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Halon-1301 (CF3Br) can make Br radicals with UV radiation, which poses a great threat to the ozone layer in the atmosphere. Necessary methods should be taken for the degradation of the exhausts of Halon-1301. In this paper, density functional (DFT) theory at B3LYP/6-311G++(d,p) level are employed for the study of dissociation properties and spectra of Halon-1301 in external electric field, including bond length, total energy, HOMO-LUMO energy gap, infrared spectra and dissociation potential energy surface (PES). The obtained results show that, with gradually increasing the external field from 0 to 0.03 a.u. along the molecular axis Z (C—Br bond direction), the total energy decreases, while the dipole moment decreases at the beginning and then increases. With the climbing of the field, HOMO-LUMO energy gap increases, and C—Br bond length increases while C—F bond length decreases. The variations of vibrational frequency and intensity of molecular IR spectra in external electric field are also investigated. Further studies show that with increasing the external electric field from 0 to 0.03 a.u., the dissociation PES along C—Br bond becomes unbound with disappearing of the barrier for the dissociation. The external electric field of 0.03 a.u. is sufficient to induce the degradation of CF3Br with C—Br bond breaking. Such results provide an important reference for the degradation of Halons via the external electric field.

Context: Although there are ample data on the respiratory effects of exposure to fire extinguisher gas, the potential hematologic effects have not been fully documented. We conducted this study to determine the possible etiologic agent(s) for a decrease in red blood cells among community residents in Taipei, Taiwan, after they were exposed to leakage of mixed fire extinguishants containing bromotrifluoromethane (CF3Br, Halon 1301), bromochlorodifluoromethane (CF2BrCl, Halon 1211), and dichlorodifluoromethane (CCl2F2, CFC-12). Case presentationWe studied 117 exposed residents who came into one hospital for physical examinations. We also selected age- and sex-matched referents for comparison from residents who came to the same hospital for health examinations. Nine months after the exposure to mixed fire extinguishants, 91 of the exposed residents came back for a second physical examination. In the first examination of the exposed residents, we found a significant reduction in red blood cell count and hemoglobin and a relationship between dose and response.DiscussionAfter excluding iron-deficiency anemia, thalassemia, and other possible agents, we suspected that the hematologic effects might have resulted from pyrolytic products of CFC-12 and Halon 1211, which may contain phosgene, among other products. Relevance to clinical practice: The acute transient hematologic effects observed in the exposed residents were associated with the incident of leakage of mixed fire-extinguisher gases and were most likely caused by a small amount of pyrolytic products, probably phosgene. Nine months after the exposure, we found a significant improvement in the abnormalities without any specific treatment. Language: en

The gas-phase reaction of halon 1211 (CBrClF2) with hydrogen has been studied experimentally at atmospheric pressure in a plug flow, isothermal reactor over the temperature range of 673 to 973 K, at residence times ranging from 0.5 to 2.5 s with an input ratio of N2:H2:halon 1211 of 19:10:1. The major carbon containing products include CHClF2, CHBrF2, CH2F2, and CH4. Gas-phase reactions of CHClF2, CCl2F2, and CH 2F2 with hydrogen are also investigated under the conditions similar to those for halon 1211 hydrodehalogenation, and the results are used to assist in understanding the mechanism of the reaction of halon 1211 with hydrogen. A kinetic reaction scheme involving 90 species and 430 reaction steps is developed and used to model the halon 1211 hydrodehalogenation reaction. Generally, satisfactory agreement between experimental and computational results is obtained for the production of major species. Using the software package AURORA, the reaction pathways leading to the formation of major products are elucidated. It has been found that the reaction steps involving CF2 are responsible for the formation of CH4.

Experimental information on the Csingle bondX⋯π halogen bonding motif was obtained by studying the formation of molecular complexes of CF3Cl, CF3Br and CF3I with ethyne, propyne and 2-butyne in liquid krypton, using FTIR and Raman spectroscopy. For CF3Br, experimental evidence was found for the formation of 1:1 complexes with propyne and 2-butyne only, while for CF3I spectroscopic features confirming the existence of the halogen bonded complexes were observed for ethyne, propyne and 2-butyne. In addition, at higher concentrations of CF3I and 2-butyne, weak absorptions due to a 2:1 complex were also observed. The experimental complexation enthalpies, obtained by using spectra recorded at temperatures between 120 K and 140 K, are −5.9(3) kJ mol−1 for CF3I.ethyne, −5.6(3) kJ mol−1 for CF3Br.propyne, −8.1(2) kJ mol−1 for CF3I.propyne, −7.3(2) kJ mol−1 for CF3Br.2-butyne, −10.9(2) kJ mol−1 for CF3I.2-butyne and −20.9(7) kJ mol−1 for (CF3I)2.2-butyne. The experimental study is supported by theoretical data obtained from ab initio calculations at the MP2/aug-cc-pVDZ(-PP) and MP2/aug-cc-pVTZ(-PP) levels, and Monte Carlo Free Energy Perturbation (MC-FEP) simulations. The experimental and theoretical values on the Csingle bondX⋯π halogen-bonding motifs studied are compared with previously reported data for the complexes with ethene and propene and with preliminary results obtained for benzene and toluene.

Trifluoroiodomethane (CF3I) and 1,1,2,2,3,3,3-heptafluoro-1-iodopropane (C3F7I) have been considered as replacement candidates for halon fire suppressants due to their excellent fire extinguishant capabilities and low ozone depletion potential compared to halon fire extinguishants in use currently. As part of the process to develop environmental and health effects criteria for halon substitutes, a cardiac sensitization test was conducted in beagle dogs. Cardiac sensitization to adrenaline is a phenomenon associated with the inhalation of a number of unsubstituted and halogenated hydrocarbons. Adrenaline was administered by intravenous injection before and during inhalation of the test substance. CF3I was administered to dogs at concentrations in air of 0.1, 0.2, 0.4 or 1% v/v. At each of 0.4 and 1.0% CF3I, the first dog exposed developed fatal ventricular fibrillation, and no further dogs were exposed at these concentrations. There was no cardiac sensitization at 0.1 or 0.2% CF3I. For the C3F7I experiment, dogs were exposed to concentrations in air of 0.1, 0.2 or 0.4% v/v. At each of 0.1 and 0.4% C3F7I, one dog responded with multifocal ventricular ectopic beats. Thus, CF3I and C3F7I are potent cardiac sensitizers in the adrenaline-challenged dog model.

Thermal rate constants and product branching fractions for electron attachment to CF3Br and the CF3 radical have been measured over the temperature range 300-890 K, the upper limit being restricted by thermal decomposition of CF3Br. Both measurements were made in Flowing Afterglow Langmuir Probe apparatuses; the CF3Br measurement was made using standard techniques, and the CF3 measurement using the Variable Electron and Neutral Density Attachment Mass Spectrometry technique. Attachment to CF3Br proceeds exclusively by the dissociative channel yielding Br-, with a rate constant increasing from 1.1 x 10(-8) cm(3) s(-1) at 300 K to 5.3 x 10(-8) cm(3) s(-1) at 890 K, somewhat lower than previous data at temperatures up to 777 K. CF3 attachment proceeds through competition between associative attachment yielding CF3- and dissociative attachment yielding F-. Prior data up to 600 K showed the rate constant monotonically increasing, with the partial rate constant of the dissociative channel following Arrhenius behavior; however, extrapolation of the data using a recently proposed kinetic modeling approach predicted the rate constant to turn over at higher temperatures, despite being only similar to 5% of the collision rate. The current data agree well with the previous kinetic modeling extrapolation, providing a demonstration of the predictive capabilities of the approach.

Although the neurological and cardiovascular effects of Freons have been extensively described, the respiratory effects have been less well documented. We report four cases of occupational asthma following accidental exposure to bromochlorodifluoromethane (Halon 1211) due to release of the contents of a fire extinguisher. All subjects developed an irritative reaction of the upper airways and lower respiratory symptoms immediately after exposure. Non-specific bronchial hyperreactivity was present for at least two months in all subjects and was still present more than two years after exposure in one case. The diagnosis of reactive airways dysfunction syndrome can be adopted in at least three of these four cases.

Bromotrifluoromethane (CBrF3), commonly known as Halon 1301, is used as a fire extinguishant in the Space Shuttle. Several scenarios, such as a fire or a faulty alarm, could lead to its discharge resulting in a Halon 1301 concentration of up to 1% in the spacecraft cabin atmosphere. To examine the effects of Halon 1301 on mental performance and physiologic function, the National Aeronautics and Space Administration sponsored a human inhalation study. Four pairs of adult male subjects were each exposed in a double-blind fashion for 24 hr to 1% (10,000 ppm or 60,875 mg/m3) Halon 1301 and to air in two separate exposures approximately 1 week apart. Mental performance and physiologic function were assessed and the results are reported in a companion paper (D. S. Calkins, J. J. Degioanni, M. N. Tan, J. R. Davis, and D. L. Pierson. Fundam. Appl. Toxicol. 20, in press). Blood and breath samples from the exposed subjects were also collected to provide dosimetric and toxicokinetic information, which is presented here. Blood Halon 1301 levels increased rapidly and approached a steady state within 2 hr of beginning the exposure; the steady-state concentration was approximately 3-4.5 micrograms/ml. Breath samples collected during exposures closely reflected chamber concentrations. Analysis of postexposure blood samples revealed that Halon 1301 was eliminated biphasically with an average t1/2 alpha and t1/2 beta of 4.5 min (range 2.5-8.1 min) and 200 min (range 131-347 min), respectively. Halon 1301 concentrations in fat and soft tissues were also estimated. Subsequently, the end-tidal breath/blood/tissue/fat partition coefficients were calculated to be 17/1/0.5/33.(ABSTRACT TRUNCATED AT 250 WORDS)

Performance and physiological measurements were obtained from four pairs of men exposed for 24 hr to 1% (10,000 ppm) Halon 1301 (bromotrifluoromethane, CBrF3) and to air with order counterbalanced using a double-blind protocol. Cognitive and motor performance was assessed before, during, and after the exposures using seven scales of the Automated Portable Testing System, which produced 13 measures of performance. Halon inhalation induced decrements in 2 of the 13 measures, but actual and estimated magnitudes of the decrements were no greater than 5% of baseline values. Physiological data were obtained before, during, and after the exposures from clinical chemistry analyses of blood and urine samples, pulmonary function tests, and monitoring of vital signs. Significant change during Halon inhalation was observed for 6 of the 52 variables assessed; however, all physiological values remained within clinically acceptable limits. No cardiovascular effects were noted. This study demonstrated that exposure to 1% Halon 1301 for 24 hr can produce minor disturbance of central nervous system function as assessed by cognitive tasks.

Bromochlorodifluoromethane (halon 1211, a fire extinguisher), like other fluorocarbons, has been linked with ventricular arrhythmias and myocardial depression. Ten healthy firefighters, aged 40-50, were exposed to 1,000 ppm halon while exercising, in a double-blind, placebo-controlled crossover experiment, and were monitored during and after exposure. Complex ectopy (ventricular couplets and idioventricular rhythm) occurred in two subjects with halon, but none with placebo. One subject had 49.5 ventricular premature beats (VPB)/hour during the period of halon exposure and subsequent 8 hours and only 8.7 VPB/hour during the same period of placebo. In addition, 8 of the 10 subjects had a smaller systolic blood pressure rise during exercise with halon than with placebo. None of the observed differences was statistically significant. These results are consistent with findings in other investigations, suggesting that occupational fluorocarbon exposures may be cardiotoxic in certain individuals, although the small sample sizes used in this and other studies have resulted in limited statistical power to demonstrate this effect.

Reaction enthalpies and barrier heights of the reactions CF3Br+H--CF3+HBr {reaction (1)} and CF3CHFCF3+H--CF3CFCF3+H2 {reaction (2)} have been calculated at the near state-of-the-art ab initio level, and also by employing the B3LYP, BHHLYP, BB1K, MPW1K, MPWB1K and TPSS1KCIS functionals. In addition, the integrated molecular orbital+molecular orbital (IMOMO) method has been used to study reaction (2). The ab initio benchmark values of the reaction enthalpy (298 K) and barrier height (0 K) of reaction (2) are reported for the first time {-(0.7+/-0.7) and 13.3+/-0.5 kcal/mole respectively}. When density functional theory (DFT) results are compared with ab initio benchmarks for both reactions (1) and (2), the MPWB1K functional is found to have the best performance of the six functionals used. The IMOMO method with the RCCSD/aug-cc-pVTZ and/or RCCSD(T)/aug-cc-pVTZ levels, as the high levels of calculation on the model system, gives reaction enthalpies and barrier heights of reaction (2), which agree with ab initio benchmark values to within 1 kcal/mole. Computed key geometrical parameters and imaginary vibrational frequencies of the transition state structures of reactions (1) and (2) obtained at different levels of calculation are compared. The magnitudes of the computed imaginary vibrational frequencies of the transition states of both reactions considered are found to be very sensitive to the levels of calculation used to obtain them. The heat of formation (298 K) of CF3CFCF3 calculated at the near state-of-the-art level has a value of -(318+/-3) kcal/mole.

A gas chromatographic method with mass spectrometry has been developed for the determination of bromochlorodifluoromethane (Halon 1211) in biological material (whole blood, organ samples). After incubation of the sample (temp. 65 degrees C, 15 min), 10 microliters of the headspace is analysed using a capillary column DB-5 ms (30 m x 0.25 mm x 0.25 micron). Quantitative analysis was made with the use of a single ion monitoring option--m/z 85 and m/z 87. This developed method was used to determine the concentration of bromochlorodifluoromethane in biological material collected from the body of the man whose death was due to intoxication of Halon 1211--fire-extinguisher contents.

Halon 1301 and Halon 1211 are being replaced because they contribute to the depletion of ozone. Many of the potential candidate chemicals for replacing them are, like them, halogenated hydrocarbons. These chemicals have the potential to cause cardiac sensitization at high enough exposure concentrations.A physiologically based pharmacokinetic model, which mathematically describes the uptake, distribution, metabolism, and elimination of chemicals, was used to relate exposure to these chemicals with arterial blood concentrations resulting from the exposure. This information was then used to evaluate the potential for the occurrence of a cardiac-sensitizing event. The model was used to analyze the exposures to Halon 1301 and Halon 1211 in three aircraft (Navy E-2B, Cessna-421B, and Cessna-210C).Halon 1301 exposures were shown to be safe, but Halon 1211 resulted in arterial concentrations in exposed individuals that reached levels that could potentially cause cardiac sensitization.Use of the model for evaluating the risk from exposure to Halon 1301 and Halon 1211 is a moot point since both chemicals are being replaced. However, demonstration of the validity of the approach provides a tool for the evaluation of the health safety of replacement candidates. The National Fire Protection Association has approved use of this model for assessing times for safe egress from situations where agents are used to flood an area to extinguish a fire.

The chemical risk assessment process and the need for health-based approaches to identify and characterize potential hazardous substances will be discussed. The risk assessment process can be applied to both workplace and environmental settings. Toxicology will be defined and related to the risk assessment process. A brief overview of toxicity screens and tests will be presented in order to help make toxicity data more meaningful. Toxicity data for Halon 1301 replacements and trichloroethylene (TCE) will be presented as examples. The paper will conclude with a description of tri-service toxicology; what it is and what this laboratory provides to the Department of Defense (DOD), industry, and academia.

The Pd on Al2O3 catalyst used in the projected Space Station's Trace Contaminant Control System (TCCS) catalytic oxidizer can be poisoned by volatile halogen-, sulfur-, and nitrogen-containing organic species. Catalytically Active Regenerable Sorbents (CARS) eliminate these problematic contaminants and the large carbon bed used for their elimination in a three-step process. Contaminants are conventionally adsorbed by the CARS bed. After saturation, the bed is connected to an off-line recirculation loop, filled with hydrogen, and then heated. At temperature, contaminants are hydrogenated on catalytic sites within the bed, forming simple alkanes and acid gases that are efficiently converted to innocuous salts in an in-line alkaline bed. The CARS bed is regenerated by this cycle and alkane gases are released to be safely oxidized in the catalytic oxidizer. A challenge mixture containing Freon-113, thiophene, trichloroethylene, Halon-1301, and dichloromethane at 1670, 75, 81, 68, and 83 mg/m3 was successfully treated using this technology, demonstrating the CARS feasibility.

Experimental data from the literature for cross sections and rate constants for dissociative electron attachment to CF(3)Br, with separately varied electron and gas temperatures, are analyzed by a kinetic modeling approach. The analysis suggests that electronic and nuclear contributions to the rate constants can be roughly separated, the former leading to a negative temperature coefficient, the latter to a positive temperature coefficient. The nuclear factor in the rate constant is found to be of Arrhenius form with an activation energy which is close to the energy of crossing of the CF(3)Br and CF(3)Br(-) potential curves along the CBr bond.

An accidental discharge of a Halon 1301 system is reported. Thirty-one workers were assessed, 22 who were present at the time of the discharge, and 9 who worked the next shift. The incident was complicated by a small Freon-22 leak several hours later. Throat, eye, and nasal irritation and lightheadedness were reported by the majority of workers. Workers present during the halon discharge reported significantly more lightheadedness, headache, voice change, cough, and a fast heartbeat than did those who worked the later shift. These differences were significant even after correcting for confounding factors such as age, sex, and sense of anxiety at the time of the incident. The possible causes for the irritant symptoms include breakdown products of Halon 1301 and Freon-22 or contaminants from the halon discharge system. Although these irritant effects may not be an effect of Halon 1301 alone, they may occur in these discharge situations, and workers should be advised of this possibility. The possible cardiac and central nervous system effects also should be considered. The importance of a clear-cut protocol to deal with such incidents as well as worker education are discussed.

In the experiments with white rats it was found, that the inhalation of freon 114B2 at CL16, CL50, CL84 levels caused the changes in seasonal values of the energy activity in mitochondria. The action of the freon 114B2 caused disturbances in regulation of the mitochondria activity and desynchronization of seasonal rhythms of their energy activity.

Bromochlorodifluoromethane (Halon 1211) is a widely used fire extinguishing agent. Several cases of sudden death in teenagers associated with BCF abuse have been reported. BCF is used as a fire extinguisher in battle tanks. Two young previously healthy male soldiers were accidentally exposed to BCF in a battle tank. The tank driver died, but the gunner survived the event with no medical complications. It is concluded that BCF should be used in confined chambers only after the evacuation of all personnel.

This report describes the case of a 43-yr-old male who developed reactive airways dysfunction syndrome after exposure to a high level of bromotrifluoromethane (CF3Br, Halon 1301), a fluorocarbon widely used in automatic fire extinguishing systems. The patient was a previously healthy, nonatopic male, who developed wheezing and intermittent and reversible obstructive ventilatory impairment starting immediately after a large accidental nonfire-related release of CF3Br in a confined space.

Constatation d'une deperdition inquietante en ozone stratospherique, mesuree notamment au-dessus de l'Antarctique, depassant de beaucoup les previsions. Facteurs responsables. Consequences previsibles: manque d'absorption des UV, risques accrus de cancer. Autres consequences difficiles a prevoir. Avenir incertain

The effect of bromochlorodifluoromethane (BCF) on reproduction in the rat has been investigated in two studies. Pregnant female rats were exposed by inhalation to 1000, 10,000, or 50,000 ppm BCF for six hours a day on days six to 15 of gestation (day of mating = day 0). Exposure to 50,000 ppm BCF caused a reduction in maternal weight gain over the exposure period but there was no evidence of either teratogenicity or embryo/fetotoxicity at any concentration. In a study designed to assess the potential effect of BCF during a complete reproductive cycle male and female rats were exposed to 5000 ppm or 25,000 ppm BCF for six hours a day for five days a week for 10 weeks (males) or three weeks (females) before mating. Exposure to BCF continued during mating and up to day 20 of gestation for half the females which were subsequently allowed to litter and the development of their offspring monitored. The remaining females were removed from exposure to BCF after mating and killed on day 20 of gestation for examination of their uterine contents. There were no effects on adult fertility, pup numbers, survival, or pup development. It was concluded that BCF had no reproductive toxicity potential in the rat.

This review sums up the results of the examinations concerning the toxicity of the fire extinguishing agents Bromotrifluoromethane and Bromochlorodifluoromethane. Besides the toxicity of the pure substances decomposition products are subject to this paper.

The halocarbon BCF was tested in 3 assays to assess its mutagenicity and clastogenicity. It produced a positive response in Salmonella typhimurium strain TA1535 but was negative in TA1537, TA1538, TA98 and TA100. In an L5178Y mouse lymphoma microwell assay (TK locus), BCF was negative. BCF was administered at 5000 and 50 000 ppm in air for 6 h to groups of C57B1/6J mice of both sexes. Animals were killed at 24, 48 and 72 h after cessation of exposure and the incidence of bone marrow micronuclei per 1000 PCEs determined. There was no significant difference in the incidences of micronuclei between untreated animals and those exposed to either concentration of BCF at any of the sampling times. These results suggest that BCF is mutagenic in vitro in only one strain of Salmonella; in mammalian cells the compound induced no gene mutation in vitro nor clastogenic activity in vivo at doses that also produced clear evidence of toxicity.