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AIR POLLUTION ASPECTS
OF
BORON AND ITS COMPOUNDS
Prepared for the
National Air Pollution Control Administration
Consumer Protection & Environmental Health Service
Department of Health, Education, and Welfare
(Contract No. PH-22-68-25)
Compiled by Norman L. Durocher
Litton Systems, Inc.
Environmental Systems Division
7300 Pearl Street
Bethesda, Maryland 20014
September 1969
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FOREWORD
As the concern for air quality grows, so does the con-
cern over the less ubiquitous but potentially harmful contami-
nants that are in our atmosphere.
been identified, and available information has been summarized
Thirty such pollutants have
in a series of reports describing their sources, distribution,
effects, and control technology for their abatement.
30 pollutants.
A total of 27 reports have been prepared covering the
These reports were developed under contract
(NAPCA) by
for the National Air Pollution Control Administration
Litton Systems, Inc.
The complete listing is as follows:
Aeroallergens (pollens)
Aldehydes (includes acrolein
and formaldehyde)
Ammonia
Arsenic and Its Compounds
Asbestos
Barium and Its Compounds
Beryllium and Its Compounds
Biological Aerosols
(microorganisms)
Boron and Its Compounds
Cadmium and Its Compounds
Chlorine Gas
Chromium and Its Compounds
(includes chromic acid)
Ethylene
Hydrochloric Acid
Hydrogen Sulfide
Iron and Its Compounds
Manganese ang Its Compounds
Mercury and Its Compounds
Nickel and Its Compounds
Odorous Compounds
Organic Carcinogens
Pesticides
Phosphorus and Its Compounds
Radioactive Substances
Selenium and Its Compounds
Vanadium and Its Compounds
Zinc and Its Compounds
These reports represent current state-of-the-art
literature reviews supplemented by discussions with selected
knowledgeable individuals both within and outside the Federal
Government.
They do not however presume to be a synthesis of
available information but rather a summary without an attempt
to interpret or reconcile conflicting data.
The reports are
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necessarily limited in their discussion of health effects for
some pollutants to descriptions of occupational health expo-
sures and animal laboratory studies since only a few epidemio-
logic studies were available.
Initially these reports were generally intended as
internal documents within NAPCA to provide a basis for sound
decision-making on program guidance for future research
activities and to allow ranking of future activities relating
to the development of criteria and control technology docu-
ments.
However, it is apparent that these reports may also
be of significant value to many others in air pollution control,
such as State or local air pollution control officials, as a
library of information on which to base informed decisions on
pollutants to be controlled in their geographic areas.
Addi-
tionally, these reports may stimulate scientific investigators
to pursue research in needed areas.
They also provide for the
interested citizen readily available information about a given
pollutant.
Therefore, they are being given wide distribution
with the assumption that they will be used with full knowledge
of their value and limitations.
This series of reports was compiled and prepared by the
Litton personnel listed below:
Ralph J. Sullivan
Quade R. Stahl, Ph.D.
Norman L. Durocher
Yanis C. Athanassiadis
Sydney Miner
Harold Finkelstein, Ph.D.
Douglas A. Olsen, PhoD.
James L. Haynes
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The NAPCA project officer for the contract was Ronald C.
Campbell, assisted by Dr. Emanuel Landau and Gerald Chapman.
Appreciation is expressed to the many individuals both
outside and within NAPCA who provided information and reviewed
draft copies of these reports.
Appreciation is also expressed
to the NAPCA Office of Technical Information and Publications
for their support in providing a significant portion of the
technical literature.
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ABSTRACT
Certain compounds of boron are toxic air pollutants to
humans and animals.
Inhalation of boron compounds as dusts
can be moderately toxic, causing irritation and inflammations
but without permanent injury.
Inhalation of boron hydrides
(boranes, used as high-energy fuels) can be highly toxic,
producing signs of severe central nervous system damage, and
is capable of causing death through exposure to high concen-
trations for relatively short periods of time.
Boron acts
as an herbicide when applied to plant life in more than
minute quantities, but is not known to affect materials.
The use of boron as an additive in petroleum fuels,
and as a source of high-energy fuel, its presence in coals,
and the manufacturing processes employed to produce boron
compounds are believed to be limited sources of atmospheric
boron.
No information was discovered on concentrations of
boron in the atmosphere.
No information has been found on the economic costs of
boron air pollution or on the costs of its abatement.
Methods
of analysis are available; however, they are not sufficiently
sensitive or selective for determining atmospheric concentra-
tions of boron and its compounds.
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CONTENT S
FOREWORD
ABSTRACT
10 INTRODUCTION . . . 1
2. EFFEcrS . 2
201 Effects on Humans . 2
2.1.1 Boranes . 2
2.1.2 Boric Acid, Sodium Borates, and
Boron Oxide 3
2.1.3 Other Boron Compounds . 4
2.2 Effects on Animals . . 4
2.2.1 Commercial and Domestic Animals . 4
2.2.2 Experimental Animals 5
2.2.2.1 Boranes . . 5
2.2.2.2 Boric Acid, Sodium Borates
and Boron Oxide . 5
2.2.2.3 Other Boron Compounds 6
2.3 Effects on Plants . 6
2.4 Effects on Materials 0 7
2.5 Environmental Air Standards 7
3. SOURCES . 9
3.1 Natural Occurrences . 9
3.2 Production Sources . 10
3.3 Product Sources . 0 . 11
3.301 Boron Oxide, Boric Acid, and Borates 12
3.3.1.1 Boric Acid . . . . 12
3.3.1.2 Borax . . . . . 13
3.3.103 Other Borates . 0 14
3.3.2 Boric Acid Esters . . . 14
3.3.3 Refractory Boron Compounds . 15
3.3.4 Boron Halides . . 15
3.3.5 Boron Hydrides . . . 16
3.305.1 Diborane (B;? H6) . . . . 16
3.3.5.2 Tetraborane ( B 4 HI 0 ) 16
3.3.5.3 Pentaborane (Bs Hg ) . 17
3.3.5.4 Decaborane (BI 0 HI 4 ) . 17
3.4 Environmental Air Concentrations g 18
4. ABATEMENT
5. ECONOMICS
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CONTENTS (Continued)
6.
METHODS OF ANALYSIS. .
7.
SUMMARY AND CONCLUSIONS.
. . . . . . . . . . .
. . . .
. . .
REFERENCES
APPENDIX
. . .
. . .
. . .
21
24
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10.
LIST OF TABLES
1.
Probable Results of Single Exposure to Pentaborane
Va par s . . . . . . . . . . . . . . . . . . . . . . .
2.
Acute Oral and Parenteral Toxicity of Boranes
. . .
3.
Acute Inhalation Toxicity of Boranes . . . . .
. . .
4.
Acute Oral and Parenteral Toxicity of Boric Acid. .
5.
Acute Oral and Intravenous Toxicity of Sodium
Barates .. . . . . .. . . . . . . . . . . . .
. . .
6.
Acute Oral Toxicity and Eye Irritation of Borane
Ester s . . . . . . . . . . . . . . . . . . . . . . .
7.
Acute Toxicity of Organoboron Compounds
. . .
. . .
8.
Acute Inhalation Toxicity of Boron Halides.
. . . .
9.
Acute Oral and Parenteral Toxicity of Miscellaneous
Boron Compounds. . . . . . . . . . . . . . . . . .
Properties, Toxicity and Uses of Boron and Some
Boron Compounds. . . . . . . . . . . . . . . . . .
31
32
34
35
36
37
38
42
42
43
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1
1.
INTRODUCTION
Boron and its compounds have presented hazards to the
health of humans and animals, and therefore should logically
be investigated as a cause of environmental contamination.
The most common health hazards have been the accidental inges.
tion of household chemicals, such as boric acid or borax, and
absorption of boric acid from wounds or burns; these hazards,
of course,
are not directly relatable to environmental pollu-
tion.
A less common hazard is the contamination of the atmo-
sphere by boron dusts, mainly produced during the manufacture
of boron compounds and products.
The most serious hazard is
the danger of atmospheric contamination by boron hydrides, or
boranes--highly-toxic compounds used as high-energy fuels for
rocket motors and jet engines.
The use of boron as a fuel
additive in the petroleum industry undoubtedly contributes to
boron air pollution; however, its impact is unknown.
No data are available on the concentrations of boron
in the atmospheric environment, and no measurements of this
element or its compounds are known to be included in current
air-monitoring programs.
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2
2.
EFFEcrS
2.1
Effects on Humans
31
Boron and its compounds are considered by Sax
as
m8derately to highly toxic to man, through ingestion or
inhalation.
The most significant of the boron compounds
related to air pollution are the boron hydrides (boranes),
which are rated by Sax as highly toxic; these compounds, used
as high-energy fuels, can cause air pollution when allowed to
escape into the atmosphere, and can produce severe central
nervous system irritation when inhaled, possibly causing
death or permanent injury.
Other compounds of boron are not
highly toxic, and therefore are not considered industrial
poisons.
However,
inhalation of these compounds (such as
boron oxide, boric acid, etc.) in the form of dusts can be
moderately toxic without causing death or permanent injury.
2.1.1
Boranes
The boranes, the most highly toxic of the boron com-
pounds, consist chiefly of pentaborane, decaborane, and
diborane.
Others are known and still others are being devel-
oped, but at this time these are the most significant.
Of
these, pentaborane is the most toxic, while decaborane and
diborane are only slightly less so"
Instances of human
exposure to these compounds have occurred; however, adequate
data were not available to ascertain the concentration or the
actual nature of the particular compound.
Rozendaal, in 1951,
29
reported a syndrome resembling metal fume fever after expo-
sure to diborane while exposure to pentaborane produced marked
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3
central nervous system irritation.
Diborane produces chest
tightness. cough, headaches, nausea, chills, drowsiness, and
dizziness.
These symptoms appear promptly and last a rela-
tively short time.
Pentaborane produces the same symptoms,
but with more pronounced dizziness, headache, and drowsiness.
Convulsions, semicoma, disorientation. a persistent leukocy-
tosis, and signs of liver damage were reported in one extreme
case of pentaborane intoxication.
The incidence of acute borane intoxication in humans
has been low despite the number of persons who have worked
with and around these compounds.
This is largely attributable
to the safety procedures employed to avoid inhalation. skin
contact, and ingestion of boron compounds.
Table 1 in the Appendix indicates probable results
from a small exposure to pentaborane vapors for various time
periods.
2.1.2
Boric Acid, Sodium Borates, and Boron Oxide
31
These compounds are not considered by Sax to be
highly toxic: however, under certain circumstances they do
possess a moderate degree of toxicity.
Sax rates them gener-
ally as moderately toxic when ingested or inhaled, with the
most common danger to health occurring through accidental
ingestion.
The medical literature contains many instances of
accidental poisoning due to ingestion of borates or boric
acid.
While it has been contended that death may result from
the ingestion of 15 to 30 g of borax or 2.5 g of boric acid.
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4
33
Vertan
in 1929 reported administering doses of 15 to 30 g
of boric acid to several hundred humans without serious
effects.
Borax soap mixtures have been in use for many years,
and mild solutions of boric acid have been used routinely as
an eye wash.
However, Sax cautions that the careless use of
borax as a skin cleanser should be discouraged, as well as
the continuous use of boron solutions for irrigation of body
cavities.
2.1.3
Other Boron Compounds
No evidence is available concerning the toxicity of
other boron compounds.
Boron carbide and boron nitride can
. 31
possibly be considered as nUlsance dusts.
2.2
Effects on Animals
2.2.1
Commercial and Domestic Animals
No record has been found of accidental boron intoxica-
tion in livestock.
28
Owen reported in 1944 on the experimental
dosing of two dairy cows which were alternately fed a control
ration of 16 ppm boron and a ration containing 1 percent borax
(283 ppm boron) over periods of 42 days.
No ill effects were
noted, and no decrease in milk output resulted.
Of the
ingested borax, 98 percent was excreted, and the remaining 2
percent appeared in the milk.
The boron concentration of the
milk rose from a normal level of 0.7 ppm to 2 ppm as a result
of the experiment.
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5
2.2.2
Experimental Animals
2.2.2.1
2
Boranes
Experiments with the boranes on animals have indicated
the highly toxic nature of these compounds.
Internal adminis-
tration of pentaborane has produced death, preceded by list-
lessness, incoordination, tremors, convulsions, and coma.
Inhalation of highly concentrated diborane produced death of
hamsters within 25 minutes.
Small quantities (0.2 ml) of
borane fuel administered to the eyes produced severe eye
irritation in rabbits.
Tables 2 and 3 in the Appendix present data on the
toxicity of the boranes.
2.2.2.2
'd 2
Boric Acid, Sodium Borates, and Boron OXl e
Studies of animals experimentally dosed with boric
acid have revealed that this compound can be regarded as
moderately toxic to all species of animals.
Acidic solutions
of 5 percent boric acid were nonirritating to eye and skin,
while alkaline solutions produced a slight irritation which
subsided within hours without residual injury.
Boron oxide
applied to the skin of a rabbit produced reddening of the
. 2
Levlnskas cites several labora-
skin, but no other symptoms.
tory experiments in which boron compounds were administered
to animals by inhalation without serious injury.
In one
instance, borax particles 5 ~* or less in diameter were
administered to the lungs of guinea pigs three times daily on
alternate days, with total dosage amounting to 150,000 ~g.
*~: micron(s).
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6
No damage to the lungs resulted.
In another case, rats and
guinea pigs were exposed to an atmosphere containing boron
oxide particles for 6 hours per day over a period of 6 weeks.
No ill effects were noted even with exposure to 40,000 ~g/m3
boron oxide.
Table 4 in the Appendix presents data on the toxicity
of boric acid, and Table 5 in the Appendix lists data on the
toxicity of sodium borates.
2.2.2.3
Other Boron Compounds
Organic compounds such as borate esters were found to
be moderately toxic to experimental animals when ingested or
when applied to the skin; experiments involving mice produced
acutely toxic reactions.
However, inhalation of vapors pro-
duced no ill effects.
Table 6 in the Appendix lists toxic effects of the
borate esters; Table 7, (Appendix) data on organoboron com-
pounds; Table 8 (Appendix) the toxicities of the boron halides;
and Table 9 (Appendix) data on other miscellaneous compounds.
Additional data on characteristics and toxicities of boron
compounds can be found in Table 10 in the Appendix.
2.3
Effects on Plants
Small quantities of boron are required for all plant
life, and borates are accordingly found in commercial fertiliz-
ers. However, large quantities are extremely toxic, and boron
12
can therefore be used as an effective herbicide.
Due to its
destructive effect on vegetation, boron used as an herbicide
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7
does not appear to playa significant role in accidental
poisoning of animals.
Many treatises have been prepared on the boron needs
f 1, 10
o p ant l~fe; Brenchley covered the subject well in the
Botanical Review in 1947.
2.4
Effects on Materials
No information has been found indicating that damage
to materials results from the presence of atmospheric boron.
2.5
Environmental Air Standards
, , 17 h
The American Industrial Hygiene Assoc~at~on as pre-
pared guides for diborane and pentaborane.
The Manufacturing
23
Chemists Association has prepared a Chemical Safety Data Sheet
on boron hydrides.
However, the most recent standard for these
compounds was issued by the American Conference of Governmental
5
Industrial Hygienists in 1967.
Threshold Limit Values (TLV) for these compounds are:
Diborane 0.100 ppm (100 ~g/m3)
Pentaborane 0.005 ppm (10 ~g/m3)
Decaborane 0.050 ppm (300 ~g/m3)
The median concentrations detectable by odor for man
are 3.3 ppm (33,000 ~g/m3) for diborane, 0.8 ppm (1,600 f-lg/m3)
for pentaborane, and 0.7 ppm (4,200 ~g/m3) for decaborane.
These values are obviously considerably greater than the
established TLV-
Hygienic standards for brief exposures have not been
established.
However, the American Industrial Hygiene Associa-
t' 18
~on has suggested an Emergency Exposure Limit for penta-
borane of 25 ppm (50,000 ~g/m3) for not over 5 minutes.
Since
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8
this value permits a degree of intoxication, it does not
represent a completely safe limit of exposure.
This
same
source states that exposure to 1,000 ppm (2,000,000 ~g/mC)
for one minute is believed to cause convulsions, and in some
cases
death.
The American Conference of Governmental Industrial
Hygienists in 1967 adopted a value of 15,000 ~g/m3 as the
TLV for boron oxide. No TLV has been established for boric
. . 16
acid dust, but Hyatt and Mllllgan suggest that the concen-
tration be kept below 2,000 ~g/m3.
No information has been found regarding environmental
standards for continuous exposures over longer periods than
mentioned above.
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9
3.
SOURCES
3.1
Natural Occurrence
only an
Boron is widely distributed in nature, but constitutes
19
estimated 0.001 percent of the earth's crust. It
is also present in sea water, and appears to be an essential
constituent of a number of rock-forming silicate minerals,
such as datolite and tourmaline.
Boron occurs naturally only
in combined forms, usually as an alkaline earth borate or as
boric acid.
Although boron is widespread in nature, large deposits
of commercially valuable boron minerals are found only in a
very few localities, and these are primarily areas of formerly
intense volcanic activity where precipitation and natural
drainage have not produced leaching and drainage to the sea.
The United States supplies most of the boron minerals required
by the free world.
The Kramer deposit, located near the town
of Boron, Calif., contains an estimated 100,000,000 tons of
borax and kernite, and is the principal source of borate.
The
remainder of the borax produced in this country comes almost
entirely from Searles Lake, near Trona in the Mohave Desert,
although minor deposits are located elsewhere in the south-
19
western region of the United States.
Boron is a known constituent of coals.
Abernethy and
Gibsonl report that selected coals of the United States
averaged more than 0.1 percent of boron in the ash examined.
Values of boron concentration in coal ash measured 0.005 to
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10
0.65 percent in the Northern Great Plains, 0.008 to 0.096
percent in West Virginia, and 0.21 percent in North Dakota.
Boron contents in the basic coal were determined to be 116
ppm for the Great Plains, 96 ppm for the Eastern Interior,
and 25 ppm for the Appalachian regions of the United States.
No information was found on the emissions to the atmosphere
resulting from these concentrations.
3.2
Production Sources
Although elemental boron does not occur in nature,
it can be produced--usually in the laboratory--by three gen-
eral techniques:
(1) chemical reduction with active elements,
(2) electrolytic reduction, and (3) thermal decomposition.
The most common method for producing large amounts of elemen-
tal boron is the exothermic reduction of boron trioxide with
magnesium.
The product of this reaction, known as "Moissan's
boron," is relatively impure amorphous boron, which usually
is refined by various leaching processes.
Few applications of elemental boron are presently
known.
It is most commonly used in the metallurgical field,
as a deoxidizer and degassifier; as a p-type doping agent for
silicon or germanium semiconductors; and in certain nuclear
applications involving thin films of elemental boron for
neutron counters.
It is considered to have definite potential
as a heat-and oxidation-resistant raw material for space-age
electronic and optical devices.
Crystalline boron, in large samples, is relatively
nonreactive; however, powdered boron reacts readily and
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11
sometimes violently with certain chemical agents--most
violently with oxidizing agents--in some cases igniting or
exploding.
Use of boron minerals and compounds has shown a steady
increase in recent years. Figures from the Minerals Yearbook for
26
1966 reveal the following trends:
Sold or used by
producers 1956-60 1961 1962 1963 1964 1965 1966
Gross weight (tons} 575 603 647 700 776 807 866
Value $40,573 46,936 49,336 54,981 60,871 64,180 68,209
The distribution of boron compounds used in various
industries in 1965 was approximately as follows:
Heat-resistant glass, glass wool, and fiberglass
Soaps and cleaners
Porcelain enamels
Synthetic fertilizers and herbicides
Miscellaneous (leather tanning, metallurgy,
corrosion control, nuclear shielding,
flameproofing; etc.)
32%
16%
13%
8%
31%
The principal producers of boron minerals and compounds
in the United States are:
U.S. Borax and Chemical Corporation
American Potash and Chemical Corporation
Stauffer Chemical Company
Kern County Land Company
3.3
Product Sources
The compounds of boron are normally divided into six
general groups:
(1) boron oxides, boric acid, and borates,
(2) boric acid esters,
(3) refractory boron compounds,
(4}
boron halides,
(5) boron hydrides, and (6) organic boron
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12
compounds.
Within each grouping there exist a large number
of individual compounds, some of pronounced commercial impor-
tance, and others primarily significant to the problem of air
pollution.
3.3.1
Boron Oxide, Boric Acid, and Borates
These compounds consist of several compounds having
very definite commercial importance, used in over 100 differ-
ent industrieso
Borax and boric acid are the most important
of these compounds, with many other compounds--mainly in the
borates--having lesser importance.
Boron dusts of unknown composition are emitted to the
atmosphere by the iron industry.
Analysis of two samples
taken from a baghouse serving a gray iron furnace in the Los
Angeles area revealed concentrations of 0.050 percent and
3
0.054 percent (500 and 540 ~g/g} of boron in the total samples.
3.3.1.1
Boric Acid
Boric acid (H3B03) is usually manufactured by adding
sulfuric or hydrochloric acid to granulated borax or coleman-
ite.
The resulting solution is then cooled to the proper
temperature, and boric acid crystals are removed by filtration.
The American Potash and Chemical Corporation also extracts
boric acid by recovery from plant-end liquors and lake brine
at Searles Lake, Trona, Calif.
Boric acid has a wide variety of industrial uses.
It
is used in glazing in the ceramics industry, as raw material
in making chemicals such as boron trifluoride and boron
carbide, and in making boron alloys that are used in hardening
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13
steel.
Boric acid is used as a nonirritating, mildly antisep-
tic pharmaceutical solution, and for years has been a common
household preparation for washing the eyes.
It is also used
in cosmetics, dye stabilizers, latex paints, solutions for
electroplating~ and flameproofing; in photography; and for
other purposes.
3.3.1.2
Borax
Borax (Na2B407-10H20), commercially the most important
of the borates, is manufactured by crushing borate ore and
dissolving the borax, then removing the insoluble rock and
dry particles through successive solutions and separator
screens.
It is also produced by an evaporation process, using
the borax brine recovered from Searles Lake.
Borax has wide and varied applications in industry.
It
is an important ingredient in the manufacture of glasses and
ceramics;
its mild alkaline and preservative properties are
important to the leather-tanning industry; it is extensively
used as a detergent or in combinations with soap; and it is
frequently used in cosmetics that require a mild alkaline
base.
When combined with boric acid or used separately in
solution, borax is an effective fire retardant and preserva-
tive for wood and wood products.
A significant use of borax
is its application as an additive to prevent the growth of
microorganisms in such petroleum fuels as gasoline, diesel
and aircraft turbine fuels, home heating oil, and other fuels
and solvents.19
In agriculture, borax is an essential component of
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14
many artificial fertilizers.
Most soils that have been
under cultivation for long periods of time become deficient
in elemental boron, which is vital to the health of many
commercial crops.
However, care must be used in the addition
of borax, for when used in large amounts, it then acts as a
nonselective herbicide.
3.3.1.3
Other Borates
Other borate compounds include sodium tetraborate
pentahydrate, used in antifreeze solutions as a rust inhibitor,
in liquid starches, and in the manufacture of other borates;
kernite, one of the most important of borate ores, found
with borax in the Kramer deposits; anhydrous borax, made by
dehydrating and fusing borax, and used chiefly as the source
of sodium borate in high-quality glasses and glazes;
ammonium
pentaborate, used as a component of electrolytes and of fire-
retardant preparations; and many other similar compounds.
3.3.2
Boric Acid Esters
Esterification of boric acid with alcohols or phenol,
or of boric oxide with alcohols results in a wide family of
compounds with special characteristics.
These compounds are
suitable for use as additives to fuels and lubricants, as
antiknock agents in gasoline,
as
inhibitors of growth of
microorganisms in diesel and aviation fuels, as additives
to kerosene jet fuel to prevent icing, and as an oxidation
preventive.
Various compounds are effective as curing
agents for epoxy resins.
Various esters have been used in
nuclear-shielding materials and as ingredients in
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15
nuclear-detecting devices.
In general, therefore, the esters of boron have limited,
specialized uses, the most significant of which are their uses
as fuel additives for automobile power sources.
3.3.3
Refractorv Boron Compounds
Metal borides, boron carbide, and boron nitride
comprise this group of boron compounds.
Metal borides,
formed usually by direct interaction of metallic boron with
other metals, are metallic substances with high electrical
conductivities, high melting points, extreme hardness,
relatively low coefficients of expansion, and high degrees
of chemical stability.
These compounds are used primarily
as structural parts of rocket engines, jet turbines, and
other equipment subjected to high temperatures and chemically
reactive agents.
Boron carbide, produced by the reduction of
boric oxide by carbon at high temperatures, possesses great
hardness and electrical conductivity, and is used as an
abrasive, in jet engine parts, and as a semiconductor.
Boron
nitride, prepared by heating boric oxide with sodium,
potassium, or calcium cyanide, is used in the manufacture of
crucibles and other heat-resistant items and for high-voltage
electrical insulation.
3.3.4
Boron Halides
Boron halides include boron trichloride, boron tri-
bromide, boron triiodide, and sub-halides of boron.
The use
of these compounds is limited almost exclusively to chemical
manufacturing and metallurgy.
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16
3.3.5
Boron Hydrides
Boron hydrides, or boranes, consist of a large group
of boron compounds of growing importance and of definite
significance to a study of air pollution.
Of these, the
most important are considered to be diborane (gas), penta-
borane (liquid), tetraborane (liquid which boils at lSoC),
and decaborane (solid).
3.3.5.1
Diborane (B2Hs)
Diborane is manufactured by the reaction of sodium
borohydride with boron fluoride, using dimethyl ether or
diethylene glycol as a solvent.
Gaseous boron fluoride is
passed into a solution of sodium borohydride, and the evolved
diborane is fractionated from the solvent.
To avoid thermal
o
decomposition, the temperature is kept at 35 C or less.
Diborane is a colorless, poisonous gas, normally stable but
explosively ignitable at room temperatures in air containing
traces of other boranes or moisture.
The major use of
diborane has been its conversion to higher boranes and their
derivatives, which are used as high-energy fuels and pro-
pellants.
Diborane is also used in the manufacture of amine
complexes and as a catalyst in polymerization.
3.3.5.2
Tetraborane (B4H10)
Tetraborane is normally produced by the pyrolysis of
diborane.
It is a colorless, poisonous gas which decomposes
slowly at room temperature and rapidly at higher temperatures.
In the presence of impurities and in moist air it ignites
-------
17
explosively.
No use can be identified in the literature for
this compound.
3.3.5.3
Pentaborane
(Bs Hg )
Pentaborane is a colorless liquid with strong toxic
properties.
When stored for long periods at room tempera-
tures, pentaborane is very stable and does not decompose.
However, in the presence of impurities and in moist air,
pentaborane vapors explode spontaneously.
Anderton6 notes
that it is the best of the synthetic fuels for jet aviation
motors,
and is probably the fuel that will be used for turbo-
jet and ramjet motors in the near future.
20
Kracknell
con-
sidered it to be 1.6 times better than kerosene with respect
to weight calorific power.
32
Analyses of exhaust-gas samples indicated
no appre-
ciable hazard from any of the exhaust-gas constituents; and
although boron or boron compounds are produced as a result
of combustion of the boranes, they have not been identified
or quantitatively evaluated, as have other constituents.
3.3.5.4
Decaborane (B10H14}
Decaborane is a solid, and is toxic.
It is the most
stable borane, does not react with oxygen of the air at room
temperature, and can be worked with in air.
At temperatures
o .
of 100 C, decaborane vapors explode spontaneously.
This com-
pound is used in the vulcanization of rubber, but its most
significant use is as a fuel for rockets and other propellants.
-------
18
3.4
Environmental Air Concentrations
Neither quantitative nor qualitative data have been
found in the literature on the concentration, distribution,
or variation of boron or boron compounds in the atmosphere.
-------
4.
19
ABATEMENT
Little evidence can be found to indicate that action
is being taken to reduce air pollution by boron, except in
the areas involving use of the high-energy fuels.
And even
in these specific areas, the efforts to date have been
largely concerned with preventing accidental spilling of the
fuels.
-------
20
5.
ECONOMICS
No information has been found on the economlC costs
of boron air pollution, or on the costs of its abatement.
Data on the production and consumption of boron are
presented in Section 3.
-------
21
6.
METHODS OF ANALYSIS
Several devices for detecting pentaborane
in air are
available, but they are nonspecific (i.e., they detect other
compounds with similar chemical properties).
A coulometric
8 .
borane monitor was developed by Braman et ale WhlCh was
based on the oxidation of boranes with electrolytically
generated iodine.
This instrument, with a sensitivity of
approximately ~0.02 ppm (40 ~g/m3) pentaborane in
air,
unfortunately was susceptible to overloading when exceSSlve
concentrations of electroactive materials present in the air
desensitized it.
A boron hydride monitor that converted hydrides to
boric acid by pyrolysis and then determined the presence of
boric acid by colorimetry was described by Fristom, Bennett,
11
and Berl.
However, this monitor was not automated.
Kuhns
Forsythe, and Masi21 have outlined a hand-held device for
automatic detection of boron hydrides in air, based on the
reduction of boron hydrides with triphenyltetrazoleum
chloride.
These devices provided sensitivity in the 0.1 ppm
range, but were not continuous monitors and were subject to
interference from all oxidizing or reducing material in air.
Hill and Johnston15 reported on ultraviolet spectro-
photometric detection of decaborane, but this method proved
unsuitable for use with other boranes.
9 7
Braman and Gordon and Braman reported on a direct-
reading, automatic, temperature-insensitive instrument
-------
22
capable of detection of pentaborane down to concentrations
of 0.05 ppm (100 ~g/m3}.
This device used the flame-emission
principle of detection:
in the presence of boranes, a small
hydrogen flame takes on a greenish cast, the intensity of
which is proportional to the borane concentration.
This
device can be operated continuously over an 8-hour period
using a self-contained hydrogen supply and storage batteries.
Development of an atmospheric monitoring device to
detect and record several toxic components,
including
pentaborane, is reported by the Mine Safety Appliances
25
Company.
This device also features pyrolysis to form
boric oxide from borane, followed by detection of the boron
by using n-amylamine reagent.
The company claims a detecta-
bility of 0.01 ppm (20 ~g/m3), with rapid response and con-
tinuous operation.
In a comprehensive 1964 review of analytical methods
27
for determining the presence of boron, Nemodruk and Karalova
listed the following methods.
Photometric methods are widely
used, and are especially suitable for determining mlcro
amounts--at concentrations of 0.05-0.20 ~g, these methods
produce 90% or better accuracies.
Coulometric titration
is said to provide determination of amounts as low as 0.2 ~g.
Spectral analysis is one of the most widely used methods in
metallurgy, capable of determining 5 x 10-5 percent concen-
trations of boron.
Fluorimetric analysis is also used, with
sensitivity to 0.1 ~g of boron.
And radioactive methods are
also available, based on the ability of boron's nuclei to
-------
23
absorb thermal neutrons--this method is considered simple,
and highly efficient, is capable of providing 100 determina-
tions in 8 hours, and has sensitivity to 0.1 ug.
-------
24
7.
SUMMARY AND CONCLUSIONS
Boron compounds,
in general, are toxic to humans and
animals when ingested.
Most boron compounds are moderately
toxic by inhalation, while certain compounds, such as the
high-energy borane fuels, are highly toxic when inhaled.
Dusts of some boron compounds are considered merely nuisance
dusts: others, such as dusts of boric acid and boron oxide,
are moderately toxic.
Borane poisoning in animals has produced listlessness,
incoordination, convulsions, coma,
and death.
Similar symp-
toms have been observed in humans exposed to the boranes,
although none have died.
The incidence of acute borane
intoxication in humans has been low, and adequate data on
exposure, concentrations, and reactions are lacking.
Environmental problems concerning boron and its com-
pounds are generally limited to the particular areas where
the production of boron compounds emits dust particles to
the atmosphere.
However, the highly toxic nature of the
borane fuels poses a constant threat of environmental pollu-
tion wherever they are produced, stored, or used.
Recognition
of this hazard has resulted in strict safety measures which
have minimized accidental exposures.
The use of boron additives in petroleum fuels and
the presence of boron in coals, possibly contribute quanti-
ties of boron to the atmosphere, but no assessment has been
made of the amount of these contributions or of their impact
-------
25
as air pollutants.
Data are not available on the concentration of boron
or its compounds in the atmosphere.
This absence of recorded
data indicating qualitatively or quantitatively the presence
of boron compounds suggests that their presence in the atmo-
sphere may not be fully understood, and the exact nature of
boron as an air pollutant may not be fully appreciated.
Environmental monitoring of boron concentrations should be
considered, particularly near industrial plants engaged in
boron production or use and near borane fuel sites.
Normal entrapment and precipitation procedures applica-
ble to most particulate pollutants should be effective in
controlling or reducing the amount of boron compound dusts
emitted into the atmosphere.
No specific methods for abate-
ment of atmospheric borane compounds have been identified,
but strict regulatory practices are used to prevent accidental
emissions.
No information has been found on the economic
costs of boron air pollution or on the costs of its abatement.
Methods of analysis are available, but these are not
sufficiently sensitive or selective for determining atmospheric
concentrations of boron and its compounds.
Based on the material presented in this report,
further studies in the following areas are suggested:
(1) Determination of ambient air concentrations of
boron compounds, with special emphasis upon localities pro-
ducing or using the boron hydride fuels.
This will involve
-------
26
the development of better methods of analysis for boron and
its compounds than are currently available.
(2) Expansion of research on the characterization and
analysis of exhausts from motor vehicles--to include boron
along with other fuel additives.
-------
27
REFERENCES
4.
9.
10.
11.
12.
13.
1.
Abernethy, R. F., and F. H. Gibson, Rare Elements in
Coals, U.S. Dept. of Interior, Bureau of Mines Infor-
mation Circular IC 8163 (1963).
2.
Adams, R. W. (Ed.), Boron, Metallo-boron Compounds &
Boranes, (New York: Wiley, 1964).
3.
Air Pollution Engineering Manual, U.S. Dept. of Health,
Education, and Welfare, Public Health Service,
Cincinnati, Ohio (1967).
Air Quality Data from the Natural Air Supply Networks,
U.S. Dept. of Health, Education, and Welfare, Public
Health Service, (1966).
5.
American Conference of Governmental Industrial Hygie-
nists, Cincinnati, Ohio (1963).
6.
65 (1956).
Anderton, D., Aviation Week
7.
Braman, R. S., Research and Development of an Auto-
matic Beryllium and Boron Monitor, Armour Research
Foundation of Illinois, Institute of Technology Report
ARF3203-3 (1962).
8.
Braman, R. S., D. D. DeFord, T. N. Johnson, and
L. J. Kuhn, A Coulometric Borane Monitor, Anal. Chern.
32 (Sept. 1960).
Braman, R. S., and E. S. Gordon, The Design of a Port-
able Instrument for the Detection of Atmospheric
Pentaborane and Other Toxic Gases, Institute of
Electrical & Electronic Engineers, Trans. Instrumentation
and Measurement, volume IM-14 (1965).
Brenchley, W. E., The Essential Nature of Certain Minor
Elements for Plant Nutrition II, Botan. Rev. 13 (4)
(April 1947).
Fristom, G. R., L. Bennett, and W. G. Berl, Integrating
Monitor for Detecting Low Concentration of Gaseous
Boron Hydrides in Air, Anal. Chern. 31 (October 1959).
Gould, R. F. (Ed.), "Borax to Boranes," in Advances in
Chemistry Series, American Chemical Society, Washington,
D.C. (1961).
Handbook of Toxicoloqy, National Academy of Sciences,
Washington, D.C. (1959).
-------
28
REFERENCES
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
Hein, G. M., and A. R. Orban, Scrubbing of Fume from
Combustion Gases at Efficiencies up to 99.98 percent,
J. Air Pollution Control Assoc. (May 1961).
Hill, W. H., and M. S. Johnston, Anal. Chern. 27 (1955).
Hyatt, E. C., and M. F. Milligan, Experiences with
Unusual Materials and Operations, Am. Ind. Hyq. Assoc. Quart.
14 (No.4, 1953).
Hygienic Guide Series: Diborane and Pentaborane,
Am. Ind. Hyq. Assoc. J. 19 (No.5, 1958).
Hygienic Guide Series: Pentaborane-9. Am. Ind. Hyq.
Assoc. J. 27 (No.3, 1966).
Kirk-Othmer Encyclopedia of Chemical Technoloqy
(New York: Wiley, 1964).
Kracknell, I. R., Fliqht 71 (1957).
Kuhns, L. J., R. H. Forsythe, and J. F. Masi, Boron
Hydride Monitoring Devices, Anal. Chern. 28 (Nov. 1956).
Lipscomb, W. N., Boron Hydrides, (New York:
1963).
Benjamin,
Manufacturing Chemists Association, Inc., Chemical
Safety Data Sheet SD-84, Boron Hydrides, Washington,
D.C. (1961).
The Merck Index, 8th ed. (Rahway, N.J.:
Merck, 1968).
Mine Safety Appliances Company, Final Report, Development
of an Atmospheric Monitoring System (1961).
Minerals Yearbook, 1966, Bureau of Mines, U.S. Govern-
ment Printing Office, Washington, D.C. (1967).
Nemodruk, A. A., and Karalova, Z. K. Analytical Chemi~try
of Boron, Aoademy of Sciences of the U.S.S.R. (Jerusalem:
Silvan Press, 1964).
Owen, E. C., J. Dairy Res. 13 (1944).
Rozendaal, H. M., A.M.A. Arch. Ind. Hyq. Occupational
Med. 4 (1951).
-------
29
REFERENCES
30.
31.
32.
33.
Samsonov, G. V., L. Ya. Markovski, A. F. Zhigach, and
M. G. Valyashko, Boron and Its Compounds and Alloys,
Academy of Sciences of the Ukranian S.S.R., Kiev, 1960
(Translated by USAEC Division of Technical Information).
Sax, H. I., Danqerous Properties of Industrial Materials,
3rd ed. (New York: Reinhold, 1968).
Thomas, A. A., Aerospace Toxicology Research, NATO AGARD
Conference Proceedings, #2 (Sept. 1965).
Vertan, E., Zentr. Chir. 56 (1929).
-------
30
APPENDIX
-------
APPENDIX
TABLE 1
31
7
PROBABLE RESULTS OF SINGLE EXPOSURE TO PENTABORANE VAPORS
Exposure Time
(min)
Concentration in Air
(ppm) (w.q/m3)
5
15
30
60
5
15
30
60
5
15
30
60
5
15
30
60
390
130
65
30
200
65
30
15
100
30
15
8
25
8
4
2
780,000
260,000
130,000
60,000
400,000
130,000
60,000
30,000
200,000
60,000
30,000
16,000
50,000
16,000
8,000
4,000
Expected Effects in Humans
Convulsions, death
Convulsions
Some decrement in
performance and slight
siqns of toxicity
Emergency exposure limits;
some temporary impairment
of iudqment
-------
32
APPENDIX
TABLE 2
2
ACUTE ORAL AND PARENTERAL TOXICITY OF BORANES
LDs,>
Compound Species Sex a
Route (Wq/q ) Remarks
Pentaborane Rat Intraperitoneal 11,100 Mineral oil
b solution
Decaborane Mouse M Intraperitoneal 33,200
(30,500-36,200)
M Oral 40,900
(33,400-50,200)
Rat M Intraperitoneal 23,400
(21,400-25,600)
M Oral 64,300
(57,500-71,800)
M Percutaneous 740,000 Decaborane-
(67,600-80,900) dioxane - 3
in 1 oil
mixture
Rabbit M Percutaneous 71,000 II
(32,000-155,000)
Dog F Intraperitoneal Up to 25,000 3 of 3 died
with in 3 da
Boron Rat Oral 240,000
hydride Guinea pig Percutaneous >3,200,000
fuel HEF-2 Rabbit Intravenous 7,000
Percutaneous 1,000,000-3,200,000
lIEF - 3; Rat Intravenous 13,000
Hi-Cal 3 Intraperitoneal 20,000-71,000
Oral 40,000
Percutaneous 317,000-502,000
Guinea pig Intraperitoneal 18,000-40,000
Percutaneous 160,000
158,000-251,000
Rabb it Intravenous 4,000-6,000
6,000
Percutaneous 80,000
57,000-105,000
Cat Percutaneous 126,000
(continued
-------
33
APPENDIX
TABLE 2, (Continued)
2
ACUTE ORAL AND PARENTERAL TOXICITY OF BORANES
LD50
Compound Species Sex Route (f-lq/qa) Remarks
Dimethyl-
amine-
borane c Rat
M Intraperitoneal 50,500
(45,900-55,600)
F 39,000
(32,500-46,800)
M Oral 59,200
(52,900-66,300)
Guinea pig M Intraperitoneal 55,900
(34,900-89,500)
Rabbit M Intraperitoneal 35,100
(21,900-56,100)
Trimethyl- Rat M Intraperitoneal 176,000 Dioxane soln
amlne- (159,000-193,000) d il uted wi tll
borane water
pyridine- Rat M Intraperitoneal 73,600 No range
d calculable
borane
M Oral 95,400
(85,200-107,000)
Rat F Intraperitoneal 64,800
(58,900-71,300)
Guinea pig M Intraperitoneal 54,000 No range
calculable
M Percutaneous 220,000 No range
calculable
Triethyl- Rat M Intraperitoneal 22,700 12.4% soln
borane (14,700-35,200) in Nujol
Oral 235,000
(214,000-258,000) 8.9"/0 soln
in Nujol
a95% Confidence limits are shown in parentheses.
bAgar-saline suspensions, except as noted.
c d .
Dissolve ln physiological saline.
dDissolved in propylene glycol.
-------
34
TABLE 3
2
ACUTE INHALATION TOXICITY OF BORANES
Exposure Observation
LC50 period period
Compound Species Sex a ~q/m3 (hours) (d ays )
ppm
Diborane Mouse F 29 33,000 4 14
Mb (27-32)
Rat 40 45,000 4 14
(35-45)
MC 80 91,000 4 14
(73-93)
Dimethyl-
amine-
diborane Mouse M 63 182,000 4 14
(55-123)
Rat M 86 248,000 4 14
(77-99)
Pentaborane Mouse F 3.4 8, 7 00 4 14
M 10.9 28,000 2 2 hr
(10.5-
11.3)
Rat M 6.0 15,000 4 14
M 17.8 46,000 2 2 hr
Decaborane Mouse M 25.7 122,000 4 2
(22.8-
28.0)
Rat M 46 230,0110 4 14
M >95.2d >475, OOOd 4 14
Boron
hydride fuel
HEF-2 Mouse 11 4
Rat 12 4
HEF-3:
Hi-Cal 3 Mouse 6 4
Rat 23 4
Triethyl-
borane Rat M 700 2,800,000 4 7
(667-735) (2,670,000-
2,940,000)
a95% Confidence limits are shown in parentheses.
bAnimals 2 months old-
CAnimals 5 months old.
centration.
-------
APPENDIX
TABLE 4
35
2
ACUTE ORA.L AND PAREN'rERAL TOXICITY OF BORIC ACID
Species
Mouse
Rat
Guinea pig
R:3.bbi t
Do9
Route
Oral
Subcutaneous
Interperitoneal
Intravenous
Oral
Subcutaneous
Intraperitoneal
Intravenous
Subcutaneous
Oral
Intravenous
Oral
Subcutaneous
Intravenous
Dosage
q/kq*
>4.1
3.45 + 0.16
2.07 :t 0.17
1.74 + 0.13
0.8
1.78 ~ 0.12
2.11
2.42
1.52
1.24
5.14
-I
2.66 - 0.22
1.4
0.8
:t
1.33 0.11
+
1.20 0.03
4.0
0.9
0.8
>1.0
2.0
1.0
0.4
LDso
L2thal
4 of 5
1 of 5
LDso
3 of 6 died
2 of 4 died
No observed
LDso
LDso
LDso
LDso
4 or
LDso
LD50
LDBO
LDso
LDso
LDso
LDso
LDs 0
5 of
LDso
Remark s
saln adjusted to
pH 7.4 with NaOH
5 survived 2 wk
injected as 2 cc of
5% soln/min
saln adjusted to
pH 6.9 with NaOH
soln adjusted to
pH 7. 4 wi th N aOH
soln adjusted to
pH 8.8 with NaOH
soln adjusted to
pH 9.4 with NaOH
93% confidence
limits 4.74-5.58
5 survived 2 wk
injected as 2 cc of
5% soln/min
dose
died
died
within 43 hr
effect
*Value following LDBo is standard error.
-------
36
APPENDIX
TABLE 5
2
ACUTE ORAL AND INTRAVENOUS TOXICITY OF SODIUM BORATES
Dosage
Compound Species Route (q/kq) Remarks
Borax Mouse Oral 2.0-3.0 LDso
Intravenous 1.32 LDso injected In
1 sec
Guinea pig Oral 5.33 LDso
Sodium per- Rat Oral 0.65 No deaths
borate mono- Rabbit Intravenous 0.078 LDs Ij 2% soln over
hydrate 5 min period
Cat Intravenous 0.6-0.9 LDslj anesthetized
animals. 3% soln
injected at
1 cc/min
Sodium Rabbit Intravenous 0.3 No toxic effects
metaborate noted
-------
APPENDIX
TABLE 6
37
2
ACUTE ORAL TOXICITY AND EYE IRRITATION OF BORATE ESTERS
:ornpound
rriethyl borate
rri-n-propyl borate
rriisopropyl borate
rri-n-butyl borate
rriisobutyl borate
rri-sec-butyl borate
rri(methylisobutylcarbonyl)
borate
rri-n-amyl borate
rri-n-hexyl borate
rri-n-octyl borate
rri(2-octyl} borate
rri(2-ethylhexyl) borate
rri-n-dodecyl borate
rrioleyl borate
rrihexylene-glycol biborate
rri-o-cresyl borate
rri-o-chlorophenyl borate
rristeraryl borate
rri(2-cyclohexylcyc1ohexyl)
borate
rri(2-p~enylcyclohexyl)
borate
rrietnano1amine borate
rrioctyleneglyco1 borate
rriphenyl borate
rriphenylcyclohexyl borate
rri(diisobutylcarbonyl)
borate
rriisopropanolamine borate
L 95 0 ,
ml/kg
(mouse)
2.1
2.08
2.5
2.15
2.4
2.1
1.6
1.24
2.13
1.29
3.3
3.3
1.66
6.2
1.72
0.40
<0 . 23
6.2c
2.0Sc
3.4c
6.2c
5.lc
0.2c
1.24c
3.7c
7.2c
Vehiclea
a-=Iueous suspension
aqueous suspension
a-=Iueous suspension
15% aqueous soln
l~/o olive-oil solnd
5% aqueous solnd
5% olive-oil sOln~
l~/o Qlive-oil soln
l~/o aqueous soln
Eye
. . . b
lrrltatlon
(rabbit)
mild
mild
mild
mojerate
mild
mild
severe
moderate
moderate
moderate
mild
mild
moderate
mild
moderate
corneal scars
corneal scars
mild
moderate
mild
mild
corneal
severe
moderate
scars
mild
~UDdiluted liquid administered except
See text for grading of injury.
~g/kg.
Solution warmed to 40oC.
as notej.
-------
,PPENDIX
TABLE 7
38
2
ACUTE TOXICITY OF ORGA-T\JOBORON COMPOUNDS
;ompo'.md
~rimethyl
borate
~rimeth-
oxyboroxin
)imethylphos-
p~ino borane
trimer
!enzene-
boronic acid
I-Amino -4-
carboxyben-
zeneboronic
acid
)- ( 2-Carboxy-
2-acetamido-
ethyl)-benzene-
boronic acid
Species
Mouse
Rat
Rabbit
Rat
Rat
Rabbit
MO'.lse
Rat
Guinea
pig
Rabbit
Dog
Mouse
Cat
Mouse
Route
Oral
Intraperitoneal
Oral
Intraperitoneal
Intraperiton2al
Percutaneous
Oral
Oral
Oral
Percu taneo i.1S
Intraperitoneal
Oral
Intraperitoneal
Oral
Percutaneous
Intravenous
Intraven:Jus
Intravenous or
intracarotid
Intravenous
Dosage
(q/kq)
1.29a
LOa
7.91
6.14
2.8a
1.6-3.2a
1.6-3.2a
1.98
5.16
0.0135
0.04-0.05
0.06-0.8
0.56
0.74
0.284
0.60-0.65
4.5-5.0
0.45
3.29
2.06
0.66
5.72
------
Re;n3.rks
LDs 0
Approx lethal dose
LDs 0
LDso 95% confidence
limit 4.97-7.95
Approx lethal d:Jse
II II II
II
II
II
LDso 95% confidence
limit 1.47-2.68
LDso
LDs 0 1% corn-oil
soln
MLDb 1% corn-oil
soln
MLDP 10% corn-oil
soln
Lethal dose
LDso 2010 corn-oil
suspension
Lethal dose
MLDb 25% corn-oil
sgspension
MLD oily paste
Lethal dose
LD50 soln adjusted
to pH 8.1
LDso soln adjusted
to pH 9.5
Tolerated
LDso soln adjusted
to pH 7. 5
(continu2d)
-------
APPENDIX
39
TABLE 7 (Continued)
ACUTE TOXICITY OF ORGANOBORON COMPOUNDS2
Dosage
Compounds Species Route (q/kq) Remarks
m-Carboxyben -
zeneboronic
acid Mouse Intravenous 2.56 LDso soln adjusted
to pH 7.4
p-Carboxyben -
zeneboron ic
acid Mouse Intravenous 1. 74 LDso soln adjusted
to pH 9.4
m-Ureido-
benzene-
boronic acid Mouse Intravenous 1.02 LDso soln adjusted
to pH 10.0
2-Acetamido-
benzene-l,4-
diboronic
acid Mouse Intravenous 2.54 LDso soln adjusted
to pH 10.6
2-Nitrobenzene-
1, 4-diboronic
acid Mouse Intravenous 1.68 LDso soln adjusted
to pH 9.3
p-Borono-
phenylalanine Mouse Intravenous 1.52 LDsn soln adjusted
to pH 10.0
m-Borono-
succinanilic
acid Mouse Intravenous 4.09 LDs0 soln adjusted
to pH 7.4
Cat Intracarotid 0.86 Tolerated
B,B',B"-
Triallyl-N,N',
N"-triphenyl
borazine Mouse Intraperitoneal 2.50 3 of 5 animals died
1.25 5 of 5 animals
survived
(continued)
-------
APPENDIX
40
TABLE 7 (Continued)
2
ACUTE TOXICITY OF ORGANOBORON COMPOUNDS
Compound
2,6-Di-tert-
butyl-4-
methylphenyl
diisopropyl
borate
Nonyl boric
acid
Dodecyl boric
acid
Species
Dosage
(q/kq)
Remarks
Route
Rat Oral 5.2 LDsn death in 2-5
days
Rabbit Oral 7.0-8.0 MLDb death in 24-48
hr
Percutaneous 10 2 of 2 survived 10
days
Rabbit Percutaneous 0.82 2 of 3 animals died
Rabbit Percutaneous 1. 75 All 3 animals
survived
amI/kg.
bMinimum lethal dose.
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41
APPENDIX
TABLE 8
AC:UTE INI-fALATION TOXICITY OF BOR,)N HALIDES2
~ompound
Species
Air
Concentration
(ppm)
750
750
750
Exposure
Period
(hours)
Mortality
~ron trifluoride
Mouse
Rat
Guinea pig
5.5
5.5
5.5
1/10
1/10
10/10
~ron trifluoride-
dimethyl ether
pig
225
485
50
20
20
85
50
100
50
100
14a
14a
3.8
7
7
14a
14a
14a
14a
14a
1/4
1/2
10/10
10/10
0/10
0/10
0/15
0/10
10/10
~ron trichloridec
Mouse
Rat
Guinea
Mouse
Rat
Guinea
Mouse
Rat
Guinea
pig
~ron trichlorideb
pig
a
Two 7-hour daily exposures.
b
Cages used continuously for 7 hours.
c
Clean cages substituted every 2 hours.
-------
APPENDIX
42
TABLE 9
ACUTE ORAL AND PARENTERi\L TOXICITY OF
MISCELLANEOUS BORON COMPOUNDS2
Dosage
Compound Species Ro ute (~.q /kq*) Remarks
Sc>di urn Mouse Intraperitoneal <18,000 Approx lethal
borohydride dose
Rat Intraperitoneal 18,080 Approx lethal
dose
Oral 160,000 2 of 5 a'1.imals
died
Rabbit Intraperitoneal 60,OJO Approx lethal
dose
Potassium
borohydride Rat Oral 160,000 1 of 5 animals
died
Potassium Mouse Intraperitoneal 590,000 LDso
fluoroborate (460,000-
750,000)
Rat Intraperitoneal 240,000 LDso
(130,000-
460,000)
Rabbit Intraperitoneal 380,000 LDso
(190,000-
780,000)
Sodium deca-
hydrodecaborate Mouse Intravenous 1,040,000 LDso
*95% confidence limits are shown ln parentheses.
-------
APPENDIX
Compound
Boric acid
H3B03
Boron
B
TABLE 10
24
PROPERTIES, TOXICITY AND USES OF BORON AND SOME BORON COMPOUNDS
Properties, °c
o
mp 160
mp 21500
Toxicitv
Ingestion or absorption may
cause nausea, vomiting,
diarrhea, abdominal cramps,
erythematous lesions on
skin and mucous membranes,
circulatory collapse,
tachycardia, cyanosis,
delirium, convulsions,
coma. Death has been re-
ported from less than 5
g in infants and from 5
to 20 g in adults. Chronic
use may cause borism (dry
skin, eruptions, gastric
disturbances). Caution:
several cases of fatal
poisoning have occurred
following its absorption
from granulating wounds
and abraded skin areas
The element itself has low
toxicity, but some boron
compounds are moderately or
highly toxic. See indivi-
dual compounds
Uses
For weatherproofing wood and
fireproofing fabrics; as a pre-
servative; in manufacture of
cements, crockery, porcelain,
enamels, glass, borates,
leather, carpets, hats, soaps,
artificial gems; in nickeling
baths, cosmetics, printing and
dyeing, painting, photography;
for impregnating wicks; in
electric condensers; for har-
dening steel. Med. use: mild
topical astringent, antiseptic.
Vet. use: in aqueous solution
for application to wounds,
ulcers, and inflamed mucous
membranes, mouth washes, eye
and skin lotions. Also as hot
fomentations for abscesses and
ulcerative skin conditions.
Also in dusting powders
In nuclear chemistry as neutron
absorber, in ignition recti-
fiers, in alloys, usually to
harden other metals
(continued)
~
w
-------
APPENDIX
TABLE 10 (Continued)
24
PROPERTIES, TOXICITY AND USES OF BORON AND SOME BORON COMPOUNDS
Comoound Properties, °c Toxici tv Uses
Boron monoxide Vaporizes at See Boron
(BO)x 1300-15000 in-
to gaseous
B202
Boron nitride mp 30000 :l'n manufacture of alloys; in
EN semiconductors, nuclear
reactors, lubricants
Boron tribromide mp -450 In manufacture of diborane
I BBr 3 bp 900 I
Boron trichloride bp 12.50 In manufacture and purification
BC13 mp -1070 of boron, as catalyst for
organic reactions, in semicon-
ductors
Boron trifluoride mp -127.10 May be highly irritating To protect molten magnesium I
BF3 bp -1010 to the eyes, mucous mem- and its alloys from oxidation
branes as a flux for soldering mag-
nesium, as a fumigant, in
ionization chambers for the
detection of weak neutrons. By
far the largest application of
boron trifluoride is in cata-
lysis with and without pro-
i I moting ag en t s
~
~
(continued)
-------
APPENDIX
TABLE 10 (Continued)
24
PROPERTIES, TOXICITY AND USES OF BORON AND SOME BORON COMPOUNDS
Compound ProDerties, °c Toxici tv Uses
trifluoride 0
Boron bp 125.70 On decomposition, forms As catalyst in acetylation,
etherate mp -60.4 highly toxic fumes of alkylation, polymerization, de-
( CH 3 CH 2 ) 2" 0 . BF 3 fluorides hydration, and condensation I
reactions
Boron anhydride mp 5770 In metallurgy; in analysis of
(Boron oxide) silicates to determine Si02 and
B203 alkalies; in blowpipe analysis
Diboron 0 Details unknown.
mp -92. 6 Probably
tetrachloride a strong irritant
B2C14
Potassium Decomposes at No specific data. In g en - As reducing agent for aldehydes,
borohydride ~5000 eral, boron hydrides are ketones, and Schiff bases in
KBH4 quite toxic and may cause non-aqueous solvents. Also to
injury to liver, kidneys, reduce acids, esters, acid
central nervous system chlorides, disulfides, nitrilee.
inorganic anions. Further used
to generate diborane, as
foaming agent, as scavenger for
traces of aldehyde, ketones, I
and peroxides in organic I
chemicals
ISOdium borohydridE 36-370 See note for potassium Same above '
mp as I
NaBH4 borohydride
,j:::,
U1
( continued)
-------
APPENDIX
CompotU1d
Sodium borate
(Borax)
Na2B407
Decaborane
B10H14
Diborane
IB2H6
J
I
I
TABLE 10 (Continued)
24
PROPERTIES, TOXICITY AND USES OF BORON AND SOME BORON COMPOUNDS
Properties, °c
o
mp 75
Toxicity
Ingestion of 5 to 10 g
by young children may
cause severe vomiting,
diarrhea, shock, death.
Also see boric acid
o
mp 98.8
bp 2130
Dizziness, nausea, vomi-
ting, muscular tremors,
and evidence of liver
injury have been reported
in man
o
mp -165
o
bp 9 2 . 5
Inhalation may produce
irritation of ltU1gs,
pulmonary edema. High
exposures produce symp-
toms resembling metal
fume fever. See decaborane
Uses
For soldering metals; in manu-
facture of glazes and enamels;
for tanning; in cleaning com-
potU1ds; for artificially aging
wood; as preservative against
wood fungus, either alone or
with other antiseptics; for
fireproofing fabrics and wood,
curing and preserving skins
In rocket propellants, as cata-
lyst in olefin polymerization
As a catalyst for olefin poly-
merization, as rubber vulcani-
zer, as reducing agent, as
flame-speed accelerator, in
rocket propellants, as inter-
mediate in preparation of other
boron hydrides, ln conversion
of olefins to trialkylboranes
and primary alcohols, as a
doping gas
I
(continued)
~
0\
-------
APPENDIX
TABLE 10 (Continued)
24
PROPERTIES, TOXICITY AND USES OF BORON AND SOME BORON COMPOUNDS
Compounds Properties, 0 Toxici tv
C Uses
Procaine borate mp 16S-1660 Side effects: minimal Med. use: local anesthetic
C13H20N 202 systemic toxicity.
Anaphylactic reactions
may occur
Pentaborane mp -46.60 Dizziness, nausea, vomi- In rocket propellants
BSHg bp 480 ting, muscular tremors,
and evidence of liver
injury reported in man
.p:.
-...j
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