Overheating of PTFE generates fumes of highly toxic PFIB and poses a serious health hazard to the human respiratory tract. PFIB is approximately ten times as toxic as phosgene [2]. Inhalation of this gas can cause pulmonary edema, which can lead to death. PFIB is included in Schedule 2 of the Chemical Weapons Convention (CWC), as a result of the prompting by one delegation to the Conference on Disarmament [3]. The aim of the inclusion of chemicals, such as PFIB was to cover those chemicals, which would pose a high risk to the CWC. Subsequently PFIB, specifically, was included in the final text of the CWC.

Chemistry. PFIB is a strong electrophile, which reacts with all nucleophiles [4]. The high electrophilicity of PFIB is a result of the strong electron-attracting effects of the fluorine atoms of the trifluoromethyl groups and the conjugation of the fluorine’s p electrons with the double bond of the vinyl group. Several reactive intermediate species were identified in the reaction of PFIB with nitrone and nitroso spin trap agents, and, some of the expected reactive nucleophiles in vivo include amines, alcohols and especially thiols [5].

PFIB decomposes rapidly when dissolved in water, forming various reactive intermediates and fluorophosgene, which then decomposes into carbon dioxide, a radical anion and hydrogen fluoride [6]. PFIB is a gas with a boiling point of 7.0çC at one atm and a gas density of 8.2 g/L [9]. The synthesis of PFIB from fluorodichloromethane is given in Fig. 1.

Toxicology. The toxicity of PFIB may be correlated with its susceptibility to nucleophilic attack and the generation of reactive intermediates [1]. This is similar to the toxicity of other fluoro-olefins; their toxicity is directly proportional to the reactivity of that olefin with nucleophiles [7, 8].

Acute Toxicity. The median lethal concentration (LC50) in single exposures of rats was 0.5 ppm. The intoxicated rats either died with gross pathological signs of pulmonary congestion or recovered with no apparent residual effects. The 15-second LC50 was 361 ppm and the 10-minute LC50 was 17 ppm [9]. Similar high acute toxicity following inhalation was seen in other species with a two hour LC50 in mice reported to be either 1.6 ppm [9] or 0.98 ppm [10], in rabbits either 4.3 ppm [10] or 1.2 ppm [11], in guinea-pigs 1.05 ppm [10] and in cats 3.1 ppm [10]. In experiments in which rats were exposed to a concentration of 12.2 ppm for 10 min, an unusual postexposure latency period of approximately 8 hours was observed prior to the occurrence of pulmonary edema [12].

1. Zeifman, Y.B., Ter-Gabrielyan, N.P., Knunyants, I.L. The Chemistry of Perfluoroisobutylene. Uspekhi Khimii, 1984; 53: 431-461.
2. Oberdorster, G., Ferin, J., Gelein, J., Finkelstein, R., Baggs, R., Effects of PTFE Fumes in the Respiratory Tract: A Particle Effect? Aerospace Medical Assiciation 65th Annual Scientific Meeting, 1994; 538: A52.
3. CD/CW/WP.239. Verification of the Nonproduction of Chemical Weapons: An Illustrative Example of the Problem of Novel Toxic Chemicals. 12 April 1989.
4. England, D.C., Krespan, C.G. Fluoroketenes. I. Bis(trifluoromethyl)ketene and Its Reaction with Fluoride Ion. J Am Chem Soc, 1966; 88: 5582-5587.
5. Arroyo, C.M. The Chemistry of Perfluoroisobutylene (PFIB) with Nitrone and Nitroso Spin Traps: an EPR/Spin Trapping Study. Chem Biol Interact 1997; 105: 119-129.
6. Lailey, A.F., Hill, L., Lawston, I.W., Stanton, D., Upshall, D.G. Protection by Cysteine Esters Against Chemically Induced Pulmonary Oedema. Biochem Pharmacol 1991; 42: PS47-52.
7. Cook, E.W., Pierce, J.S. Toxicology of Fluoro-Olefins. Nature 1973; 242: 337-338.
8. Clayton, J.W. Toxicology of the Fluoroalkenes. Review and Research Needs. Environ Health Perspect 1977; 21: 255-267.
9. Smith, L.W., Gardner, R.J., Kennedy, G.L., Jr. Short-Term Inhalation Toxicity of Perfluoroisobutylene. Drug Chem Toxicol 1982; 5: 295-303.
10. Karpov, B.D. Determination of Upper and Lower Parameters of Perfluoroisobutylene Toxicity. Tr. Leningr Sanit Gig Med Inst 1975; 30: 111-120.
11. Paulet, G., Bernard, J.P. High Boilers Appearing During the Production of Polyfluorethylene. Biol Med 1968; 57: 247-301.
12. Lehnert, B.E., Archuleta, D., Gurley, L.R., Session, W., Behr, M.J., Lehnert, N.M., Stavert, D.M. Exercise Potentiation of Lung Injury Following Inhalation of a Pneumoedematogenic Gas: Perfluoroisobutylene. Exp Lung Res 1995; 21: 331-350.

Ref: Toxicology of Perfluoroisobutene by Jiri Patocka and Jiri Bajgar (Department of Toxicology, Military Medical Academy 500 01 Hradec, Czech Republic). The ASA Newsletter (Applied Science and Analysis, Inc.). 1998.


Abstract: Teflon (9002-84-0), a physically inert tetrafluoroethylene (116-14-3) resin, is discussed in a paper presented at the American Industrial Hygiene Association Annual Meeting in Cincinnati, Ohio on April 26, 1955, and it is noted that its pyrolytic products are toxic, and exposure to various mixtures of them will induce polymer fume fever in humans. The latter influenza like syndrome has not been reproduced in animals. Sufficiently intense exposure of animals to Teflon's thermal products, however, is generally lethal. The associated evidence of pulmonary edema, together with other early test results, originally suggested that hydrogen fluoride (7664-39-3) (HF) was the responsible toxic agent. The pyrolysis of Teflon starts at 200 degrees-C and proceeds slowly up to 420 degrees-C; at 500 to 550 degrees-C, the degradational weight loss reaches 10% to 5% per hour, respectively, depending on conditions. In the temperature range 300 to 360 degrees-C, hexafluoroethane (C2F6) and octafluorocyclobutane (C4F8) were identified as decomposition products. In the range 380 to 400 degrees-C, octafluoroisobutylene (also C4F8) could be detected and, at 500 to 550 degrees-C, the chief pyrolysis products other than tetrafluoroethylene (116-14-3) (C2F4) were hexafluoropropylene (116154), (C3F6) octafluorocyclobutane, and octafluoroisobutylene plus a complex residue of perfluoroolefins. Inhalation toxicity tests indicated that the octafluoroisobutylene gas, the most potent product, was approximately ten times as toxic as phosgene (75-44-5). The rat mortality factor seemed to be proportional to the product of exposure time and Teflon surface area as a function of pyrolysis temperature. Teflon 6, a lower molecular weight polymer than Teflon 1, produced more toxic pyrolysis products. Other kinds of industrial polymers were observed to produce lethal atmospheres under less drastic conditions than either form of Teflon.
Ref: Toxicity of Pyrolysis Products of "Teflon" Tetrafluoroethylene Resin by Zapp JA Jr, Limperos G, Brinker KC. Proceedings of the American Industrial Hygiene Association Annual Meeting, Cincinnati, Ohio, April 26, 1955.

Abstract: The toxic properties of the tetrafluoroethylene (9002-84-0) monomer and of products of the thermal treatment of the tetrafluoroethylene polymer in acute experiments on cats, rabbits, albino rats and albino mice are reported. In rats and rabbits the inhalation of monomer induced hyperemia of organs, especially the brain, hemorrhage in the spleen and lungs, and dystrophic changes in the kidneys. Emphysema and atelectasis was observed in the lungs, desquamation of the epithelium in the bronchi also was observed. The threshold mortality for the monomer was 2.5 volume percent for albino rats and 4.0 volume percent for rabbits. The pyrolytic decomposition of tetrafluoroethylene polymer was lethal to cats, rabbits, mice, and rats. Death was caused by acute pulmonary edema, sometimes accompanied by pneumonia. Renal dystrophy was observed in the cats. There was acute irritation of the upper respiratory tract mucosa in all test animals. It is concluded that the pathology observed upon inhalation of the products of thermal decomposition of the polymer is apparently explained by the presence in the pyrolyses gas of difluorophosgene, perfluoroisobutylene (382-21-8), and other highly toxic hydrocarbons. (Russian: English translation available)
Ref: Toxicity of Tetrafluoroethylene by Zhemerdi A. Trudy Leningradskogo Sanitarno-gigienicheskogo Meditsinskogo Instituta, Vol. 44, pages 164-176, 1958. Document Number: NIOSH/00080478.

Abstract. Toxic effects following inhalation exposure to polytetrafluoroethylene (9002-84-0) (PTFE) pyrolysis products were determined in rats. Greenacres-Flora-rats were exposed to PTFE pyrolysis products containing hydrolyzable fluoride equal to 50 parts per million of carbonyl fluoride (353-50-4) for 1 hour daily for 5 days. On day 1 and 5 of the exposure period, and 3, 7, and 18 days postexposure urine samples were collected and examined for fluoride excretion and glucose, protein, and ketones. On each of those days, a test animal was killed, and kidney and lung tissues were tested for succinic-dehydrogenase activity. Weight changes and mortality during the course of the experiment were also noted. During the 5 exposure days and shortly afterwards, mortality reached 22 percent, although the total exposure dose was less than half the median lethal dose for one exposure. Daily urinary fluoride excretion jumped to 14 times normal on the first exposure day and remained at 4 times normal by the eighteenth postexposure day. By the fifth exposure day, body weights dropped 30 percent, urine glucose, protein, and ketones were abnormal, and succinic-dehydrogenase activity dropped to near zero in the kidney and had more than doubled in the lung; by the eighteenth post exposure day, these values had returned to normal. The authors conclude that carbonyl fluoride generated during the pyrolysis of PTFE hydrolyzes in body fluids and produces fluoride toxicity. The cumulative effect of repeated exposures is much more toxic than a single equivalent exposure. If death does not result, the metabolic inhibition due to fluoride poisoning is completely reversible.
Ref: Biochemical Changes Associated with Toxic Exposures to Polytetrafluoroethylene Pyrolysis Products by Scheel LD, McMillan L, Phipps FC. American Industrial Hygiene Association Journal, Vol. 29, No. 1, pages 49-53, 1968.

Abstract: The pathologic effects of exposure to combustion products of polytetrafluoroethylene (9002-84-0) (PTFE) were studied in rats. Fischer-344-rats received single 30 minute exposures to concentrations from 0.005 to 5.025 milligrams per liter aerosol products of PTFE heated to 595 degrees-C. The median lethal concentration (LC50) was determined. Necropsies were performed at 0, 2, 12, 24, and 36 hours post exposure or between 2 and 17 days. The LC50 for thermal degradation products of PTFE was 0.045 milligrams per liter. Conjunctival erythema and serous occular and nasal discharge were seen in survivors immediately after exposure. Lesions were found in lungs of 84 percent of exposed rats. Focal hemorrhages, edema, and fibrin deposition in the lungs were found. Focal interstitial thickenings developed and increased. Alveolar macrophages became more severe up to 96 hours. Thrombosis or embolism of pulmonary capillaries and veins were found in 38 percent of exposed rats. The degree of pathologic change increased as the dose increased up to the LC50, but fluctuated above that. Disseminated intravascular coagulation occurred in 53 percent of exposed rats and was positively related to the amount of lung damage. Renal infarcts due to disseminated intravascular coagulation were found but no other kidney lesions were seen. The authors conclude that disseminated intravascular coagulation appears to be a consequence of exposure to PTFE combustion products.
Ref: Pathologic Findings In Rats Following Inhalation Of Combustion Products Of Polytetrafluoroethylene (PTFE) by Zook BC, Malek DE, Kenney RA. Toxicology, Vol. 26, No. 1, pages 25-36, 1983.

Oxygen difluoride is a thermal decomposition product of Teflon.
It has many synonyms; it's
primary name is Fluorine monoxide
(CAS No.
7783-41-7). The molecular structure is:

In the US National Institute for Occupational Safety and Health (NIOSH) category of Immediately Dangerous to Life or Health Concentrations (IDLH) - a list of 387 workplace chemicals - the two chemicals that share the rank of most dangerous chemicals for "respirator selection criteria" are:

Oxygen difluoride : IDLH of 0.5 ppm
Lithium hydride : IDLH of 0.5 mg/m3

Human data: Oxygen difluoride is a strong irritant to the entire respiratory tract and causes pulmonary edema and hemorrhage when inhaled for a few hours at 0.5 ppm [Deichmann and Gerarde 1969].

Basis for original (SCP) IDLH: The chosen IDLH is based on the statements by Deichmann and Gerarde [1969] that oxygen difluoride is a strong irritant to the entire respiratory tract and causes pulmonary edema and hemorrhage when inhaled for a few hours at 0.5 ppm. Development of pulmonary signs leading to death may be delayed several hours after the exposure [Deichmann and Gerarde 1969]. In addition, AIHA [1967] reported that the Committee on Toxicology of the National Research Council recommended an Emergency Exposure Limit (EEL) of 0.5 ppm for a 10-minute exposure. This EEL is supposed to be for exposures that are "rare in the lifetime of an individual and permit some degree of reversible injury short of incapacitation" [Smyth 1966].

Lethal concentration data:
Reference LC50 (ppm) Time Adjusted 0.5-hr LC (CF) Derived value
Rat Darmer et al. 1972
1 hr 3.3 ppm (1.25) 0.3 ppm
Mouse Darmer et al. 1972
1 hr 1.9 ppm (1.25) 0.2 ppm
Dog Darmer et al. 1972
1 hr 33 ppm (1.25) 3.3 ppm
Monkey Darmer et al. 1972
1 hr 20 ppm (1.25) 2.0 ppm


AIHA [1967]. Oxygen difluoride. In: Hygienic guide series. Am Ind Hyg Assoc J 28:194-196.

Darmer KI Jr, Haum CC, MacEwen JD [1972]. The acute inhalation toxicology of chlorine pentafluoride. Am Ind Hyg Assoc J 33:661-668.

Deichmann WB, Gerarde HW [1969]. Oxygen difluoride (OF2). In: Toxicology of drugs and chemicals. New York, NY: Academic Press, Inc., p. 444.

Smyth HF Jr [1966]. Military and space short-term inhalation standards. Arch Environ Health 12:488-490.

CAS Registry Number: 382-21-8 (Perfluoroisobutylene)
Report Nos. NTIS/OTS0539061-1.
EPA/OTS; Doc #89-930000107.

Report Nos.
NTIS/OTS0571216. EPA/OTS; Doc #88-920009560.

CAS Registry Numbers:
116-15-4 (Hexafluoropropene)
353-50-4 (Carbonyl fluoride, also known as Carbonyl difluoride)
382-21-8 (Perfluoroisobutylene)
Report Nos. NTIS/OTS0555698. EPA/OTS; Doc #88-920010279.

116-15-4 (Hexafluoropropene)
353-50-4 (Carbonyl fluoride, also known as Carbonyl difluoride)
382-21-8 (Perfluoroisobutylene)
Report Nos. NTIS/OTS0571353. EPA/OTS; Doc #88-920009696.

CAS Registry Numbers:
116-15-4 (Hexafluoropropene)
303-50-4 (Desmethylcyclobenzaprine)

Report Nos.
NTIS/OTS0215306. EPA/OTS; Doc #878220598.

CAS Registry Numbers:
116-15-4 (Hexafluoropropene)
422-55-9 (Propane, 1-chloro-1,1,2,2,3,3-hexafluoro).
Report Nos. NTIS/OTS0215306. EPA/OTS; Doc #878220596.

Abstract: Perfluoroisobutene (PFIB) is produced by the pyrolysis, and as a by-product during the manufacture, of polytetrafluoroethylene. When inhaled it produces a fulminating and sometimes fatal pulmonary oedema similar to that of phosgene after a latent peroid of 6-8 h. As part of a study to determine the retained dose and the factors that control the amount retained, this study has investigated the retention in rats of inhaled PFIB at concentrations of 10, 50 and 250 mugl/-1 in a flow-through system combining head-only exposure and plethysmography. Uptake of PFIB was measured by gas chromatography during elevated and reduced inspired volume and respiratory rate induced by exposure to increased CO2 and injection of pentobartione, respectively. The percentage of PFIB retained in the upper airways and lungs was found to be 27.5, 28.1 and 23.7% of the amount inspired at the three concentrations tested. The rate of uptake (nmol min-1 kg-1) of PFIB was a power law of the amount inha [astract truncated]
Ref: Retention of inhaled perfluoroisobutene in the rat. by MAIDMENT MP, UPSHALL DG. J APPL TOXICOL; 12 (6). 1992. 393-400.

Abstract: Fluoropolymers, especially polytetrafluoroethylene (PTFE), have good fire-resistance properties, but their application is limited by concerns over the toxicity of their thermal decomposition products. In experiments using a tube furnace system similar to the DIN 53 436 method, the 30-minute (+ 14 days observation) LC50 im mass loss terms was found to be 2.9 mg l-1 (Standard Error 0.04) under non-flaming conditions, approximately ten times as toxic as wood and most other materials. Toxicity was due to upper respiratory tract and airway irritation, and was consistent with the known effects of carbonyl fluoride and hydrogen fluoride. When decomposed in the NBS cup furnace test under non-flaming conditions, PTFE evolved extreme-toxicity products with an LC50 of approximately 0.05 mg l-1 (mass loss), approximately 1000 times as toxic as wood and most other materials. Toxicity was due to deep lung irritation and oedema. Investigations of the range of conditions under which the [abstract truncated]
Ref: Recent developments in understanding the toxicity of PTFE thermal decomposition products. by PURSER DA. FIRE MATER; 16 (2). 1992. 67-75.

Abstract: The toxic effects of thermal degradation products of polytetrafluoroethylene (9002-84-0) (PTFE) and tetrafluoroethylene (116-14-3) / hexafluoropropylene (116-15-4) copolymer (FEP) were studied in rats. Twenty two male Crl:CD-BR-rats were exposed to FEP pyrolysis products in a National Bureau of Standards (NBS) exposure chamber for 30 minutes; 4 rats were killed 1 to 4 hours after for microscopic examination of lung and nasal sections and the remaining 18 were observed for 24 hours post exposure. Four rats exposed to air only were used as controls. Further experimentation involved exposure of 14 rats to PTFE pyrolysis products in a low temperature decomposition exposure system for 4 hours; again, some rats were killed 1 to 4 hours thereafter for microscopic evaluations and the remaining rats were observed for 24 hours. Determinations were made regarding the presence of gaseous hydrogen fluoride and particle size. An intratracheal instillation experiment was also conducted in which rats were exposed to 0.05 milligrams aged PTFE particulate agglomerates and their lungs were examined microscopically. In the NBS chamber, the approximate lethal concentration (ALC) of particulate generated was 0.3mg/m3 of FEP pyrolysis products; in the second chamber, the ALC of fume evolved from PTFE was 0.1mg/m3. Fresh particles, 0.02 to 0.15 micrometers, were thought to be the toxic agents. In the inhalation studies, exposed rats died from pulmonary congestion and edema but only minimal respiratory epithelial damage was seen in the nasal cavity or airways. Pulmonary lesions were characterized by alveolar and interstitial edema and intraalveolar hemorrhage due to damaged Type-I pneumocytes and were associated with alveolar capillary neutrophilia. The authors recommended investigation of the mode of action of PTFE particulates on Type-I pneumocytes.
Ref: Pulmonary Response of Rats Exposed to Polytetrafluoroethylene and Tetrafluoroethylene Hexafluoropropylene Copolymer Fume and Isolated Particles. by Lee KP, Seidel WC. Inhalation Toxicology, Vol. 3, No. 3, pages 237-264, 53 references, 1991.

Abstract: Information on potential occupational hazards from exposure to carbonyl fluoride (353-50-4) was reviewed. Topics discussed included chemical and physical properties, production, use, manufacturers and distributors, manufacturing processes, occupational exposure, and biological effects. Potential exposure to carbonyl fluoride occurs as a result of the thermal decomposition of polytetrafluoroethylene (PTFE) in air. Effects of acute exposure in animal studies included extreme malaise and weakness which preceded death. Subchronic exposure studies with PTFE pyrolysis products revealed pathologic changes in the respiratory tracts and livers of exposed animals. Protein, glucose, ketones, and occult blood appeared in the urine following exposure. No information was available concerning chronic exposures, carcinogenicity, mutagenicity, teratogenicity, or reproductive effects.
Ref: 1987. Information Profiles on Potential Occupational Hazards: Carbonyl Fluoride. Second Draft. Syracuse Research Corp., NY. Center for Chemical Hazard Assessment. Sponsored by National Inst. for Occupational Safety and Health, Rockville, MD. Report No. NTIS/PB87-174330.


CAS Registry Numbers:

7664-39-3 (Hydrofluoric acid)
630-08-0 (Carbon monoxide)
124-38-9 (Carbon Dioxide)
116-15-4 (Hexafluoropropene)

Abstract: The relative toxicities of thermal degradation products from four fluoropolymers were determined in rats. The polymers were polytetrafluoroethylene (9002-84-0) (PTFE), copolymers of vinylidene fluoride (75-38-7) and hexafluoropropene (116-15-4) with and without additives (VF2-A and VF2/HFP), and the terpolymers of PTFE, VF2, and HFP (VF2/HFP/TFE). Male Sprague-Dawley-rats were exposed for 30 minutes to the pyrolysis products of VF2/HFP, VF2/HFP-A, and VF2/HFP/TFE at 550 and 800 degrees-C, and to the pyrolysis products of PTFE at 625 and 800 degrees-C. Survivors were killed at 1, 2, 4, 8, 16, and 32 days postexposure and examined for pathological changes in organs and tissues. Hydrolyzable fluoride concentrations were determined for pyrolysis products of all polymers at both temperatures. At 550 degrees-C, the median lethal dose ranged from 1.06 grams (g) VF2/HFP-A to 2.36g VF2/HFP. The median lethal dose of PTFE at 625 degrees-C was 0.5g. At 800 degrees-C, the median lethal dose ranged from 0.38g PTFE (for a 5 minute exposure) to 0.59g VF2/HFP (for a 30 minute exposure). Initial pathological response to pyrolysates included capillary damage leading to pulmonary edema, and alveolar hypertrophy and desquamation. For survivors, edema was resolved and a proliferative phase began after 48 hours. Lungs returned to normal after 1 week. No other organ system was involved. No relationship was found between hydrolyzable fluoride concentrations of pyrolysates and toxicities. The authors conclude that the pyrolysis products of PTFE are more toxic than those of polymers containing VF2 and HFP.
Ref: The Acute Inhalation Toxicity in Rats from the Pyrolysis Products of Four Fluoropolymers. by Carter VL Jr, Bafus DA, Warrington HP, Harris ES. Toxicology and Applied Pharmacology, Vol. 30, No. 3, pages 369-376, 9 references, 1974.

Abstract: Urinary fluoride levels were investigated as an index of polytetrafluoroethylene (PTFE) exposure, since carbonyl fluoride, a pyrolysis product of PTFE, is metabolized and excreted as inorganic fluoride ion. Spot urine samples and occupational histories relating to polyment fume fever were obtained from 77 workers at a small PTFE fabricating plant. Environmental air samples for PTFE were taken. Air levels of PTFE ranging from 0-5.48 mg/m-3 were found. All urine values fell below the level at which systemic effects are reported to occur. Analysis of variance demonstrated that the mean urinary fluoride level among workers who had 1 or more years of exposure to PFTE who also had experienced 1 or more reported episodes of polymer fume fever was significantly higher (P< 0.01) than that among employees with less than 1 yr or more of exposure and no history of polymer fume fever. Additional exposure beyond 1 yr and additional polymer fume fever episodes did not result in the further elevation of urine fluoride levels.
Ref: Urinary fluoride levels in polytetrafluoroethylene fabricators; POLAKOFF PL, BUSCH KA , OKAWA MT. AM IND HYG ASSOC J; 35 (2). 1974 99-106.

Abstract: Environmental survey of the hazards arising from Teflon (9002-84-0) dust and noise in a plastics industrial unit. Total dust air concentration levels obtained from 23 persons and four general area samples range from 0.0 to 5.5 milligrams per cubic meter, as against the standard of 15 milligrams per cubic meter. Recommendations include improved housekeeping program to keep dust sources to a minimum, prohibition of smoking in areas where Teflon is cut, machined, or processed, reduction of noise levels to within standards of 90 decibels by instituting engineering controls, establishment of a hearing conservation program including audiometry, and use of personal protective devices. Symptoms of Teflon fume fever are given with effects of smoking Teflon-contaminated cigarettes, which include chills, nausea, vomiting, body and joint pains, sweating, weakness, and dry cough. Polytetrafluoroethylene is not considered damaging to skin when used at ordinary temperatures. Above 400 degrees centigrade, perfluorisobutylene and carbonyl fluoride (353504) are formed by the pyrolysis of Teflon.
Ref: Health Hazard Evaluation Report HHE-72-29-28, Modern Industrial Plastics Division, Duriron Company, Dayton, Ohio. by Okawa MT, Polakoff PL. Hazard Evaluation Services Branch, NIOSH, Cincinnati, Ohio, Report No. HHE-72-29-28, 28 pages, 12 references, 1973.

Abstract: A literature survey relating to the processes occurring in the decomposition of polyfluoroethylene (9002-84-0) resins, depending upon the heating temperature, and toxicological data, is presented. The work conditions during the thermal treatment of polyfluoroethylene resins were studied by taking samples of objects baked in closed door ovens at temperatures of from 375 to 415 degrees C. It was determined that the atmosphere can be polluted with such compounds as perfluoroisobutylene, tetrafluoroethylene (116-14-3), oxyfluorides (7783-41-7), hydrogen fluoride, carbon-monoxide (630080), and polymer aerosols. The implementation of preventive measures, such as: 1) isolating the ovens from other work sections; 2) constructing block exhaust ventilations from the heating ovens; 3) hermetically sealing the oven doors; 4) constructing exhaust vents tightly adhering to the upper oven walls; and 5) daily controls of the atmosphere, permitted the reduction of toxic pollutants in the atmosphere. It is concluded that the thermal processing of polyfluoroethylene resins required the special attention of hygienists and engineering personnel. (Russian: English translation available)
Ref: Fundamental Problems of Industrial Hygiene in the Processing of Polyfluoroethylene Resins. Marchenko FM. Gigiena Truda i Professional'nye Zabolevaniia, Vol. 10, No. 11, pages 12-18, 9 references, 1968.

Abstract: Thirty payroll and eight staff employees of a polytetrafluoroethylene (9002-84-0) (PTFE) manufacturing plant were interviewed and the plant investigated to determine the cause of polymer fume fever in plant employees. Fourteen of the 30 payroll employees had experienced symptoms of the fever in the two months previous to the interview. Thirty-two incidents of polymer fume fever were reported by these 14 workers. Only employees working in the finishing room, where PTFE was dried, sifted, and packed, had been affected. Of the 18 men who worked in the finishing room, 12 who were smokers accounted for 30 incidents. Six of the workers who rolled their own cigarettes had incurred 21 of these 30 attacks. Of the eight staff employees, only one, a pipe smoker, had experienced an attack of polymer fume fever. Air samples were taken in the finishing room at points close to the drying ovens and the ovens where the polymer was further heated when required. When PTFE was heated to normal drying temperatures, hydrochloric acid (7647010) was occasionally detected in concentrations up to 35ppm. Hydrogen fluoride (7664-39-3), in concentrations no greater than 6ppm, was detected when the temperature was increased beyond 300 degrees-C. The results indicate that the majority of incidents of polymer fume fever resulted from the smoking of PTFE contaminated tobacco. Precautionary measures, designed to prevent further incidents of polymer fume fever, were recommended.
Ref: Polymer Fume Fever Due to Inhalation of Fumes from Polytetrafluoroethylene. by Adams WGF. Transactions of the Association of Industrial Medical Officers, Vol. 13, pages 20-21, 4 references, 1963.

Abstract: Guidelines for the safe handling and use of "Teflon" fluorocarbon resins, specifically polytetrafluorethylene (9002-84-0) (PTFE) and fluorinated-ethylene-propylene (FEP) polymers manufactured by the DuPont Company, are given. Although no hygienic standard for PTFE and FEP dusts has been set, a maximum atmospheric concentration of 15mg/cubic meter may be tolerated over an 8 hour period on a nuisance basis without significant hazard, since the oral and inhalation toxicities of the undecomposed polymers are practically nil. Decomposition products appear only at temperatures above 200 degrees-C. No practical way has yet been devised to express safe concentrations of the various possible mixtures of the decomposition products, which include tetrafluoroethylene (116-14-3), hexafluoropropylene (116-15-4), octafluoroisobutylene, and hydrogen fluoride (7664-39-3). Above 250 degrees-C, toxicologically significant amounts of these products are evolved and polymer fume fever may result from exposure to them or from smoking Teflon contaminated cigarettes. The decomposition products become flammable above 690 degrees-C. The general physical and chemical properties of the two resins are presented, but there are no identifying characteristics of taste, odor or irritation. Based on results reported from both animal and human toxicity studies, recommendations are given for monitoring the atmosphere for fluorine (7782-41-4) containing gases, for minimizing worker exposure during operations generating high temperatures (including machining Teflon parts, smoking, and fire fighting), and for first aid procedures.
Ref: "Teflon" Fluorocarbon Resins and Their Decomposition Products. Anonymous. American Industrial Hygiene Association Journal, Vol. 24, pages 198-200, 8 references, 1963.

Abstract: Studies by the du Pont Company investigating the toxicity of pyrolysis products of two tetrafluoroethylene (TFE) resins, Teflon-1 and Teflon-6 (9002-84-0) are reviewed. TFE resins are physiologically inert, but when subjected to temperatures of 300 degrees-C and above, toxic effects in rats are observed. In addition to causing death of experimental animals, toxic symptoms include pulmonary congestion and edema, bronchitis, bronchopneumonia, chronic pneumonia, and emphysema. As temperature increases above 300 degrees-C, the rate of thermal decomposition increases and the pyrolysis products change. Small quantities of carbon dioxide and fluorides that do not appear to be important toxicologically are evolved when TFE resins are exposed to temperatures from 300 to 350 degrees-C. However, a fine particulate material evolving during pyrolysis is toxic to rats. The observed toxicity of pyrolysis products heated to 380 degrees-C and above may be due chiefly to octafluoroisobutylene [also known as Perfluoroisobutylene] (382-21-8). The relative toxicity of pyrolysis products of Teflon-1 and Teflon-6 corresponds to the amount of matter evolved. Filtration of the pyrolysis stream significantly reduces the toxicity of the products evolved at temperatures of 325 and 350 degrees-C. New manufacturing techniques for TFE resins have resulted in products with improved thermal stability and corresponding lower toxicity of pyrolysis products. The authors conclude that experimental work is still needed to allow exact characterization of the toxic pyrolysis products of TFE resins.
Ref: The Toxicity of the Pyrolysis Products of "Teflon" TFE-Fluorocarbon Resins. Clayton JW Jr, Hood DB, Raynsford GE. Haskell Laboratory for Toxicology and Industrial Medicine, E. I. du Pont de Nemours and Co., Inc., Wilmington, Delaware, Presented at the American Industrial Hygiene Association Annual Meeting, 9 pages, 1959.

Abstract: Teflon (9002-84-0) vapor toxicity under various thermal conditions is reviewed. It is noted that under normal usage conditions Teflon is among the most inert, nontoxic, and nonflammable substances tested. The primary uses of Teflon are described. Its nontoxic nature has been proven by animals tests. At 200 degrees-C or higher Teflon decomposes to release toxic fumes which cause polymer fume fever in humans. The incidence of this reaction among Teflon workers is discussed and the symptoms described. It is noted that the effects last for 1 to 2 hours but rarely longer, and recovery is complete within 24 to 36 hours. The rate of decomposition of Teflon resins at various temperatures ranging from 200 to 500 degrees is described and the products of pyrolysis at these temperatures are specified. The major component of pyrolysis at 400 degrees is the monomer tetrafluoroethylene (116-14-3) a relatively innocuous gas which comprises at least 95 to 97 percent of the gaseous output and hexafluoropropylene (116-15-4) (2 to 3 percent). Trace amounts of hydrogen fluoride (7664393) have also been detected especially in the presence of moisture during Teflon pyrolysis, as well as perfluoroisobutylene (382-21-8). The toxicity of the latter two compounds in animals is discussed. The toxic response in animals is reviewed in terms of human maximal allowable concentrations. Other features of the pyrolytic decomposition of Teflon such as weight loss at various temperatures is tabulated. Control measures for storage of Teflon and other fluorocarbon plastics, fabrication, installation and maintenance of components utilizing Teflon and disposal of scrap Teflon are discussed as well as personal hygiene, ventilation during heating of Teflon, use of emergency personal protective equipment, and maintenance of adequate medical records.
Ref: Environmental And Occupational Health Information Letter Number 13A. Toxicity Of Products Of Thermal Decomposition Of Teflon. Anonymous. Office of the Surgeon, Air Material Command, Wright-Patterson Air Force Base, Ohio, 7 pages, 9 references, 1958.

Abstract: The effects of various gaseous atmospheres on the thermal decomposition of polytetrafluoroethylene (9002-84-0) were investigated. The rate of degradation was measured by determining the weight loss of 1 gram of the polymer after periodic heating to between 450 and 500 degrees-C in the presence of various flowing gases. Gases studied including those exhibiting a strong catalytic effect on the rate of degradation, such as oxygen (7782447) (O2), nitrous-oxide (10024972), hydrogen-sulfide (7783064), and sulfur-dioxide (7446095); those producing an initial inhibitory effect, as hydrogen (1333740) (H2), chlorine (7782505), carbon-tetrachloride (56235), and toluene (108883); and those that showed neither effect, nitrogen (7727379), and benzotrifluoride (98-08-8). Gaseous products were characterized and quantitated. With O2, the major product was carbon-dioxide (124389) (CO2); perfluoroethylene (116-14-3), silicon tetrafluoride (7783-61-1), and CO2 in equivalent amounts were the major products of H2; with toluene the major product was perfluoroethylene. Those gases giving catalytic effects did so by increasing transfer mechanisms or defluorination. Those showing inhibition effects gave kinetic curves with inflection points, and there was a change in the mechanism as noted by the product distribution. The authors conclude that although the inhibited reactions produce few monomers and are highly random, there are relatively high rates of induced decomposition.
Ref: Thermal Decomposition of Polytetrafluoroethylene in Various Gaseous Atmospheres. Wall LA, Michaelsen J. Journal of Research of the National Bureau of Standards, Vol. 56, No. 1, pages 27-34, 12 references, 1956.

Abstract: The necessity of conducting thermochemical studies on fluorocarbons is discussed in light of the growing industrial importance of such compounds, and because relatively little information was previously available about heats of formation and other properties. Measurements were therefore made of the heat evolved in: 1) the explosive decomposition of tetrafluoroethylene (116-14-3) (TFE); 2) the explosive hydrogenation of TFE; and 3) the formation of two kinds of combustion products from TFE. The combustion reactions are general and were applied to TFE, hexafluoropropylene (116154), octafluorocyclobutane (115-25-3), and Teflon (9002-84-0) or polytetrafluoroethylene (9002-84-0) (PTFE). By combining the results of these measurements with established values for hydrogen fluoride (7664-39-3) and carbon-dioxide , the heats of formation of all the compounds involved in the reactions were obtained and compared with other values reported in the literature. In particular, the values obtained for carbon tetrafluoride (75-73-0), 212.7kcal, and for TFE, 151.3kcal, are lower than those reported by other investigators, but the value for the polymer PTFE, 199.9kcal, is higher. The experimental details regarding apparatus, materials, and procedures used are presented in full, and heats of formation are arranged in tabular form.
Ref: Thermochemical Studies on Fluorocarbons: Heat of Formation of CF4, C2F4, C3F6, C2F4 Dimer, and C2F4 Polymer. Duus HC. Industrial and Engineering Chemistry, Vol. 47, No. 7, pages 1445-1449, 12 references, 1955.

Abstract: The mechanism of thermal breakdown of teflon (9002-84-0) and related fluoropolymers as obtained by S. L. Madorsky and associates at the National Bureau of Standards is described. A pyrolysis method was used involving thermal decomposition of a sample and subsequent distillation under such a high vacuum that there was no return of escaping molecules to the evaporating surface. Under these conditions, the fragments into which the polymeric chain is decomposed by heat could be collected without further fragmentation due to molecular collision. To obtain the activation energy of the polymers (a measure of the ease of decomposition), it was necessary to determine the rate of volatilization from each polymer sample over a suitable temperature range by measuring the weight loss in vacuum. In the case of Teflon, which yields mostly monomer breakdown products from the chain ends, pressure measurements of the volatiles produced in a fixed volume could also be used for the same purpose. Substitution of one or more hydrogen (1333740) atoms for fluorine (7182414) on the chain changes radically the polymer and its mechanism of breakdown. In the order of decreasing stability, as indicated by their temperature threshold for appreciable decomposition, the polymers tested are: Teflon, at 490 degrees-C; polyvinylidene fluoride, at 430 degrees-C; and polyvinyl fluoride and polytrifluoroethylene below 400 degrees-C. The latter two yield large amounts of long chain molecular fragments on heating, whereas polyvinylidene fluoride gives off a relatively larger percent of hydrogen fluoride (7664-39-3).
Ref: Thermal Stability of Teflon. Anonymous. National Bureau of Standards, Technical News Bulletin, Vol. 38 No. 3, pages 43-45, 7 references, 1954.

Abstract: Polytetrafluoroethylene (9002-84-0), a polymeric material possessing good heat stability and chemical inertness, was pyrolytically cracked at temperatures ranging from 600 to 700 degrees-C and at pressures between 5 and 760mm and the thermal degradation products were isolated using the Podbielniak distillation method. The products of thermal cracking were of low molecular weight and consisted of C2F4, which was identified as tetrafluoroethylene (116-14-3); C4F8, identified as octafluorocyclobutane; and C3F6, which was not identified during the study. These three compounds were formed in varying amounts depending on the experimental conditions. Tetrafluoroethylene was formed in increasing amounts as the pressure was decreased and was the sole product as very low pressures. At higher pressures, the yield of tetrafluoroethylene decreased, and C3F6 and octafluorocyclobutane were formed in increasing proportions. Increasing the temperature from 600 to 700 degrees-C had only a minor effect on the composition of the thermal degradation products. Results suggest:
1) that the original polymer (polytetrafluoroethylene) decomposes by splitting off units of the basic monomer (tetrafluoroethylene) from a degrading fragment, and
2) that these monomer units are capable of undergoing secondary reactions, favored by increased pressure, to form compounds of higher molecular weight. A mechanism consistent with this explanation is provided.
Very few carbon (7440440) to fluorine (7782414) bonds appear to be broken by direct attack of an active fragment.
Ref: Pyrolysis of Polytetrafluoroethylene. Lewis EE, Naylor MA. Journal of the American Chemical Society, Vol. 69, pages 1968-1970, 14 references, 1947.

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