BACKGROUND DOCUMENT
RESOURCE CONSERVATION AND RECOVERY ACT
SUBTITLE C - HAZARDOUS WASTE MANAGEMENT
SECTION 3001 - IDENTIFICATION AND LISTING OF
HAZARDOUS WASTE
§261.22 - Characteristic of Corrosivity
MAY 2, 1980
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF SOLID WASTE
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Table of Contents '<-'
>;.2.4401
I. Introduction
II. Proposed Regulations
III. Rationale for the Proposed Regulations
A. Rationale for Proposing a Corrosiveness Characteristic
B. Rationale for Proposing Definition of Corrosiveness
IV. Test Methods
A. pH
B. Metal Corrosion
V. Comments on the Proposed Regulations
VI. Promulgated Regulation
Appendix A - Corrosiveness - State Identfication Criteria
Appendix B - Examples in which Corrosive Wastes Caused Tissue
Damage
Appendix C - Case Histories of Accidents Caused by Mixing
of Incompatable Wastes
Appendix D - Reactions Between Acids or Bases and Other
Substances - Possible Adverse Consequences
Appendix E - Examples of Corrosive Wastes Caus-lng^-Damage
to Aquatic Life
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I. Introduction
Subtitle C of the Solid Waste Disposal Act, as amended by
the Resource Conservation and Recovery £<-t of 1976 creates a
comprehensive "cradle-to-grave" management control system for
the disposal of hazardous waste designed to protect public
health and the environment from the improper disposal of
such waste. Section 3001 of that Subtitle requires EPA to
identify the characteristics of and list hazardous wastes.
Wastes identified or listed as hazardous will be included in
the management control system created by Sections 3002-3006
and 3010. Wastes not identified or listed will be subject to
the requirements for non-hazardous waste imposed by the States
under Subtitle D. The Agency has determined that corrosiveness,
the property that makes a substance capable of dissolving
material with which it comes in contact, is a hazardous
characteristic because improperly managed corrosive wastes
pose a substantial present or potential danger to human health
and the environment. The purpose of this document is to
explain the Agency's definition of corrosive waste, to discuss
the comments received on the Agency's proposed definition of
corrosive waste and to discuss the changes made in response
to those comments.
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II. Proposed Regulation
§250.13(b) Corrosive waste.
(1) Definition - A solid waste is a hazardous waste
if a representative sample of the waste:
(i) Is aqueous and has a pH less than or equal
to 3 or greater than or equal to 12 as determined
by the method cited below or an equivalent method.
(ii) Corrodes steel (SAE 1020) at a rate greater
than 0.250 inch per year at a test temperature of
130°F as determined by the method cited below or an
equivalent method.
(2) Identification method.
(i) pH shall be determined using a pH meter, following
the protocol-specified in the "Manual of Methods for
Chemical Analysis of Water and Wastes" (EPA
625-16-74 003).
(ii) Rate of metal corrosion shall be determined
using the protocol specified in NACE (National
Association of Corrosion Engineers) Standard
TM-01-69.
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Ill. Rationale for the Proposed Regulation
A. Rationale for Proposing a Corrosiveness Characteristic
Corrosiveness was chosen as a characteristic of
hazardous waste because improperly managed corrosive wastes
present a danger to human health and the environment.
Corrosion involves the destruction of both animate and inanimate
surfaces. For regulatory purposes, the Agency believes that
hazards associated with each must be considered. Wastes
capable of destroying animate surfaces may injure human
«
tissue while wastes capable of corroding inanimate surfaces
may destroy containers holding hazardous substances, thereby
enhancing the introduction of contaminants into the environment.
In addition, corrosive wastes can react with other wastes to
generate additional hazardous substances or dangerous amounts of
heat. A number of States identify Corrosiveness as a hazardous
waste property in their hazardous waste regulations. These
State regulations are indexed in Appendix A.
B. Rationale for Proposed Definition of Corrosiveness
1. Introduction
The Agency has chosen pH as one indicator of
Corrosiveness because the hydrogen ion concentration, which
pH measures, is causally related to many of the hazards
associated with Corrosiveness (a thorough discussion of the con-
cept of pH may be found in Reference 1). Application of a character-
istic based on pH encompasses the following hazards:
o Harm to human tissue. Wastes exhibiting very
high or low pH levels may cause harm to transporters
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and other persons coming into contact with the
waste.
o Solubilization of toxic constituents of
solid waste resulting in migration to groundwater.
Unregulated disposal of wastes with very high
or low pH levels may contribute to the solubiliza-
tion and migration of toxic constituents to
groundwater/ thereby threatening the health of
. those who use groundwater as a source of drinking
water.
o Dangerous chemical reactions. Co-disposal of
wastes with high or low pH levels may produce
reactions resulting in dangerous heat production
or generation of toxic fumes.
o Harm to aquatic life. Improper disposal of
wastes exhibiting either high or low pH levels
may alter the pH of surface waters to the
detriment of aquatic organisms.
The Agency has chosen metal corrosion rate as another
expression of corrosiveness because the metal corrosion rate
indicates the ability of a corrosive waste to eat through its
container and escape to the surrounding area where it may .
react with nearby wastes to release hazardous substances
or corrode other containers holding hazardous wastes. Available
information reveals that hazardous wastes are frequently
stored, transported, or disposed in metal containers.
Application of a characteristic based on metal corrosion rate
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encompasses hazards associated with the escape of corrosive
wastes from their containers to the surrounding area.
The various hazards covered by the proposed corrosiveness
characteristic are discussed below in greater detail.
2. Effects of Improper Disposal of Wastes Exhibiting
High or Low pH Values
(a) Injury to Humans
Wastes exhibiting very high or low pH levels may cause
harm to persons who come into contact with the waste. Acids
cause tissue damage by coagulating skin proteins and forming
acid albuminates. Strong bases or alkalis, on the other
hand, exert chemical action by dissolving skin proteins,
combining with cutaneous fats and severely damaging keratin.
Alkali burns tend to be progressive due to the formation of
soluble alkaline proteinates and are therefore more dangerous
than acid burns which may be limited by the insolubility of
acid albuminates. In each type of burn, the hydrogen ion
and hydroxyl ion concentration is a factor related to injury.(2)
Studies indicate that pH extremes above 11.5 and below 2.5
generally are not tolerated by human corneal (eye) tissue (3).
Substances most frequently implicated in damage to human
tissue in occupational settings are sulfuric, hydrochloric,
hydrofluoric, nitric, acetic, carbolic, formic and oxalic
acids and ammonia, caustic soda, and caustic potash (4,5).
EPA files contain descriptions of several incidents in which
contact with corrosive wastes resulted in tissue damage (6).
Three incidents are described in Appendix B.
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(b) Solubilization of Toxic Contaminants
Low or high pH levels significantly promote the solubili—
zation of certain toxic substances such as heavy metals.
Once solubilized, these hazardous substances can migrate to
a groundwater body where, under proper conditions, they can
move great distances without significant attenuation of
i
toxicity. Since approximately half the population of the
United States depends on groundwater as a source of drinking
water, this enhanced migration of toxic constituents warrants
serious concern (7). A study of 50 land disposal sites in
which industrial wastes had been placed revealed that sub-surface
migration of hazardous substances is prevalent. Migration
of toxic heavy metals was confirmed at 30 of the sites? at
26 of the sites levels in excess of EPA drinking water standards
were discovered (8) . Damage resulting from contamination of
groundwater by toxic inorganic substances is well documented.
Reference 6 contains many examples of injury to human "health
and the environment attributable to contaminated groundwater.
The tendency of toxic waste constituents to solubilize
in response to increased or decreased pH levels is illustrated
by the theoretical solubilities of heavy metal compounds in
aqueous solutions at various pH values. For instance,
calculations demonstrate that a drop in pH from 4.0 to 2.0
should increase the solubility of red mercury oxide (HgO)
or of chromium hydroxide (Cr(OH)3) in water approximately
one hundred times (9). In general, compounds of mercury tend
to solubilize in an acidic environment while chromium, cadnium,
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lead and silver compounds may be soluble in either acidic or
alkaline media., Compounds of arsenic and selenium solubilize
more readily in an alkaline environment. (9,10,11)
Because the solubilization of waste stream components is
a complex phenomenon dependent upon factors such as the ionic
strength of the medium, the oxidation potential, and the presence
of complexing and chelating agents and available anions, the
above theoretical solubilities—which are applicable to pure
compounds in simple systems—cannot readily be extrapolated
to complex waste systems. However, these figures clearly
reveal trends in the relationship between pH and solubility.
Thus, although limits which precisely define the low or high
pH values at which solubilization of the various heavy metal
compounds occurs in all wastes cannot be established in reliance
on these figures, in general, there is greater potential for
solubilization as pH values approach the lower and upper ends
of the scale.
(c) Dangerous chemical reactions
Co-disposal of incompatible wastes may lead to the
following harmful reactions: 1. heat generation, 2. fire,
3. explosion, 4. formation of flammable gases, 5. volatili-
zation of toxic or flammable substances, 6. formation of
substances of greater toxicity, 7. formation of compounds
sensitive to shock and friction, 8. pressurization in closed
vessels, 9. formation of toxic fumes, 10. dispersal of
toxic dusts, mists and particles, and 11. violent polymeri-
zation (12). Improper disposal of wastes exhibiting high or
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Intentionally Blank
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low pH levels is often associated with these adverse conse-
quences. Toxic and flammable gases/ for instance, may
be generated when cyanides or sulfides are mixed with acids
(13). Violent chemical reactions can occur when strong acids
are mixed with strong bases. Appendix C contains case
histories documenting damage to human health, the environment
and property caused by mixing acidic or caustic wastes with
other wastes. Appendix D lists possible adverse consequences
resulting from reactions between acids or bases and other
classes of compounds.
It is difficult to establish an exact pH value at which
wastes of varying composition pose a hazard, but certainly
the tendency to cause harmful chemical reactions becomes more
pronounced at the extremes of the pH scale. By any estimation,
highly acidic or highly alkaline liquid wastes have the potential
to cause chemical reactions which can have an adverse effect on
human health and the environment.
(d) Injury to aquatic life
Improper disposal of wastes exhibiting high or low pH
may alter the pH levels of surface waters, resulting in harm
to aquatic life. Studies indicate that the optimum pH range
for freshwater fish is 6.5 - 9.0; an increase or decrease of
2 pH units beyond the optimum causes severe effects. Bioassays
conducted on the fathead minnow revealed that a generation
maintained in environments with pH values of 4.5 and 5.2
were deformed and exhibited abnormal behavior. As Table 1
shows, pH levels of 11.0 or 3.5 are fatal to all species of
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fish. At pH levels below 3 and above 12, very few organisms
are capable of survival (14).
Addition of wastes exhibiting low or high pH levels to
surface waters can also increase the toxicity of substances
in the water. Acidification of the water can result in the
release of free carbon dioxide in toxic quantities, and a
drop of about 1.5 pH units can cause a thousand-fold increase
in the acute toxicity of a metallocyanide complex (14). In
addition, alteration of the surface water pH is capable of
affecting the productivity of food organisms which fish and
wildlife need to survive. Appendix E lists incidents of
damage to aquatic life caused by wastes exhibiting high or
low pH values (6).
(e) EPA' s f ina 1 pH 1 imi't's
As noted above, the Agency has chosen pH as one measure
of corrosiveness because pH provides an easily-measurable,
multi-purpose indicator of several potentially hazardous
conditions. In its proposed regulation, the Agency defined
aqueous wastes with pH levels below 3.0 and above 12.0 as
being hazardous. These limits were chosen in an attempt to
balance the following considerations: sensitive human tissue
may be damaged when contacted with substances exhibiting pH
levels below 2.5 or above 11.5? strongly acidic or basic
conditions significantly enhance the solubilization of toxic
contaminants and are an integral cause of dangerous chemical
reactions; aquatic life is adversely affected where the pH
of the water is below 6.5 or above 9.0 and is virtually
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non-existent in media with pH values below 3.0 and above
12.0.
In response to the proposed pH limits, a great many
comments were received advocating the extension of the
accpetable pH range. A number of commenters argued that the
proposed upper pH limit of 12.0 would include waste lime and
many lime treated wastes and sludges which generally have a
pH between 12.0 and 12.5 and which can be put to agricultural
and other beneficial uses. Many of these commenters suggested
raising the upper pH limit to 12.5 while others suggested
raising the limit to 13.0. A number of commenters argued
that the proposed lower pH limit of 3.0 would include many
common and innocuous substances such as cola drinks which
exhibit pH levels of between 2.0 and 3.0 and many industrial
wastewaters prior to neutralization which also exhibit low
pH levels. Many of these commenters suggested lowering the
pH limit to 2.0; others suggested lowering the limit to 1.5.
Upon consideration of these comments and after further
deliberation, the Agency has decided to extend the range of
acceptable pH levels by decreasing the lower limit from pH
3.0 to 2.0 and increasing the upper limit from pH 12.0 to
12.5. With respect to the upper limit, the Agency agrees
with the coramenters that otherwise non-hazardous lime stabilized
sludges and wastes should not be designated as hazardous.
Accordingly, the Agency has adjusted the upper limit to pH
12.5 to exclude such wastes from the system. Raising the
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TABLE —.1.-—A Summary of Some Effects of pH on
Freshwater Fish and Other Aquatic Organisms 8
KMWiefelS
11.5-1J.J.
11.0-11.5.
^e odfc rlej (Tridiocteri) tOTrt ktrt emerpsa reduced.
Rigid* tetbilU it species ol fob.
1C.MO.S...
1.5-10.8...
J.W.S
LS-S.6
I.M.5
7.M.I....
t. 5-7.0
f.M.J .....
5. 5-t.O .....
i. C-5.5 .....
4.5-5.0
4.M.5
I.S-4.0
J.C-J.5
leratnX i»d pike. UUal to some stonefies (Pletoplen) ind dratonffes (OdorataX ddds
fly emefputa reduced.
. Withstood by almonds for short periods but eventually leUal Eicwds tolerance ef ttwpBS
(Lepomisiucrochinn)indpTo«ibly jcldfisb. Some typial stoAefliesindmiyfiet(£pa*Mn)
sanin witt reduced imervsna.
. Uthii to aliwids orer i orobnpd period ol b'ne ind w viable fishery for coldwitor species.
Reduces popabb'oas ol wirmwitor fish sad mty be hmilol to development stops, tntu
reduced emapflct of some slortef&cs.
. likely to be tarmlol to almonids ind percb (Pera) H present lor I considerable knfth ef tin*
ind w mbk fishery lor coldwiter species. Reduced popibtjpni ol wirmweter Ssb. Can I raid
these lenb.
. Approaches tofcnnce limit ol SOIM almonids, whiteftsh (Ccnfonus), catfish (Icbbridae), ud
perch. Anidrd by pJdfish. No ippirenl eftects on inrerttbntes.
Moblity ol art sperm reduced. Pirb'il mortality ol burbot (Uti loll) en*.
F*ll rah production. No known harmful eflects on idult or immature fish, but 7.0 a nor low Soil
lor Gimnuras reproduction ind perhips for some other cmticeins.
Not kettal to frsh unless hury mttils or cyanides thit irt more tnic it tow pH ire present.
Generally III! fish production, but lor tithead minnow (Pimeprales promebs). frequency el
ssiwnitf ind number ol etp ire somewhat reduced. Inrtrtebnlci eicept mntacnu nbbvtry
Dormil. incrwfinj common ocairrence ol monusU. Micrgorpniims, ilpe. ind fcfber pbits
Unliki ly to be tout to fisb unless fret arbon dioiide is present in emss ol 100 ppm. Good «ujbc
papubtions with nried species an esist with some eucptions. Riprodurtort ol Gimmaras lad
Diphnii primtod, perhips other crustaoins. Agiubc pbnts ind rmooorpniuns rebbrely
normal esctpt lunfi Iregwnl
Eistern brook trout (Silreinus lontinans) surrin it over pH 5i Rtinbow trout (Silno ptrdneri)
do not OBOT. It uturil situiboos, small popubbon ol rebbnh; lew species of fist an be
lound. Growth rate ol carp reduced. Spiwninf ol litheid minnow sitmfianUy reduced. Molfesfc]
rare.
Very restricted tlsh popubbons but not lethal to iny fish species onless CO; ii hifh (orer 25 ppoX
or water eonlairti iron alts. Mfy be Mthil to nil lid brae ol sensitive fish species. Prrmitt
soawn'nt of littiad minnow. Benthic inrerlebrates moderately dinrst, with ceraii btact fta
(SimDEidat).miyflies(Ephemerelli), stonefliM.itdniidps(Chironomidii)presatinaMiben.
UUal to olhet invertebrates such is the mayfly. Bicteriil speciis diversity decrnsed; yeasti
ind snltw ind iron bactorii (Thiobidllui-FinobiBllin) common. Alpe totonibrj dime and
hi(hef pujets wiH pow. ~'~~~ • '
Ho viable fisher; an be maintained. Likely to be leUal to erjs ind fry ol salmonids. A satmmid
popubbon could not reproduce. Hirmlul, bot not Mcnarily lethil to carp. Adut brow* troit
(Salmo trctta) an survive in pell witen. Bentbic fiuiu restricted, mar flits reduced. UUal b
several typial stancftcs. Inhibits emerpme of certain caddil fly, stonefry, and Teidp brne.
Otitonu are dominant ilpe.
Fish popubrb'ons f roiled: only i lew specie! survive. Perth, some coarse fish, and pike on ucf-
nite to this pM. bit only pike reproduce. Lethal to liUtead minnow. Some caddis ties ind dntoa-
fles fcond in such habiUts; certain midps domirarrl Flora restricted.
Uttal to almonids ind bluefllls. IJmil ol tolerance ol punkimeed (Upomis libbosus). perch,
pike, ind some coirse fish. ATI flora ind IIUM severer; restricted in number ol species. Cattiil
(Typha) is only common hif h« plant.
Onikety that i*y tsh cae surrin lor more than I lew noun. A few kinds of irvrrtcbnta such as
certain midps aod alderfies, aid I lew species of arpe nay be lound it this pH raep ard tower
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upper limit to pH 12.5 should not compromise protection of
human health. Although eye tissue is damaged when the pH is
above 11.5, normal skin tissue is clearly less sensitive than
eye tissue. Consequently, increasing the upper pH limit to
12.5 should not significantly increase rhe likelihood of
damage to skin. Also, taking into account the many factors
that might influence heavy metal solubility and causation of
harmful chemical reactions, an increase of 0.5 pH unit is not
expected to significantly compromise protection against these
two h az ard s.
With respect to the lower limit, the Agency is not
necessarily in agreement with the comments that such "innocuous"
substances as cola drinks, if disposed of in a landfill, will
have only benign consequences. Nevertheless, it agrees with
the comments that 2.0 is a better justified lower pH limit
than 3.0. The Agency originally chose 3.0 as its lower limit
based on tissue damage and heavy metal solubilizat ion.
Although studies on corneal tissue deaoastrated that injury
was sustained on contact with substances exhibiting pH levels
below 2.5, the proposed pH limit was set at 3.0 to provide an
extra margin of protection against heavy metal solubilization.
Corneal tissue, however, is more sensitive than skin tissue
so reducing the lower pH limit to 2.0 should still allow
adequate protection against skin injury. Similiarly, lowering
the pH limit to the avowedly highly acidic level of 2.0
ensures that the limit is more likely to encompass those
wastes which tend to solubilize toxic substances and .cause
harmful reactions.
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3. Effects of Improper Disposal of Wastes Capable of
Corroding Metal.
Wastes which have the capacity to corrode metals
can corrode their containers during transportation, storage
or disposal and escape into the surrounding area. If such
corrosive wastes are toxic, their escape can cause direct
injury to persons handling the waste and can contaminate the
environment. If such wastes exhibit lov or high pH, their
escape can result in all the hazards associated with low or
high pH, as discussed above. Wastes capable of corroding
metals can also cause the corrosion of other containers in
which hazardous wastes are stored, resulting in the leakage
of those wastes into the environment. This unplanned leakage
can result in injury to persons handling the wastes and the
contamination of the environment.
Metal corrosion is a complex process; a more detailed
discussion of its mechanisms may be found in Reference 15.
Factors which influence the rate of corrosion include tempera-
ture, the metal(s) involved and aeration, composition and pH
of the corrosive medium.. For example, a corrosive material
with a pH less than 4.0 will cause iron to dissolve rapidly
accompanied by evolution of hydrogen. At pH 4.0-9.5 the
rate of attack is usually low and fairly constant then de-
creases to a minimum at pH 12.0. Increases in pH above 12.0
accelerate dissolution of the metal but the corrosion rate is
generally much less than that occurring under acidic conditions.
In practice, alkaline solutions do not severely damage steel.
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The presence of dissolved salts may also accelerate or inhibit
corrosion; chloride and sulfate ions interfere with development
of protective films and contribute to the breakdown of passive
films already in existence while calcium and bicarbonate ions
tend to limit attack. The amount of dissolved oxygen is another
important element because oxygen stimulates the corrosion
process. Temperature affects corrosion by influencing the
chemical composition and physical properties of the corrosive
solution, the nature of deposits and the behavior of the
metal.
The Department of Transportation has defined a corrosive
material as one that corrodes a low carbon steel (SAE 1020)
at a severe rate, i.e., greater than 0.250 inch per year at a
test temperature of 130" F (49 CFR 173.240.). The rate of
0.250 inch per year was selected by DOT because experience
indicated that it represents a severe rate of corrosion. SAE
1020 steel was chosen as a test material by DOT because it is
used frequently in the manufacture of steel drums utilized in
transportation, and the 130* test temperature was selected
because that level may be encountered during transportation
of hazardous materials.
EPA files contain numerous descriptions of damage
incidents involving the use of steel drums to store, transport
and dispose of hazardous waste. The Agency believes that the
rate at which a waste corrodes a material commonly used in
container construction is a suitable measure of the hazardous-
ness of the waste. The DOT metal corrosion standard was
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adopted because it represents an appropriately severe rate of
corrosion, and the required test conditions adequately reflect
conditions likely to be encountered during transportation,
storage and disposal of wastes. An additional consideration
is the desire of the Agency to maintain consistency with
other regulations whenever practicable.
4. Additional Considerations for Development of a
Corrosiveness Characteristic.
(a) Direct Measurement of Tissue Damage
The Agency considered proposing a corrosive character-
istic which would directly address tissue damage. A standard
technique referenced by Federal agencies and several States
employs the application of the suspected corrosive to the
bare, intact skin of albino rabbits. The animals are exposed
for a specified period of time after which an assessment of
tissue damage is made (16, 17, 18). Conduction of the test
requires maintenance of special facilities and the use of
skilled personnel to evaluate the extent of injury. The
Agency believes that performing this type of testing on each
waste stream 'would add little to the scope of the corrosivity
definition and be unnecessarily burdensome to many members
of the regulated community. For waste disposal purposes,
relating tissue damage to an easily measurable characteristic
such as pH is the more practical approach because the hydrogen
ion or hydroxyl ion concentration is related to the degree of
injury. The pH provision will not encompass all substances
that damage tissue, but corrosive substances often display
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other hazardous characteristics that will bring them into
the hazardous waste net. For instance, corrosive metal
salts such as the arsenicals, chromates and mercurials proba-
bly will be covered by the toxicity characteristic.
(b) Acidity and Alkalinity
During the development of these regulations, it was
suggested that the corrosiveness characteristic should
address the percent acidity or alkalinity of the wastes
in addition to the pH. Percent acidity or alkalinity
provides an indication of the capacity of a liquid waste to
resist a change in pH (buffering capacity). Because the
Agency did not have adequate information concerning the
necessity of addressing acidity and alkalinity as a component
of its hazardous waste definition and had no technical basis
upon which to establish levels of hazard, comments on this
issue were solicited in the preamble to the proposed regula-
tions. A few comments favored adding a. acid i ty / alkal inity
provision to the pH characteristic because it would provide
useful information for disposal purposes. Most comments,
however, stated that addressing acidity and alkalinity would
not add significantly to the determination of hazard and
would necessitate the use of somewhat -more costly and compli-
cated measurement techniques than pH alone.
The Agency agrees that the addition of an acidity/alkalinity
determination to the pH provision of the corrosivity definition
is not necessary. Although acidity and alkalinity have some
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bearing on the manner in which these wastes are disposed,
they add little to the assessment of the hazard posed during
transportation, storage and initial disposal. Additionally,
because the ability of a waste to retain low or high pH is as
much a function of its disposal environment as of its percent
acidity/alkalinity the Agency knows of no scientifically
valid basis upon which to establish hazardous threshold levels
of percent acidity/aIkalinity. Therefore the Agency has
elected not to include percent acidity/aIkalinity in the
definition.
(c) Corrosiveness of Solids
The Agency considered making the pH provision of the
corrosiveness characteristic applicable to wastes in solid
form which are capable of forming aqueous solutions of low
or high pH once disposed. Estimates in the Agency's possession,
however, indicate that approximately 90% of all hazardous
wastes are in liquid or in semi-liquid form (19). The Agency
therefore solicited comments in the preamble to the proposed
regulations on the desirability of including solids in the
pH provision of the corrosiveness characteristic. The few
comments that were received in response to this inquiry
favored the inclusion of solids in the corrosiveness definition,
but did not describe situations where damage would be likely
to occur as a result of improper disposal of such wastes.
Upon consideration of these comments, the Agency has
concluded that there is no demonstrated need to address
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solids which may become corrosive in its corrosiveness definition
at this time. Liquid wastes constitute by far the greater
percentage of hazardous wastes and have a more immediate
potential to effect mobilization of toxic substances in the
environment. Furthermore, corrosive solids are not as likely
to cause problems as liquid wastes because the ability of a
solid to form an aqueous solution of high or low pH varies
with its physical and chemical characteristics and the manage-
ment conditions. The1RCRA prohibition against open dumping
coupled with the requirements for proper management of both
hazardous and non-hazardous wastes under the Section 3004
and 4004 regulations will reduce the risk of damage to the
environment from these wastes. Additionally, some corrosive
solids will probably be subject to the regulations because
they exhibit other hazardous characteristics, e.g., toxicity.
EPA will continue to seek additional information on the
hazards posed by wastes in solid form capable of generating •
solutions with high or low pH and will consider specific
regulatory measures if the need for more control becomes
apparent.
IV. Test Methods
A. pH
pH is measured by colorimetric or eleetrometric
means. Colorimetric techniques have severe limitations which
make them inappropriate for the pH determination of wastes.
They are subject to severe interference from turbidity, color,
high saline content, colloidal matter, free chlorine and
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various oxidants and reductants. In addition, a single
indicator is often limited to a relatively narrow pH range.
An acceptable method of pH measurement by electrometric
technique is described in Methods for Analysis of Water and
Wastes (EPA-600/4-79-020). pH is determined using either a
glass electrode with a reference potential or a combintion
electrode. The glass electrode is relatively free from most
types of interference, but may display impaired response
under certain conditions. The alkaline error encountered at
pH values above 10 can be diminished by using "low sodium
error" electrodes. Ambient temperature and the temperature
of the sample also influence electrometric measurement.
The effect caused by the alteration in electrode output at
various temperatures can be controlled by using instruments
with a temperature compensation feature. The variation in
temperature of the individual samples cannot be controlled;
therefore, sample temperature and pH should be recorded as
each sample is measured. Other sources of interference include
coatings of oily material or particulate matter on the elec-
trode and reduction of electrode life due to attack by solu-
tions which corrode glass. These can be minimized by proper
cleaning of the electrode.
The form of the substance to be measured should be taken
into account during a determination of pH. Blockage of the
liquid junction between the salt bridge and the test solution
must be prevented when measuring the pH of suspensions, sols
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or gels. Suspensions of highly charged sediments such as
soils or ion exchange resins may not give a true pH reading; •
the solution should be allowed to settle and the pH of the
supernatant measured (20).
Measurement of pH is a routine laboratory technique for
which a wide variety of instruments is available. A precision
of +_ 0.02 pH unit and an accuracy of _+_ 0.05 pH unit can be
achieved, but + 0.1 pH unit represents the limit of accuracy
under normal conditions. Therefore, pH values should be
reported to the nearest 0.1 pH unit (21).
B. Metal Corrosion
For purposes of hazardous waste definition, EPA
believes that it should employ a metal corrosion test which
indicates the general corrosion of a metal frequently used in
the manufacture of hazardous waste containers. Coupon
corrosion testing is designed for this purpose. Other
procedures are available to test for special metallurgical
phenomena, but they are more useful in the development of
specific container standards.
NACE Standard TM-01-69 describes a simple immersion test
to determine rate of corrosion. The procedure is not completely
standardized because it was designed to test the suitability
of metals for a variety of uses. Although the standard is
commonly employed as a method to detect the corrosiveness of
a solution of known composition on a certain metal, its flexi-
bility makes it suitable for determining the corrosiveness
of a mixture of unknown composition such as a waste.
23
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The NACE standard gives recommended practices for
sample preparation, type of equipment, and test conditions.
Duplicate metal coupons are first cleaned and weighed. The
solution is placed in an apparatus consisting of a flask, a
reflux condenser, a thermowell, a heating device and an
appropriate specimen support system. The preferred minimum
volume to area ratio is 40 millimeters of solution per square
centimeter of specimen. The specimens are exposed to the
test solution at a temperature of 55eC (130" F). Corrosion
should not be allowed to proceed to a point where the original
specimen size or exposed area is drastically reduced or the
metal is perforated. Aeration is unnecessary, and corrosive
constituents do not need to be replenished because metal
waste containers are likely to be in contact with a limited
amount of solution.
At the end of the exposure period, the coupons are
removed from the test environment, then cleaned and weighed.
The corrosion rate can be calculated by the following equation:
millimeters per year (mmpy) = weight lossx(0.268)
(area) (t ime)
Weight loss is in milligrams, area is square inches of exposed
metal surface and time is hours exposed
V. Comments on the Proposed Regulations
Generally, comments on the proposed regulation can be
placed in several broad categories. The greatest number of
responses concerned the proposed pH limits. Others addressed
24
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the establishment of a characteristic that would encompass
acidity and alkalinity, solids which form aqueous solutions
of high or low pH or a direct measure of tissue damage. A
few comments suggested that neither pH or the metal corrosion
provision is appropriate for defining corrosion.
A. pH Limits
o The proposed pH limits are unnecessarily
restrictive.
A great many comments advocated extending the acceptable
pH range. These comments have been fully addressed above and
need not be further addressed here.
o The Agency should define the term "aqueous" waste
The pH characteristic is applicable only to aqueous waste
because pH relates to the hydrogen ion activity in a solution.
A few comments suggested that EPA specifically define "aqueous"
in terms of viscosity or percent water. The Agency has not
developed a specific definition because of the widely varying
physical and chemical oroperties which influence the form of
wastes. Those who generate, treat, store or dispose of a
waste can best determine whether it is in a suitable form for
pH measurement.
o Corrosiveness is not typically defined in
terras of pH.
A few comments stated that, in the correct technical
sense, corrosion is an electrochemical reaction between the
environment and a metal surface; pH is not, therefore, a
standard measure of corrosiveness. The Agency does not agree
that the concept of corrosiveness is so limited. As stated
25
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previously, the Agency believes that the definition of a
corrosive waste should embrace both hazards associated with
metal corrosion and hazards associated with high and low pH.
A waste exhibiting either a very high or very low pH may
corrode the skin tissue of waste handlers. pH is also a
significant factor in solubilization of heavy metal salts
which results in increased mobility of toxic substances in
the environment. In addition improper disposal of wastes ex-
hibiting very high or low pH values can cause dangerous chemical
reactions in landfills. Establishing pH limits appears to be
the most effective way to address the various concerns.
o pH limits should address organic wastes.
Some comments suggested that the pH limit should address organic
wastes. If an organic waste is in an aqueous solution it will
be subject to the pH provision.
B. Tissue Damage
o The regulations should address tissue damage
in a more direct manner.
Some comments stated that the corrosiveness of some
substances which damage human tissue will not be adequately
indicated by a pH measurement. As discussed previously, the
Agency considered adopting the skin corrosion test referenced
by the Food and Drug Administration and the Department of
Transportation, but concluded that relating tissue damage to
an easily measurable characteristic such as pH is a more
reasonable approach for waste disposal purposes. Not all
26
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substances capable of damaging human tissue will be encompassed
by the pH provision. However, wastes may display one or
more of the other hazardous characteristics or possess
qualities which cause them to be listed as hazardous wastes.
Several comments mentioned the Consumer Product Safety Commission
detergent toxicity survey which found a relationship between
pH and corrosiveness to tissue, but did not find a correlation
strong enough to use for regulation of detergent products.
The Agency believes that inasmuch as its pH provision addresses
not just tissue damage but also such things as the solubilizat ion
of toxic materials and the causation of dangerous chemical
reactions, use of pH as a barometer of tissue damage is both
reasonable and justified.
C. Acidity/Alkalinity
o The regulations should address acidity and
alkalinity.
Several comments addressed the addition of acidity and
alkalinity to the pH criterion. These comments have been
fully addressed above and need not be further addressed
here .
D. Corrosiveness of Solids
o The regulations should address solids which may
form aqueous solutions of high or low pH and solids
which are corrosive to metal and human tissue.
A number of comments addressed the desirability of naking
the pH provision of the corrosiveness characteristic applicable
to solid wastes as well as liquid wastes. These comments
have been fully addressed above and need not be further addressed
27
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here .
E. Metal Corrosion Provision
The Agency received a number of comments on the
metal corrosion provision, many of which wanted to inject
management practices into the metal corrosion standard. Some
commenters felt that the metal corrosion test should apply
only to containerized waste. Others believed that the test
should be performed on containerized materials using the
specific material from which the container is made as the
test mat eri al.
The Agency has made the metal corrosion provision
applicable to non-containerized wastes because such wastes
are capable of corroding the containers of co-disposed wastes.
The Agency has chosen steel as a test material because steel
is commonly employed in the manufacture of steel drums and
steel drums are frequently used to store and dispose of
hazardous waste. Using the specific material from which a
generator's containers are made as the test material for the
metal corrosion test would make the hazardousness of the
waste too dependent upon the actual management practices
employed by the generator. It must be emphasized that the
metal corrosion provision constitutes an attempt to define
which wastes are hazardous if improperly managed, that is,
which wastes are hazardous under some likely mismanagement
scenario. The definition is not an attempt to set out standards
for proper management; this is accomplished by the Section
3004 regulations.
28
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One commenter remarked that the 130* test temperature
specified by the metal corrosion provision is too high.
The Agency picked that temperature to reflect conditions
encountered during transportation of hazardous wastes and in
landfills. Studies show that temperatures in that range are
encountered in landfills. (22, 23).
Several comments were made concerning the choice of
steel as a test material. One comment stated that the
corrosion rate of steel is influenced by many factors. The
Agency is aware that corrosion is a complex phenomenon and
has chosen the NACE test because that test, by giving a
general indication of the ability of a waste to corrode metal,
ably accoraodates the many factors influencing corrosion. One
comment states that otherwise harmless wastes such as salt
water will corrode steel but provides no information on the
corrosion rate of such harmless wastes. Lacking such
information, the Agency is unable to evaluate the merit of
this contention. In any event, the Agency is convinced that
any waste which exhibits as severe a corrosion rate as 6.35
mm/year must be segregated from containers holding other
hazardous wastes during transportation, storage and disposal.
One comment suggested that the metal corrosion test is
unnecessary because steel drums will invariably corrode in a
landfill environment. The Agency disagrees. The metal
corrosion provision is designed to address hazards associated
with transportation, storage or disposal as well as hazards
29
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associated with placing containerized wastes in landfills.
Furthermore, the Agency doubts that the corrosive influences
found in a landfill exert anything close to the corrosive
effect exerted by wastes exhibiting a corrosion rate of 0.250
inch per year.
o When an aqueous waste, is extremely thick or
is not amenable to stirring to obtain homo-
geneity, the solids should be allowed to
settle and the pH of the supernatant measured.
Some comments suggested that when an aqueous waste is
extremely thick or is not amenable to stirring to obtain
homogeneity (as in the case of a slurry), the solids should
be allowed to settle and the pH test applied to the supernatant
liquid. The Agency finds this an acceptable practice to
prevent interference caused by blocking of the electrode.
G. General Comments
o Permit writers should judge the hazard
associated with wastes exhibiting high or
low pH levels on a case-by-case basis.
One comment suggested that permit writers should judge
the hazard associated with pH on a case-by-case basis. The
purpose of RCRA Section 3001 is to define a hazardous vaste
in terms of physical, chemical and biological properties.
Actual management standards will be established under Section
3004. Regulations promulgated pursuant to Section 3005 will
provide sufficient flexibility in the permitting process to
accommodate various management methods for hazardous wastes
as long as those methods protect human health and the environment
30
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Corrosive wastes should not be classified as
hazardous if properly managed.
Several comments argued, in effect, that corrosive wastes
which are properly managed or which do not otherwise fit the
mismanagement scenario envisioned by the corrosiveness
definition should not be classified as hazardous. One comment
stated that corrosive wastes should be classified as hazardous
depending on the containers used. Other comments argued that
the definition should be revised to exclude wastes which are
not transported, stored or disposed with other wastes. As
noted' above, in defining hazardous corrosive waste, the Agency
has attempted to reach those wastes which are hazardous if
mismanaged under some likely mismanagement scenario. The
purpose of the definition is to bring such wastes into
the hazardous waste management system set up by Sections
3002, 3003, 3004, and 3005 of the Act -- not to specify
management practices. If management practices were made part
of the definition so that properly managed wastes were excluded
from the definition, the effectiveness of the management
system created under Sections 3002, 3003, 3004, and 3005
might well be vitiated, since properly managed wastes would
be excluded at the outset from the continuing supervision and
control provided by the management system thus prejudicing
the Agency's ability to ensure continued compliance with
these proper management practices. The regulations
under Section 3004 and 3005 will be sufficiently flexible to
31
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accomodate wastes which are properly managed or which otherwise
don't fit the mismanagement scenario envisioned by the
corrosiveness definition.
In a closely related comment, one commenter stated that
since disposal of liquids in landfills is not permitted,
liquid corrosives do not really present a hazard. This
argument is largely circular because if liquid corrosives
were not classed as hazardous, they could readily be disposed
of in landfill environments.
o Specify measurement of pH within +^ 0.5 pH units
One comment suggested that the Agency should specify
measurement of pH within +_ 0.5 pH units. Under normal
conditions, pH should be measured to the nearest 0.1 of a
unit. Measurement can be made more precisely if necessary.
The Agency sees no reason to permit measurement within +_ 0.5
pH uni t s .
Metal Corrosion
o NACE Standard TM-01-69 is not completely
standardized and permits variation in a
number of test conditions.
One comment argued that the NACE Standard TM-01-69 permits
variation in a number of test conditions and that therefore
the test is not clearly enough defined. The Agency recognizes
that this is the case and, to correct the problem, has more
clearly defined the appropriate test conditions. A description
of these conditions is found in "Test Methods for Evaluating
Solid Waste" SW-846.
32
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o The generator should be allowed to use a
corrosion rate given in the Corrosion Data
Survey as a substitute for employing the
NACE test.
One comment argued that the generator should be allowed
to use a corrosion rate given in the Corrosion Data Survey as
a substitute for the NACE test. The Agency does not agree.
The Corrosion Data Survey gives corrosion rates for water
dilutions of pure compounds (24). Contaminants, however, may
exert a significant effect on corrosion rate. Because wastes
are often complex mixtures rather than simple aqueous solutions,
the Agency believes that actually performing the NACE test
provides a more appropriate indication of hazard.
o The corrosiveness of the waste is to be
determined at the point of generation.
The corrosiveness characteristic should not
apply to wastes which lose their corrosive
nature after a certain period of time.
One comment asked whether the corrosiveness of the waste
is to be determined at the immediate point at which it becomes
a waste or in the form in which the generator disposes of it.
Another comment suggested that the corrosiveness characteristic
should not apply to wastes which lose their corrosive nature
after a certain period of time. A waste is defined as
hazardous at the point of generation unless it is piped
directly to a treatment facility. Where wastes are stored
before treatment or transported in other than a closed pipe
system, the Agency believes that the hazardous waste
characteristics must apply in order to protect human health
and the environment. The Agency has not exempted from the
33
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corrosiveness characteristic wastes which lose their corrosive
nature after a period of time because (a) such wastes present
a hazard, at least initially (b) the Agency has no criteria
for determining which corrosives will persist and which will
not .
o The corrosiveness characteristic should not
be applicable to certain wastes.
Several comments stated that the corrosiveness characteristic
should not be applicable to certain wastes. Some comments
stated that the corrosivenness characteristic should not
apply to fly ash since it is not containerized and its disposal
does not involve human contact. As discussed previously,
for the purpose of hazard definition the corrosiveness charac-
teristic applies whether a waste is containerized or not or
whether waste handlers are involved. If fly ash does not
corrode steel, and exhibits a pH less than 12.5 then it is
not a hazard within the meaning of the corrosiveness character-
istic.
It was suggested that organic acids be exempted from
application of the corrosiveness characteristic because they
tend to degrade under landfill conditions. Even if degra-
dation does occur the Agency is concerned with storage and
transportation as well as disposal. Furthermore, Appendix D
illustrates that unregulated co-disposal of organic acids
and other substances can result in harmful consequences such
as generation of heat or toxic gases, fire and explosion.
Some comments suggested exempting drilling fluid because
34
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the pH of the material decreases when it is placed in a reserve
pit. No data were given on the pH of drillng fluid before
discharge to the pit. The comment contends that this is a
treatment procedure. As such, it may be acceptable under
Section 3004 standards. Hazardous was-e definition standards
under Section 3001, however, are applicable at the point at
which a waste is generated. The Agency sees no reason why
the corrosiveness characteristic should not be applicable to
drilling fluids if they meet the provisions of the characteristic
o Separate the pH and metal corrosion provision
in the regulations because they measure differ-
ent effects.
One comment suggested separating the pH and metal
corrosion provisions in the regulations because they measure
different effects. The Agency sees no reason for doing this.
Each provision covers a type of corrosion, i.e. corrosion to
living tissue or corrosion to metal surfaces and both types
are properly subsumed under one characteristic.
o Determine the overlap between the pH provision
and the metal corrosion provision to see
whether the metal corrosion provision can
be el iminated.
4
One comment suggested that the Agency determine the
overlap between the pH provision and the netal corrosion
provision to determine whether the metal corrosion provision
can be eliminated. The Agency sees no justification for
this approach. While pH is an important factor in metal
corrosion, the two provisions address different effects and
are 'not necessarily mutually inclusive.
35
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H. Summary of Data on the Metal Corrosion Test Published
in the NUS Report* and Response to Comments Received
on that Noticed Report
As part of the testing program carried out under this
contract, EPA had a sample of spent pickle liquor and a sample
of spent caustic tested by two laboratories to determine the
rate at which these wastes corrode SAE 1020 steel. As
expected, the coupons exposed to the spent caustic showed no
appreciable corrosion. (Alkaline wastes are not especially
corrosive to steel.) The coupons exposed to the spent pickle
liquor corroded at rates of 509 inches per year in Lab J and
220 inches per year in Lab K. The difference in corrosion
rates is attributed to variations in test conditions and the
extreme corrosiveness of the test medium. The corrosiveness
characteristic provides that a liquid waste is hazardous if
it has a corrosion rate greater than 0.25 inch per year.
One comme.nter stated that the difference between the
corrosion rate of the spent pickle liquor samples indicated
that the NACE test is not reproducible. The Agency does not
agree. The reproducibiity of this test cannot be determined
»
on the basis of the NUS test performance since variability
is to be expected at the extremely high corrosion rates
found by the two laboratories. The important point is that
the spent pickle liquor in both samples flunked the corrosivity
*"Evalution of Solid Waste Extraction Procedures and Various
Hazard Identification Tests (Final Report)", NUS Corporation,
September, 1979 .
36
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characteristic by three orders of magnitude and thus would
be considered a hazardous waste.
VI. Promulgated Regulation
The Agency has reviewed the comments on the proposed
regulations and agrees that the pH limits should be lowered
from 3.0 to 2.0 and increased from 12.0 to 12.5. The
corrosiveness characteristic is now defined as follows:
§261.22 Characteristic of corrosivity
(a) A solid waste exhibits the characteristic of
corrosivity if a representative sample of the waste has either
of the following properties:
(1) It is aqueous and has a pH less than or
equal to 2 or greater than or equal to 12.5, as determined by
a pH meter using either the test method specified in the
"Test Methods for the Evaluation of Solid Waste, Physical/
Chemical Methods"* (also described in "Methods for Analysis
of Water and Wastes" EPA 600/4-79-020, March 1979), or an
equivalent test method approved by the Administrator under
the procedures set forth in §§260.20 and 260.21.
(2) It is a liquid and corrodes steel (SAE
1020) at a rate greater than 6.35 mm (0.250 inch) per year at
a test temperature of 55cC (130CF) as determined by the test
method specified in NACE (National Association of Corrosion
Engineers) Standard TM-01-69** as standarized in "Test Methods
*This document is available from Solid Waste Information,
U.S. Environmental Protection Agency, 26 W. St. Glair Street,
Cincinnati, Ohio 45268.
**The NACE Standard is available from the National Association
of Corrosion Engineers, P.O. Box 986, Katy Texas 7740
37
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for the Evaluation of Solid Waste, Physical/Chemical Methods,"
or an equivalent test method approved by the Administrator
under the procedures set forth in §§260.20 and 260.21.
(b) A solid waste that exhibits the characteristic of
corrosivity, but is not listed as a hazardous waste in Subpart
D, has the EPA Hazardous Waste Number of D002.
38
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References
1. Bates, R. G., Determination of pH, Theory and Practice.
2nd Edition. John Wiley & Sons, New York, 1973.
2. Lewis, G. K., Chemical Burns. American Journal of Surgery
95:928-937, 1959.
3. Encyclopedia of Occupational Health and Safety. Volume 1.
Geneva, International Labor Office, 1971-72. pp. 220-221.
4. MrCreanney, W. C., Skin Care. In V. Handley, ed. Industrial
Safety Handbook. Maidenhead, Berkshire, England, McGraw
Hill, 1969. pp. 399-403.
5. • Birmingham, D. J., Acids, alkalis, oils and solvents. In
P. Cantor, ed. Traumatic Medicine and Surgery for the
Attorney. Washington, Butterworth, Inc., 1962. pp. 364-370.
6. U.S. EPA. Office of Water Programs Operations. Oil and
Special Materials Control Division. Open Damage Incident
Files.
7. Report to Congress. Waste Disposal Practices and Their
Effects on Groundwater, U.S. EPA, OWS/OSWMP, January, 1977.
8. Geraghty and Miller. -The Prevalence of Subsurface Migration
of Hazardous Chemical Substances at Selected Industrial
Waste Land Disposal Sites. EPA/530/SW-634. October, 1977.
9. Pourbaix, Marcel. Atlas of Electrochemical Equilibria in
Aqueous Solutions. Pergamon, Great Britain, 1966.
10. SCS Engineers, Chemical Speciation of Contaminants in FGD
Sludge and Wastewater. U.S. EPA., SHWRD/MERL, Contract
Number 68-03-2371 March, 1978.
11. Curry, Nolan. Guidelines for Landfill of Toxic Industrial
Sludges. Presented at the Twency-eighth Industrial Waste
Conference, Purdue University, Xav, 1973.
12. Draft Report. A Method for Determining Hazardous Wastes
Compatibility. U.S. EPA Grant Ku-ber R804692. 1979.
13. Sax, Irving, Dangerous Properties of Industrial Materials
4th Edition, Van Nostrand Reinholc. New York, 1975.
14. National Academy of Sciences and National Academy of
Engineering.. "Acidity, Alkali-it-, and pH." Water
Quality Criteria. EPA R3-73-033. March, 1973.
-------
15. Butler, G. and H. Ison, Corrosion and its Prevention
in Waters. Reinhold, New York. 1966.
16. 49 CFR 173.240 Department of Transportation.
17. 21 CFR 191.1 Food and Drug Administration.
18. 16 CFR 1500.3 Consumer Product Safety Commission.
19. A Study of Hazardous Wastes in Class I Landfills. EPA
600/2-78-064. June, 1978.
20. Mattack, A. pH Measurement and Titration. New York,
MacMillan, 1961. p. 257.
21. Standard Methods for the Examination of Water and Waste-
water, 14th Edition (1975).
22. Blannon, J.C. and M. L. Peterson. Survival of Fecal
Coliforras and Fecal Streptococci in a Sanitary Landfill.
Solid and Hazardous Waste Research. April 12,' 1974.
23. Boone County Field Site Interim Report - Test Cells
2A, 2B, 2C and 2D. EPA 600/2-79-058, July, 1979. p. 84.
24. Corrosion Data Survey. National Association of Corrosion
Engineers. 1967.
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Appendix A
CORROSIVENESS - STATE IDENTIFICATION CRITERIA
State
PH Limits
Test for
Corrosion of
Living Tissue
Test
for Metal
Corros ion
California -
Hazardous Waste
Criteria and
Definitions
Illinois - Tenta-
tive Land Dispo-
sal Criteria
Kentucky - Draft
Hazardous Waste
Regulations
Maine - Hazardous
Waste Management
Rules
Michigan - Pro-
posed Hazardous
Waste Regulations
Minnesota - Haz-
ardous Waste
Regulations
Oregon - Draft
Hazardous Waste
Regulat ions
Rhode Island -
Proposed Hazard-
ous Waste Gen-
erator Rules
and Regulations
pH < 2 or > 12
where pH is < 3
or > 10 percent
acidity or alka-
linity must be
determined
pH
3 or
12
pH < 3 or >_ 12
T
pH < 3 or > 12
pH _< 3 or >_ 12
Yes
16 CFR 1500.41
Yes
49 CFR 173.240
Yes
16 CFR 1500.41
49 CFR 173.240
pH < 3 or >_ 12 |
(has provisions I
for liquids, I
solids and gases) I
Yes
Yes
Yes
Yes
Yes
Yes
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CORROSIVENESS - IDENTIFICATION CRITERIA
State
PH Limits
Corrosion of
Living Tissue
Metal
Corrosion
Tennessee - Pro-
posed Hazardous
Waste Regulations
pH <_ 3 or >_ 12
Yes
Texas — Hazardous
Waste Guidelines:
Waste Evaluation
and Classifica-
tion
pH < 2.5 or > 12
Yes
Washington - Haz-
ardous Waste
Regulations
pH < 3.0 or > 11.0
(substances which
yield those pH
levels when mixed
with an equal
weight of water)
Yes
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APPENDIX B
EXAMPLES IN WHICH CORROSIVE WASTES CAUSED TISSUE DAMAGE
Pennsylvania 1975
An inspector attempting to halt unauthorized disposal
of a drum in North Cordorus Township was splashed by the
contents of the drum as it ruptured during compaction. The
inspector sustained burns on the face and neck.
New Jersey 1974
During the first ten months of the year/ seven chemical
waste disposal injuries were noted in the logs of a landfill
Injuries included eye irritation and chemical burns from
exposure to corrosive wastes.
Texas 1971
Barrels containing chemical wastes were caught in
shrimpers' nets in the Gulf of Mexico. Physical damage to
nets and equipment occurred, and exposed shrimper crewmen
experienced skin burns and eye irritation.
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APPENDIX C
CASE HISTORIES OF ACCIDENTS CAUSED BY
MIXING OF INCOMPATIBLE WASTES (12)
1. Violent. Reaction, Pressure Generation in Tank Truck
In Richmond, California, a hazardous waste "hauler mixed, in
his 30-barrel tank truck, a liquid waste containing butyl
acetate in xylene with an etching waste containing
sulfuric acid, nitric acid and hydrofluoric acid.
A hydrolysis reaction took place. The reaction generated
pressure in the tank and blew the safety relief value
while the truck was travelling through a residential
area. A private residence was sprayed with the hazardous
mixture. No one was injured, but considerable clean-up
and repainting of the-house was required.
2. Formation of Toxic Gas in Sanitary Landfill
In Los Angeles County, a tank truck emptied several
thousand gallons of cyanide waste onto refuse at a sanitary
landfill. Another truck subsequently deposited several
thousand gallons of acid waste at the same location.
Reaction between the acid and the cyanide evolved large
amounts of toxic hydrogen cyanide gas. A potential
disaster was averted when a local chlorine dealer was
quickly called to oxidize the cyanide with chlorine
solution.
3. Formation of Toxic Gas in Excavated Site
A load of acidic aluminum sulfate waste was. inadvertently
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discharged into an excavation already containing some sulfide
waste. Hydrogen sulfide was released, and the lorry driver
died in his cab at the landfill site.
4. Formation of Toxic Gas and Explosion in Waste Tank
Sulfide waste was added to a soluble oil waste in a tanker
and subsequently added to other oily wastes in a tank.
Later treatment of the oil with acid to break the emulsified
oil resulted in evolution of hydrogen sulfide. Two
operators were briefly affected by the gas. There
was also an explosion in the tank.
5. Formation of Toxic Gas at a Landfill
At a sanitary landfill near Dundalk, Maryland, a 2,000
gallon liquid industrial waste load containing iron
sulfide, sodium sulfide, sodium carbonate and sodium
thiosulfate along with smaller quantities of organic
compounds was discharged into a depression atop an earth-
covered area of the fill. When it reached eight to ten
feet below the point of discharge, the liquid started
to bubble and fume blue smoke. The smoke cloud quickly
engulfed the truck driver and disabled him. Several
nearby workers rushed to his aid and were also felled.
During the clean-up operation, one of the county fire— •
fighters also collapsed. All six of the injured were
hospitalized and treated for hydrogen sulfide poisoning.
It was not determined whether the generation of hydrogen
-------
sulfide was due to the instability of the waste or the
incompatibility of the waste with some of the landfill
materials. The pH of the waste was measured to be 13
before it left the plant.
Formation of Toxic Gas in a Disposal Well
*
At a land disposal site in Southern California, a tanker
was observed unloading a waste listed as "waste acid
(5% HC1)" into a bottomless tank through an open stack
above the ground. Shortly after the unloading operation
commenced, yellowish-brown clouds of nitrogen dioxide
began to emanate from the open stack. The reactions
appeared to have subsided when the discharging of the
wastes ceased. However, an hour later more NC>2 started
to spew from the stack. The emission was halted by
filling the stack with soil. There were no injuries,
but the incident created a significant air pollution
problem. Complaints from nearby business were received
and a factory was evacuated.
Fire, Dispersal of Toxic Dusts from Leaky Containers
At a dump in Contra Costa County, California, a large
number of drums containing solvents were deposited in a
landfill. In the immediate area were leaky containers•
of concentrated mineral acids and several bags containing
beryllium wastes in dust form. The operators failed
to cover the waste at the end of the day. The acids
reacted with the solvents during the night, ignited
-------
them and started a large chemical fire. There was possible
dispersion of beryllium dust into the environment.
Inhalation, ingestion or contact with beryllium dust by
personnel could have led to serious health consequences.
8. Violent Eruption in Waste Drum
At an engineering works, hot chromic.acid waste was in-
advertently added to a drum containing methylene chloride
waste from degreasing operations. There was a violent
eruption resulting in chemicals being sprayed locally
in the workshop but no one was harmed.
9. Nitrogen Oxide Generation at a Sanitary Landfill
A truck driver picked up a load of "nitric acid" from an
automotive specialities manufacturing company in early
July 1976 and delivered it to a site in Southern California
for well disposal. The well accepted approximately 50
gallons and then "pressurized". The driver then took
the remainder of the load to another landfill in Southern
California for trench disposal. Upon unloading, a reaction
took place which generated brown nitrogen dioxide fumes
which were carried by the wind and interfered with traffic
500 yards away. Towards the end of the month the same
driver picked up another load of the same type from the
same company and delivered it directly to the second
landfill site. Upon arrival at the weigh station, he
was instructed to tell the catapillar driver to "dig a
deep hole". The catapillar operator dug a hole approxi-
-------
raately 12 ft. deep, 12 ft. wide, and 20 ft. long into a
previously filled area. The truck driver said that he
observed damp ground and decomposing refuse in the
trench. The driver then unloaded his truck and backed
away from the trench as he did not want to be exposed to
the hazard he had observed on the previous occasion. He
observed a dense brown cloud emanating from the trench
and could not return to his truck until its contents had
been drained and the hazard reduced. A chemical analysis
of the retained sample showed that it contained approximately
70% nitric acid and 5% hydrofluoric acid along with
aluminum and chromium. The sample was funing when it
was taken from the truck.
10. Cyanide Generation at A Sanitary Landfill
A standard procedure at a Southern California disposal
site for handling liquid wastes containing cyanides
and spent caustic solutions was to inject these loads
into covered wells dug into a completed section of a
sanitary landfill. Routine air sampling in the vicinity
of the wells detected low levels of HCN. Sampling in the
well head detected more than 1000 ppm HCN. No cyanide
was detected during addition of the spent caustic to - .
a new well. On the basis of these discoveries, use of
the wells was discontinued. The cyanide gas was ap-
arently formed in the well as a result of lowering of
the pH of the waste by CC>2 and organic acids produced
-------
in the decomposition of refuse.
11. Nitric Acid and Alcohol Cause Explosion of Tank Car;
While transfering 64% nitric acid to a supposedly empty
tank car, the tank car exploded. An investigation
revealed that the tank car contained a small residual
of alcohol which was converted to acetaldehyde by the
acid. The heat of reaction vaporized the acetaldehyde
and subsequently ignited the acetal<*ehyde-air mixture
causing an explosion. No injuries or fatalities resulted.
12. Nitric Acid - Ammonia Fire Generate Toxic Fumes
In a Carroll County, Arkansas fertilizer warehouse, a
mixture of ammonia and nitric acid ignited and destroyed the
plant. Toxic fumes generated by the blaze forced the
evacuation of the town's residents. No injuries or fat-
alities were reported.
13. Vacuum Truck Rupture Caused by Formation of Hydrogen Gas
In Los Angeles, a vacuum truck containing an unknown
quantity of residual wastes picked-up a spent sulfuric
acid metal stripping solution. On the way to the disposal
site a violent explosion ocurred, rupturing the tank and
injuring the driver. Subsequent investigation revealed
that the residue in the tank prior to the pick-up of the
acid solution contained aluminum and magnesium turnings and
fines. The action of the acid on these metal particles
produced hydrogen gas and heat. Extreme pressure build-
up resulted in the violent rupture of the tank.
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APPENDIX D
REACTIONS BETWEEN ACIDS OR BASES AND
OTHER SUBSTANCES-POSSIBLE ADVERSE CONSEQUENCES (12)
MINERAL ACIDS + ALCOHOLS AND GLYCOLS
Dehydration reactions and displacement with the halide
result in heat generation.
MINERAL ACIDS -I- ALDEHYDES
Condensation reactions cause heat generation. Acrolein
and other unsaturated aldehydes polymerize readily.
MINERAL ACIDS + AMIDE
Hydrolysis of amide to the corresponding carboxylic
acid results in an exotherm.
MINERAL ACIDS + AMINES
The acid base reaction between these two types of
compounds forming the ammonium salts may be sufficiently
exothermic to cause a hazard.
MINERAL ACIDS + AZO COMPOUNDS
Amyl azo and diazo compounds decompose exothermically
upon mixing with strong mineral acids to yield nitrogen
gas and the corresponding amyl cation. Aliphatic azo and
diazo compounds/ particularly diazoalkanes, can polymerize
violently with heat generation. Organo azides can also
decompose exothermically with strong acid to form nitrogen
gas and the respective cations. An exotherm also results
from the acid-base reaction of hydrazines with mineral acids
-------
as hydrazines are comparable in base strength to ammonia.
Diazomethane is a particularly reactive compound in this group.
MINERAL ACIDS + CARBAMATES
Carbamates can undergo hydrolysis as well as decarboxylation
upon mixing with strong mineral acids. Both reactions are
exothermic and the latter can generate pressure if it occurs
in a closed container.
MINERAL ACIDS + CAUSTICS
The acid-base reaction between strong mineral acids and
strong caustics is extremely exothermic and can be violent.
Fires can result if the caustic substance is an alkoxide.
MINERAL ACIDS + CYANIDE
Inorganic cyanides rapidly form extrerrel.y toxic and flam-
mable hydrogen cyanide gas upon contact with mineral acids.
MINERAL ACIDS + DITHIOCARBAMATES
Acid hydrolysis of dithiocarbamate heavy metal salts with
strong mineral acids yields extremely flammable and toxic
carbon disulfide gas. An exotherm can be expected from the
reaction.
MINERAL ACIDS + ESTERS
Strong mineral acids in excess will cause hydrolysis and .
decomposition of esters with heat generation.
MINERAL ACIDS + ETHERS
Ether may undergo hydrolysis with strong acids exothermi-
cally.
-------
MINERAL ACIDS + FLUORIDES
Most inorganic fluorides yield toxic and corrosive hydrogen
fluoride gas upon reaction with strong mineral acids.
MINERAL ACIDS + HALOGENATED ORGANICS
Strong mineral acids in excess may cause decomposition with
generation of heat and toxic fumes of hydrogen halides.
MINERAL ACIDS + ISOCYANATES
Acid catalyzed decarboxylation as well as vigorous decompo-
sition can occur upon mixing of isocyanates with strong
mineral acids.
MINERAL ACID + KETONE
*
Acid catalyzed aldol condensation occurs exothermically.
MINERAL ACIDS 4- MERCAPTANS
Alkyl mercaptans are particularly reactive with mineral acids
yielding extremely toxic and flammable hydrogen sulfide gas.
Other mercaptans can yield hydrogen sulfide with excess strong
acids. Excess strong acid can also result in decomposition
and generation of toxic fumes of sulfur oxides.
MINERAL ACIDS + ALKALI AND ALKALINE EARTH METALS
The reaction of strong mineral acids wifb alkali and alkaline
earth metals in any form will result in a vigorous exothermic
generation of flammable hydrogen gas and possible fire.
MINERAL ACIDS 4- METAL POWDERS, VAPORS, OR SPONGES
Reactions of strong mineral acids with finely divided
metals or metals in a form with high surface area will result
-------
in vigorous generation of flammable hydrogen gas and possible
explosion caused by the heat of reaction.
MINERAL ACIDS + METAL SHEETS, RODS, DROPS. ETC.
Strong mineral acids will form flammable hydrogen gas upon
contact with metals in the form of plates, sheets, chunks,
and other bulk forms. The heat of reaction may ignite the
gas formed.
MINERAL ACIDS + NITRIDES
The aqueous fraction of strong mineral acids will- react with
nitrides evolving caustic and flammable ammonia gas. The
acid-base reaction of mineral acids and nitrides can also
evolve much heat and ammonia.
MINERAL ACIDS -1- NITRILES
Exothermic hydrolysis of nit-riles to the corresponding
carboxylic acid and ammonium ion is known to occur with
mineral acids. Extremely toxic and flammable hydrogen
cyanide gas may be evolved with such compounds as acetone,
cyanohydrin and propionitriles.
MINERAL ACIDS + UNSATURATED ALIPHATICS
Addition of mineral acids to alkenes usually results in
exothermic acid catalyzed hydration and partial addition of
the hydrogen halide or sulfates. Acetylenes are also sus-
ceptible to exothermic acid catalyzed hydration, forming the
corresponding aldehyde or ketone with possible addition of
the hydrogen halide in the case of halogen acids.
MINERAL ACIDS + ORGANIC PEROXIDES
Strong mineral acids can react with organic peroxides and
-------
hydroperoxides with enough heat generated to cause explosive
decomposition in the more unstable compounds. Oxygen can
also be generated.
MINERAL ACIDS + PHENOLS AND CRESOLS
Exothermic sulfonation reactions can occur with addition of
sulfonic acid to phenols and cresols. Substitution of the
hydroxyl with a halide can occur with addition of the halogen
acids. Excess strong acid can decompose phenols and cresols
with heat generation.
MINERAL ACID + ORGANOPHOSPHATES
Excess strong mineral acid can cause decomposition of organo-
phosphates, phosphothioate and phosphodithioates with heat
generation and possible toxic gas formation.
MINERAL ACIDS + SULFIDES
Extremely toxic and flammable hydrogen sulfide gas results
from the combination of mineral acids and sulfides.
MINERAL ACIDS + EPOXIDES
Acid catalyzed cleavage can occur, initiating polymerization
with much heat generated.
MINERAL ACIDS + COMBUSTIBLE MATERIALS
Dehydration and decomposition on addition of excess strong
mineral acid can cause heat and possible toxic gas generation,
'MINERAL ACIDS -I- EXPLOSIVES
Many explosives are extremely heat sensitive and can be
detonated by heat generated from the action of strong
mineral acids on these compounds.
-------
MINERAL ACIDS + POLYMERIZABLE COMPOUNDS
Strong mineral acids can act as initiators in the poly-
merization of these compounds. The reactions are exothermic
and can occur violently.
MINERAL ACIDS + STRONG OXIDIZING AGENTS
Many combinations of strong mineral acids and strong oxidizing
agents are sensitive to heat and shock and may decompose
violently. The halogen acids may be oxidized yielding
highly toxic and corrosive halogen gases, accompanied by
heat generation.
'MINERAL ACIDS + STRONG REDUCING AGENTS
Many reducing agents form flammable hydrogen gas on contact
with mineral acids. The heat generated can cause spontaneous
ignition. Some reducing agents such as metal phosphides and
inorganic sulfides evolve extremely toxic and flammable
fumes of phosphine and hydrogen sulfides, respectively.
MINERAL ACIDS + WASTE AND MISCELLANEOUS AQUEOUS MIXTURES
Much heat can be evolved upon solubilization and hydrolysis
of these acids.
OXIDIZING MINERAL ACIDS 4- ORGANIC ACIDS
These mineral acids can oxidize the hydrocarbon moeity of
organic acids with resulting heat and gas formation.
' OXIDIZING MINERAL ACIDS + ALCOHOLS AND GLYCOLS
Oxidation of the hydrocarbon moeity can occur resulting in
heat and gas formation. Nitration with nitric acid can take
place in the presence of sulfuric acid forming extremely
unstable nitro compounds.
-------
OXIDIZING MINERAL ACIDS + ALDEHYDES
Oxidation of the hydrocarbon raoeity can occur resulting in
heat and gas formation.
OXIDIZING MINERAL ACIDS + AMIDES
Oxidation with excess acid can result in heat generation and
formation of toxic fumes of nitrogen oxides.
OXIDIZING MINERAL ACIDS + AMINES
The acid-base reaction produces much heat and exhaustive
oxidation results in generation of heat and toxic fumes of
nitrogen oxide.
OXIDIZING MINERAL ACIDS + AZO COMPOUNDS
Azo compounds and diazo compounds are easily decomposed by
strong acids evolving much heat and nitrogen gas. . They are
very susceptible to oxidation and can evolve toxic fumes
of nitrogen oxides upon exhaustive oxidation. Hydrazines are
expecially susceptible to oxidation and inflame upon contact
with oxidizing agents. Many of the compounds in this group
such as diazomethane and the azides are very unstable and
can decompose explosively upon heating.
OXIDIZING MINERAL ACIDS + CARBAMATES
Carbamates can undergo exothermic hydrolysis and decarboxyla-
tion upon mixing with these acids. Exhaustive oxidation can
also result in formation of toxic fumes of nitrogen oxides,
and sulfur oxides in the case of thiocarbamates.
OXIDIZING MINERAL ACIDS + CAUSTICS
The neutralization reaction can be violent with evolution of
much heat.
-------
OXIDIZING MINERAL ACIDS + CYANIDES
Evolution of extremely toxic and flanmable hydrogen cyanide
gas will occur before oxidation.
OXIDIZING MINERAL ACIDS + DITHIOCARBAMATES
Acids will cause decomposition of dithiocarbamates with
evolution of extremely flammable carbon disulfide. Significant
heat may be generated by the oxidation and decomposition to
ignite the carbon disulfide.
OXIDIZING MINERAL ACIDS + ESTERS
Exhaustive oxidation of esters can cause decomposition with
heat and possible ignition of the more flammable esters.
Conversion to the organic acid and decarboxylation can also
occur.
OXIDIZING MINERAL ACIDS..+ ETHERS
Heat generated from the exhaustive oxidation of ethers can
ignite the more flammable ethers. These compounds can also
undergo exothermic acid catalyzed cleavage.
OXIDIZING MINERAL ACIDS + FLUORIDES
Gaseous hydrogen fluoride can result from a combination of
inorganic fluorides and these acids. Hydrogen fluoride is
extremely corrosive and toxic. Some heat can also be evolved.
OXIDIZING MINERAL + HALOGENATED ORGAKICS
These acids can cause oxidation and decomposition of
halogenated organics resulting in heat and generation of
extremely toxic fumes of hydrogen chloride, phosgene, and
other gaseous halogenated compounds.
-------
OXIDIZING MINERAL ACIDS + ISOCYANATES
Isocyanates may be hydrolyzed by the water in concentrated
acids to yield heat and carbon dioxide. They may also be
oxidized by these acids to yield heat and toxic nitrogen
oxides.
OXIDIZING MINERAL ACIDS + KETONES
Ketones can undergo exothermic aldol condensations under
acidic conditions. Oxidizing acids can cleave the ketone to
give a mixture of acids. Excess acid can cause complete
decomposition yielding much heat and gas. Fire can also
r esult.
OXIDIZING MINERAL ACIDS + MERCAPTANS
Extremely toxic and flammable hydrogen sulfide gas can be
formed by the action of the acid on mercaptans. Oxidation
of mercaptans and other sulfur compounds can result in formation
of toxic sulfur dioxide and heat.
OXIDIZING MINERAL ACIDS + ALKALI AND ALKALINE EARTH METALS
Extremely flammable hydrogen gas can be generated upon contact
of acids and these metals. The reaction of such a strong
oxidizing agent and strong reducing agents can be so violent
as to cause a fire and possibly an explosion.
OXIDIZING MINERAL ACIDS + METAL POWDERS, VAPORS, AND SPONGES
The action of acid on these metals produces hydrogen gas
and heat. Due to the large surface area of these forms of
metals, the reaction can occur with explosive violence.
OXIDIZING MINERAL ACIDS + METAL SHEETS, RODS, DROPS. ETC.
The reaction of acids on metals as sheets, plates, and other
-------
bulk forms can evolve hydrogen gas and some heat* Although
the reaction proceeds much slower than in the case of powders,
a definite fire hazard exists. Many metals are attacked
by nitric acid.
OXIDIZING MINERAL ACIDS + NITRIDES
Nitrides are extremely strong bases and will participate in
an acid-base reaction evolving much heat. This reaction can pro-
ceed with explosive violence due to the instability of metal
nitrides and the generation of flammable ammonia gas.
OXIDIZING MINERAL ACIDS + NITRILES
The primary hazard in mixing these types of compounds appears
to be oxidation of the nitriles with generation of heat
and toxic fumes of nitrogen oxides. In some cases such as
acetone cyanohydrin and propionitrile, extremely toxic hydrogen
cyanide gas is known to result from ciising with strong acids.
These fumes are also flammable. Mixtures of nitric acid and
acetonitrile are high explosives.
OXIDIZING MINERAL ACIDS + NITRO COMPOUNDS
These acids can decompose nitro compounds to produce heat
and toxic fumes of nitrogen oxide. This oxidation can be
extremely violent. Mixtures.of nitric acid and nitro-
aromatics are known to exhibit explosive properties.
Mixtures of some nitroalkanes (nitronethane) with nitric
acid can also be detonated.
OXIDIZING MINERAL ACIDS + UNSATURATED ALIPHATICS
Aliphatic unsaturated hydrocarbons are extremely susceptible
to oxidation resulting in heat generation and fire.
-------
OXIDIZING MINERAL ACIDS + SATURATED ALIPEATICS
Aliphatic saturated hydrocarbons are easily oxidized by
these acids yielding heat and carbon dioxide.
OXIDIZING MINERAL ACIDS + ORGANIC PEROXIDES
The lower molecular weight organic peroxides and hydro-
peroxides are very sensitive to heat and shock. Mixing
•j - \ : • i
of oxidizing mineral acids with such unstable compounds
»• . . '
can cause heat generation due to the oxidizing capacity of
the acids and acid catalyzed hydrolysis. These reactions
can cause explosive decomposition.
OXIDIZING MINERAL ACIDS + PHENOLS AND CRESOLS
Phenols and cresols are easily oxidized and excess oxidizing
acids can result in much heat generation.
OXIDIZING MINERAL ACIDS - + ORGANOPHOSPHATES
Excess oxidizing acid can decompose these compounds to yield
heat and toxic fumes of nitrogen oxides, sulfur oxides, and
phosphorous oxides.
OXIDIZING MINERAL ACIDS + WATER AND WATER MIXTURES
Much heat can be evolved from the dissolution of these
acids by water.
OXIDIZING MINERAL ACIDS + SULFIDES
Toxic and flammable hydrogen sulfide gas can be generated by
the action of these acids on inorganic sulfides. These
sulfides can also be oxidized exothemically to sulfur dioxide,
also a toxic gas. This reaction can occur very violently.
OXIDIZING MINERAL ACIDS + EPOXIDES
Epoxides are very easily cleaved by acids with heat generation.
-------
This ring opening can be the initiating step in the formation
of epoxy resins, and uncontrolled polymerization can result in
extreme lieat generation. The oxidation capacity of these
acids can cause ignition of the epoxides.
OXIDIZING MINERAL ACIDS + COMBUSTIBLE MATERIALS
Oxidizing mineral acids can decompose some substances with heat
generation and possible fire. Toxic gases may also be formed
as combustion products, but the type of gas will depend upon
the composition of these miscellaneous substances.
OXIDIZING MINERAL ACIDS + EXPLOSIVES
Such strong acids can easily detonate compounds in this group
of explosives due to the heat generated upon mixing. The
oxidizing character of these acids merely enhances the
possibility of detonation.
OXIDIZING MINERAL ACIDS + POLYMERIZABLE COMPOUNDS
These acids can act as initiators in the polymerization of
many compounds. These reactions are exothermic and can
occur violently. In addition, these acids can oxidize
certain compounds producing more heat and possible toxic
fumes.
OXIDIZING MINERAL ACIDS + STRONG REDUCING AGENTS
Mixing of compounds in these two groups can result in very
violent, extremely exothermic reactions. Fires and explosions
can result.
ORGANIC ACIDS + ALDEHYDES
Exothermic condensation reactions can occur between these
two types of compounds. The acidic character of the organic
-------
acids may be sufficient to catalyze the reaction. Polybasic and
unsaturated acids are susceptible to polymerization under these
condition, resulting in much heat generated.
ORGANIC ACIDS + AMINES
An acid-base reaction between the stronger acids and amines
can generate some heat. Dicarboxylic acids and diamines
can copolymerize with heat generation.
ORGANIC ACIDS + AZO COMPOUNDS
Aliphatic and aromatic diazo compounds are readily decomposed
by organic acids releasing heat and nitrogen gas as reaction
products. Azo compounds are not sensitive to such decomposition.
Hydrazine azide is extremely sensitive to heat or shock. An
acid-base reaction with hydrazine can produce some heat.
ORGANIC ACIDS + CAUSTICS
Acid-base reactions produce heat.
ORGANIC ACIDS + CYANIDES
Hydrogen cyanide, an extremely toxic and flammable gas, is
generated upon mixing.
ORGANIC ACIDS + DITHIOCARBAMATES
Toxic and flammable carbon disulfide can be formed upon
contact of dithiocarbamate with the stronger organic acids.
Although CS2 is a liquid at room temperature, it has a very
high vapor pressure. Some heat can be generated from the
hydrolysis of the dithiocarbamate salts.
ORGANIC ACIDS + FLUORIDES
Toxic and corrosive hydrogen fluoride fumes can be generated
by the action of strong organic acids upon metal fluoride
-------
salts. Alkali metal fluorides are especially susceptible
to decomposition in this manner.
ORGANIC ACIDS + ISOCYANATES
Some water is normally associated with organic acids, and
this can cause hydrolysis of isocyanates to carbon dioxide
and amines with some heat generated.
ORGANIC ACIDS + ALKALI AND ALKALINE EARTH METALS
Reaction of organic acids with these metals in any form
can result in exothermic generation of flammable hydrogen
gas and possible fire.
ORGANIC ACIDS + METAL POWDERS, VAPORS, AND SPONGES
The stronger organic acids can liberate flammable hydrogen
gas upon contact with metals in these forms. The heat of
reaction can cause explosions.
ORGANIC ACIDS + NITRIDES
An acid-base reaction can occur resulting in heat and possible
evolution of flammable ammonia gas. Many of these nitrides
are explosively unstable and can be detonated by the heat of
reaction.
ORGANIC ACIDS + NITRILES
Strong organic acids can convert nitriles to their corres-
ponding organic acid with some heat generation.
' ORGANIC ACIDS + SULFIDES
Extremely toxic and flammable hydrogen sulfide and some heat
can be generated.
ORGANIC ACIDS + EPOXIDES
Acid catalyzed cleavage of the epoxide ring can initiate
-------
violent polymerization with much heat generated.
ORGANIC ACIDS + EXPLOSIVES
Strong organic acids can decompose compounds in this group
resulting in enough heat to cause detonation.
ORGANIC ACIDS + POLYMERIZABLE COMPOUNDS
Strong organic acids can initiate cationic polymerization.
Dicarboxylic acids can copolymerize with diamines as in the
reaction of adipic acid and hexamethylene diamine to form
Nylon 6,6.
ORGANIC ACIDS + OXIDIZING AGENTS
The hydrocarbon moeity of the organic acids are susceptible
to decomposition by strong oxidizing agents releasing heat and
gas. The gas produced can be toxic if the acid contains
halogens such as dichlorophenoxy acetic acid, or if it contains
other hetero atoms.
ORGANIC ACIDS + REDUCING AGENTS
Carboxylic acids are easily reduced by lithium aluminum
hydride to the corresponding alcohols with some heat genera-
tion. Other reducing agents require more vigorous reaction
conditions. Flammable hydrogen gas can be produced from the
extractions of the hydroxyl proton and the ^ -hydrogens.
CAUSTICS -I- ESTERS
Esters are easily hydrolyzed by caustics to a salt and
alcohol with heat generation.
CAUSTICS + HALOGENATED ORGANICS'
Aliphatic halides can undergo substitution or dehydro-
halogenation upon treatment with strong caustics. Both
-------
processes involve some heat generation while the second
evolves flammable olefins and acetylenes, especially with
the lower molecular weight compounds. Halogenated aromatics,
however, are relatively stable to strong caustics.
CAUSTICS + ISOCYANATES
Caustics catalyze the polymerization of diisocyanates
yielding much heat. The mono isocyanates decompose to
amines and carbon dioxide upon contact with caustics.
CAUSTICS + KETONES
Caustics can catalyze the self-condensation of ketones,
yielding heat.
CAUSTICS + ALKALI AND ALKALINE EARTH MET.M.S
Heat and flammable hydrogen gas can be generated due to the
aqueous nature of most caustics.
CAUSTICS 4- METAL POWDERS, VAPORS, AND SPONGES
Heat and flammable hydrogen gas may be generated with some
metals such as aluminum, magnesium, zinc, and beryllium.
Explosions may also occur due to the high surface area of
these forms.
CAUSTICS + NITRO COMPOUNDS
Nitro alkanes and caustics form salts in the presence of
water. The dry salts are explosive.
CAUSTICS + ORGANOPHOSPHATES
Alkaline hydrolysis of phosphorothioates can generate
enough heat to cause explosive rearrangement from the
thiono to the thiolo form. Hydrolysis of other organo-
phosphates can generate heat.
-------
CAUSTICS -I- EPOXIDES
Base catalyzed cleavage can result in polymerization with
much heat.
CAUSTICS + EXPLOSIVES
Alkaline hydrolysis or other reactions can generate
enough heat to detonate these compounds.
CAUSTICS + POLYMERIZABLE COMPOUNDS
These compounds can undergo anionic polymerization with
caustics as initiators yielding much heat.
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