U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
PB-256 736
Air Pollution Assessment
of Ethylene Dibromide
Mitre Corporation
Prepared For
Environmental Protection Agency
May 1976
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WASHINGTOr: OPERATIONS,
MTR-7222
CONTROLLED DISTRIBUTION
flir Pollution Assessment of Ethylene Dibromide
R. JOHNS
MAY 1976
mil
r ^ I I ^
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TECHNICAL REPORT DATA
'"'ease read Instructions on the reverse before completing)
1 REPORT NO
MTR-7222
3. RECIPIENT'S ACCESS!O.N>NO.
4 TITLE AND SUBTITLE
Air Pollution Assessment of Ethylene Dibromide
5. REPORT DATE
Mav 1976
6. PERFORMING ORGANIZATION CODE
7 AUTHOR(S)
R. 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
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
U.S. Environmental Protection Agency
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
14. SPONSORING AGENCY CODE
EPA-AWM
15 SUPPLEMENTARY NOTES
is.ABSTRAcr^Ethylene dibromide, a colorless, nonflammable hydrocarbon, is primarily
employed as an additive in leaded gasoline to scavenge lead oxide residues from the
combustion chambers of gasoline engines. Atmospheric measurements made near major
suspected emission sources (service stations, refineries, production facilities) re-
veal ethylene dibromide concentrations several orders of magnitude below the thres-
hold limit value of 25 ppm established by the American conference of Governmental
Industrial Hygienists. Ethylene dibromide generally acts as a central nervous system
depressant, although it is not as effective as many of the other halohydrocarbons.
In cases of death, pneumonia is normally the cause due to lung damange Induced by the
chemical. Symptoms of acute exposure include lung inflammation, congestion, edema,
and hemorrhaging. A significant environmental hazard does not appear to be present
in regard to ethylene dibromide; however, due to the lack of available data document-
ing long term, low level exposure 1n humans the compound cannot be considered environ-
mentally innocuous .^
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Organic Compounds
Organic Solvents
Physiological Effects
Air Pollution Control
Stationary Sources
Hydrocarbons
Air Pollution
13 DISTRIBUTION STATEMENT
19 SECURITY CLASS (Thu Report)
21. NO. OF PAGES
20 SECURITY CLASS (Thispage)
22.!
EPA Form 222O-I (9-73)
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CONTROLLED DISTR.
MITRE Technical Report
MTR-7222
flir Pollution flssessment of tthylene Dibromide
MITRI<:
MrlEAN VIRGINIA 22101
R. JOHNS
MAY 1976
CONTRACT SPONSOR US Environmental Protection Agency
CONTRACT NO 68021495
PROJECT NO 077 B
DEPT W-54
i CO
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Department Approval:
J. Golden
MITRE Project Approval:.
.L.Thomas
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ABSTRACT
Ethylene dibromide, a colorless, nonflammable hydrocarbon, is
primarily employed as an additive in leaded gasoline to scavenge lead
oxide residues from the combustion chambers of gasoline engines. In
the course of this application, the compound is combusted and the
bromine component of the compound is released to the atmosphere via
the automobile exhaust. Atmospheric measurements made near major
suspected emission sources (service stations, refineries, production
facilities) reveal ethylene dibromide concentrations several orders
of magnitude below the threshold limit value of 25 ppm established
by the American Conference of Governmental Industrial Hygienists.
Although the halohydrocarbon has been environmentally detected, it
does degrade slowly in the atmospheric and aquatic receiving environ-
ments with estimated respective half-lives of 100 days and 5 to 10
days. Therefore, no appreciable environmental accumulation would
be expected.
Ethylene dibromide generally acts as a central nervous system
depressant, although it is not as effective as many of the other
halohydrocarbons. In cases of death, pneumonia is normally the
cause due to lung damage induced by the chemical. Symptoms of acute
exposure include lung inflammation, congestion, edema, and hemorrhaging.
A significant environmental hazard does not appear to be present
in regard to ethylene dibromide; however, due to the lack of available
data documenting long term, low level exposure in humans the compound
cannot be considered environmentally innocuous.
iii
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ACKNOWLEDGEMENTS
The author wishes to acknowledge those individuals who con-
tributed time and effort during the one month preparation of this
document. Production statistics and control technology information
were contributed by L. Duncan and E. Preston provided the mathematical
calculations for the hypothetical atmospheric dispersion model. In
addition, B. Baratz, J. Golden, R. Ouellette, and L. Thomas, of The
MITRE Corporation provided guidance and suggestions, while R. Johnson,
M. Jones, and J. Manning of the U.S. Environmental Protection Agency
reviewed draft copies and assisted in the final version.
iv
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TABLE OF CONTENTS
I. SUMMARY AND CONCLUSIONS
II. AIR POLLUTION ASSESSMENT REPORT
A. PHYSICAL AND CHEMICAL PROPERTIES
B. EFFECTS
C. AMBIENT CONCENTRATIONS, POPULATION AT RISK AND
MEASUREMENT TECHNOLOGY
D. SOURCES
E. CONTROL STRATEGY
REFERENCES
Table Number
I
II
III
IV
LIST OF TABLES
ETHYLENE DIBROMIDE PHYSICAL PROPERTIES
ACUTE TOXICITY OF ETHYLENE DIBROMIDE
ATMOSPHERIC LEVELS - ETHYLENE DIBROMIDE
PRODUCTION PLANTS
ETHYLENE DIBROMIDE PRODUCTION LOCATIONS
Page
1
9
9
12
19
27
32
35
10
14
22
29
Figure Number
1
2
LIST OF FIGURES
ETHYLENE DIBROMIDE - PRODUCTION LOCATIONS
ETHYLENE DIBROMIDE - COMMERCIAL PATHWAYS
28
30
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I. SUMMARY AND CONCLUSIONS
Ethylene dibromide is a colorless, nonflammable liquid of high
density and chloroform-like odor. It is a good solvent for resins,
gums, waxes, and many organic chemicals, but its major use is as an
additive in leaded gasoline. The compound is miscible with benzene,
carbon tetrachloride, ether, alcohols, and many other solvents. The
low vapor pressure and appreciable water solubility of the compound
tend to promote environmental persistence in water and soil as well
as in the atmosphere.
Ethylene dibromide is inert at ordinary temperatures, but is
hydrolyzed to ethylene glycol and bromoethanol when heated with water.
The compound shows a half-life at 5 to 10 days toward hydrolysis under
neutral conditions at ambient temperature. This would tend to promote
limited persistence in the aquatic environment. Ethylene dibromide
is resistant to atmospheric oxidation by peroxides and ozone, typi-
cally showing half-lives in excess of 100 days toward these reactions.
The terminal halogen atoms of the molecule are moderately reactive
in synthesis, making the compound useful as an intermediate in the
production of other chemicals. It is the least expensive organic
bromine compound available.
Ethylene dibromide is readily absorbed through the lungs, skin
and gastrointestinal tract of mammals. It is excreted unchanged by
the lungs and is partially decomposed in the body, producing bromide
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residue in the urine. Pathological effects of the chemical are found
primarily in the liver, lungs, and kidneys of mammals.
Acute human toxicity of ethylene dibromide vapor is documented
primarily from accidents. The compound was mistaken for ethyl
bromide and administered as an anesthetic during earlier stages of
development of anesthesiology. Quantities up to 100 grams were ad-
ministered under these circumstances, resulting in irritation of the
larynx, conjunctivae, and lungs. Patients became weak, nervous,
pale, suffered vomiting and diarrhea, and died from circulatory
failure within 24 to 48 hours. Acute exposure of dogs to 50,000
3
mg/m vapor concentration for 15 to 45 minutes results in vomiting
and convulsions, cloudiness of the cornea, and death within 24 hours.
Mice survive a concentration of 10,000 mg/m for 30 minutes but die
from a 60-minute exposure at this level. Guinea pigs survive a
seven-hour exposure to 1,536 mg/m ethylene dibromide vapor but a
similar exposure to 31,000 mg/m is fatal. A significant toxicity
characteristic of ethylene dibromide is the relatively narrow margin
between recoverable and fatal exposures to the vapor.
Chronic exposure to ethylene dibromide vapor at concentrations
3
significantly above the threshold limit value (190 mg/m ) can pro-
duce symptoms similar to those of acute exposure. These effects
have been demonstrated using test animals as subjects. Rats exposed
3
for six months (35 hours/week) to 385 mg/m suffered 50 percent mor-
tality from pneumonia and respiratory infection, the survivors
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showing weight Increases in lungs, liver and kidneys. Guinea pigs
subjected to 57 seven-hour exposures in 80 days (385 mg/m vapor
concentration) showed reduced weight but normal mortality. Among
rats, rabbits and guinea pigs, rats showed the greatest respiratory
sensitivity to the chemical. Chronic vapor exposure results in
pathological damage to lungs, liver, kidneys and spleen of most
species.
Ethylene dibromide may be absorbed through the skin in suffi-
cient amounts to cause fatal poisoning. Rabbits died within four
days from the application of 1.0 g/kg-body-weight to shaved skin
for 24 hours. Skin absorption is a significant concern In the in-
dustrial environment, where workers' shoes may be splashed with the
chemical.
Acute oral toxicity of ethylene dibromide in humans is docu-
mented from the ingestion of 4.5 ml of the chemical in a suicide.
Symptoms of prolonged vomiting, diarrhea and anuria were followed
by death in 54 hours. Autopsy revealed massive liver and kidney
damage. Oral toxicity studies in animals reveal LD values ranging
from 0.055 g/kg-body weight in female rabbits to 0.420 g/kg-body
weight in female mice. Chronic oral doses of ethylene dibromide
have been shown to produce stomach cancer in mice and rats. When
administered chronically at one-half the maximum tolerated dose,
the compound induced a high incidence of squamous cell carcinoma
of the stomach in these animals within 10 weeks.
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Ethylene dibrotnide has been demonstrated to distinctly muta-
genic toward Salmonella typhemurium and Serratla marcescens by host-
mediated assay techniques in mice. The teratogenlcity of the
compound has not been reported. Dietary concentrations of 5 to 40
mg/kg in feed cause reductions in weight and fertility of eggs pro-
duced by laying hens. This finding is significant in that the chem-
ical is used for fumigation of feed grains. Repeated oral doses of
ethylene dibromide are found to cause malformations of the sperm in
bulls when administered at a level of 4 mg/kg-body-weight on alter-
nate days for three weeks.
In the aquatic environment, sunflsh and largemouth bass show
median 24-hour tolerance limits of 15 to 50 mg/kg ethylene dibro-
mide in river waters. Within this range, the results are influenced
by the source of the natural water sample.
Ethylene dibromide vapor is monitored in the industrial environ-
ment for compliance with Occupational Safety and Health (OSHA) reg-
ulations, which limit workplace atmospheres to 155 mg/m (20 ppm)
for eight-hour-average daily exposures. Measurements in the open
atmosphere are sparse. The Environmental Protection Agency (EPA)
has recently reported levels of 0.069 to 0.110 ng/m along urban
roadways in three western cities. Population exposure at the maxi-
mum level is such that 1,400 years would be required to accumulate
the occupational dose from a single day's work at the OSHA limit.
Therefore, these measurements indicate no risk to the exposed popu-
lation. Maxium levels of 90 to 115 |J.g/m were found on the premises
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of ethylene dlbromlde production facilities as a part of the same
study. These data were employed in a crude diffusion model, along
with hypothetical plant parameters, to predict downwind atmospheric
concentrations to which neighboring populations might be exposed.
A level of about 6 g/m was predicted for a point 500 meters down-
wind of one facility, assuming a wind velocity of 6 m/sec. An expo-
sure of 23 years to this concentration of ethylene dibromide is
equivalent in dose to an eight-hour day at the maximum legal work-
place concentration.
Potential exposure risks may stem from the use of ethylene
dibromide as a fumigant for soil and grain, a highly dispersive
application which is inherently difficult to control. Fumigation
of storage structures that are normally enclosed may expose workers
or any individuals in the vicinity to excessive levels of the air-
borne chemical. Exposure is possible in the distribution network
of gasoline since the material is employed as an additive in auto-
mobile fuel.
Ethylene dibromide is readily analyzed in air by gas chromato-
graphy, using an electron capture detector. This detector is selec-
tive toward halohydrocarbons and effective in attenuating background
response from other chemicals. A semi-quantitative test for ethylene
dibromide vapor may be made with the halide lamp detector, a simple
instrument which is specific for organic halogen compounds and
responds to ethylene dibromide at levels above 380 mg/m (50 ppm).
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Domestic production of ethylene dibromide totaled 331 million
pounds in 1973. The chemical is produced at six domestic facilities
which are clustered in the Gulf Coast region of the United States.
The chemical has shown an annual production growth of 3 to 5 percent
during the last decade, but future growth is uncertain. Ethylene
dibromide is used as an additive in leaded motor fuel, and this use
accounts for 85 percent of consumption. Production can be expected
to fall toward 15 percent of its projected current level once the
use of leaded gasoline is abandoned. Among other uses, about five
percent of ethylene dibromide consumption is used in the synthesis
of other organic chemicals and 10 percent is used dispersively as
a solvent and fumlgant. It is an ingredient in many commercial
insecticides, but is not otherwise sold as a comme.cial product.
There are no known natural sources of the chemical.
As a fuel additive, ethylene dibromide serves to scavenge lead
oxide residues from combustion chambers of gasoline engines through
conversion of the oxide to volatile lead bromide. While ethylene
dibromide undergoes combustion with the fuel, the bromine content
of the compound is emitted to the atmosphere as engine exhaust. A
major fraction of all bromine produced ultimately reaches the atmo-
sphere in this form.
Ethylene dibromide does not appear to be a substance with sig-
nificant environmental hazards. However, since little information
is available to assess potential long-term lew level effects or
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possible synergistic effects, the chemical cannot be considered
environmentally safe. Preliminary measurements of airborne ethylene
dibromide near major sources of suspected emissions (service stations,
highways, refineries, and production facilities) show levels of
ethylene dibromide which are several orders of magnitude below the
threshold limit value. Furthermore, it shows a reasonable tendency
to degrade in both atmospheric and aquatic receiving environments
with estimated half-lives of 100 days and 5 to 10 days, respectively.
No net environmental accumulation is suspected.
Major emission sources of ethylene dibromide which may be poten-
tial hazards are its dispersive uses in agriculture. It is employed
as a fumigant for soil and grain and as an ingredient in insecticides.
As such, it has been demonstrated to affect growth and behavior pat-
terns of several agricultural species. Residues of the material
have also been measured in some food products of exposed agricultural
produce.
It is recommended that ambient concentrations of ethylene dibro-
mide be measured near dispersal facilities to determine if harmful
quantities of the material are reaching all receiving environments
(air, water, soil). This would allow evaluation of the acceptability
of the material for these uses. If unacceptable levels are measured,
either substitute materials or improved dispersal techniques should
be developed.
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A study should be conducted to determine the extent and levels
to which ethylene dibrotnide occurs in food products. If significant
results are obtained, studies should be conducted to explore the
effect these levels of ethylene dibromide may have on populations
consuming these foodstuffs.
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II. AIR POLLUTION ASSESSMENT REPORT
A. PHYSICAL AND CHEMICAL PROPERTIES
Ethylene dibromlde is a dense, colorless, nonflammable
liquid resembling chloroform in odor, and possessing good solvent
properties for resins, gums, waxes and other organic compounds (1).
The principal physical properties of the compound are shown in Table
I. The low vapor pressure and appreciable water solubility of ethyl-
ene dibromide would tend to promote environmental persistence in
water and soil in cases of liquid spills. The bromohydrocarbons are
much less volatile than their chlorine analogs, and ethylene dibro-
mide solidifies at about 10°C. It is fully miscible with benzene,
carbon tetrachloride, ether, anhydrous alcohols and many other sol-
vents.
The compound is generally inert at normal temperatures, although
slight decomposition may result from exposure to light (1). It is
hydrolyzed to ethylene glycol and bromoethanol at elevated tempera-
ture. When heated to 340 to 370°C, ethylene dibromide decomposes
into vinyl bromide and hydrobromic acid. The terminal halogen atoms
are reactive, making the compound a useful synthetic intermediate.
It is the least expensive organic bromine compound available.
Ethylene dibromide is resistant to atmospheric oxidation by
peroxides and ozone, typically showing half-lives toward these
reactions of 100 days or more (2). The compound is generally less
reactive in the atmosphere than corresponding alkanes or olefins.
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TABLE I
ETHYLENE DlBROMIDE
Physical Properties
Chemical Formula
Molecular Weight
Boiling Point
Melting Point
Vapor Pressure, 25°C
Specific Gravity, liquid
Specific Gravity, vapor, 25 °C
Refractive Index 20°C
Solubility, water, 20°
Solubility, Octanol
Conversion Factors
@ 25°C/760 mm Hg
BrCH2-CH2Br
187.88
131.6°C
9.97°C
12 mm
2.17
6.5
1.5379
4.3 g/1
oo
1 mg/1 247 ppra
1 ppm 4.05 mg/m"
Source: Kirk, R. E., Encyclopedia of Chemical Technology, Second
Edition, Vol. 3, p. 771, New York, Wiley, 1968.
10
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Ethvlene dibromide is hydrolyzed in water, having a half-life of 5
to lO days toward this reaction; the reaction is favored by acid
conditions (2). Because of the paucity of data, it Is Impossible
to assess environmental accumulation of the chemical, but rates of
atmospheric degradation may be sufficient to handle the environmental
burden adequately.
11
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B. EFFECTS
Ethylene dibromide is readily absorbed through the lungs,
from skin contact, and through the gastrointestinal tract of mammals
(3, 4). The chemical shows a mild tendency for accumulation in brain
and liver tissue, as shown by experiments with laboratory animals
(4). It is excreted unchanged by the lungs and is partially decom-
posed in the body, producing bromide residue in the urine.
This chemical acts as a depressant to the central nervous sys-
tem in mammals, although it is relatively weaker in this effect than
other halohydrocarbons. Acute vapor exposure typically results in
lung inflammation, congestion, edema and hemorrhaging (3). Liver
damage is evidenced as cloudy swelling, fatty degeneration and necro-
sis; whereas, the kidneys show slight interstitial congestion and
edema. Deaths from acute exposure at high vapor concentrations are
usually due to pneumonia, developed as a result of lung injury (4).
Acute human toxicity of ethylene dibromide vapor is documented pri-
marily from accidents. At the turn of the century, the compound
was occasionally confused with ethyl bromide, and erroneously admin-
istered, and resulted in irritation of the larynx, conjunctivae,
and lungs. Patients became weak, nervous, pale, suffered vomiting
and diarrhea, and died from circulatory failure within 24 to 48
hours.
Animal studies have provided additional information on the
acute vapor toxicity of ethylene dibromide. Exposure of dogs to
12
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50 000 mg/m vapor concentration for 15 to 45 minutes resulting in
vomiting and convulsions, cloudiness of the cornea, and death within
24 hours (6). Selected data on the acute toxicity of ethylene di-
bromide to laboratory animals are shown in Table II. A significant
toxicity characteristic of ethylene dibromide is the relatively
narrow margin between recoverable and fatal exposures to the vapor.
i
This is demonstrated by experiments with mice, in which the animals
3
survived 10,000 mg/m vapor concentration for 30 minutes without
permanent damage, but died within 5 hours from a 60-minute exposure
at the same concentration (7).
Chronic exposure to ethylene dibromide vapor at concentrations
*
significantly above the threshold limit value (TLV) can produce
symptoms similar to those of acute exposure. The threshold limit
3
has been established at 190 mg/m (25 ppm) by the American Conference
of Governmental Industrial Hygenists (9). Because there is a narrow
margin between tolerable vapor concentrations of ethylene dibromide
and those causing severe injury, the threshold limit must be scrupu-
lously observed. Worker exposure is limited under Occupational 'Safety
3
and Health regulations to an 8-hour-average concentration of 155 mg/m
(20 ppm) (10).
The effects of chronic vapor exposure have also been demonstrated
using laboratory animals. Most species exposed to ethylene dibromide
*Airborne concentration which induces no physiological response
after repeated exposure.
13
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TABLE II
ACUTE TOXICITY OF ETHYLENE DIBROMIDE
Animal
Mouse
Mouse
Mouse
Mouse (female)
Rat (male)
Rat (female)
Guinea pig
Guinea pig
Guinea pig
Guinea pig
Rabbit
Rabbit
Rabbit (female)
Dog
Route
Inhalational
Inhalational
Inhalational
Oral
Oral
Oral
Inhalational
Inhalational
Inhalational
Oral
Epidermal
Epidermal
Oral
Inhalational
Dose
LCo
LC100
LC100
LC50
LC50
LC50
LC0
LCo
LC100
LD50
LD40
LD100
LD50
LD100
Dosage
10,000 mg/m
42,000 mg/m3
10,000 mg/m
0.420 g/kg-body wt.
0.146 g/kg-body-wt.
0.117 g/kg-body wt.
1,536 mg/ir3
3,074 mg/m3
31,000 mg/m3
0.110 g/kg-body-wt. -
0.30 g/kg-body-wt.
1.1 g/kg-body-vt .
0.055 g/kg-body-wt.
50,000 mg/m
Exposure
30 minutes
3 minutes
1 hour
7 hours
2 hours
6-18 hours
24 hours
24 hours
15-45 minutes
Reference
6
6
6 '
3
3
3
5
5
7
3
3
3
3
6
LC_—Survivable Concentration (concentration lethal to none of
a sample population under stated experimental conditions).
LCin_—Lethal Concentration (concentration lethal to 100 per-
cent of a sample under stated experimental conditions).
LD,—Dose lethal to 50 percent of a sample population under stated experimental conditions.
LD..Q—Dose lethal to 100 percent of a sample population under stated experimental conditions.
-------
vapor showed damage to lungs, liver, kidneys, and spleen (3). In an
extensive study, Rowe et al. (3) exposed various animals to vapor
3
concentra ions of 190, 385, and 770 mg/m of ethylene dibromide on
a schedule of 7 hours/day, 5 days/week for periods up to six months.
i
Rats and rabbits exposed to 770 mg/m concentration in this study
showed loss of weight, physical degeneration, and some deaths within
3
the first ten days of exposure. Rats exposed to 385 mg/m vapor
concentration showed 50 percent mortality from pneumonia and respira-
tory infection, but the survivors lived through the six-month
exposure. These survivors showed weight increases in lungs, liver
and kidneys, and histopathological changes in the lungs. Guinea pigs
3
subjected to 57 7-hour exposures in 80 days (385 mg/m vapor concen-
tration) showed reduced weight but normal mortality (3). A vapor
3
concentration of 190 mg/m (the threshold limit value) was well
tolerated by rats, guinea pigs, rabbits and monkeys. Rats showed
the greatest respiratory sensitivity among this group of animals.
Kochmann has described the overt symptoms of chronic vapor exposure
in cats and rabbits as sneezing, marked salivation, tremors and
incoordination (7).
A study, conducted by R. D. Short £t al. of the Midwest Research
Institute for the Environmental Protection Agency evaluated the
developmental toxicity of ethylene dibromide in rats and mice during
organogenesis. The experimental animals were bred and subsequently
exposed to atmospheric concentrations of 30 ppm ethylene dibromide
15
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for 23 hours each day during days 6 to 16 of the gestation period.
No significant mortality was observed in the adults exposed to the
compound; however, rat litter size was decreased and hydrocephaly
and minor costal anomalies were observed in the fetuses from the
exposed rats (8).
Ethylene dibromide may be absorbed through the skin in sufficient
amounts to cause fatal poisoning (11). Rabbits died within four
days as a result of the application of 1 g/kg body weight to shaved
skin for 24 hours (3). Skin absorption is a significant concern in
industry, particularly when vorV'rs' shoes may be splashed with the
chemical. Application of the undiluted chemical to the eye of
rabbits causes severe conjunctival irritation and very slight super-
ficial necrosis over a period of 48 hours (3).
Acute oral toxicity of ethylene dibromide in humans is documented
by a single case in which 4.5 ml of the liquid chemical was ingested
in a suicide (12). Ingestion was followed immediately by prolonged
*
vomiting and later by diarrhea, then anuria and death 54 hours after
poisoning. Autopsy revealed massive centrilobular necrosis of the
liver and proximal kidney damage (12). Acute oral toxicity of the
compound to laboratory animals is shown in Table II.
Chronic oral doses of ethylene dibronide have been shown to
produce stomach cancer in mice and rats (13). When administered
*Anuria - suppression or absence of urine.
16
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chro ically at one-half the maximum tolerated dose, the compound
induced z high incidence of squamous cell carcinoma of the stomach
within 10 weeks. Various quantities of ethylene dibromide resulted
in carcinomas in 76 percent of rats and 87 percent of mice (10).
Ethylene dibromide has been demonstrated to be distinctly
mutagenic in host-mediated assay in mice at a level of 500 mg/kg
serum concentration; back-mutations were detected using intraperitoneal-
injected suspensions of histidine-requiring Salmonella typhimurium
and leucine-requiring Serratia marcescens as mutants (14). Ethylene
dibromide showed no definite mutagenicity in a dominant lethal test
in mice (14).
Bulls have been found to be subject to sperm malformation as a
result of oral doses of ethylene dibromide of 4 mg/kg body weight
administered on alternate days for 3 weeks (15,16). Malformations
appeared about two weeks after the first dose and included total dis-
integration of sperm cells. Similar results were obtained when 120 mg
of the compound was injected into the fluid surrounding each testes of
bulls. The significance of the oral study stems from the general
use of ethylene dibromide as a fumigant for grain.
The effects of dietary ethylene dibromide on the growth of,
chicks and on the egg production of laying hens have been studied
(17,18). Chicks fed a diet containing 40 mg/kg concentration of the
compound showed reduced weight gains, reduced food consumption and
reduced feed efficiency. Kidney and liver tissues were found to
17
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contain bromides. Egg weights of laying hens were reduced significantly
by the presence of residual ethylene dlbromide In their diet of oats
(18). Levels as low as 5 mg/kg In feed were found to be toxic.
Another study confirmed that ethylene dibromlde was responsible for
reduction in the weight of hens' eggs, and that eggs from some hens
fed unspecified amounts of ethylene dibromlde were infertile (19).
These studies underline the need for caution in the use of the chemical
as a fumlgant for feed grains. Fumigation with ethylene dibromide
has also been shown to affect adversely the germination rate of seeds,
particularly under conditions of high humidity and temperature (20).
The toxicity of ethylene dibromide in the aquatic environment
has been s tudied using bluegill sunfish and largemouth bass as subjects
(21). The fish, of fingerling size, were exposed to various concen-
trations of the chemical in river water matrices. Sunfish showed
median tolerance limits of IS to 18 mg/kg concentration, whereas
bass showed median limits of 25 to 50 mg/kg under similar experimental
conditions. The experimental results were found to be somewhat
dependent on the source of the river water (21).
18
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C. AMBIENT CONCENTRATIONS, POPULATION AT RISK AND MEASUREMENT TECHNOLOGY
Ethylene dibromlde is controlled in industrial atmospheres
for purposes of occupational safety. Measurements of this chemical
in the ambient atmosphere are rare. A threshold limit value of
3
190 mg/m (25 ppm) vapor concentration has been established by The
American Conference of Governmental Industrial Hygenists. Occupational
3
Safety and Health regulations limit industrial atmospheres to 155 mg/m
(20 ppm) as an 8-hour average for daily exposures of workers (3).
Compliance data are not readily available, but industrial levels are
claimed to be maintained well below this limit.
The principal population exposure from ethylene dibromide
arises from dispersive uses of the chemical. The compound is used
as an additive in leaded gasoline, and this use accounts for 85 percent
of commercial demand. This application is not truly dispersive since
the compound ultimately undergoes combustion with the fuel, yet
ethylene dibromide may be lost to the environment throughout the
extensive production and distribution chain which serves the gasoline
market. The population risk from this source should be small, considering
the low vapor pressure of ethylene dibromide and its concentration of
about 0.05 percent by volume in fuel.
Preliminary measurements of atmospheric ethylene dibromide
at selected locations have recently been reported by the Environmental
Protection Agency (A). Sites were chosen near sources of the chemical
which are generally related to gasoline production, distribution and
use. Urban locations near arterial streets in three Western cities
19
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were chosen to represent worst-case ambient levels of ethylene dibro-
mide. These sites were located near roadways carrying traffic loads
of 25,000-50,000 vehicles per day, and each site was within 200-300
feet of two or more gasoline service stations. The sampling probes
were directed into the wind in each case and positioned 6 feet from
the ground. The results of the urban study are presented below.
ATMOSPHERIC CONCENTRATION OF ETHYLENE DIBROMIDE
Urban Roadway Sites
City Concentration, ug/m
Phoenix, Arizona 0.069
Los Angeles, California 0.11
Seattle, Washington 0.083
The observed concentrations are reasonably uniform between
the cities, considering the many variables involved, and are about
six orders of magnitude below the threshold limit value. An exposure
of about 1,400 years at a typical urban roadway site would be required
to accumulate the dose a worker receives at the OSHA limit in one
working day.
The atmospheric concentration of ethylene dibromide was also
measured at two locations on the premises of an oil refinery as a
part of the same study (4). Atmospheric levels ranged from 0.23 to
1.65 vig/m at locations 50-400 feet downwind of bulk transfer and
tank truck loading operations. While these concentrations range up to
20
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tenfold larger than urban roadway levels, they are still several orders
of u gnitude below levels considered hazardous. More than 100 years'
exposure on the premises of an oil refinery would be required to accumu-
late the occupational dose from a single day's work at the maximum legal
concentration.
Atmospheric levels of ethylene dibromide were also measured at
production facilities of two major manufacturers of the chemical (22).
Maximum levels of 90-115 pg/m were recorded at downwind locations
near the perimeters of these properties, as detailed In Table III.
While these levels are significantly larger than those observed at
roadway or refinery sites, a calculation shows that a 17-month exposure,
at a representative level of 100 ug/m , would be required to equal the
occupational dose from a single 8-hour day at the OSHA limit of 155 mg/m .
The atmospheric concentrations of ethylene dibromide at
*
production facilities may be used in a Gaussian plume equation
Ground level downwind concentrations resulting from a point source
are predicted by the following equation:
« 0; H) =
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 con-
tra t ion Is being computed (meters)
a - vertical dispersion coefficient evaluated in terms of
downwind distance to the point for which the concen-
tration is being computed (meters)
X = ground level concentration on plume axis (grams/meter )
21
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TABLE III
ATMOSPHERIC LEVELS-ETHYLENE DIBROMIDE PRODUCTION PLANTS
Facility
Dow Chemical Magnolia, AR
Ethyl Corporation
Magnolia, AR
Maximum Level**
115 ug/m, 76 m downwind
90 ug/m
30 m distant
45° from downwind
Emission Rate
0.00862 g/sec
5.097 g/sec
Estimated Level*
6.26 ug/m
356 ug/m3
NJ
to
Source: U.S. Environmental Protection Agency. "Sampling and Analysis of Selected Toxic Sub-
stances. Task II—Ethylene Dibromide." Final Report, September, 1975, EPA 560/6-75-001.
*Estimated level 500 m downwind, wind at 6 m/sec.
-------
to Turner (23) fo predict downwind atmospheric levels of
the chemical in surrounding neighborhoods. The basic diffusion
equation must be modified, however, due to the effect of the plant
itself on the flow of air. Mechanical turbulence in the wake of a
building tends to produce aerodynamic downwash, 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 proposed that a modifi-
cation 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, analogous to the
situation wherein a plume is trapped below an inversion layer. A
limited vertical mixing height can be modeled using the equation:
*(x'°'z; H) - noyi (.8L)
where L is the 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 to an area source
emission with the area equal to the building top. This can be modeled
using a further modification of the basic Gaussian diffusion equation.
23
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A virtual point source is assumed upwind of the building at a distance
where the plume spread (for the given stability conditions) would equal
the crosswind width of the building. The modified diffusion equation is,
therefore:
X(x'°'z; H>
where h Is the building height and o' is based on the downwind dis-
tance to the receptor point, plus the upwind distance to the virtual
point source.
The measured atmospheric levels of ethylene dibromide at
the two production facilities were used in the foregoing equation
to determine mass emission rates, Q, from the two plants. These rates
were then used in the diffusion equation to estimate concentrations
at points 500 m downwind of the plants under an assumed wind velocity
of 6 m/sec. The results are shown in Table III. Acute toxicity
of ethylene dibromide levels near the two facilities are seen to differ
by about fifty fold, a rather surprising range. The downwind con-
centration estimate for the Dow facility is considered the more
credible value since it Is based on a chemical measurement at a point
directly downwind of the plant. Population exposure to this con-
centration of ethylene dibromide at a distance of 500 meters from the
plant is such that a 23-year exposure would be equivalent in dose
to an 8-hour working day at the maximum occupational level.
-------
Limited measurements of ethylene dibromide in runoff water
were made at two sampling sites as part of the aforementioned
EPA study (4). Samples from an ethylene dibromide manufacturing
facility and from the bulk loading area of a petroleum refinery
showed similar concentrations of about 1 ug/1. The samples were
taken from small streams within the respective premises. In one
case, the runoff stream is directed to a biodegradation pond for
further treatment.
Potential population risks may stem from the use of ethylene
dibromide as fumigant for soil and grain. The chemical is used
for the control of wire worms and nematodes in soil, and for
insect control in grain storage facilities. While these appli-
cations account for a small fraction of ethylene dibromide con-
sumption, they are totally dispersive, and offer paths to the
soil as well as to the aquatic and atmospheric environment.
Although no quantitative data are available*, it can be envisioned
that control of fumigant applications is difficult and they entail
the risk of both occupational and residential exposure. Fumigation
i
of grain storage structures may expose workers, bystanders and neigh-
boring residents to excessive atmospheric concentrations of the
chemical. Ethylene dibromide is also used industrially as a specialty
solvent, but is not sold as a consumer product.
Ethylene dibromide, as other halohydrocarbons, is readily
analyzed in air by means of gas chromatography using an electron
25
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capture detector (24). This detector is selective toward organic
halogen compounds and effective in attenuating background response
from other chemicals. Other methods depend on oxidation or hydrolysis
of ethylene dibromide and subsequent quantitative determination of
inorganic bromide by conventional wet analysis. Such methods are
more time-consuming than chromatography but are useful In laboratories
that lack chromatographic equipment. Airborne ethylene dibromide
responds to the halide lamp detector (Beilstein test). This simple
and inexpensive detector is specific for organic halogen compounds,
but does not distinguish among them. The halide lamp is in common
use for the detection of fluorocarbon leaks from refrigeration
systems, and provides a qualitative or semi-quantitative indication
of the presence of halohydrocarbons at the detection level of the
instrument, usually about 50 ppm or 380 rag/m of ethylene dibroraide.
26
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D. SOURCES
Ethylene dibromide is a major industrial chemical by virtue
of its use in leaded motor fuel, which accounts for 85 percent of
demand. Domestic production of the chemical by direct combination of
ethylene and bromine totaled 331 million pounds in 1973 (25). The
chemical has shown strong long-term growth, which has leveled to an
annual rate of 3 to 5 percent over the last decade (25). Production
can be expected to fall toward 15 percent of its projected current
level as leaded fuel approaches obsolescence. Ethylene dibromide
is produced at six domestic facilities which are generally clustered
in the Gulf Coast region, as shown in Figure 1; detailed plant loca-
tions are given in Table IV. The Gulf region is favored because its
brine fields provide the bromine supply needed in the synthesis of
ethylene dibromide. Furthermore, the complex of petroleum refineries
in the region provides the major commercial market for the chemical.
The flow of ethylene dibromide in commerce is depicted in
Figure 2. Foreign trade plays a minor role in the supply of this
chemical. The data of Figure 2 indicate that about 36 million pounds
of the chemical, or 11 percent of production, are released to the
environment per year, exclusive of fuel losses, which are discussed
below. There are no known natural sources of the chemical.
As a fuel additive, ethylene dibromide serves to scavenge lead
oxide residues from combustion chambers of gasoline engines through
conversion of the oxide to volatile lead bromide. Lead oxide residues
27
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FIGURE 1
ETHYLENE DIBROMIDE PRODUCTION LOCATIONS
ro
CO
Source: Stanford Research Institute, Chemical Economics Handbook.
-------
TABLE IV
ETHYLENE DIBROMIDE PRODUCTION LOCATIONS*
Company
Location
Dow Chemical, U.S.A.
Ethyl Corporation
Great Lakes Chemical Corporation
Northwest Industries
PPG Industries
Magnolia, Ark.
Midland, Mich.
Magnolia, Ark.
El Dorado, Ark.
El Dorado, Ark.
Beaumont, Tex.
Source: Stanford Research Institute, Chemical Economics Handbook.
^Capacities not available.
29
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FIGURE 2
ETHYLENE DIBROMIDE-COMMERCIAL PATHWAYS
TOTAL U.S.
PRODUCTION
331.1
Million Lbs/Year
|
RODUCTION LOSSES 1.5
5.0
Million Lbs/Year
IMPORTS EXPORTS
(Negligible)
1 A
1 t
TOTAL U.S.
^ CONSUMPTION
326.1
Million Lbs/Year
1
I DISTRIBUTION LOSSES
(Not Available)
Dispersive Uses 95%
309.8 Million Lbs/Year
Captive Uses 5%
16.3 Million Lbs/Yr
i
LEAD SCAVENGER
977 9
f. 1 1 . £
Million Lbs/Year
FUMIGANT
1 c.
J. . 0
Million Lbs/Year
SOLVENT, OTHER
9Q "\
£7 . J
Million Lbs/Year
SYNTHETIC INTERMEDIATE
\ f *>
lo.J
Million Lbs/Year
-------
re"'-'" from the use of fuels containing tetraalkyl lead compounds as
anti-knock agents. Since ethylene dibromide undergoes combustion
with the fuel, this application is dispersive only with respect to
losses which occur in the distribution and handling of gasoline. As
a consequence of combustion, the bromine content of the chemical is
released to the atmosphere as lead bromide through engine exhaust.
A major fraction of all bromine produced reaches the atmosphere in
this form. This is a declining problem, however, since ethylene
dibromide will be eliminated from gasoline as the use of leaded fuel
is abandoned.
Ethylene dibromide is a useful synthetic intermediate and the
most widely used bromine compound available. It is used in the
synthesis of dyes, Pharmaceuticals and other organics, but these
applications account for only 5 percent of demand. These uses are
totally non-dispersive, and probably do not lead to formation of
reaction products which pose significant problems as environmental
contaminants.
The compound is also used as a fumlgant for soil and grain, and
as an ingredient in many commercial insecticides. These applications
are highly dispersive and potentially hazardous from the standpoint
of occupational and population exposure. Ethylene dibromide is used
as a specialty solvent for resins, gums and waxes, but presumably
under industrial conditions of controlled risk. The compound is not
available as a consumer product.
31
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E. CONTROL STRATEGY
Ethylene dibromide is a major industrial chemical whose use
in motor fuel subjects the compound to broad distribution in the
environment at low concentrations. Preliminary measurements of
airborne ethylene dibromide near production facilities, refineries,
and roadways, show levels which appear clearly free of population
risk. The data indicate that no additional control is needed to
restrict population exposure from these sources. Because of the
low vapor pressure of the chemical and its small concentration in
fuel (0.05%), hazardous local excesses are unlikely to occur in
normal handling of gasoline. Fuel-related sources of ethylene
dibromide are, moreover, in a position of diminishing importance,
since this use of the chemical will disappear as leaded gasoline
reaches obsolescence.
The uses of ethylene dibromide as a fumigant and solvent
are highly dispersive and may entail risks to workers, bystanders,
and localized population segments. The chemical is a component of
many commercial insecticides. While solvent applications are
probably confined to the industrial environment, fumigation opera-
tions are carried out under field conditions where control may be
lax or difficult. Because of its low vapor pressure, ethylene di-
bromide is a persistent chemical, and the fumigation of enclosed
spaces may entail risks to those entering later. Control of these
applications is largely dependent on personnel training and product
32
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application data. Legislative control can be assured only through
restrictions on the sale and use of the material.
There are no data available on atmospheric accumulation of
ethylene dibromide. As with other chemicals, it would be valuable
and interesting to balance the rate of loss to the atmosphere against
the assimilative capability of the atmosphere for this chemical, but
this is a formidable task. Judging from available literature, there
seems a general consensus that significant accumulation of ethylene
dibromide in the atmosphere is unlikely.
33
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