ENVIRONMENTAL SCIENCE & TECHNOLOGY; 33 (11). 1892-1897.
wave plasma abatement of CHF3 and CF4 containing semiconductor
BA JACKSON MW HARTZ C BEVAN JW
Department of Chemistry,
Texas A and M University, College Station, TX, 77843-3255, USA.
exponential growth in semiconductor device manufacture over the
next few years demands technology to reduce the corresponding
increase in etchants such as perfluorocompounds (PFCs), CHF3,
and SF6 that would be emitted into the atmosphere. These compounds
are a cause for concern because of their large global warming
potentials relative to CO2 and of their long lifetimes in the
atmosphere, often tens of thousands of years. We demonstrate that
a plasma-based technology can yield effective rom 500 to 1950
W were investigated and DREs for CF4
and CHF3 reported. Final product analysis indicated that PFC conversion
was limited to low molecular weight gases such as CO2, CO, COF2,
H2O, and HF. These investigations demonstrate that surface wave
plasma destruction of the referenced PFCs at the output of semiconductor
etch tools is a viable nonintrusive point of use abatement technology.
CLIMATIC CHANGE; 42 (4). 633-662.
for estimating future emissions of sulfur hexafluoride and perfluorocarbons.
DG MACDONALD GJ
Council on Foreign
Relations, 58 E. 68th Street, New York, NY, 10021, USA.
Abstract: Sulfur hexafluoride
(SF6), perfluoromethane (CF4) and
perfluoroethane (C2F6) are strong greenhouse gases with long (>1000
year) atmospheric residence times. We derive emission factors
for the major anthropogenic sources and project future emissions
for 5 regions and the world. Although firms in many industrialized
countries are already limiting emissions, without further policy
intervention global emissions will rise 150% (CF4 and C2F6) and
210% (SF6) between 1990 and 2050; radiative forcing wil he 1997
Kyoto Protocol, which includes commitments for industrialized
countries to regulate these and other greenhouse gases. More complete
and transparent data are urgently needed. West European nations,
for example, can 'cut' their
emissions of these gases by half by 2010 simply by manipulating
emission factors within the current bounds of uncertainty.
ENVIRONMENTAL SCIENCE & TECHNOLOGY; 32 (20). 3237-3240.
Arc process for treatment of CF4 emissions.
DT DAVID MM TIERS G VD SCHROEPFER JN
and Environ. Safety Div., 3M Cent., Build. 260-3B-08, St. Paul,
MN 55144-1000, USA.
Abstract: BIOSIS COPYRIGHT:
BIOL ABS. Light perfluorocarbons, such as carbon
tetrafluoride, are produced or emitted from a variety of processes,
including manufacture of aluminum and processing of semiconductor
devices. At the same time, the long atmospheric lifetime
and high global warming potential of such compounds makes them
an environmental concern. A new process for the abatement of perfluorocarbon
emissions using a carbon arc plasma was investigated. In particular,
the conversion of CF4 to C2F4 and higher fluorinated species,
including poly(tetrafluoroethylene) (PTFE) was demonstrated, General
features of the reaction chemistry are discussed, including primary
reactions to form radicals and ions and secondary reactions to
form C2F4 and higher compounds.
The conversion efficiencies and products obtained in the reported
experiments indicate potential applicability of the process for
point source emission control of high global warming potential
AMBIO; 27 (3). 187-197.
greenhouse effect and global warming: Underlying principles and
outstanding issues: Volvo Environmental Prize Lecture 1997.
Cent. Clouds Chem.
Climate, Scripps Inst. Oceanography, Univ. Calif. San Diego, 9500
Gilman Drive, La Jolla, CA 92093-0221, USA.
Abstract: BIOSIS COPYRIGHT:
BIOL ABS. This paper describes the developments that transformed
the global warming problem from that arising solely from CO2 increase
to the trace-gas greenhouse effect problem in which several non-CO2
gases, CFCs, CH4, N20, O3 and others
contribute as much as CO2. Observed trace-gas increases, including
CO2 increase, since the mid-19th century have enhanced the atmospheric
greenhouse effect, Ga, ( 130 | 5 W m-2) by about 2%. Without other
competing factors, this heating should have committed the planet
to a warming of about 1 to 1.5 K. The added radiative energy is
maximum in the low latitudes and about a factor of two smaller
in the polar regions. The largest effect of the warming is increased
back radiation at the surface by as much as 6 to 8 W m-2 per degree
warming. Not all of this increased energy is balanced by surface
emission; evaporation (and hence precipitation) increases to restore
surface energy balance, by as much as 2 to 4% per degree warming.
The increase in eva
IN VITRO TOXICOLOGY; 10 (4). 455-457.
toxicity of CF3X halocarbons.
WS, ROSZAK S, KAUFMAN JJ, BALASUBRAMANIAN K
Dep. Chem., Johns Hopkins
Univ., 3400 N. Charles St., Baltimore, MD 21218, USA.
Abstract: A molecular
model for the carcinogenicity of carbon
tetrachloride in mice has been previously suggested in
which an electron is transferred from an enzyme to the CCl4 molecule
resulting in its dissociation into Cl- and the free radical CCl3.
Cellular damage was attributed to the free radical. In light of
this model, we examined the series of one carbon halocarbons CF4,
CF3Cl, CF3Br, and CF3I for their potential carcinogenic activity.
The propensities of the halocarbons to produce free radicals by
dissociative electron attachment were obtained by quantum chemical
calculations or by physical measurements. The ability of the free
radicals to abstract hydrogen atoms from the lipid was estimated
from C-H bond energies in the appropriate molecules formed when
the free radical combines with the hydrogen atom. Using these
two parameters the potential toxicity of the halocarbons was established.
In Vitro Toxicology. A Journal of Molecular and Cellular
Toxicology,Vol. 10, No. 4, pages 455-457, 7 references
Toxicity of CF(3)X Halocarbons
WS, Roszak S, Kaufman JJ, Balasubramanian K
Abstract: The potential
carcinogenic activity of the series of one carbon halocarbons
carbon-tetrafluoride (75730) (CF4),
chlorotrifluoromethane (75729) (CF3Cl), bromotrifluoromethane
(75638) (CF3Br), and iodotrifluoromethane (CF3I) was studied in
response to recent research examining whether CF3I is a less toxic
combustion inhibitor than CF3Br which has been widely used in
fire extinguishers on aircraft. The toxicity of this series of
halocarbons was assessed in light of a molecular model for the
carcinogenic effects of carbon-tetrachloride (56235) which suggests
that cellular damage results from free radicals produced following
the transfer of an electron from an enzyme to the carbon-tetrachloride
molecule. The carcinogenic activity of the halocarbon series was
studied by calculating the vertical electron affinities (VEA)
of the various molecules using quantum chemical calculations or
physical measurements. Based on experimentally determined and
calculated VEA values, CF4 was considered nontoxic on the basis
of the free radical model, CF3Cl was considered equivocal, CF3Br
was considered toxic, and CF3I was considered to be carcinogenic.
In many cases, the toxicity of the halocarbons increased with
their efficacy as combustion inhibitors.
CLIMATIC CHANGE; 34 (3-4). 405-437.
of indirect global warming potentials for CH4,
CO and NOx.
JS, ISAKSEN I SA, WANG W-C
Cent. Int. Climate
Environ. Res., Univ. Oslo, PO Box 1129, Blindern, N-0317 Oslo,
may affect climate indirectly through chemical interactions in
the atmosphere, but quantifications of such effects are difficult
and uncertain due to incomplete knowledge and inadequate methods.
A preliminary assessment of the climatic impact of changes in
tropospheric O3 and CH4 in response to various emissions is given.
For a 10% increase in the CH4 emissions the relative increase
in concentration has been estimated to be 37% larger. The radiative
forcing from enhanced levels of tropospheric O3 is estimated to
37% of the forcing from changes in CH4. Inclusion of indirect
effects approximately doubles the climatic impact of CH4 emissions.
Emissions of NOx increase tropospheric O3, while the levels of
CH4 are reduced. For emissions of NOx from aircraft, the positive
effects via O3 changes are significantly larger than the negative
through changes in CH4. For NOx emitted from surface sources,
the effects through changes in O3 and CH4 are estimated to be
of sim [abstract truncated]
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL; 2 (3).
production as a source of atmospheric carbonyl sulfide (COS).
J, BORCHERS R, FABIAN P, KOURTIDIS K
PO Box 20, D-37189 Kaltenburg-Lindau, Germany.
sulfide is found as a major sulfur compound in anodic gases of
commercial aluminium electrolysis. Recent spectroscopic measurements
on industrial aluminium smelters found typical CO ratios between
80 and 200. This results in specific COS emissions of between
1 and 7 kg/t(Al) if all COS is released into the atmosphere. In
1993 aluminium production would have been responsible for between
0.02 and 0.14 Tg of COS emissions. Currently, aluminium production
does not seem to influence the total atmospheric COS budget to
an extent beyond its natural variability. If recent growth rates
of global aluminium production are sustained, however, COS emissions
would quadruple until 2030. Together with increasing aircraft
emissions into the stratosphere, an increase of the sulfate background
aerosol is to be expected that could significantly enhance ozone
depletion. The use of inert anodes is recommended to reduce aluminium
production emissions of COS and CF4,
C2F6, CO2 and CO
MEDITSINA TRUDA I PROMYSHLENNAYA EKOLOGIYA; 0 (8). 5-8.
to regulate aerosol of carbon fluoride fibers in the air of workplace.
NA, VELICHKOVSKII BT, GREKHOVA TD, ZYKOVA VA, EL'NICHNYKH LN
Med. Sci. Cent. Prev.
Med. Prot. Health Ind. Work., Ekaterinburg, Russia.
studies were conducted by means of pilot industrial plant for
production of carbon tetrafluoride fibers
(CTF). The studies proved that the main hazards of the
production are CTF dust and hydrogen fluoride. Average shift concentrations
of MT dust in the air of workplace equal 0.6-1.5 mg/cu m which
2 times higher than the MAC for HP at all technologic sites except
for reactor compartment. The workers servicing the plant demonstrate
higher urinary fluor excretion mostly due to HP intake. Experimental
studies showed that CTF have low cytotoxicity and fibrogenic activity,
these chemicals are assigned to IV jeopardy class (mild hazards).
If applied on skin, CTF are absorbed and induce slight local irritation.
The MAC for CTF in the air of workplace is set at 6 mg/cu m.
SCIENCE (WASHINGTON D C); 259 (5092). 194-199.
lifetimes of long-lived halogenated species.
RAVISHANKARA AR, SOLOMON S, TURNIPSEED AA, WARREN RF
Natl. Oceanic Atmospheric
Adm. Aeronomy Lab., Boulder, CO 80303, USA.
Abstract: The atmospheric
lifetimes of the fluorinated gases CF4,
C2F6, c-C4F8, (CF3)2c-C4F6, C5F12, C6F14, C2F5Cl, C2F4Cl2, CF3Cl,
and SF6 are of concern because of the effects that these long-lived
compounds acting as greenhouse gases can have on global climate.
The possible atmospheric loss processes of these gases were assessed
by determining the rate coefficients for the reactions of these
gases with O(1D), H, and OH and the absorption cross sections
at 121.6 nanometers in the laboratory and using these data as
input to a two-dimensional atmospheric model. The lifetimes of
all the studied perfluoro compounds are >2000 years, and those
of CF3Cl, CF3CF2Cl, and CF2ClCF2Cl are >300 years. If released
into the atmosphere, these molecules will accumulate and their
effects with persist for centuries or millennia.
(PHILADELPHIA); 8 (3). 519-531.
FUME FEVER AND OTHER FLUOROCARBON PYROLYSIS-RELATED SYNDROMES
Abstract: BIOSIS COPYRIGHT:
BIOL ABS. RRM LITERATURE REVIEW HUMAN OCCUPATIONAL HEALTH EPIDEMIOLOGY
of the European Communities, 2985 Luxembourg, Grand Duchy of Luxembourg;
International Programme on Chemical Safety (IPCS), World Health
Organization, 1211 Geneva 27, Switzerland, 1993.
chemical safety card. Short term exposure effects: risk of suffocation
in confined areas; frostbite.
Registry Numbers: 75-73-0
Clean Air at Work, New Trends in Assessment and Measurement for
the 1990s, Proceedings of an International Symposium, Luxembourg,
9-13 September 1991, R. H. Brown, M. Curtis, K. J. Saunders and
S. Vandendriessche, Editors; -=Royal Society of
of Fourier Transform Infrared Remote Sensing to Air Quality Monitoring
in the Workplace
Brandon RW, Trautwein J Jr
Abstract: The use
of Fourier Transform Infrared remote sensing (FTIR) for monitoring
air quality in various workplaces was discussed. The basic principles
of FTIR/RS were summarized. Application of FTIR/RS to a medium
sized electronics assembly area where a cleaning solvent and an
aerosol propellant were present at low concentrations and an aluminum
smelter was discussed as examples of its use. Methanol (67561)
and Freon-12 (75718) vapors were detected in the electronics assembly
area at concentrations of 0.135 and 2.107 parts per million (ppm),
respectively. Hydrogen-fluoride (7664393) at a concentration of
5ppm was detected in the aluminum smelter. Carbon-tetrafluoride
(75730), carbon-monoxide (630080), carbonyl-sulfide (463581),
ammonia (7664417), and silicon-tetrafluoride (7783611) were also
Instituto Nacional de Seguridad e Higiene en el Trabajo, Ediciones
y Publicaciones, correlaguna 73, 28027 Madrid, Spain, 2p.
Abstract: Spanish version
of IPCS ICSC 8-0575. International Chemical Safety Card. Synonym:
tetrafluoromethane. Short-term exposure effects: risk of suffocation
in confined areas; frostbite.
Z GESAMTE HYG GRENZGEB; 37 (2). 58-63.
air pollutants emitted by the production of integrated circuits:
Strategy and results.
PONSOLD B, KATH H
Author Address: Leiter
der Staatlichen Umweltinspektion Erfurt, PSF 652, O-5010 Erfurt.
Abstract: BIOSIS COPYRIGHT:
BIOL ABS. A four-month study of pollutants emitted during the
manufacture of integrated circuits yielded the following results:
The emission limit for hydrogen chloride is maintained in normal
operations; there is no danger in the exposure area. The limit
for nitrogen oxides is exceeded, but there are no harmful consequences.
Ammonium, for which there was no limit value, causes no negative
effects at the concentrations measured. The limit values for silane
and phosphine are exceeded; a negative influence is possible in
the exposure area. Long-term accumulation of arsenic in the exposure
area should be monitored further. Ozone, hydrogen fluoride, and
hydrogen chloride, produced during the fine purification process,
are largely eliminated by secondary reactions in the exhaust air
exhaust system. Results are also reported for chlorofluorocarbons
hexafluoroethane, dichlorodifluoromethane, and chlorodifluoromethane)
and organochlorine compounds re
Biochemical Pharmacology, Vol. 39, No. 5, pages 833-840,
of Metallothionein-Carbon Tetrachloride Interaction In Vitro
Suntres ZE, Lui EMK
Abstract: The biochemical
basis for the protective role of metallothionein (MT) in carbon-tetrachloride
(75730) (CCl4) toxicity was examined in male Sprague-Dawley-rats.
Experiments were designed to characterize the reaction between
CCl4 or its metabolite(s) and cadmium, zinc metallothionein-II
(Cd,Zn-MT-II), concentrating primarily on MT thiols as potential
sites for interaction. A time dependent depletion of MT thiols
with a concurrent reduction in the metal binding sites of the
protein was noted on incubation of Cd,Zn-MT-II with CCl4 in the
presence of hepatic microsomes and NADPH. Zinc and cadmium were
also released from MT by this reaction. The trichloromethyl radical,
chloroform and phosgene as well as the product of CCl4 induced
microsomal lipid peroxidation were not directly involved in the
CCl4 induced decrease in MT thiol content. Covalent binding of
CCl4 to MT was noted after incubation in the presence of a microsomal
bioactivation system, but it did not account for the CCl4 induced
loss of MT thiol groups. The results suggested that CCl4 induced
oxidation of MT rather than the covalent
binding of CCl4 metabolite(s) was responsible for the CCl4 induced
loss of metal biding sites of Cd,Zn-MT with the concurrent release
of zinc and cadmium. The authors conclude that the precise role
of the metal released during the oxidation of MT in CCl4 toxicity
remains to be clarified.
Handbook of Toxicology, T. J. Haley and W. O. Berndt, Editors;
Hemisphere Publishing Corporation, pages 472-503, 172 references
Abstract: Studies into
the effects of and accidental exposures to asphyxiant gases occurring
in occupational settings are reviewed. Such exposures occur in
manufacturing industries, chemical processing facilities, or in
any number of secondary situations where chemicals are used on
the job. A gas may be only an irritant, or it may affect cellular
metabolism or stimulate antibody production. Specific gases discussed
include ammonia (7664417), which causes edema of the respiratory
tract, spasms of the glottis, and asphyxia; carbon-monoxide (630080),
which combines with myoglobin and hemoglobin in competition with
oxygen resulting in asphyxiation; and ethylene-oxide (75218),
which is an eye, nose and throat irritant and may cause coughing
and vomiting along with pulmonary edema at high concentrations.
Ethylene-oxide is also considered a possible carcinogen. Also
mentioned are various fluorocarbons including carbon-tetrafluoride
(75730), cryofluorane (1320372), dichlorodifluoromethane
(75718), and trichlorofluoromethane (75694). Formaldehyde (50000)
at low concentrations produces eye irritation, respiratory tract
irritation, headache, and tiredness. Hydrogen-cyanide (74908)
is extremely poisonous and rapid acting with death occurring within
minutes from respiratory failure. The cyanide reacts with the
trivalent iron of cytochrome-oxidase in mitochondria, blocking
the reduction of oxygen and resulting in cytotoxic hypoxia. This
occurs through blocking of the transfer of electrons from cytochrome-oxidase
to oxygen. Hydrogen-sulfide (7783064), inhaled in concentrations
of 1000 to 2000 parts per million, causes immediate loss of consciousness
and almost immediate death. Isocyanates induce hypersensitivity
and asthmatic reactions with symptoms of shortness of breath,
wheezing, cyanosis, and dermal reactions. Nitrogen-dioxide (10102440),
nitrous-oxide (10024972), and sulfur-dioxide (7446095) are also
NATURE (LOND); 277 (5697).
OF CARBON TETRA FLUORIDE IN THE ATMOSPHERE
RASMASSEN RA, PENKETT SA, PROSSER N
Applied Ecology Department, Research Triangle Institute,
Research Triangle Park, North Carolina, Contract No. 210-76-0142,
541 pages, 702 references
Process, and Use Data for In-House Criteria Document Part 4 Flourocarbons
of currently available literature pertinent to fluorocarbons.
Information is selected and documented relative to industrial
use (standard industrial classification); industrial processes,
operations, and equipment; and engineering controls and personal
protection. The report includes general information on fluorocarbons
and fluorocarbon polymers, data regarding uses and processes involving
fluorocarbons, and information on fluorocarbons that may present
industrial hazards, including poisoning by freon (75456), carbon-tetrafluoride
(75730), carbonyl-fluoride (353504), chlorodifluoromethane
(75456), bromotrifluoromethane (75638), dichlorotetrafluoroethane
(1320372), fluoroacetic-acid (144490), hexafluoroacetone, (684162),
sodium-fluoroacetate, teflon (9002840), 1,1,2,2-tetrachloro-1,2-difluoroethane,
and 1,2-trichloro-1,2,2-trifluoroethane. (Contract No 210-76-0142)
to Carbon tetrafluoride Index Page