dispose
0,
icide
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An environmental protection publication (SW-519) in the solid waste
management series. Mention of commercial products does not constitute
endorsement by the U.S. Government. Editing and technical content of
this report were the responsibilities of the Hazardous Waste Management
Division of the Office of Solid Waste Management Programs.
4
Single copies of this publication are available from Solid Waste
Information, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268.
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DISPOSAL OF DILUTE PESTICIDE SOLUTIONS
This report (SW-519) was prepared
by Harold R. Day
U.S. ENVIRONMENTAL PROTECTION AGENCY
1976
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TABLE OF CONTENTS
Summary 1
Summary Table of Disposal Methods 3
I. Introduction 4
II. Identification of Sources 4
A. Container Rinsate
B. Equipment Washing
C. Water From Fires
D. Pesticide Spills
E. Reconditioning Operations
III. Potential Impacts of Improper Disposal 7
IV. Current Disposal Practices 8
A. Use as Diluent
B. Holding Tanks, Disposal Pits, and Dry Wells
C. Soil Injection
D. Chemical Detoxification
E. Incineration
F. Photodecomposition
G. Batch Biodegradation
H. Special Disposal Sites
V. Economic Considerations 12
VI. Regulations 13
VII. Current Studies on Rinsate Disposal 15
A. Chemical Degradation
B. Soil Injection Studies
C. Incineration
D. Filtration Studies
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Summary
Disposal of dilute pesticide solutions has, in the past, been
addressed only in a general way. This report seeks to highlight the
problem, identify sources of dilute solutions, describe current disposal
practices, and consider factors which influence a choice among them.
These dilute solutions are generated by container rinsing, equipment
washing, water from pesticide fire-fighting operations, spill clean-ups,
and drum reconditioning operations. If disposed of carelessly, the
contained pesticides can build up to toxic levels in soils, deactivate
sewage treatment plants, etc..
Nine disposal methods currently in use have been identified and are
discussed. These methods together with their characteristics are
summarized in Table 1.
Incineration and batch biodegradation are limited by high cost,
complexity, and low availability. For these reasons, they are generally
restricted to treating process waste from manufacturing operations.
Photodecomposition and chemical degradation can be effective under
correct conditions, but neither provides complete assurance of degradation
for all pesticides and their degradation products. Lagooning is one
method used principally by manufacturers to provide light for photo-
decomposition to occur. Chemical degradation requires specific reactants and
procedures for each pesticide, but reaction products also must be disposed
of safely.
Soil injection and gravel-filled pits are primarily biodegradation
methods. Given enough time, organic pesticides degrade to innocuous products,
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However, the conditions needed for optimum decomposition of all pesticides
and their metabolites are extremely variable and not well defined. A potential
for water contamination through leakage or leaching from a disposal site
exists unless its location and method of operation will reduce mobility,
avoid contact with groundwater, and promote biodegradation. Because no
pretreatment is needed, this method is low cost.
Long term storage in special land disposal sites offers a last resort
to the disposer. In addition to being costly, this option may not lead
to degradation of the pesticide, but merely isolate it from the environment.
Special land disposal sites are generally unavailable and user fees may be
high; however, for some pesticide solutions, particularly the inorganic
and heavy metal types, this option may be the best answer.
Whenever possible, use of dilute solutions as a diluent for making
up spray mixtures, is the most reliable and desirable method for disposal.
Other methods discussed here are potentially valuable and should be explored.
The choice of method will depend on the nature of the pesticide, the concentration,
local disposal costs, and destruction assurance. The reliability, safety,
and disposal parameters for dilute pesticide solutions are the subject of
current studies.
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Method
Use as diluent
in spray tank
Incineration
Soil Injection
TABLE 1
SUMMARY OF CHARACTERISTICS OF DISPOSAL METHODS
FOR DILUTE PESTICIDE SOLUTIONS
Cost
Availability Ease of Method Environmental Hazards and Comments
None
High
Low
High
Low
High
Photodecomposition
Chemical
degradation
Batch Biodegradation
Disposal pits
Special landfills
Storage
None
Moderate
High
Variable
High
Low
Moderate Low
Moderate Low
Moderate High
Easy
None(if used according to label)
Moderately, None(if incinerator is adequate)
difficult
Easy Miniraal(at low rates); requires
variable time for destruction,
and may restrict crop rotation.
Water contamination possible
at improper sites.
Easy Unreliable and generally incomplete
degradation. Soil erosion may
transport pesticides to surface
waters.
Moderate Chemical method must be specific
for the pesticide in question.
Reaction may not be complete.
Disposal of reaction products
necessary.
Difficult, Not generally available; too
complex complex for present general use.
Easy May be more effective than soil
injection. May contaminate ground
or surface water if not constructed
or sited properly.
Moderate May not degrade pesticides;
landfills may not accept liquids.
Easy Merely delays disposal.
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I. Introduction
This paper draws together current information on the subject of disposal
of excess dilute pesticide solutions. Such solutions are comprised of unused
spray, container rinsate, equipment washings, spill clean-ups, etc., and
are defined as equal to or less than the recommended application concentration.
This effort seeks to identify the sources of these solutions, current disposal
practices, environmental hazards, and costs of disposaJmethods available.
Federal regulatory efforts regarding pesticide disposal and current research
on disposal methods are briefly summarized.
This paper reflects the current state-of-the-art and has been
gathered from sources within and outside the U.S. Environmental Protection
Agency (EPA). Information presented is intended for information only,
and should not be construed as Agency policy.
II. Identification of Sources
There are five major sources of dilute pesticide solutions requiring
disposal:
A. Container Rtnsate
Residues from rinsing of noncombustible pesticide containers are a large
source of excess pesticide solutions. It has been estimated that farmers
used 630 million pounds of pesticides and 20 million noncombustible
containers in 1966, the latest estimates available. Current EPA and industry
recommendations call for triple-rinsing of such containers prior to
disposal. The procedure is to make three successive rinses each with
a volume of the normal diluent equal to 10 percent of the container volume.
Assuming that all applicators rinsed their 1-, 5-, 30-, and 55-gallon
containers in 1966, 6 million gallons of solution containing some
pesticide would have been generated.
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With current pesticide use in this country estimated at about 1 billion
pounds, the number of pesticide containers has probably increased
significantly.
In real practice, few applicators rinse their containers prior to
disposal. In a recent survey of Iowa cooperatives, for example, it was
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estimated that only five percent of the applicators did so. In these cases,
the most common method of rinse disposal was to drain to the soil surface.
2
In recent years, through the efforts of EPA, the U.S. Department
of Agriculture (USDA), the National Agricultural Chemicals Association
(NACA), the Western Agricultural Chemcals Association (WACA), and some
container reconditioners, the applicator has been urged to triple-rinse
containers so they will be safer to handle for reuse, recycling, or disposal,
Only a very small amount of pesticide residue remains within the containers
which are triple-rinsed immediately after being emptied. Hence triple-
rinsed containers are considered acceptable for disposal in a sanitary
landfill. Applicators are being told it is economically advantageous
to rinse containers; all the pesticide is utilized and the container
can be sold more easily or disposed of in a sanitary landfill. Some
container recondtioners will not take unrinsed containers.
Other recent developments of a regulatory nature will promote
triple-rinsing. State laws may require it. New label directions will
require it as party of the reregistration process, and certification
training will increase the applicator's awareness and stress the
advantages to be gained.
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B. Equipment Washing
Another source of dilute pesticide solution is the washing or rinsing
generally with water, of application equipment including spray tanks, mixing
tanks, holding tanks, trucks, and airplanes. The volume generated is
difficult to estimate because rinsing practices and equipment differ with
each applicator. One source has estimated that aerial applicators in the
United States use 100 million gallons of water for washing per year and
another 2,500 custom applicators use about 6 million gallons of water.3
Various estimates indicate that about a million farmers are users of
pesticides; most generate waste water containing some pesticide in washing
out their application equipment. According to the Iowa survey, most farmers
allow the rinsate to drain on to the soil surface.
C. Water f ran Fires
An uncommon but real problem which can arise is a fire associated
with stored pesticides. Water in large volumes from a firefighting
operation becomes contaminated after contact with uncombusted or partially
combusted pesticides. Recent cases of such fires in Minnesota and West
Virginia have highlighted this potential source of large volumes of water
containing pesticide.4'5 In the Minnesota case, 40,000 gallons of contaminated
water were recovered. The disposal was complicated because many different
pesticides were present, each with its own hazards and degradation
characteristics. In some cases absorbents can be used to hold the waste,
but then such materials will need disposal. The West Virginia case
generated 750,000 gallons of water which was sealed at the site with
concrete.
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D. Pesticide Spills
Spills of pesticide often demand quick action, particularly if the
pesticide is highly toxic. Applications are made of lime, absorbents,
5
or other chemicals including liberal amounts of water. Contained spills
often are cleaned up, and residues and solutions placed in containers for
disposal. Between 1971 and 1973, 35 spill incidents involving pesticides
were reported to EPA.
E. Reconditioning Operations
A drum reconditioner uses chemical rinses, fire, shot blasting, and
special machinery to clean and straighten old steel drums for reuse,
including some which formerly contained pesticides. The reconditioner
usually first deheads the drums and washes the interior prior to
burn-out. It is estimated that about 5 million pesticide drums are
reconditioned per year requiring 5 million gallons of water. This
wash water, containing some pesticide and other chemicals, is commonly
disposed of via the sewer system. However, the Federal Water Pollution
Control Act regulations will limit this practice and Federal Insecticide,
g
Fungicide and Rodenticide Act, as amended, regulations will prohibit it.
Therefore, safe alternatives will have to be found for disposal of these
solutions.
III. Potential Impacts of Improper Disposal
Improper disposal of dilute pesticide solutions can present a
hazard to man, livestock, crops, and the environment. Dilute solutions
have been shown to result in fish kills and destruction of other aquatic
fauna.
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Contamination of surface water by directly emptying rinsate into
ponds, lakes, and rivers could result in a concentration of pesticide
lethal to fish and other aquatic life.
Indiscriminate dumping in soil could indirectly contaminate wells,
water supplies, and flora in an area. Soil microorganisms could also
be adversely affected. Such contamination can be difficult and expensive
to correct.
Pesticides which are persistent (resisting degradation) could
accumulate in soil and serve as a reservoir for chronic contamination.
Additionally, metabolites of pesticides can be as toxic as the pesticide
and resist degradation. These factors emphasize the need for great care
in disposal to avoid polluting surface and subsurface waters.
IV. Current Disposal Practices
A. Use as Diluent
Using dilute pesticide solutions as a diluent for spray mixtures
is the most economical, easiest, and most desirable disposal method. With
this practice, the material is utilized for its original intended purpose.
It has long been recommended by Government and industry authorities, and
assures that the pesticide is used according to label directions. Economically,
the applicator benefits because he is able to utilize the quantity of
pesticide that normally remains in the container after draining (a cup or
more; enough for 1/2 acre in some cases). The rinsed container can then
be recycled, reused, or scrapped and is safer to handle. Costly methods
of disposal are avoided since this preferred disposal method can be accomp-
lished on-site where the spray mix is prepared.
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B. Holding Tanks, Disposal Pits, and Dry Wells
Methods of disposal utilizing a receptacle in the ground have
been used by some applicators for pesticide solutions. In some cases ,
a dry well filled with aggregate rock is used. The rinsate is allowed to
drain from equipment, flow over aggregate, and eventually seep into the soil.
A variation of this is a concrete-lined pit filled with stones, gravel, etc.
The spraying equipment is placed directly over the rocks and rinsed. The
rinsate is held in the pit, and the water evaporates. Biodegradation
may also take place, but no firm evidence of how or at what rate this
process occurs is available. Buried septic tanks and leaching fields
are also used. Lagooning is less desirable because volatile pesticides
are exposed on the surface. In this method, rinsate is stored in an
impoundment and allowed to evaporate; some degradation (by photolysis)
may take place.
None of these methods have been shown to be completely reliable
or safe. Concentration by evaporation can lead to dangerously potent residues.
Holding tanks and pits may contaminate subsurface water, and lagooning
exposes the environment directly to pesticide wastes. More testing
of these methods is needed to establish parameters for biodegradation
by these methods.
C. Soil Injection
Injection of dilute organic pesticide solutions by ordinary farm
implements (plows, harrows, etc.) beneath the surface of the soil into the
plow layer takes advantage of the biodegradation ability of soil microorganisms
If the concentration is dilute and spread over a large area, degradation of
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many organic pesticides occurs rapidly. Soil microbes such as fungi and
bacteria can be acclimated to use toxic organic substrates as energy sources.
The variables affecting this process are difficult to measure and quantify;
soil moisture, organic matter content, base exchange capacity, and temperature
are all important to the biodegradation process. Further, a mixture of
pesticides can effectively reduce a soil micro-flora population. More
hard data are needed to obtain a clearer picture of the variables involved
in soil degradation. Potentially, the soil injection method is the least
expensive option open to applicators. No special equipment is needed; no
transportation costs are incurred. Hie most desirable fact is that many
organic pesticides are eventually destroyed, although the time required will
vary with the conditions and the chemical characteristics of the pesticide.
D. Chemical Detoxification
Dilute pesticide solutions also can be degraded chemically, Organophos-
phates, carbamates, and other pesticide classes are susceptible to chemical
action such as acid or alkaline hydrolysis and chemical oxidation or
reduction. Most pesticides can be degraded chemically but many require
exotic reactants and conditions.
The problems encountered in chemical degradation are two-fold. First,
each pesticide possesses specific chemical characteristics, and a chemical
method must be specific to it. Edgewood Arsenal reports that no universal
chemical is effective against all pesticides . A second problem is that
chemical action is not complete, thereby leaving unreacted pesticide. In
some cases, reaction byproducts formed are as hazardous as the original
pesticide.
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Pursuant to FIFRA registration and label regulations, pesticide
producers will be asked to find simple methods for disposal of
their pesticides, and put appropriate directions on the label of the
container. In some cases, where chemical methods are dangerous (e.g., where
highly toxic products are formed or dangerous reactants and conditions are
used), specific warnings also should be made.
E. Incineration
Destruction of dilute organic pesticide solutions by incineration
is an effective method if sufficiently high temperatures and suitable
I O
dwell times are used. IIL Also, adequate emmission controls (scrubbers, etc.)
must be present. The largest drawback to this method is the large
expenditure of energy needed to drive off the solvent (commonly water).
"I o
Few incinerators10 in this country are capable of meeting the stringent
requirements of a pesticide incinerator (1000 C, 2 seconds dwell-time),
and their availability to most applicators is low.
F. Photodecompos i ti on
Studies have shown that some pesticides exposed to light may be degraded
or altered. When placed on the soil surface or in a lagoon, photode-
gradation reactions produce materials which are undefined in many cases
as well as reactions which often are incomplete. However, in some cases
(e.g., atrazine), it may be a desirable first step before soil degradation.
6. Batch Biodegradation
Biological degradation of pesticides in solution has been the subject
of previous investigations. Results indicate that Parathion and 2,4-D
can be completely degraded in controlled culture media. Major drawbacks
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are slowness, expense, and complexity of the system. Cultures of micro-
organisms, which can produce enzymes that degrade pesticides, are subject
to contamination and mutation limiting their activity. '4>15 jne cultures
must be isloated and maintained; generally, only one pesticide can be
degraded at a time with a specific microorganism. Expense and complexity
has restricted this method to laboratory experimental units and pesticide
production and formulation plants.
H. Special Land Disposal Sites
Dilute pesticide solutions may be disposed of in a land disposal site
which is designed and approved to accept hazardous wastes. Such sites are
designed to avoid groundwater contamination, are secure, and any leachate
generated is confined to the site unless it is subsequently detoxified.
A common method used by drum reconditioners is to place old containers
filled with rinsate in a separate part of a disposal site and surround
them with cover material. As the containers corrode, the rinsate is absorbed
by the ground cover'6; however, little is known about the eventual fate of the
pesticide, and many disposal site operators, as well as State and local
officials, are reluctant to permit the practice. Studies of leachate from
these specific areas of disposal site would yield useful data.
V. Economic Considerations
Although improper disposal of pesticide solutions constitutes a threat
to man, livestock, crops, land and water, applicators, faced with the
disposal of dilute pesticide solutions, will seek the least expensive
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and most convenient method available. Use as a diluent is the preferred
and least cost method. The pesticide saved is worth (on the average)
about one dollar per drum, and the applicator does not have to pay disposal
costs.
Container rinsate, water from fires, and water from spills which
are difficult to recover and may be contaminated are usually buried or
allowed to drain to the ground. While inexpensive initially (only the
disposer's time is considered) and convenient, this method can be
hazardous and costly in the long term because of possible environmental
damage requiring an expensive cleanup.
Other methods such as incineration (about $75-100/ton), chemical
degradation ($50-100/ton), and special landfill disposal (about $30-50/ton)
are more expensive, and also may not be available to the disposer. Some
landfills will not accept liquids.
Soil injection and disposal pit costs are difficult to estimate.
A concrete-lined disposal pit can be constructed for about $4500, and
may last for 5 to 10 years depending on quantities disposed. Unlined
pits cost less. Soil injection can be accomplished with ordinary equipment
at variable costs, ranging from $10 to 20 per hour; typically, not more
than 15 to 20 minutes would be required to inject one day's accumulation
or rinsate.
VI. Regulations
Over the past 2 years Federal regulatory effort relating to pesticide
disposal have been made under the authority of FIFRA, as amended.
A. Disposal Regulations and Recommended Procedures
On May 1, 1974, EPA published "Recommended Procedures for Disposal
2
and Storage of Pesticide and Pesticide Containers" . The disposal of
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dilute pesticide solutions is addressed in a general way; the same
procedures that apply for pesticides are recommended for dilute solutions.
The procedures state that pesticide waste should be disposed (on a priority
basis) by: use as a diluent in the spray tank, incineration (organics only).
emplacement in a specially designated landfill, soil injection with EPA
Regional office guidance, chemical degradation, or storage. These options
are regulatory for Federal agencies, but not for the public.
8
On October 15, 1974, EPA proposed prohibitionary regulations which would
prohibit the worst acts of pesticide disposal—open dumping, open burning,
water and ocean dumping—and would restrict well injection ,and storage next
to food and feed. These regulations, when final, will apply to everyone;
the disposal of pesticide containers, pesticides, and related residues
(including dilute pesticide solutions such as excess spray solutions and
rinsate) will be impacted.
B. Registration and Labeling Regulations
New regulations for registration and reregistration of pesticides
require that labels on containers include instructions for disposal,
and manufacturers must submit proposed labels and appropriate documentation
by October, 1977. To comply, companies will be forced to supply information
on how to dispose of the specific pesticide, the container, and the residues
thereof. Directions for disposal will vary with the chemical nature of the
pesticide and the size and type of container. Open dumping, water contamination,
and food/feed contamination will be prohibited in all cases; triple
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rinsing (or equivalent) will be a common requirement. Disposal in
approved landfills will be required if the waste pesticides, rinsate,
or containers cannot be disposed of otherwise.
VII. Current Studies on Rinsate Disposal
A. Chemical Degradation
Currently, EPA has a contract with TRW, Systems Group,Inc.,to
gather information from the literature and pesticide manufacturers on
chemical disposal of 20 widely-used pesticides. The report
will discuss the results of reacting pesticides with common chemicals,
such as caustic soda and hypochlorite, and identify those products that
applicators can safely degrade. Equally important will be the
identification of products that can be safely handled only by experts.
The output will be in language and terms that can be readily understood
by applicators, and will furnish basic guidance and precautions to be
observed.
B. Soil Injection Studies
Oregon State University (OSU) recently completed an EPA-sponsored study
on the effectiveness of triple-rinsing and residue disposal. The soil
injection study utilized a pesticide manufacturing waste (mainly 2,4-
dichlorophenol), and the results are indirectly applicable to soil
injection of dilute pesticide solutions. The work indicated that
the method is more effective when low rates (500 pounds per acre or less)
are injected and sufficient time (18 months or more) is allowed for
degradation to occur.
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C. Incineration
12
Midwest Research Institute (MRI) recently completed a study
on combustion of pesticides. The study shows that high temperatures
(1000 C) over sufficient time (2 seconds) effectively decompose organic
pesticides and destroy intermediate products formed at lower temperatures.
Adequate emission control devices must be present to prevent release of
hazardous combustion products (e.g., HC1) to the environment and to prevent
damage to equipment. Limiting factors are temperature, time, excess air,
and turbulence.
D. Filtration Studies
OSU, as part of their final report, included a study on deactivation
of dilute pesticide solutions by filtration. Preliminary results indicate
that activated carbon, dried sewage sludge, pine bark dust, and synthetic
resins can be used to reduce pesticide concentrations in aqueous solutions
to one part per million or less. Major advantages are transfer of
contaminants to a solid phase and volume reduction. Filtration material
can be disposed of by regeneration, incineration, by burial in a designated
18
landfill, or by soil incorporation. None of these filtration methods has
been investigated in detail.
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REFERENCES
1. Arthur D. Little, Inc. Economic analysis of pesticide disposal methods;
final report. Washington, U.S. Environmental Protection Agency, Strategic
Studies Unit, Mar. 1975. various pagings. (Unpublished report.)
2. U.S. Environmental Protection Agency. Pesticides and pesticide containers;
regulations for acceptance and recommended procedures for disposal and
storage. Federal Register, 39(85):15235-15241, May 1, 1974.
3. Personal communication. A. Johnson, Air Enterprises, Inc., to H. R. Day,
Office of Solid Waste Management Programs.
4. Personal communication. Region V, U.S. Environmental Protection Agency,
to H. W. Trask, Office of Solid Waste Management Programs.
5. Personal communication. Fire Marshall, Charleston, W. Va., to H. R. Day,
Office of Solid Waste Managment Programs.
6. Moore, E.E. Disposal of unwanted excess pesticides and empty containers.
Journal of Environmental Health, 36(3):238-243, Nov.-Dec. 1973.
7. Personal communication. National Barrel and Drum Association to H. R. Day,
Office of Solid Waste Management Programs.
8. U.S. Environmental Protection Agency. Pesticides; EPA proposal on
disposal and storage. Federal Register, 39(200) :36847-36950,
October 15, 1974
9. Guenzi, W. D., ed. Pesticides in soil and water. Madison, Wis.,
Soil Science Society of America, Inc., 1974. 562 p.
10. Personal communication. H. J. Stockdale, Iowa State University, to
H. R. Day, Office of Solid Waste Management Programs.
11. Dennis, W. H., Jr. Methods of chemical degradation of pesticides and
herbicides—a review. Edgewood Arsenal, Md., Army Medical Environmental
Engineering Research Unit, Oct. 1972. 36 p. (Distributed by National
Technical Information Service, Springfield, Va., as AD-752 123.)
12. Ferguson, T. L., et al. [Midwest Research Institute]. Pilot scale
incineration of pesticides, v.2. Washington, U.S. Environmental
Protection Agency, Office of Research and Monitoring, 1975.
Iv.(various pagings). (Unpublished report.)
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13. Farb, D., and S.D. Ward. Information about hazardous waste management
facilities, Environmental Protection Publication SW-145.
[Washington], U. S. Environmental Protection Agency, Feb. 1975.
130 p.
14. Munnecke, D. M., and D. P- Hsieh. Microbial decontamination
of parathion and p-nitrophenol in aqueous media. Applied
Microbiology, 28(2):212-217, Aug. 1974.
15. Stanford Research Institute. Unpublished data.
16. Pierce, R. H., C. E. Olney, and G.T. Felbeck, Jr. Pesticide
adsorption in soils and sediments. Environmental Letters,
1(2) :157-172, 1971.
17. Goulding, R. L. Waste pesticide management; July 1, 1969-June 30, 1972,
and Jan. 17, 1974-June 30, 1974. [Washington], U.S. Environmental
Protection Agency, Office of Solid Waste Management Programs,
June 30, 1974. 269 p. (Unpublished report.)
18. Personal communication. U.S. Environmental Protection Agency
Laboratory, Edison, N.J., to H. R. Day. Office of Solid Waste
Management Programs.
MCT1299
SW-519
-& U.S. GOVERNMENT PRINTING OFFICE: 1976- 625-55/434
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