WASHINGTON OPERATIONS,
MTR-7144
flir Pollution flssessment
of Carbon Tetrachloride
RICHARD JOHNS
FEBRUARY 1976
TIUl
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MITRE Technical Report
MTR-7144
flir Pollution flssessment
of Carbon letractilonde
RICHARD JOHNS
FEBRUARY 1976
CONTRACT SPONSOR ' Environmental Protection Agency
CONTRACT NO. 68-02-1495
PROJECT NO. 077B
OEPT. W-54
THEE
MITRE
This aocurnent was D,eoa,ea IQ, autnonzco distribution
McLEAN, VIRGINIA 22101 it nas not oeen aoorovea lor public release
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Department Approval.
MITRE Project Approval:
1 V /
^ JfJt-
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ABSTRACT
This report concerns the organochlorine solvent carbon
tetrochloride, which is used primarily in the manufacture of
fluorocarbons. The toxic effects of the solvent in both animals
and man are discussed and the probability of those effects
occurring at the ambient atmospheric concentrations to which
the general population is exposed is assessed. Methods for
atmospheric sampling of carbon tetrachloride and available
control technology for the prevention of release to the
environment are also discussed.
iii
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ACKNOWLEDGEMENTS
The author gratefully acknowledges the assistance of L. Duncan
in the derivation of downwind concentration estimates for carbon
tetrachloride sources. He is also indebted to B. Baratz, J. Golden,
R. Ouellette, L. Thomas, and V. Wenk for their critical review and
comment, and to R. Johnson and J. Manning of the U.S. Environmental
Protection Agency for their many helpful suggestions.
iv
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TABLE OF CONTENTS
Page
I. SUMMARY AND CONCLUSIONS 1
II. AIR POLLUTION ASSESSMENT REPORT 6
A. PHYSICAL AND CHEMICAL PROPERTIES 6
B. EFFECTS 9
C. AMBIENT CONCENTRATIONS, POPULATION AT RISK AND
MEASUREMENT TECHNOLOGY 16
D. SOURCES 21
E. CONTROL STRATEGY 27
REFERENCES 29
LIST OF FIGURES
FIGURE NUMBER Page
1 CARBON TETRACHLORIDE PRODUCTION CAPACITY 22
2 CARBON TETRACHLORIDE - COMMERCIAL PATHWAYS 25
LIST OF TABLES
TABLE NUMBER Page
I CARBON TETRACHLORIDE - PHYSICAL PROPERTIES 7
II ACUTE TOXICITY OF CARBON TETRACHLORIDE 10
III TYPICAL CONCENTRATIONS OF CARBON TETRA-
CHLORIDE IN THE ENVIRONMENT 13
IV OBSERVED CARBON TETRACHLORIDE CONCENTRATIONS
IN FOODSTUFFS 14
V CARBON TETRACHLORIDE PRODUCTION DATA 23
VI CARBON TETRACHLORIDE COMMERCIAL PATHWAYS 26
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I. SUMMARY AND CONCLUSIONS
Carbon tetrachloride is a colorless, nonflammable liquid, pos-
sessing excellent solvent properties for fats, oils, plastics and
many organic chemicals. It is not highly reactive and is neither
oxidized readily in air nor hydrolyzed rapidly in water. The chemical
is decomposed to toxic products such as hydrogen chloride and phosgene
on contact with hot metal. It is estimated to have a half-life of 10
to 33 weeks toward atmospheric photodegradation. An octanol/water
distribution coefficient of 2.64 indicates a mild tendency for carbon
tetrachloride accumulation in body lipids.
Depending upon the organism and route of administration, certain
concentrations of carbon tetrachloride result in toxic, carcinogenic,
or mutagenic activity in mammals, the liver being the primary center
of damage. Hepatotoxicity of the compound is enhanced by certain
dietary factors, particularly alcohol ingestion. The chemical is ab-
sorbed through the lungs and from the gastrointestinal tract, but only
marginally through the skin. Carcinogenic studies using laboratory
animals have shown tumors of the liver to result from repeated oral and
subcutaneous administration of the chemical. The appearance of hepatomas
in man, several years after carbon tetrachloride poisoning, has been
reported in several cases. Several biochemical indices have been
developed recently which forewarn of clinical symptoms of chronic
exposure to carbon tetrachloride. The American Conference of Govern-
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mental Industrial Hygienists has recommended a threshold limit
value of 65 mg/m (10 ppm), which has been adopted by the Occupational
Safety and Health Administration (OSHA) as a maximum 8-hour-average
level for workplace atmospheres. The odor threshold of carbon tetra-
chloride is about 500 mg/m3 and, hence, is entirely inadequate as a
signal of danger.
Ambient data on localized carbon tetrachloride concentrations
are sparse; hence, population exposure is not widely assessable from
experimental data. A study in the Los Angeles Basin revealed an
atmospheric concentration range of 1 to 2 yg/m^ over 54 ground-level
stations, with an excursion to 10 yg/m3 at one site. Analytical
measurements were made using a gas chromatograph equ_pped with an
electron capture detector. This is the method of choice for halo-
hydrocarbons, and is capable of detecting carbon tetrachloride at the
parts-per-billion level.
Exposure over a 75-year lifetime to the 2 yg/m level of carbon
tetrachloride found in the Los Angeles Basin is approximately equiva-
lent to one day's occupational exposure at the OSHA limit of 65 mg/m3.
The atmospheric concentration of the chemical near production facilities
may be estimated with an atmospheric diffusion model. For a typical
carbon tetrachloride plant, an atmospheric concentration of 1.4 mg/m3
at a point 500 meters downwind of the plant is developed. Exposure
to this concentration over a 75-year lifetime ±s equivalent in dose to
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a 7-year occupational exposure at the OSHA limit for workroom atmospheres.
The downwind distance of 500 meters is representative of a location near
the property line of a production facility.
Population exposure may arise from dispersive uses of carbon
tetrachloride, but levels of exposure are unknown. The use of the
product as a fumigant for rodents carries the potential for exposure
of building occupants, neighbors, and bystanders. Solvent use has
declined and carbon tetrachloride is no longer generally available as
a consumer product. The high vapor density of this compound warrants
concern for localized ground-level vapor sinks which may accumulate
hazardous levels of carbon tetrachloride. Such sinks can be envi-
sioned, for example, in basements of buildings undergoing fumigation.
The chemical can enter the environment through various routes.
Losses to the atmosphere are possible in the production, handling,
and distribution of carbon tetrachloride. Dispersive uses of the
chemical contribute further to the atmospheric burden, although they
account for only a small fraction of consumption. Carbon tetrachloride
is ubiquitous in the troposphere, and global studies indicate a natural
occurrence of the compound. At an altitude of 5 to 10 km, the background
2
is typically 0.5 to 1.0 P8/m carbon tetrachloride. From global atmo-
spheric measurements, it can be estimated that the worldwide atmospheric
burden exceeds the total production of carbon tetrachloride during this
century by at least twentyfold, thus indicating the likelihood of a
non-industrial source. The compound has been found in a variety of
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environmental samples at the parts-per-billion level, but no sig-
nificant accumulation in the food chain has been shown.
Carbon tetrachloride is produced at 11 plant sites in th« United
States, largely concentrated in the Gulf Coast area. The compound
ranks as a major industrial chemical, with annual production in excess
of one billion pounds. The bulk of carbon tetrachloride production
(95 percent in 1973) is used in the manufacture of fluorocarbons
(trichlorofluorometliane and dichlorodif luoromethane) ; hence, the
market is highly sensitive to the demand for aerosol products. Demand
grew at a rate of 6.8 percent per year from 1960 to 1970, but has
shown a leveling trend due to slowing growth of aerosol products.
Should the use of fluorocarbon propellant be banned in the future,
demand for carbon tetrachloride could be expected to diminish to about
45 percent of its current level.
Two critical considerations in the air pollution assessment of
carbon tetrachloride are: (1) accumulation of man-made residues of
the chemical in the upper atmosphere, and (2) exposure risk in the
vicinity of sources of the chemical. The latter consideration relates
directly to the health of population groups near sources, whereas the
former concerns the steady-state composition of the troposphere and
attendant health effects. Occupational and consumer exposure to carbon
tetrachloride vapor are not air pollution problems in a strategic
sense.
The evidence for natural sources of carbon tetrachloride implies
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that the relative atmospheric contribution from anthropogenic sources
is minor. Based on available evidence, there appears no need for
additional control of carbon tetrachloride emissions so far as the
total atmospheric sink is concerned.
Measured concentrations of carbon tetrachloride in urban atmo-
spheres, as well as estimated levels near production facilities, are
not significantly greater than the worldwide background of 0.5 to
1.0 yg/m^. These levels are about five orders of magnitude below the
threshold limit value and, hence, pose no probable risk to local
populations near sources.
The risk from dispersive applications of carbon tetrachloride
is difficult to control. The threshold limit value is exceeded by
the evaporation of one milliliter of the solvent into a 3-meter cubi-
cal room.
Carbon tetrachloride and other chlorohydrocarbons are scheduled
for study by the National Institute for Occupational Safety and Health
during 1976. Occupational risk will be the primary focus of this work,
but "fenceline" measurements may be included in the study. A study of
the carcinogenic potential of carbon tetrachloride is in progress at
the National Cancer Institute.
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II. AIR POLLUTION ASSESSMENT REPORT
A. PHYSICAL AND CHEMICAL PROPERTIES
Carbon tetrachloride is a colorless, nonflammable liquid, pos-
sessing excellent solvent properties for fats, oil, plastics, rubber,
and many organic chemicals. The principal physical properties of the
compound are shown in Table I. The chemical shows no oxygen uptake in
the standard BOD test*, nor is it readily decomposed by photodegrada-
tion. Carbon tetrachloride is estimated to have a half-life of 10 to
33 weeks toward atmospheric photodegradation (1). The vapor is decom-
posed above 200°C into hydrogen chloride, chlorine, phosgene and other
products. The production of toxic degradation is enhanced by the
presence of hot metal; hence, the former use of the chemical in small
fire extinguishers has been abandoned. At 250°C, carbon tetrachloride
becomes an active chlorinating agent for oxides of metals such as
aluminum and zinc.
Carbon tetrachloride hydrolyzes very slowly in contact with water,
showing a half-life of 70,000 years at a pH of 1.0 to 7.0. Hydrolysis
is accelerated by the presence of iron, zinc, and other metals. The
chemical is inert to strong acids, but is decomposed by strong alcholic
alkali or strong bases to simple inorganic products. An octanol/water
partition coefficient** of 2.64 (Table I) indicates a mild tendency
*Biochemical Oxygen Demand. A measurement of oxygen consumption
during controlled biochemical degradation.
**A partition coefficient expresses the equilibrium concentration
ratio of a solute between two phases which are in mutual contact.
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TABLE I
CARBON TETRACHLORIDE
Physical Properties
Chemical Formula
Molecular Weight
Boiling Point
Melting Point
Vapor Pressure, 25°C
Specific gravity, liquid
Specific gravity, vapor vs. air
Refractive Index, 20°C
Solubility, Water
Solubility, Octanol
Partition Coefficient, Octanol/Water
Partition Coefficient, Water/Air, V/V, 20°C
CC1,
153.84
76.9°C
-22.9°C
115.2mm Hg
1.589
5,32
1.4607
0.8 g/1
oo
2.64
1.1
Sources: Kirk, R. E. Encyclopedia of Chemical Technology, Second
Edition. New York, Wiley, 1968.
National Science Foundation Panel on Manufactured Organic
Chemicals, SRI Data, 1975.
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for carbon tetrachloride accumulation in body lipids. Carbon tetra-
chloride snows a water/air partition coefficient of 1.1, expressed
in terms of volume. This indicates that the chemical is slightly
more soluble in air than in an equal volume of water. In terms of
mass, this indicates that the chemical is about 1,000 times more
soluble in air than in water. Reduced to practical considerations,
a body of water swept with air will tend to transfer its carbon tetra-
chloride content to the air phase, which will be the primary medium of
environmental transport.
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B. EFFECTS
Carbon tetrachloride has been shown to be toxic to mammals by a
variety of exposure routes. It is readily absorbed in the mammalian
gastrointestinal tract or lung, while little dermal absorption occurs.
The absorption rate of ingested carbon tetrachloride is greatly af-
fected by the diet; ethanol consumption or high-fat diets will greatly
enhance carbon tetrachloride uptake C2). Any absorbed carbon tetra-
chloride will be metabolized, though rather slowly, in the liver. This
slow rate of degradation is thought to be a primary factor in the tox-
icity of carbon tetrachloride (3). The liver and kidney are usually
the first organs to evidence dysfunction or destruction as a result of
carbon tetrachloride exposure by ingestion or inhalation (2). Because
of the rather slow degradation rate, repeated exposure to carbon tetra-
chloride, even at low doses, becomes significant. The relative acute
toxicity of carbon tetrachloride to selected mammalian species is shown
in Table II, emphasizing variability in terms of species, routes of
administration, and exposure period.
The American Conference of Governmental Industrial Hygenists
CACGIH) has recommended a threshold limit value (TLV)* for carbon
tetrachloride in the workplace of 65 mg/m (10 ppm). The odor thresh-
old of carbon tetrachloride is approximately 500 mg/m^ and, hence,
*The minimum concentration known to produce a physiological response.
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TABLE II
ACUTE TOXICITY OF CARBON TETRACHLORIDE
REFERENCE
7 hr/day; 5 day/wk Adams et_ al, Arch. Ind. Hyg. Occ. Med.
6; 50 (1952)
Spiegel et_ al, AEC Report 0MODC-1715
(1947/48)
Tox. Appl. Pharm. IB; 168 (1971)
Smvth, unpb. dcta, Mellon Institute
McColllster, st_ al, Arch. Lnd. llyg. 13.;
1 (1956)
Muller, Arch. Exp. Path. Pharm. 109;
276 (1925)
J^ Nat. Can. Inst. 30; 837 (1963)
Dybing, Acta pharm 2; 233 (1946)
Rothschild, Hospital 27; 1017 (1945)
Fuhner, Arch. Exp. Path. Pharm. 97;
86 (1923)
Lamson, J_._ Pharm. Exp. Ther. 22; 215
(1923)
Fuhner, op. cit.
Reuss, Thesis, Worzburg (1932)
Cant a row, e£ al. Jj_ Pharm. Exp. Ther.
£3; 153 (1938)
Barsocm e£ al, Qtly. J.. Pharm. ^; 205 (1935)
Lamson, op. cit.
Barsoom, op. cit.
Elklns, Chem. of Ind. Tox. 2nd Ed., Wiley
N.Y.
Amer. Pest Cent.. Inc.. Kansas, (1966)
Inhal. - Inhallatlon
SC - subcutaneous
IV - Intravenous
LC - lethal concentration
LD - lethal dose
MLD - minimum lethal dose
MLC - minimum lethal concentration
LC50 - concentration lethal to 50 percent of a sample population under staled experimental conditions.
LDj0 - dose fatal to 50 percent of a sample population under stated experimental conditions.
ANIMAL
Rat
Mouse
Hamster
Rjbbit
Cat
Dog
Human
ROUTE
Inhal.
Inhal.
Inhal.
Ural
Oral
Inhal.
Oral
Oral
SC
Oral
Oral
Oral
Inhal.
SC
Oral
Oral
IV
Inhal.
Inhal.
DOSE
LC50
MLC
LC50
LD50
LDlo
MLC
MLD
LD50
LD
LD100
MLD
LD
LD
MLC
LD33
MLD
LD
MLD
MLC
MLC
LENGTH OF
DOSAGE EXPOSURE
2515 mg/m3 7 hr/day; 5 di
150 g/m3 30 min:
50 g/m3 4 hr.
7460 rag/kg
2920 mg/kg
51 g/m3 104 min.
6000 mg/kg
12 BOO mg/kg
3554 mg/kg
320 mg/kg
6380-9975 mg/kg
900-10.700 mg/kg
90 g/m3 70 min.
4785 mg/kg
4000 mg/kg
25000 mg/kg
125 mg/kg
125 mg/m3
6288 mg/m
LD
100
~ dose fatal to 10° percent of a sample population under stated experimental conditions.
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would certainly not be considered a satisfactory warning of excessive
exposure.
Exposure to carbon tetrachloride in laboratory animals, including
rats, mice, and hamsters, resulted in liver tumors following a variety
of routes of administration including inhalation, ingestion, sub-
cutaneous, and intrarectal. One oral dose study on dogs was negative
and a trout study gave borderline results. There is no evidence of
carcinogenicity to any other organ than the liver, although most
studies were shorter than the life-spans of the animals and tumors
in other organs cannot be ruled out. In humans, no long-term follow-up
study has been reported. Cases of liver tumors in man, following acute
poisoning, have been reported (4). While the results cannot be dis-
missed, their significance is to date unclear. Positive indications
of the mutagenicity of carbon tetrachloride have been reported (5).
The possible teratogenicity of carbon tetrachloride remains in ques-
tion.
There is evidence that potentiation may occur between effects of
carbon tetrachloride exposure and other stresses. Alcohol consumption,
food composition, drug use (especially barbituates), and non-specific
environmental stresses are known to potentiate carbon tetrachloride
damage in mammals (2,6,7). In contrast, diets rich in certain vitamins
or amino acids (notably sulfhydryl-containing compounds) may offer
some degree of protection from liver damage resulting from carbon
tetrachloride exposure (2).
11
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Several biochemical indices (e.g., serum iron levels, glutamate
dehydrogenase activity) have been developed recently that provide in-
dications of past carbon tetrachloride exposure in industrial workers.
Such tests forewarn the appearance of the more conventional clinical
symptoms of hepatotoxicity (2).
The physical properties of carbon tetrachloride (high vapor
pressure and low solubility) should permit some degree of environ-
mental transport, with the majority of movement occurring in the vapor
phase. Biochemical degradation occurs to a limited degree in mammal-
ian systems, with major metabolites being chloroform (CHClo) and carbon
dioxide (CC^). However, no evidence of carbon tetrachloride degrada-
tion by microbial action has been found. Carbon tetrachloride shows
no oxygen consumption in the standard BOD test (8).
Carbon tetrachloride has been found in a variety of environmental
samples at the Mg/kg range or lower (see Table III) . Sediment samples
have not shown any tendency to concentrate carbon tetrachloride to any
appreciable degree above the level found in the surrounding water.
Bioaccumulation in marine life does not appear to be a problem (bio-
concentration factor of 20 in rainbow trout). Observed carbon tetra-
chloride concentrations vary from 1 Mg/kg in fish flesh, to a maximum
of 50 yg/kg in seabird eggs and seal blubber. Analyses of a variety
of foodstuffs indicate the presence of carbon tetrachloride at levels
comparable to those found elsewhere in the environment (see Table IV).
It should be noted that cereal grains which have been recently fumi-
12
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TABLE III
TYPICAL CONCENTRATIONS OF CARBON TETRACHLORIDE IN THE ENVIRONMENT
RANGE (yg/kg wet)
Rainwater 0.01 - 1
Surface water 0.01 - 1
Potable water 0.01 - 1
Seawater 0.1 - 1
Marine sediments 0.1 - 1
Marine invertebrates 1 - 10
Fish 1 - 10
.Waterbirds 1 - 100
Marine mammals 1 - 10
Fatty foods 1 - 10
Non-fatty foods 1
Human organs 1
Human body fat 1 - 10
Source: McConnell, G., D. M. Ferguson, and C. R. Pearson. "Chlorinated
Hydrocarbons and the Environment." Endeavour. January 1975,
p. 13-18.
13
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TABLE IV
OBSERVED CARBON TETRACHLORIDE CONCENTRATIONS IN FOODSTUFFS
RANGE (ug/kg wet)
Dair> produce 0.2 - 14
Meat 7-9
Oils & Fats 0.7-18
Beverages 0.2 - 6
Fruit & vegetables 3-20
Source: McConnell, G. , D. M. Ferguson, and C. R. Pearson. "Chlorinated
Hydrocarbons and the Environment." Endeavour, January 1975,
p. 13-18.
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gated with, carbon tetrachlortde can contain residues as high as 60
mg/kg, while dairy cows under treatment with a carbon tetrachloride
anthelmintic preparation can produce milk containing carbon tetra-
chloride in concentrations of up to 3 mg/kg (9). In both these in-
stances, dietary intake of carbon tetrachloride can be greatly di-
minished if adequate time passes (in storage, handling, and processing)
between treatment and ingestion. Observed levels of carbon tetra-
chloride in human tissues have not indicated any inordinate accumula-
tion. As with other chlorinated hydrocarbons, carbon tetrachloride
tends to be lipid-soluble, but available evidence indicates no bio-
accumulation of carbon tetrachloride in fatty tissues beyond a factor
of about 20 over levels found in kidney, liver, brain, and other
tissues (1)• A. 96-hour LC50* of approximately 50 mg/1 has been
reported in fish (8).
*Lethal Concentration-50. Concentration lethal to 50 percent of
sample population, after 96 hours of exposure.
15
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C. AMBIENT CONCENTRATIONS, POPULATION AT RISK AND MEASUREMENT
TECHNOLOGY
Carbon tetrachlori.de has been monitored extensively in plant
•>
atmospheres, and an industrial standard of 65 mg/nr 8-hour-average
daily exposure has been adopted by the Occupational Safety and Health
Administration. The chemical is not routinely monitored in ambient
air, and only sparse data are available on atmospheric concentrations
in population centers. One study in the Los Angeles Basin reveals a
concentration range of 1 to 2 ug/nr over 54 ground-level sampling stations
in the area, wich an excursion to 10 yg/m near Carson (10). This
latter station was possibly located near a source of the material.
Atmospheric concentrations of carbon tetrachloride downwind of
production facilities may be estimated from hypothetical plant para-
meters, when analytical measurements are lacking. The total atmo-
spheric release of the chemical from the 11 production facilities in
the United States is estimated to be 15 million pounds per year (5).
Hypothetical plant conditions could be used as inputs to a Gaussian
plume equation* from Turner's Workbook of Atmospheric Disperson Esti-
mates (11). The basic diffusion equation should be modified, however,
due to the effect of the plant itself on the flow of air. Mechanical
*Ground-level downwind concentrations resulting from a point source
are predicted by the following equation:
X(x, 0, 0; H) = exp -
16
-.
-) J
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turbulence in the wake of a building tends to produce aerodynamic
down wash., resulting in the fairly rapid diffusion of a gaseous emission
down to the ground. This region of disturbed flow extends downwind a
distance equal to several times the height of the building. While this
situation does not result in a Gaussian-distributed plume, it is pro-
posed that a modification of the usual formula still can be employed.
This is because the turbulent mixing in the wake of the building is
assumed to be distributed uniformly in the vertical direction, analo-
gous to the situation where a plume is trapped below an inversion
layer. A limited vertical mixing height can be modeled using the
equation:
X(x, 0, z; H) = — Q
TTCJyU (..8L)
where: Q = uniform emission rate (grams/sec)
u = mean wind speed affecting the plume (meters/sec)
H = effective stack height; that is, sum of stack height
plus plume rise (meters)
o = horizontal dispersion coefficient evaluated in terms of
downwind distance to the point for which the concentra-
tion is being computed (meters)
o = vertical dispersion coefficient evaluated in terms of
downwind distance to the point for which the concentra-
tion is being computed (meters)
L = the vertical limit of the mixing depth
In the case of an isolated rectangular building, it is assumed that L
equals 1.5 times the building height.
In addition, there is a horizontal wind turbulence which is
assumed to result in an initial horizontal plume spread equal to the
width of the building normal to the wind direction. This is analogous
17
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to an area source emission where the area source is the building top.
This can be modeled using a further modification of the basic Gaussian
diffusion equation. A virtual point source is assumed upwind from the
building at a distance where the plume spread (for the given stability
conditions) would equal the crossvind width of the building. The
modified diffusion equation is therefore:
*<•*• °- " H> " «,; 3 (1.2h)
where H. is the building height and a1 is based on the downwind dis-
y
tance to the receptor point plus the upwind distance to the virtual
point source.
Based on the production losses of Individual carbon tetrachloride
plants and the- assumption that these plants operate 360 days per year
and 24 hours per day (assuming 5 days/year downtime), it has been com-
puted that a typical plant would have a carbon tetrachloride emission
rate of 20 grams per second. Using the modified diffusion equation,
the ambient carbon tetrachloride concentration 500 meters downwind
o
from the release point was calculated to be approximately 1.4 mg/m .*
The downwind distance of 500 meters from the source was chosen to
represent a point within the perimeter of a plant, and ambient con-
centrations in surrounding neighborhoods could be expected to be
^Additional assumptions: (1) carbon tetrachloride is nonreactive;
(2) building height is 50 feet (15.24 meters), and its width equals
100 feet (30.48 meters); (3) stability class is neutral; (4) wind
speed is 6 meters/sec.
18
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significantly lower. The predicted value exceeds background levels
measured in the Los Angeles basin by about one thousandfold.
The global atmospheric concentration of carbon tetrachloride is
reported to be 0.5 to 1.0 yg/nr at 5 to 10 tan altitude (12). The predicted
ground-level concentration 500 meters downwind of a plant may exceed
this background level by a factor of 1500. There exists no ambient
standard for carbon tetrachloride at present, but it is an interesting
observation that a resident 500 meters downwind of a plant would
receive, in a 75-year lifetime, an exposure equivalent to that of an
industrial worker in 7 years of work at the maximum legal occupational
level.
The global atmospheric carbon tetrachloride concentration appears
to be surprisingly constant (12). The hemispheric concentrations are
quite similar-, even through the majority of production and use of
carbon tetrachloride occurs in the Northern Hemisphere. In addition,
carbon tetrachloride does not follow the atmospheric patterns of the
other halogenated hydrocarbons (of anthropogenic origin) which tend
to occur in clearly defined global isopleths surrounding industrial
regions of the world. Finally, the total atmospheric amount of carbon
tetrachloride appears to be in excess of those industrial releases of
the chemical, even if one assumes no loss through degradation. For
these reasons, a natural source of carbon tetrachloride has been sug-
gested, possibly a reaction in the troposphere of methane with chlorine
in a complex sequence of reactions. Preliminary laboratory studies
19
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have shown that the reaction In air of methane (CH^) and chlorine
(Clo) results in the production of small but significant quantities of
carbon tetrachloride (13).
In addition, it is postulated that the chemical may be synthe-
sized by certain forms of vegetation. The entire industrial production
of carbon tetrachloiide during the twentieth century can account for
only two to five percent of the worldwide background concentration (12).
Chemical analysis of carbon tetrachloride at trace levels is well
established. Early techniques depended on pyrolytic decomposition of
the airborne sample, followed by conventional analysis for liberated
chloride. Modern gas chromatographic techniques using an electron
capture detector are capable of quantitative analyses for atmospheric
carbon tetrachloride at the parts-per-trillion level. Colorimetric and
polarographic" procedures have also been reported which are suitable
for the analysis of environmental and physiological samples of the
chemical.
20
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D. SOURCES
Domestic production of carbon tetrachloride was slightly in ex-
cess of one billion pounds in 1974, having shown an average growth
rate of 6.8 percent throughout the previous decade (14). Demand is
estimated to remain at the billion-pound-per-annum level for the 1974-
75 period and future growth is uncertain. The carbon tetrachloride
market is closely tied to sales of aerosol products, since 95 percent
of demand is for the synthesis of fluorocarbon gases and the bulk of
these materials is used for aerosol can propellants. The leveling of
carbon tetrachloride demand reflects a declining trend in aerosol
sales, following a decade of strong growth. Should the use of fluoro-
carbon propellant be banned in the future, carbon tetrachloride demand
could be expected to drop to about 45 percent of its current level.
Carbon tetrachloride production capacity is estimated to exceed
current demand by about 50 percent, although plant facilities are
generally adaptable to the synthesis of other chlorinated solvents.
Certain facilities, known as "swing" plants, are designed to produce
carbon tetrachloride and perchloroethylene in variable ratios. The
operator may elect to vary the product mis by as much as 50 percent.
There are 11 carbon tetrachloride production facilities in the
United States, with a total capacity of 1.5 billion pounds per year,
located as shown in Figure 1. Detailed supporting data are shown in
Table V. Estimates of plant capacity may be misleading, since the
proportion of "swing" plants is unknown. Foreign trade in carbon
21
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FIGURE 1
CARBON TETRACHLORIDE PRODUCTION CAPACITY
100 Million Pounds/year
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TABLE V
CARBON TETRACHLORIDE PRODUCTION DATA
PRODUCER
Allied Chemical
LOCATION
Moundsville, WV
Freeport, TX
Pittsburg, CA
Plaquemine, LA
CAPACITY
Million Lbs./yr.
8
130
45
100
DuPont
Corpus Christi, TX
500
FMC Corporation
S. Charleston, WV
300
Stauffer Chemical
LeMoyne, AL
Louisville, KY
Niagara Falls, NY
200
70
150
Vulcan Chemicals
Geismar, LA
Wichita, KS
35
40
Total Capacity 1,578
Total Production (1973) 1,047
Source: Stanford Research Institute, Directory of Chemical Producers.
Menlo Park, 1975.
23
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tetrachloride appears to be a minor factor In the domestic supply
of the material.
Dispersive uses account for 5 percent of carbon tetrachloride
production, or about 50 million pounds per year. The chemical is used
as a grain fumigant, cleaning agent, rodenticide, anthelmintic, and
specialty solvent. Such applications provide direct entry of carbon
tetrachloride to the atmosphere. Production losses are estimated to
release an additional 15 million pounds per year of the chemical to
the environment. Commercial demand for carbon tetrachloride is outlined
in Figure 2 and summarized in Table VI.
24
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FIGURE 2
CARBON TETRACHLORIDE-COMMERCIAL PATHWAYS
(1973 DATA)
SURPLUS - 4%
58 MILLION LBS/YEAR
1
TOTAL U.S.
PRODUCTION
1047.3
MILLION LBS/YEAR
1
IMPORTS sEXPORTS
i t
TOTAL U.S.
CONSUMPTION
989.3
MILLION LBS/YEAR
T
DISPERSIVE USES - 5%
49.5 MILLION LBS/YEAR
CAPTIVE
USES
95%
PRODUCTION LOSSES 1.5%
16 MILLION LBS/YEAR
DISTRIBUTION LOSSES
(NOT AVAILABLE)
FLUOROCARBONS
939.8
MILLION LBS/YEAR
GRAIN
FUMIGANT
RODENTICIDE
SOLVENT
AEROSOLS - 57%
563.9
MILLION LBS/YEAR
END
USES
REFRIGERANT - 38%
375.9
MILLION LBS/YEAR
Source: National Science Foundation Panel on Manufactured Organic Chemicals, SRI Data, 1975.
-------
TABLE VI
CARBON TETRACHLORIDE COMMERCIAL PATHWAYS
(U.S. Production 1.047 Billion Pounds, 1973)
INDUSTRIAL USES
Freon 11
Freon 12
DISPERSIVE USES
Grain Fumigant
Rodenticide
Anthelmintic
Cleaning Agent -
Solvent
LOSSES
Production Losses
Distribution Losses
Percent
56.1
37.4
4.9
1.5
Amount (Million Lbs.)
587.8
391.8
51.6
15.7
(not available)
Source: National Science Foundation Panel on Manufactured Organic
Chemicals, SRI Data, 1975.
26
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E. CONTROL STRATEGY
Global studies of atmospheric carbon tetrachloride indicate back-
ground levels far in excess of those accountable to industrial sources.
The industrial contribution to the atmosphere can account for only two
to five percent of the worldwide background level, according to studies
of Lovelock and Maggs (13).
The occupational hazard of carbon tetrachloride is well estab-
listed, and industrial atmospheres are rigidly controlled with regard
to solvent vapors. Local populations subjected to industrial losses
or other significant emissions of carbon tetrachloride should be pro-
tected by control equipment at points of plant emissions. Sources
can be controlled with gas scrubbers, adsorption filters, and con-
densors.
Dispersive applications of carbon tetrachloride probably account
for the major occupational and population risks. The use of the
material as an insect and rodent fumigant can be envisioned as an
application which is inherently difficult to control. It is likely
that carbon tetrachloride used in non-industrial applications is
subject to no rigid standards for occupational safety or public
exposure.
27
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REFERENCES
1. McConnell, G., D. M. Ferguson and C. R. Pearson. "Chlorinated
Hydrocarbons and the Environment". Endeavour, January 1975,
p. 13-18.
2. Patty, F. A. Industrial Hygiene and Toxicology, second edition,
pp. 1264-1268. Interscience, New York, 1963.
3. Lai, H., S. K. Puri and G. Fuller. "Enhanced Toxicity of Carbon
Tetrachloride Inhalation after Phenoliarbital Pretreatment."
Pharmacalogy Research 2. C2) , 143-147 (1970) .
4. Tracey, J. P., and Sherlock, P. "Hepatoma Following Carbon Tetra-
chloride Poisoning." N.Y. State J. Med. 68, 2202 (1968).
5. National Science Foundation Panel on Manufactured Organic Chemi-
cals in the Environment, SRI Data, 1975.
6. Yudina, T. V., and Y. V. Novikov. "Changes in the Permeability of
Histohematic Barriers under the action of Chemical Environmental
Factors. Gig. Sanit. 36 (11), 14-18 (1971).
7. Traiger, G. J., and G. L. Plaa. "Relation of Alcohol Metabalism
to the Potentiation of Carbon Tetrachloride Hepatotoxicity
Induced by Aliphatic Alcohols." J. Pharmacol Exp. Ther. 183 (3),
481-488 (1972).
8. Ouellette, R. P., The Mitre Corp., Personal Communication.
9. International Agency for Research on Cancer. IARC Monographs on
the Evaluation of Carcinogenic Risk. !_, 53-60, 1972.
10. Simmonds, P. G., P. S. Kerrin, J. E. Lovelock, and F. H. Shair.
"Distribution of Atmospheric Halocarbons in the Air Over the
Los Angeles Basin." Atm. Envir. £, 209-216 (1974).
11. Turner, D. B. Workbook of Atmospheric Dispersion Estimates.
U.S. Department of Health, Education and Welfare, Revised 1969.
12. Lovelock, J. E. "Atmospheric Hydrocarbons and Stratospheric
Ozone." Nature 252. 291-293 (1974).
13. Lovelock, J. E., R. J. Maggs, and R. J. Wade. "Halogenated
Hydrocarbons In and Over the Atlantic." Nature 241, 194-196
(1973).
14. Stanford Research Institute, Chemical Economics Handbook. Menlo
Park, 1973.
29
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Additional Resources
American Conference of Governmental Industrial Hygenists. Documentation
of the Threshold Limit Values for Substances in Workroom Air, Third
Edition. Cincinnati, 1971.
American Society for Testing and Materials. Instrumentation for Moni-
toring Air Quality. Special Technical Publication 555, Philadelphia,
1974.
Bond, Richard G., and Conrad P. Straub, Handbook of Environmental
Control. Chemical Rubber Company, Cleveland, 1972.
Chemical Marketing Reporter. 202 (7), 9 (1975).
Danielson, J. A. Air Pollution Engineering Manual. Environmental
Protection Agency, Research Triangle Park, N.C., 1973.
Kirk, R. E., Encyclopedia of Chemical Technology, Second Edition. New
York, Wiley, 1968.
Liss, P. S., and P. G. Slater. "Flux of Gases Across the Air-Sea Inter-
face." Nature 247:181-184 (1974).
Stanford Research Institute, Directory of Chemical Producers, Menlo
Park, 1975..
Sunshine, Irving. Handbook of Analytical Toxicology. Chemical Rubber
Company, Cleveland, 1969.
Tariff Schedules of the United States Annotated. United States Inter-
national Trade Commission, Washington, 1975.
United States Department of Health, Education and Welfare. Survey of
Compounds Which Have Been Tested for Carcinogenic Activity. Public
Health Service Publication #149, 1971.
United States Department of Health, Education and Welfare. The Toxic
Substances List. Public Health Service, National Institute for
Occupational Safety and Health. Rockville, Maryland, 1973.
United States House of Representatives, Committee on Interstate and
Foreign Commerce, Fluorocarbons - Impact on Health and Environment.
HR 17577 and HR 17547. Government Printing Office, Washington, 1975.
United States Production and Sales of Miscellaneous Chemicals, 1973
Preliminary. United States International Trade Commission, Washing-
ton, 1975.
30
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Additional Resources (Concluded)
Wilkness, P. E., R. A. Lamontagne, R. E. Larson, J. W. Swinnerton,
C. R. Dickson and T. Thompson. "Atmospheric Trace Gases in the
Southern Hemisphere." Nat. Phys. Sci. 245:45-47.
Von Oettingen, W.F. The Halogenated Hydrocarbons of Industrial and
Toxicological Importance, pp. 107-174. Elsevier, Amsterdam, 1964.
31
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing}
1 REPORT NO
MTR-7144
3 RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Air Pollution Assessment of Carbon Tetrachloride
5 REPORT DATE
February 1976
6. PERFORMING ORGANIZATION CODE
7 AUTHOR(S)
Richard Johns
8. PERFORMING ORGANIZATION REPORT NO.
9 PERFORMING ORGANIZATION NAME AND ADDRESS
10 PROGRAM ELEMENT NO.
The Mitre Corporation
McLean, Virginia 22101
11. CONTRACT/GRANT NO.
68-02-1495
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U. S. Environmental Protection Agency
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA-AWM
15 SUPPLEMENTARY NOTES
16. ABSTRACT
This report concerns the organochlorine solvent carbon tetrochloride,
which is used primarily in the manufacture of fluorocarbons. The toxic
effects of the solvent in both animals and man are discussed and the prob-
ability of those effects occurring at the ambient atmospheric concentrations
to which the general population is exposed is assessed. Methods for
atmospheric sampling of carbon tetrachloride and available control technology
for the prevention of release to the environment are also discussed.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Croup
Organic Compounds
Organic Solvents
Physiological Effects
Fluorohydrocarbons
Air Pollution Control
Stationary Sources
Hydrocarbons
Carcinogens
Air Pollution
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Unlimited
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36
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