GCA-TR-75-32-G (4)
ASSESSMENT OF BENZENE
AS A POTENTIAL AIR POLLUTION PROBLEM
VOLUME IV
FINAL REPORT
Contract No. 68-02-1337
Task Order No. 8
Prepared For
U.S. ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park
North Carolina 27711
January 1976
GCA TECHNOLOGY DIVISION ®©A
BEDFORD, MASSACHUSETTS 01730
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GCA-TR-75-32-G(4)
ASSESSMENT OF BENZENE
AS A POTENTIAL AIR POLLUTION PROBLEM
Volume IV
by
Robert M. Patterson
Mark I. Bornstein
Eric Garshick
GCA CORPORATION
GCA/TECHNOLOGY DIVISION
Bedford, Massachusetts
January 1976
Contract No. 68-02-1337
Task Order No. 8
EPA Project Officer
Michael Jones
EPA Task Officer
Justice Manning
U.S. ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park
North Carolina 27711
-------
This report was furnished to the U.S. Environmental Protection Agency by the
GCA Corporation, GCA/Technology Division, Bedford, Massachusetts 01730 in
fulfillment of Contract No. 68-02-1337, Task Order No. 8. The opinions
findings, and conclusions expressed are those of the authors and not neces-
sarily those of the U.S. Environmental Protection Agency or of the cooperating
agencies. Mention of company or product names is not to be considered as an
endorsement by the U.S. Environmental Protection Agency.
-------
ABSTRACT
This report is one of a series which assesses the potential air pollution
impacts of 14 industrial chemicals outside the work environment. Topics
covered in each assessment include physical and chemical properties,
health and welfare effects, ambient concentrations and measurement meth-
ods, emission sources, and emission controls. "The chemicals investigated
in this report series are:
Xrolume I
Volume II
Volume III
Volume IV
Volume V
Volume VI
Volume VII
Volume VIII
Volume IX
Volume X
Volume XI
Volume XII
Volume XIII
Volume XIV
Acetylene
Methyl Alcohol
Ethylene Bichloride
Benzene
Acetone
Acrylonitrile
Cyclohexanone
Formaldehyde
Methyl Methacrylate
Ortho-Xylene
Maleic Anhydride
Dimethyl Terephthalate
Adipic Acid
Phthalic Anhydride.
iii
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CONTENTS
Page
Abstract ill
List of Figures v
List of Tables v
Sections
I Summary and Conclusions 1
II Air Pollution Assessment Report 3
Physical and Chemical Properties 3
Health and Welfare Effects 4
Ambient Concentrations and Measurement 11
Sources of Benzene Emissions 15
Benzene Emission Control Methods 21
III References 26
Appendix
A Benzene Production Capacity 29
iv
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FIGURES
No. Page
1 Benzene Flow Chart 16
2 Estimated Installed Cost of Benzene Storage Tanks
(Equipment Costs Assumed to be the Same as Gasoline
Storage Tanks) 25
TABLES
No. Page
1 Significant Properties of Benzene 3
2 Individual Cases 7
3 Group Statistics 7
4 Benzene Consumption for Final Products - 1974 15
5 Benzene Emissions 18
6 Estimated Installed Costs of Adsorption Systems 22
7 Estimated Annual Operating Costs of Adsorption Systems 22
8 Estimated Installed Costs of Thermal and Catalytic
Incinerators 24
9 Estimated Annual Operating Costs of Thermal and
Catalytic Incinerators 24
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SECTION I
SUMMARY AND CONCLUSIONS
Benzene poisoning usually occurs through inhalation of the vapor, al-
though penetration through the skin can be a contributing factor. The
concentration and duration of exposure determines the severity of ben-
*
zene poisoning. A concentration of 20,000 ppm is a lethal dose for man
if the duration of exposure reaches 5 to 10 minutes. Acute poisoning
has a narcotic effect on the central nervous system. The current OSHA
standard for workers is a time weighted average of 10 ppm for an 8-hour
work day and a 40-hour work week. Continual exposure to higher concen-
trations may cause chronic poisoning which acts through a toxic effect
on the blood-forming tissues. At concentrations in the range of 5,000
to 14,000 ppm, benzene has been shown to produce acute toxic effects on
plants. Benzene is only minimally reactive in photochemical smog.
Emissions of benzene occur primarily from motor vehicles, benzene pro-
duction, end product manufacture, solvent usage, and storage and handling
losses. Total emissions of benzene are estimated to be 1,149 million
pounds per year. Vehicle emissions account for 79 percent, while benzene
production, end product manufacture, solvent usage, and bulk storage
account for the remainder. Estimated 1974 production of benzene was
11.6 billion pounds, and production is expected to increase at an annual
rate of 7 percent for the next several years. Benzene production is
concentrated in the Gulf states with 37 percent produced in Texas. How-
ever, the two largest plants producing 17 percent of the total U.S. pro-
duction are in Puerto Rico. Benzene is used primarily as an intermediate
in the production of ethylbenzene, phenol and cyclohexane.
-------
Benzene emissions can be controlled by adsorption with vapor recovery
or incineration. Emissions from storage tanks can be controlled through
the use of floating roof tanks or fixed roof tanks vented to an adsorp-
tion or incineration unit. Although control equipment specifically for
benzene emissions has not been reported in the literature, devices for
the control of other similar chemicals have been reported recently. Two
types of control devices are presently used in the manufacture of styrene;
these are vapor recovery by adsorption and incineration. Both systems
have the capability of controlling benzene, toluene and styrene emissions
to almost 100 percent. Since these systems are currently being used by
the styrene industry, and since benzene is closely related, it is assumed
that the two control systems can also be used in the production of benzene.
Simple diffusion model calculations place the expected maximum 1-hour
and 24-hour ambient concentrations in a nonwork environment at about
4 ppm and 2 ppm, respectively. These estimates apply to the largest
capacity benzene production facility.
Based on the health research studies and the ambient concentration con-
siderations presented in this report, it appears that benzene in air
does not pose an imminent threat to the health of the general population,
nor does it pose other adverse environmental insults as an air pollutant.
However, due to the toxicity of benzene, it is concluded that a small-
scale monitoring study may be appropriate.
-------
SECTION II
AIR POLLUTION ASSESSMENT REPORT
PHYSICAL AND CHEMICAL PROPERTIES
Benzene is a clear, colorless, highly flammable liquid with a distinctive
*
aromatic odor. Benzene can be manufactured from coal, or can be obtained
from petroleum by the catalytic reforming of naphthenes or by the hydro-
dealkylation of toluene. It is used as a solvent and a chemical inter-
mediate in industry, and is found in gasoline. Selected physical and
chemical properties are presented in Table 1.
Table 1. SIGNIFICANT PROPERTIES OF BENZENE
Synonyms
Benzol, phenyl hydride, coal naphtha,
phene, benzole, cyclohexatriene
Chemical formula
Molecular weight
Boiling point
Melting point
Specific gravity
Vapor density
Vapor pressure
Solubility
Explosive limits
Autoignition temperature
Flash point
At 25°C and 760 mm Hg
C6 H6
78.11
80.1°C
5.5°C
0.879 (20°/4°C)
2.7 (air = 1)
79 mm Hg at 20°C
Very soluble in most organic solvents;
not soluble in water
1.4% to 6.8% by volume
538°C
-11°C (closed cup)
1 ppm =3.2 mg/nr
1 rag/m^ = 3.1 ppm
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HEALTH AND WELFARE EFFECTS
Effects on Man
Acute Poisoning - The effect of benzene poisoning varies with the concen-
tration in air and the duration of exposure. Flury and Zernik give the
following as a guide to lethal and toxic concentrations of benzene in air
for a single dose to man:
Concentration Exposure Response
20,000 ppm 5-10 minutes Fatal
7,500 ppm 30-60 minutes Acute poisoning symptoms
j
3,000 ppm 30-60 minutes Tolerance limit.
A concentration of 100 ppm produces only minor mucous membrane irrita-
2
tion. Concise data are lacking in the literature on the concentration
in air at which benzene begins to exert an acute effect on man. One
reason for the lack of data is that individual susceptibility varies
considerably. Rescuers of unconscious workmen, usually overcome in an
345
enclosed area such as a tank containing benzene residue, ' ' have died
while the original victim recovered upon removal from the benzene fumes.
Most industrial poisoning results from inhalation of benzene vapors.
Oral ingestion causes local irritation of the mouth, throat, esophagus,
and stomach, followed by blood absorption and the systemic symptoms of
acute benzene poisoning. Absorption of both liquid and gaseous benzene
through intact skin is poor, and is insignificant in contributing to the
6
incidence of benzene poisoning.
The data of Flury and Zernik indicate that at concentrations approaching
3,000 ppm benzene has a narcotic effect on man resembling the effect of
other low molecular weight compounds such as chloroform. The initial
exhilaration upon inhalation, greater than with chloroform, produces
drowsiness, fatigue, nausea, and headache. Breathlessness, irritability,
-------
and unsteadiness in walking may persist for 2 to 3 weeks following expo-
sure. Higher concentrations of benzene irritate the mucous membrane of
the eyes, nose, and respiratory tract. An initially high respiratory
rate decreases as exposure to the vapor continues, ultimately resulting
2
in death by circulatory or respiratory collapse. Autopsy reports after
acute benzene death show hemorrhage in the brain, pleurae, pericardium,
urinary tract, mucous membrane, and skin. As little as 0.094 rag percent
3
to 2.0 mg percent benzene by weight has been found in the blood at the
time of death.
Inhaled benzene is absorbed by the body at a high rate. Humans breathing
air containing 3,000 to 5,000 ppm benzene absorb approximately 80 percent
9
of the total benzene inhaled. Seventy to eighty percent benzene satura-
2
tion of the blood occurs within 30 minutes. Benzene has a great affinity
toward specific body tissues. For example, 40 to 60 percent of the ben-
zene in the blood can become fixed in the bone marrow, fatty tissue, and
liver. The fat and bone marrow especially act as reservoirs, losing
absorbed benzene slowly, maintaining the poisoning effect of benzene on
the body's system. Only 0.2 percent of the benzene dose is eliminated
from the body as urinary benzene. Blood, fatty tissues, and bone marrow
benzene is metabolized to phenol and phenol derivatives and excreted in
the urine. The phenols produced by benzene oxidation are also responsible
for many of the ill effects of benzene poisoning. Most phenols excreted
in the urine are present as detoxified conjugation products of phenol and
glycine, glucuronic acid, or sulfate. When the process of conjugation is
delayed, such as when there is a shortage of inorganic sulfate in the
body, the phenols are left free to exert their toxic action.
Chronic Poisoning - Chronic exposure to benzene vapor over a period of
years has an injurious effect on the blood forming system of the body.
Numerous case studies have been reported linking a high incidence of
leukemia and preleukemic symptoms in workers to benzene vapor exposure.
-------
The symptoms have been attributed to the accumulation of benzene in the
bone marrow, which is responsible for the production of red and white
blood cells. A symptom of early poisoning is an increased lymphocyte
count, with a total decreased white blood cell count. Later symptoms
include a sharper decrease in white blood cell count, the appearance of
immature and abnormal white corpuscles, and a markedly reduced white
blood cell count. Up to this point, benzene poisoning can occur without
any clinical signs or symptoms. ' Blood tests are required to identify
the poisoning. In advanced stages of poisoning, the individual will show
signs of aplastic anemia: pallor, weakness, fatigue, shortness of breath,
palpitation, and a progressive reduction of all blood cell types and
hemoglobin. There may be bleeding of the gums and hemorrhaging under the
skin due to increased capillary fragility. Different forms of leukemia
can develop with or without the onset of aplastic anemia. Leukemia is
generally characterized by the uncontrollable proliferation of immature
white blood cells into the blood. The most common type of leukemia asso-
ciated with benzene poisoning Is acute leuke.,.:'a characterized also by
anemia, an enlarged spleen, ami body hemorrhages. Bone marrow appearance
can vary from that of defective development to a complete absence of
development.
Table 2 summarizes studies done on individual workers relating benzene
concentration to the time of exposure and the onset of disease. Table 3
summarizes the results of two studies on the effect of benzene exposure
on the blood pictures of groups of workers.
Chromosome studies were performed on blood lymphocytes of workers exposed
to benzene concentrations varying from 125 to 532 ppm. Significant num-
12
bers of chromosome changes were observed. Similar studies were per-
formed on persons whose bone marrow contained benzene residue, both those
who had recovered from the symptoms of chronic benzene exposure, and
those who had recovered from acute benzene poisoning. In both cases,
-------
there was a persistence in stable chromosome changes — changes still
present several years after benzene exposure. In another example,
chromosome changes were found in the bone marrow cells before the onset
of leukemia. Stable chromosome chi
clones that would become leukemic.'
of leukemia. Stable chromosome changes could give rise to abnormal
14
Table 2. INDIVIDUAL CASES
6,11
Study
1
2
3
Age
47
38
28
Sex
M
M
M
Source
Shoe
adhesive
Roto-
gravure
Shoe
adhesive
Duration
14 years
4 years
8 years
Concentration
210 ppm
190-660 ppm
150-210 ppm
Description
Aplastic anemia for
2 months from
acute myeloblas-
tic leukemia
Death due to my-
eloid metaplasia
of 1 iver and
spleen
Death from acute
myeloblastic
leukemia
Table 3. GROUP STATISTICS
Study
1
2
Industry
Rubber
coating
Leatherette
factory
Number of
workers
52
121
60
71
Concentration
60-80 ppm
78 ppm
31-62 ppm
24-39 ppm
Comment
8-year study: 16 workers
had an abnormal blood
picture
5-year study : 80 percent
had abnormal white cell
function
5-year study: 60 percent
had abnormal white cell
function
5-year study: some altera-
tion of blood elements
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It can be seen from Tables 2 and 3 that chronic exposure to as little as
30 ppm benzene can upset the normal blood picture. The current OSHA
standards for exposure to benzene specify that a worker's exposure to
benzene must not exceed a time-weighted average of 10 ppm in any 8-hour
work shift of a 40-hour work week. The worker may be exposed to a con-
centration of benzene above 25 ppm but below a peak of 50 ppm for a maxi-
mum period of 10 minutes during an 8-hour shift.
Effects on Animals
Acute Poisoning - Rabbits have been exposed to 35,000 to 45,000 ppm ben-
£
zene vapor in air with the following results :••
Average exposure time Response
3.7 minutes Light anesthesia
5.0 minutes Excitation
36.0 minutes Death.
Dogs exposed to benzene vapor developed hypertension, followed by paraly-
sis of the vasomotor system due to benzene acting on the smooth muscle of
2
the blood vessels. Rats subjected to a single exposure of 18,750 ppm
showed changes in the activity of enzymes in the central nervous system.
However, the reaction to benzene was not the same in all neurons; vary-
ing degrees of enzymatic response were found. It was postulated that the
changes in activity were due to the direct lesion of the lipoprotein mem-
branes of the cell's structural elements by benzene or a benzene
metabolite.
Chronic Poisoning .- Rats exposed to 1,000 ppm benzene for 23% hours per
day, 7 days per week, hemorrhaged from the nose and mouth after 183 hours;
the stomach was distended and the gut was empty with a loss of body weight.
The blood vessels of the lungs, liver, kidneys, intestines, and abdominal
tissues were engorged. In addition, there was a low white blood cell
count, an increase in the number of polymorphs relative to lymphocytes,
-------
and a lower leukocyte DNA value. Rats exposed to 1,000 ppm benzene for
only 18 hours per day had similar symptoms after 1,782 hours. Rats of
this latter group showed no exposure symptoms after recovering for
6% months except for the low leukocyte DNA value. Rats exposed for
8 hours per day, 5 days per week, to 200 ppm benzene had a fall in
their white blood cell count after 750 hours. At 50 ppm with exposure
for 8 hours per day, 5 days per week, up to 750 hours, there was a fall
in the white blood cell count with 50 percent of the rats developing
bilateral cataracts. Microscopic studies of the bone marrow in all cases
showed an increase in the number of red blood cell precursors together
with lower leukocyte DNA values.
Benzene also acts as a central nervous system depressant. A delay was
found in the conditioned reflex response time of rats exposed to benzene
vapor at 20 ppm for 6 days per week, for 5^ months. No reflex delay was
found at 4 ppm. It can be theorized that benzene-triggered functional
disturbances of the central nervous system manifest themselves prior to
the occurrence of changes in blood morphology.
As in man, a typical symptom of benzene poisoning is anemia. An initial
rise in blood platelets is followed by a rapid fall and anemia. There
is a final fall in total leukocytes preceded by an initial rise. Ben-
zene has been found to lower the resistance of animals to infection by
reducing the number of antibodies formed, reducing the number of leuko-
cytes, and reducing the phagocytic activity of the leukocytes. Mice
treated subcutaneously with a drastic dose of benzene (1,232 mg per kg
body weight) administered over a period of 52 weeks were found to con-
15
tract cancer.
Effects on Vegetation
Tomato, barley, and carrot plants were exposed to 7,200 ppra benzene
vapor in a gas chamber. Benzene had an acute toxic effect on the
-------
plants, entering the plant tissue rapidly. A darkening of the tips of
the younger leaves indicated sap leaking into intercellular spaces and
tissue breakdown. As the darkening spread, there was a loss of rigidity
and a marked drooping of leaves and stems. When exposed to bright light,
the chlorophyll in the plants was destroyed, resulting in the complete
bleaching of affected plant portions. Barley exposed to 7,200 ppm ben-
zene vapor for 1 hour were dead within 24 hours. Tomato plants exposed
for 2 hours were dead within 24 hours, while the carrots, although
severely damaged, were not killed by a 2-hour exposure. Benzene was
shown to be toxic only over a narrow range of concentrations. Barley
exposed to 4,900 ppm benzene vapor for 4 hours were only slightly dam-
aged 1 week after the treatment, with complete recovery 4 weeks after
exposure. When exposed to 14,000 ppm benzene for 30 minutes, all the
plants were dead within 24 hours.
Benzene is a contact poison in plants. Entry to the leaf is through the
cuticle and stomata. When the benzene is present in sufficient concen-
tration, the tissue dissolves due to the disruption of the lipoid ele-
ments of the cell membrane. The effect of benzene on plants is acute.
Chronic toxicity has not been demonstrated, as evidenced by the recovery
of some of the test plants exposed at lower concentrations.
Other Effects - Benzene and Photochemical Smog
It is well documented that the reactions taking place in photochemical
smog produce ozone and peroxyacetyl nitrate (PAN), two chemical species
extremely toxic to plants (and man). ' Benzene is only minimally
reactive in photochemical smog as compared to other aromatics such as
toluene, and other hydrocarbons including most aliphatics, ketones, and
20 21
aldehydes. ' Photochemical reaction products involving benzene have
22
proven capable of damaging vegetation in the laboratory, but under
ambient conditions and concentrations would not be significant in con-
tributing to such damage as compared to the reaction products from the
more reactive hydrocarbons.
10
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AMBIENT CONCENTRATIONS AND MEASUREMENT
Measurements of benzene in urban atmospheres have shown concentrations
O *3 O / 1 O
to be of the order of 0.01 ppm. ' A study in Los Angeles revealed
average concentrations of about 0.015 ppm, with a maximum value of
24
0.057 ppm. Concentrations m.Msured in Toronto averaged 0.013 ppm,
with a maximum of 0.098 ppm.
25
A study was conducted at t -pical casoline retail service stations and
bulk loading installations Jn Britain during the summer of 1969, mostly
during warm weather and whil< there was a relatively high demand for
gasoline. A series of 30-minute personal samples were taken at a sam-
pling rate of 1 liter per minute during the entire work period of ser-
vice station operators, and Muring the entire period of loading or dis-
charging of gasoline for bulk installation operators or tank truck
(road car) drivers. Nine service stations were surveyed, four of which
were large ?nd >pen with a high annual salej volume of gasoline, and
four which were "typical filling station^" of medium size and somewhat
enclosed with average annual sales. One station represented a site in
dense urban areas, being verv enclosed and with a relatively high annual
sales volunr1 of gasoline. Benzene content of gasolines ranged from
2.8 to 5.8 percent by volume in weather situations ranging from sunny
to changeable, with variable ^mperature and wind conditions. Ambient
benzene concentrations ranged from 0.2 to 3.2 ppm from a total of 121
tests taken. Normal handling, procedures at bulk loading facilities with
gasolines ranging from 0.4 i •> 6.8 percent benzene by volume resulted in
ambient benzene concentrations ranging from 0.1 to 7.7 ppm for 70 total
determinations.
Ambient Concentration Estimaic.fi
The largest Installation for the production of benzene has a capacity
of 160 million gallons per year. Assuming a loss of 0.5 percent, this
converts to an emission rate of
11
-------
(0.005 emission factor)(160 : j_0^_ gal/yr)(3.785 x 1Q3 cc/gal)(0.879 gm/cc)
•!. .1 Vii'i :c JO7 seo./yr
= 84.4 gm/sec of benzene.
Some assumptions must be mad< regarding the- characteristics of this ben-
zene release to the atmosphere. In the first place, it is assumed that
the concentrations of benzene a/*.: likely to be highest around production
facilities. Secondly, the ben/ene emissions do not all come from one
source, but rather from the numerous vents, condensers, valves, and reac-
tors at the facility. Thus, the emi ssior.s can be characterized as coming
from an area source which will be taken to be l-fj(i meters on a side. Fi-
nally, the emissions do not occur at rround level, but at different
heights, and an average etui ssion 11014 ht of 10 iiiei ei s is '-'nosen as a
characteristic value.
Ground level concentrations can then be estin^:~ ^u at locations downwind
26
of the facility.^ To do rhi.s, .1 virtu.-Ti ^rinu .sosrcc of emission is
assumed upwind of the facility -•:: a distance viiti'^ tr.e initial horizontal
dispersion coet'f icit'.nt equals Lie length of a side of the area divicl. !
by 4.3. In this case:
= lOii m/4.3 - 23. 3 n.
'Cl
Assuming neutral sL-shilir c >nai tioas (l'a:-quil 1-Cif ford Stability Class D)
with overcase skies and light winds, the upwind distance of the virtual
point source is approx nun ( elv 310 meters. With '-.ons i deration of uhe plant
boundary, it is reasonable Lo assume that the nearest receptor location is
t'hus .about 500 meters i_V"i» the i/i.rtual point somva. Finally, t@kipj5
2 m/s&e s§ an average wind speed, the pi"«ufld levei eon§eftferafei@a§ aay be
12
-------
v- Q e
uira a
84.4 -l/2f 10
or x ~ (2) TT (36) (18.5)
= 1.743 x 10~2 gm/m3
for a 10-minute average concentration. Over a period of an hour this
becomes (1.743 x 10~2 gm/m3) 0.72 = 1.063 x 10~2 gm/m3 or 3.9 ppm 1-hour
average concentration. Over a 24-hour period, the average concentration
might roughly be expected to about 2 ppm.
For similar conditions, the 1-hour and 24-hour average concentrations at
the facility with the next greatest capacity (110 million gallons/year)
would be in direct proportion to the ratio of the two capacities:
110/160 million gallons/year, or 0.69. Hence, the two time period con-
centrations would be 2.7 ppm and 1.4 ppm.
Measurement Techniques
Analytical methods for measuring benzene concentrations in air include
ultraviolet absorption spectrophotometry, colorimetry, and gas chroma-
tography. Air is either drawn through a bubbler or passed over silica
gel or charcoal to remove the benzene sample from the air. Sensitivity,
specificity, and accuracy are functions of the sampling method used and
of the sampling interval. Features of the techniques are discussed below.
77 78
Ultraviolet Absorption Spectrophotometry ' - Benzene absorbs ultra-
violet light at a wavelength of 254.5 nanometers. Concentrations may be
determined by comparing the absorbence of the sample with the absorbence
13
-------
of known standards. In this technique, air is drawn through a tube
containing silica gel. After collection, the silica gel is immersed
in isooctane with water present. The water displaces the benzene,
which in turn is dissolved in the isooctane. This method is not spe-
cific for benzene, as other aromatic hydrocarbons will interfere. The
method is not sensitive enough for air pollution work, the lower detec-
tion limit being about 10 ppm of benzene.
27 29
Colorimetric Methods ' - In this technique, air is drawn through a
fritted bubbler containing either naphtha or alcohol, or a solution of
sulfuric acid and fuming nitric acid. After preparation, the concen-
tration in the sample is determined spectrophotometrically. The method
using sulfuric and fuming nitric acid is not sensitive enough for air
pollution measurements, and interferences arise from toluene, ethyl-
benzene, chlorobenzene, styrene, and xylene. Collection in petroleum
naphtha or alcohol, however, is specific for benzene, and concentra-
tions as low as about 1 ppm can be detected. A crimson color is pro-
duced which is read at a wavelength of 620 nanometers.
30
Gas Chromatography - This technique is capable of detecting benzene
at concentrations well below 1 ppra. Air is drawn through a tube con-
taining charcoal on which organic vapors are adsorbed. The sample is
then desorbed using carbon disulfide, and an aliquot of the desorbed
sample is analyzed using a gas chromatograph. The presence and con-
centration of benzene are determined from its characteristic retention
time and the area of the breakthrough curve.
This technique is especially well-suited for air pollution work since
there is no requirement for chemicals in the field.
14
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SOURCES OF BENZENE EMISSIONS
Benzene Production and Consumption
The production of benzene is estimated to have been 11.6 billion pounds
in 1974, and it is expected to increase at 7 percent per year for the
31
next several years. Almost 45 percent of all benzene consumed domes-
tically is used in the manufacture of ethylbenzene, which is used to
make styrene. An additional 19 percent is consumed in the manufacture
of phenol, an intermediate for the synthesis of polymeric materials,
and 16 percent is used in the manufacture of cyclohexane. The bulk of
the remainder is used in the manufacture of solvents and other nonfuel
uses. A flow chart with the routes of the various benzene derivatives
is shown in Figure 1, while the consumption of benzene for final prod-
ucts and the expected growth rate for each product are shown in Table 4.
32
Table 4. BENZENE CONSUMPTION FOR FINAL PRODUCTS - 1974
32
Product
Ethylbenzene
Phenol
Cyclohexane
Maleic anhydride
Detergent alkylate
Aniline
Dichlorobenzenes
DDT
Other nonfuel uses
Total
Million pounds
5,140
2,230
1,818
451
449
412
130
62
938
11,630
% Annual growth
7
7
5
13
0
12.5
0
- 1.5
5
7
Benzene is produced by 40 companies at 61 plants. Petroleum refiners
and petrochemical manufacturers are the primary producers. Production
15
-------
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PHENOLIC RESINS
ALKYLPMENOLS, €.9. NONYLPMEN
AOIP1C AGIO
SOLVENT REFINING 1
PENTACHLOROPHGNOL
PHCNOLPHTHALEIN
PESTIC'OES. «g.. M6THOXYCHLOR
SOLVENT
METHYL ISO8UTYL KETONE~
METHYL ISOBUTY*LCARBINOL
MESITYL OXIDE
ISOPHOHONE
DIACETONE ALCOHOL
HEXYLENE GLYCOL
BISPHENOL-A
METHYL METHACRYLATE
DRUGS
OYES
RUBBER CHEMICALS
RUBBER ACCELERATOR
RUBBER ANTIOXIDANT
POLYURETHANES
RUBBER ANTIOX;OANT
°L'^^YES
EXPLOSIVES
HERBICIDE
RUBBER PROCESSING CHEMICAL
MEDICINALS
ADIPIC ACID
CYCLOHEXANONE -^__^^
PHENOLIC RESINS
HERBICIDES
POLYPHENYLENE OXIDE RESINS.
— PLASTICIZERS
— SOLVENTS
_TPLASTICS
[SURFACE COATINGS
PHOTOGRAPHIC DEVELOPER
ANTIOXIDANT
OYES
MEDICINALS
LUBE OIL ADDITIVES
SURFACE-ACTIVE AGENTS
EPOXY RESINS
POLYCARBONATE RESINS
PHENOLIC RESINS
RUBBER ANTIOXIDANT
WOOD PRESERVATIVE
HERBICIDE
CAPROLACTAM
NYLON 6
^ PLASTICS
• >
-------
is concentrated in the Gulf states and Puerto Rico. The 10 largest
plants account for 51 percent of total production capacity. A list of
33
companies, plant locations, and capacity is presented in Appendix A.
Benzene Sources and Emission Estimates
The major source of benzene emissions results from motor vehicle evapor-
ative losses and exhaust emissions. Other sources of losses are from
production, end product manufacturing, solvent usage, and bulk storage
and handling. Total emissions of benzene (see Table 5) are estimated
to be 1,148.9 million pounds.
Table 5. BENZENE EMISSIONS
Source
Vehicle exhaust
Vehicle evaporative loss
Benzene production
End product manufacturing
Solvent usage
Gasoline handling
Bulk storage
Total
Million pounds
840.8
68.5
58.1
57.9
54.6
35.0
34.0
1,148.9
Two important sources of benzene emissions, not associated with its
production or its final use, are motor vehicle exhaust and motor ve-
hicle evaporative losses. Total hydrocarbon emissions from transpor-
tation sources are estimated to have been 24,914 million pounds in 1974.
This figure is calculated by extrapolating the national NEDS motor ve-
hicle emissions from 1972 to 1974, based upon a recent transportation
34
survey for Rhode Island. This survey indicated that hydrocarbon
emissions have decreased approximately 15 percent since 1972.
18
-------
Approximately 75 percent of all vehicle hydrocarbon emissions result
35
from the exhaust system. Analyses of vehicle exhaust gases have
O f.
indicated that approximately 4.5 percent by weight is benzene. Using
these two factors will result in 840.8 million pounds of benzene emitted
from motor vehicle exhaust.
The remaining 25 percent of the hydrocarbon losses are a result of
evaporative emissions. The concentration of benzene in gasoline varies
with the type of fuel burned. A gas chromatograph analysis has indicated
that regular gasoline contains approximately 1.35 percent and that pre-
mium gasoline contains approximately 0.81 percent benzene by weight.
Using an average value of 1.1 percent will result in 68.5 million pounds
lost to the atmosphere.
Another major source of emissions is the manufacture of benzene. Benzene
is usually identified according to its source as either being coal-derived
or petroleum-derived. It is currently manufactured almost exclusively
(88 percent of total production) by petroleum refiners and petrochemical
producers. Nine companies with 16 locations manufacture coal-derived
benzene, while 31 companies with 45 locations manufacture petroleum-
derived benzene.
About 70 percent of the petroleum-derived benzene is obtained from
catalytic reformate, a process used primarily to manufacture high octane
gasoline containing a high proportion of aromatics. Another 9 percent
is a by-product of hydrodealkylating-toluene, while 11 percent is re-
claimed from pyrolysis gasoline, which is a by-product of olefin manu-
facture. The remaining amounts are obtained when higher alkyl aromatics
are dealkylated to naphthalene and from the dealkylation of toluene.
Very little data exist in the literature concerning benzene emissions.
Based upon data available in AP-42 and emission data for other similar
19
-------
processes, it is estimated that 0.5 percent of total benzene production
is lost from manufacturing operations. The major sources of emissions
are vents, condensers, valves, and reactors. Using the emission factor
of 0.5 percent and the 1974 production rate of 11.63 billion pounds,
emissions resulting from benzene production are 58.1 million pounds
per year.
Similarly, it is estimated that emissions from the use of benzene to
manufacture other products is also 0.5 percent. Since 11.58 billion
pounds of benzene (excluding solvent usage) are used to manufacture
other products, emissions from this category are 57.9 million pounds
per year.
Another source of benzene emissions is its use as a solvent for paints,
adhesives, and thinners. It is assumed that all benzene used as a sol-
vent will be emitted to the atmosphere. Emissions in 1974 are, there-
fore, estimated to have been 54.6 million pounds.
Emissions will also occur from bulk storage and handling. Using
the emission factors presented in AP-42, the yearly consumption of
37
benzene, and assuming that all storage tanks are fixed roof, storage
emissions are 34 million pounds per year.
The final major emission source is the distribution and handling of
gasoline. In 1974, 98.1 billion gallons of gasoline were sold in
the United States. Losses result from service stations and from tank
truck loading and unloading. Using the AP-42 emission factors and
assuming benzene is 1 percent of the vapor, 35 million pounds of
benzene is 1 percent of the vapor, 35 million pounds of benzene were
lost to the atmosphere from the handling of gasoline.
20
-------
BENZENE EMISSION CONTROL METHODS
Benzene emissions can be controlled by adsorption with vapor recovery
or incineration. Emissions from storage tanks can be controlled through
the use of floating roof tanks or fixed roof tanks vented to an adsorp-
tion or incineration unit.
Although control equipment specifically for benzene emissions has not
been reported in the literature, devices for the control of other simi-
38
lar chemicals have been reported recently. Two types of control de-
vices are presently used in the manufacture of styrene: vapor recovery
and incineration. Both systems have the capability of controlling ben-
zene, toluene, and styrene emissions to approximately 100 percent.
Since these systems are currently being used by the styrene industry
and since benzene is closely related, it is assumed that the two control
systems can also be used in the production of benzene.
Adsorption
Control of hydrocarbon emissions by adsorption on activated charcoal is
generally applied when recovery o.f adsorbed material is economically
desirable. Adsorption should be used when concentrations of hydrocarbons
are greater than 2,500 ppm. Other applications include the control of
very low concentration hydrocarbons that are poisonous to catalytic in-
cinerators and collection and concentration of emissions for subsequent
disposal by incineration. Cost data for three cases utilizing adsorp-
tion are presented in Tables 6 and 7. The three cases are adsorption
with solvent recovery, adsorption with incineration and no heat recovery,
and adsorption with incineration plus heat recovery.
21
-------
Table 6. ESTIMATED INSTALLED COSTS OF ADSORPTION SYSTEMS'
Adsorber capacity, SCFM
With solvent recovery, $
With thermal incineration/
no heat recovery, $
With thermal incineration/
heat recovery, $
1,000
74,000
89,500
101,500
10,000
162,300
202,000
25,500
20,000
280,000
344,000
431,000
Reference 39. Inlet concentration assumed to be 25 per-
cent of lower explosive limit. Costs updated to first
quarter 1975.
Table 7. ESTIMATED ANNUAL OPERATING COSTS OF ADSORPTION
SYSTEMS3
Adsorber capacity, SCFM
With solvent recovery, $/yr
With thermal incineration/
no heat recovery, $/yr
With thermal incineration/
primary heat recovery, $/yr
1,000
13,200
23,400
25,600
10,000
-10,479b
64,300
82,000
20,000
-37,200b
123,200
141,600
aReference 39. Inlet concentration assumed to be 25 per-
cent of lower explosive limit. Costs updated to first
quarter 1975.
Indicates a savings as opposed to operating cost.
Incineration
Control of benzene emissions by incineration or catalytic oxidation in-
volves direct oxidation of the combustible portion of the effluent, the
desired ultimate products being water and carbon dioxide.
The primary advantage of catalytic incineration is that extremely dilute
concentrations of organics can be oxidized with only small amounts of
supplemental fuel required. The one main disadvantage is that certain
22
-------
hydrocarbons may poison the catalyst. Cost data for thermal and cata-
lytic incinerators with and without heat recovery are presented in
Tables 8 and 9.
Storage Tanks
Control of emissions from storage tanks would require the use of float-
ing roof tanks or venting the emissions to the previously mentioned
adsorber or incinerator. Emissions from fixed roof tanks can be vented
to either system without any major increase in cost. If these systems
are not available, the fixed roof tanks should be converted to floating
roof tanks, resulting in a 70 percent reduction'of emissions. Figure 2
39
provides estimated costs of various gasoline storage tanks. These
equipment cost estimates can also be applied to benzene. As can be seen,
conversion of fixed roof tanks by installation of internal floating covers
is much more economical than the installation of new floating roof tanks.
23
-------
Table 8. ESTIMATED INSTALLED COSTS OF THERMAL AND CATALYTIC
INCINERATORS3
Incinerator capacity, SCFM
Installed costs, $
Catalytic without heat recovery
Catalytic with primary heat
recovery
Catalytic with primary and
secondary heat recovery
Thermal without heat recovery
Thermal with primary heat
recovery
Thermal with primary and
secondary heat recovery
1,000
43,500
54,100
68,300
27,200
40,300
54,400
10,000
272,000
306,000
361,800
92,500
144,200
200,000
20,000
504,600
573,900
666,400
137,400
232,600
322,300
Reference 39. Inlet concentration assumed
of lower explosive limit. Costs updated to
1975.
to be 25 percent
first quarter
Table 9. ESTIMATED ANNUAL OPERATING COSTS OF THERMAL AND
CATALYTIC INCINERATORS3
Incinerator capacity, SCFM
Operating costs, $/yr
Catalytic without heat recovery
Catalytic with primary heat
recovery
Catalytic with primary and
secondary heat recovery
Thermal without heat recovery
Thermal with primary heat
recovery
Thermal with primary and
secondary heat recovery
1,000
16,200
16,400
19,300
12,000
11,500
14,400
10,000
102,800
78,500
108,700
54,300
36,300
50,800
20,000
195,000
177,900
203,700
96,700
59,200
84,500
Reference 39. Inlet concentration assumed
of lower explosive limit. Costs updated to
1975.
to be 25 percent
first quarter
24
-------
500
400
300
o
u
<
z
200
100
T I 1 I I I I I I I I I I I I I I T
Total Cost Cono Roof Tonic Converted
with Internal Floating Roof
Pontoon Floating
Roof Tank
Cone Roof Tank
Internal Float Cover on Existing Cone
Roof Tank (Incremental Cost - Conversion)
ol t t i
I t » I I I t I t I I I I I I
50 100
CAPACITY, barrels
150
200
Figure 2. Estimated installed cost of benzene storage tanks
(equipment costs assumed to be the same as gaso-
line storage tanks)39
25
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SECTION III
REFERENCES
1. Flury, F. and F. Zernik. Schadliche Case, Dampfe, Vebel, Rauch and
Staubarten, Spinger. Berlin, 1931. Cited in: Browning, E. Toxicity
and Metabolism of Industrial Solvents. Amsterdan, Elsevier Publish-
ing Co., 1965. p. 21.
2. Gerarde, H. W. The Aromatic Hydrocarbons. In: Industrial Hygiene
and Toxicology, Revised Edition, Patty, F. A. (ed.). New York,
Interscience Publishers, 1962. Vol. II. p. 1219-40.
3. Browning, E. Toxicity and Metabolism of Industrial Solvents.
Amsterdam, Elsevier Publishing Co., 1965. p. 3-65.
4. Tauber, J. B. Instant Benzol Death. J Occup Med. 12:520-23, 1970.
5. Winek, C. L. and W. D. Collom. Benzene and Toluene Fatalities.
J Occup Med. 13:250-261, 1971.
6. Criteria For a Recommended Standard: Occupational Exposure to
Benzene. HEW Publication No. (NIOSH) 74-137. 1974.
7. Fairhall, L. T. Industrial Toxicology. Second Edition. New York,
Hafner Publishing Co., 1969. p. 161-163.
8. Winek, C. L. Forensic Toxicology. In: Methods in Radioimmunoassay,
Toxicology and Related Areas, Vol 7. Progress in Analytical Chem-
istry, Simmons, I. L. and G. W. Ewing (eds.). New York, Plenum
Press, 1974. p. 122.
9. Stulman, A. and C. P. Stewart (ed.). Volatile Liquids. Toxicology:
Mechanisms and Analytical Methods, Vol. I. New York, Academic, Press,
1960. p. 61-63.
10. Oppelt, W. W. Toxicity from Exposure to Solvents. In: Laboratory
Diagnosis of Diseases Caused by Toxic Agents, Sunderman, F. W. and
F. W. Sunderman, Jr. (eds.). St. Louis, Warren H. Green, Inc., 1970.
p. 296-298.
26
-------
11. Aksoy, M., K. Dincol, S. Erdem and G. Dincol. Acute Leukemia Due
to Chronic Exposure to Benzene. Amer J Med. 52:160-166, 1972.
12. Forni, A., E. Pacifico and A. Limonia. Chromosome Studies in
Workers Exposed to Benzene or Toluene or Both. Arch Environ
Health. 22:373-378, 1971.
13. Forni, A., A. Cappellini, E. Pacifico and E. Vigliani. Chromosome
Changes and Their Evolution in Subjects With Past Exposure to Benzene.
Arch Environ Health. 23:383-390, 1971.
14. Forni, A. and L. Moreo. Cytogenetic Studies in a Case of Benzene
Leukemia. Europ J Cancer. 3:251-255, 1967.
15. The Toxic Substances List. 1974 Edition. HEW Publication No.
(NIOSH) 74-134.
16. Nau, C. A., J. Neal and M. Thorton. Cg - C^2 Fractions Obtained
from Petroleum Distillates. Arch Environ Health. 12:382-393, 1966.
17. Currier, H. B. Herbicidal Properties of Benzene and Certain Methyl
Derivatives. Hilgardia. 20:383-403, 1951.
18. Hindowi, I. J. Air Pollution Injury to Vegetation. National Air
Pollution Control Administration. Publication No. AP-70. 1970.
19. Brandt, C. S. and W. W. Heck. Effects of Air Pollutants on Vegeta-
tion. In: Air Pollution, Stern, A. Second Edition. New York,
Academic Press, 1968. p. 401-441.
20. Assessing Potential Ocean Pollutants. A Report of the Study Panel
on Assessing Potential Ocean Pollutants to the Ocean Affairs Board,
Commission on Natural Resources, National Research Council. National
Academy of Sciences, Washington, D.C. 1975.
21. Air Quality Criteria for Photochemical Oxidants. National Air Pollu-
tion Control Administration. Publication No. AP-63. 1970.
22. Haagen-Smit, A. J., E. F. Darley, M. Zaitling, H. Hull and W. Noble.
Investigation on Injury to Plants from Air Pollution in the Los
Angeles Area. Plant Physiol. 27:18-33, 1952.
23. Lonneman, W. A., T. A. Bellar and A. P. Altshuller. Aromatic Hydro-
carbon in the Atmosphere of the Los Angeles Basin. Environ Sci and
Technol. 2:1017-1020, 1968.
24. Pilar, S. and W. F. Graydon. Benzene and Toluene Distribution in
Toronto Atmosphere. Environ Sci and Technol. 7:628-631, 1973.
27
-------
25. Parkinson, G. S. Benzene in Motor Gasoline—An Investigation Into
Possible Health Hazards In and Around Filling Stations and In Normal
Transport Operations. Ann Occup Hyg. 14:145-153, 1971.
26. Turner, D. B. Workbook of Atmospheric Dispersion Estimates.
U.S. Environmental Protection Agency. Report No. AP-26.
April 1973.
27. Ruch, Walter E. Quantitative Analysis of Gaseous Pollutants.
Ann Arbor, Michigan, Ann Arbor-Humphrey Science Publishers, Inc.,
1970.
28. Analytical Abstracts. American Industrial Hygiene Association.
29. Hygienic Guide Series. American Industrial Hygiene Association.
30. NIOSH Manual of Analytical Methods. U.S. Department of Health,
Education and Welfare. National Institute for Occupational
Safety and Health, Cincinnati, Ohio, 1974.
31. Preliminary Report on U.S. Production of Selected Synthetic Organic
Chemicals. U.S. Trade Commission. February 1975.
32. Benzene Outlook. Hydrocarbon Processing. November 1974.
33. Chemical Economics Handbook. Stanford Research Institute, Menlo
Park, California. July 1974.
34. Development and Evaluation of a Transportation Control Plan for
Rhode Island, Volume I. Prepared by GCA/Technology Division,
Bedford, Massachusetts. Prepared for U.S. Environmental Protection
Agency, Region I, Boston, Massachusetts. Publication No. EPA-901/
9-75-003. September 1975.
35. Compilation of Air Pollutant Emission Factors. U.S. Environmental
Protection Agency. Report No. AP-42. April 1973.
36. Aldehydes and Reactive Organic Emissions from Motor Vehicles,
Part II: Characterization of Emissions from 1970, etc. Bureau
Of Mines. Publication No. APTD-1568-B. March 1973.
37. NPRA's 1973 Panel Views Processes. Hydrocarbon Processing.
March 1974.
38. Survey Reports on Atmospheric Emissions from the Petrochemical
Industry: Styrene. Volume IV. U.S. Environmental Protection
Agency. Publication No. EPA-450/3-73-005-d. April 1974.
39. Hydrocarbon Pollutant Systems Study. Volume I. MSA Research
Corp. October 1972.
28
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APPENDIX A
BENZENE PRODUCTION CAPACITY
33
Coal-derived benzene
Armco Steel
Bethlehem Steel
CF&I Steel
Interlake
Ling-Temco-Vought
Mead Corporation
Northwest Industries
Republic Steel
U. S. Steel
Total (coal-derived)
*
As of January 1, 1972.
Middletown, Ohio
Houston, Texas
Bethlehem, Penn.
Lackawanna, N. Y.
Sparrows Point, Md.
Pueblo, Colorado
Toledo, Ohio
Aliquippa, Penn.
Chattanooga, Tenn.
Woodward, Alabama
Lone Star, Texas
Cleveland, Ohio
Gadsden, Alabama
Youngstown, Ohio
Clairton, Penn.
Geneva, Utah
Capacity,
million gal/yr
2.5
0.9
5.7
7.5
15.0
3.0
1.8
10.0
0.2
1.4
1.4
6.6
1.2
3.6
40.1
4.0
104.9
29
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BENZENE PRODUCTION CAPACITY33 (continued)
Capacity,
million gal/yr
Petroleum-derived benzene
Allied Chemical Corp.
Amerada Hess Corp.
American Petrofina, Inc.
Ashland Oil, Inc.
Union Texas Petroleum
Division, Winnie, Texas
St. Croix, Virgin Islands
Big Spring, Texas
Ashland (Catlettsburg),
Kentucky
Tonawanda (Buffalo)',
New York
Atlantic Richfield Company Houston, Texas
Wilmington, California
Atlantic Richfield Company/ Nederland, Texas
Union Oil
Charter International Oil
Company
Cities Service Company,
Incorporated
Coastal States Gas Pro-
ducing Company
Commonwealth Oil Refining
Company
Crown Central Petroleum
Corporation
The Dow Chemical Company
Gulf Oil Corporation
Houston, Texas
Lake Charles, Louisiana
Corpus Christi, Texas
Penuelas, Puerto Rico
Houston, Texas
Bay City, Michigan
Freeport, Texas
Alliance, Louisiana
Philadelphia, Penn.
Port Arthur, Texas
23
30
60
25
44
16
18
25
10
160
30
40
70
33
38
As of January 1, 1972.
30
-------
BENZENE PRODUCTION CAPACITY33 (continued)
Petroleum-derived benzene
Marathon Oil Company
Mobile Oil Corporation
Monsanto Company
Pennzoil United, Inc.
Phillips Petroleum Company
Shell Oil Company
Skelly Oil Company
Southwestern Oil & Refin-
ing Company
Standard Oil Company of
California
Standard Oil Company
(Indiana)
Standard Oil Company
(New Jersey)
The Standard Oil Company
(Ohio)
Sun Oil Company
Detroit, Michigan
Texas City, Texas
Beaumont, Texas
Alvin (Chocolate Bayou),
Texas
Shreveport, Louisiana
Sweeny, Texas
Guayama, Puerto Rico
Deer Park, Texas
Odessa, Texas
Wilmington, California
Wood River, Illinois
El Dorado, Kansas
Corpus Christi, Texas
El Segundo, California
Texas City, Texas
Baton Rouge, Louisiana
Bay t own, Texas
Port Arthur, Texas
Marcus Hook, Penn.
Corpus Christi, Texas
Tulsa, Oklahoma
Capacity,
million gal/yr
6
6
60
75
12
22
110
65
5
20
40
12
8
15
85
60
60
15
15
15
12
As of January 1, 1972.
31
-------
BENZENE PRODUCTION CAPACITY33 (continued)
Petroleum-derived benzene
Tenneco Inc.
Texaco Inc.
Union Carbide Corporation
Union Oil Company of
California
Union Pacific Corporation
Total (petroleum-derived)
Grand total (coal- and
petroleum-derived benzene)
Chalmette, Louisiana
Port Arthur, Texas
Westville, New Jersey
Taft, Louisiana
Lemont, Illinois
Corpus Christi, Texas
Capacity,
million gal/yr
15
45
35
50
30
1542.0
1646.9
As of January 1, 1972.
32
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